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Nd Isotopes throughout the North Atlantic in the Late Cretaceous and across the Oceanic Anoxic Event 2

University of Florida Institutional Repository
Permanent Link: http://ufdc.ufl.edu/UFE0022706/00001

Material Information

Title: Nd Isotopes throughout the North Atlantic in the Late Cretaceous and across the Oceanic Anoxic Event 2
Physical Description: 1 online resource (147 p.)
Language: english
Creator: Bourbon, Elodie
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2008

Subjects

Subjects / Keywords: atlantic, bermuda, blake, cape, circulation, cretaceous, demerara, ferromaganese, fish, goban, isotopes, late, neodymium, north, nose, oae2, oceanic, oxides, rise, spur, teeth, verde
Geological Sciences -- Dissertations, Academic -- UF
Genre: Geology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The Cenomanian/Turonian boundary coincides with the Late Cretaceous thermal maximum, the formation of the Caribbean Large Igneous Province (LIP) and Oceanic Anoxic Event 2 (OAE 2), which represents a dramatic perturbation of the global carbon cycle. Late Cretaceous oceanic circulation in the North Atlantic is poorly known, yet it could be important for understanding the dynamic conditions that led to OAE 2. Neodymium isotopic compositions of fossil fish teeth/debris and Fe-Mn oxide coatings from Ocean Drilling Program sites on Demerara Rise, Blake Nose, Bermuda Rise, Cape Verde and Goban Spur were used to reconstruct the evolution of North Atlantic deep ocean circulation in the Late Cretaceous and investigate the relationship between ocean circulation and the formation of OAE 2. All of the sites with positive carbon isotope excursions at OAE 2 also record a positive ?Nd shift, which varies from ~1 to 8 ?Nd units depending on the completeness of the record. Extractions of Nd from dispersed Fe-Mn oxide coatings from samples before, during and after the excursion yield ?Nd values that are consistent with data from fish teeth apatite, indicating that both mineral phases are robust archives for Nd isotopes in a range of lithologies and redox conditions. Non-radiogenic ?Nd values ranging from -14 to -17.5 and a lack of stratification in ?Nd observed at the Demerara Rise depth transect sites suggest local ventilation of warm, saline water, referred as to the Demerara intermediate water (DIW), to intermediate depths. This water mass appears to have delivered a very non-radiogenic ?Nd signal, presumably from a local riverine source draining from the Guyana Shield, to intermediate depths continuously from the late Albian-Cenomanian to the late Maastrichtian with a brief interruption during OAE 2. The ~6 to 8 ?Nd unit peak at Demerara Rise during OAE 2 suggests DIW may have shut down over this interval, possibly due to an enhanced hydrologic cycle. Apparently this local bottom water source mixed with or was replaced by water from the larger North Atlantic circulation system. Widespread distribution of positive ?Nd shifts during OAE 2 throughout the North Atlantic implies OAE 2 formation was associated with a basin-wide process such as 1) hydrothermal input of Nd associated with the formation of the Caribbean LIP and/or 2) reorganization of deep oceanic circulation. Yet, Nd isotopic data do not uniquely distinguish between these scenarios and further analyzes are required. General Late Cretaceous circulation patterns based on the distribution of ?Nd data indicate that the Tethys Seaway was the major source of deep water in the North Atlantic during the Albian and Cenomanian. Neodymium values in the western North Atlantic represent a mixture of less radiogenic Tethys and more radiogenic Pacific waters and argue against sluggish conditions. Nd and oxygen isotopic data support the initial opening of the Equatorial Atlantic Gateway between the North and South Atlantic in the Turonian-Santonian that allowed the introduction of cooler, South Atlantic deep waters with ?Nd values of ~-9. Finally, ?Nd values at Demerara Rise shift from unique non-radiogenic background values to more Atlantic-like values in the mid to late Maastrichtian suggesting the end of conditions necessary for formation of the DIW.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Elodie Bourbon.
Thesis: Thesis (M.S.)--University of Florida, 2008.
Local: Adviser: Martin, Ellen E.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2010-08-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2008
System ID: UFE0022706:00001

Permanent Link: http://ufdc.ufl.edu/UFE0022706/00001

Material Information

Title: Nd Isotopes throughout the North Atlantic in the Late Cretaceous and across the Oceanic Anoxic Event 2
Physical Description: 1 online resource (147 p.)
Language: english
Creator: Bourbon, Elodie
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2008

Subjects

Subjects / Keywords: atlantic, bermuda, blake, cape, circulation, cretaceous, demerara, ferromaganese, fish, goban, isotopes, late, neodymium, north, nose, oae2, oceanic, oxides, rise, spur, teeth, verde
Geological Sciences -- Dissertations, Academic -- UF
Genre: Geology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The Cenomanian/Turonian boundary coincides with the Late Cretaceous thermal maximum, the formation of the Caribbean Large Igneous Province (LIP) and Oceanic Anoxic Event 2 (OAE 2), which represents a dramatic perturbation of the global carbon cycle. Late Cretaceous oceanic circulation in the North Atlantic is poorly known, yet it could be important for understanding the dynamic conditions that led to OAE 2. Neodymium isotopic compositions of fossil fish teeth/debris and Fe-Mn oxide coatings from Ocean Drilling Program sites on Demerara Rise, Blake Nose, Bermuda Rise, Cape Verde and Goban Spur were used to reconstruct the evolution of North Atlantic deep ocean circulation in the Late Cretaceous and investigate the relationship between ocean circulation and the formation of OAE 2. All of the sites with positive carbon isotope excursions at OAE 2 also record a positive ?Nd shift, which varies from ~1 to 8 ?Nd units depending on the completeness of the record. Extractions of Nd from dispersed Fe-Mn oxide coatings from samples before, during and after the excursion yield ?Nd values that are consistent with data from fish teeth apatite, indicating that both mineral phases are robust archives for Nd isotopes in a range of lithologies and redox conditions. Non-radiogenic ?Nd values ranging from -14 to -17.5 and a lack of stratification in ?Nd observed at the Demerara Rise depth transect sites suggest local ventilation of warm, saline water, referred as to the Demerara intermediate water (DIW), to intermediate depths. This water mass appears to have delivered a very non-radiogenic ?Nd signal, presumably from a local riverine source draining from the Guyana Shield, to intermediate depths continuously from the late Albian-Cenomanian to the late Maastrichtian with a brief interruption during OAE 2. The ~6 to 8 ?Nd unit peak at Demerara Rise during OAE 2 suggests DIW may have shut down over this interval, possibly due to an enhanced hydrologic cycle. Apparently this local bottom water source mixed with or was replaced by water from the larger North Atlantic circulation system. Widespread distribution of positive ?Nd shifts during OAE 2 throughout the North Atlantic implies OAE 2 formation was associated with a basin-wide process such as 1) hydrothermal input of Nd associated with the formation of the Caribbean LIP and/or 2) reorganization of deep oceanic circulation. Yet, Nd isotopic data do not uniquely distinguish between these scenarios and further analyzes are required. General Late Cretaceous circulation patterns based on the distribution of ?Nd data indicate that the Tethys Seaway was the major source of deep water in the North Atlantic during the Albian and Cenomanian. Neodymium values in the western North Atlantic represent a mixture of less radiogenic Tethys and more radiogenic Pacific waters and argue against sluggish conditions. Nd and oxygen isotopic data support the initial opening of the Equatorial Atlantic Gateway between the North and South Atlantic in the Turonian-Santonian that allowed the introduction of cooler, South Atlantic deep waters with ?Nd values of ~-9. Finally, ?Nd values at Demerara Rise shift from unique non-radiogenic background values to more Atlantic-like values in the mid to late Maastrichtian suggesting the end of conditions necessary for formation of the DIW.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Elodie Bourbon.
Thesis: Thesis (M.S.)--University of Florida, 2008.
Local: Adviser: Martin, Ellen E.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2010-08-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2008
System ID: UFE0022706:00001


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NEODYMIUM ISOTOPES THROUGHOUT THE NORTH ATLANTIC IN THE LATE
CRETACEOUS AND ACROSS THE OCEANIC ANOXIC EVENT 2





















By

ELODIE BOURBON


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2008


































(D2008 tlodiefBourbon


































To my parents, Johan, Thomas and Nala.









ACKNOWLEDGMENTS

I would like to sincerely thank Dr. Ellen Martin for her continued guidance on this project.

She is a great mentor, a pleasure to work with and a good friend. I would also like to thanks my

committee members Dr. David Hodell, Dr. George Kamenov and Dr. Philip Neuhoff for their

advice and review of this thesis. Thanks also to Dr. Kenneth MacLeod and Dr. Alvaro Jimenez

Berocosso from the University of Missouri for their advice and review of this thesis as well as

for providing some of the samples. I would also like to thanks Brian Huber for providing some of

the Blake Nose samples.

I am also very grateful for the financial support that was provided by the NSF SGR grant

awarded to Dr. Ellen Martin, the Department of Geological Sciences, and Graduate Student

Council.

Special thanks go to Derrick Newkirk and Chandranath Basak for their guidance and

continuous help in the lab at the beginning of my graduate career. I would like to thank Dr.

George Kamenov for his assistance in the lab and help with analysis and the many others who

have helped me in the laboratory.

Finally, I would like to thank my family and friends. Thanks go to Odile Girod, Christian

Bourbon and to my two brothers Johan and Thomas for their unfaltering love and support.

Thanks go to Joris Barjhoux, Emmanuelle Briche and Emmanuelle Valer for being very

supportive and great friends since elementary and middle schools. Thanks go to Michael Ritorto

for his never ending love, encouragement, and support throughout this process. Thanks go to my

many wonderful friends in the Department of Geological Science at UF, especially Gokge

Atalan, Mary Beth Day, Laura Gregory, Abby Langston, Kelly Probst and Laura Ruhl.









TABLE OF CONTENTS



A C K N O W L E D G M E N T S ..............................................................................................................4

L IST O F T A B L E S ......................................................................................................... ........ .. 7

LIST OF FIGURES ......................................................... ...........................8

A B S T R A C T .......................................................................................................... ..................... 1 1

CHAPTER

1 INTRODUCTION ................................................. ............................. 13

2 BACKGROUND .................... ..................... .. .......... ................................... 18

Archives of Neodymium Isotopes ................... ................19
Late Cretaceous Climate and Paleoceanography..................................................... 21
E quatorial A tlantic G atew ay .......................................... ......................... ................ 22
Albian to Cenomanian ....................... ........... .....................................23
C T B I-S an to n ian .............................................................................................................. 2 4
C am panian-M aastrichtian.. ...................................................................... ................ 25
O ceanic A noxic E vents.................................................... ............................................... 26
Ocean Anoxic Event 2 .......... ............. .. ........... .....................................26
M id-C enom anian E vent... ........................................................................ ................ 28
D description of Sam ple Sites.................................................. ............................................ 29
D em erara R ise Transect ................................................. .............. ................ 29
B lake N ose T ransect ............. .. .................. .................. .......................... ............... 31
G oban Spur T ransect ............... .. .................. .................. ...................... ..................33
B e rm u d a R ise ................................................................................................................. 3 5
C a p e V e rd e ......................................................................................................................3 6

3 M A TERIAL S AN D M ETH OD S .......................................... ......................... ................ 45

Sam ples P reparation .................. .. .................. ................ ................ .. ....... ... ........ ........... 45
Fossil Fish Teeth and D ebris Preparation................................................... ................ 45
Ferrom anganese Oxide Coating Preparation.............................................. ................ 45
Silicate R esidues Preparation .................. ............................................................. 47
Columns Chemistry ................................................ ........................... 47
Neodymium Analysis .............................. .. ........... .....................................48
Strontium Analysis ...... .......... ........................ ......... .. .... ........... .............. 49
Rare Earth Elements Analyses of Fossil Fish Teeth and Fe-Mn Oxide Coatings...............49
M ajor Elements Analyses of Fe-M n Oxide Coatings........................................ ................ 50









4 R E S U L T S ............................................................................................................................... 5 2

Neodymium Results................................. .. ........... .....................................52
D em erara R ise Transect ................................................. .............. ................ 52
B lake N ose Transect ............. .. .................. .................. .......................... ............... 54
G oban Spur Transect ............... .. ................ .................... .....................................55
B erm uda R ise .............. ........................................................................ . ..... 57
C a p e V e rd e ......................................................................................................................5 8
R are E arth E lem ents P lots .............. .................................................................... 58
Sequential Extraction R results ...................... ................................................................ 59
Major Elements Ratios ............................... .. ........60

5 D IS C U S S IO N ....................................................................................................................... 1 12

S e aw a te r S ig n a l ....................................................................................................................1 12
D e m e ra ra R i se ......................................................................................................................1 14
O cean A noxic E vent 2 .......................................................................................................... 115
Implication for the Cause of OAE 2............ ......... ..................116
1. C continental sources .......................................................................................116
2. Caribbean large igneous province ............ ......................117
3. O ceanic circulation ....................................................................................... 119
Late Cretaceous North Atlantic Circulation ....... ... ....... ..................122
Late A ptian-C enom anian .........................................................................................122
T u ro n ia n ........................................................................................................................1 2 4
C o n iacian -S an to n ian ......................................................................................................12 4
Cam panian-M aastrichtian ........................................................................................124

6 CON CLU SION S .............. ........................................................................ . ..... 132

L IS T O F R E F E R E N C E S .............................................................................................................13 5

B IO G R A P H IC A L SK E T C H .......................................................................................................147




















6









LIST OF TABLES


Table page

3-1 Average of 147Sm/144Nd measured at the different sites. .............................. ................ 51

4-1 Demerara Rise Nd isotopic values from Fossil Fish Teeth from ODP Sites 1258,
12 6 0 a n d 12 6 1 ................................................................................................................. ... 6 2

4-2 Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site
1258 at Demerara Rise ................... .. ........... .......................................73

4-3 Blake Nose Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings
from O D P Sites 1049, 1050 and 1052 .......................................................... ................ 75

4-4 Goban Spur Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings
from O D P Sites 549, 550 and 551 ..................................... ....................... ................ 83

4-5 Bermuda Rise Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide
C oatings from O D P Site 386 .................................................................. ................ 89

4-6 Cape Verde Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings
from O D P S ite 3 6 7 ............................................................................................................. 9 3

4-7 REE values extracted from Fe-Mn oxide samples and normalized to PAAS from
USGS Standards and ODP Site 367, 386, 550, 1049, 1050, 1052, 1258 and 1260...........96

4-8 REE values of uncleaned fossil fish teeth normalized to PAAS from ODP Site 367,
3 8 6 a n d 12 6 0 ................................................................................................................. ... 1 0 1

4-9 Nd and Sr isotopic values from fossil fish teeth and Fe-Mn oxide coatings and
residual fraction from ODP Site 1260 at Demerara Rise...................... ...................105

4-10 REE values of Fe-Mn oxide coatings and residual fraction normalized to PAAS from
O D P Site 1260 at D em erara R ise.................................... ...................... ............... 107

4-11 Major elements rations of Fe-Mn oxide coatings from Sites 367, 386, 550, 1049 and
10 52 .............................................................................................. ......... 10 9

4-12 Major elements rations of fish teeth/debris from Sites 549, 1050, 1052, 1260 and
126 1 ......................................................................................... ................... . .......... 111









LIST OF FIGURES


Figure page

2-1. Summary of major geochemical, tectonic and sea level associated with mid-Cretaceous
oceanic anoxic events (O A E s) .......................................... ......................... ................ 38

2-2 Plate reconstruction: 80 M a ................................................................... ................ 39

2-3 Compilation of global benthic foraminiferal 613C and 6180 record based on data from
th e L ate C retaceou s.................................................... ............................................... 4 0

2-4 Present-day locations of ODP and DSDP study sites...................................................41

2-5 Paleogeographic map indicating the estimated location of the study sites in a plate
tectonic reconstruction generated for the CTBI............................................ ................ 41

2-6 Location of ODP Leg 207 sites on Demerara Rise with modem bathymetry ................42

2-7 Stratigraphic range of the Late Cretaceous sedimentary succession and major breaks
in sedim entation of Sites 1258, 1260 and 1261 ............................................ ................ 42

2-8 Location of the ODP Leg 171B drilling transect on Blake Nose .................................43

2-9 Interpretation of seismologic section for Blake Nose, Leg 171B.................................43

2-10 Geologic section across Goban Spur showing the sites drilled during Leg 80...............44

2-11 L location of Site 367, D SD P L eg 41 ............................................................. ................ 44

4-1 SNd(t) values plotted versus meter composite depth (mcd) across the Late Cretaceous
from O D P Sites 1258 at D em erara Rise ....................................................... ................ 66

4-2 SNd(t) values plotted versus meter composite depth (mcd) across the Late Cretaceous
from O D P Sites 1260 at D em erara Rise ....................................................... ................ 67

4-3 SNd(t) values versus depth (mcd) across the Late Cretaceous from ODP Sites 1261 at
D e m e ra ra R ise ................................................................................................................. ... 6 7

4-4 SNd(t) values versus age across the Early Paleogene and Late Cretaceous from ODP
Sites 1258 (3192 m), 1260 (2549 m) and 1261 (1899 m) at Demerara Rise..................68

4-5 SNd(t) values versus age across OAE 2 and MCE from ODP Sites 1258 (3192 m),
1260 (2549 m) and 1261 (1899 m) at Demerara Rise. ................................. ................ 69

4-6 SNd(t) values versus age across OAE 2 from ODP Sites 1258 (3192 m), 1260 (2549 m)
and 1261 (1899 m ) at D em erara R ise ........................................................... ................ 70









4-7 ENd(t) and 613C values versus depth (mcd) across OAE 2 (blue box) and MCE (purple
box) from O D P Site 1260 ................................................................................... 7 1

4-8 High resolution SNd(t) and 613C values versus composite depth across OAE 2 from
O D P Sites 1258, 1260 and 126 1 ........................................ ........................ ................ 72

4-9 Plot of eNd(t) values versus age before, during and after OAE 2 from ODP Site 1258
at D em erara R ise ............................................................................................................... 7 3

4-10 Fe-Mn oxide coating REE patterns from ODP Site 1258 at Demerara Rise..................74

4-11 ODP Sites 1049 at Blake Nose: ENd(t) versus depth (mcd) across the Late Cretaceous. ....79

4-12 ODP Sites 1050 at Blake Nose: ENd(t) versus depth (mcd) across the Late Cretaceous. ....79

4-13 ODP Sites 1052 at Blake Nose: ENd(t) versus depth (mcd) across the Late Cretaceous. ....80

4-14 ENd(t) values versus age (Ma) across the Late Cretaceous and early Cenozoic from
OD P Sites 1049, 1050 and 1052 at Blake N ose............................................ ................ 81

4-15 ENd(t) and 613C of benthic foraminifera (Huber et al., 1999) values versus depth across
OAE 2 from ODP Sitel050 at Blake N ose .................................................. ................ 82

4-16 ODP Site 549 at Goban Spur: ENd(t) values versus depth across the Late Cretaceous........ 86

4-17 ODP Site 550 at Goban Spur: ENd(t) values versus depth across the Late Cretaceous........ 86

4-18 ODP Site 551 at Goban Spur: ENd(t) values versus depth across the Late Cretaceous........ 87

4-19 ENd(t) and 613C (bulk sediment, Gustafsson et al., 2003) values versus depth across
O AE from OD P Site 551 at G oban Spur.. .................................................... ................ 88

4-20 ENd(t) values across the Late Cretaceous from ODP Site 386 at Bermuda Rise .................91

4-21 ENd(t) and 613Corg (MacLeod et al., unpublished data) values across the OAE 2 from
O D P Site 386 at B erm uda R ise.......................................... ........................ ................ 92

4-22 ENd(t) values versus depth across the Late Cretaceous from ODP Site 367 at Cape
V erde ............................................................................................. ....... .. 94

4-23 SNd(t) and 613C values versus depth across the OAE 2 at ODP Site 367 at Cape Verde.....95

4-24 Fe-Mn oxide coating REE patterns from ODP Site 1049 at Blake Nose .......................99

4-25 Fe-Mn oxide coating REE patterns from ODP Site 1050 at Blake Nose.. ..................... 99

4-26 Fe-Mn oxide coating REE patterns from ODP Site 1052 at Blake Nose ..................... 100









4-27 REE plots of the average values from Fe-Mn oxide coatings from ODP Sites 367,
386, 550, 1049, 1050, 1052, 1258 and 1260................ ........................ 100

4-28 Fish teeth REE patterns from ODP Site 367 at Cape Verde................. ...................103

4-29 Fish teeth REE patterns from ODP Site 386 at Bermuda Rise................................103

4-30 Fossil fish teeth REE patterns from ODP Site 1260 at Demerara Rise .........................104

4-31 SNd(0) from fossil fish teeth and Fe-Mn oxide coatings and residual fraction from ODP
Site 1260 at D em erara Rise ................................................................... ............... 106

4-32 87Sr/86Sr values from sequential extraction samples....... ... ..................................... 106

4-33 Fe-Mn oxide coatings REE patterns from ODP Site 1260 at Demerara Rise ...............108

4-34 Silicate residues REE patterns from ODP Site 1260 at Demerara Rise. ........................108

5-1 Compilation of SNd(t) values across the Late Cretaceous in the North Atlantic, Pacific
an d T ethy s...................................................................................................... .......... 12 6

5-2 Pre-OAE 2 SNd values and maximum values reached during OAE 2 at ODP Sites
367, 386, 551, 1050, 1258, 1260 and 1261 ....... ... ......................... 127

5-3A Albian to Cenomanian paleogeographic map of the North Atlantic..............................128

5-3B Cenomanian-Turonian Boundary Interval paleogeographic map of the North
A tlantic .................................................................................................... 129

5-3C Turonian paleogeographic map of the North Atlantic....... .................. .................. 130

5-3D Campanian-Maastrichtian paleogeographic map of the North Atlantic ........................131









Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Sciences

NEODYMIUM ISOTOPES THROUGHOUT THE NORTH ATLANTIC IN THE LATE
CRETACEOUS AND ACROSS THE OCEANIC ANOXIC EVENT 2

By

Elodie Bourbon

August 2008
Chair: Michael R. Perfit
Major: Geology

The Cenomanian/Turonian boundary coincides with the Late Cretaceous thermal

maximum, the formation of the Caribbean Large Igneous Province (LIP) and Oceanic Anoxic

Event 2 (OAE 2), which represents a dramatic perturbation of the global carbon cycle. Late

Cretaceous oceanic circulation in the North Atlantic is poorly known, yet it could be important

for understanding the dynamic conditions that led to OAE 2. Neodymium isotopic compositions

of fossil fish teeth/debris and Fe-Mn oxide coatings from Ocean Drilling Program sites on

Demerara Rise, Blake Nose, Bermuda Rise, Cape Verde and Goban Spur were used to

reconstruct the evolution of North Atlantic deep ocean circulation in the Late Cretaceous and

investigate the relationship between ocean circulation and the formation of OAE 2.

All of the sites with positive 613C excursions at OAE 2 also record a positive SNd shift,

which varies from -1 to 8 SNd units depending on the completeness of the record. Extractions of

Nd from dispersed Fe-Mn oxide coatings from samples before, during and after the excursion

yield ENd values that are consistent with data from fish teeth apatite, indicating that both mineral

phases are robust archives for Nd isotopes in a range of lithologies and redox conditions. Non-

radiogenic SNd values ranging from -14 to -17.5 and a lack of stratification in SNd observed at the

Demerara Rise depth transect sites suggest local ventilation of warm, saline water, referred as to









the Demerara intermediate water (DIW), to intermediate depths. This water mass appears to

have delivered a very non-radiogenic FNd signal, presumably from a local riverine source

draining from the Guyana Shield, to intermediate depths continuously from the late Albian-

Cenomanian to the late Maastrichtian with a brief interruption during OAE 2. The ~6 to 8 FNd

unit peak at Demerara Rise during OAE 2 suggests DIW may have shut down over this interval,

possibly due to an enhanced hydrologic cycle. Apparently this local bottom water source mixed

with or was replaced by water from the larger North Atlantic circulation system. Widespread

distribution of positive SNd shifts during OAE 2 throughout the North Atlantic implies OAE 2

formation was associated with a basin-wide process such as 1) hydrothermal input of Nd

associated with the formation of the Caribbean LIP and/or 2) reorganization of deep oceanic

circulation. Yet, Nd isotopic data do not uniquely distinguish between these scenarios and further

analyzes are required.

General Late Cretaceous circulation patterns based on the distribution of sNd data indicate

that the Tethys Seaway was the major source of deep water in the North Atlantic during the

Albian and Cenomanian. Neodymium values in the western North Atlantic represent a mixture of

less radiogenic Tethys and more radiogenic Pacific waters and argue against sluggish conditions.

Nd and oxygen isotopic data support the initial opening of the Equatorial Atlantic Gateway

between the North and South Atlantic in the Turonian-Santonian that allowed the introduction of

cooler, South Atlantic deep waters with SNd values of --9. Finally, SNd values at Demerara Rise

shift from unique non-radiogenic background values to more Atlantic-like values in the mid to

late Maastrichtian suggesting the end of conditions necessary for formation of the DIW.









CHAPTER 1
INTRODUCTION

The Late Cretaceous was the warmest greenhouse interval in the last 150 Ma (Jenkyns et

al. 1994) and included major perturbations to the global carbon cycle referred to as oceanic

anoxic events (OAEs). OAEs are characterized by large-scale burial of organic carbon, positive

613C excursions in organic and carbonate carbon and widespread deposition of laminated black

shales (e.g., Schlanger and Jenkyns, 1976; Arthur et al., 1987). Evidence for deep sea and surface

anoxia/dysoxia also includes biotic extinctions (e.g., Huber et al., 2002) and the discovery of

biomarkers from green sulfur bacteria during several OAEs (Kuypers et al., 2004). The most

prominent and widespread of Late Cretaceous OAEs is OAE 2, which occurred at the

Cenomanian-Turonian boundary (Schlanger and Jenkyns, 1976; Jenkyns, 1980, Arthur et al.,

1988), a time that coincides with the peak of the Cretaceous greenhouse climate (e.g., Frakes,

1994; Huber et al., 2002; Wilson et al., 2002), emplacement of the Caribbean large igneous

province (LIP) (e.g., Sinton and Duncan, 1997), and a sea level highstand (Haq et al., 1988). The

cause of OAE 2 is still debated with interpretations ranging from surface processes that

generated enhanced surface productivity and decay of the resulting organic matter to deep

processes, such as stagnant circulation and reduced ventilation that produced warm, oxygen

depleted bottom waters. Yet, data on Late Cretaceous intermediate and bottom water circulation

in the North Atlantic, which could potentially discriminate between these two mechanisms, is

lacking.

Neodymium isotopes provide a way to track water masses and paleocirculation patterns

(Frank, 2002; Goldstein and Hemming, 2003) and could be use to evaluate whether or not OAE

2 was associated with changes in deep ocean circulation, and to constrain Late Cretaceous deep

water circulation in general. The residence time of Nd in seawater is about 1000 years (Jeandel et









al., 1995), which is shorter than the mixing time of the oceans (-1500 yrs) (Goldstein and

Hemming, 2003). Neodymium is mainly supplied to the oceans via continental weathering and

runoff of dissolved and particulate fluxes (Bertram and Elderfield, 1993; Frank, 2002; Goldstein

and Hemming, 2003). As a result, Nd isotopes are quasi-conservative tracers of water mass that

reflect the initial signal of the source region and are only slightly modified by weathering inputs

along the flow path. Different oceanic basins have a characteristic SNd (ENd =

[(43Nd/144Nd)sample/( 143Nd/144Nd)CHUR- ] x 104 expressed in s-units) isotopic signature depending

on the surrounding terrains. Within a basin, SNd values also vary vertically within the water

column recording different water masses (Piepgras and Wasserburg, 1987; Bertram and

Elderfield, 1993, Jeandel et al., 1995; Goldstein and Hemming, 2003). Neodymium isotopes are

found in fossils fish teeth/debris and Fe-Mn oxide coatings acquire the SNd signature of the

surrounding water during the early diagenesis (Elderfield and Pagett, 1987; Martin and Scher

2004; Haley et al., 2004; Gutjahr et al., 2007). Thus, Nd contained in these two phases offers an

effective means to track bottom water circulation.

Initial results from a study of Nd isotopes on Late Cretaceous fossil fish teeth/debris from

Demerara Rise, a tropical site in the North Atlantic, revealed a dramatic SNd excursion that

coincides with OAE 2 (Blair, 2006) as defined by 613C (Erbacher et al., 2005). Blair (2006)

documented very non-radiogenic SNd values (-14 to -16) on Demerara Rise in the Late

Cretaceous that increased dramatically to -8 SNd units during OAE 2 before returning to the pre-

OAE 2 values. In contrast, western North Atlantic values for the same time interval ranged from

-5 to -8.5 for the Late Cretaceous (Blair, 2006); Central Pacific values ranged from -2.5 to -5.5

(Frank et al., 2005, Blair, 2006) and Tethys values ranged from -6 to -11.5 (Stille et al., 1990;

Soudry et al., 2006; Puceat et al., 2005). The non-radiogenic values observed at Demerara Rise









are also much lower than any values reported for major Cenozoic water masses, which range

from -3 in the Pacific to -13.5 in the North Atlantic (e.g. Burton et al., 1997, 1999; Frank, 2002;

Scher and Martin, 2004). Blair (2006) proposed that these unique values might reflect inputs

from local sources, such as the neighboring Trans-Amazonian Proterozoic Shield or the Archean

Guiana Highland.

The pilot study by Blair (2006) also tested the integrity of Nd isotopic analyses on fossil

fish teeth and Fe-Mn oxide coatings using Sr isotopes and rare earth elements (REE). Blair

(2006) demonstrated that Fe-Mn oxide coatings extracted from marine sediments are

representative of the deep seawater composition rather than diagenetic alteration, and are

effective archives of deep sea Nd isotopes on Cenozoic to Cretaceous timescales. Thus, the

correlation between the Nd and carbon isotopes suggested that changes in Nd, such as

introduction of a new source of Nd or a distinct deep water circulation pattern coincided with the

formation of OAE 2. Proposed mechanisms for OAE 2 that were consistent with the FNd data

from the Oceanic Drilling Program (ODP) Site 1258 at Demerara Rise include: 1) a change in

the intensity or composition of continental input, 2) eruption of the Caribbean LIP, and 3)

enhanced oceanic circulation and upwelling (MacLeod et al., submitted). Each of these

interpretations provided testable predictions about the distribution of sNd through time and space

in the Late Cretaceous.

In terms of weathering input, the seawater Nd signal at Demerara Rise could change

without a circulation change if the quantity or the composition of the weathered material

changed, introducing a new source of Nd with less radiogenic values to the system (MacLeod et

al., submitted). This change would need to occur relatively rapidly and to be reversible, which

does not seem to reconcile with the time scale of continental weathering. Enhanced weathering









would be accompanied by an increasing nutrient flux to the ocean, promoting surface

productivity, and thus leading to anoxia (Erbacher, 2004). In this model, we should obtain

different SNd responses at different locations depending on the geology of the surrounding

terrains. Also, we would expect to see a negative rather than positive shift associated with

weathering inputs at Demerara Rise since the local inputs have non-radiogenic SNd values.

The timing of the eruption of the Caribbean LIP, which was one of the major LIP events

for that period, coincided with the Cenomanian-Turonian boundary (Alvarado et al., 1997;

Sinton et al, 1998; Hauff et al. 2000). Sinton and Duncan (1997) suggested that surface water

fertilization by metal-rich buoyant hydrothermal plumes related to the Caribbean LIP event

created a bloom of surface productivity. Oxidation of this organic matter and of reduced species

from the hydrothermal effluent could have depleted the oceanic oxygen reservoir. Hydrothermal

circulation through this basaltic province also might have introduced radiogenic Nd into the

ocean. In today's oceans Nd released by hydrothermal vents is quantitatively removed by oxide

formation at the ridge (e. g. Halliday et al., 1992 and Sinton and Duncan, 1997). However, under

anoxic conditions, radiogenic Nd from the LIPs may have been transported farther away. This

scenario would imply that the anoxia, defined by the 613C shift, would need to occur prior to SNd

shift in order to allow the transport of the Nd signal away from the LIP. In addition, similar

positive shifts should occur throughout the North Atlantic, possibly with decreasing magnitude

with distance from the Caribbean LIP.

The enhanced circulation hypothesis is based on the convergence of Demerara Rise FNd

values with SNd values in the western North Atlantic and Tethys (Blair, 2006; Puceat et al., 2005;

Soudry et al., 2006) during the OAE 2 peak, suggesting that the deep ocean was involved in the

formation of OAE 2, but that enhanced circulation, rather than stagnation accompanied the event









(Blair, 2006). Thus, a change in intermediate and deep water sources or water masses mixing

could have occurred at that time. Wind-driven upwelling would increase the nutrient flux to the

surface, promoting productivity and thus anoxia. However, mechanisms that would lead to the

change in circulation and the link between productivity and deep circulation are not completely

understood yet. If enhanced mixing between the DIW and the North Atlantic water mass

occurred, other North Atlantic sites would be expected to shift toward less radiogenic SNd values

during OAE 2. In contrast, if the Nd shift at Demerara Rise results from the removal of the non-

radiogenic source, other North Atlantic sites might not display a Nd shift associated with the

event (MacLeod et al., submitted).

Documented changes in Nd isotopes at Demerara Rise indicate that deep circulation played

a role in the development of OAE 2, but additional data are needed to evaluate overall circulation

patterns in the North Atlantic throughout the Late Cretaceous and determine how deep

circulation impacted conditions during OAE 2. This study compiled Late Cretaceous SNd data of

fossil fish teeth/debris and Fe-Mn oxide coatings from additional Demerara Rise ODP Sites and

several other ODP Sites throughout the North Atlantic, two other depth transects from upper

bathyal to abyssal depths at Blake Nose and Goban Spur, and two deep sites at Bermuda Rise

and Cape Verde. These data are then used to evaluate each of the scenarios for OAE 2 described

above and to develop an understanding of basic intermediate and deep water circulation patterns

through the Late Cretaceous in the North Atlantic.









CHAPTER 2
BACKGROUND

Neodymium is a light Rare Earth Element (REE). It has seven stable isotopes. Radiogenic

143Nd is produced by the alpha decay of 147Sm which has a half life of -1.06 x 10-11 years. Hence,

the abundance of 143Nd and the ratio of 143Nd/144Nd have increased with time. The relationship

between the measured 143Nd/144Nd and the initial 143Nd/144Nd is described by the following

equation:

143Nd 143Nd 147Sm
44Nd 144 Nd) + 44 (e 1)

121/d d/ Nd
with = 6.54 x 10-12 y-1. The isotopic evolution of Nd on Earth is described by the "Chondritic

Uniform Resevoir" (CHUR) model (DePaolo and Wasserburg, 1976a). It is possible to calculate

143Nd/144Nd of CHUR at any time in the past:

t o 0 (147SmA
ICHUR = ICHUR 144 CHUR X (e- 1)


where ItCHUR is the ratio of 143Nd/144Nd at a given time (t), IOCHUR is the present value of

143Nd/144Nd (0.512638) and 147Sm/144Nd is the present value of CHUR based on meteorites

(0.1967). Throughout the thesis, Nd isotopic ratios will be presented using the epsilon notation

(ENd) which expresses Nd isotopes as the deviation from bulk Earth values in part per 104:

(143 /144N
7() measured 1 X 104
'CHUR
(143 /144 10
SNd/ Ndinitial 1 X 104
CHUR

In the long term, Nd is preferentially partitioned into the liquid phase during partial

melting of the mantle; as a result old crustal rocks have a lower 147Sm/144Nd ratio than bulk Earth

and volcanic rocks have a higher 147Sm/144Nd ratio than bulk Earth. This is expressed by a









negative SNd, which varies from 0 to -50. In contrast, a positive SNd indicates that the rocks are

derived from melting of the mantle, such as mid-oceanic ridge and ocean island basalts, which

have FNd values varying from 0 to +12 (Piepgras and Wasserburg, 1980).

Archives of Neodymium Isotopes

The concentration of Nd in seawater is low, ~4pg/g; however, fossil fish remains and

authigenic Fe-Mn oxides concentrate and record seawater values, thereby providing archives that

can be used to track water masses and paleo-circulation patterns. Ferromanganese oxide crusts

and nodules have high Nd concentrations of -100 ppm. Previous studies have shown that Fe-Mn

oxide crusts record deep water Nd values through time (Albarede and Goldstein, 1992;

Abouchami et al., 1997; Burton and Ling, 1997; Frank and O'Nions, 1998, Frank et al., 2002;

Van de Fierdt et al., 2004; Gutjahr et al., 2007). Fe-Mn crusts have been used to compile records

of long-term trends and variations in ocean circulation over much of the Cenozoic. However,

their growth rate is quite slow, ranging from 1 to 15 mm/Ma (Segl et al., 1984; Puteanus and

Halback, 1988); thus, these archives produce a low resolution record of changes through time,

and rapid shifts in circulation potentially associated with climatic events may not be preserved.

These crusts are typically dated using Be isotopes, which is problematic for samples older than

10 Ma because the half-life of 10Be is 1.5 x 106 years. Moreover, crusts have a sparse distribution

and only grow in environments with very slow sedimentation rates, which inhibit high

resolution.

More recently, dispersed authigenic Fe-Mn oxides coatings on marine sediment were

shown to record the contemporaneous seawater composition and thus are suitable for Nd isotopic

analyses (Rutberg et al., 2000; Bayon et al., 2002; Piotrowski et al., 2004; Blair, 2006). These

authigenic coatings are made of the same material that is concentrated in the Fe-Mn crusts and

nodules, but they can be dated with surrounding sediment using biostratigraphic,









magnetostratigraphic and chemostratigraphic techniques. However, they cannot be physically

separated, thus a sequential leaching procedure is required to extract the Nd from the Fe-Mn

oxide fraction (Rutberg et al., 2000; Bayon et al., 2002; Piotrowski et al., 2004; Blair, 2006).

Fish remains are also effective archives for Nd (Staudigel et al., 1985; Elderfield and

Pagett, 1986; Martin and Haley, 2000; Thomas et al., 2003; Martin and Scher 2004; Thomas,

2004; Scher and Martin, 2006). Although the hydroxyapatite teeth of living fish contain a few

ppb of Nd, the hydroxyfluorapatite of fossil fish teeth contain between 100 and 1000 ppm Nd.

(Wright et al., 1984; Shaw and Wasserburg, 1985; Staudigel et al., 1985; Martin et al., 1995,

Martin and Haley, 2000; Martin and Scher, 2004). This Nd is incorporated into fossil fish

remains during early diagenesis when they are often still in contact with deep ocean water

(Elderfield and Pagett, 1986; Martin and Scher 2004). Fossil teeth are found in all ocean basins

and they record detailed variations in the deep water signal through time. In addition, they can be

dated with the surrounding sediment using biostratigraphic, magnetostratigraphic and

chemostratigraphic techniques.

Several general lines of evidence support the idea that fossil fish remains and Fe-Mn oxide

coatings preserve a record of the deep water signal through time: 1) Fish remains, Fe-Mn oxide

coatings, and crust deposited in similar water masses yield identical isotopic ratios within error

and without any systematic bias (Martin and Haley, 2000; Blair, 2006); 2) teeth exposed to the

same water masses, but in different locations, lithologies and pore fluids record similar isotopic

ratios (Martin and Haley, 2000); 3) the concentration of Nd in the teeth does not systematically

increase with burial depth or age (Bernat, 1975; Staudigel et al., 1985, Martin, unpublished data),

and 4) higher Nd concentrations are observed in teeth exposed to seawater longer because they

were deposited in slow sedimentation areas (Elderfield and Pagett, 1986; Staudigel et al., 1986;









Martin and Scher, 2004). Since Nd is highly reactive, it occurs in extremely low concentrations

in pore fluids. Therefore, very little Nd is available for incorporation or exchange once the

teeth/debris or Fe-Mn oxide coatings are no longer in communication with seawater.

Late Cretaceous Climate and Paleoceanography

The Late Cretaceous was the most intense greenhouse interval in the last 150 Ma (Jenkyns

et al. 1994). This warm climate was characterized by atmospheric CO2 concentrations 3 to 16

times greater than modem levels (Baron and Peterson, 1990, Bice and Norris, 2002; Bice et al.,

2006) and a low equator to pole temperature gradient (Huber et al., 1995; Huber et al., 2002;

Bice et al., 2003, 2006). This interval of time also experienced a worldwide pulse in ocean

crustal production including the emplacement of large igneous provinces (LIPs) in the Caribbean

(Larson, 1991) at the Cenomanian/Turonian boundary interval (CTBI) (Alvarado et al., 1997;

Sinton et al, 1998; Hauff et al. 2000). In response to thermal expansion and crustal production,

global sea level rose to the highest level of the past 250 Ma, peaking in the early to middle

Turonian (Haq et al., 1988) (Figure 2-1). High sea level conditions led to extensive areas of

epicontinental seas, including the Western Interior Seaway in the United States (Hay et al.,

1993).

The North Atlantic was a young growing basin located in tropical to subpolar latitudes

(Figure 2-2). It had evolving connections to Tethys in the east, to the South Atlantic to the south,

and to the Pacific to the west. The conditions necessary for the North Atlantic Deep Water

(NADW) production or formation had not developed yet. Late Cretaceous oceanic circulation

has been modeled (e.g., Barron and Peterson, 1980; Barron et al., 1993, 1995), but is difficult to

constrain. Surface water masses entering the North Atlantic Ocean were derived from the Tethys

Ocean and/or the Pacific Ocean by the Tethyan circumglobal current flowing around the equator









(Stille et al., 1996; Puceat et al., 2005). In contrast, deep circulation in the North Atlantic during

the Late Cretaceous is not well known.

Equatorial Atlantic Gateway

The deep opening of the Equatorial Atlantic Gateway (EAG) between the North and South

Atlantic Ocean basins in the Late Cretaceous caused a major reorganization of deep oceanic

circulation and evolution of benthic and planktic biota. (MacLeod and Huber, 1996; Frank and

Arthur, 1999; Poulsen et al., 2001, 2003; Kuypers et al., 2002; Frank et al., 2005; Isaza-Londono

et al., 2006). However, the exact timing of a deep water connection between the North and South

Atlantic through the EAG is still debated. Paleomagnetic methods only provide limited

constrains because of the low latitude position of the EAG and the lack of magnetic lineation in

the mid Cretaceous.

Estimates for the deep water connection range from in the early Turonian to the early

Campanian (Tucholke and Vogt, 1979; Summerhayes, 1981; Wagner and Pletsch, 1999; Pletsch

et al., 2001; Kuypers et al., 2002). Pletsch et al. (2001) placed the opening of the EAG in the

early Turonian using a complilation of published sedimentologic, mineralogic,

micropalaeontologic and geochemical data from the northern Gulf of Guinea. In addition, levels

of carbonate saturation were different among different oceanic basins in the Albian, but they

converged near the CTBI (Arthur et al., 1985), which might reflect greater connection between

basins. Proponents of this earlier opening argue that erosive deepwater currents created by the

exchange between North and South Atlantic basins caused widespread hiatuses observed in

Atlantic sections, including many of the sites studied in this project (Wagner and Pletsch, 1999).

Coupled ocean-atmosphere model simulations also suggest oceanographic changes related to the

gateway event that could have contributed to the development of the Cretaceous thermal

maximum at the CTBI (Poulsen et al., 2001, 2003).









Friedrich et al. (2007) compiled published Late Cretaceous 6180 data from the North and

South Atlantic, Pacific, Indian and Southern Oceans (Figure 2-3) that appears to indicate that

deep opening of the EAG started in the Turonian (-90 Ma) and was completed by the late

Santonian to Campanian (-84 Ma). They suggested that the general cooling trend from the late

Turonian to Campanian is related to the opening of the EAG and to reorganization of oceanic

deep circulation. The EAG was fully opened in the early Campanian, introducing oxygenated

deep waters into the North Atlantic that resulted in the transition from black shales to oxygenated

chalk observed at Demerara Rise.

In contrast, Frank et al. (1999) suggest that the deep circulation between the North and

South Atlantic is linked to the subsidence of the Rio Grande-Walvis Ridge in the mid Campanian

to late Maastrichtian. They propose that the deep opening of the EAG contributed to the latest

Cretaceous global cooling trend by exporting cool intermediate and deep water from the

Southern Ocean into the North Atlantic.

Albian to Cenomanian

Throughout the late Albian to mid Cenomanian, paleotemperature estimates for middle

bathyal water masses average 160C, and tropical to subtropical sea surface temperatures (SST)

ranged from 26 to 310C (Huber et al., 2002; Petrizzo et al., 2008). This period of time was

associated with changes in the vertical stratification of the water column in the western North

Atlantic, moderately low latitudinal thermal gradients and a potential transition from oligotrophic

to mesotrophic conditions (Wilson and Norris, 2001; Erbacher et al., 2001; Huber et al., 2002;

Petrizzo et al., 2008). At Blake Nose, intervals of high SST correspond to periods of strong

vertical stratification, whereas cooler SSTs correspond to intervals of weaker stratification

(Wilson and Norris, 2001; Petrizzo et al., 2008). In the South Atlantic deep water formation

occurred predominantly in the southern high latitudes (Schmidt and Mysak, 1996; Poulsen et al.,









2001). There is evidence that deep water formation occurred in subtropical regions of the North

Atlantic where excessive evaporation led to sinking of warm, saline waters (Brass et al., 1982;

Arthur et al., 1985, 1987; Barron and Peterson, 1990; Woo et al., 1992; Barron et al; 1993;

Mosher et al., 2007).

CTBI-Santonian

A gradual transition to a hot greenhouse climate started in the mid Cenomanian and

reached a maximum at the CTBI that represents the Cretaceous Thermal Maximum (Frakes,

1994; Huber et al., 2002; Wilson et al., 2002; Gustafsson et al., 2003; Forster et al., 2007).

Bottom waters temperature reached an average of 190C at high latitude and low latitudes sites

and stayed as high as ~170C from the Coniacian to mid Campanian. Estimates for SST range

from 31 to 420C in the tropical western Atlantic Ocean during the late Cenomanian to early

Turonian (Bice et al., 2006; Forster et al., 2007). The thermocline was poorly developed in the

western North Atlantic and surface waters were strongly mixed from the early Cenomanian to

mid Campanian (Huber et al., 2002). Bottom waters likely formed at high latitudes in the Pacific

and Southern Ocean (Bice and Marotzke, 2001; Schmidt and Mysak, 1996; Poulsen et al., 2001).

Decreased 6180 values of benthic foraminifers in the late Cenomanian indicate that bottom water

salinity decreased and/or that bottom water temperatures increased (Friedrich et al., 2006).

Changes in salinity could have been related to increased precipitation associated with an

accelerated hydrological cycle at the CTBI (Calvert and Pederson, 1990; Erbacher and Thurow,

1997). Associated enhanced freshwater runoff would have reduced deepwater production in low

latitudes (Mosher et al., 2007, MacLeod et al., submitted). In contrast, other researchers have

suggested that conditions including high latitude warm bottom waters and maximum flooding of

epicontinental seas were favorable for warm saline deep water formation at low latitudes at the

CTBI (Arthur et al., 1987; Huber et al., 2002). Warm saline deep water formation would have









led to increased rates of oceanic turnover, upwelling of nutrient-rich deep water and subsequent

increased sea surface productivity (Arthur et al., 1987).

Seawater Sr isotopes (Mc Arthur et al., 2001, Jones and Jenkyns, 2001) and Mg/Ca ratio

(Bice et al., 2006) were both at a minimum from the Turonian to the Coniacian, which might

coincide with a maximum rate of seawater exchange through hydrothermal systems associated

with the Caribbean LIPs (Jones and Jenkyns, 2001, Bice et al., 2006). The most precise 40Ar/39Ar

dates for the Caribbean LIPs range from 87-95 Ma (Alvarado et al., 1997; Sinton et al, 1998;

Hauff et al. 2000).

Campanian-Maastrichtian

Bottom water dropped below 120C by the middle Campanian and to a minimum of 90C in

the Maastrichtian in the western North Atlantic and low latitude SSTs were 8 to 100C cooler than

modern values of 160C (Huber et al., 2002). The Maastrichtian is characterized by a general

cooling trend and major eustatic regressions which probably resulted in changes in deep water

circulation (Haq et al., 1988). This global cooling triggered an extinction event prior to the K/T

boundary, increased latitudinal thermal gradients and increase ventilation of the deep ocean

(MacLeod and Huber, 1996; Frank and Arthur, 1999; Frank et al., 2005). Intermediate and deep

cool water masses were forming in high latitudes Southern Ocean, in the North Pacific and

potentially in the North Atlantic (MacLeod and Huber, 1996; Poulsen et al., 2001, Bererra and

Sarvin, 1999; Friedrich et al., 2004; Frank et al., 2005; Isaza-Londono et al., 2006). MacLeod et

al. (2005) proposed that intensification of the North Atlantic polar front reduced oceanic and

atmospheric heat transport into the Arctic, leading to Arctic cooling and reinforcing North

Atlantic downwelling. During the last 3 Ma of the Maastrichtian intermediate and surface waters

temperatures increased between 2 to 60C (Bererra and Sarvin, 1999; Isaza-Londono et al., 2006).









This warming may be the result of heat imported from the South Atlantic as a surface current in

order to replace the sinking water in the North Atlantic (Isaza-Londono et al., 2006).

Oceanic Anoxic Events

The Late Cretaceous also included major perturbations of the global carbon cycle during a

series of oceanic anoxic events (OAEs) characterized by widespread deposition of organic-

carbon rich marine sediments with positive or negative 613C excursions (e.g., Schlanger and

Jenkyns., 1976; Arthur et al., 1990). These events represent relatively brief periods of time

(Sageman et al., 2006) and must have been caused by large scale changes to the ocean

environment and chemistry. At least six events have been described (OAE la-d, OAE 2, and

OAE 3), two of which (the Selli event/OAE la and the Bonarelli event/OAE 2) are global

(Figure 2-1). OAEs are lithostratigraphically defined by the deposition of laminated carbon-rich

sediments in environments ranging from deep ocean to shelf seas and typically

chemostratigraphically defined by positive stable carbon isotope excursions. Organic carbon is

depleted in 13C relative to inorganic carbon. Thus, enhanced burial of organic carbon results in

an increase in 613C in inorganic carbon, as well as sequestration of atmospheric carbon (Arthur et

al., 1988; Kuypers et al., 1999). Late Cretaceous OAEs also coincide with short-term Sr isotope

excursions to lower 87Sr/86Sr associated with the formation of LIPs (Jones and Jenkyns, 2001).

Major OAEs are believed to create a negative feedback to greenhouse conditions, such that

burial of organic carbon could lead to C02 sequestration and global cooling (Arthur et al., 1988;

Jenkyns et al., 1994).

Ocean Anoxic Event 2

The CTBI is associated with OAE 2, also known as the Bonarelli Event (Schlanger et al,

1987). OAE 2 represents an extreme interval of organic carbon burial. Evidence for deep sea

anoxia at that time includes the high organic carbon content and laminated sediments that were









worldwide deposited in a range of marine setting, including shallow shelf and deep sea

environments. The distribution of green sulfur bacteria, which are obligate anaerobic autotrophs,

during OAE 2 indicates that anoxic condition extended into the photic zone for at least short

intervals of time in the North Atlantic (Kuypers et al., 2004). The CTBI is stratigraphically

defined by a positive 613C excursion up to 6 %o in organic carbon (Erbacher et al., 2005; Forster

et al., 2007; MacLeod, Unpublished data) and up to 2 %o in carbonate carbon (Huber et al., 1999;

Gustafsson et al., 2003). At the time of the carbon excursion a dramatic change in the planktic

foraminifer assemblage occurred with the extinction of many deeper dwelling foraminifera and

radiolarians (Rotalipora spp., Globigerinelloites bentonensis) (Huber et al., 1999). OAE 2 black

shales have been described from numerous outcrops and deep-sea cores around the world, which

makes the CTBI well-suited for micropaleontological and chemostratigraphical correlation

between cores (Arthur et al., 1988; Paul et al, 1999; Kuypers et al., 2002; Gustafsson et al., 2003;

Erbacher et al., 2005, Sageman et al., 2006; Hardas and Matterlose, 2006; Forster et al., 2007).

The mechanisms for the formation of OAE 2 have been widely debated with interpretations

ranging from a top down model relying on enhanced surface productivity, to a bottom up model

that relies on anoxic deep waters.

In the top down model, enhanced surface productivity due to increasing upwelling and/or

terrestrial nutrient input leads to bottom water anoxia through the decay of organic matter in the

deep ocean (Erbacher et al., 2004). Proposed acceleration of the hydrological cycle could have

increased continental runoff of nutrients (Calvert and Pederson, 1990; Erbacher and Thurow,

1997). Another mechanism that can lead to anoxia by the top down model is the eruption of the

Caribbean LIP and high oceanic crustal production rates. Sinton and Duncan (1997) proposed

that increased hydrothermal activity associated with this volcanism could have introduced large









quantities of C02, SO02, H2S, halogens and trace metals into the oceans, potentially stimulating

primary surface production by releasing Fe in the form of dissolved metals into surface water.

This hypothesis is supported by high abundances of trace metals that were found in marls and

organic-rich sediments in the southern WIS corresponding with the onset of the 613C peak (Orth

el al., 1993; Snow et al., 2005). The strongest signals are found in the south central and southern

region of the WIS, but decrease gradually to the east and west. The enhanced organic rain rate

fueled by biolimiting metals could have exceeded the capacity of the deep ocean to oxidize

organic material, leading to anoxia in the water column, extinction of some bottom dwelling

organisms and deposition of the black shales. Oxidation of the sulfides and reduced metals

released by hydrothermal effluents would have also consumed dissolved oxygen from seawater.

Volcanic eruptions at that time produced at least 1000 times more material than ridge volcanism

today and estimates are that oxidation of this material would have consumed about 6% of the

seawater oxygen (Sinton et Duncan, 1997).

In the bottom up model, enhanced preservation of the organic matter and anoxia in the

deep sea is caused by decreased dissolved oxygen in oceans and reduced oxidizing capacity of

bottom water. Specifically, deep water anoxia could be generated by warmer intermediate and

deep waters and more stagnant conditions created by decreased bottom water ventilation due to

morphological barriers, density stratification, or reduced latitudinal SST gradients (Schlanger

and Jenkyns., 1976).

Mid-Cenomanian Event

Two million years prior to OAE 2, a smaller precursor event occurred, which is referred to

as the Mid Cenomanian Event (MCE) (Coccioni and Galeotti, 2003). This event is associated

with large-scale changes in oceanic structure and climate prior to the Bonarelli event (Coccioni

and Galeotti, 2003). Black shale deposition during the MCE was not as widespread as during









OAE 2, but organic-rich facies can be found in the North Atlantic, (Demerara Rise-Moriya et al.,

2007; MacLeod et al., unpublished) and Tethys (Jenkyns, 1994; Coccioni and Galeotti, 2003).

The MCE is also associated with a ~4 %o positive shift in 613Corg (MacLeod et al., unpublished)

, a reorganization of planktonic and benthic foraminiferal assemblages and a positive shift in the

Sr/Ca ratio of carbonates due to changes in calcareous nannofossil productivity (Stoll and

Schrag, 2001). The oxygen isotopic record indicates that the warming trend started with the

MCE before reaching its maximum during OAE 2 (Coccioni and Galeotti, 2003). Unlike OAE 2,

MCE occurred during a major sea level regression. Modifications of planktonic and benthic

foraminifera assemblages indicate a weakening of the thermocline and an increase of water

mixing (Premoli Silva and Sliter, 1999), expansion of warm water into high latitudes, and a

decrease in bottom water oxygen levels (Coccioni and Galeotti, 2003).

Description of Sample Sites

Demerara Rise Transect

Sites 1258, 1260 and 1261 were drilled on Demerara Rise during the Oceanic Drilling

Program (ODP) Leg 207 (Shipboard Scientific Party, 2004 a, b, c). These sites are located ~5N

latitude off Suriname and French Guyana in South America (Figures 2-4 and 2-5) forming a SE-

NW paleoceanographic depth transect on Demerara Rise that slopes gently to the northwest

(Figure 2-6). During the Late Cretaceous, these sites were at upper to mid-bathyal depths (200 m

to 1500 m) (MacLeod, personal communication). Cenomanian-Santonian black shales are

separated from Campanian to Oligocene pelagic and hemipelagic chalks and marls by a hiatus

representing -7.5 My (Figure 2-7) (Erbacher et al., 2004 and 2005). OAE 2 is clearly defined at

all three sites by increases in total organic carbon and 6 %o increases in 613C (Erbacher et al.,

2005). In addition, Site 1260 includes the Mid Cenomanian Event (MCE) based on 613C patterns









(MacLeod, personal communication). Fish teeth and debris are abundant throughout the studied

interval.

ODP Site 1258, the deepest site of the depth transect, is located at a modem water depth of

3192 m meters below sea level (mbsl). Samples were collected from 67 to 477.49 mcd in cores A

and B, spanning lithologic sections Units II to IV and representing an age range from the -100 to

50 Ma. Site 1260 is located at a modem water depth of 2549 mbsl. Samples were collected from

341.95 to 502.62 mcd in cores A and B, spanning lithologic Units III to V and representing an

age range of 66-100 Ma. Finally, Site 1261, the shallowest site of the transect, is located at a

water depth of 1899 mbsl. Samples were collected from 546.29 to 647.69 mcd, spanning

lithologic Units III to IV and representing an age range of 70-96 Ma. A hiatus that corresponds to

the absence of the lower Santonian-Campanian sediments is present at the three sites with

slightly different durations at each site.

Lithologic units are similar at all three sites (Figure 2-7): Unit V, the oldest unit recovered

(early Albian; 486.28 to 510.05 mcd at Site 1260 and 480.8 to 483.5 mcd at Site 1258) is

dominated by clayey limestone with quartz and calcareous claystone with quartz and high

organic matter content. Unit IV ranges from 415 to 480.85 mcd (late Albian to Turonian) at Site

1258, from 393 to 486.71 mcd (Cenomanian to Coniacian) at Site 1260 and from -564.5 to

649.73 mcd (late Cenomanian to Santonian) at Site 1261. It is primarily composed of laminated

calcareous organic-rich black shale with interlayered laminated chalk/limestone. Color variations

between these two sediment types correspond to the carbonate content, which ranges from 5-95

weight percent (wt%). OAE 2 occurs within this unit, as defined by 613C (Erbacher et al., 2005).

Sediment accumulation in the previous two units occurred at 3 m/m.y. at Site 1258 and 8.5

m/m.y. at Sites 1260 and 1261. Unit III ranges from 343.46 to 415 mcd (Campanian) at Site









1258, from 275.97 to 393 mcd (late Paleocene to early Campanian) at Site 1260 and from 534.6

to 564.5 mcd (late Paleocene-late Campanian) at Site 1261. It is composed dominantly of

nannofossil chalk with clay and claystone with an average of -20-65 wt% carbonate content.

Sediment accumulation in Unit III occurred at 10-15 m/m.y. at Site 1258, 4-12 m/m.y. at Site

1260 and 3-7 m/m.y. at Site 1261. Unit II was only sampled at Site 1258 where it spans from

8.52 to 343.47 mcd (Eocene to Maastrichtian) and consists of nannofossil and calcareous chalk

with foraminifers with 30 to 80 % carbonate. Sediment accumulation in this unit occurred at 15

m/m.y. at Site 1258, 20 m/m.y. at Site 1260 and 7-9 m/m.y. at Site 1261(Erbacher et al., 2004).

Blake Nose Transect

The Blake Nose sites represent another depth transect off Florida in the western Atlantic

(Figures 2-4, 2-5, 2-8 and 2-9). ODP Sites 1049, 1050 and 1052 (Leg 171) range from -1000 m

to -2700 m modern water depth with estimates for paleodepth ranging from 500 to 1500 m

(Huber et al., 2002; Petrizzio et al., 2008). Sedimentary structures and microfossils are

remarkably well preserved. Site 1050 has an incomplete record of OAE 2, whereas Sites 1049

and 1052 do not contain any records of OAE 2 (Norris et al., 1998; Huber et al., 1999). Sites

1050 and 1052 both contain OAE Id black shales, and Site 1049 contains OAE lb. The deepest

site, Site 1049, is located at a modern water depth of 2671 mbsl. Sediments were deposited at

-1500 m water depth in the Late Cretaceous. Samples were collected from 134-173 mbsf for

Hole A spanning lithologic Units III to IV and from 140 to 154 mbsl for Hole C from lithologic

unit IV. The samples represent an age range of 49-115 Ma. Unit IV (middle Albian to Aptian)

spans from 144.1 to 190.9 mbsf in Hole A and from 132.4 to 153.3 mbsf in Hole C. It is

composed of clayey nannofossil chalk to clay ranging from 20 to 90% carbonate and an organic-

rich black shale representing OAElb (Norris et al., 1998; Erbacher et al., 2001). The

sedimentation rate across this unit is -6 m/m.y. These sediments are separated from Campanian









to early Paleocene sediments of Unit III by a hiatus representing -28 My. Unit III (early

Paleocene to Campanian) spans from 105.3 to 144.3 mbsf in Hole A and is composed of

nannofossils chalk with foraminifera and clay, and a spherule layer representing the K/T

boundary. Sediment accumulation during this interval of time was -3.6 m/m.y.

Site 1050 is located at a water depth of 2300 mbsl. Samples were collected from 174 to

313 mbsf for Hole A from lithologic Units IC to II and from 329 to 605 mbsf for Hole C

spanning from lithologic Units III to VI. The samples represent an age range of 53-102 Ma. Unit

IC (late early Eocene to middle Eocene) is composed of siliceous nannofossil ooze to nannofossil

chalk with siliceous microfossils. Unit VI (late Albian to late Cenomanian) consists of

nannofossil chalk or limestone with variable amounts of clay and claystone with variable

amounts of nannofossils (Norris et al., 1998). The sedimentation rate across this unit is ~6m/m.y.

10 m/m.y. Unit V (late Turonian to late Campanian) spans from 491.4 to 501.7 mbsf in Hole C

and includes a series of hardgrounds from reddened, weakly biotubated chalk to hard, heavily

bored phosphate iron crust. These hardgrounds mark a distinct change in sedimentation style

from the late Cenomanian to the late Campanian. The oldest hardground represents the CTBI but

only the beginning of OAE 2 was recovered, as defined by a positive 613C shift (Huber et al.,

1999). The sediment accumulation rate for this interval is <1.5 m/m.y. A hiatus of -15 My

separates Units IV and V. Unit IV (Campanian to Paleocene) spans from 343.5 to 491.4 mbsf in

Hole C and is composed of calcareous claystone with nannofossils to nannofossil chalk and

limestone and includes the K/T boundary. Sediment accumulation during this interval of time

was -17 m/m.y.The underlying unit, Unit III (early Paleocene), spans from 327.1 to 343.5 mbsf

in Hole C and contains clayey siliceous chalk with nannofossils and chert. The contact between

Units II and III was not recovered. Unit II (early to late Paleocene) spans from 304.9 to 319.9









mbsf in Hole A and is made of diatomaceous nannofossil chalk and nannofossil diatiomite. The

sedimentation rate across the last two units is -15.2 m/m.y.

Site 1052 is the shallowest site of the Blake Nose depth transect. It is located at a modern

water depth of 1345 mbsl. Samples were collected from 37 to 88 mbsf for Hole B from lithologic

Units IC and from 140 to 677 mbsf for Hole E spanning lithologic Units II to V. The samples

represent an age range of 36-104 Ma. Unit V (Cenomanian to late Albian) spans from 343.5 to

491.4 mbsf in Hole 477.4 to 684.8 mbsf and contains dark olive silty claystone, black shale, and

medium to coarse, moderately well- to well-sorted sandstone with 20 to 90 % carbonate. The

OAE 2 is missing at this site. A hiatus of -15 My separates Units IV and V. Sediment

accumulation during this interval of time occurred at -26.2 m/m.y. Unit IV (Maastrichtian) spans

from 301.6 to 477.4 mbsf and is composed of clayey nannofossil chalk with 60 to 90 %

carbonate. The upper contact of the unit is the K/T boundary and the lower contact is the base of

the slump that separates Maastrichtian chalk from Cenomanian limestone with interbedded

siltstone of Unit V. Unit III (early to late Paleocene) spans from 204.0 to 301.6 mbsf and

contains nannofossil claystone with zeolite and nannofossil and foraminifer chalk with 20 to 80

% carbonate. Unit II (middle Eocene to late Paleocene) spans from 140.0 to 204.0 mbsf and

consists of nannofossil chalk and foraminifer chalk with chert layers and calcareous claystone

with 20 to 80 % carbonate (Norris et al., 1998). The sedimentation rate across the last three units

is -21.7 m/m.y. Unit IC (middle Eocene) spans from 26.7 to 119.5 mbsf and contains

nannofossil ooze to siliceous nannofossil ooze with -80 % carbonates. Sediment accumulation

during this interval of time was -18.2 m/m.y.

Goban Spur Transect

Deep Sea Drilling Project (DSDP) Sites 549, 550 and 551 (Leg 80) were drilled on Goban

Spur, southwest of Ireland (Figures 2-4 and 2-5). These sites represent a depth transect from









bathyal to abyssal depths in the northeastern North Atlantic (Figure 2-10). Site 549, the

shallowest site, is located near the edge of Pendragon Escarpment in 2515 meters water depth.

Samples were collected from 247 to 504 mbsf, which represents an age range from mid Eocene

to mid Albian and lithologic Units II to VI. Unit VI spans from 479 to 664.15 mbsf (Albian) and

consists of gray calcareous siltstones with 20 to 80 % carbonate. The sedimentation rate in this

unit is -93 m/m.y. Unit V spans from 426.6 to 479 mbsf (early Cenomanian to early Turonian)

and contains gray and greenish gray nannofossil chalk with 65 to 90 % carbonate. It includes

black carbonaceous shales from 436.2 to 436.53 mbsf in which organic carbon contents range up

to 3.5%. Units IV to II (Turonian to early Cenozoic) span from 198.5 to 426.6 mbsf and are

composed of > 50 m of light-colored to brown nannofossil chalks with -85-95 % carbonate in

Unit IV, 35-65 % in Unit III and 75-97 % in Unit II (De Graciansky et al, 1981; De Graciansky

and Bourbon, 1985). The sedimentation rate for last four units is -3.5-5 m/m.y. for the Upper

Cretaceous and -11 m/m.y. for the Early Cenozoic.

Site 550 is located on the Porcupine Abyssal Plain at 4420 mbsl. Samples were collected

from 357 to 681 mbsf, spanning lithologic sections Units III to V. The samples represent an age

range of 55-108 Ma. Unit V (uppermost Albian to middle Cenomanian) is composed of

alternating carbonaceous and non-carbonaceous siltstones with 40 to 75 % carbonate that were

deposited above the CCD. Unit IV (Coniacian to Santonian) is made of dark claystones

interbedded with turbiditic calcareous mudstones. The carbonate content is low (0 to 10 %),

which suggests that sediments were deposited below the CCD. Unit III (upper Campanian to

lower Paleocene) contains marly nannofossil chalks interbedded with calcareous turbidites and

mudflows with 33 to 95 % carbonates. Site 550 has several unconformities and hiatus between

the middle Cenomanian to Coniacian strata and probably between the Campanian or









Maastrichtian and the Coniacian-Santonian, but carbonate dissolution and poor microfossil

preservation prevented accurate dating of this part of the section. Sedimentation rates were 13.5

m/m.y. for the late Albian-mid Cenomanian, 1 m/m.y. for the mid Cenomanian-lower

Campanian, 17.5 m/m.y. for the Campanian-Maastrichtian and 6.6 m/m.y. for the Paleocene.

Paleobathymetric reconstruction place the site between 2000 and 3000 mbsl for the Late

Cretaceous (De Graciansky et al, 1981; Masson et al., 1985; De Graciansky and Bourbon, 1985).

Site 551, the deepest site (3909 mbsl), is located at the seaward edge of Goban Spur.

Paleodepths range between 1500 to 2000 mbsl for the Late Cretaceous (Masson et al., 1985).

Samples were collected from 107 to 143 mbsf, spanning lithologic Units III to VI and

representing an age range from the Cenomanian to Maastrichtian. Unit VI (late Cenomanian)

spans from 138.5 to 142.4 mbsf and contains light-colored nannofossil chalk with 90 to 95 %

carbonate. The contact between Units V and VI was not recovered. Unit V (early Turonian)

occurs from 134.6 to 138.5 mbsf and consists of black shale mixed with gray and white chalks

with 8 to 11 % carbonate. This unit represents the end of OAE 2, which has been defined by 613C

by Gustafsson et al. (2003). Unit IV (Turonian) ranges from 132.5 to 134.6 and contains white to

pale green nannofossil chalk and siliceous mudstone with 50 to 70 % arbonate. Unit III (late

Campanian to early Maastrichtian) spans from 100.9 to 130.5 mbsf and consists of light gray

nannofossil ooze and chalk with 86 to 93 % carbonate. Sedimentation rates were 1.3 m/m.y. for

the late Cenomanian, 2.7 m/m.y. for the Turonian, 7.4 m/m.y. for the Campanian-Maastrichtian

and 6.6 m/m.y. for the Paleocene-Eocene.

Bermuda Rise

Bermuda Rise extends the Blake Nose transect to abyssal depths and represents the deeper

portions of the Late Cretaceous western subtropical North Atlantic (Figures 2-4 and 2-5). Site

386 (DSDP Leg 43) is located at a modem water depth of 4792 mbsl on the central Bermuda









Rise, south-southeast of Bermuda and has estimated paleodepths was below 2000-3000 mbsl in

the Albian-Maastrichian (Tuckolke and Vogt, 1979). Samples were collected from 633-819 mbsf

spanning lithologic section Units V to VI and Albian to Maastrichtian ages. Unit VI (lower

Albian to upper Cenomanian) is composed of dark greenish gray and black claystone with

radiolarian sand beds with 90 % carbonate. Unit V (upper Cenomanian to upper Maastrichtian)

contains multicolored claystones of dominantly reddish hue and subsidiary calcareous beds with

less than 10 % carbonate. The abundance of black and green clays increases down section and

Corg-concentrations exceed 10% in the vicinity of the Cenomanian to Turonian boundary. OAE 2

is defined by a 1%o increase in 613C in this Unit (MacLeod, unpublished data) (Tuckolke et al.,

1979). Sedimentation rates are 16 m/m.y. for the Albian-Cenomanian and 2.5 m/m.y. for the

Turonian-Paleocene (Tucholke et al., 1979).

Cape Verde

Site 367 (DSDP Leg 41) is located at the base of the continental rise at 4748 meters in the

Cape Verde Basin (Figures 2-4, 2-5and 2-11). It represents an abyssal site in tropical latitudes

with a paleodepth of -3700 mbsl (Kuypers et al., 2002). It is located on the eastern side of the

Mid-Atlantic Ridge, but was proximal to the Late Cretaceous tropical Atlantic gateway and to

organic-rich sequences on the African margin that are similar to the black shales on Demerara

Rise (Erbacher et al., 2004). Samples were collected from 617-695 mbsf spanning from

lithologic section Units III to IVa. The samples represent an age range of -70-101 Ma. Subunit

IVa (Albian to early Turonian) is composed of black, carbonaceous shale with organic carbon

contents from 8 to 28%. The shale becomes more calcareous, finely laminated, and burrowed

with depth. The onset of OAE 2 is defined by -6%o shift in 613C and TOC values of 20-40%

(Foster et al., 2007 and unpublished data from MacLeod). The sedimentation rate across this unit









is 20 m/m.y. Unit III (Turonian to early Eocene) is composed of multicolored silty clay layers

separated by sharp boundaries. Sedimentation rates are 12 m/m.y. for the Turonian and 6-7

m/m.y. for the Paleocene-Eocene (Lancelot et al., 1978).










Ma AGE "8Sr/Sr d13C ca
0.7072 0.7073 0.7074 0.7075 1 2 3 4


-26 -25 -24 -23
13Corg


SEA LEVEL
Eustatic Cycles &
Sequence Boundaries
Fal Rise


Figure 2-1. Summary of major geochemical, tectonic and sea level associated with mid-
Cretaceous oceanic anoxic events (OAEs) (from Leckie et al., 2002)




























Figure 2-2. Plate reconstruction: 80 Ma (Campanian, Late Cretaceous) (Lawver et al., 2002).













-3 -2 -1 0


it
tir*Aa
0 -1


1 2


-2 -3 -4


66 -
6B-
70D
72
74
76
70 -
80


84-
S92


gB

92 -E







104-
106-
108

110
112-
114.


o -



















S30 l 3
o oI 1


E- Matsbidhtoia
cooling/9taciation?





Decerara Riae
Black shales



OAE 3?


UIlniatin
OAE 2



OAE id







OAE lb


-3 -2 -1 0 1 2 3 8 12 16 20 24 28 32
paleotemperature [GC]
Central/North Atlantic 0 subtropical South Atlantic ) southern high latitudes Indian Ocean Pacific Ocean


Figure 2-3. Compilation of global benthic foraminiferal 613C and 5180 record based on data from the Late Cretaceous (from Friedrich
et al., 2007).


ilLl
L C








A W









-50" 0 5BO" 120"


180' -120' -B5' a' Bo' 120'
0 Ma Reconstruction


Figure 2-4. Present-day locations of ODP and DSDP study sites (http://www-odp.tamu.edu).


-90*
60 f"


-60" -30'


Figure 2-5. Paleogeographic map indicating the estimated location of the study sites in a plate
tectonic reconstruction generated for the CTBI (map from Kuypers et al., 2002).
represents shallow ODP Sites, a represents intermediate ODP Sites and A
represents deep ODP Sites.



























57'W 56 55 54 53 52


Figure 2-6. Location of ODP Leg 207 sites on Demerara Rise with modern bathymetry
(Modified from Erbacher et al., 2004).


Age Sites
1258 1260 1261

Maastrichlian


Campanian


Santoiran


Cornacon


Turonian


Cenomanian


Albian -

Legend
Black sales
--- Claystone
Siltstonesand stone
--- Foraminifera-nanno chalk


Figure 2-7. Schematic illustration of the stratigraphic range of the Late Cretaceous sedimentary
succession and major breaks in sedimentation of Sites 1258, 1260 and 1261 (from
Hardas and Mutterlose, 2006).
























30*N









25N


Figure 2-8. Location of the ODP Leg
odp.tamu.edu)


171B drilling transect on Blake Nose (from http://www-


Shortpoirft -- NE


Figure 2-9. Schematic interpretation of seismologic section for Blake Nose, Leg 171B (from
http://www-odp.tamu.edu).
























OcMai
tizamIT


Albio


~Ap~

LI~Am~n'h


Figure 2-10. Schematic geologic section across Goban Spur showing the sites drilled during Leg
80 (from http://www-odp.tamu.edu).


Figure 2-11. Location of Site 367, DSDP Leg 41 (from http://www-odp.tamu.edu)









CHAPTER 3
MATERIALS AND METHODS

Samples Preparation

Fossil Fish Teeth and Debris Preparation

Sediments obtained from the Oceanic Drilling Program (ODP) were wet sieved into three

fractions: <63 im, 63-125 [im and >125 rim. Phosphatic fossil fish teeth and debris were

handpicked from the >125 [im fraction. Blair (2006) demonstrated that Nd leached from the

oxide fraction of bulk sediment produced the same isotopic ratio as cleaned teeth, therefore the

samples were not reductively cleaned to remove the oxide coatings. Neodymium concentrations

in the teeth range from 100 to 400 ppm (Martin and Haley, 2000), thus, 100 to 200 pg of teeth

and debris were dissolved in -200 pl of aqua regia (equal parts of 16 N HNO3 + 12 N HC1),

which removed organic material. A minimum of 3 ng Nd can be analyzed on the MC-ICP-MS.

One ml of 2N HNO3 was added to each beaker of dissolved and dried fish teeth which was then

capped and left to sit overnight to ensure complete dissolution. The following day, a new beaker

was tared and 50 .il of solution from the first beaker was placed in the tared beaker. The weight

of the 50 .il of solution was recorded in order to calculate the dilution factor. Both beakers were

dried down. The first was re-dissolved in -150 pl of 1.6 N HCI in preparation for a two step

cation exchange column process to isolate Sr and REE, and then Nd. The second, smaller sample

was dissolved in 1 ml of 5% HNO3 with ~8ppb Rh + Re spike and left tightly capped overnight

on a hotplate in preparation for REE analyses.

Ferromanganese Oxide Coating Preparation

Samples that did not contain enough fossil fish teeth and debris for analyzes were instead

processed to extract Nd from Fe-Mn oxide coatings in the >63 tm fraction using a procedure

from Blair (2006) modified from Rutberg et al. (2000). First, -0.5 g of ground bulk sediment









were dissolved in 20 ml of buffered 2.7% acetic acid in a 50 ml centrifuge tube in order to

remove carbonates. The samples remained uncapped in the hood over night and then were

capped and agitated on the electric shaker until there was no more reaction. Then, the samples

were centrifuged and the initial 20 ml of acid were removed. Another 20 ml of buffered acetic

acid was then added to the samples and the process was repeated until there was no more

reaction. The samples were then rinsed three times with MQ grade de-ionized water. Ten ml of

0.02M Hydroxylamine Hydroxide (HH) in 25% glacial acetic was added to the residue to reduce

oxide coatings in the remaining bulk sample. The sediment and HH were mixed in centrifuge

tubes, shaken for 75 to 90 minutes, and then centrifuged to isolate the leachate. The supernatant

was decanted into clean 50 ml centrifuge tubes, centrifuged again, and then separated equally

into two Teflon beakers. The sediment residues were set aside for further analyses. In order to

remove any floating particles in the first cut, the solution was then transferred into small

centrifuge tubes, centrifuged for -10 minutes and the liquid was pipetted in the Teflon beaker.

To maximize the yield, 500 [il of MQ grade de-ionized water was added to the centrifuge tubes,

centrifuged for another -10 minutes and that liquid was added to the beaker as well. This process

was repeated one more time and the samples were then dried down and re-dissolved in -150 .il

of 1.6 N HCI in preparation for two sequential cation exchange columns.

One split of the bulk sediment extraction (5 ml) was used for REE analyses or major

element analyses. Beakers were weighed before the aliquots were transferred into them and then

the samples were dried down. The beakers containing the samples were then re-weighed to

calculate the sample weight, which range from -0.001 to 0. 1g. A dilution factor was then

calculated in order to determine the amount of 5% HNO3 with ~8ppb Rh + Re spike to add to

each sample. Dilution of -2000 times was applied to obtain optimum concentration for analyses









and reduce the matrix effect. The exact source of Nd extracted by the process is unclear.

Although the procedure is designed to liberate Nd from oxides, it may dissolve other phases,

such as phosphate, as well. For simplicity, this fraction will be referred to as the "Fe-Mn oxide"

fraction throughout the thesis.

Silicate Residues Preparation

To ensure that the carbonate and Fn-Mn oxide fractions were completely removed, an

additional 10 ml of HH was added to the sediment residues in the centrifuge tubes. These

samples were capped and set in the hood for 24 hours. The sample was centrifuged and the HH

was removed followed by a rinse in MQ grade de-ionized water. Next, 10 ml of 2 N HCl was

added to the residue for 24 hours, centrifuged and decanted and the residue was rinsed with MQ

grade de-ionized water. Next, 10 ml of 2N HNO3 was added to the sediment residue for 24 hours,

centrifuged and decanted, and the residue was rinsed with MQ grade de-ionized water. Finally, 5

ml of 30% hydroxide peroxide (H202) was added to the residues for another 24 hours in order to

remove the organic material which was abundant in samples during OAE 2. The residues were

then rinsed with water, dried down and weighed. About 0.4 g of residue was dissolved in 1.5 ml

of hydrofluoric acid (HF) and 3 ml of HNO3 of in a Teflon beaker. Tightly capped samples were

left on the hotplate for -24 hours. Once everything was dissolved, the samples were split in two

halves and dried down in preparation for column chemistry and REE analyses.

Columns Chemistry

A two step column process was used to isolate Sr and Nd from the fish teeth/debris and Fe-

Mn oxide fractions. Primary columns were used to separate Sr and bulk REE using Mitsubishi

cation exchange resin with HCl as the eluent. Strontium was eluted using 1.6N HC1, Ba was

eluted first using 2.5N HNO3 and finally bulk REEs were eluted using 4.5N HC1. The bulk REE

cut was dried down, re-dissolved in 200 pl of 0.18N HC1, and then loaded onto the second









column. Neodymium was separated from bulk REE in a quartz column packed with Teflon beads

with bis ethylhexyl phosphoric acid. The Nd was eluted using 0.18 N HCI and the samples were

then dried down. The procedural blank is -1.4 pg Nd. Another faster, single column technique

was employed for some of the later fish teeth/debris samples that did not required Sr analyses.

Small Teflon columns were packed with Ln spec resin and Nd was isolated in a single column

using 0.25N HCI as the eluent (Scher et al., submitted). For both types of columns, the Nd

fraction was dried down in preparation for isotopic analyses.

The silicate residues were passed through a primary cation column packed with Biorad

AG50W-X12 resin in order to remove Rb from the Sr cut. Strontium was eluted first using 3.5 N

HCI and then bulk REEs were eluted using 6 N HC1. The REE cut was then processed using

quartz REE columns and Teflon beads as described above. The Sr cut was dried down, dissolved

in 3.5 N HNO3 and loaded onto cation exchange columns packed with strontium-selective crown

ether resin (Sr spec). Strontium was eluted using 1.5 ml of 4xH20 following procedure by Pin

and Bassin (1992).

Neodymium Analysis

Nd isotopes were analyzed using a Nu Plasma Multi-Collector-Inductively Coupled

Plasma-Mass Spectrometer (MC-ICP-MS) at the University of Florida. The samples were re-

dissolved in 0.3 ml of 2% optima HNO3 then 10pl was pipetted out and placed in a sampling

beaker and diluted with 0.99 ml of 2% optima HNO3. The samples were then ready to be

scanned on the MC-ICP-MS. The ideal voltage range for the MC-ICP-MS is between 2-6 volts

for 143Nd. Hence, sample dilutions were adjusted based on this range. JNdi-1 standard was run

every 6 samples to obtain a daily average for the standard. This average was compared to the

long-term running average of the JNdi-1 standard from the TIMS (Micromass Sector 54 Thermal

Ionization Mass Spectrometer) of -0.512103 ( 0.000012, 2a) in order to determine a correction









factor for all samples run on that day. The long term error for the Nd MC-ISP-MS is determined

by comparing the corrected JNdi-1 values. The calculated 2a error varies on a daily basis, but the

long-term 2a error is -0.3 SNd units.

Strontium Analysis

Once Sr was isolated, 87Sr/86Sr isotopic values of the samples were analyzed on the MC-

ICP-MS using the time-resolved analysis method of Kamenov et al. (2007). The samples were

dissolved with 0.3 ml of 2% optima HNO3 then 10(l was pipetted out and placed in a sampling

beaker and diluted with 0.99 ml of 2% optima HNO3, then the sample was scanned. On-peak

zero were determined before each sample introduction in order to correct for isobaric

interference caused by impurities of Kr in the Ar carrier gas. The ideal voltage range for the

MC-ICP-MS is between 2-6 volts and sample dilutions were adjusted based on this range. NBS

987 was run every 6 samples to obtain a daily average for the standard, which was corrected to

the long-term running average of NBS 987 which is -0.710246 (2a = 0.000030). Sample values

analyzed on a given day were corrected by the same amount. This ratio is similar to the long-

term TIMS NBS 987 results (0.710240; 2a = 0.000023) therefore no further correction was

needed.

Rare Earth Elements Analyses of Fossil Fish Teeth and Fe-Mn Oxide Coatings

REE analyses were obtained using the Element 2 ICP-MS at UF. The analyses were

performed in medium resolution with Re and Rh used as internal standards. Quantification of the

results was done by external calibration using a set of prepared REE standards. These analyses

were done on a few samples from each site in order to calculate Sm and Nd concentrations for
147Sm/144Nd corrections and to obtain REE patterns for fish teeth and oxide samples. Measured

147Sm/144Nd ratios for fish teeth ranged from 0.116 to 0.147 while ratios for extracted Fe-Mn

oxide ranged from 0.125 to 0.156 (Table 3-1). Average 147Sm/144Nd ratios for each region were









used to calculate SNd(t), which corrects for age-dependent ingrowth of radiogenic Nd. This

correction ranged from 0.2 to 0.9 SNd units.

Ferromanganese USGS nodule standards, Nod-A and Nod-P (Flanagan and Gottfried,

1980) were analyzed for comparison with Fe-Mn oxide coating samples. The REEs obtained for

each samples were normalized to PAAS (Post-Archean Australian Shale) (Taylor and McLellen,

1985). REE measurements have an error of 5% and the blank is negligible.

Major Elements Analyses of Fe-Mn Oxide Coatings

Concentrations of Al, Ca, Fe, Mg, Ti, Mn, Si and Ti were analyzed on Fe-Mn oxide

coatings samples and on Nod-A and Nod-P using the Element 2 ICP-MS. The nodule samples

were prepared using 0.05 g of Nod-A and Nod-P with two drops of de-ionized water, 5 ml of

HNO3, 0.3 ml of HCl and 0.1 ml of HF (Axelsson et al., 2002). Ferromanganese oxide samples

were diluted with 5% HNO3 spiked with ~8ppb Rh + Re spike, equivalent to -15000 times

dilution to achieve suitable concentrations for major element measurements on the ICP-MS.

Quantification of the results was done by external calibration to a set of prepared standards

containing the elements of interest. The error for major elements analyses is 5% and the blank

is negligible.









Table 3-1. Average of 147Sm/144Nd measured at the different sites.
147Sm/144Nd
Site Fish Fe-Mn Oxide Residual
Teeth coatings fraction
367 0.130 0.138
386 0.147 0.147
549 0.134 N/A
550 N/A 0.162
551 N/A N/A
1049 N/A 0.138
1050 0.116 0.157
1052 0.127 0.138
1258 0.125 0.127
1260 0.125 0.125 0.097
1261 0.125 N/A









CHAPTER 4
RESULTS

Neodymium isotopes of fossil fish teeth/debris and Fe-Mn oxide coatings were analyzed

from three depth transects in northern to the equatorial North Atlantic Ocean basin: Blake Nose,

Demerara Rise and Goban Spur, and two deep sites, Bermuda Rise and Cape Verde. The aim of

the study was to determine the temporal and spatial SNd patterns across the North Atlantic in the

Late Cretaceous, and particularly across OAE 2. Thus, the distribution of the water masses in the

North Atlantic was constrained for upper bathyal to abyssal depths with higher sampling

resolution across OAE 2.

Neodymium Results

Demerara Rise Transect

Overall, SNd values at Demerara Rise in the Late Cretaceous are very non-radiogenic

except during the OAE 2 and MCE. Table 4-1 lists SNd(O) and SNd(t) values from each site. All

three sites record similar variations in SNd(t) during the Cretaceous. At Site 1258 SNd(t) in the oldest

part of the record ranges from -12.4 to -16.4 from 426.04 to 480.29 mcd (Figure 4-1). These

values increase rapidly at 425.84 mcd, shifting to more radiogenic values ranging from -7.4 to -

13.2 then decrease back to pre-shift values of -16 from 422.14 to 309.87 mcd. Starting at

308.29 mcd SNd values increase to -11.4 and remain close to this value until 67.28 mcd. In the

oldest part of the record at Site 1260 (Figure 4-2) SNd(t) values range from -12.0 to -16.1 from

502.62 to 426.66 mcd with typical values of -14 within this interval. From 453.52 to 444.57

mcd, there are two peaks in SNd(t) which range up to -11.1. A more distinct peak occurs between

426.41 to 424.81 mcd when SNd(t)values rapidly shift to more radiogenic values ranging from -9.5

to -12.9. After 424.81 mcd SNd(t) decrease to values of -13.8 to -17.8. At Site 1261 (Figure 4-3)









SNd(t) values range from -13.8 to -15.6 from 647.7 to 637.68 mcd, and then increase to -8.5 to -

13.8 from 637.0 to 629.76 mcd, before returning to -13.1 to -16.6 from 629.29 to 546.29 mcd.

Figures 4-4, 4-5 and 4-6 illustrate SNd(t) values versus time for all three sites at three

different scales. Neodymium values before and after OAE 2 are --14 to -16 at all three sites

(Figure 4-4). At Site 1260, the higher peak (-11.1) of the two peaks preceding OAE 2 correlates

with the MCE at -96 Ma from 449.07 to 446.79 mcd as defined by 613C (Figure 4-7). The more

dramatic Nd isotopic excursion of 8 ENd units recorded at all the sites from 94.08 to 93.53 Ma

coincides with OAE 2 (Figures 4-7 and 4-8), as defined by 613C (Erbacher et al., 2005). A hiatus

occurs in all three sites from -79 to 88 Ma, although the duration varies slightly between sites

(Figure 4-4). In the late Masstrichtian, SNd(t) values at Site 1258 increase to --13 and then reach -

11 in the Paleocene.

For all three sites, SNd(t) values increase very rapidly at the beginning at -94.08 to 94.03 Ma

(Figure 4-6). Figure 4-8 highlights the correlation between SNd(t) and 613C during OAE 2

Demerara Rise sites. Maximum peak SNd(t) values during OAE 2 are -7.4 at Site 1258, -9.5 at Site

1260 and -8.5 at Site 1261 (Figures 4-6 and 4-8). Neodymium isotopic values have an early peak

at the onset of the event of-7.4 at Site 1258, -9.6 at Site 1260, and -11.0 at Site 1261, then drop

to lower values ranging from -12.2 to -13.8, followed by a second, more extended Nd peak with

SNd values of -7.4 for Site 1258, -9.4 for Site 1260, and -8.5 for Site 1261 (Figures 4-6 and 4-8).

In comparison, 613C values remain on more of a plateau throughout OAE 2 with each site

recording slightly different variability. The recovery phase at the end of the event is a more

continuous decline.

Extractions of Nd from dispersed Fe-Mn oxide coatings above, within and below the

excursion at Site 1258 yield isotopic ratios that are consistent with data from fish teeth apatite









(Blair, 2006) (Table 4-2 and Figure 4-9). In addition, REE patterns from the Fe-Mn oxides

before, during and after the OAE 2 and for two USGS Fe-Mn standards (Flanagan and Gottfried,

1980) all reveal slight middle REE enrichments when normalized to PAAS (Figure 4-10). This

pattern is typical for the Fe-Mn oxide fraction (Bayon et al., 2002; Haley et al., 2004; Gutjahr et

al., 2007).

Blake Nose Transect

Table 4-3 lists the SNd(O) and SNd(t) values from fish teeth and/or Fe-Mn oxide coatings from

Sites 1049, 1050 and 1052 on Blake Nose. At Site 1049 the oldest part of the record from 157 to

128 mcd has radiogenic SNd(t) values ranging from -4.8 to -6.6. The youngest part of the record

has values ranging from -7.6 to -9.6 between 131.2 and 58 mcd, with a hiatus of >10 m.y.

separating the two sections. At Site 1050 the general pattern is similar to Site 1049 with more

radiogenic values of-4.4 to -5.9 in the older part of the record (605 to 495 mcd) and a shift

towards less radiogenic values of-7.4 to -9.0 across a hiatus in the younger part of the record

(491 to 177 mcd). Site 1052 also follows the general trend of Sites 1049 and 1050. The older part

of the record displays SNd(t) values of-3.2 to -5.2 from 677 to 478 mcd and these values decrease

to less radiogenic values of -7.4 to -9.1 from 466 to 40 mcd a hiatus.

Figure 4-14 illustrates that unlike Demerara Rise sites, SNd(t) values at Blake Nose sites

have distinct values at different depths for the older part of the section (late Aptian to Turonian).

The shallowest site, Site 1052, has the most radiogenic SNd(t) values, which range from -3.2 to -

5.2. The intermediate site, Site 1050, has intermediate SNd(t) values ranging from -4.4 to -5.9.

Although the deepest site, Site 1049, does not fully overlap with the ages of the other sites, it

records the least radiogenic values ranging from -4.8 to -6.6. Values from Site 1052 decrease

toward values from 1050 in the late Cenomanian. Site 1050 is the only site that recovered any

part of OAE 2. As defined by 613C, a short segment representing an incomplete and condensed









OAE 2 spans from 500.96 to 500.75 mbsf in core C (Figure 4-15) (Huber et al., 1999). The Nd

peak occurs at 500.77 mbsf after the 613C peak at 500.88 mbsf At the onset of OAE 2 SNd(t) is -

5.3, then it peaks to -4.4, indicating a shift of 1 SNd unit in the earliest part of the event.

Much of the Turonian-Campanian is missing at all Blake Nose sites due to a hiatus of -12

m.y. There is a shift to less radiogenic values after the hiatus and a diminished gradient between

the sites (Figure 4-14). Site 1049 has SNd(t) values that range from -7.6 to -8.7 from -72 to 56 Ma

and then decrease to -9.6 for one point at -50 Ma. At Site 1050, SNd(t) values range from -7.4 to -

9.0 from -78 to 50 Ma. Nd values at Site 1052 look similar to those at Site 1050 with SNd(t)

values that range from -7.2 to -8.2 in the Maastrichtian and late Campanian and from -8.0 to -9.2

in the Paleocene and Eocene.

Neodymium isotopic values of fish teeth/debris samples and those of extracted Fe-Mn

oxide are within error for eight out often paired samples. In general, SNd(t) values of fish

teeth/debris are slightly higher than SNd(t) values of Fe-Mn oxide samples.

Goban Spur Transect

Neodymium isotopes were sampled at lower resolution for ODP Sites 549, 550 and 551 at

Goban Spur for the Late Cretaceous in order to get a general idea of SNd(t) values at a depth

transect from a high latitude North Atlantic location (Table 4-4). Due to poor biostratigraphy and

magnetostatigraphy, no age model has been developed for these sites, thus they cannot be

correlated on a single graph. However, samples have been divided into general ages based on

low resolution biostratigraphy (Shipboard Scientific party, 1985). Fossil fish teeth and debris

were rare at Sites 549 and 550, thus mostly Fe-Mn oxide coatings were analyzed. In contrast,

fossil fish teeth and debris were abundant in the black shales common at Site 551.

Albian SNd(t) values are -8.3 and -8.5 in the late Albian (503.1 to 483.6 mbsf) at Site 549

(Figure 4-16) and then vary within a broader range from -7.6 to -10.5 from the Cenomanian to









Santonian (455.57 to 408.05 mbsf). ANd peak of-7.5 at 436.55 mbsf in the black shales may

correspond to the OAE 2 (Shipboard Scientific party, 1985). Unfortunately, there is no 613C data

for this location to verify the presence of the event. In the late Campanian and early

Maastrichtian, SNd(t) decreases to less radiogenic values ranging from -9.7 to -10.6 (404.55 to

390.55 mbsf), then increases again, ranging from -7.3 to -9.5 from late Maastrichtian to

Paleocene (380.25 to 324.05 mbsf). A single data point of -9.75 at 247.05 mbsf in the Eocene

indicates a decreasing trend.

At Site 550, SNd(t) displays a general decreasing trend from -7.1 to -10.1 at depths of 680.26

to 475.45 mbsf corresponding to the Albian to Maastrichtian (Figure 4-17). One data point at 357

mbsf suggests an increasing trend up to -7 in the Paleocene.

At Site 551, SNd(t) values decline from -7.7 to -9.6 in the Cenomanian from 142.05 to

138.62 mbsf (Figure 4-18). Following an interval of no recovery, SNd(t) values jump to -6.8 at

135.12 mbsf just before OAE 2 as defined by the 613C shift in bulk carbonates (Gustafsson et al.

2003), indicating that only the end of OAE 2 was recovered (Figure 4-19). The highest SNd(t)

reported for Site 551, -5.0 at 134.44 mbsf, occurs during the section defined as OAE 2 from

135.63 to 134.56 mbsf. Due to the lack of recovery, it is impossible to determine by how much

SNd(t) increases during OAE 2; however, following the peak, SNd(t) values return to --6.5 for the

rest of the Turonian (134.12 to 133.72 mbsf). Neodymium isotopic values then decrease

dramatically to -9.9 at 124.3 mbsf before increasing again to -8.3 at 107.58 mbsf in the

Campanian and Maastrichtian (Figure 4-18). The values for this interval are comparable to

Campanian-Maastrichtian values from the two other sites.

Neodymium isotopic values of fish teeth/debris samples and those of extracted Fe-Mn

oxide are within error for eight out often paired samples at Site 551. In general, SNd(t) values of









fish teeth/debris are slightly higher than SNd(t) values of Fe-Mn oxide samples. Five pairs of fish

teeth/debris and Fe-Mn oxide samples at Sites 549 and 550 have been analyzed. Two out of five

are falling within error and three out of five fish teeth samples plot higher than Fe-Mn oxide

samples. For one of the sample that did not fall within error, eNd(O) values of the paired samples

agreed within error. The offset may be related to the fact that Sm and Nd concentrations were

only measured for few samples and thus the correction applied to obtain the ENd(t) may be off

Bermuda Rise

Fossil fish teeth and Fe-Mn oxide coatings have been analyzed at ODP Site 386 on the

Bermuda Rise. Again, the age model for this site is poorly developed, although 613C data

(MacLeod, unpublished data) has been used to locate the position of OAE 2. Table 4-5 lists the

SNd(O) and SNd(t) values from fish teeth and/or Fe-Mn oxide coatings for Site 386. From the late

Albian to early Cenomanian eNd increases from -7.7 to -6.9 (818.54 to 804.77 mbsf) and then

remains at --6.5 from 804.77 to 740.88 mbsf until the onset of OAE 2 (Figure 4-20). OAE 2 is

identified by a 1%o 613C shift in bulk carbonate (MacLeod and Jimenez Berrocoso, unpublished

data) (Figure 4-21), which is similar to the 613C shift at Blake Nose and also indicates that the

section is incomplete. An SNd(t) increase of 2 ENd units coincides with the 613C shift, such that

values during OAE 2 peak at -4.7 at 738.93 mbsf. This eNd excursion is twice the excursion

observed at Blake Nose. From the Turonian to Santonian, ENd(t) values range from -6.8 to -7.6

from 724.29 to 692.66 mbsf and then decrease from -8.4 to -10.5 between 642.64 and 633.6 mbsf

in the Campanian or Maastrichtian (Figure 4-20). Neodymium values of fish teeth/debris

samples and those of extracted Fe-Mn oxide are within error for the two out of two paired

samples analyzed.









Cape Verde

Neodymium contained in both fossil fish teeth/debris and Fe-Mn oxide coatings were

analyzed at ODP Site 367 off Cape Verde (Table 4-6 and Figure 4-22). The age model for this

site is also poorly developed, but the position of OAE 2 was located with the 613C shift in bulk

carbonate (MacLeod and Jimenez Berrocoso, unpublished data). In the late Albian to

Cenomanian, ENd(t) ranges from -8.5 to -9.8 between 647.76 to 695 mbsf (Figure 4-22). Coring

gaps extend from -685.5 to 654.0 mbsf, from 645.7 to 644.5 mbsf and from 636.6 to 625.5 mbsf,

thus only the beginning of the event was recovered. OAE 2 has been defined by -6%o shift in

613C (Forster et al., 2007; MacLeod et al., unpublished data) starting at 641.38 mbsf (Figure 4-

23). No Nd isotopic data were collected from for the early part of OAE 2. The first eNd(t) value

within OAE 2 is -8.6 at 641.49 mbsf based of fish teeth; however, on an Fe-Mn oxide sample

from the same depth had a value of -6.5. A replicate analysis of the Fe-Mn oxide sample was

attempted, but the sample size was too small. Two ENd(t) peaks of-7.7 and -7.5 at 639.21 and

637.2 mbsf respectively correspond to shifts of -1.5 eNd units (Figure 4-23). While 613C values

are still high, eNd(t) values return to --9 (-8.6 for the fish tooth and -9.0 for the oxide). In the

Campanian and Maastrichtian, ENd(t) values are quite variable, decreasing from -9.5 to -10.1

between 621.22 and 620.84 mbsf and then increasing to -8.4 from 619.68 to 617.22 mbsf.

Analyses of the youngest sample at 617.22 mbsf produced highly distinct values for fish

teeth/debris versus Fe-Mn oxides and the oxide replicate was too small for analyses. However,

the Nd concentration of the replicate was too low for it to be analyzed on the ICP-MS. A total of

9 paired sample analyses were run and 6 agreed within error.

Rare Earth Elements Plots

Individual sample analyses of REE extracted from Fe-Mn oxide coatings are plotted for

Sites 1049, 1050 and 1052 (Table 4-7 and Figures 4-24, 4-25, 4-26), while average values are









plotted for Sites 367, 386, 550, 1049, 1050, 1052, 1258 and 1260 in order to obtain a REE

pattern typical of each location (Table 4-7 and Figure 4-27). Additional measurements were

made on uncleaned fish teeth from Sites 367, 386 and 1260 (Table 4-8 and Figures 4-28, 4-29

and 4-30). All samples have been normalized to their original weight and to PAAS (Taylor and

McLellen, 1985) and thus reflect relative concentrations. Fe-Mn oxides from Sites 550, 1049,

1050, 1052 and 1260 have the highest concentrations, whereas the deeper sites, Sites 367, 386

and 1258, have lower concentrations of REE. High concentration sites have a distinctive middle

(M-) REE bulge. Except for Sites 386 and 550, all of the sites also have slight negative Ce

anomalies. In contrast, Site 550 has a slight positive Ce anomaly, as do Nod A and Nod P.

REE analyzed from fish teeth for Sites 367, 386 and 1260 have a less pronounced MREE

bulges compared to coatings samples (Table 4-8). Site 367 has the lowest concentrations with

more pronounced Ce anomalies compared to the two other sites (Figure 4-28). Site 386 has

almost an order of magnitude higher concentration than the two other sites and small or non-

existent negative Ce anomalies (Figure 4-29). Concentrations for Site 1260 are in between Sites

367 and 386 with a similar pattern to Site 386 (Figure 4-30). A few of the fish teeth samples at

Site 367 and 1260 have HREE enriched pattern, similar to typical seawater pattern.

Sequential Extraction Results

The goal of the sequential extraction on sediment from Site 1260 at Demerara Rise was to

determine Nd and Sr isotopic values and REE patterns for the various fractions of a given sample

including fossil fish teeth, Fe-Mn oxide coatings and the residual fraction (Table 4-9). The SNd(t)

values for Fe-Mn oxide coatings fall within error of the fish teeth values for 5 out of 6 samples,

and the offset is only 0.8 ENd units for the one sample outside of error (Figure 4-31). For three of

the samples, SNd(t) values for the residual fractions are less radiogenic (more continental) than the

two other fractions. For the one remaining sample, the residue value plots within error of the









other fractions, which may indicate that the sample preparation did not completely remove the

Fe-Mn oxide coatings. In an initial experiment the residue fractions were only processed in HH

for 24h and the resulting residual SNd(t) values were dominated by the seawater signal. When the

samples were re-processed with two additional steps of 2N HCI and 2N HNO3 for 24h each, the

residue values decreased significantly.

Strontium isotopes were also analyzed for the Fe-Mn oxide and residual fraction from each

sample from Site 1260 (Table 4-9). 87Sr/86Sr ratios from Fe-Mn oxide coatings are close to

seawater 87Sr/86Sr ratios (McArthur, 2001) for the same age, but tend to be slightly more

radiogenic (Figure 4-32). On the other hand, 87Sr/86Sr ratios from the residual fractions are much

more radiogenic than seawater and Fe-Mn oxide coating ratios, indicating that they record a

more continental signature.

REE were also analyzed for the Fe-Mn oxide coatings and residual fractions (Table 4-10).

The PAAS-normalized REE plots for the Fe-Mn oxide coatings fraction show distinct MREE

enrichment for 2 out of 6 samples (Figure 4-33). The other four have lower concentrations and a

more seawater pattern. The residual fractions have lower concentrations and flat PAAS-

normalized REE patterns (Figure 4-34). Several of the samples have a positive Eu anomaly.

Major Elements Ratios

Major elements ratios were measured on a number of extracted Fe-Mn oxide coating

samples in order to further check the integrity of the Fe-Mn oxide signal (Tables 4-11). REE

values of analyzed Nod-A and Nod-P are similar to published USGS values (Flanagan and

Gottfried, 1980). Major elemental ratios of Fe-Mn oxide coatings display a high variability.

Major elements are compared to those of the average continental crust and USGS Fe-Mn nodule

standards (Nod-A and Nod-P) to evaluate whether they are similar to weathered material or Fe-

Mn coatings. The ratios Al/Fe+Mn, Ti/Fe+Mn and Si/Fe+Mn of the continental average crust are









higher by at least one order of magnitude than those of the coatings and the Fe-Mn nodule

standards. Phosphate to Fe+Mn and P/Nd ratios are higher than for the Fe-Mn nodule standards.

Elemental ratios were also analyzed on fossil fish teeth (Table 4-13) and also show high

variability.










Table 4-1. Demerara Rise Nd isotopic values from Fossil Fish Teeth from ODP Sites 1258,
1260 and 1261.
Depth Depth Age' 143/144 Nd2 3 4 5
Sample (mbsf) (mcd) (Ma) Nd NO) (t) Error


Site 1258 (3192 m)
1258A 8R-3W 20-26
1258A 17R-2W 20-26
1258A 25R-3W 60-66
1258A 27R-2W 100-106
1258A 31R-2W 10-19
1258A 31R-3W 20-26
*1258A38R-1 105
*1258A 42R-1 8
*1258A 42R-1 66
1258A 42R-2W 85-86.5
*1258A 42R-3 60
*1258B 45R-1 95
*1258B 45R-1 96
*1258B 45R-3 36
*1258B 45R-3 51
*1258B 42R-5 12
*1258A 42-6 2
*1258A 42-6 32
*1258A 42-6 60
*1258A 42R-6 66
*1258A 42R-6 96
*1258A 42R-6 116
*1258A 42R-7 7
*1258A 42R-7 26
1258A 42R-7W 50-51.5
*1258A 42R-7 71
*1258A 42R-7 93
1258A 42R-7W 105-106.5
1258A 42R-7W 115-116.5
1258C 17X-1 5-6.5
1258C 17X-1 10-11.5
1258C 17X-1 40-41.5
1258C 17X-1 50-51.5
1258C 17X-1 75-76.5


65.43 67.28
150.73 117.57
229.63 252.08
247.83 297.28
285.55 308.29
287.13 309.87
375.20
414.83
415.40
392.15 417.10
418.24
419.28
419.29
420.54
420.69
421.29
421.51
421.81
422.09
422.14
422.44
422.64
422.96
423.14
398.44 423.39
423.59
423.81
398.99 423.94
399.09 424.04
399.45 424.84
399.50 424.89
399.80 425.19
399.90 425.29
400.15 425.54


50.75
54.45
57.90
64.10
66.70
66.80
74.98
92.43
92.52
92.77
92.94
93.09
93.09
93.28
93.30
93.39
93.42
93.47
93.55
93.56
93.60
93.63
93.67
93.70
93.73
93.76
93.79
93.81
93.82
93.93
93.94
93.98
93.99
94.03


0.512035
0.512032
0.512064
0.511973
0.511948
0.511800
0.511804
0.511824
0.511867
0.511847
0.511899
0.511724
0.511748
0.511864
0.511783
0.511841
0.511945
0.511846
0.511940
0.512028
0.511938
0.511921
0.511967
0.511978
0.512083
0.512175
0.512074
0.512204
0.512148
0.511967
0.511954
0.512196
0.512213
0.512076


-11.8
-11.8
-11.2
-13.0
-13.5
-16.3
-16.3
-15.9
-15.0
-15.4
-14.4
-17.8
-17.4
-15.1
-16.7
-15.5
-13.5
-15.4
-13.6
-11.9
-13.7
-14.0
-13.1
-12.9
-10.8
-9.0
-11.0
-8.5
-9.6
-13.1
-13.3
-8.6
-8.3
-11.0


-11.4
-11.4
-10.7
-12.5
-12.9
-15.8
-16.1
-15.0
-14.2
-14.6
-13.6
-17.0
-16.5
-14.3
-15.8
-14.7
-12.7
-14.6
-12.8
-11.1
-12.8
-13.2
-12.3
-12.0
-10.0
-8.2
-10.2
-7.6
-8.7
-12.2
-12.5
-7.8
-7.4
-10.1










Table 4-1. Continued
*1258C17X1-85-86.5
*1258C17X1-105-106.5
*1258C17X1-125-126.5
1258A 42R-7W 135-136.5
*1258C17X2-10-11.5
*1258C17X2-30-31.5
1258A 43R-1W 66
1258A 43R-2W 42-44
*1258C17X2-70-71.5
1258A 43R-2W 124
*1258B 47R-1 23
1258B 47R-2W 116-117.5
1258B 47R-3W 124-126
1258B 47R-4W 102.5-104
*1258B 48R-1 111
*1258B 49R-1 45
*1258B 49R-3 31
1258A 45R 2W 51-53
*1258A 45R-2 57
1258A 46R 1W 22-24
1258A 46R 1W 41-43
1258A 46R 1W 70-72
1258A 46R 1W 100-102
*1258A 46R-2 68
*1258A 46R-4 33
*1258A47R-1 12
1258B 56R-2W 23-29
*1258C 27R-2 0
Site 1260 (2549 m)
1260 A 37-4W 130-132
1260 A 38R 5W 2-4
*1260 A 39R 1W 78
1260 B 26R 7W 10-12
*1260 A 40-1W 109
*1260 40 3W 104-372
*1260 A 42-2W 77
1260 A 42-4W 2-4
1260 B 31R CCW 3-5


425.64
425.84
426.04
399.29 426.24
426.28
426.48
400.06 426.94
401.10 426.98
426.88
401.92 428.80
429.39
409.45 431.51
410.84 432.90
412.07 434.12
435.87
439.20
441.73
445.38
445.43
448.41
448.60
448.89
449.19
450.22
452.53
456.04
452.49 477.49
480.29


342.21 341.95
352.03 352.77
357.12
366.81 368.37
369.05
372.00
389.89
389.02 391.23
396.00 398.21


94.04
94.07
94.10
94.12
94.13
94.16
94.22
94.23
94.28
94.48
94.54
94.85
95.04
95.21
95.22
95.57
95.84
96.22
96.22
96.54
96.56
96.59
96.62
96.73
96.97
97.34
99.59
100.21


66.33
68.43
69.62
72.70
72.89
73.69
78.58
78.41
89.98


0.512145
0.512120
0.511841
0.511860
0.511847
0.511805
0.511791
0.511831
0.511766
0.511754
0.511917
0.511851
0.511778
0.511780
0.511764
0.511822
0.511853
0.511795
0.511822
0.511780
0.511826
0.511832
0.511816
0.511859
0.511812
0.511873
0.511959
0.511935


0.511825
0.511770
0.511788
0.511815
0.511776
0.511801
0.511783
0.511806
0.511866


-9.6
-10.1
-15.5
-15.2
-15.4
-16.2
-16.5
-15.7
-17.0
-17.2
-14.1
-15.4
-16.8
-16.7
-17.0
-15.9
-15.3
-16.4
-15.9
-16.7
-15.8
-15.7
-16.0
-15.2
-16.1
-14.9
-13.2
-13.7


-15.9
-16.9
-16.6
-16.0
-16.8
-16.3
-16.7
-16.2
-15.1


-8.8
-9.3
-14.7
-14.3
-14.6
-15.4
-15.7
-14.9
-16.2
-16.4
-13.2
-14.5
-15.9
-15.9
-16.2
-15.1
-14.5
-15.6
-15.1
-15.9
-15.0
-14.9
-15.2
-14.4
-15.3
-14.1
-12.4
-12.8


-15.3
-16.3
-15.9
-15.5
-16.1
-15.6
-16.0
-15.5
-14.2










Table 4-1. Continued
1260B 32-1W 3-5 396.14 398.35 90.00 0.511800 -16.3 -15.5 0.2
1260 B 32R 1W 24-26 396.35 398.56 90.03 0.511741 -17.5 -16.7 0.1
1260B 32-1W 97-99 397.08 399.29 90.14 0.511701 -18.3 -17.5 0.1
1260B 32-2W 32-34 397.93 400.14 90.27 0.511697 -18.4 -17.6 0.2
1260 B 32R 2W 56-58 398.17 400.38 90.31 0.511890 -14.6 -13.8 0.1
1260B 33 1W 20-33 400.00 402.21 90.53 0.511787 -16.6 -15.8 0.1
1260 B 33R 1W 92-94 400.70 402.91 90.69 0.511813 -16.1 -15.3 0.1
1260B 33 2W 94-96 403.15 405.36 91.24 0.511688 -18.5 -17.7 0.2
1260 B35R2W 120-121 418.00 422.54 92.64 0.511831 -15.7 -14.9 0.1
1260B 35-3W 41-45 418.77 423.31 92.81 0.511873 -14.9 -14.1 0.1
1260B 35-4W 52-54 420.27 424.81 93.53 0.511979 -12.9 -12.0 0.1
1260 B 35R4W 61-63 420.37 424.91 93.55 0.511939 -13.6 -12.8 0.3
1260 B 35R4W 70-72 420.47 425.01 93.59 0.511969 -13.0 -12.2 0.2
1260B 35-4W 80-82 420.57 425.11 93.64 0.512003 -12.4 -11.5 0.2
1260 B 35R4W 90-92 420.67 425.21 93.66 0.512062 -11.2 -10.4 0.1
1260 B35R4W 103-104 420.77 425.31 93.70 0.512051 -11.4 -10.6 0.1
1260 B 35R4W 118-120 420.92 425.46 93.76 0.512097 -10.5 -9.7 0.1
1260 B 35-5W 26-27 421.42 425.96 93.87 0.512109 -10.3 -9.5 0.2
1260 B 35R5W 37-38 421.57 426.11 94.01 0.511949 -13.4 -12.6 0.1
1260B 35-5W 46-47 421.67 426.21 94.03 0.511932 -13.8 -12.9 0.1
1260B 35-5W 55-57 421.77 426.31 94.05 0.512100 -10.5 -9.6 0.1
1260 B 35-5W 60-62 421.87 426.41 94.08 0.512018 -12.1 -11.2 0.2
1260B 35-5W 90-92 422.12 426.66 94.13 0.511807 -16.2 -15.4 0.1
1260B35-5-120-121 422.41 426.95 94.47 0.511792 -16.5 -15.7 0.2
1260B 35R6W20-22 422.97 427.51 94.51 0.511880 -14.8 -13.9 0.1
1260A48R4W 10-22 438.15 441.74 95.54 0.511892 -14.5 -13.7 0.2
1260A48-6W 30-31 440.98 444.57 95.74 0.511867 -15.0 -14.2 0.1
1260A49-1W 130-131 444.40 447.99 95.99 0.511965 -13.1 -12.3 0.1
1260 A 49-2W 40-41 444.93 448.52 96.03 0.512024 -12.0 -11.1 0.2
1260A49-3W 10-12 446.05 449.64 96.11 0.511888 -14.6 -13.8 0.1
1260 A 49-3W 80-82 446.75 450.34 96.16 0.511937 -13.7 -12.8 0.1
1260A 49 4W 50-52 448.11 451.70 96.26 0.511937 -13.7 -12.8 0.2
1260A 49-5W 5-7 449.00 452.59 96.32 0.511977 -12.9 -12.0 0.1
1260A 49-5W 98-100 449.93 453.52 96.39 0.511881 -14.8 -13.9 0.1
1260 A 51R4W 10-11 466.60 470.25 97.60 0.511920 -14.0 -13.1 0.1
1260 A 52-4W 130-132 483.00 485.68 98.71 0.511947 -13.5 -12.6 0.2
1260 B 44R 1W 45-4 492.36 495.04 99.38 0.511764 -17.0 -16.1 0.1
1260 B 45R 3W 42-45 499.94 502.62 99.93 0.511780 -16.7 -15.8 0.1










Table 4-1. Continued
Site 1261 (1899 m)
1261A 39 1W 40-42 545.01 546.29 70.07 0.511799 -16.4 -15.7 0.1
1261 A 39RCCW 23-25 553.84 555.12 71.20 0.511755 -17.2 -16.6 0.1
1261 A 40R3W 10-12 557.31 558.59 72.19 0.511713 -18.0 -17.4 0.1
1261 A 41-2W 50-52 565.81 567.09 73.29 0.511796 -16.4 -15.8 0.1
1261 A 43 1W 100-102 584.01 585.29 88.24 0.511799 -16.4 -15.6 0.2
1261 A 43 3W 133-134 587.33 588.61 88.65 0.511763 -17.1 -16.3 0.2
1261 A 43 5W 42-44 591.83 593.11 89.20 0.511777 -16.8 -16.0 0.2
1261 A 44 1W 8-10 592.69 594.10 89.32 0.511826 -15.8 -15.0 0.2
1261 A 44 3W 117-119 596.78 598.19 89.83 0.511767 -17.0 -16.2 0.2
1261 A 44 5W 117-134 599.85 601.26 90.21 0.511756 -17.2 -16.4 0.1
1261 A 47-2W 90-92 623.69 621.59 93.26 0.511872 -14.9 -14.1 0.2
1261 A 47R4W 92-94 628.33 626.23 93.28 0.511823 -15.9 -15.1 0.2
1261 A 47R6W 81-83 629.72 627.62 93.45 0.511837 -15.6 -14.8 0.1
1261 A 47R6W 131-133 630.22 628.12 93.46 0.511820 -16.0 -15.1 0.1
1261 A 48R1W 20-22 631.20 628.26 93.47 0.511907 -14.3 -13.4 0.1
1261 A 48R1W 70-72 631.71 628.77 93.51 0.511858 -15.2 -14.4 0.1
1261 A 48 1W 122-124 632.23 629.29 93.54 0.511924 -13.9 -13.1 0.1
1261 A 48R2W 20-22 632.70 629.76 93.57 0.511933 -13.7 -12.9 0.2
1261 A 48R2W 70-72 633.21 630.27 93.60 0.511954 -13.3 -12.5 0.2
1261 A 48R2W 142-144 633.92 630.98 93.65 0.511978 -12.9 -12.0 0.1
1261A 48 3W 43-45 634.45 631.51 93.68 0.511931 -13.8 -13.0 0.1
1261 A 48R3W 80-82 634.81 631.87 93.70 0.511938 -13.6 -12.8 0.1
1261 A 48R3W 141-143 635.41 632.47 93.74 0.511939 -13.6 -12.8 0.1
1261 A 48R4W 141-143 636.91 633.97 93.83 0.512159 -9.3 -8.5 0.1
1261 A 48R5W 42-44 637.43 634.49 93.87 0.512076 -11.0 -10.1 0.1
1261A 48 5W 81-83 637.83 634.89 93.89 0.511898 -14.4 -13.6 0.1
1261 A48R6W 6-8 638.57 635.63 93.94 0.511896 -14.5 -13.6 0.1
1261 A 48R6W 36-38 638.87 635.93 93.96 0.511889 -14.6 -13.8 0.1
1261 B 13-2W 11-13 637.20 635.96 93.96 0.512005 -12.3 -11.5 0.2
1261 B 13-2W 67-69 637.75 636.51 93.99 0.511909 -14.2 -13.4 0.1
1261 B 13R2W 97-99 638.08 636.84 94.01 0.511948 -13.5 -12.6 0.1
1261 B 13-2W 116-118 638.27 637.03 94.03 0.512031 -11.8 -11.0 0.1
1261 B 13 3W 31-33 638.92 637.68 94.12 0.511800 -16.3 -15.5 0.1
1261 A 49R 1W 127-128 641.88 638.55 94.80 0.511797 -16.4 -15.6 0.2
1261 A 49-4W 120-122 646.27 642.84 95.21 0.511795 -16.4 -15.6 0.3
1261 A 50R2W 130-132 651.48 647.69 95.93 0.511886 -14.7 -13.8 0.2
1. Ages for Sites 1258, 1260 and 1261 were calculated after Erbacher, 2004 and 2005.
2. 143/144Nd values are normalized to the JNdi-1 average on the day the samples were analyzed and then normalized
to JNdi-1 = 0.512103 (TIMS average)
3. FNd(o)= [( Nd. INd)sample/(143Nd "NdiHuR-1] x 104










4. Nd(t)= [(143Nd/144Nd)sample(t)/(143Nd 'NdHU(t)l] x 104 using 14 Sm/144Nd = 0.125
5. Listed errors indicate the within run uncertainty. For all plots, a minimum error of 0.3 SNd unit is applied
representing the 2o uncertainty of repeat analyses of JNdi-1.
* indicates samples from Blair (2006).
Blue highlighting represents OAE 2 and purple highlighting represents MCE.


100 150 200 250 300 350 400 450
Depth (mcd)
Figure 4-1. ENd(t) values from fossil fish teeth/debris plotted versus meter composite depth (mcd)
across the Late Cretaceous from ODP Sites 1258 at Demerara Rise.












-8 2549 mbsl



-40



-12












late Paleocene- Campanian Coniacaan-Cenomanian Albian

340 360 380 40 420 440 4M0 480 500


Depth (mcd)
Figure 4-2. ENd(t) values from fossil fish teeth/debris plotted versus meter composite
across the Late Cretaceous from ODP Sites 1260 at Demerara Rise.


depth (mcd)


Depth (mcd)
Figure 4-3. ENd(t) values from fossil fish teeth/debris versus depth (mcd) across the Late
Cretaceous from ODP Sites 1261 at Demerara Rise.


Site 1260


Site 1261
- 1899 mbsl




















- late Paleo.-Camp. Coniacian Tumnian-lale Cenomanian
I I I I I


















-10 -




42




144




-16




-18 Eocene Paleocene Maastricn. Campanian San.-Con Taro Cenoman Alb
I I I I I I I I I I I A

50 60 70 80 90 100

Age (Ma)

Figure 4-4. SNd(t) values versus age across the Early Paleogene and Late Cretaceous from ODP
Sites 1258 (3192 m), 1260 (2549 m) and 1261 (1899 m) at Demerara Rise. The blue
box represents OAE 2 and the purple box represents the MCE. Ages were estimated
for the black shale interval using sedimentation rates of -1 cm/k.y. for Site 1258,
-0.25 cm/k.y. for Site 1260 and -1.5 cm/k.y. for Site 1261 (Erbacher et al., 2005)
with the initiation of the event at 94.09 Ma (Sageman et al., 2006). Below and above
the event, ages were estimated based on interpolation/extrapolation along
biostratigraphic "best fit" lines (Erbacher et al., 2004).

















-10








-14




-16 9al o -




18 early Coniacian uronian Cenomanian late Albian

88 90 92 94 96 98 100

Age (Ma)

Figure 4-5. SNd(t) values versus age across OAE 2 and MCE from ODP Sites 1258 (3192 m),
1260 (2549 m) and 1261 (1899 m) at Demerara Rise. The blue box represents OAE 2
and the purple box represents the MCE. Ages were estimated for the black shale
interval using sedimentation rates of -1 cm/k.y. for Site 1258, -0.25 cm/k.y. for Site
1260 and -1.5 cm/k.y. for Site 1261 (Erbacher et al., 2005) with the initiation of the
event at 94.09 Ma (Sageman et al., 2006). Below and above the event, ages were
estimated based on interpolation/extrapolation along biostratigraphic "best fit" lines
(Erbacher et al., 2004).



























-14




-16




18 early Turonian late Cenomanian

92.5 93 93.5 94 94.5
Age (Ma)

Figure 4-6. SNd(t) values versus age across OAE 2 from ODP Sites 1258 (3192 m), 1260 (2549
m) and 1261 (1899 m) at Demerara Rise. Ages were estimated for the black shale
interval using sedimentation rates of -1 cm/k.y. for Site 1258, -0.25 cm/k.y. for Site
1260 and -1.5 cm/k.y. for Site 1261 (Erbacher et al., 2005) with the initiation of the
event at 94.09 Ma (Sageman et al., 2006).











-36
420 r


C13
-34 -32 -30 -28 -26 -24 -22


-18 -16 -14 -12 -10 -8 -6 -4

Nld(t)

Figure 4-7. SNd(t) and 613C values versus depth (mcd) across OAE 2 (blue box) and MCE (purple
box) from ODP Site 1260. represents 613C data from Erbacher et al. (2005) and
represents unpublished 613C data from MacLeod and Jimenez Berrocoso.










13C
-34 -32 -30 -28 -28 -24 -22 -20


72 eas 0


4MD






*-S --1 --4 -12 --1 4 4 4
-t1 -16 -14 -12 -10 4 4 -4
Nd(t)


Figure 4-8. High resolution SNd(t) and 613C values versus composite depth across OAE 2 from ODP Sites 1258, 1260 and 1261. *
represents 613C data from Erbacher et al. (2005). Point A represents the onset of OAE 2 based on 613C and point D
represents the last maximum of the carbon excursion (Erbacher et al., 2005). There are 400 kyr between points A and D
(Sageman et al., 2006).










Table 4-2. Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site
1258 at Demerara Rise.
Depth Age' Fish Teeth (Blair, 2006) Fe-Mn Oxide Coatings
Sample (mcd) (Ma) 143/144Nd2 ENd(0)3 ENd(t)4 Error5 143/144Nd2 ENd(0)3 ENd(t)4 Error5

Site 1258A
42R-1, 8 414.83 92.62 0.511824 -15.9 -15.0 0.2 0.511854 -15.3 -14.8 0.2
42-6,32 421.81 93.28 0.511834 -15.7 -14.8 0.1 0.511878 -14.8 -14.4 0.2
42R-7, 7 422.96 93.40 0.511967 -13.1 -12.2 0.1 0.511963 -13.2 -12.7 0.1
42R-7, 92 423.81 93.48 0.512074 -11.0 -10.2 0.2 0.512061 -11.3 -10.8 0.1
46R-2, 68 450.22 95.60 0.511833 -15.7 -14.8 0.2 0.511845 -15.5 -15.0 0.2
1. Ages for Site 1258 are from Erbacher, 2004, 2006.
2. 143/144Nd values are normalized to the JNdi-1 average on the day the samples were analyzed and then normalized
to JNdi-1 = 0.512103 (TIMS average)
3. Nd(o)= [( Nd ,Nd)sample/( 43Nd "Nd iUR-1] x 104
4. SNd(t) = [(143Nd/44Nd)sample(t)/(143Nd 'Nd :HUR(t)-l] x 104 using 147Sm/144Nd = 0.125 for fish teeth and 0.129 for
oxides
5. Listed errors indicate the within run uncertainty. For all plots, a minimum error of 0.3 SNd unit is applied
representing the 2a uncertainty of repeat analyses of JNdi-1.
Blue highlighting represents OAE 2.


Site 1258
3192 mbsl








^ ** *


*- Fe-Mr o'xi-e coalir:s


-16
93 93 04 94 95 95 96 96

Age (Ma)

Figure 4-9. Plot of sNd(t) values versus age before, during and after OAE 2 from ODP Site 1258
at Demerara Rise. The blue box represents OAE 2. Ages were estimated for the black
shale interval using sedimentation rates of -1 cm/k.y. for Site 1258 (Erbacher et al.,
2005) with the initiation of the event at 94.09 Ma (Sageman et al., 2006). Below and
above the event, ages were estimated based on interpolation/extrapolation along
biostratigraphic "best fit" lines (Erbacher et al., 2004).


. . . . M M 5 K M F .










I I I I I I I I I I I I I I

-0- Post-OAE 2 --- Pre-OAE 2
S P -- OAE 2










II -


La Ce Pr Nd Sm Eu Gd Th Dy Ho Er Tm Yb Lu

Figure 4-10. Fe-Mn oxide coating REE patterns from ODP Site 1258 at Demerara Rise. Samples
are normalized to their initial weight and PAAS (Taylor and McLellen, 1985). Nod-A
and Nod-P represent USGS Fe-Mn oxide coatings standards. Values are display in
table 4-7.


I


I,
II










Table 4-3. Blake Nose Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Sites 1049, 1050 and 1052.
Depth Depth Age' Fish Teeth Fe-Mn Oxide Coatings
Sample (mbsf) (mcd) (Ma) 143/144Nd2 ENd(0)3 ENd(t)4 error5 143/144Nd2 ENd(0)3 ENd(t)4 error5


Site 1049 (2682m)
1049A 10-2W 45-51
1049A 13 1W 25-31
1049A 15 1W 13-19
1049A 16 2W 50-56
1049A 16 4W 62-68
1049A 17 2W 100-106
1049A 18 1W 35-41
1049A 18 1W 35-41
1049A 18 3W 100-106
1049A 18 5W 70-76
S 1049A 19 1W 24-30
1049A 20 1W 30-36
1049A 20 2W 124-130
1049A 20 5W 24-30
1049A 20 6W 40-46
1049C 13x 2W 20-22
1049A 21 2W 50-56
1049C 13x 3W 20-22
1049C 13x CC 39-40
1049A 22 1W 20-26
Site 1050 (2311m)
1050A 19x 2W 20-26
1050A 21x 3W 60-66
1050A 23x 5W 10-16


71.38
95.98
105.46
117.03
120.13
127.13
134.68
134.68
135.33
141.03
144.17
153.83
155.78
159.73
161.43
150.61
165.13
152.11
153.63
172.93


174.13
193.23
214.93


58.36
82.96
92.44
104.01
107.11
114.11
121.66
121.66
122.31
128.01
131.15
138.68
140.63
144.58
146.28
148.58
148.81
150.08
151.60
156.61


177.55
196.94
217.90


49.67
56.04
61.68
63.71
64.25
65.48
66.81
66.81
66.92
72.38
104.9
110.15
111.21
112.68
112.92
113.26
113.44
113.47
113.62
114.54


51.19
52.48
53.94


0.512129








0.512187


0.512157






0.512327
0.512339


0.512304
0.512308


-9.9 -9.5 0.2 0.512125
0.512186
0.512170
0.512162
0.512196
0.512222
0.512192
-8.8 -8.2 0.1
0.512203
-9.4 -8.7 0.1 0.512179
0.512282
0.512276
0.512264
0.512313
-6.1 -5.1 0.2 0.512314
-5.8 -4.8 0.1


-10.0
-8.8
-9.1
-9.3
-8.6
-8.1
-8.7


-8.5
-9.0
-6.9
-7.1
-7.3
-6.3
-6.3


-9.6
-8.4
-8.7
-8.8
-8.1
-7.6
-8.2


-8.0
-8.4
-6.2
-6.2
-6.5
-5.5
-5.5


0.512282 -6.9 -6.1


-6.5 -5.5 0.1
-6.4 -5.4 0.1


0.512276 -7.1 -6.2 0.1


0.512184
0.512177
0.512237


-8.9
-9.0
-7.8


-8.5
-8.6
-7.4










Table 4-3. Continued
1050A 27x 4W 20-26
1050A 30x 6W 10-16
1050C 2R 3W 10-16
1050A 35x 5W 120-126
1050C 9 2W 102-108
1050C 13 2W 22-28
1050C 15 2W 10-16
1050C 17 3W 9-15
1050C 18 2W 59-65
1050C 18 2W 130-132
*1050C 20 1W 30-36
1050C 20-4W 29-32
1050C 20 4W 120-121
1050C 20 5W 40-42
1050C 21 1W 20-21
1050C 21-1W 42-43
1050C 21 1W 47-48
1050C 21 1W 56.5-57.5
1050C 21 1W 68-69
1050C 21 1W 72-73
1050C 21 1W 105-108
1050C 21-1W 120-121
1050C 21 7W 45-46
1050C 22 1W 46-50
1050C 23 4W 60-64
1050C 23 6W 126-129
1050C 24-2W 69-72


246.43
274.13
330.23
312.13
397.05
425.04
444.23
464.92
473.52
474.21
490.93
495.40
495.60
497.02
500.40
500.62
500.67
500.77
500.88
500.92
501.26
501.45
508.75
510.28
524.52
528.17
531.30


250.58
278.28
330.23
316.28
397.05
425.04
444.23
464.92
473.52
474.21
490.93
495.40
495.60
497.02
500.40
500.62
500.67
500.77
500.88
500.92
501.26
501.45
508.75
510.28
524.52
528.17
531.30


56.06
57.93
58.76
60.49
64.17
66.63
68.34
70.15
71.11
71.19
76.99
91.74
91.81
92.31
93.31
93.39
93.40
93.44
93.48
93.86
93.89
93.91
94.63
94.78
96.18
96.54
96.85


0.512176
0.512179
0.512308
0.512320
0.512317
0.512332
0.512330
0.512332
0.512370
0.512337
0.512325
0.512332
0.512340
0.512311
0.512308
0.512295
0.512359
0.512351


-9.0
-9.0
-6.4
-6.2
-6.3
-6.0
-6.0
-6.0
-5.2
-5.9
-6.1
-6.0
-5.8
-6.4
-6.4
-6.7
-5.4
-5.6


0.512215
0.512187
0.512164
0.512192
0.512176
0.512177
0.512180
0.512167
0.512153


0.512173


-8.4
-8.3
-5.6
-5.4
-5.4
-5.1
-5.2
-5.1
-4.4
-5.0
-5.3
-5.1
-5.0
-5.5
-5.6
-5.8
-4.6
-4.7


-8.2
-8.8
-9.3
-8.7
-9.0
-9.0
-8.9
-9.2
-9.5


-7.9
-8.4
-8.9
-8.3
-8.6
-8.6
-8.5
-8.7
-9.0


-9.1 -8.6 0.1










Table 4-3. Continued
1050C 25 1W 82-85
1050C 25-3W 60-64
1050C 26 1W 53-56
1050C 26 4W 140-142
1050C 27 1W 73-76
*1050C 27 2W 100-106
1050C 277W 20-22
1050C 28 1W 70-73
1050C 28 4W 102-108
1050C 28 4W 146-150
*1050C 29 2W 100-106
1050C 29 2W 132-135
1050C 29 5W 72-75
1050C 31 1W 132-134
1050C 31 2W 100-106
*1050C 31 2W 100-106
1050C 31-6W 78-83
Site 1052 (1356m)
1052B 5 3W 98-104
1052B 11 5W 20-26
1052E 1 1W 50-56
1052E 6 1W 30-32
1052E 16 4W 12-18
1052E 19 1W 50-56
1052E 21 3W 45-46
1052E 24 2W 20-26
1052E 28 1W 100-106


539.53
542.32
548.94
554.31
558.74
560.53
567.21
568.31
573.16
573.58
579.73
580.03
583.93
597.73
598.93
598.93
604.70


37.53
87.73
140.53
185.11
285.53
301.63
332.35
359.63
397.33


539.53
542.32
548.94
554.31
558.74
560.53
567.21
568.31
573.16
573.58
579.73
580.03
583.93
597.73
598.93
598.93
604.70


40.86
92.91
140.53
185.11
285.53
301.63
332.35
359.63
397.33


97.66
97.94
98.59
99.12
99.68
99.77
100.11
100.16
100.40
100.43
100.74
100.75
100.95
101.64
101.70
101.70
101.99


36.36
37.36
41.40
45.97
63.36
64.32
67.59
68.19
69.03


0.512354
0.512344
0.512308
0.512337
0.512365
0.512349
0.512290
0.512355


0.512351
0.512334
0.512297
0.512339
0.512359
0.512298
0.512337
0.512367


0.512211


0.512156




0.512238


-5.5
-5.7
-6.4
-5.9
-5.3
-5.6
-6.8
-5.5


-5.6
-5.9
-6.7
-5.8
-5.4
-6.6
-5.9
-5.3


-4.7
-4.9
-5.6
-5.0
-4.4
-4.7
-5.9
-4.6


-4.7
-5.0
-5.7
-4.9
-4.5
-5.7
-5.0
-4.4


0.512324


-6.1 -5.5 0.1


0.512300 -6.6 -5.9 0.1


0.512303


-8.3 -8.0 0.1 0.512194
0.512172
-9.4 -9.0 0.1 0.512154
0.512172
0.512204
0.512233
-7.8 -7.2 0.1
0.512225
0.512223


-6.5 -5.9 0.1


-8.7
-9.1
-9.4
-9.1
-8.5
-7.9


-8.4
-8.8
-9.1
-8.6
-8.0
-7.4


-8.1 -7.6 0.1
-8.1 -7.6 0.1










Table 4-3. Continued
1052E 35 2W 100-106
1052E 36 4W 111-114
1052E 36 5W 19-25
1052E 38 1W 20-26
1052E 38 1W 65-66
1052E 40 1W 71-74
1052E 41 1W 10-16
1052E 41 1W 40-41
1052E 41 2W 50-52
1052E 42 2W 109-112
1052E 44 5W 68-69.5
1052E 44 CC 10-12
1052E 46 1W 20-26
1052E 46 6W 3-4.5
00
1052E 481W 91-94
1052E 49 1W 120-122
1052E 52 2W 20-26
1052E 57 5W 50-56
1052 E 58 CC


466.13
478.82
479.42
492.63
493.05
511.32
520.43
520.70
522.31
532.50
555.79
558.21
568.53
575.84
588.52
598.51
623.43
672.13
676.88


466.13
478.82
479.42
492.63
493.05
511.32
520.43
520.70
522.31
532.50
555.79
558.21
568.53
575.84
588.52
598.51
623.43
672.13
676.88


70.91
94.82
94.94
98.37
98.40
99.63
99.91
99.92
99.97
100.39
101.24
101.37
101.28
101.51
101.91
102.23
103.02
104.56
104.71


0.512189 -8.8 -8.2 0.1


0.512377
0.512358
0.512398
0.512376
0.512377


0.512403
0.512399
0.512376
0.512404
0.512421


0.512409
0.512430
0.512414



0.512402


-5.1
-5.0
-4.7
-5.1
-5.1


-4.6
-4.7
-5.1
-4.6
-4.2


-4.5
-4.1
-4.4


-4.2
-4.6
-3.8
-4.2
-4.2


-3.7
-3.8
-4.2
-3.7
-3.3


-3.6
-3.1
-3.5


0.512337
0.512377


-5.9 -5.2 0.1
-5.1 -4.4 0.1


0.512379 -5.1 -4.3 0.1


0.512377 -5.1 -4.3 0.1


0.512404
0 512380


-4.6 -3.7 0.2


-4.6 -3.8 0.1
-50 -43 00


. Ages for Sites 1049, 1050 and 1052 are from Huber et al., 1999, Petrizzio et al., 2008 and Shipboard Scientific Party, 1997.
2. 143/144Nd values are normalized to the JNdi-1 average on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (TIMS average)
3. FNNd(o)= [( d, Nd)sample/(143Nd "Nd i-HuR-1] x 104
4. SNd(t) = [(143Nd/144Nd)sample(t)/(143Nd I' 'Nd ,iHUR(t)-l] x 104 using 147Sm/144Nd = 0.125 for fish teeth at all Sites; 0.138 for coatings at Sites 1049 and 1052 and
0.157 for coatings at Site 1050.
5. Listed errors indicate the within run uncertainty. For all plots, a minimum error of 0.3 SNd unit is applied representing the 2a uncertainty of repeat analyses of
JNdi-1.
* indicates samples from Blair (2006).
Blue highlighting represents OAE 2.





















4







-0




-10


Depth (mcd)


Figure 4-11. ODP Sites 1049 at Blake Nose: ENd(t) versus depth (mcd) across the Late
Cretaceous.


-3


-4


-8

4
-6


z
cc -7


-as






-10


200 250 30 350 4G0 4o50 500 50 so
Depth (mcd)


Figure 4-12. ODP Sites 1050 at Blake Nose: ENd(t) versus depth (mcd) across the Late
Cretaceous.


Site 1049
2682 mbel

















oxides


-5 -


S-6 -


-7











80 160 240 320 400 480 560 640
Depth (mcd)


Figure 4-13. ODP Sites 1052 at Blake Nose: SNd(t) versus depth (mcd) across the Late
Cretaceous.






































80













-4



-5 "Site 1050 (2311 m)


-6 rr


.7z Site 1049 (2682 m)



-8




.9

Error
-10 -
Eocene Paleocene Maastr-Carnp S-Cono Turo-Ceno Albian-Aptian
I ..I I I ..I I .Il . 11 .

40 50 60 70 80 90 100 110

Age (Ma)

-- Site1050 Fish Teeth -- Site1052 Fish Teeth
S-0-- Site1050 Oxides -->- Site1052 Oxides
-0- Site1050 Fish Teeth (Blair, 2006)

Figure 4-14. SNd(t) values versus age (Ma) across the Late Cretaceous and early Cenozoic from
ODP Sites 1049, 1050 and 1052 at Blake Nose. Ages were estimated based on
interpolation/extrapolation along biostratigraphic "best fit" lines from Huber et al.
(2002) and Petrizzo et al. (2008) for the Albian and Cenomanian at Sites 1050 and
1052. For Site 1049 in the Aptian-Albian and all three sites for the younger part of the
record, ages were estimated based on interpolation/extrapolation along
biostratigraphic "best fit" lines from Norris et al. (1998), Huber et al. (1999) and
Huber et al. (2002).










I"C


1 1.5 2 2.5 3 3.5 4


500.2





500.4










500.8


501.0





501.2


-9 -8 -7 -6 -5 -4


Nd(t)
Figure 4-15. SNd(t) and 613C of benthic foraminifera (Huber et al., 1999) values versus depth
across OAE 2 from ODP Sitel050 at Blake Nose. The blue box represents OAE 2 and
dash lines represent hiatus in the section at 500.96, 500.93, 550.89, 500.83 and
500.76 mbsf (Huber et al., 1999).










Table 4-4. Goban Spur Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Sites 549, 550 and 551.

Depth 1 Fish Teeth Fe-Mn Oxide Coatings
Sample (mbsf) Age 143/144Nd2 ENd(0)3 ENd(t)4 Error5 143/144Nd2 ENd(0)3 ENd(t)4 Error5


Site 549 (2515m)
549 7R 2W 49-60
549 15R 2W 68-70
549 19R 2W 50-60
549 21R 1W 50-56
549 21R 1W 70-80
549 22R 2W 50-60
549 22R 5W 65-75
549 23R 2W 30-40
549 23R 5W 50-60
00 549 24R 1W 55-65
549 24R 3W 50-60
549 25R 1W 50-60
549 25R 2W 50-60
549 26R 1W 40-48
549 27R 1W 10-18
549 27R 1W 43-50
549 28R 1W 10-18
549 28R 1W 70-80
549 28R 2W 75-85
549 28R 3W 10-12
549 29R 1W 2-12
549 32R 1W 10-20
549 34R 1W 50-60


247.05
324.05
362.05
379.55
379.75
390.55
395.05
399.85
404.55
408.05
411.05
417.55
419.05
426.94
436.14
436.55
445.64
446.25
447.80
448.65
455.57
483.61
503.05


mid Eocene
early Eocene
late Paleocene
late Maastrichtian
late Maastrichtian
early Maastrichtian
early Maastrichtian
late Campanian
late Campanian
Santonian
Santonian
San.-Coniacian
San.-Coniacian
San.-Coniacian
Turonian
OAE2 ?
Cenomanian
Cenomanian
Cenomanian
Cenomanian
Cenomanian
mid Albian
mid Albian


0.512263 -7.3 -6.8


0.512198 -8.6 -7.9


0.512138
0.512252
0.512198
0.512207
0.1 0.512153
0.512096
0.512139
0.512117
0.512094
0.512188
0.512165
0.512228
0.512190
0.512178
0.1 0.512205
0.512254
0.512212
0.512171
0.512147
0.512176
0.512150
0.512212
0.512203


-9.8
-7.5
-8.6
-8.4
-9.5
-10.6
-9.7
-10.2
-10.6
-8.8
-9.2
-8.0
-8.7
-9.0
-8.5
-7.5
-8.3
-9.1
-9.6
-9.0
-9.5
-8.3
-8.5


-9.6
-7.3
-8.3
-8.1
-9.2
-10.3
-9.4
-9.8
-10.3
-8.4
-8.9
-7.6
-8.4
-8.6
-8.0
-7.1
-7.9
-8.7
-9.2
-8.6
-9.1
-7.9
-8.1










Table 4-4. Continued
Site 550 (4420m)
550 29-1W 100-104
550B 3-1W 45-49
550 47-1W 60-64
550B 8 2W 50-56
550B 10 1W 100-106
550B 11 1W 50-56
550B 15 2W 20-26
550B 17-2W 17-21
550B 17 2W 20-26
550B 21-3W 20-24
550B 22-4W 23-27
550B 24 1W 20-26
00 550B 25-1W 26-30
550B 25-IW 26-30


Site 551 (3887m)
551 2-3W 53-63
551 4-1W 125-135
551 5-1W 10-18
551 5-1W 117-126
551 5-2W7-17
551 5-2W 40-48
551 5-2W 75-81
551 5-2W 100-105
551 6-1W 8-15
551 6-1W 110-118
551 6-2W 50-60
551 6-3W 50-60


357.00
475.45
522.60
524.52
542.49
551.44
590.73
609.67
609.67
647.20
657.73
671.23
680.26


107.58
124.30
132.64
133.72
134.12
134.44
134.77
135.02
138.62
139.64
140.55
142.05


Paleocene
Paleocene
Paleocene
late Maastrichtian
late Maastrichtian
early Maastrichtian
Coniacian
Turo.-Cenomanian
Cenomanian
Cenomanian
Cenomanian
late Albian
late Albian


early Maastrichtian
late Campanian
early Turonian
early Turonian
OAE 2
OAE 2
OAE 2
OAE 2
late Cenomanian
late Cenomanian
late Cenomanian
late Cenomanian


0.512259 -7.4 -7.0


0.512191 -8.7 -8.2


0.512235 -7.9 -7.1


0.512222 -8.1 -7.3


0.512186
0.512096
0.512300
0.512291
0.512259
0.512343
0.512278
0.512290
0.512147
0.512189
0.512187
0.512241


-8.8
-10.6
-6.6
-6.8
-7.4
-5.8
-7.0
-6.8
-9.6
-8.8
-8.8
-7.7


0.1 0.512232
0.512107
0.1 0.512140
0.512113
0.512161
0.512119
0.512225
0.512175
0.512190
0.1
0.512209
0.1 0.512226
0.512230


-8.3
-9.9
-5.9
-6.0
-6.7
-5.0
-6.3
-6.1
-8.8
-8.0
-8.0
-7.0


-7.9
-10.4
-9.7
-10.2
-9.3
-10.1
-8.1
-9.0
-8.7


-7.7
-10.1
-9.4
-9.9
-9.0
-9.8
-7.7
-8.6
-8.3











'. Ages for Site 549, 550 and 551 are from Shipboard Scientific Party, 1985.
2 143/144Nd values are normalized to the JNdi-1 average on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (TIMS average)
3. 8Nd(o)= [( Nd ,Nd)sample/(143Nd '"Ndli-uR-1] x 104
4. 8Nd(t) = [(143Nd/144Nd)sample(t)/(143 Nd 'Nd,,IHUR(t)-l] x 104 using 147Sm/144Nd = 0.134 for fish teeth and 0.162 for coatings the three sites.
5. Listed errors indicate the within run uncertainty. For all plots, a minimum error of 0.3 SNd unit is applied representing the 2o uncertainty of repeat analyses of
JNdi-1.
Blue highlighting represents OAE 2.














00oo
(-A












Site 549
2515 mbsl


Eocene Paleocene
I I ,


Maas.-Camp. S-Conr Turo.-Ceno. Alblan
, I l I I, ,I ,


Depth (mbsf)
Figure 4-16. ODP Site 549 at Goban Spur: sNd(t) values versus depth across the Late
Cretaceous.


I I =i"


- Site 550
4420 mbsl


TT


I.
I

i


T 1


Maastrichlian-Campanian


Paleocene
* I .I


Turo.-Ceno. 1 Albian


360 400 440 480 520 560 600 640 680

Depth (mbsf)
Figure 4-17. ODP Site 550 at Goban Spur: sNd(t) values versus depth across the Late
Cretaceous.


. . . .











- Site 551
3887 mbsl


I


Maastrichtian-Campanian


* Turonian


Cenornanian


105 110 115 120 125 130 135 140 145

Depth (mbsf)

Figure 4-18. ODP Site 551 at Goban Spur: sNd(t) values versus depth across the Late
Cretaceous.The blue box represents OAE 2. All the samples analyzed were fossil fish
teeth and debris. No core was recovered for the interval from 135.67 to 138.67 mbsf









2 2.5 3 3.5 4 4.5 5


132 -



I : --**' .---,
134 -


136

a. o No recovery
S 138 -,
-r*

140


Nd(t)
142 --- 13 -


-11 -10 -9 -8 -7 -6 -5

Nd(t)
Figure 4-19. SNd(t) and 613C (bulk sediment, Gustafsson et al., 2003) values versus depth across
OAE from ODP Site 551 at Goban Spur. The blue box represents OAE 2. No core
was recovered for the interval from 135.67 to 138.67 mbsf.










Table 4-5. Bermuda Rise Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site 386.
Depth Fish Teeth Fe-Mn Oxide Coatings
Sample (mbsf) Age (Ma) 143/144Nd2 Nd(0)3 Nd(t)4 Error5 143/144Nd Nd(2 )3 Nd(t)4 Error5


Site 386 (2515m)
386 35R2W 9-11
386 35R2W 91-94
386 36R 1W 113-115
386 38R 3W 75-77
386 41R 1W 48-50
386 41R 2W 72-75
386 41R 3W 45-49
386 41R 5W 78-80
386 43R 2W 82-84
00 386 43R 2W 97-99
386 43R 2W 112-114
386 43R 2W 122-124
386 43R 2W 146-148
386 43R 3W 115-117
386 43R 4W 7-9
386 45R 4W 70-73
386 49R 2W 146-148
386 49R3W 41-43
386 50R 1W 71-73
386 50R 5W 123-125


633.60
634.42
642.64
692.66
717.99
719.73
720.97
724.29
738.73
738.83
738.93
739.03
739.27
740.46
740.88
770.02
804.77
806.22
813.01
818.54


Camp.-Maastr.
Camp.-Maastr.
Camp.-Maastr.
Turo.-Maastr.
Turo.-Maastr.
Turo.-Maastr.
Turo.-Maastr.
Turo.-Maastr.
Turonian
OAE 2
OAE 2
OAE 2
Cenomanian
Cenomanian
Cenomanian
Cenomanian
Ceno.-Albian
Ceno.-Albian
Ceno.-Albian
Ceno.-Albian


0.512079
0.512104
0.512209


-10.9
-10.4
-8.4


-10.5
-10.0
-8.0


0.512366 -5.3 -4.7


0.512269
0.512281
0.512281
0.512261
0.512254
0.512229
0.512222
0.512214


-7.2
-7.0
-7.0
-7.4
-7.5
-8.0
-8.1
-8.3


-6.6
-6.4
-6.4
-6.8
-6.9
-7.4
-7.5
-7.7


0.512224
0.512266
0.512247
0.512242
0.512235
0.512286
0.512296


0.512315
0.512278
0.512313


-8.1
-7.3
-7.6
-7.7
-7.9
-6.9
-6.7


-6.3
-7.0
-6.3


-7.6
-6.8
-7.1
-7.2
-7.3
-6.3
-6.1


-5.7
-6.4
-5.8


. Ages for Site 386 are from Shipboard Scientific Party, 1975.
2 143/144Nd values are normalized to the JNdi-1 average on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (TIMS average)
3. NNd(o) [( Ndl Nd)sample/(143Nd "NdliHuR-1] x 104
4. eNd(t) = [(143Nd/144Nd)sample(t)/(143 Nd 'NdIHUR(t)-1] x 104 using 147Sm/144Nd = 0.147 for fish teeth and 0.148 for coatings.










5. Listed errors indicate the within run uncertainty. For all plots, a minimum error of 0.3 SNd unit is applied representing the 2o uncertainty of repeat analyses of
JNdi-1.
Blue highlighting represents OAE 2.












Site 386
4792 mbsl

6--- Oxides



-6






-9







Maastr -Campanian Santonian Turonian Cenomanian Ceno-lateAlbian
II I I

600 650 700 750 800 850

Depth (mbsf)

Figure 4-20. ENd(t) values across the Late Cretaceous from ODP Site 386 at Bermuda Rise. The
blue box represents OAE 2. The dash lines indicate that the core did not recover for
this interval.


I 1 '. 1 'I '


i,,il,,,










13C


-28
738 r-


738.5




739


E

a.73.5
0


740




740.5




741


-27 -26 -25 -24 -23


-8 -7 -6 -5 -4 -3 -2


Nd(t)

Fs: -sh teeth c e (t) Oxides


Figure 4-21. SNd(t) and 613Corg (MacLeod and Jimenez Berrocoso, unpublished data) values
across the OAE 2 from ODP Site 386 at Bermuda Rise. The blue box represents
OAE 2.









Table 4-6. Cape Verde Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site 367.
Depth Fish Teeth Fe-Mn Oxide Coatings
Sample (mbsf) Age (Ma) 143/144Nd2 Nd(O)3 Nd(t)4 Error5 143/144Nd2 Nd()3 Nd(t) Error5

Site 367 (m)
367 17R 1W 121-124 617.22 Maastr.-Campanian 0.512164 -9.1 -8.7 0.2 0.512062 -11.2 -10.7 0.3
367 17-2W -56 618.06 Maastr.-Campanian 0.512180 -8.9 -8.4 0.3
367 17-3W 66-69 619.68 Maastr.-Campanian 0.512157 -9.4 -8.8 0.4
367 17 4W 32-36 620.84 Maastr.-Campanian 0.512089 -10.7 -10.1 0.3
367 17R4W 137-139 621.88 Maastr.-Campanian 0.512119 -10.0 -9.4 0.1 0.512119 -10.1 -9.5 0.2
367 18R 1W 63-69 636.63 OAE 2 0.512158 -9.2 -8.6 0.1 0.512139 -9.7 -9.0 0.1
367 18 1W 117-124 637.20 OAE 2 0.512217 -8.2 -7.5 0.3
367 18-2W 5-7 637.56 OAE 2 0.512195 -8.6 -8.0 0.2
367 18R2W71-73 638.22 OAE 2 0.512149 -9.4 -8.8 0.1 0.512148 -9.6 -8.9 0.2
367 18R 3W 20-22 639.21 OAE 2 0.512186 -8.6 -8.0 0.2 0.512209 -8.4 -7.7 0.2
367 18R4W 23-26 640.74 OAE 2 0.512170 -9.0 -8.3 0.1 0.512158 -9.3 -8.7 0.2
367 18-4W 87-90 641.49 OAE 2 0.512155 -9.3 -8.6 0.2 0.512268 -7.2 -6.5 0.2
367 19-3W 24-27 647.76 Ceno.-Albian 0.512137 -9.6 -9.0 0.4 0.512122 -9.9 -9.4 0.4
367 20R2W 24-27 691.20 Ceno.-Albian 0.512117 -10.0 -9.4 0.1 0.512117 -10.0 -9.5 0.1
367 20 3W 125-128 693.80 Ceno.-Albian 0.512145 -9.4 -8.9 0.1
367 20R4W 47-50 694.50 Ceno.-Albian 0.512163 -9.1 -8.5 0.2 0.512118 -10.0 -9.4 0.1
367 20R4W 96-100 695.00 Ceno.-Albian 0.512093 -10.5 -9.8 0.1 0.512107 -10.2 -9.7 0.2
1. Ages for Site 367 are from Shipboard Scientific Party, 1975
2. 143/144Nd values are normalized to the JNdi-1 average on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (TIMS average)
3. Nd(o)= [(' Nd ,Nd)sample/( 4Nd Nd I l~ R-1] x 104
4. SNd(t) = [(143Nd/144Nd)sample(t)/(43Nd 'Nd I HUR(t)-l] x 104 using 147Sm/144Nd = 0.130 for fish teeth and 0.138 for coatings.
5. Listed errors indicate the within run uncertainty. For all plots, a minimum error of 0.3 SNd unit is applied representing the 2o uncertainty of repeat analyses of
JNdi-1.
Blue highlighting represents OAE 2










F Oxides
< Fish Teeth


E

. No recovery
--------------------------
= m i m m m i m m i m . .


?
Maastr Camp Turonian Cenomanian


Cenomanian late Albian


660


Depth (mbsf)

Figure 4-22. ENd(t) values versus depth across the Late Cretaceous from ODP Site 367 at Cape
Verde. The blue box represents OAE 2.


Site 367
4748 mbsl


I I I II I M .. .










613C
--C

-36 -34 -32 -30 -28 -26 -24 -22 -20





0


-10 -9 -8


.6 -5


Nd(t


0 :NdL Fsh teeth *- C r 1-, i .. F .1- data)

cNd() Oxides -0-- 'C (Forster et ai.,2007)


Figure 4-23. ENd(t) and 613C values versus depth across the OAE 2 at ODP Site 367 at Cape
Verde. The blue box represents OAE 2. Delta13C values from bulk carbonate by
MacLeod and Jimenez Berrocoso (Unpublished data) and from bulk organic matter
by Forster et al. (2007)









Table 4-7. REE values extracted from Fe-Mn oxide samples and normalized to PAAS from USGS Standards and ODP Site 367, 386,
550, 1049, 1050, 1052, 1258 and 1260.
Samples La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Fe-Mn Nodules
*Nod-A 3.16 9.13 2.53 2.94 3.75 4.55 5.58 5.58 5.23 5.35 4.21 4.94 5.00 5.58
*Nod-P 2.74 3.63 3.09 3.75 5.36 6.82 6.01 6.23 6.14 5.65 4.21 4.20 4.64 4.19
Nod-A 2.77 8.73 2.52 2.95 3.66 4.72 5.34 4.80 5.03 4.69 4.92 5.00 4.64 4.81
Nod-P 2.64 3.71 3.32 3.97 5.40 6.94 6.40 5.94 5.81 4.75 4.69 4.68 4.44 4.27
Site 1260
B 23 6W 130-132 0.11 0.09 0.08 0.09 0.09 0.11 0.12 0.13 0.15 0.15 0.17 0.18 0.18 0.18
B 26 7W 10-12 6.51 9.19 11.95 15.38 21.53 23.21 23.54 19.13 18.35 14.62 14.05 11.89 10.40 9.74
B 35 2W 120-121 0.29 0.15 0.21 0.28 0.31 0.39 0.45 0.35 0.38 0.41 0.45 0.41 0.39 0.45
B 35 4W 103-104 3.52 2.98 5.07 6.47 8.72 11.77 10.72 8.91 8.32 6.65 5.90 4.70 3.70 3.24
B 35 5W 46-47 0.05 0.02 0.02 0.03 0.03 0.04 0.04 0.04 0.05 0.06 0.08 0.10 0.13 0.16
A 48 4W 10-12 0.05 0.03 0.04 0.05 0.05 0.06 0.07 0.06 0.07 0.08 0.09 0.10 0.11 0.12
Average 1.76 2.08 2.90 3.71 5.12 5.93 5.82 4.77 4.55 3.66 3.46 2.90 2.48 2.32
Site 1258
42R-1W 8 1.19 0.59 0.98 1.23 1.24 1.53 1.86 1.51 1.51 1.59 1.55 1.40 1.02 1.27
42R-6W 32 0.11 0.07 0.09 0.11 0.12 0.15 0.15 0.14 0.12 0.13 0.13 0.15 0.13 0.19
42R-7W 7 0.62 0.48 0.78 0.95 1.23 1.59 1.56 1.50 1.34 1.35 1.22 1.41 0.93 1.33
42R-7W 92 1.39 1.15 1.95 2.48 3.42 4.74 4.50 3.95 3.90 3.58 3.39 3.11 2.53 2.58
46R-2W 68 0.03 0.02 0.03 0.03 0.03 0.20 0.05 0.10 0.05 0.09 0.07 0.14 0.05 0.19
Average 0.67 0.46 0.77 0.96 1.21 1.64 1.62 1.44 1.39 1.35 1.27 1.24 0.93 1.11
Site 1049A
16 2W 50-56 2.22 2.13 3.62 4.87 7.14 8.18 7.60 5.69 5.15 3.94 3.62 3.03 2.55 2.23
16 4W 62-68 0.90 0.78 1.55 2.12 3.12 3.76 3.35 2.58 2.32 1.82 1.68 1.42 1.21 1.08
20 1W 30-36 6.99 5.71 10.26 13.59 16.96 19.78 22.52 17.76 16.63 14.37 12.88 10.00 7.66 6.85
20 5W 24-30 4.61 3.00 6.64 8.25 9.81 11.20 11.83 9.35 8.57 7.28 6.56 5.19 4.00 3.62










Table 4-7. Continued


21 2W 50-56
Average
Site 1050
2R 3W 10-16
13R 2W 22-28
15R2W 10-16
17R 3W 9-15
18R 2W 59-65
20R 1W 30-36
22R 1W 9-15
25R 2W 80-86
27R 2W 100-106
28R 4W 102-108
o 29R 2W 100-106
31R2W 100-106
Average
Site 1052E
24 2W 20-26
28 1W 100-106
35 2W 100-106
36 5W 20-26
38 1W 20-26
41 1W 10-16
Average
Site 550
8 2W 50-56
10 1W 100-106


3.34
3.61

1.27
0.37
0.76
1.74
0.09
0.51
2.35
0.16
0.25
1.80
3.73
2.91
1.33

0.90
0.29
2.20
0.07
3.02
0.30
1.13

0.98
0.43


1.41
2.61

1.61
0.39
0.72
0.87
0.05
0.35
1.53
0.17
0.36
2.16
3.96
3.82
1.33

0.96
0.17
1.33
0.05
3.93
0.30
1.13

1.06
0.71


4.08
5.23

2.47
0.66
1.61
3.09
0.13
0.92
3.51
0.30
0.52
3.19
5.93
5.53
2.32

1.65
0.31
3.64
0.07
6.06
0.37
2.02


5.27
6.82

3.33
0.87
2.22
4.22
0.18
1.27
4.82
0.39
0.72
4.36
8.04
7.60
3.17

2.28
0.40
5.14
0.07
8.11
0.45
2.74


1.57 1.91
1.13 1.58


6.01
8.61

5.08
1.26
3.32
5.85
0.25
1.89
6.98
0.57
1.21
6.52
11.18
11.92
4.67

3.43
0.47
7.54
0.08
11.00
0.54
3.84

2.42
2.69


7.37
10.06

5.90
1.50
4.04
7.16
0.39
2.37
8.86
0.65
1.58
7.90
13.63
14.45
5.70

4.17
0.58
9.36
0.10
12.20
0.66
4.51

2.83
3.21


8.17
10.70

5.45
1.48
3.87
7.62
0.32
2.18
8.98
0.66
1.26
7.92
13.96
13.87
5.63

4.15
0.66
10.21
0.10
12.21
0.67
4.67

2.81
2.76


6.37
8.35

4.34
1.22
3.04
6.12
0.26
1.71
7.25
0.53
0.97
6.41
11.41
11.42
4.56

3.42
0.54
8.06
0.09
9.36
0.55
3.67

2.34
2.17


6.29
7.79

3.77
1.11
2.68
5.68
0.24
1.55
6.92
0.48
0.82
5.84
10.69
10.14
4.16

3.26
0.55
7.89
0.10
8.31
0.53
3.44

2.11
1.76


5.43
6.57

2.91
0.93
2.10
4.69
0.20
1.24
5.95
0.38
0.65
4.89
9.22
8.16
3.44

2.74
0.50
6.70
0.09
6.44
0.46
2.82

1.62
1.22


5.01
5.95

2.66
0.85
1.85
4.11
0.20
1.12
5.48
0.34
0.59
4.50
8.51
7.32
3.13

2.57
0.47
6.06
0.10
5.63
0.43
2.54

1.41
1.02


3.89
4.71

2.28
0.74
1.48
3.22
0.16
0.93
4.60
0.28
0.49
3.70
7.08
6.09
2.59

2.16
0.39
4.84
0.10
4.19
0.35
2.00

1.09
0.79


2.90
3.66

1.93
0.61
1.19
2.49
0.14
0.79
3.80
0.22
0.43
3.03
5.79
4.96
2.12

1.87
0.31
3.89
0.09
3.22
0.28
1.61

0.86
0.66


2.62
3.28

1.79
0.57
1.10
2.31
0.13
0.73
3.60
0.21
0.42
2.97
5.65
4.71
2.02

1.82
0.30
3.67
0.09
2.95
0.26
1.51

0.74
0.60










Table 4-7. Continued
11 1W 50-56 1.15 0.98 1.75
15 2W 20-26 1.05 1.82 2.48
17 2W 20-26 0.63 0.55 1.32
24 1W 20-26 1.16 1.10 2.03
Average 0.90 1.04 1.71
Site 386
38 3W 75-76.5 0.13 0.29 0.35
41 5W 78-80 0.04 0.07 0.10
43 2W 82-84 0.02 0.02 0.01
43 2W 146-147.5 0.03 0.02 0.03
Average 0.05 0.10 0.13
Site 367


2.12 2.63 3.11
3.35 5.99 6.52
1.87 3.01 3.60
2.85 4.43 5.82
2.28 3.53 4.18

0.51 0.90 1.07
0.13 0.21 0.27
0.01 0.02 0.03
0.04 0.05 0.14
0.17 0.29 0.38


3.13 2.56 2.38
5.84 4.83 4.21
3.14 2.31 1.94
4.88 3.67 3.12
3.76 2.98 2.59

0.91 0.75 0.65
0.21 0.17 0.15
0.02 0.01 0.01
0.06 0.05 0.05
0.30 0.24 0.21


17 1W 121-124 0.01 0.04 0.03 0.03 0.05 0.24 0.04 0.04 0.03
17 4W 32-35.5 0.02 0.04 0.04 0.04 0.06 0.28 0.05 0.04 0.03
00
18 1W 117-124 0.15 0.04 0.06 0.05 0.06 1.19 0.06 0.05 0.05
18 2W 71-73 1.14 0.61 1.24 1.69 2.33 4.10 3.42 2.90 3.15
Average 0.33 0.18 0.34 0.46 0.62 1.45 0.90 0.75 0.82
Samples normalized to initial weight and then PAAS (Taylor and McLellen, 1985).
*USGS CRM, certified reference material values (Flanagan and Gottfried, 1980).
Error is +/_ 5%


1.87 1.66 1.31
3.08 2.83 2.55
1.40 1.19 0.93
2.41 2.14 1.65
1.93 1.71 1.39

0.48 0.44 0.38
0.11 0.10 0.08
0.01 0.01 0.01
0.04 0.04 0.04
0.16 0.15 0.13

0.03 0.03 0.04
0.03 0.02 0.03
0.05 0.05 0.05
3.16 3.37 3.22
0.82 0.87 0.83


1.04 0.89
2.27 2.10
0.77 0.68
1.37 1.27
1.16 1.05

0.34 0.31
0.07 0.06
0.01 0.01
0.04 0.04
0.11 0.11

0.04 0.04
0.03 0.02
0.06 0.06
3.07 3.14
0.80 0.82

































I I I I I I I
La Ca Pr Nd Sm Eu Gd


I I I I I I IL
Tb Dy Hio Er Tm Ybt Lu


0.81


0 I








La Ce Pr Nd Smn Eu Gd Tb Dy Ho Er Tm Yb Li


-- 1049A 20 1W 30-36 cm
Nod-P -U- 1049A 20 5W 24-30 cm
--- 1049A 16 2W 50-56 cm -- 1'-. .A 21 2'AW 5C-55 T




Figure 4-24. Fe-Mn oxide coating REE patterns from ODP Site
1049 at Blake Nose. Samples are normalized to their
initial weight and PAAS (Taylor and McLellen, 1985).
Nod-A and Nod-P represent USGS Fe-Mn oxide
coatings standards.


-*-- 1050 17R 3W 9-15 0 105027R 2W 100-106
--- Nod P --1050 3R 2Li59-65
-*- 1050 2R 3W 10-16 4 1050 20R 1W 30-36 150 29R 2W -C- C6
-B-1050 22R 1W 9-15 0 1050 31R 2W 100-106
-a- 1050 15R 2W 10-16 0 1050 25R 2W 80-86


Figure 4-25. Fe-Mn oxide coating REE patterns from ODP Site
1050 at Blake Nose. Samples are normalized to their
initial weight and PAAS (Taylor and McLellen, 1985).
Nod-A and Nod-P represent USGS Fe-Mn oxide
coatings standards.


I I I I I P I I I I I I I
























p-* ~ -T
~k~3


o.01 '--' ----- '-'-- --'-- -- ---- ------ ---l



La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu


-A- 1052E 35R 2W 100-106
-- Nod P 1052E 36R 5W 20-26
1052E 24R 2W 20-26 1052E 3R 1W 20-26




Figure 4-26. Fe-Mn oxide coating REE patterns from ODP Site
1052 at Blake Nose. Samples are normalized to their
initial weight and PAAS (Taylor and McLellen, 1985).
Nod-A and Nod-P represent USGS Fe-Mn oxide
coatings standards.


0.01 .
La Ce Pr Nd Sm Eu Gd Th Dy Ho Er Tm Yb Lu


SrA Site 550 Site 1258
--Nod P O Site 1260
Site 367 -0- Site 1050
--Site 386 0 Site 1052


Figure 4-27. REE plots of the average values from Fe-Mn oxide
coatings from ODP Sites 367, 386, 550, 1049, 1050,
1052, 1258 and 1260. Samples are normalized to their
initial weight and PAAS (Taylor and McLellen, 1985).
Nod-A and Nod-P represent USGS Fe-Mn oxide
coatings standards.


I I I I I I I I I I I I I I


I I I I I I I I I I I I I I









Table 4-8. REE values of uncleaned fossil fish teeth normalized to PAAS from ODP Site 367, 386 and 1260.
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Site 1260
B 32-2W 32-34 4.16 2.89 3.81 4.23 4.50 5.06 5.52 4.74 4.78 4.62 4.88 4.67 4.17 4.27
B 35-3W 41-45 7.79 6.47 9.25 10.99 12.73 15.32 15.54 12.60 12.09 10.54 10.48 8.25 6.75 6.16
B 35-4W 52-54 12.58 6.33 10.49 11.98 13.37 16.43 19.15 16.39 17.53 16.93 17.00 14.85 12.68 12.43
B 35-5W 46-47 13.58 6.65 9.11 10.30 10.84 13.73 16.07 14.62 16.80 17.70 20.09 20.98 20.31 20.73
B 35-5W 90-92 15.24 12.49 17.83 20.31 23.17 27.10 28.85 25.19 25.32 22.76 22.05 19.26 15.54 14.48
A 49-1W 82-84 4.53 3.30 3.76 4.12 4.15 5.18 5.59 5.05 5.54 5.54 5.99 5.59 4.58 4.57
A 49-2W 40-41 5.83 2.87 4.01 4.63 5.11 6.42 7.84 7.38 8.73 9.62 10.88 11.04 9.91 10.43
Site 386
35R-2W 9 -11 36.33 46.51 52.78 59.30 75.00 90.60 87.99 84.82 78.89 71.95 68.38 69.44 55.29 62.86
35R-2W 91-94 43.42 68.01 71.63 80.88 104.45 124.50 125.26 117.86 112.82 99.79 94.63 93.52 76.98 79.18
36R-1W 113-115 47.16 90.55 90.28 104.78 144.93 170.17 168.67 157.25 146.07 117.11 101.67 87.07 64.51 61.57
43R2W 112-114 0.08 0.11 0.07 0.07 0.10 0.24 0.11 0.06 0.08 0.07 0.06 0.09 0.06 0.05
43R 2W 146-148 0.36 0.41 0.59 0.78 1.30 2.01 2.25 2.49 3.04 2.93 3.09 3.37 3.37 3.25
43R 3W 115-117 0.08 0.28 0.17 0.24 0.35 0.47 0.48 0.43 0.46 0.41 0.41 0.40 0.36 0.32
43R 4W 7-9 0.01 0.05 0.03 0.05 0.08 0.10 0.08 0.06 0.07 0.06 0.06 0.07 0.07 0.06
45R-2W 70-73 62.52 60.63 68.26 77.97 97.94 124.70 134.81 123.79 126.29 110.17 101.23 84.31 60.55 52.12
49R-2W 146-148 120.85 138.61 188.04 228.68 316.88 389.93 389.69 352.46 327.06 268.93 237.21 204.52 152.83 151.62
49R-3W 41-42 104.28 126.91 158.46 188.84 254.24 309.64 311.63 282.80 260.66 217.79 189.90 169.47 124.05 128.12
50R-IW 71-72 80.68 99.83 120.82 145.27 194.58 239.49 240.84 217.40 200.06 166.92 145.68 126.21 93.60 92.94
50R-5W 123-125 86.76 114.43 118.99 141.25 185.77 227.86 233.38 219.97 201.13 176.67 156.50 147.64 104.82 121.88









Table 4-8. Continued
Site 367
20R 4W 47-50 20.75 7.88 16.87 19.72 21.45 29.03 32.80 30.49 32.40 32.73 33.49 33.03 29.01 28.03
20R 2W 24-27 29.73 26.60 42.47 50.62 62.69 72.88 73.24 63.87 59.79 51.25 48.11 42.92 37.09 34.98
18R 4W 88-91 10.16 4.48 8.35 10.70 14.37 21.15 25.68 26.50 32.19 36.93 43.57 48.92 50.55 56.43
17R4W 137-139 6.62 6.37 6.41 7.07 8.17 9.62 11.02 10.53 11.11 10.37 10.71 10.61 9.38 9.08
17R 1W 121-124 1.29 0.46 2.27 2.71 3.17 4.05 4.09 3.82 3.96 3.73 3.81 3.78 3.27 3.19
Samples normalized to initial weight and then PAAS (Taylor and McLellen, 1985).




























1




0.1 i--- i i i I i i i i-i----- i
La Ce Pr Nd Sm Eu Gd Th Dy Ho Er Tm Yb Lu


-0- 367 17R 'W 137-139

-- 367 20R 2W 24-27 367 17R IW 121-124

--367 18R 4W 88-91



Figure 4-28. Fish teeth REE patterns from ODP Site 367 at Cape
Verde. Samples are normalized to their initial weight
and PAAS (Taylor and McLellen, 1985).


108


0.1 '
La Ce Pr Nd Sm Eu Gd Tb Dy He Er Tm Yb Lu



.-..- 386 49R-2W 146-148
386 35R-2W 91-94 -U- 386 49R-3W 41-42
*- 386 36R-1W 113-115 ',-, 50R-1W 71-72
El 386 50R-5W 123-125


Figure 4-29. Fish teeth REE patterns from ODP Site 386 at
Bermuda Rise. Samples are normalized to their initial
weight and PAAS (Taylor and McLellen, 1985).


I I I I I I I I I I I I I I


I I I I I I I I I I I I I I











1000


I I i I I I I I I I I I I L
La Cc Pr Nd Sm Eu O T1 Dy Ho Er Tm Yb Lu


A -:. L; 32-2W 32-34
--- 1260B 35-3W 41-45
-- lF;l 'R35-4W 52-54
- 1260B 35-5W ,-47


- 1260A 49-2W 40-41


Figure 4-30. Fossil fish teeth REE patterns from ODP Site 1260 at Demerara Rise. Samples are
normalized to their initial weight and PAAS (Taylor and McLellen, 1985).


- -~










Table 4-9. Nd and Sr isotopic values from fossil fish teeth and Fe-Mn oxide coatings and
residual fraction from ODP Site 1260 at Demerara Rise.
Depth Age 143/144 Nd2 3 4 5 87/86r 6
Sample (mcd) (Ma) Nd ENo) EN(t) Error Sr Error

Site 1260
Fish teeth
B 26-7W 10-12 366.81 72.70 0.511815 -16.1 -15.4 0.2
B 35-2W 120-121 418.00 92.64 0.511831 -15.7 -14.9 0.2
B 35-4W 103-104 420.77 93.70 0.512051 -11.4 -10.6 0.1
B 35-5W 46-47 421.67 94.03 0.511933 -13.8 -12.9 0.1
A 48-4W 10-12 438.15 95.54 0.511892 -14.6 -13.7 0.1
A 52-4W 130-132 483.00 98.71 0.511947 -13.5 -12.6 0.2
Fe-Mn oxide coatings
B 26-7W 10-12 366.81 72.70 0.511782 -16.7 -16.0 0.2 0.707746 0.000009
B 35-2W 120-121 418.00 92.64 0.511806 -16.2 -15.7 0.1 0.707550 0.000008
B 35-4W 103-104 420.77 93.70 0.512018 -12.1 -11.1 0.1 0.707737 0.000031
B 35-5W 46-47 421.67 94.03 0.511928 -13.9 -13.2 0.1 0.707489 0.000009
A 48-4W 10-12 438.15 95.54 0.511903 -14.3 -13.3 0.1 0.707537 0.000010
A 52-4W 130-132 483.00 98.71 0.511914 -14.1 -13.1 0.1
Residual fraction
B 26-7W 10-12 366.81 72.70 0.511633 -19.0 -18.7 0.1 0.708657 0.000006
B 35-2W 120-121 418.00 92.64 0.511836 -14.8 -14.5 0.4 0.708881 0.000009
B 35-4W 103-104 420.77 93.70 0.511765 -16.2 -15.9 0.1 0.708640 0.000015
B 35-5W 46-47 421.67 94.03 0.709219 0.000008
A48-4W 10-12 438.15 95.54 0.511805 -15.4 -15.0 0.2 0.710389 0.000015
1. Ages for Site 1260 are from Erbacher, 2004.
2 143/144Nd values are normalized to the JNdi-1 average on the day the samples were analyzed and then normalized
to JNdi-1 = 0.512103 (TIMS average)
3. F-Nd(o)= [ Nd. l Nd)sample/(143Nd "NliNd uR-1] x 104
4. FNd(t)= [(143Nd/144Nd)sample(t)/(143Nd 'NidIHUR(t)-l] x 104 using 14 Sm/144Nd = 0.125
5. Listed errors indicate the within run uncertainty. For all plots, a minimum error of 0.3 SNd unit is applied
representing the 2a uncertainty of repeat analyses of JNdi-1.
6. Measured 8 Sr/86Sr of the NBS-987 standard = 0.712025 +/- 0.000023 (2a).
Blue highlighting represents OAE 2.













Fish Teeth


-12 Reuuai fractio


-4 F


-20


TO T5 50 85 90 95 100

Age (Ma)
Figure 4-31. SNd(O) from fossil fish teeth and Fe-Mn oxide coatings and residual fraction from
ODP Site 1260 at Demerara Rise. Ages estimated after Erbacher et al. (2004 and
2005).


- ~


-- --- ---


0.7080


0.7075 -


0 .7 0 7 0 . . . .
70 75 80 85 90 25 it0

Age(Ma)

Figure 4-32. 87Sr/86Sr values from sequential extraction samples. Errors for Sr values are
smaller than symbols. Seawater values from McArthur et al. (2001). Ages estimated
after Erbacher et al. (2004 and 2005).


0.7105


0.7100


0.7095





0.7085


I g i l l i l. . . . . . .









Table 4-10. REE values of Fe-Mn oxide coatings and residual fraction normalized to PAAS from ODP Site 1260 at Demerara Rise.
Samples La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Site 1260-coatings
B 23 6W 130-132 0.110 0.091 0.085 0.085 0.094 0.114 0.122 0.130 0.151 0.147 0.166 0.181 0.183 0.179
B 26 7W 10-12 6.508 9.187 11.950 15.380 21.531 23.215 23.536 19.130 18.348 14.617 14.052 11.887 10.399 9.737
B 35 2W 120-121 0.289 0.148 0.214 0.280 0.307 0.394 0.452 0.351 0.379 0.405 0.449 0.411 0.387 0.451
B 35 4W 103-104 3.524 2.984 5.070 6.467 8.720 11.769 10.724 8.907 8.322 6.653 5.902 4.703 3.705 3.244
B 35 5W 46-47 0.050 0.018 0.023 0.027 0.028 0.039 0.044 0.040 0.050 0.062 0.081 0.099 0.126 0.164
A 48 4W 10-12 0.051 0.029 0.037 0.046 0.050 0.063 0.070 0.062 0.073 0.078 0.093 0.096 0.106 0.123
Site 1260-residual fraction
B 23 6W 130-132 0.318 0.225 0.234 0.216 0.195 0.899 0.177 0.155 0.168 0.155 0.182 0.198 0.210 0.218
B 26 7W 10-12 0.863 0.692 0.707 0.673 0.596 0.518 0.496 0.424 0.410 0.369 0.422 0.471 0.504 0.530
B 35 2W 120-121 0.145 0.099 0.111 0.109 0.104 0.152 0.101 0.091 0.097 0.097 0.114 0.125 0.136 0.153
B 35 4W 103-104 0.106 0.072 0.082 0.080 0.075 0.103 0.079 0.065 0.068 0.064 0.073 0.079 0.087 0.090
B 35 5W 46-47 0.220 0.141 0.169 0.154 0.138 0.162 0.137 0.122 0.125 0.123 0.147 0.172 0.182 0.206
A 48 4W 10-12 0.270 0.206 0.208 0.205 0.184 0.192 0.177 0.133 0.130 0.123 0.151 0.174 0.194 0.210
Samples normalized to initial weight and PAAS (Taylor and McLellen, 1985).
Error is +/- 5%.


















l5 r- l -*l "-*---. -d P



CO 1 -









0.0 1 I--I I I I I I I
La C. Pr Nd Sm Eu Gd Th Dy Ho Er Tm Yb Lu



1260B 35 2W 120-121
---V-- Nod-P
-$-1260B 23 6W 130-132 r '260B 35 5W 46-47
1260B 26 7W 10-12


Figure 4-33. Fe-Mn oxide coatings REE patterns from ODP Site
1260 at Demerara Rise. Samples are normalized to
their initial weight and PAAS (Taylor and McLellen,
1985). Nod-A and Nod-P represent USGS Fe-Mn
oxide coatings standards.


0.. ..01 '.'' ' ' '
La Ce Pr Nd Sm Eu Gd Tb Dy Heo Er Tm Yb Lu



-*- 1260B 23 6W 130-132
---- 26 7W 10-12 260D 35 5W 46-47
-- 1260B 35 2W 120-121




Figure 4-34. Silicate residues REE patterns from ODP Site 1260
at Demerara Rise. Samples are normalized to their
initial weight and PAAS (Taylor and McLellen, 1985).


S.. ._-a .. L- [A iA


I I I I I I I I I I I I I I









Table 4-11. Major elements rations of Fe-Mn oxide coatings from Sites 367, 386, 550, 1049 and 1052.
Al Mg Ti Si P Nd 1
Sample Fe/Nd Mn/Nd Fe/Mn P/Nd AENd
Fe + Mn Fe+Mn Fe+Mn Fe+Mn Fe+Mn Fe+Mn
Average Continental Crust
9.93 3.78 6.3E-01 31.68 N/A N/A 4.4E+02 87.5 5.0 N/A
Fe-Mn Nodules
Nod-A* 0.07 0.10 0.01 N/A 0.02 3E-04 1160.6 1968.1 0.6 65.0
Nod-P* 0.08 0.06 0.01 N/A 6E-3 4E-03 483.8 2427.5 0.2 16.8
Nod-A 0.07 0.09 9.9E-03 N/A 0.02 4E-04 1043.5 1766.4 0.6 55.3
Nod-P 0.07 0.05 7.4E-03 N/A 0.01 4E-04 398.1 2012.1 0.2 14.4
Site 367
a17 1W 121-124 0.05 0.03 1.2E-04 1.21 0.04 2E-05 41106.7 584.2 70.4 1730.6 2.05
17 4W 32-35.5 0.04 0.03 1.6E-04 1.03 0.15 3E-05 32980.1 84.6 389.8 5057.3
18 1W 117-124 0.01 2E-03 3.1E-04 0.14 0.01 8E-06 118502.6 0.6 200184.0 1058
18 2W 71-73 0.57 0.11 2.6E-04 0.40 2.15 3E-03 363.3 16.5 22.0 815.8 0.11
19 4W 75-78 0.02 0.01 9.0E-05 0.37 0.08 1E-05 88679.8 N/A N/A 7082.2
Site 386
38 3W 75-76.5 0.13 0.09 9.0E-05 0.78 0.52 8E-04 88.6 1103.6 0.1 617.6
41 5W 78-80 1.96 1.26 3.4E-03 0.19 12.11 9E-03 99.9 17.4 5.7 1420.3
43 2W 82-84 4E-03 2E-03 1.0E-05 0.42 0.01 3E-06 351842.3 24855.6 14.2 2483.9
43 2W 122-123.5 4E-03 2E-03 3.0E-05 0.14 2E-03 2E-06 583410.3 856.9 680.8 1263
43 2W 146-147.5 0.04 0.01 7.0E-05 0.19 0.06 5E-05 19447.8 31.2 623.6 1180.4 0.18
Site 550
8 2W 50-56 0.28 0.36 4.1E-04 0.01 1.11 5E-02 11.2 9.6 1.2 23.1
10 1W 100-106 0.61 0.19 8.8E-04 0.43 1.77 8E-03 112.8 13.9 8.1 224.3
11 1W 50-56 0.19 0.22 1.7E-04 0.01 0.89 3E-02 19.5 14.3 1.4 30.3
15 2W 20-26 0.59 0.19 1.3E-03 1.99 5.94 3E-03 345.4 3.7 94.0 2072.8
17 2W 20-26 0.16 0.03 1.1E-04 1.08 0.68 1E-03 619.8 50.3 12.3 453.8










Table 4-11. Continued
24 1W 20-26 0.31 0.08
Site 1049A
10 2W 45-51 0.55 0.7
13 1W 25-31 0.13 0.16
16 2W 50-56 0.52 0.2
16 4W 62-68 1.93 1.06
20 1W 30-36 1.33 1.23
20 5W 24-30 1.70 3.82
21 2W 50-56 1.92 9.06
Site 1052E
24R 2W 20-26 0.33 0.11
28R 1W 100-106 0.10 0.35
35R 2W 100-106 0.29 0.12
" 36R 5W 20-26 0.02 1.94
38R 1W 20-26 0.55 0.49
41R 1W 10-16 0.05 0.57
1. AeNd represents SNd teeth- SNd coatings.
indicates samples that fall within OAE 2.


1.6E-04

5.E-03
1.9E-04
2.7E-03
3.5E-03
6.6E-03
3.9E-03
2.2E-03

9.9E-04
5.6E-04
2.4E-03
3.2E-04
3.0E-03
2.3E-04


0.81

0.99
1.28
3.23
1.21
0.11
0.09
0.04

0.81
0.07
1.36
0.01
0.65
0.03


1.33

3.15
0.40
1.24
8.06
18.11
17
27.88

1.07
0.43
2.40
0.11
4.07
0.18


3E-03

3E-05
2E-06
3E-03
1E-02
4E-01
4E-01
4E-01

3E-03
5E-03
4E-03
2E-03
3E-02
1E-03


312.7

8990.4
70963.7
142.9
81.6
2.1
2.5
1.8

312.6
192.3
237.1
511.5
38.9
765.4


15.7

30744.7
521255.8
176.0
10.7
0.3
0.3
1.0

2.5
7.6
1.3
18.7
0.2
7.3


19.9 437.4


0.3
0.1
0.8
7.6
7.2
8.5
1.9

122.7
25.2
188.6
27.4
195.3
104.3


125152
238403
396.9
744.6
43.6
47.0
75.6

338.6
85.2
571.9
59.6
159.3
139.1


*USGS CRM, certified reference material values (Flanagan and Gottfried, 1980).


0.40

0.15













0.56
0.57









Table 4-12. Major elements rations of fish teeth/debris from Sites 549, 1050, 1052, 1260 and 1261.
P Nd
Sample Fe/Nd Mn/Nd P/Nd P/Fe Fe/Mn Ca/Nd
Fe+Mn Fe+Mn


549 16R-2W 68-78 983.07 0.74 6.02 1.23 797.31 132.45 4.88 1731.32
1050C 20R-4W 29-32 410.36 0.40 5.97 0.21 153.71 25.73 28.81 376.47
1050C 21R-1W 42-43 397.47 0.76 1.79 0.12 47.73 26.65 15.42 141.93
1052E 34R-4W 111-114 347.12 0.53 4.53 0.24 211.02 46.63 18.84 693.93
1052E 38R-1W 20-26 138.33 0.96 0.96 0.02 68.70 71.28 39.81 172.55
1052E 42R-2W 109-112 138.80 0.36 6.83 0.14 113.14 16.56 50.14 371.66
1260A 49-1W 82-84 24.87 0.16 1.06 0.29 1326.79 1253.99 3.63 3184.79
1260A 49-2W 40-41 16.24 0.14 2.28 0.20 1017.99 446.82 11.25 2398.36
1260A 49-3W 80-82 44.28 0.21 1.17 0.15 523.89 446.96 8.03 1244.71
1260B 52-4W 130-132 25.03 0.52 1.67 0.21 652.88 389.87 8.12 1576.69
1261B 5-4W 131-132 109.93 0.14 0.78 0.26 144.83 185.18 2.95 582.26
1261B 6-5W 5-7 69.53 1.01 2.62 0.14 383.67 146.21 18.73 965.34









CHAPTER 5
DISCUSSION

Seawater Signal

All the North Atlantic sites that recovered sediment from OAE 2 record SNd values that

increase to varying degrees in association with the changes in environmental and sedimentologic

conditions. It is important to consider whether this isotopic shift documents changes in bottom

water values as opposed to diagenetic alteration or the introduction of unique materials related to

conditions during OAE 2. Several lines of evidence support the idea that the shifts in SNd do

record changes in seawater Nd. First, specific lithologies might be more susceptible to diagenetic

alteration; however, the most dramatic SNd shift at Demerara Rise occurs within a continuous

black shale section that spans the entire Cenomanian and Turonian. In addition, there is no gNd

shift associated with the major hiatus and the dramatic lithologic boundary between

Cenomanian-Turonian black shales and overlying Late Campanian-Eocene chalks.

Second, Blair (2006) demonstrated that Fe-Mn oxide coatings extracted were effective

archives of deep sea Nd isotopes on Cenozoic to Cretaceous timescales. These extracted Fe-Mn

oxide coatings and fossil fish teeth apatite yield the same SNd values above, within and below the

OAE 2 excursion illustrating that two distinct phase yield the same isotopic values (Table 4-2

and Figure 4-9). This implies that either both phases are recording original seawater or, less

plausibly, that these two distinct phases were altered in such a way that the final products have

the same value. In addition, the coherence between phases implies that both fossil fish

teeth/debris and Fe-Mn oxide coatings are robust archives for Nd isotopes even under anoxic

conditions. This is particularly noteworthy for the Fe-Mn oxides, which are redox sensitive.

Furthermore, REE patterns and concentrations from fossil fish teeth and Fe-Mn oxide

coatings are similar pre-, syn- and post-OAE 2 (Figure 4-10), supporting the idea that measured









SNd values during OAE 2 were not influenced by: 1) input of young volcanic material, which

would have a HREE enrichment when normalize to PAAS (Rollinson, 1993) and 2) continental

materials, which would have flat REE patterns when normalized to PAAS (e.g., McLennan,

1989), as observed in the residue fractions in this study (Figure 4-34). REE patterns of all the Fe-

Mn oxide samples are similar to those of USGS Fe-Mn nodule standards, revealing slight MREE

enrichments when normalized to PAAS, which is the typical signature of REE fractionation into

oxide coatings (Elderfield, et al., 1981; Bayon et al., 2002; Haley, 2004; Gutjahr et al., 2007).

Experiments during this study illustrated that this oxide REE pattern dominates the residual

fraction unless it is carefully and thoroughly removed with strong acids. This observation

suggests that the oxides are more likely to contaminate the residue, rather than the residue

contaminating the extracted oxide fraction.

Major element data also argue that the signal extracted from Fe-Mn oxides represents

seawater rather than continental material. Major elements from Fe-Mn oxide coatings (Table 4-

11) show variability between samples that could represent variable amounts of Fe and Mn in the

coating or influence from clay and/or terrigenous material which would be reflected by higher

concentrations of Al, Ti and Si. (e.g., Dellwig et al., 2000; Wehausen and Brumsack, 2002).

However, Al to Fe+Mn, Ti to Fe+Mn and Si to Fe+Mn ratios of Fe-Mn oxide coatings are

similar to those of the USGS Fe-Mn nodule standards (Nod-A and Nod-P) and few order of

magnitude lower than those of the average continental crust (Taylor and McLennan, 1985)

suggesting a non-crustal source and that no significant detrital contamination occurred during the

leaching of the Fe-Mn oxide phase with HH. Phosphorus to Fe+Mn and P/Nd ratios are higher in

Fe-Mn oxide coatings than in Nod-A and Nod-P suggesting extraction from apatite of some P

and Nd during the leaching process. Fossil fish teeth/debris and extracted Fe-Mn oxides show









similar REE patterns, thus unique identification of these two phases is difficult. However,

inclusion of apatite in the Fe-Mn oxide fraction would not affect this study since both phases

record the same Nd isotopic values.

Demerara Rise

Very low ENd values across much of the Late Cretaceous set Demerara Rise apart from the

rest of North Atlantic sites. Despite the range of upper to mid bathyal depths sampled, all three

Demerara Rise sites (Sites 1258, 1260 and 1261) are characterized by exceptionally low ENd

values ranging from -14 to -17.5 (Figures 5-1). These values are uniquely non-radiogenic for

open ocean sites at this time when North Atlantic values range from -3 (at Site 1052, Blake

Nose) to -10 (at Site 367, Cape Verde), Central Pacific values range from -2.5 to -5.5 (Frank et

al., 2005; Blair, 2006), and Tethys values range from -6 to -11.5 (Stille et al., 1990; Soudry et al.,

2004; Puceat et al., 2005). Only two, very shallow sites display similar non-radiogenic values: an

Angolan site (--16.9, Grandjean et al., 1987) and a Swedish site (-17, Puceat et al., 2005) (Figure

5-1). It is highly unlikely that eNd values at Demerara Rise are influenced by water masses

originating at either of these sites, because none of the sites located between Sweden and

Demerara Rise record similar non-radiogenic values and the Angolan data precedes any

estimates for the deep connection between the North and South Atlantic. One possible source of

non-radiogenic Nd in the Demerara region is the neighboring the Archean Guyana Shield (Blair,

2006). In fact, sediments from the Orinoco River, which drains the Guyana Shield, yield non-

radiogenic ENd values of -19.6 to -30.7 (Goldstein et al., 1997).

Introduction of river-derived Nd into bottom waters on Demerara Rise implies that this

fresh water source had to become dense enough to sink to intermediate depths. The Cenomanian

is characterized by warm conditions that could lead to high evaporation in the tropical

epicontinental basins surrounding Demerara Rise, that could result in the sinking of warm and









saline surface water to intermediate or bottom water depths (Brass et al., 1982; Mosher et al.,

2007) in a situation similar to modem Mediterranean outflow.

Evidence for ventilation of deep waters in the tropical North Atlantic is provided by the

lack of stratification of the water column observed in the SNd values for the depth transect at

Demerara Rise. It is important to point out that the deepest site at Demerara is only at mid

bathyal depths at the CTBI; thus, this warm, saline water only needs to penetrate to intermediate

depths. The intermediate water mass formed in this process, which has been referred as to the

Demerara intermediate water (DIW) (MacLeod et al., submitted), is a predicted outcome of an

Albian-Turonian ocean GCM. The model by Poulsen et al. (2001) indicates that significant

downwelling occurred off the northeastern coast of South America in the Late Cretaceous

independent of the paleogeography or atmospheric CO2 concentrations. The fact that this water

mass defined by very low SNd values is not observed outside the Demerara region suggests that

the volume of water formed must have been relatively small; however, the continuous

observation of non-radiogenic SNd values from the Albian to the Maastrichtian in this region,

with the exception of OAE 2 and the MCE, indicates that local ventilation was a long term

process.

Ocean Anoxic Event 2

The correlation between the 6-8 SNd unit shift and the 6 %o 613C shift during OAE 2 at all

three Demerara Rise sites suggests that the changes in Nd isotopes are related to dramatic

environmental changes associated with this event. None of the other sites studied contain

complete OAE 2 sections that are well defined by 613C data. Only the beginning of the event was

recovered at Sites 367 at Cape Verde and 1050 at Blake Nose, and only the end of OAE 2 was

recovered at Site 551 at Goban Spur (Huber et al., 1999; Gustaffson et al., 2003; MacLeod,

unpublished data), while 613C data do not clearly identify an OAE 2 peak at Site 386 on









Bermuda Rise. Based on these partial records, SNd values appear to shift towards more radiogenic

values during all of the defined OAE 2 events, with peak FNd values ranging from -4.4 to -5.0 at

sites from the northern North Atlantic (Sites 386, 551 and 1050), and from -7.4 to -9.5 at tropical

North Atlantic sites (Sites 367, 1258, 1260 and 1261) (Figures 5-1, 5-2 and 5-3B).

Even though correlation between sites is difficult, the fact that a positive SNd shift is

recorded throughout the North Atlantic during OAE 2 implies that the cause of the shift is related

to at least a basin-wide process. Therefore, possible causes include a basin-wide disturbance in

oceanographic circulation and/or introduction of Nd from an external source, such as the

Caribbean Large Igneous Province (LIP) or a change in continental sources.

Implication for the Cause of OAE 2

1. Continental sources

One of the hypotheses to explain OAE 2 is a change in weathering inputs to the ocean

during this interval that would increase the nutrient flux to the ocean, enhancing surface

productivity, and thus leading to anoxia (Jenkyns et al., 1980). Neodymium isotopes argue

against either a change in the intensity of weathering on the continents or a change in the types of

rocks being weathered. First, a change in weathering would be expected to occur relatively

slowly, yet the shift in Nd is quite rapid, estimate are that the initial increase in 613C took

120,000 to 150,000 years (Sageman et al., 2006). Second, it seems unlikely that SNd values would

shift twice, once at the MCE (recorded at Site 1260) and again the OAE 2, and then return almost

as rapidly to pre-excursion values. In addition, local inputs that are believed to give DIW its

distinct isotopic signature are non-radiogenic, thus, a positive SNd excursion would require a

decrease in weathering intensity or inputs, which is difficult to reconcile with an enhanced

hydrologic cycle predicted during OAE 2 (Calvert and Pederson, 1990; Erbacher and Thurow,

1997).









Moreover, Nd and Sr data from the residual fraction, extracted Fe-Mn oxide and fossil fish

teeth/debris argue that the Nd shift observed in the latter two phases during OAE 2 is not

influenced by a change in the composition of rocks being weathered as recorded by the residual

fraction. Neodymium isotopes of the residual fraction are 1.5 to 3 PNd units less radiogenic than

fish teeth and Fe-Mn oxide coatings samples except for one sample younger than OAE 2 that

may not have been fully cleaned (Figure 4-31). Also, the SNd values of the residue illustrate little

variation before, during and after. The largest change observed in this fraction occurs in the

sample that is much younger than OAE 2. Strontium isotopes of the residue are also distinct from

Fe-Mn oxide coatings, which are similar to the Sr signal of seawater (Figure 4-32). The very

radiogenic residue 87Sr/86Sr values again indicate that the residue is recording a more continental

signal that is affected by OAE 2.

Another way to produce the FNd shift observed at Demerara Rise that could be related to

continental weathering inputs would be to shutdown DIW formation in response to increased

freshwater input to the basin associated with the enhanced hydrologic cycle. Although this

scenario provides an intriguing explanation for the shift recorded at Demerara Rise, it cannot

explain the shifts observed at other North Atlantic sites. Thus, even if this process contributed to

the magnitude of the shift of Demerara Rise, another process is required to account for the

positive shift observed basin-wide during OAE 2.

2. Caribbean large igneous province

The eruption of the Caribbean LIP has been dated within a range of 87 to 95 Ma (Alvarado

et al., 1997; Sinton et al., 1998; Hauff et al., 2000). Recently, Snow et al. (2005) calculated a

more accurate age of 93.46 + 0.38 Ma for the beginning of the eruption using 40Ar/39Ar

techniques, which correlates well with the Cenomanian-Turonian boundary. The volcanic

activity would have then continued until -87 Ma (Snow et al., 2005). Several authors have









argued that hydrothermal circulation related to this emplacement would introduce fertilizing

trace metals to surface water (Sinton and Duncan, 1997; Kerr, 1998; Snow et al., 2005), and thus

potentially releasing radiogenic Nd into the ocean. Therefore, the positive Nd shifts observed at

North Atlantic sites could reflect hydrothermal inputs, characterized by Nd value ~+10 (oceanic

basalts). Nd released by hydrothermal vents in today's ocean is removed quantitatively by oxide

formation at the ridge (e. g. Halliday et al., 1992; Sinton and Duncan, 1997). However, under

anoxic conditions, radiogenic Nd might be transported farther away. In fact, many other

elemental abundance anomalies are recorded during OAE 2 in the WIS (Orth and al., 1993,

Snow et al., 2005). These anomalies likely originate from intense seafloor spreading and

hydrothermal activity in the Pacific and Caribbean corridor as they are larger in the west and

decrease toward the east, suggesting a west to east circulation pattern that connects the

Caribbean LIP in the equatorial eastern Pacific with North Atlantic sites.

In this scenario, we would expect to see a similar Nd shift at western North Atlantic sites

(Blake Nose, Bermuda Rise and Demerara Rise) and a smaller Nd shift at eastern North Atlantic

sites (Goban Spur and Cape Verde). The observed Nd shifts recorded throughout the North

Atlantic does not appear to follow this pattern (Figure 5-2); however, this may reflect the fact

that most of the sites do not contain complete OAE 2 records. Moreover, this scenario requires

development of deep ocean anoxia prior to transmission of the Nd signal, which implies that the

613C excursion should lead the SNd excursion. Higher resolution records at the onset of the

excursion are required to thoroughly evaluate this situation, but based on current data at

Demerara Rise it appears that either the two records increase at the same time or ENd slightly

leads 613C (Figure 4-8). The shift recorded at Demerara Rise also implies that enhanced mixing

between the Demerara Rise and the rest of the North Atlantic is required in addition to input









from the LIP source. Otherwise Demerara Rise would continue to be dominated by the non-

radiogenic signal of the DIW.

The LIP hypothesis cannot be discounted for the cause of OAE 2 without additional data.

If this hypothesis is valid, Nd data from the WIS (Pueblo, Colorado) should display a strong

radiogenic Nd excursion because this region records strong trace metal signals (Orth et al., 1993;

Snow et al., 2005). In addition, Pacific sites, such as Shatsky Rise (northwest Pacific) might be

expected to record an excursion because of their proximity to the Caribbean LIPs. Moreover, it

would be interesting to evaluate whether trace metal abundance pattern vary at Demerara Rise as

they do in the WIS and whether they record the same pattern of two peaks seen with ENd.

3. Oceanic circulation

Alternatively, shifts in SNd can be interpreted in terms of changes in circulation. In this case

it is assumed that values of the end member water masses did not change in response to altered

Nd inputs to the ocean. Time slice maps before, during and after OAE 2 illustrate potential

changes in ocean circulation patterns associated with this event. Before OAE 2, gNd values in

most of the North Atlantic are similar to reported Tethyan values (Figures 5-1 and 5-3A),

suggesting dominant east to west intermediate/deep water flow. In contrast, SNd values of

northern and northeastern North Atlantic intermediate to deep sites (Blake Nose, Bermuda Rise

and Goban Spur) increase to -5 at OAE 2, while the deeper tropical sites (Demerara Rise and

Cape Verde) have values of --7.5 (Figure 5-2). This distribution is compatible with clockwise

circulation of Pacific-sourced water through the basin that mixes with some Tethyan outflow

prior to arriving in the tropical region (Fig. 5-3B). This transition could be caused by weaker

production of intermediate to deep warm, saline water derived from the Tethys Ocean, possibly

in association with the enhanced hydrologic cycle (Calvert and Pederson, 1990; Erbacher and

Thurow, 1997), or by enhanced invasion of the Pacific water mass into the North Atlantic.









The fact that all three Demerara Rise sites record similar excursions during OAE 2

indicates that the water column was well mixed for mid to upper bathyal paleodepths before,

during and after OAE 2 at this location. OAE 2 also represents the only time slice with similar

values throughout the tropical Atlantic at both Demerara Rise and Cape Verde. A decrease in

6180 values of benthic foraminifers at the base of OAE 2 indicates that bottom water salinity

decreased and/or that bottom water temperatures increased (Friedrich et al., 2006). Increased

precipitation associated with an accelerated hydrological cycle at the CTBI could have enhanced

freshwater runoff, thereby leading to a partial or even total shutdown of the DIW (Friedrich et

al., 2006, Mosher et al., 2007). As a result, North Atlantic water with a more radiogenic signal

would have replaced DIW at Demerara Rise during OAE 2.

Several authors have proposed that OAE 2 is related to the initial deep water connection

between the North and South Atlantic Ocean basins that resulted in an abrupt change in Atlantic

deep water circulation (Tucholke and Vogt, 1979; Summerhayes, 1981; Wagner and Pletsch,

1999; Poulsen et al, 2001, 2003; Pletsch et al., 2001; Kuypers et al., 2002), although the timing

of this deep connection is still controversial with estimates ranging from the late Cenomanian to

Maastrichtian (MacLeod and Huber, 1996; Frank and Arthur, 1999; Frank et al., 2005, Friedrich

and Erbacher, 2006). As several authors pointed out, the injection intermediate or deep water

from the South Atlantic into the North Atlantic following the opening of the equatorial Atlantic

gateway could create favorable conditions for vertical advection of nutrients, widespread

productivity, expansion of the minimum oxygen zone and the accumulation of organic matter

(Tucholke and Vogt, 1979; Leckie et al., 2002). This connection could also account for the

positive shift in Nd through the introduction of South Atlantic water. GCM simulations (Poulsen

et al.; 2001, 2003) for the CTBI indicate that deepening of the Equatorial Atlantic Gateway









(EAG) initiated vigorous circulation between the North and the South Atlantic, which led to

freshening at depths in the North Atlantic consistent with observations at Demerara Rise

(Friedrich et al., 2006). According to the model North Atlantic deep circulation transits from

anticyclonic (counterclockwise) to well-developed cyclonic gyre that circulates through the

North and South Atlantic basins at the opening of the gateway. Neodymium data can be

correlated to the model with Albian-late Cenomanian anticyclonic circulation, introducing water

from the Tethys (Figure 5-3A), followed by the initiation of a cyclonic gyre during OAE 2 that

redistributes Pacific-sourced waters (Figure 5-3B). These Pacific waters could be mixed with

less radiogenic Tethys or South Atlantic derived deep water masses in the tropical North Atlantic

leading to increased SNd values at Cape Verde and Demerara Rise.

There are no published SNd data for the South Atlantic in the Late Cretaceous. In fact, the

oldest South Atlantic data come from the late Paleocene when SNd values for the South Atlantic

ranged from -7 to -10 (Thomas et al., 2003). Assuming that this water was sourced from the

Southern Ocean and that this source did not change between the Late Cretaceous and Early

Cenozoic, the upper end of the South Atlantic range is identical to estimates of Tethys waters

(Puceat et al., 2005; Soudry et al., 2006). Cape Verde and Demerara Rise both record SNd values

of -7.5 at the CTBI, which could represent a mixture of Pacific water with either Tethys water or

South Atlantic water at -9.

The role of EAG in the formation of OAE 2 cannot be tested without Late Cretaceous SNd

values from the South Atlantic, such as ODP Sites 511 and 530. Even with these data, the SNd

values may be too similar to Tethys sourced waters to differentiate between source regions.









Late Cretaceous North Atlantic Circulation


Late Aptian-Cenomanian

From the Albian to Cenomanian, it appears that the western North Atlantic is fed by a main

water mass with SNd values ranging from -8 to -9 (Figures 5-1 and 5-3A). This water mass is

recorded at Goban Spur (Sites 549, 550 and 551) and Cape Verde (Site 367). The Tethys Ocean

has SNd values of --9 for shallow sites for the same interval of time (Puceat et al., 2005). GCMS

of oceanic circulation for the Late Cretaceous indicate that warm, saline intermediate to deep

water likely formed in subtropical regions of excessive evaporation in the eastern Tethys at this

interval of time, much like the Mediterranean in the modern North Atlantic (Brass et al., 1982;

Arthur et al., 1985, 1987; Barron and Peterson, 1990; Barron et al;, 1993; Bice and Marotzke,

2001; Poulsen et al., 2001, 2003). Nowadays, the Mediterranean outflow into the North Atlantic

is the warmest and densest intermediate water mass formed in the oceans (Hay et al., 1993).

Similar ENd values recorded at shallow sites in the Tethys (Puceat et al., 2005; Soudry et al.,

2006) and intermediate to lower bathyal depths in the North Atlantic also suggest that warm and

saline waters formed in the Tethys (Tethys Bottom Water, TBW) flowed westward in the North

Atlantic (Figure 5-3A). At the same time, Bermuda Rise (Site 386) has Nda values ranging from -

7.5 and -6.5, slightly more radiogenic than deep eastern North Atlantic sites but also slightly less

radiogenic than the deepest site at Blake Nose (-5 to -6.5, Site 1049) which had values similar to

the Pacific (Figure 5-1). This indicates that the western North Atlantic (Bermuda Rise and Blake

Nose) may have recorded a deep water mass that was a mixture of less radiogenic Tethys and

more radiogenic Pacific waters (Figure 5-3A). In contrast, throughout this time interval,

Demerara Rise sites maintain their unique non-radiogenic SNd values (--16), consistent with a

locally derived intermediate/deep source that dominated in the Demerara region, but did not

extend to Cape Verde to the east or Blake Nose to the north.









Unlike Demerara Rise, the late Aptian to Cenomanian FNd data at Blake Nose (Sites 1049,

1050 and 1052) suggest a stratified water column. This stratification could be due to eolian input

of volcanic ash at the surface or the presence of different water masses at different depths.

Volcanism in the Late Cretaceous was widespread in the Gulf of Mexico (Byerly, 1991). The

closest volcanic activity to Blake Nose was located in the Mississippi Embayment and thus,

volcanic material may have been introduced to this region. As a result, a gradient in SNd values

could have developed that would be comparable to the modern Pacific Ocean in which

radiogenic SNd values are recorded at the surface with decreasing values at depth due to seawater

particle exchange (Goldstein and Hemming, 2003). This model suggests relatively sluggish

circulation (Poulsen et al., 1999; Kuypers et al., 2002) and limited ventilation of intermediate

waters in the western North Atlantic from the Albian to Cenomanian. The other option would be

shallow Pacific-sourced waters to overlie a bottom water mass sourced from the Tethys. This

scenario implies more vigorous mixing within the basin. The fact that ash concentrations at Sites

1050 and 1052 do not change as SNd values change (Norris et al., 1998) argues that the

stratification is related to layers with distinct SNd values and more vigorous circulation patterns.

From -103 to 95 Ma (late Albian to early Cenomanian), SNd values at the shallow site (Site

1052) progressively decrease towards values recorded at the intermediate site (Site 1050) and

they appear to almost merge from -100.4 to 99.6 and again at -95 Ma, suggesting a reduced

vertical stratification between the two sites which represents depths of-500 and 1500 m

(Petrizzo et al., 2008). This collapse of upper-ocean stratification as been proposed as cause of

the late Albian OAE Id (-99 Ma) based on the 6180 record at Site 1052 (Wilson and Norris,

2001; Petrizzo et al., 2008).









Turonian

The return to less radiogenic gNd values after the OAE 2 event (-9 at Cape Verde; -6.5 to -

8.2 at Goban Spur; -6.8 at Bermuda Rise and -6 at Blake Nose) (Figures 5-1 and 5-3C) can be

explained by continued opening of the Equatorial Atlantic Gateway and the resulting increased

flow of South Atlantic deep water into the North Atlantic basin (Poulsen et al, 2001, 2003;

Pletsch et al., 2001; Friedrich et al., 2007) or by re-establishment of Tethys warm, saline deep

water formation. Compilation of 180 data (Figure 2-2) indicates that both North and South

Atlantic deep waters started to progressively cool in the late Turonian (Friedrich et al., 2007),

suggesting that Tethys-derived warm, saline deep water was not the major water mass in the

North Atlantic for this interval of time. Although Nd isotopes cannot distinguish between South

Atlantic and Tethyan waters, the 6180 data suggest that the decrease in SNd(t) records increase

South Atlantic water flow and thus the opening of the EAG.

Coniacian-Santonian

Goban Spur and the western Tethys (Puceat et al., 2006) record SNd values of -10.2 to -

11.2 in the Santonian that appear too low to represent South Atlantic or Tethys-derived waters

(Figures 5-1). Puceat et al. (2006) proposed that these non-radiogenic waters represented the

initiation of non-radiogenic deep water formation in the northern North Atlantic. Unfortunately,

this interval of time is represented by a hiatus at most of the study sites (Bermuda Rise, Blake

Nose, Demerara Rise and Cape Verde), which Wagner and Pletsch (1999) attributed to erosive

deep water currents due to the recent deep connection between the North and South Atlantic.

Campanian-Maastrichtian

The shift towards less radiogenic values at Blake Nose in the Campanian could indicate

restriction of the connection to the Pacific, possibly due to tectonic changes in the Caribbean

region (Pindell et al., 2006). By this time, all of the sites in the North Atlantic, with the exception









of Demerara Rise, record values of --8.5 (Figure 5-1) indicating homogenized deep water within

the North Atlantic basin. While Demerara returned yet again to production of a local water mass,

the rest of the basin records values that would be expected due to inflow of deep South Atlantic

waters, which is reasonable given that all models support a fully open Equatorial Atlantic

Gateway at this time (Frank and Arthur, 1999; Friedrich et al., 2006, 2007). Benthic foraminifera

6180 values are similar in the North and South Atlantic (Figure 2-2) (Huber et al., 2002) during

the Campanian, also supporting the idea of a fully opened EAG and deep water connection

between the two oceanic basins (Friedrich et al., 2007).

For the first time since OAE 2, Demerara Rise Nd isotopic values at the only site analyzed

for this young interval (Site 1258) increase rapidly toward more radiogenic SNd values of -11 in

the mid to late Maastrichtian, but they remain lower than those observed at other North Atlantic

sites for the same interval of time. Values at Bermuda Rise do start to approach similar ENd

values; however, the age model at Bermuda Rise is poorly constrained, therefore the age of the

decrease observed at Site 386 is not well known. This SNd shift at Demerara Rise from unique

non-radiogenic background values to more Atlantic-like values in the mid to late Maastrichtian

suggests the end of conditions necessary for formation of the DIW. The Latest Cretaceous is

associated with a global cooling trend; as a result, evaporation rates and water temperatures may

have decreased to the point that warm, saline intermediate water could not form any longer.
























CO -12


-14


-16


-18


60 70 80 90 100


Age (Ma)

-E- Site 367 (CV) M BM1969.05 (Burton et al., 1997) A Westem Europe (Puc6at et al., 2005)

-U- Site 386 (BR) -0- Pacific (Blair, 2006)

W Sweden (Puc6at et al., 2005)

-U- Site 1050 (BN) -7- Tethys (Puc&at et al., 2005)

.....V Tethys, Soudry etal., 2006)

Figure 5-1. Compilation of SNd(t) values across the Late Cretaceous in the North Atlantic, Pacific
and Tethys. Ages for Sites 367, 386 and 511 are estimated after biostratigraphic data
from Shipboard Scientific Party (1975, 1975 and 1985 respectively).






























1261 1260 1258 1050 551


386 367


Sites


SInhte, m1r.innit. sir.s GAL 2 O Intermediate sites ;re-OAE 2


A Deep sites OAE 2


A Deep sites pre-OAE 2


Figure 5-2. Pre-OAE 2 8Nd values and maximum values reached during OAE 2 at ODP Sites
367, 386, 551, 1050, 1258, 1260 and 1261.


1050 386
(-4.4) 551
( (-5.0) 0
1258 367
(-7.4) (-7.5)
1261
(4.5) 120
1260
(-9.5)
A








0 0







































A. Albian-Cenomanian (-100 Ma)


Figure 5-3A. Albian to Cenomanian paleogeographic map of the North Atlantic (Lawver et al.,
2002). M represents shallow ODP Sites, 0 represents intermediate ODP Sites and A
represents deep ODP Sites. Values represent SNd(t) with color corresponding to the
depth of the site. DIW = Demerara intermediate water; PWM = Pacific Water Mass;
TWM = Tethys Water Mass. Arrows represent intermediate and deep circulation
pathways.










60' 60"

western Interior
SSeaway,'




-. 7 -7 30"





TWM
S--7.5








-90' -60' -30' 0'

B. CTBI

Figure 5-3B. Cenomanian-Turonian Boundary Interval paleogeographic map of the North
Atlantic (from Kuypers et al., 2002). M represents shallow ODP Sites, 0 represents
intermediate ODP Sites and A represents deep ODP Sites. Values represent OAE 2
peak SNd(t) with color corresponding to the depth of the site. DIW = Demerara
intermediate water; PWM = Pacific Water Mass; SAWM = South Atlantic Water
Mass; TWM = Tethys Water Mass. Arrows represent intermediate and deep
circulation pathways. Incursion of water masses into the Western Interior Seaway
after Orth (1993), Leckie et al. (1998).










-90' -60' -30' 0"
60" i -II m 60"

western InteriorW C. r







/ ~--39



SAPWM---SothAl a We M ; t. W TW sr


i-90 -" -ep cc h-9
*A








-90* -60' -30' 0'

C.Turonian

Figure 5-3C. Turonian paleogeographic map of the North Atlantic (from Kuypers et al., 2002).
N represents shallow ODP Sites, O represents intermediate ODP Sites and A
represents deep ODP Sites. Values represent SNd(t) with color corresponding to the
depth of the site. DIW = Demerara intermediate water; PWM = Pacific Water Mass;
SAWM = South Atlantic Water Mass; TWM = Tethys Water Mass. Arrows represent
intermediate and deep circulation pathways.






































D. Campanian-Maastrichtian boundary

Figure 5-3D. Campanian-Maastrichtian paleogeographic map of the North Atlantic (Lawver et
al., 2002). M represents shallow ODP Sites, represents intermediate ODP Sites and
A represents deep ODP Sites. Values represent SNd(t) with color corresponding to the
depth of the site. DIW = Demerara intermediate water; SAWM = South Atlantic
Water Mass and PWM = Pacific Water Mass. Arrows represent intermediate and
deep circulation pathways.









CHAPTER 6
CONCLUSIONS

Neodymium isotopic values were analyzed on fossil fish teeth/debris and extracted Fe-Mn

oxide coatings from depth transects at Blake Nose, Demerara Rise and Goban Spur, as well as

two deep sites located on Bermuda Rise and Cape Verde located in northern to the equatorial

North Atlantic Ocean basin. Several lines of evidence support the idea that eNd values recorded in

fossil fish teeth/debris and Fe-Mn oxides represent seawater rather than later diagenetic alteration

or contamination: 1) the major change of lithology at Demerara Rise from Cenomanian-Turonian

black shales to Late Campanian-Eocene chalks is not associated with the ENd shift, 2) fossil fish

teeth/debris and extracted Fe-Mn oxides yield the same Nd ratios before, during and after OAE

2, and 3) Nd and Sr isotopic values of the residual fraction remain relatively constant across

OAE 2. Neodymium chemical extracted from Fe-Mn oxides could reflect Nd contained in the

bulk sediment rather than purely in Fe-Mn oxide coatings. However, data from this study provide

evidence that the signal extracted from Fe-Mn oxides represents the oxides: 1) REE patterns of

extracted Fe-Mn oxides are typical of Fe-Mn oxide coatings and differ from shale REE patterns,

2) major elements extracted from Fe-Mn oxides are similar to USGS Fe-Mn nodule standards

rather than continental material. Thus, fossil fish teeth/debris and extracted Fe-Mn oxide coatings

both appear to be robust archives for seawater Nd isotopes even under anoxic conditions.

Throughout most of the Late Cretaceous, sites at Demerara Rise record non-radiogenic SNd

values from shallow to bathyal depths with values ranging from -14 to -17.5. These values are

unique for the North Atlantic region. The most likely source is local input of very non-radiogenic

continental material, probably from the Guyana Shield, that was carried to the ocean by rivers.

Transmission of this surface signal to intermediate depths requires excess evaporation and

formation of a local warm, saline intermediate water referred to as the Demerara intermediate









water. The lack of stratification between the three sites provides support for local ventilation and

indicates that there was insufficient North Atlantic circulation to homogenize bottom waters.

All North Atlantic sites that contain an OAE 2 section defined by a positive 613C excursion

display a positive SNd shift that varies in size with the completeness of the record. Demerara Rise

contains the most complete sections and records an increase of 8 ENd units. Peak values are

similar to Late Cretaceous ENd values observed elsewhere in the North Atlantic and the Tethys

(Puceat et al., 2005; Soudry et al., 2004). The magnitude of the positive SNd excursion at the

other sites ranges from ~1 to 3 ENd units. The correlation between 613C and SNd excursions

implies that both proxies are recording conditions fundamental to the formation of OAE 2. The

widespread distribution of sNd shift implies that oceanic changes associated with the shift were

basin-wide. Three possible interpretations of the ENd data were evaluated: 1) a change in Nd input

from the continents; 2) hydrothermal input of Nd associated with the formation of the Caribbean

LIP; and 3) reorganization of basin-wide deep ocean circulation.

The first hypothesis would require less input from the continent during OAE 2, which is

inconsistent with models of an accelerated hydrological cycle during the thermal maximum. It

would also require very rapid short term changes in continental weathering. The positive SNd

shifts observed at OAE 2 could be attributed to Nd sourced from the Caribbean LIP; however,

the timing of this event has not been exactly constrained to the timing of the OAE 2. Moreover,

this scenario would require development of anoxia, as recorded by 613C, prior to transmission of

the Nd signal. Higher resolution records are necessary to test this lead/lag relationship, but initial

results indicate that the records shift simultaneously or that eNd leads slightly. Finally, a major

change in water mass circulation in the North Atlantic could have affected the entire water

column, accounting for the 613C shift (surface process) and Nd isotopes (deep process). This









change could have been caused by enhanced circulation with Pacific deep water associated with

the opening of the EAG separating the North and South Atlantic Ocean basins. The PNd peak at

Demerara also suggests a brief mixing or a replacement of the DIW with water from the larger

North Atlantic circulation system during the PNd peak at OAE 2, possibly due to the freshening of

surface water. Thus, this model suggests that enhanced circulation, rather than stagnation

accompanied the event. Additional evaluation of the LIP and of the circulation models is

required. This could include additional Nd isotopic analyses in the Pacific and in the WIS, as

well as trace metal analyses at Demerara Rise in order to further test the role of the Caribbean

LIP in the formation of OAE 2. Neodymium values from deep South Atlantic sites are needed to

evaluate the opening of the EAG and its relationship to OAE 2, assuming that PNd values of the

South Atlantic can be distinguished from those of the Tethys.

General Late Cretaceous circulation patterns based on PNd data indicate that the Tethys

Seaway or the South Atlantic were the major sources of deep water for most of this interval with

a small contribution from the Pacific. From the Albian to late Cenomanian, the North Atlantic

was fed by a main water mass with SNd values similar to those of the Tethys Ocean, indicating

sinking of warm, saline Tethys-derived water into the North Atlantic. The mixing zone between

Tethys and Pacific deep waters was located in the western boundary of the North Atlantic. The

deep opening of the EAG between the North and South Atlantic appears to start in the Turonian-

Coniacian causing the reorganization of oceanic circulation in both basins. By the Campanian,

the EAG was fully open and North Atlantic SNd values indicate basin-wide homogenization of

the deep waters probably sourced from the South Atlantic with restricted influence of Pacific

water.









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BIOGRAPHICAL SKETCH

Elodie Bourbon was born in Briangon in the Hautes Alpes, France. Her primary education,

elementary through high-school, was completed in Briangon, France. She became interested in

geology after taking the geology course taught by Raymond Cirio her first year of high school.

He made her discover the geology of the Alps through field trips around Briangon and to Corsica

for a week. She knew that when it was time to go to college she would study geology and

become as passionate as he was. She started the bachelor degree of "Sciences de la Terre, de

l'Univers et de l'Environement" at the Universite Joseph Fourier in Grenoble, France, which has

an excellent geology program and was still located in the Alps. Her second year, she applied to

the exchange program of the University and went to complete her last year of the bachelor's

degree at the University of Florida. At UF, her research focused on Late Cretaceous oceanic

circulation in the North Atlantic using Nd isotopes, under the guidance of Dr. Ellen Martin. After

completion of the Master of Science degree, Elodie plans on working for an environmental

consulting firm in New York and eventually goes back to school for a PhD. in a few years.





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1 NEODYMIUM ISOTOPES THROUGHOUT THE NORTH ATLANTIC IN THE LATE CRETACEOUS AND ACROSS THE OCEANIC ANOXIC EVENT 2 By LODIE BOURBON A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2008

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2 2008 lodie Bourbon

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3 To my parents, Johan, Thomas and Nala.

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4 ACKNOWLEDGMENTS I would like to sincerely thank Dr. Ellen Martin f or her con tinued guidance on this project. She is a great mentor, a pleasure to work with and a good friend. I would al so like to thanks my committee members Dr. David Hodell, Dr. Geor ge Kamenov and Dr. Philip Neuhoff for their advice and review of this thesis. Thanks also to Dr. Kenneth MacLeod and Dr. Alvaro Jimenez Berocosso from the University of Missouri for their advice and review of this thesis as well as for providing some of the samples. I would also like to thanks Brian Huber for providing some of the Blake Nose samples. I am also very grateful for the financial s upport that was provided by the NSF SGR grant awarded to Dr. Ellen Martin, the Department of Geological Sciences, and Graduate Student Council. Special thanks go to Derrick Newkirk a nd Chandranath Basak for their guidance and continuous help in the lab at the beginning of my graduate ca reer. I would like to thank Dr. George Kamenov for his assistance in the lab a nd help with analysis and the many others who have helped me in the laboratory. Finally, I would like to thank my family and friends. Thanks go to Odile Girod, Christian Bourbon and to my two brothers Johan and Thom as for their unfaltering love and support. Thanks go to Joris Barjhoux, Emmanuelle Bric he and Emmanuelle Valer for being very supportive and great friends since elementary and middle schools. Thanks go to Michael Ritorto for his never ending love, encouragement, and s upport throughout this pro cess. Thanks go to my many wonderful friends in the Department of Geological Science at UF, especially Goke Atalan, Mary Beth Day, Laura Gregory, A bby Langston, Kelly Probst and Laura Ruhl.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ............................................................................................................... 4LIST OF TABLES ...........................................................................................................................7LIST OF FIGURES .........................................................................................................................8ABSTRACT ...................................................................................................................... .............11 CHAP TER 1 INTRODUCTION .................................................................................................................. 132 BACKGROUND ....................................................................................................................18Archives of Neodymium Isotopes .......................................................................................... 19Late Cretaceous Climate and Paleoceanography .................................................................... 21Equatorial Atlantic Gateway ........................................................................................... 22Albian to Cenomanian ..................................................................................................... 23CTBI-Santonian ............................................................................................................... 24Campanian-Maastrichtian ................................................................................................25Oceanic Anoxic Events ...........................................................................................................26Ocean Anoxic Event 2 ..................................................................................................... 26Mid-Cenomanian Event ...................................................................................................28Description of Sample Sites ................................................................................................... .29Demerara Rise Transect ..................................................................................................29Blake Nose Transect ........................................................................................................31Goban Spur Transect .......................................................................................................33Bermuda Rise ..................................................................................................................35Cape Verde ......................................................................................................................363 MATERIALS AND METHODS ...........................................................................................45Samples Preparation ........................................................................................................... ....45Fossil Fish Teeth and Debris Preparation ........................................................................ 45Ferromanganese Oxide Coating Preparation ................................................................... 45Silicate Residues Preparation .......................................................................................... 47Columns Ch emistry ............................................................................................................. ...47Neodymium Analysis ............................................................................................................ .48Strontium Analysis ............................................................................................................ .....49Rare Earth Elements Analyses of Fossil Fish Teeth and Fe-Mn Oxide Coatings .................. 49Major Elements Analyses of Fe-Mn Oxide Coatings ............................................................. 50

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6 4 RESULTS ....................................................................................................................... ........52Neodymium Results ............................................................................................................. ...52Demerara Rise Transect ..................................................................................................52Blake Nose Transect ........................................................................................................54Goban Spur Transect .......................................................................................................55Bermuda Rise ..................................................................................................................57Cape Verde ......................................................................................................................58Rare Earth Elements Plots ..................................................................................................... .58Sequential Extraction Results ................................................................................................. 59Major Elements Ratios ...........................................................................................................605 DISCUSSION .................................................................................................................... ...112Seawater Signal ....................................................................................................................112Demerara Rise ......................................................................................................................114Ocean Anoxic Event 2 .......................................................................................................... 115Implication for the Cause of OAE 2 .............................................................................. 1161.Continental sources ............................................................................................. 1162.Caribbean large igneous province ...................................................................... 1173.Oceanic circulation .............................................................................................119Late Cretaceous North Atlantic Circulation ......................................................................... 122Late Aptian-Cenomanian ............................................................................................... 122Turonian ...................................................................................................................... ..124Coniacian-Santonian ...................................................................................................... 124Campanian-Maastrichtian ..............................................................................................1246 CONCLUSIONS .................................................................................................................. 132LIST OF REFERENCES .............................................................................................................135BIOGRAPHICAL SKETCH .......................................................................................................147

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7 LIST OF TABLES Table page 3-1 Average of 147Sm/144Nd measured at the different sites. ...................................................514-1 Demerara Rise Nd isotopic values from Fossil Fish Teeth from ODP Sites 1258, 1260 and 1261.. ..................................................................................................................624-2 Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site 1258 at Demerara Rise. ...................................................................................................... 734-3 Blake Nose Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Sites 1049, 1050 and 1052. .............................................................................. 754-4 Goban Spur Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Sites 549, 550 and 551. .................................................................................... 834-5 Bermuda Rise Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site 386. ............................................................................................894-6 Cape Verde Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site 367............................................................................................................. 934-7 REE values extracted from Fe-Mn oxide samples and normalized to PAAS from USGS Standards and ODP Site 367, 386, 550, 1049, 1050, 1052, 1258 and 1260. .......... 964-8 REE values of uncleaned fossil fish t eeth normalized to PAAS from ODP Site 367, 386 and 1260. ...................................................................................................................1014-9 Nd and Sr isotopic values from fossil fish teeth and Fe-Mn oxide coatings and residual fraction from ODP Site 1260 at Demerara Rise. ................................................ 1054-10 REE values of Fe-Mn oxide coatings and residual fraction normalized to PAAS from ODP Site 1260 at Demerara Rise. ....................................................................................1074-11 Major elements rations of Fe-Mn oxide coatings from Sites 367, 386, 550, 1049 and 1052..................................................................................................................................1094-12 Major elements rations of fish teeth/debris from Sites 549, 1050, 1052, 1260 and 1261..................................................................................................................................111

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8 LIST OF FIGURES Figure page 2-1. Summary of major geochemical, tectonic a nd sea lev el associated with mid-Cretaceous oceanic anoxic events (OAEs) ........................................................................................... 382-2 Plate recons truction: 80 Ma. ............................................................................................. 392-3 Compilation of global benthic foraminiferal 13C and 18O record based on data from the Late Cretaceous ............................................................................................................402-4 Present-day locations of ODP and DSDP study sites ........................................................ 412-5 Paleogeographic map indicating the estimat ed location of the study sites in a plate tectonic reconstruction ge nerated for the CTBI .................................................................412-6 Location of ODP Leg 207 sites on Deme rara Rise with modern bathymetry ................... 422-7 Stratigraphic range of the Late Creta ceous sedimentary succession and major breaks in sedimentation of Sites 1258, 1260 and 1261 .................................................................422-8 Location of the ODP Leg 171B dr illing transect on Blake Nose ......................................432-9 Interpretation of seismologic section for Blake Nose, Leg 171B ...................................... 432-10 Geologic section across Goban Spur s howing the sites drilled during Leg 80 .................. 442-11 Location of Site 367, DSDP Leg 41 .................................................................................. 444-1 Nd(t) values plotted versus meter composite depth (mcd) across the Late Cretaceous from ODP Sites 1258 at Demerara Rise. ........................................................................... 664-2 Nd(t) values plotted versus meter composite depth (mcd) across the Late Cretaceous from ODP Sites 1260 at Demerara Rise. ........................................................................... 674-3 Nd(t) values versus depth (mcd) across the Late Cretaceous from ODP Sites 1261 at Demerara Rise. ...................................................................................................................674-4 Nd(t) values versus age across the Early Pa leogene and Late Cretaceous from ODP Sites 1258 (3192 m), 1260 (2549 m) and 1261 (1899 m) at Demerara Rise. .................... 684-5 Nd(t) values versus age across OAE 2 and MCE from ODP Sites 1258 (3192 m), 1260 (2549 m) and 1261 (1899 m) at Demerara Rise. ...................................................... 694-6 Nd(t) values versus age across OAE 2 from ODP Sites 1258 (3192 m), 1260 (2549 m) and 1261 (1899 m) at Demerara Rise. ............................................................................... 70

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9 4-7 Nd(t) and 13C values versus depth (mcd) across OAE 2 (blue box) and MCE (purple box) from ODP Site 1260... ............................................................................................... 714-8 High resolution Nd(t) and 13C values versus composite depth across OAE 2 from ODP Sites 1258, 1260 and 1261. .......................................................................................724-9 Plot of Nd(t) values versus age before, during and after OAE 2 from ODP Site 1258 at Demerara Rise. ............................................................................................................. ..734-10 Fe-Mn oxide coating REE patterns fr om ODP Site 1258 at Demerara Rise. .................... 744-11 ODP Sites 1049 at Blake Nose: Nd(t) versus depth (mcd) across the Late Cretaceous. ....794-12 ODP Sites 1050 at Blake Nose: Nd(t) versus depth (mcd) across the Late Cretaceous. ....794-13 ODP Sites 1052 at Blake Nose: Nd(t) versus depth (mcd) across the Late Cretaceous. ....804-14 Nd(t) values versus age (Ma) across the Late Cretaceous and early Cenozoic from ODP Sites 1049, 1050 and 1052 at Blake Nose................................................................. 814-15 Nd(t) and 13C of benthic foraminifera (Huber et al., 1999) values versus depth across OAE 2 from ODP Site1050 at Blake Nose. .......................................................................824-16 ODP Site 549 at Goban Spur: Nd(t) values versus depth acro ss the Late Cretaceous. ....... 864-17 ODP Site 550 at Goban Spur: Nd(t) values versus depth acro ss the Late Cretaceous ........ 864-18 ODP Site 551 at Goban Spur: Nd(t) values versus depth acro ss the Late Cretaceous. ....... 874-19 Nd(t) and 13C (bulk sediment, Gustafsson et al., 2003) values versus depth across OAE from ODP Site 551 at Goban Spur.. ......................................................................... 884-20 Nd(t) values across the Late Cretaceous from ODP Site 386 at Bermuda Rise.. ............... 914-21 Nd(t) and 13Corg (MacLeod et al., unpublished data) values across the OAE 2 from ODP Site 386 at Bermuda Rise. .........................................................................................924-22 Nd(t) values versus depth across the Late Cretaceous from ODP Site 367 at Cape Verde.. ....................................................................................................................... .........944-23 Nd(t) and 13C values versus depth across the OAE 2 at ODP Site 367 at Cape Verde. ....954-24 Fe-Mn oxide coating REE patterns from ODP Site 1049 at Blake Nose .......................... 994-25 Fe-Mn oxide coating REE patterns from ODP Site 1050 at Blake Nose.. ........................ 994-26 Fe-Mn oxide coating REE patterns from ODP Site 1052 at Blake Nose. ....................... 100

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10 4-27 REE plots of the average values from Fe-Mn oxide coatings from ODP Sites 367, 386, 550, 1049, 1050, 1052, 1258 and 1260.. ..................................................................1004-28 Fish teeth REE patterns from ODP Site 367 at Cape Verde. ...........................................1034-29 Fish teeth REE patterns from ODP Site 386 at Bermuda Rise. ....................................... 1034-30 Fossil fish teeth REE patterns fr om ODP Site 1260 at Demerara Rise. .......................... 1044-31 Nd(0) from fossil fish teeth and Fe-Mn oxide coatings and residual fraction from ODP Site 1260 at Demerara Rise. ............................................................................................. 1064-32 87Sr/86Sr values from sequential extraction samples. ....................................................... 1064-33 Fe-Mn oxide coatings REE patterns fr om ODP Site 1260 at Demerara Rise.. ............... 1084-34 Silicate residues REE patterns from ODP Site 1260 at Demerara Rise. ......................... 1085-1 Compilation of Nd(t) values across the Late Cretaceous in the North Atlantic, Pacific and Tethys. .......................................................................................................................1265-2 Pre-OAE 2 Nd values and maximum values reached during OAE 2 at ODP Sites 367, 386, 551, 1050, 1258, 1260 and 1261. .....................................................................1275-3A Albian to Cenomanian paleogeog raphic map of the North Atlantic ................................1285-3B Cenomanian-Turonian Boundary Interval paleogeographic map of the North Atlantic. ..................................................................................................................... .......1295-3C Turonian paleogeographic map of the North Atlantic ..................................................... 1305-3D Campanian-Maastrichtian paleogeog raphic map of the North Atlantic .......................... 131

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11 Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Sciences NEODYMIUM ISOTOPES THROUGHOUT THE NORTH ATLANTIC IN THE LATE CRETACEOUS AND ACROSS THE OCEANIC ANOXIC EVENT 2 By lodie Bourbon August 2008 Chair: Michael R. Perfit Major: Geology The Cenomanian/Turonian boundary coincide s with the Late Cretaceous thermal maximum, the formation of the Caribbean La rge Igneous Province (LIP) and Oceanic Anoxic Event 2 (OAE 2), which represents a dramatic perturbation of the globa l carbon cycle. Late Cretaceous oceanic circulation in the North Atlantic is poorly known, yet it could be important for understanding the dynamic conditions that le d to OAE 2. Neodymium isotopic compositions of fossil fish teeth/debris and Fe-Mn oxide coatings from Ocean Dr illing Program sites on Demerara Rise, Blake Nose, Bermuda Rise, Cape Verde and Goban Spur were used to reconstruct the evolution of North Atlantic deep ocean circulation in the Late Cretaceous and investigate the relationship between ocean circulation and the formation of OAE 2. All of the sites with positive 13C excursions at OAE 2 also record a positive Nd shift, which varies from ~1 to 8 Nd units depending on the completene ss of the record. Extractions of Nd from dispersed Fe-Mn oxide coatings from samples before, during and after the excursion yield Nd values that are consistent with data from fi sh teeth apatite, indicating that both mineral phases are robust archives for Nd isotopes in a range of lithologies and redox conditions. Nonradiogenic Nd values ranging from -14 to -17.5 and a lack of st ratification in Nd observed at the Demerara Rise depth transect site s suggest local ventilation of wa rm, saline water, referred as to

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12 the Demerara intermediate water (DIW), to intermediate depths. This water mass appears to have delivered a very non-radiogenic Nd signal, presumably from a local riverine source draining from the Guyana Shiel d, to intermediate depths con tinuously from the late AlbianCenomanian to the late Maastrichtian with a brief interruption during OAE 2. The ~6 to 8 Nd unit peak at Demerara Rise during OAE 2 suggest s DIW may have shut down over this interval, possibly due to an enhanced hydrologic cycle. Apparently this local bottom water source mixed with or was replaced by water fr om the larger North Atlantic circulation system. Widespread distribution of positive Nd shifts during OAE 2 throughout th e North Atlantic implies OAE 2 formation was associated with a basin-wide pr ocess such as 1) hydrot hermal input of Nd associated with the formation of the Caribbean LIP and/or 2) reorganization of deep oceanic circulation. Yet, Nd isotopic data do not uniquely distinguish betw een these scenarios and further analyzes are required. General Late Cretaceous circulation patterns based on the distribution of Nd data indicate that the Tethys Seaway was the major source of deep water in the No rth Atlantic during the Albian and Cenomanian. Ne odymium values in the western Nort h Atlantic represent a mixture of less radiogenic Tethys and more radiogenic Pacific waters and ar gue against sluggish conditions. Nd and oxygen isotopic data suppor t the initial opening of the Equatorial Atlantic Gateway between the North and South Atlantic in the Tur onian-Santonian that allowed the introduction of cooler, South Atlantic deep waters with Nd values of ~-9. Finally, Nd values at Demerara Rise shift from unique non-radiogenic background values to more Atlantic-like values in the mid to late Maastrichtian suggesting the end of cond itions necessary for formation of the DIW.

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13 CHAPTER 1 INTRODUCTION The Late Cretaceou s was the warmest greenhouse interval in the la st 150 Ma (Jenkyns et al. 1994) and included major perturbations to the global carbon cycle referred to as oceanic anoxic events (OAEs). OAEs are characterized by large-scale burial of organic carbon, positive 13C excursions in organic and carbonate carbon and widespread deposition of laminated black shales (e.g., Schlanger and Jenkyns, 1976; Arthur et al., 1987). Evidence for deep sea and surface anoxia/dysoxia also includes biot ic extinctions (e.g., Huber et al., 2002) and the discovery of biomarkers from green sulfur bacteria during several OAEs (Kuypers et al., 2004). The most prominent and widespread of Late Cretaceous OAEs is OAE 2, which occurred at the Cenomanian-Turonian boundary (Schlanger a nd Jenkyns, 1976; Jenkyns, 1980, Arthur et al., 1988), a time that coincides with the peak of the Cretaceous greenhouse climate (e.g., Frakes, 1994; Huber et al., 2002; Wilson et al., 2002), em placement of the Caribbean large igneous province (LIP) (e.g., Sinton and Duncan, 1997), and a sea level highstand (Haq et al., 1988). The cause of OAE 2 is still debated with inte rpretations ranging from surface processes that generated enhanced surface productivity and de cay of the resulting organic matter to deep processes, such as stagnant circulation a nd reduced ventilation that produced warm, oxygen depleted bottom waters. Yet, data on Late Cret aceous intermediate and bottom water circulation in the North Atlantic, which could potentially discriminate between th ese two mechanisms, is lacking. Neodymium isotopes provide a way to track water masses and pale ocirculation patterns (Frank, 2002; Goldstein and Hemming, 2003) and coul d be use to evaluate whether or not OAE 2 was associated with changes in deep ocean ci rculation, and to constrain Late Cretaceous deep water circulation in general. The residence time of Nd in seawater is about 1000 years (Jeandel et

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14 al., 1995), which is shorter than the mixing tim e of the oceans (~1500 yrs) (Goldstein and Hemming, 2003). Neodymium is main ly supplied to the oceans via continental weathering and runoff of dissolved and particulate fluxes (Bertram and Elderfield, 1993; Frank, 2002; Goldstein and Hemming, 2003). As a result, Nd isotopes are quasi-conservative tracers of water mass that reflect the initial signal of th e source region and are only sligh tly modified by weathering inputs along the flow path. Different oceanic basins have a characteristic Nd ( Nd = [(143Nd/144Nd)sample/(143Nd/144Nd)CHUR-1] x 104 expressed in -units) isotopic si gnature depending on the surrounding terrains. Within a basin, Nd values also vary ver tically within the water column recording different water masses (Piepgras and Wasserburg, 1987; Bertram and Elderfield, 1993, Jeandel et al., 1995; Goldst ein and Hemming, 2003). Neodymium isotopes are found in fossils fish teeth/debris an d Fe-Mn oxide coatings acquire the Nd signature of the surrounding water during the early diagenesis (E lderfield and Pagett, 1987; Martin and Scher 2004; Haley et al., 2004; Gutjahr et al., 2007). Thus, Nd contained in these two phases offers an effective means to track bottom water circulation. Initial results from a study of Nd isotopes on Late Cretaceo us fossil fish teeth/debris from Demerara Rise, a tropical site in the North Atlantic, revealed a dramatic Nd excursion that coincides with OAE 2 (Blair, 2006) as defined by 13C (Erbacher et al., 2005). Blair (2006) documented very non-radiogenic Nd values (-14 to -16) on Demerara Rise in the Late Cretaceous that increased dramatically to -8 Nd units during OAE 2 before returning to the preOAE 2 values. In contrast, western North Atlantic values for the same time interval ranged from -5 to -8.5 for the Late Cretaceous (Blair, 2006); Ce ntral Pacific values ranged from -2.5 to -5.5 (Frank et al., 2005, Blair, 2006) a nd Tethys values ranged from -6 to -11.5 (Stille et al., 1990; Soudry et al., 2006; Pucat et al., 2005). The non-radiogenic values observed at Demerara Rise

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15 are also much lower than any values reported for major Cenozoic water masses, which range from -3 in the Pacific to -13.5 in the North Atlantic (e.g. Burton et al., 1997, 1999; Frank, 2002; Scher and Martin, 2004). Blair ( 2006) proposed that these unique values might reflect inputs from local sources, such as the neighboring Trans-Amazonian Prot erozoic Shield or the Archean Guiana Highland. The pilot study by Blair (2006) al so tested the integrity of Nd isotopic analyses on fossil fish teeth and Fe-Mn oxide coat ings using Sr isotopes and rare earth elements (REE). Blair (2006) demonstrated that Fe-Mn oxide coatings extracted from marine sediments are representative of the deep s eawater composition rather than diagenetic alteration, and are effective archives of deep sea Nd isotopes on Cenozoic to Cretaceous timescales. Thus, the correlation between the Nd and carbon isotopes suggested that changes in Nd, such as introduction of a new source of Nd or a distinct deep water circulation pa ttern coincided with the formation of OAE 2. Proposed mechanisms for OAE 2 that were consistent with the Nd data from the Oceanic Drilling Program (ODP) Site 1258 at Demerara Rise include: 1) a change in the intensity or composition of continental input 2) eruption of the Ca ribbean LIP, and 3) enhanced oceanic circulation and upwelling (MacLeod et al., submitted). Each of these interpretations provided testable pr edictions about th e distribution of Nd through time and space in the Late Cretaceous. In terms of weathering input, the seawater Nd signal at Demerara Rise could change without a circulation change if the quantity or the composition of the weathered material changed, introducing a new source of Nd with less radiogenic values to the system (MacLeod et al., submitted). This change would need to occur relatively rapidly and to be reversible, which does not seem to reconcile with the time scale of continental weatheri ng. Enhanced weathering

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16 would be accompanied by an increasing nutri ent flux to the ocean, promoting surface productivity, and thus leading to anoxia (Erb acher, 2004). In this model, we should obtain different Nd responses at different locations de pending on the geology of the surrounding terrains. Also, we would expect to see a negati ve rather than positive shift associated with weathering inputs at Demerara Rise sin ce the local inputs have non-radiogenic Nd values. The timing of the eruption of the Caribbean LIP, which was one of the major LIP events for that period, coincided with the Cenoman ianTuronian boundary (Alvarado et al., 1997; Sinton et al, 1998; Hauff et al. 2000). Sinton and Duncan ( 1997) suggested that surface water fertilization by metal-rich buoyant hydrothermal plumes relate d to the Caribbean LIP event created a bloom of surface productivity. Oxidation of this organic matter and of reduced species from the hydrothermal effluent could have depl eted the oceanic oxygen reservoir. Hydrothermal circulation through this basaltic province also might have intr oduced radiogenic Nd into the ocean. In todays oceans Nd re leased by hydrothermal vents is quantitatively removed by oxide formation at the ridge (e. g. Halliday et al ., 1992 and Sinton and Duncan, 1997). However, under anoxic conditions, radiogenic Nd from the LIPs may have been transported farther away. This scenario would imply that the anoxia, defined by the 13C shift, would need to occur prior to Nd shift in order to allow the transport of the Nd signal away from the LIP. In addition, similar positive shifts should occur throughout the North Atlantic, possibly with decreasing magnitude with distance from the Caribbean LIP. The enhanced circulation hypothesis is ba sed on the convergence of Demerara Rise Nd values with Nd values in the western North Atlantic a nd Tethys (Blair, 2006; Pucat et al., 2005; Soudry et al., 2006) during the OAE 2 peak, sugges ting that the deep ocean was involved in the formation of OAE 2, but that enhanced circulatio n, rather than stagnation accompanied the event

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17 (Blair, 2006). Thus, a change in intermediate and deep water sources or water masses mixing could have occurred at that ti me. Wind-driven upwelling would increase the nutrient flux to the surface, promoting productivity and thus anoxia. However, mechanisms that would lead to the change in circulation and the link between productivity and deep circulation are not completely understood yet. If enhanced mixing between the DIW and the North Atlantic water mass occurred, other North Atlantic sites would be expected to shift toward less radiogenic Nd values during OAE 2. In contrast, if the Nd shift at De merara Rise results from the removal of the nonradiogenic source, other North Atlantic sites might not display a Nd shift associated with the event (MacLeod et al., submitted). Documented changes in Nd isotopes at Demerara Rise indicate that deep circulation played a role in the development of OAE 2, but additional data are needed to evaluate overall circulation patterns in the North Atlantic throughout th e Late Cretaceous and determine how deep circulation impacted conditions during OAE 2. This study compiled Late Cretaceous Nd data of fossil fish teeth/debris and Fe-Mn oxide coatings from additional Demerara Rise ODP Sites and several other ODP Sites throughout the North At lantic, two other depth transects from upper bathyal to abyssal depths at Blake Nose and G oban Spur, and two deep sites at Bermuda Rise and Cape Verde. These data are then used to ev aluate each of the scen arios for OAE 2 described above and to develop an understand ing of basic intermediate and deep water circulation patterns through the Late Cretaceous in the North Atlantic.

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18 CHAPTER 2 BACKGROUND Neodym ium is a light Rare Earth Element (REE). It has seven stable isotopes. Radiogenic 143Nd is produced by the alpha decay of 147Sm which has a half life of ~1.06 x 10-11 years. Hence, the abundance of 143Nd and the ratio of 143Nd/144Nd have increased with time. The relationship between the measured 143Nd/144Nd and the initial 143Nd/144Nd is described by the following equation: with = 6.54 x 10-12 y-1. The isotopic evolution of Nd on Earth is described by the Chondritic Uniform Resevoir (CHUR) model (DePaolo and Wa sserburg, 1976a). It is possible to calculate 143Nd/144Nd of CHUR at any time in the past: where It CHUR is the ratio of 143Nd/144Nd at a given time (t), I0 CHUR is the present value of 143Nd/144Nd (0.512638) and 147Sm/144Nd is the present value of CHUR based on meteorites (0.1967). Throughout the thesis, Nd isotopic ratios will be presented using the epsilon notation ( Nd) which expresses Nd isotopes as the deviation from bulk Ea rth values in part per 104: In the long term, Nd is preferentially pa rtitioned into the liquid phase during partial melting of the mantle; as a result old crustal rocks have a lower 147Sm/144Nd ratio than bulk Earth and volcanic rocks have a higher 147Sm/144Nd ratio than bulk Earth. This is expressed by a

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19 negative Nd, which varies from 0 to -50. In contrast, a positive Nd indicates that the rocks are derived from melting of the mantle, such as mid-oceanic ridge and ocean island basalts, which have Nd values varying from 0 to + 12 (Piepgras and Wasserburg, 1980). Archives of Neodymium Isotopes The concentration of Nd in seawater is low, ~4pg/g; however, fossil fish rem ains and authigenic Fe-Mn oxides concentrate and record s eawater values, thereby providing archives that can be used to track water masses and paleo-ci rculation patterns. Ferromanganese oxide crusts and nodules have high Nd concentrations of ~100 ppm. Previous studies have shown that Fe-Mn oxide crusts record deep wa ter Nd values through time (Albarede and Goldstein, 1992; Abouchami et al., 1997; Burton and Ling, 1997; Frank and ONions, 1998, Frank et al., 2002; Van de Fierdt et al., 2004; Gutjahr et al., 2007). Fe -Mn crusts have been used to compile records of long-term trends and variations in ocean ci rculation over much of the Cenozoic. However, their growth rate is quite slow, ranging from 1 to 15 mm/M a (Segl et al., 1984; Puteanus and Halback, 1988); thus, these archiv es produce a low resolution reco rd of changes through time, and rapid shifts in circulation po tentially associated with clima tic events may not be preserved. These crusts are typically dated using Be isotopes, which is problematic for samples older than 10 Ma because the half-life of 10Be is 1.5 x 106 years. Moreover, crusts ha ve a sparse distribution and only grow in environments with very sl ow sedimentation rates, which inhibit high resolution. More recently, dispersed authigenic Fe-Mn oxides coatings on marine sediment were shown to record the contemporaneous seawater composition and thus are suitable for Nd isotopic analyses (Rutberg et al., 2000; Bayon et al., 2002; Piotrowski et al., 2004; Blair, 2006). These authigenic coatings are made of the same material that is concentrated in the Fe-Mn crusts and nodules, but they can be dated with surr ounding sediment using biostratigraphic,

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20 magnetostratigraphic and chemostratigraphic techni ques. However, they cannot be physically separated, thus a sequential leaching procedure is required to extract the Nd from the Fe-Mn oxide fraction (Rutberg et al., 2000; Bayon et al., 2002; Piotrows ki et al., 2004; Blair, 2006). Fish remains are also effective archives fo r Nd (Staudigel et al., 1985; Elderfield and Pagett, 1986; Martin and Haley, 2000; Thomas et al., 2003; Martin and Scher 2004; Thomas, 2004; Scher and Martin, 2006). Alth ough the hydroxyapatite teeth of living fish contain a few ppb of Nd, the hydroxyfluorapatite of fossil fish teeth contain between 100 and 1000 ppm Nd. (Wright et al., 1984; Shaw and Wasserburg, 1985; Staudigel et al., 1985; Martin et al., 1995, Martin and Haley, 2000; Martin and Scher, 2004). This Nd is incorporated into fossil fish remains during early diagenesis when they are often still in contact with deep ocean water (Elderfield and Pagett, 1986; Martin and Scher 2 004). Fossil teeth are found in all ocean basins and they record detailed variati ons in the deep water signal thr ough time. In addition, they can be dated with the surrounding sediment using biostratigraphic, ma gnetostratigraphic and chemostratigraphic techniques. Several general lines of eviden ce support the idea that fossil fish remains and Fe-Mn oxide coatings preserve a record of the deep water si gnal through time: 1) Fish remains, Fe-Mn oxide coatings, and crust deposited in similar water masses yield identical isotopic ratios within error and without any systematic bias (Martin and Ha ley, 2000; Blair, 2006); 2) teeth exposed to the same water masses, but in different locations, l ithologies and pore fluids record similar isotopic ratios (Martin and Haley, 2000); 3) the concentration of Nd in th e teeth does not systematically increase with burial depth or age (Bernat, 1975 ; Staudigel et al., 1985, Ma rtin, unpublished data), and 4) higher Nd concentrations are observed in teeth exposed to seawater longer because they were deposited in slow sedimentation areas (Eld erfield and Pagett, 1986; Staudigel et al., 1986;

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21 Martin and Scher, 2004). Since Nd is highly reactive, it occurs in extremely low concentrations in pore fluids. Therefore, very little Nd is available for incorporation or exchange once the teeth/debris or Fe-Mn oxide coatings are no longer in comm unication with seawater. Late Cretaceous Climate and Paleoceanography The Late Cretaceou s was the most intense greenhouse interval in the last 150 Ma (Jenkyns et al. 1994). This warm climate was characterized by atmospheric CO2 concentrations 3 to 16 times greater than modern levels (Baron and Peterson, 1990, Bice and Norris, 2002; Bice et al., 2006) and a low equator to pole temperature grad ient (Huber et al., 1995; Huber et al., 2002; Bice et al., 2003, 2006). This interval of time also experienced a worl dwide pulse in ocean crustal production including the emplacement of la rge igneous provinces (LIPs) in the Caribbean (Larson, 1991) at the Cenomanian/Turonian bou ndary interval (CTBI) (Alvarado et al., 1997; Sinton et al, 1998; Hauff et al. 2000). In response to therma l expansion and crustal production, global sea level rose to the highest level of the past 250 Ma, peaking in the early to middle Turonian (Haq et al., 1988) (F igure 2-1). High sea level conditi ons led to extensive areas of epicontinental seas, including the Western Interior Seaway in the United States (Hay et al., 1993). The North Atlantic was a young growing basin lo cated in tropical to subpolar latitudes (Figure 2-2). It had evolvi ng connections to Tethys in the east, to the South Atlantic to the south, and to the Pacific to the west. The conditions necessary for the North Atlantic Deep Water (NADW) production or formation had not develope d yet. Late Cretaceous oceanic circulation has been modeled (e.g., Barron and Peterson, 1980; Barron et al., 1993, 1995), but is difficult to constrain. Surface water masses entering the North A tlantic Ocean were derived from the Tethys Ocean and/or the Pacific Ocean by the Tethyan circumglobal current flowing around the equator

PAGE 22

22 (Stille et al., 1996; Pucat et al ., 2005). In contrast, deep circulat ion in the North Atlantic during the Late Cretaceous is not well known. Equatorial Atlantic Gateway The deep opening of the Equa torial Atlantic Gateway (EAG) between the North and South Atlantic Ocean basins in the Late Cretaceous caus ed a major reorganization of deep oceanic circulation and evolution of be nthic and planktic biota. (Mac Leod and Huber, 1996; Frank and Arthur, 1999; Poulsen et al., 2001, 2003; Kuypers et al., 2002; Fr ank et al., 2005; Isaza-Londono et al., 2006). However, the exact timing of a de ep water connection between the North and South Atlantic through the EAG is still debated. Paleomagnetic methods only provide limited constrains because of the low latitude position of the EAG and the lack of magnetic lineation in the mid Cretaceous. Estimates for the deep water connection range from in the early Turonian to the early Campanian (Tucholke and Vogt, 1979; Summerhay es, 1981; Wagner and Pletsch, 1999; Pletsch et al., 2001; Kuypers et al., 2002). Pletsch et al. (2001) placed th e opening of the EAG in the early Turonian using a complilation of published sedimentologic, mineralogic, micropalaeontologic and geochemical data from th e northern Gulf of Guinea. In addition, levels of carbonate saturation were diffe rent among different oceanic basins in the Albian, but they converged near the CTBI (Arthu r et al., 1985), which might refl ect greater connection between basins. Proponents of this earli er opening argue that erosive d eepwater currents created by the exchange between North and South Atlantic ba sins caused widespread hiatuses observed in Atlantic sections, including many of the sites st udied in this project (Wagner and Pletsch, 1999). Coupled ocean-atmosphere model simulations also suggest oceanographic changes related to the gateway event that could have contributed to the development of the Cretaceous thermal maximum at the CTBI (Poulsen et al., 2001, 2003).

PAGE 23

23 Friedrich et al. (2007) compiled published Late Cretaceous 18O data from the North and South Atlantic, Pacific, Indian a nd Southern Oceans (Figure 2-3) that appears to indicate that deep opening of the EAG started in the Tur onian (~90 Ma) and was completed by the late Santonian to Campanian (~84 Ma). They suggested that the general cooling trend from the late Turonian to Campanian is related to the opening of the EAG and to reorganization of oceanic deep circulation. The EAG was fully opened in the early Campanian, introducing oxygenated deep waters into the North Atlant ic that resulted in the transiti on from black shales to oxygenated chalk observed at Demerara Rise. In contrast, Frank et al. (1999) suggest that the deep circulation between the North and South Atlantic is linked to the subsidence of the Rio Grande-Wal vis Ridge in the mid Campanian to late Maastrichtian. They propose that the deep opening of the EAG cont ributed to the latest Cretaceous global cooling trend by exporting cool intermediate and deep water from the Southern Ocean into the North Atlantic. Albian to Cenomanian Throughout the late Albian to m id Cenomania n, paleotemperature estimates for middle bathyal water masses average 16C, and tropical to subtropical sea surface temperatures (SST) ranged from 26 to 31C (Huber et al., 2002; Petr izzo et al., 2008). This period of time was associated with changes in the vertical stratifi cation of the water column in the western North Atlantic, moderately low latitudinal thermal gradients and a potential tran sition from oligotrophic to mesotrophic conditions (Wilson and Norris, 2001; Erbacher et al., 200 1; Huber et al., 2002; Petrizzo et al., 2008). At Blak e Nose, intervals of high SST correspond to periods of strong vertical stratification, whereas cooler SSTs correspond to interv als of weaker stratification (Wilson and Norris, 2001; Petrizzo et al., 2008). In the South Atlantic deep water formation occurred predominantly in the southern high la titudes (Schmidt and Mysak, 1996; Poulsen et al.,

PAGE 24

24 2001). There is evidence that deep water formation occurred in subtropical regions of the North Atlantic where excessive evaporation led to sink ing of warm, saline waters (Brass et al., 1982; Arthur et al., 1985, 1987; Barr on and Peterson, 1990; Woo et al., 1992; Barron et al; 1993; Mosher et al., 2007). CTBI-Santonian A gradual transition to a hot greenhouse cl im ate started in the mid Cenomanian and reached a maximum at the CTBI that represents the Cretaceous Thermal Maximum (Frakes, 1994; Huber et al., 2002; Wilson et al., 2002; Gust afsson et al., 2003; Forster et al., 2007). Bottom waters temperature reached an average of 19C at high latitude and low latitudes sites and stayed as high as ~17C from the Coniaci an to mid Campanian. Estimates for SST range from 31 to 42C in the tropical western Atlantic Ocean during the late Cenomanian to early Turonian (Bice et al., 2006; Forster et al., 2007 ). The thermocline was poorly developed in the western North Atlantic and surface waters were strongly mixed from the early Cenomanian to mid Campanian (Huber et al., 2002). Bottom waters li kely formed at high latitudes in the Pacific and Southern Ocean (Bice and Marotzke 2001; Schmidt and Mysak, 1996; Poulsen et al., 2001). Decreased 18O values of benthic foraminifers in the late Cenomanian indicate that bottom water salinity decreased and/or that bottom water temp eratures increased (Friedrich et al., 2006). Changes in salinity could have been related to increased precipitation associated with an accelerated hydrological cycle at the CTBI (Calvert and Peders on, 1990; Erbacher and Thurow, 1997). Associated enhanced freshwater runoff wo uld have reduced deepwater production in low latitudes (Mosher et al., 2007, MacLeod et al., submitted). In contrast, other researchers have suggested that conditions including high latitude warm bottom waters and maximum flooding of epicontinental seas were favorable for warm salin e deep water formation at low latitudes at the CTBI (Arthur et al., 1987; Huber et al., 2002). Warm saline deep water formation would have

PAGE 25

25 led to increased rates of oceanic turnover, upwel ling of nutrient-rich deep water and subsequent increased sea surface productivity (Arthur et al., 1987). Seawater Sr isotopes (Mc Ar thur et al., 2001, Jones and Jenkyns, 2001) and Mg/Ca ratio (Bice et al., 2006) were both at a minimum from the Turonian to the Coniacian, which might coincide with a maximum rate of seawater ex change through hydrothermal systems associated with the Caribbean LIPs (Jones and Jenkyns 2001, Bice et al., 2006). The most precise 40Ar/39Ar dates for the Caribbean LIPs range from 87-95 Ma (Alvarado et al., 1997; Sinton et al, 1998; Hauff et al. 2000). Campanian-Maastrichtian Bottom water dropped below 12C by the middle Campanian and to a minimum of 9C in the Maastrichtian in the western North Atlantic a nd low latitude SSTs were 8 to 10C cooler than modern values of ~16C (Huber et al., 2002). Th e Maastrichtian is characterized by a general cooling trend and major eustatic regressions which probably resulted in changes in deep water circulation (Haq et al., 1988). This global coolin g triggered an extinction event prior to the K/T boundary, increased latitudinal thermal gradients and increase ventilation of the deep ocean (MacLeod and Huber, 1996; Frank and Arthur, 1999; Frank et al., 2005). Intermediate and deep cool water masses were forming in high latitude s Southern Ocean, in the North Pacific and potentially in the North Atlantic (MacLeod a nd Huber, 1996; Poulsen et al., 2001, Bererra and Sarvin, 1999; Friedrich et al., 2004; Frank et al., 2005; IsazaLondono et al., 2006). MacLeod et al. (2005) proposed that intensification of the North Atlantic polar front reduced oceanic and atmospheric heat transport into the Arctic, le ading to Arctic cooling and reinforcing North Atlantic downwelling. During the last 3 Ma of the Maastrichtian intermediate and surface waters temperatures increased between 2 to 6C (Ber erra and Sarvin, 1999; Isaza-Londono et al., 2006).

PAGE 26

26 This warming may be the result of heat imported from the South Atlantic as a surface current in order to replace the sinking water in the North Atlantic (Isaza-Londono et al., 2006). Oceanic Anoxic Events The Late Cretaceou s also included major perturbations of the global carbon cycle during a series of oceanic anoxic events (OAEs) characterized by widespread deposition of organiccarbon rich marine sediments with positive or negative 13C excursions (e.g., Schlanger and Jenkyns., 1976; Arthur et al., 1990). These events represent relatively brief periods of time (Sageman et al., 2006) and must have been caused by large scale changes to the ocean environment and chemistry. At least six events have been described (OAE 1a-d, OAE 2, and OAE 3), two of which (the Selli event/OAE 1a and the Bonarelli event/OAE 2) are global (Figure 2-1). OAEs are lithostratigraphically de fined by the deposition of laminated carbon-rich sediments in environments ranging from deep ocean to shelf seas and typically chemostratigraphically defined by positive stable carbon isotope excursions. Organic carbon is depleted in 13C relative to inorganic carbon. Thus, enhan ced burial of organic carbon results in an increase in 13C in inorganic carbon, as well as sequestra tion of atmospheric carbon (Arthur et al., 1988; Kuypers et al., 1999). La te Cretaceous OAEs also coincide with short-term Sr isotope excursions to lower 87Sr/86Sr associated with the formati on of LIPs (Jones and Jenkyns, 2001). Major OAEs are believed to create a negative feedback to greenhouse conditions, such that burial of organic carbon could lead to CO2 sequestration and global co oling (Arthur et al., 1988; Jenkyns et al., 1994). Ocean Anoxic Event 2 The CTBI is associated with OAE 2, also known as the Bonarelli Event (S chlanger et al, 1987). OAE 2 represents an extreme interval of organic carbon burial. Evidence for deep sea anoxia at that time includes the high organic car bon content and laminate d sediments that were

PAGE 27

27 worldwide deposited in a range of marine se tting, including shallow shelf and deep sea environments. The distribution of green sulfur bacteria, which are oblig ate anaerobic autotrophs, during OAE 2 indicates that anoxi c condition extended into the pho tic zone for at least short intervals of time in the North Atlantic (Kuype rs et al., 2004). The CTBI is stratigraphically defined by a positive 13C excursion up to 6 in organic car bon (Erbacher et al., 2005; Forster et al., 2007; MacLeod, Unpublished data) and up to 2 in car bonate carbon (Huber et al., 1999; Gustafsson et al., 2003). At the ti me of the carbon excursion a dram atic change in the planktic foraminifer assemblage occurred with the exti nction of many deeper dwelling foraminifera and radiolarians (Rotalipora spp., Globigerinelloites bentonensis) (H uber et al., 1999). OAE 2 black shales have been described from numerous outcrops and deep-sea cores around the world, which makes the CTBI well-suited for micropaleontol ogical and chemostratigraphical correlation between cores (Arthur et al., 1988; Paul et al, 1999; Kuypers et al., 2002; Gustafsson et al., 2003; Erbacher et al., 2005, Sageman et al., 2006; Hardas and Matterlo se, 2006; Forster et al., 2007). The mechanisms for the formation of OAE 2 have been widely debated with interpretations ranging from a top down model relying on enhan ced surface productivit y, to a bottom up model that relies on anoxic deep waters. In the top down model, enhanced surface productivity due to increasing upwelling and/or terrestrial nutrient input leads to bottom water an oxia through the decay of organic matter in the deep ocean (Erbacher et al., 2004). Proposed acce leration of the hydrological cycle could have increased continental runoff of nutrients (Calvert and Peders on, 1990; Erbacher and Thurow, 1997). Another mechanism that can lead to anoxia by the top down model is the eruption of the Caribbean LIP and high oceanic crustal producti on rates. Sinton and Duncan (1997) proposed that increased hydrothermal activity associated with this volcani sm could have introduced large

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28 quantities of CO2, SO2, H2S, halogens and trace metals into the oceans, potentially stimulating primary surface production by releasi ng Fe in the form of dissolved metals into surface water. This hypothesis is supported by high abundances of trace metals that were found in marls and organic-rich sediments in the southern WIS corresponding with the onset of the 13C peak (Orth el al., 1993; Snow et al., 2005). Th e strongest signals are found in the south central and southern region of the WIS, but decrease gradually to the east and west. The enhanced organic rain rate fueled by biolimiting metals could have exceeded the capacity of the deep ocean to oxidize organic material, leading to anoxia in the wa ter column, extinction of some bottom dwelling organisms and deposition of the black shales. Ox idation of the sulfides and reduced metals released by hydrothermal effluents would have also consumed dissolved oxygen from seawater. Volcanic eruptions at that time produced at least 1000 times more material than ridge volcanism today and estimates are that oxida tion of this material would have consumed about 6% of the seawater oxygen (Sinton et Duncan, 1997). In the bottom up model, enhan ced preservation of the orga nic matter and anoxia in the deep sea is caused by decreased dissolved oxyge n in oceans and reduced oxidizing capacity of bottom water. Specifically, deep water anoxia co uld be generated by warmer intermediate and deep waters and more stagnant conditions created by decreased bottom water ventilation due to morphological barriers, density stratification, or reduced latitudinal SST gradients (Schlanger and Jenkyns., 1976). Mid-Cenomanian Event Two m illion years prior to OAE 2, a smaller prec ursor event occurred, which is referred to as the Mid Cenomanian Event (MCE) (Coccioni and Galeotti, 2003). This event is associated with large-scale changes in oceanic structure a nd climate prior to the Bonarelli event (Coccioni and Galeotti, 2003). Black shale deposition during the MCE was not as widespread as during

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29 OAE 2, but organic-rich facies can be found in th e North Atlantic, (Demerara Rise-Moriya et al., 2007; MacLeod et al., unpublished) and Tethys (Jenkyns, 1994; Coccioni and Galeotti, 2003). The MCE is also associated with a ~4 positive shift in 13Corg (MacLeod et al., unpublished) a reorganization of planktonic a nd benthic foraminiferal assemblages and a positive shift in the Sr/Ca ratio of carbonates due to changes in calcareous nannofossil productivity (Stoll and Schrag, 2001). The oxygen isotopic record indicates that the wa rming trend started with the MCE before reaching its maximum during OAE 2 (Coccioni and Galeotti, 2003). Unlike OAE 2, MCE occurred during a major sea level regressi on. Modifications of planktonic and benthic foraminifera assemblages indicate a weakening of the thermocline and an increase of water mixing (Premoli Silva and Sliter, 1999), expansi on of warm water into high latitudes, and a decrease in bottom water oxygen leve ls (Coccioni and Galeotti, 2003). Description of Sample Sites Demerara Rise Transect Sites 1258, 1260 and 1261 were drilled on De merara Rise during the Oceanic Drilling Program (ODP) Leg 207 (Shipboard Scientific Part y, 2004 a, b, c). These sites are located ~5N latitude off Suriname and French Guyana in S outh America (Figures 2-4 and 2-5) forming a SENW paleoceanographic depth transect on Demerara Rise that slopes gently to the northwest (Figure 2-6). During the Late Cretaceous, these site s were at upper to mid-bathyal depths (200 m to 1500 m) (MacLeod, personal communication). Cenomanian-Santonian black shales are separated from Campanian to Oligocene pelagic and hemipelagic chalks and marls by a hiatus representing ~7.5 My (Figure 2-7) (Erbacher et al., 2004 and 2005). OAE 2 is clearly defined at all three sites by increases in total organic carbon and 6 increases in 13C (Erbacher et al., 2005). In addition, Site 1260 includes the Mid Cenomanian Event (MCE) based on 13C patterns

PAGE 30

30 (MacLeod, personal communication). Fish teeth and debris are abundant throughout the studied interval. ODP Site 1258, the deepest site of the depth tran sect, is located at a modern water depth of 3192 m meters below sea level (mbsl). Samples we re collected from 67 to 477.49 mcd in cores A and B, spanning lithologic secti ons Units II to IV and representi ng an age range from the ~100 to 50 Ma. Site 1260 is located at a modern water de pth of 2549 mbsl. Samples were collected from 341.95 to 502.62 mcd in cores A and B, spanning lithologic Units III to V and representing an age range of 66-100 Ma. Finally, Site 1261, the shallo west site of the transect, is located at a water depth of 1899 mbsl. Samples were collected from 546.29 to 647.69 mcd, spanning lithologic Units III to IV and representing an age range of 70-96 Ma. A hiatus that corresponds to the absence of the lower Santonian-Campanian se diments is present at the three sites with slightly different durations at each site. Lithologic units are similar at all three sites (Figure 2-7): Unit V, the oldest unit recovered (early Albian; 486.28 to 510.05 mcd at Site 1260 and 480.8 to 483.5 mcd at Site 1258) is dominated by clayey limestone with quartz and calcareous claystone with quartz and high organic matter content. Unit IV ranges from 415 to 480.85 mcd (late Albian to Turonian) at Site 1258, from 393 to 486.71 mcd (Cenomanian to Coni acian) at Site 1260 and from ~564.5 to 649.73 mcd (late Cenomanian to Santonian) at Site 1261. It is primarily composed of laminated calcareous organic-rich black shale with interlay ered laminated chalk/limestone. Color variations between these two sediment types correspond to the carbonate content, which ranges from 5-95 weight percent (wt%). OAE 2 occurs within this unit, as defined by 13C (Erbacher et al., 2005). Sediment accumulation in the previous two un its occurred at 3 m/m.y. at Site 1258 and 8.5 m/m.y. at Sites 1260 and 1261. Unit III ranges from 343.46 to 415 mcd (Campanian) at Site

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31 1258, from 275.97 to 393 mcd (late Paleocene to ear ly Campanian) at Site 1260 and from 534.6 to 564.5 mcd (late Paleocenelate Campanian) at Site 1261. It is composed dominantly of nannofossil chalk with clay and claystone with an average of ~20-65 wt% carbonate content. Sediment accumulation in Unit III occurred at 10-15 m/m.y. at Site 1258, 4-12 m/m.y. at Site 1260 and 3-7 m/m.y. at Site 1261. Unit II was only sampled at Site 1258 where it spans from 8.52 to 343.47 mcd (Eocene to Maastrichtian) and consists of nannofossil and calcareous chalk with foraminifers with 30 to 80 % carbonate. Sediment accumulation in this unit occurred at 15 m/m.y. at Site 1258, 20 m/m.y. at Site 1260 and 79 m/m.y. at Site 1261(Erbacher et al., 2004). Blake Nose Transect The Blake Nose sites rep resent another depth tr ansect off Florida in the western Atlantic (Figures 2-4, 2-5, 2-8 and 2-9). ODP Site s 1049, 1050 and 1052 (Leg 171) range from ~1000 m to ~2700 m modern water depth with estimat es for paleodepth ranging from 500 to 1500 m (Huber et al., 2002; Petrizzio et al., 2008). Sedimentary stru ctures and microfossils are remarkably well preserved. Site 1050 has an in complete record of OAE 2, whereas Sites 1049 and 1052 do not contain any record s of OAE 2 (Norris et al., 1998; Huber et al., 1999). Sites 1050 and 1052 both contain OAE 1d black shales, a nd Site 1049 contains OAE 1b. The deepest site, Site 1049, is located at a modern water depth of 2671 mbsl. Sedime nts were deposited at ~1500 m water depth in the Late Cretaceous. Sa mples were collected from 134-173 mbsf for Hole A spanning lithologic Units III to IV a nd from 140 to 154 mbsl for Hole C from lithologic unit IV. The samples represent an age range of 49-115 Ma. Unit IV (middle Albian to Aptian) spans from 144.1 to 190.9 mbsf in Hole A and from 132.4 to 153.3 mbsf in Hole C. It is composed of clayey nannofossil chalk to clay ranging from 20 to 90% carbonate and an organicrich black shale representing OAE1b (Norris et al., 1998; Erbacher et al., 2001). The sedimentation rate across this unit is ~6 m/m.y. These sediments are separated from Campanian

PAGE 32

32 to early Paleocene sediments of Unit III by a hi atus representing ~28 My. Unit III (early Paleocene to Campanian) spans from 105.3 to 144.3 mbsf in Hole A and is composed of nannofossils chalk with foraminifera and cla y, and a spherule laye r representing the K/T boundary. Sediment accumulation during this interval of time was ~3.6 m/m.y. Site 1050 is located at a water depth of 2300 mbsl. Samples were collected from 174 to 313 mbsf for Hole A from litholog ic Units IC to II and from 329 to 605 mbsf for Hole C spanning from lithologic Units III to VI. The samples represent an age range of 53-102 Ma. Unit IC (late early Eocene to middle Eocene) is com posed of siliceous nannof ossil ooze to nannofossil chalk with siliceous microfossils. Unit VI (l ate Albian to late Ce nomanian) consists of nannofossil chalk or limestone with variable amounts of clay and claystone with variable amounts of nannofossils (N orris et al., 1998). The sedimentation rate across this unit is ~6m/m.y. 10 m/m.y. Unit V (late Turonian to late Campan ian) spans from 491.4 to 501.7 mbsf in Hole C and includes a series of hardgrounds from redde ned, weakly biotubated chalk to hard, heavily bored phosphate iron crust. These hardgrounds mark a distinct change in sedimentation style from the late Cenomanian to the late Campania n. The oldest hardground represents the CTBI but only the beginning of OAE 2 was recovered, as defined by a positive 13C shift (Huber et al., 1999). The sediment accumulation rate for this in terval is <1.5 m/m.y. A hiatus of ~15 My separates Units IV and V. Unit IV (Campanian to Paleocene) spans from 343.5 to 491.4 mbsf in Hole C and is composed of calcareous claystone with nannofossils to nannofossil chalk and limestone and includes the K/T boundary. Sediment accumulation during this interval of time was ~17 m/m.y.The underlying unit, Unit III (early Paleocene) spans from 327.1 to 343.5 mbsf in Hole C and contains clayey siliceous chalk with nannofossils and chert. The contact between Units II and III was not recovered. Unit II (ear ly to late Paleocene) spans from 304.9 to 319.9

PAGE 33

33 mbsf in Hole A and is made of diatomaceous nannofossil chalk and nannofossil diatiomite. The sedimentation rate across the la st two units is ~15.2 m/m.y. Site 1052 is the shallowest site of the Blake Nose depth transect. It is located at a modern water depth of 1345 mbsl. Samples were collected from 37 to 88 mbsf for Hole B from lithologic Units IC and from 140 to 677 mbsf for Hole E sp anning lithologic Units II to V. The samples represent an age range of 36-104 Ma. Unit V (Cen omanian to late Albian) spans from 343.5 to 491.4 mbsf in Hole 477.4 to 684.8 mbsf and contains dark olive silty claystone, black shale, and medium to coarse, moderately wellto well-so rted sandstone with 20 to 90 % carbonate. The OAE 2 is missing at this site. A hiatus of ~15 My separates Units IV and V. Sediment accumulation during this interval of time occurre d at ~26.2 m/m.y. Unit IV (Maastrichtian) spans from 301.6 to 477.4 mbsf and is composed of clayey nannofossil chalk with 60 to 90 % carbonate. The upper contact of the unit is the K/T boundary and the lower contact is the base of the slump that separates Maastrichtian chalk from Cenomanian limestone with interbedded siltstone of Unit V. Unit III ( early to late Paleocene) spans from 204.0 to 301.6 mbsf and contains nannofossil claystone with zeolite and nannofossil and foraminifer chalk with 20 to 80 % carbonate. Unit II (middle Eocene to late Pa leocene) spans from 140.0 to 204.0 mbsf and consists of nannofossil chalk and foraminifer chal k with chert layers a nd calcareous claystone with 20 to 80 % carbonate (Norris et al., 1998). The sedimentation rate across the last three units is ~21.7 m/m.y. Unit IC (middle Eocene) sp ans from 26.7 to 119.5 mbsf and contains nannofossil ooze to siliceous na nnofossil ooze with ~80 % carbonates. Sediment accumulation during this interval of time was ~18.2 m/m.y. Goban Spur Transect Deep Sea Drilling Project (DSDP) Sites 549, 550 and 551 (Leg 80) were drilled on Goban Spur, southwest of Ireland (Figur es 2-4 and 2-5). These sites re present a depth transect from

PAGE 34

34 bathyal to abyssal depths in the northeastern North Atlantic (Figure 2-10). Site 549, the shallowest site, is located n ear the edge of Pendragon Escarpment in 2515 meters water depth. Samples were collected from 247 to 504 mbsf, whic h represents an age range from mid Eocene to mid Albian and lithologic Units II to VI. Unit VI spans from 479 to 664.15 mbsf (Albian) and consists of gray calcareous silt stones with 20 to 80 % carbonate. The sedimentation rate in this unit is ~93 m/m.y. Unit V spans from 426.6 to 479 mbsf (early Cenomanian to early Turonian) and contains gray and greenish gray nannofossil chalk with 65 to 90 % carbonate. It includes black carbonaceous shales from 436.2 to 436.53 mbsf in which organic carbon contents range up to 3.5%. Units IV to II (Turonian to early Cenozoic) span from 198.5 to 426.6 mbsf and are composed of > 50 m of light-col ored to brown nannofo ssil chalks with ~8 5-95 % carbonate in Unit IV, 35-65 % in Unit III and 75-97 % in Unit II (De Graciansky et al, 1981; De Graciansky and Bourbon, 1985). The sedimentation rate for last four units is ~3.5-5 m/m.y. for the Upper Cretaceous and ~11 m/m.y. for the Early Cenozoic. Site 550 is located on the Porcupine Abyssal Plain at 4420 mbsl. Samples were collected from 357 to 681 mbsf, spanning lith ologic sections Units III to V. The samples represent an age range of 55-108 Ma. Unit V (uppermost Albian to middle Cenomanian) is composed of alternating carbonaceous and non-carbonaceous siltstones with 40 to 75 % carbonate that were deposited above the CCD. Unit IV (Coniacian to Santonian) is made of dark claystones interbedded with turbiditic calcareous mudstone s. The carbonate content is low (0 to 10 %), which suggests that sediments were deposited below the CCD. Unit III (upper Campanian to lower Paleocene) contains marly nannofossil chalks interbedded with cal careous turbidites and mudflows with 33 to 95 % carbonates. Site 550 has several unconformities and hiatus between the middle Cenomanian to Coniacian strata and probably between the Campanian or

PAGE 35

35 Maastrichtian and the Coniacian -Santonian, but carbonate diss olution and poor microfossil preservation prevented accurate dating of this part of the section. Sedimentation rates were 13.5 m/m.y. for the late Albian-mid Cenomania n, 1 m/m.y. for the mi d Cenomanian-lower Campanian, 17.5 m/m.y. for the Campanian-Maastric htian and 6.6 m/m.y. for the Paleocene. Paleobathymetric reconstruction place the site between 2000 and 3000 mbsl for the Late Cretaceous (De Graciansky et al, 1981; Mass on et al., 1985; De Graciansky and Bourbon, 1985). Site 551, the deepest site (3909 mbsl), is lo cated at the seaward edge of Goban Spur. Paleodepths range between 1500 to 2000 mbsl fo r the Late Cretaceous (Masson et al., 1985). Samples were collected from 107 to 143 mbsf spanning lithologic Units III to VI and representing an age range from the Cenomania n to Maastrichtian. Unit VI (late Cenomanian) spans from 138.5 to 142.4 mbsf and contains light -colored nannofossil chalk with 90 to 95 % carbonate. The contact between Units V and VI was not recovered. Unit V (early Turonian) occurs from 134.6 to 138.5 mbsf and consists of black shale mixed with gray and white chalks with 8 to 11 % carbonate. This unit represents the end of OAE 2, which has been defined by 13C by Gustafsson et al. (2003). Un it IV (Turonian) ranges from 132.5 to 134.6 and contains white to pale green nannofossil chalk and siliceous muds tone with 50 to 70 % ar bonate. Unit III (late Campanian to early Maastrichtian) spans from 100.9 to 130.5 mbsf and consists of light gray nannofossil ooze and chalk with 86 to 93 % carbonate. Sedimenta tion rates were 1.3 m/m.y. for the late Cenomanian, 2.7 m/m.y. for the Turonia n, 7.4 m/m.y. for the Campanian-Maastrichtian and 6.6 m/m.y. for the Paleocene-Eocene. Bermuda Rise Berm uda Rise extends the Blake Nose transect to abyssal depths and represents the deeper portions of the Late Cretaceous western subtropical North Atlantic (Figures 2-4 and 2-5). Site 386 (DSDP Leg 43) is located at a modern wa ter depth of 4792 mbsl on the central Bermuda

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36 Rise, south-southeast of Bermuda and has esti mated paleodepths was below 2000-3000 mbsl in the Albian-Maastrichian (Tuckol ke and Vogt, 1979). Samples were collected from 633-819 mbsf spanning lithologic section Units V to VI and Al bian to Maastrichtian ages. Unit VI (lower Albian to upper Cenomanian) is composed of dark greenish gray and black claystone with radiolarian sand beds with 90 % carbonate. Unit V (upper Cenomanian to upper Maastrichtian) contains multicolored claystones of dominantly reddish hue and s ubsidiary calcareous beds with less than 10 % carbonate. The abundance of blac k and green clays incr eases down section and Corg-concentrations exceed 10% in the vicinity of the Cenomanian to Turonian boundary. OAE 2 is defined by a 1 increase in 13C in this Unit (MacLeod, unpublished data) (Tuckolke et al., 1979). Sedimentation rates are 16 m/m.y. for th e Albian-Cenomanian an d 2.5 m/m.y. for the Turonian-Paleocene (Tucholke et al., 1979). Cape Verde Site 367 (D SDP Leg 41) is located at the base of the continental rise at 4748 meters in the Cape Verde Basin (Figures 2-4, 2-5and 2-11). It re presents an abyssal site in tropical latitudes with a paleodepth of ~3700 mbsl (Kuypers et al., 2002). It is located on the eastern side of the Mid-Atlantic Ridge, but was proximal to the Late Cretaceous tropical Atlantic gateway and to organic-rich sequences on the African margin th at are similar to the black shales on Demerara Rise (Erbacher et al., 2004). Samples were collected from 617-695 mbsf spanning from lithologic section Units III to IV a. The samples represent an age range of ~70-101 Ma. Subunit IVa (Albian to early Turonian) is composed of blac k, carbonaceous shale with organic carbon contents from 8 to 28%. The shale becomes mo re calcareous, finely laminated, and burrowed with depth. The onset of OAE 2 is defined by ~6 shift in 13C and TOC values of 20-40% (Foster et al., 2007 and unpublished data from MacL eod). The sedimentation rate across this unit

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37 is 20 m/m.y. Unit III (Turonian to early Eocene) is composed of multicolored silty clay layers separated by sharp boundaries. Sedimentation rates are 12 m/m.y. for the Turonian and 6-7 m/m.y. for the Paleocene-Eocene (Lancelot et al., 1978).

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38 Figure 2-1. Summary of major geochemical, tectonic and sea level associated with midCretaceous oceanic anoxic events (OAEs) (from Leckie et al., 2002)

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39 Figure 2-2. Plate reconstructi on: 80 Ma (Campanian, Late Cr etaceous) (Lawver et al., 2002).

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40 Figure 2-3. Compilation of gl obal benthic foraminiferal 13C and 18O record based on data from the Late Cretaceous (from Friedrich et al., 2007).

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41 Blake Nose Goban Spur Bermuda Rise Cape Verde Demerara Rise Figure 2-4. Present-day locations of ODP and DSDP study sites ( http://www-odp.tamu.edu). Figure 2-5. Paleogeographic m ap indicating the es timated location of the study sites in a plate tectonic reconstruction gene rated for the CTBI (map fr om Kuypers et al., 2002). represents shallow ODP Sites, represents intermediate ODP Sites and represents deep ODP Sites.

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42 Figure 2-6. Location of ODP Le g 207 sites on Demerara Rise with modern bathymetry (Modified from Erbacher et al., 2004). Figure 2-7. Schematic illustration of the stratigr aphic range of the Late Cretaceous sedimentary succession and major breaks in sedimentation of Sites 1258, 1260 and 1261 (from Hardas and Mutterlose, 2006).

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43 Figure 2-8. Location of the ODP Leg 171B drilling transect on Blake Nose (from http://wwwodp.tam u.edu ) Figure 2-9. Schematic interpretation of seismo logic section for Blake Nose, Leg 171B (from http://www-odp.tamu.edu ).

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44 Figure 2-10. Schematic geologic section across Goban Spur showi ng the sites drilled during Leg 80 (from http://www-odp.tamu.edu ). Figure 2-11. Location of Site 367, DSDP Leg 41 (from http://www-odp.tamu.edu )

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45 CHAPTER 3 MATERIALS AND METHODS Samples Preparation Fossil Fish Teeth and Debris Preparation Sedim ents obtained from the Oceanic Drilling Program (ODP) were wet sieved into three fractions: <63 m, 63-125 m and >125 m. Phos phatic fossil fish teeth and debris were handpicked from the >125 m fraction. Blair (20 06) demonstrated that Nd leached from the oxide fraction of bulk sediment produced the same isotopic ratio as cleaned teeth, therefore the samples were not reductively cleaned to remove the oxide coatings. Neodymium concentrations in the teeth range from 100 to 400 ppm (Martin and Haley, 2000), thus, 100 to 200 g of teeth and debris were dissolved in ~200 l of aqua regia (equal parts of 16 N HNO3 + 12 N HCl), which removed organic material. A minimum of ~3 ng Nd can be analyzed on the MC-ICP-MS. One ml of 2N HNO3 was added to each beaker of dissolved and dried fish teeth which was then capped and left to sit overnight to ensure complete dissolution. The following day, a new beaker was tared and 50 l of solution from the first beak er was placed in the tared beaker. The weight of the 50 l of solution was recorded in order to calculate the dilution factor. Both beakers were dried down. The first was re-disso lved in ~150 l of 1.6 N HCl in preparation for a two step cation exchange column process to isolate Sr and REE, and then Nd. The second, smaller sample was dissolved in 1 ml of 5% HNO3 with ~8ppb Rh + Re spike and left tightly capped overnight on a hotplate in preparation for REE analyses. Ferromanganese Oxide Coating Preparation Sa mples that did not contain e nough fossil fish teeth and debris for analyzes were instead processed to extract Nd from Fe-Mn oxide coatings in the >63 m fraction using a procedure from Blair (2006) modified from Rutberg et al. (2000). First, ~0.5 g of ground bulk sediment

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46 were dissolved in 20 ml of buffered 2.7% acetic acid in a 50 ml centrifuge tube in order to remove carbonates. The samples remained uncap ped in the hood over night and then were capped and agitated on the electr ic shaker until there was no mo re reaction. Then, the samples were centrifuged and the initial 20 ml of acid were removed. Another 20 ml of buffered acetic acid was then added to the samples and the process was repeated until there was no more reaction. The samples were then ri nsed three times with MQ grade de-ionized water. Ten ml of 0.02M Hydroxylamine Hydroxide (HH) in 25% glacial acetic was added to the residue to reduce oxide coatings in the remaining bulk sample. The sediment and HH were mixed in centrifuge tubes, shaken for 75 to 90 minutes, and then centr ifuged to isolate the leachate. The supernatant was decanted into clean 50 ml centrifuge tubes, centrifuged again, and then separated equally into two Teflon beakers. The sedi ment residues were set aside for further analyses. In order to remove any floating particles in the first cut, the solution was then transferred into small centrifuge tubes, centrifuged for ~10 minutes a nd the liquid was pipetted in the Teflon beaker. To maximize the yield, 500 l of MQ grade de-ioni zed water was added to the centrifuge tubes, centrifuged for another ~10 minutes and that liquid was added to the beaker as well. This process was repeated one more time and the samples were then dried down and re-dissolved in ~150 l of 1.6 N HCl in preparation for two sequential cation exchange columns. One split of the bulk sediment extraction (5 ml) was used for REE analyses or major element analyses. Beakers were weighed before the aliquots were transferred into them and then the samples were dried down. The beakers containing the samples were then re-weighed to calculate the sample weight, which range from ~0.001 to 0.1g. A dilution factor was then calculated in order to dete rmine the amount of 5% HNO3 with ~8ppb Rh + Re spike to add to each sample. Dilution of ~2000 times was applied to obtain optimum concentration for analyses

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47 and reduce the matrix effect. The exact source of Nd extracted by the process is unclear. Although the procedure is designed to liberate Nd from oxides, it may dissolve other phases, such as phosphate, as well. For simplicity, this fr action will be referred to as the Fe-Mn oxide fraction throughout the thesis. Silicate Residues Preparation To ensure that the carbonate and Fn-Mn oxi de fractions were com pletely removed, an additional 10 ml of HH was added to the sedi ment residues in the centrifuge tubes. These samples were capped and set in the hood for 24 hours. The sample was centrifuged and the HH was removed followed by a rinse in MQ grade de-i onized water. Next, 10 ml of 2 N HCl was added to the residue for 24 hours, centrifuged and decanted and the residue was rinsed with MQ grade de-ionized water. Next, 10 ml of 2N HNO3 was added to the sediment residue for 24 hours, centrifuged and decanted, and the residue was rinsed with MQ grade de-ionized water. Finally, 5 ml of 30% hydroxide peroxide (H2O2) was added to the residues fo r another 24 hours in order to remove the organic material which was abundant in samples during OAE 2. The residues were then rinsed with water, dried down and weighed. About 0.4 g of residue was dissolved in 1.5 ml of hydrofluoric acid (HF) and 3 ml of HNO3 of in a Teflon beaker. Tightly capped samples were left on the hotplate for ~24 hours. Once everythi ng was dissolved, the samples were split in two halves and dried down in preparation for column chemistry and REE analyses. Columns Chemistry A two step colum n process was used to isolate Sr and Nd from the fish teeth/debris and FeMn oxide fractions. Primary columns were used to separate Sr and bulk REE using Mitsubishi cation exchange resin with HCl as the eluent. Strontium was eluted using 1.6N HCl, Ba was eluted first using 2.5N HNO3 and finally bulk REEs were el uted using 4.5N HCl. The bulk REE cut was dried down, re-dissolved in 200 l of 0.18N HCl, and then loaded onto the second

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48 column. Neodymium was separated from bulk REE in a quartz column packed with Teflon beads with bis ethylhexyl phosphoric acid. The Nd wa s eluted using 0.18 N HCl and the samples were then dried down. The procedural blank is ~1.4 pg Nd. Another faster, single column technique was employed for some of the later fish teeth/debris samples that did no t required Sr analyses. Small Teflon columns were packed with Ln spec resin and Nd was isolated in a single column using 0.25N HCl as the eluent (Scher et al., submitted). For both types of columns, the Nd fraction was dried down in prep aration for isotopic analyses. The silicate residues were passed through a pr imary cation column packed with Biorad AG50W-X12 resin in order to remove Rb from th e Sr cut. Strontium was eluted first using 3.5 N HCl and then bulk REEs were eluted using 6 N HCl. The REE cut was then processed using quartz REE columns and Teflon beads as describe d above. The Sr cut was dried down, dissolved in 3.5 N HNO3 and loaded onto cation exchange columns packed with strontium-selective crown ether resin (Sr spec). Strontium was eluted usi ng 1.5 ml of 4xH2O following procedure by Pin and Bassin (1992). Neodymium Analysis Nd isotopes were analyzed using a N u Plasma Multi-Collect or-Inductively Coupled Plasma-Mass Spectrometer (MC-ICP-MS) at the Un iversity of Florida. The samples were redissolved in 0.3 ml of 2% optima HNO3 then 10l was pipetted out and placed in a sampling beaker and diluted with 0.99 ml of 2% optima HNO3. The samples were then ready to be scanned on the MC-ICP-MS. The ideal voltage ra nge for the MC-ICP-MS is between 2-6 volts for 143Nd. Hence, sample dilutions were adjusted based on this range. JNdi-1 standard was run every 6 samples to obtain a daily average for th e standard. This average was compared to the long-term running average of the JNdi-1 standard from the TIMS (Micromass Sector 54 Thermal Ionization Mass Spectrome ter) of ~0.512103 ( 0.000012, 2 ) in order to determine a correction

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49 factor for all samples run on that day. The long term error for the Nd MC-ISP-MS is determined by comparing the corrected JNdi-1 values. The calculated 2 error varies on a daily basis, but the long-term 2 error is ~0.3 Nd units. Strontium Analysis Once Sr was isolated, 87Sr/86Sr isotopic values of the samples were analyzed on the MCICP-MS using the time-resolved analysis method of Kamenov et al. (2007). The samples were dissolved with 0.3 ml of 2% optima HNO3 then 10l was pipetted out and placed in a sampling beaker and diluted with 0.99 ml of 2% optima HNO3, then the sample was scanned. On-peak zero were determined before each sample in troduction in order to correct for isobaric interferences caused by impurities of Kr in the Ar carrier gas. The ideal voltage range for the MC-ICP-MS is between 2-6 volts and sample dilutions were adju sted based on this range. NBS 987 was run every 6 samples to obtain a daily av erage for the standard, which was corrected to the long-term running average of NBS 987 which is ~0.710246 (2 = 0.000030). Sample values analyzed on a given day were corrected by the sa me amount. This ratio is similar to the longterm TIMS NBS 987 results (0.710240; 2 = 0.000023) therefore no further correction was needed. Rare Earth Elements Analyses of Fossil Fish Teeth and Fe-Mn Oxide Coatings REE analyses were obtained using the Elem ent 2 ICP-MS at UF. The analyses were perform ed in medium resolution with Re and Rh us ed as internal standards. Quantification of the results was done by external calibration using a se t of prepared REE standards. These analyses were done on a few samples from each site in or der to calculate Sm and Nd concentrations for 147Sm/144Nd corrections and to obtain REE patterns fo r fish teeth and oxide samples. Measured 147Sm/144Nd ratios for fish teeth ranged from 0.116 to 0.147 while ratios for extracted Fe-Mn oxide ranged from 0.125 to 0.156 (Table 3-1). Average 147Sm/144Nd ratios for each region were

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50 used to calculate Nd(t), which corrects for age-dependent ingrowth of radiogenic Nd. This correction ranged from 0.2 to 0.9 Nd units. Ferromanganese USGS nodule standards, N od-A and Nod-P (Flanagan and Gottfried, 1980) were analyzed for comparison with Fe-Mn oxide coating samples. The REEs obtained for each samples were normalized to PAAS (Post-Ar chean Australian Shale) (Taylor and McLellen, 1985). REE measurements have an error of 5% and the blan k is negligible. Major Elements Analyses of Fe-Mn Oxide Coatings Concentrations of Al, Ca, Fe, Mg, Ti, Mn, Si and Ti were analyzed on Fe-Mn oxide coatings samples and on Nod-A and Nod-P using the Elem ent 2 ICP-MS. The nodule samples were prepared using 0.05 g of Nod-A and Nod-P w ith two drops of de-ion ized water, 5 ml of HNO3, 0.3 ml of HCl and 0.1 ml of HF (Axelsson et al., 2002). Ferromanganese oxide samples were diluted with 5% HNO3 spiked with ~8ppb Rh + Re spike, equivalent to ~15000 times dilution to achieve suitable concentrations fo r major element measurements on the ICP-MS. Quantification of the results was done by external calibration to a set of prepared standards containing the elements of interest. The error for major elements analyses is 5% and the blank is negligible.

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51 Table 3-1. Average of 147Sm/144Nd measured at the different sites. Site 147Sm/144Nd Fish Teeth Fe-Mn Oxide coatings Residual fraction 367 0.130 0.138 386 0.147 0.147 549 0.134 N/A 550 N/A 0.162 551 N/A N/A 1049 N/A 0.138 1050 0.116 0.157 1052 0.127 0.138 1258 0.125 0.127 1260 0.125 0.125 0.097 1261 0.125 N/A

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52 CHAPTER 4 RESULTS Neodym ium isotopes of fossil fi sh teeth/debris and Fe-Mn ox ide coatings were analyzed from three depth transects in northern to the equa torial North Atlantic Ocean basin: Blake Nose, Demerara Rise and Goban Spur, and two deep site s, Bermuda Rise and Cape Verde. The aim of the study was to determine the temporal and spatial Nd patterns across the North Atlantic in the Late Cretaceous, and particularly across OAE 2. Thus, the distribu tion of the water masses in the North Atlantic was constrained for upper bath yal to abyssal depths with higher sampling resolution across OAE 2. Neodymium Results Demerara Rise Transect Overall, Nd values at Demerara Rise in the La te Cretaceous are very non-radiogenic except during the OAE 2 and MCE. Table 4-1 lists Nd(0) and Nd(t) values from each site. All three sites record similar variations in Nd(t) during the Cretaceous. At Site 1258 Nd(t) in the oldest part of the record ranges from .4 to 16.4 from 426.04 to 480.29 mcd (Figure 4-1). These values increase rapidly at 425.84 mcd, shifting to more radiogenic values ranging from -7.4 to 13.2 then decrease back to pr e-shift values of ~-16 from 422.14 to 309.87 mcd. Starting at 308.29 mcd Nd values increase to -11.4 and remain close to this value until 67.28 mcd. In the oldest part of the record at Site 1260 (Figure 4-2) Nd(t) values range from .0 to -16.1 from 502.62 to 426.66 mcd with typical values of ~14 within this inte rval. From 453.52 to 444.57 mcd, there are two peaks in Nd(t) which range up to -11.1. A more distinct peak occurs between 426.41 to 424.81 mcd when Nd(t) values rapidly shift to more radiogenic values ranging from -9.5 to -12.9. After 424.81 mcd Nd(t) decrease to values of -13.8 to -17.8. At Site 1261 (Figure 4-3)

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53 Nd(t) values range from -13.8 to -15.6 from 647.7 to 637.68 mcd, and then increase to -8.5 to 13.8 from 637.0 to 629.76 mcd, before returnin g to -13.1 to -16.6 from 629.29 to 546.29 mcd. Figures 4-4, 4-5 and 4-6 illustrate Nd(t) values versus time for all three sites at three different scales. Neodymium values before and af ter OAE 2 are ~-14 to -16 at all three sites (Figure 4-4). At Site 1260, the higher peak (-11.1 ) of the two peaks preceding OAE 2 correlates with the MCE at ~96 Ma from 449.07 to 446.79 mcd as defined by 13C (Figure 4-7). The more dramatic Nd isotopic excursion of ~8 Nd units recorded at all the sites from 94.08 to 93.53 Ma coincides with OAE 2 (Figures 4-7 and 4-8), as defined by 13C (Erbacher et al., 2005). A hiatus occurs in all three sites from ~79 to 88 Ma, al though the duration varies slightly between sites (Figure 4-4). In the late Masstrichtian, Nd(t) values at Site 1258 increase to ~-13 and then reach 11 in the Paleocene. For all three sites, Nd(t) values increase very rapidly at the beginning at ~94.08 to 94.03 Ma (Figure 4-6). Figure 4-8 highlig hts the correlation between Nd(t) and 13C during OAE 2 Demerara Rise sites. Maximum peak Nd(t) values during OAE 2 are -7.4 at Site 1258, -9.5 at Site 1260 and -8.5 at Site 1261 (Figures 4-6 and 4-8). Neodymium isotopic values have an early peak at the onset of the ev ent of -7.4 at Site 1258, -9.6 at Site 1260, and -11.0 at Site 1261, then drop to lower values ranging from -12.2 to -13.8, followed by a second, more extended Nd peak with Nd values of .4 for Site 1258, .4 for Site 1260, and .5 for Site 1261 (Figures 4-6 and 4-8). In comparison, 13C values remain on more of a plateau throughout OAE 2 with each site recording slightly different variability. The reco very phase at the end of the event is a more continuous decline. Extractions of Nd from disp ersed Fe-Mn oxide coatings a bove, within and below the excursion at Site 1258 yield isotopic ratios that are consistent with data from fish teeth apatite

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54 (Blair, 2006) (Table 4-2 and Figure 4-9). In addition, REE patterns from the Fe-Mn oxides before, during and after the OAE 2 and for two USGS Fe-Mn standards (F lanagan and Gottfried, 1980) all reveal slight middle REE enrichments when normalized to PAAS (Figure 4-10). This pattern is typical for the Fe-M n oxide fraction (Bayon et al., 2002; Haley et al., 2004; Gutjahr et al., 2007). Blake Nose Transect Table 4-3 lists the Nd(0) and Nd(t) values from fish teeth and/or Fe-Mn oxide coatings from Sites 1049, 1050 and 1052 on Blake Nose. At Site 1049 th e oldest part of the record from 157 to 128 mcd has radiogenic Nd(t) values ranging from -4.8 to -6.6. The youngest part of the record has values ranging from -7.6 to -9.6 between 131.2 and 58 mcd, with a hiatus of >10 m.y. separating the two sections. At Site 1050 the general pattern is similar to Site 1049 with more radiogenic values of -4.4 to -5.9 in the older part of the record (605 to 495 mcd) and a shift towards less radiogenic values of -7.4 to -9.0 ac ross a hiatus in the younger part of the record (491 to 177 mcd). Site 1052 also follows the gene ral trend of Sites 1049 and 1050. The older part of the record displays Nd(t) values of -3.2 to -5.2 from 677 to 478 mcd and these values decrease to less radiogenic values of -7.4 to -9.1 from 466 to 40 mcd a hiatus. Figure 4-14 illustrates that unlike Demerara Rise sites, Nd(t) values at Blake Nose sites have distinct values at different depths for the ol der part of the section (late Aptian to Turonian). The shallowest site, Site 1052, has the most radiogenic Nd(t) values, which range from -3.2 to 5.2. The intermediate site, Site 1050, has intermediate Nd(t) values ranging from -4.4 to -5.9. Although the deepest site, Site 1049, does not fully overlap with the ages of the other sites, it records the least radiogenic valu es ranging from -4.8 to -6.6. Va lues from Site 1052 decrease toward values from 1050 in the late Cenomanian. Site 1050 is th e only site that recovered any part of OAE 2. As defined by 13C, a short segment representing an incomplete and condensed

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55 OAE 2 spans from 500.96 to 500.75 mbsf in core C (Figure 4-15) (Huber et al., 1999). The Nd peak occurs at 500.77 mbsf after the 13C peak at 500.88 mbsf. At the onset of OAE 2 Nd(t) is 5.3, then it peaks to -4.4, indicating a shift of ~1 Nd unit in the earliest part of the event. Much of the Turonian-Campanian is missing at all Blake Nose sites due to a hiatus of ~12 m.y. There is a shift to less radiog enic values after the hiatus a nd a diminished gradient between the sites (Figure 4-14). Site 1049 has Nd(t) values that range from 7.6 to -8.7 from ~72 to 56 Ma and then decrease to -9.6 for one point at ~50 Ma. At Site 1050, Nd(t) values range from -7.4 to 9.0 from ~78 to 50 Ma. Nd values at Site 1052 look similar to those at Site 1050 with Nd(t) values that range from -7.2 to -8.2 in the Maastr ichtian and late Campanian and from -8.0 to -9.2 in the Paleocene and Eocene. Neodymium isotopic values of fish teeth/de bris samples and those of extracted Fe-Mn oxide are within error for eight out of ten paired samples. In general, Nd(t) values of fish teeth/debris are slightly higher than Nd(t) values of Fe-Mn oxide samples. Goban Spur Transect Neodym ium isotopes were sampled at lower resolution for ODP Sites 549, 550 and 551 at Goban Spur for the Late Cretaceous in order to get a general idea of Nd(t) values at a depth transect from a high latitude Nort h Atlantic location (Table 4-4) Due to poor biostratigraphy and magnetostatigraphy, no age model has been developed for these sites, thus they cannot be correlated on a single graph. However, samples ha ve been divided into general ages based on low resolution biostratigraphy (Shi pboard Scientific party, 1985). Fossil fish teeth and debris were rare at Sites 549 and 550, t hus mostly Fe-Mn oxide coatings were analyzed. In contrast, fossil fish teeth and debris were abundant in the black shales common at Site 551. Albian Nd(t) values are -8.3 and -8.5 in the late Albian (503.1 to 483.6 mbsf) at Site 549 (Figure 4-16) and then vary w ithin a broader range from -7.6 to -10.5 from the Cenomanian to

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56 Santonian (455.57 to 408.05 mbsf). A Nd peak of -7.5 at 436.55 mbsf in the black shales may correspond to the OAE 2 (Shipboard Scientific party, 1985). Unfortunately, there is no 13C data for this location to verify the presence of the event. In the late Campanian and early Maastrichtian, Nd(t) decreases to less radiogenic values ranging from -9.7 to -10.6 (404.55 to 390.55 mbsf), then increases again, ranging from -7.3 to -9.5 from la te Maastrichtian to Paleocene (380.25 to 324.05 mbsf). A single data poi nt of -9.75 at 247.05 mb sf in the Eocene indicates a decreasing trend. At Site 550, Nd(t) displays a general decreasing trend from -7.1 to -10.1 at depths of 680.26 to 475.45 mbsf corresponding to the Albian to Maastrichtian (Figure 4-17). One data point at 357 mbsf suggests an increasing tre nd up to -7 in the Paleocene. At Site 551, Nd(t) values decline from -7.7 to 9.6 in the Cenomanian from 142.05 to 138.62 mbsf (Figure 4-18). Following an interval of no recovery, Nd(t) values jump to -6.8 at 135.12 mbsf just before OAE 2 as defined by the 13C shift in bulk carbonates (Gustafsson et al. 2003), indicating that only the end of OAE 2 was recovered (Figure 4-19). The highest Nd(t) reported for Site 551, -5.0 at 134.44 mbsf, occurs during the section defined as OAE 2 from 135.63 to 134.56 mbsf Due to the lack of recover y, it is impossible to determine by how much Nd(t) increases during OAE 2; however, following the peak, Nd(t) values return to ~-6.5 for the rest of the Turonian (134.12 to 133.72 mbsf). Neodymium isotopic values then decrease dramatically to -9.9 at 124.3 mbsf before increasing again to -8.3 at 107.58 mbsf in the Campanian and Maastrichtian (Figure 4-18). The va lues for this interval are comparable to Campanian-Maastrichtian values from the two other sites. Neodymium isotopic values of fish teeth/de bris samples and those of extracted Fe-Mn oxide are within error for ei ght out of ten paired sample s at Site 551. In general, Nd(t) values of

PAGE 57

57 fish teeth/debris are slightly higher than Nd(t) values of Fe-Mn oxide samples. Five pairs of fish teeth/debris and Fe-Mn oxide samp les at Sites 549 and 550 have been analyzed. Two out of five are falling within error and thr ee out of five fish teeth sample s plot higher than Fe-Mn oxide samples. For one of the sample that did not fall within error, Nd(0) values of the paired samples agreed within error. The offset may be related to the fact that Sm and Nd concentrations were only measured for few samples and thus the correction applied to obtain the Nd(t) may be off. Bermuda Rise Fossil fish teeth and Fe-Mn oxide coatings have been analyzed at ODP Site 386 on the Berm uda Rise. Again, the age model for this site is poorly developed, although 13C data (MacLeod, unpublished data) has been used to locat e the position of OAE 2. Table 4-5 lists the Nd(0) and Nd(t) values from fish teeth and/or Fe-Mn oxi de coatings for Site 386. From the late Albian to early Cenomanian Nd increases from -7.7 to -6.9 (818.54 to 804.77 mbsf) and then remains at ~-6.5 from 804.77 to 740.88 mbsf until th e onset of OAE 2 (Figure 4-20). OAE 2 is identified by a 1 13C shift in bulk carbonate (MacLeod and Jimenez Berrocoso, unpublished data) (Figure 4-21), which is similar to the 13C shift at Blake Nose and also indicates that the section is incomplete. An Nd(t) increase of ~2 Nd units coincides with the 13C shift, such that values during OAE 2 peak at -4.7 at 738.93 mbsf. This Nd excursion is twice the excursion observed at Blake Nose. From the Turonian to Santonian, Nd(t) values range from -6.8 to -7.6 from 724.29 to 692.66 mbsf and then decrease from -8.4 to -10.5 between 642.64 and 633.6 mbsf in the Campanian or Maastrichtian (Figure 4-20 ). Neodymium values of fish teeth/debris samples and those of extracted Fe-Mn oxide are within error for the tw o out of two paired samples analyzed.

PAGE 58

58 Cape Verde Neodym ium contained in both fossil fish teet h/debris and Fe-Mn oxide coatings were analyzed at ODP Site 367 off Ca pe Verde (Table 4-6 and Figure 4-22). The age model for this site is also poorly developed, but th e position of OAE 2 wa s located with the 13C shift in bulk carbonate (MacLeod and Jimenez Berrocoso, unpub lished data). In the late Albian to Cenomanian, Nd(t) ranges from -8.5 to -9.8 between 647.76 to 695 mbsf (Figure 4-22). Coring gaps extend from ~685.5 to 654.0 mbsf, from 645.7 to 644.5 mbsf and from 636.6 to 625.5 mbsf, thus only the beginning of the event was recovered. OAE 2 has been defined by ~6 shift in 13C (Forster et al., 2007; MacLeod et al., unpubli shed data) starting at 641.38 mbsf (Figure 423). No Nd isotopic data were collected fr om for the early part of OAE 2. The first Nd(t) value within OAE 2 is -8.6 at 641.49 mbsf based of fish teeth; howev er, on an Fe-Mn oxide sample from the same depth had a value of -6.5. A repl icate analysis of the Fe-Mn oxide sample was attempted, but the sample size was too small. Two Nd(t) peaks of -7.7 and -7.5 at 639.21 and 637.2 mbsf respectively correspond to shifts of ~1.5 Nd units (Figure 4-23). While 13C values are still high, Nd(t) values return to ~-9 (-8.6 for the fish tooth and -9.0 for the oxide). In the Campanian and Maastrichtian, Nd(t) values are quite variable, decreasing from -9.5 to -10.1 between 621.22 and 620.84 mbsf and then in creasing to -8.4 from 619.68 to 617.22 mbsf. Analyses of the youngest sample at 617.22 mbsf produced highly distinct values for fish teeth/debris versus Fe-Mn oxide s and the oxide replicate was too small for analyses. However, the Nd concentration of the replicate was too low for it to be analyzed on the ICP-MS. A total of 9 paired sample analyses were r un and 6 agreed within error. Rare Earth Elements Plots Individual sam ple analyses of REE extracte d from Fe-Mn oxide coatings are plotted for Sites 1049, 1050 and 1052 (Table 4-7 and Figures 424, 4-25, 4-26), while average values are

PAGE 59

59 plotted for Sites 367, 386, 550, 1049, 1050, 1052, 1258 and 1260 in order to obtain a REE pattern typical of each location (Table 4-7 a nd Figure 4-27). Additional measurements were made on uncleaned fish teeth from Sites 367, 386 and 1260 (Table 4-8 and Figures 4-28, 4-29 and 4-30). All samples have been normalized to their original weight a nd to PAAS (Taylor and McLellen, 1985) and thus reflect relative concentr ations. Fe-Mn oxides from Sites 550, 1049, 1050, 1052 and 1260 have the highest concentrations whereas the deeper sites, Sites 367, 386 and 1258, have lower concentrations of REE. High concentration s ites have a distinctive middle (M-) REE bulge. Except for Sites 386 and 550, all of the sites also have slight negative Ce anomalies. In contrast, Site 550 has a slight positive Ce anomaly, as do Nod A and Nod P. REE analyzed from fish teeth for Site s 367, 386 and 1260 have a less pronounced MREE bulges compared to coatings samples (Table 4-8) Site 367 has the lowest concentrations with more pronounced Ce anomalies compared to the two other sites (Figure 4-28). Site 386 has almost an order of magnitude higher concentrat ion than the two other sites and small or nonexistent negative Ce anomalies (Figure 4-29). Con centrations for Site 1260 are in between Sites 367 and 386 with a similar pattern to Site 386 (Figure 4-30). A few of the fish teeth samples at Site 367 and 1260 have HREE enriched pattern, similar to typical seawater pattern. Sequential Extraction Results The goal of the sequential extraction on sedim ent from Site 1260 at Demerara Rise was to determine Nd and Sr isotopic values and REE patte rns for the various fractions of a given sample including fossil fish teeth, Fe-M n oxide coatings and the residu al fraction (Table 4-9). The Nd(t) values for Fe-Mn oxide coatings fall within error of the fish teeth values for 5 out of 6 samples, and the offset is only 0.8 Nd units for the one sample outside of error (Figure 4-31). For three of the samples, Nd(t) values for the residual fractions are less radiogenic (more continental) than the two other fractions. For the one remaining sample the residue value plots within error of the

PAGE 60

60 other fractions, which may indicate that the sample preparation did not completely remove the Fe-Mn oxide coatings. In an initial experiment the residue fractions were only processed in HH for 24h and the resulting residual Nd(t) values were dominated by the seawater signal. When the samples were re-processed with two additional st eps of 2N HCl and 2N HNO3 for 24h each, the residue values decreased significantly. Strontium isotopes were also analyzed for the Fe-Mn oxide and residual fraction from each sample from Site 1260 (Table 4-9). 87Sr/86Sr ratios from Fe-Mn oxide coatings are close to seawater 87Sr/86Sr ratios (McArthur, 2001) for the same age, but tend to be slightly more radiogenic (Figure 4-32). On the other hand, 87Sr/86Sr ratios from the residual fractions are much more radiogenic than seawater and Fe-Mn oxide coating ratios, indicating that they record a more continental signature. REE were also analyzed for the Fe-Mn oxide co atings and residual fractions (Table 4-10). The PAAS-normalized REE plots for the Fe-Mn oxide coatings fraction show distinct MREE enrichment for 2 out of 6 samples (Figure 4-33). The other four have lowe r concentrations and a more seawater pattern. The residual fractions have lower concentrations and flat PAASnormalized REE patterns (Figure 4-34). Several of the samples have a positive Eu anomaly. Major Elements Ratios Major elem ents ratios were measured on a number of extracted Fe-Mn oxide coating samples in order to further check the integrity of the Fe-Mn oxide signal (Tables 4-11). REE values of analyzed Nod-A and Nod-P are sim ilar to published USGS values (Flanagan and Gottfried, 1980). Major elementa l ratios of Fe-Mn oxide coati ngs display a high variability. Major elements are compared to those of the average continental crust and USGS Fe-Mn nodule standards (Nod-A and Nod-P) to evaluate whether they are similar to weathered material or FeMn coatings. The ratios Al/Fe+M n, Ti/Fe+Mn and Si/Fe+Mn of th e continental average crust are

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61 higher by at least one order of magnitude than those of the coatings and the Fe-Mn nodule standards. Phosphate to Fe+Mn and P/Nd ratios are higher than for th e Fe-Mn nodule standards. Elemental ratios were also analyzed on fossil fish teeth (Table 4-13) and also show high variability.

PAGE 62

62 Table 4-1. Demerara Rise Nd isotopic valu es from Fossil Fish Teeth from ODP Sites 1258, 1260 and 1261. Sample Depth (mbsf) Depth (mcd) Age1 (Ma) 143/144Nd2Nd(0) 3 Nd(t) 4Error5 Site 1258 (3192 m) 1258A 8R-3W 20-26 65.4367.2850.750.512035-11.8 -11.40.2 1258A 17R-2W 20-26 150.73117.5754.450.512032-11.8 -11.40.1 1258A 25R-3W 60-66 229.63252.0857.900.512064-11.2 -10.70.1 1258A 27R-2W 100-106 247.83297.2864.100.511973-13.0 -12.50.1 1258A 31R-2W 10-19 285.55308.2966.700.511948-13.5 -12.90.1 1258A 31R-3W 20-26 287.13309.8766.800.511800-16.3 -15.80.1 *1258A 38R-1 105 375.2074.980.511804-16.3 -16.1 *1258A 42R-1 8 414.8392.430.511824-15.9 -15.0 *1258A 42R-1 66 415.4092.520.511867-15.0 -14.2 1258A 42R-2W 85-86.5 392.15417.1092.770.511847-15.4 -14.60.1 *1258A 42R-3 60 418.2492.940.511899-14.4 -13.6 *1258B 45R-1 95 419.2893.090.511724-17.8 -17.0 *1258B 45R-1 96 419.2993.090.511748-17.4 -16.5 *1258B 45R-3 36 420.5493.280.511864-15.1 -14.3 *1258B 45R-3 51 420.6993.300.511783-16.7 -15.8 *1258B 42R-5 12 421.2993.390.511841-15.5 -14.7 *1258A 42-6 2 421.5193.420.511945-13.5 -12.7 *1258A 42-6 32 421.8193.470.511846-15.4 -14.6 *1258A 42-6 60 422.0993.550.511940-13.6 -12.8 *1258A 42R-6 66 422.1493.560.512028-11.9 -11.1 *1258A 42R-6 96 422.44 93.60 0.511938 -13.7 -12.8 *1258A 42R-6 116 422.64 93.63 0.511921 -14.0 -13.2 *1258A 42R-7 7 422.96 93.67 0.511967 -13.1 -12.3 *1258A 42R-7 26 423.14 93.70 0.511978 -12.9 -12.0 1258A 42R-7W 50-51.5 398.44 423.39 93.73 0.512083 -10.8 -10.0 0.1 *1258A 42R-7 71 423.59 93.76 0.512175 -9.0 -8.2 *1258A 42R-7 93 423.81 93.79 0.512074 -11.0 -10.2 1258A 42R-7W 105-106.5 398.99 423.94 93.81 0.512204 -8.5 -7.6 0.1 1258A 42R-7W 115-116.5 399.09 424.04 93.82 0.512148 -9.6 -8.7 0.1 1258C 17X-1 5-6.5 399.45 424.84 93.93 0.511967 -13.1 -12.2 0.1 1258C 17X-1 10-11.5 399.50 424.89 93.94 0.511954 -13.3 -12.5 0.1 1258C 17X-1 40-41.5 399.80 425.19 93.98 0.512196 -8.6 -7.8 0.1 1258C 17X-1 50-51.5 399.90 425.29 93.99 0.512213 -8.3 -7.4 0.1 1258C 17X-1 75-76.5 400.15 425.54 94.03 0.512076 -11.0 -10.1 0.1

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63 Table 4-1. Continued *1258C17X1-85-86.5 425.64 94.04 0.512145 -9.6 -8.8 *1258C17X1-105-106.5 425.84 94.07 0.512120 -10.1 -9.3 *1258C17X1-125-126.5 426.0494.100.511841-15.5 -14.7 1258A 42R-7W 135-136.5 399.29426.2494.120.511860-15.2 -14.30.1 *1258C17X2-10-11.5 426.2894.130.511847-15.4 -14.6 *1258C17X2-30-31.5 426.4894.160.511805-16.2 -15.4 1258A 43R-1W 66 400.06426.9494.220.511791-16.5 -15.70.3 1258A 43R-2W 42-44 401.10426.9894.230.511831-15.7 -14.90.2 *1258C17X2-70-71.5 426.8894.280.511766-17.0 -16.2 1258A 43R-2W 124 401.92428.8094.480.511754-17.2 -16.40.3 *1258B 47R-1 23 429.3994.540.511917-14.1 -13.2 1258B 47R-2W 116-117.5 409.45431.5194.850.511851-15.4 -14.50.1 1258B 47R-3W 124-126 410.84432.9095.040.511778-16.8 -15.90.1 1258B 47R-4W 102.5-104 412.07434.1295.210.511780-16.7 -15.90.1 *1258B 48R-1 111 435.8795.220.511764-17.0 -16.2 *1258B 49R-1 45 439.2095.570.511822-15.9 -15.1 *1258B 49R-3 31 441.7395.840.511853-15.3 -14.5 1258A 45R 2W 51-53 445.3896.220.511795-16.4 -15.60.1 *1258A 45R-2 57 445.4396.220.511822-15.9 -15.1 1258A 46R 1W 22-24 448.4196.540.511780-16.7 -15.90.1 1258A 46R 1W 41-43 448.6096.560.511826-15.8 -15.00.1 1258A 46R 1W 70-72 448.8996.590.511832-15.7 -14.90.1 1258A 46R 1W 100-102 449.1996.620.511816-16.0 -15.20.1 *1258A 46R-2 68 450.2296.730.511859-15.2 -14.4 *1258A 46R-4 33 452.5396.970.511812-16.1 -15.3 *1258A 47R-1 12 456.0497.340.511873-14.9 -14.1 1258B 56R-2W 23-29 452.49477.4999.590.511959-13.2 -12.40.2 *1258C 27R-2 0 480.29100.210.511935-13.7 -12.8 Site 1260 (2549 m) 1260 A 37-4W 130-132 342.21341.9566.330.511825-15.9 -15.30.1 1260 A 38R 5W 2-4 352.03352.7768.430.511770-16.9 -16.30.1 *1260 A 39R 1W 78 357.1269.620.511788-16.6 -15.90.0 1260 B 26R 7W 10-12 366.81368.3772.700.511815-16.0 -15.50.2 *1260 A 40-1W 109 369.0572.890.511776-16.8 -16.10.0 *1260 40 3W 104-372 372.0073.690.511801-16.3 -15.60.0 *1260 A 42-2W 77 389.8978.580.511783-16.7 -16.00.0 1260 A 42-4W 2-4 389.02391.2378.410.511806-16.2 -15.50.2 1260 B 31R CCW 3-5 396.00398.2189.980.511866-15.1 -14.20.1

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64 Table 4-1. Continued 1260B 32-1W 3-5 396.14398.3590.000.511800-16.3 -15.50.2 1260 B 32R 1W 24-26 396.35398.5690.030.511741-17.5 -16.70.1 1260B 32-1W 97-99 397.08399.2990.140.511701-18.3 -17.50.1 1260B 32-2W 32-34 397.93400.1490.270.511697-18.4 -17.60.2 1260 B 32R 2W 56-58 398.17400.3890.310.511890-14.6 -13.80.1 1260B 33 1W 20-33 400.00402.2190.530.511787-16.6 -15.80.1 1260 B 33R 1W 92-94 400.70402.9190.690.511813-16.1 -15.30.1 1260B 33 2W 94-96 403.15405.3691.240.511688-18.5 -17.70.2 1260 B 35R 2W 120-121 418.00422.5492.640.511831-15.7 -14.90.1 1260B 35-3W 41-45 418.77423.3192.810.511873-14.9 -14.10.1 1260B 35-4W 52-54 420.27 424.81 93.53 0.511979 -12.9 -12.0 0.1 1260 B 35R 4W 61-63 420.37 424.91 93.55 0.511939 -13.6 -12.8 0.3 1260 B 35R 4W 70-72 420.47 425.01 93.59 0.511969 -13.0 -12.2 0.2 1260B 35-4W 80-82 420.57 425.11 93.64 0.512003 -12.4 -11.5 0.2 1260 B 35R 4W 90-92 420.67 425.21 93.66 0.512062 -11.2 -10.4 0.1 1260 B 35R 4W 103-104 420.77 425.31 93.70 0.512051 -11.4 -10.6 0.1 1260 B 35R 4W 118-120 420.92 425.46 93.76 0.512097 -10.5 -9.7 0.1 1260 B 35-5W 26-27 421.42 425.96 93.87 0.512109 -10.3 -9.5 0.2 1260 B 35R 5W 37-38 421.57 426.11 94.01 0.511949 -13.4 -12.6 0.1 1260B 35-5W 46-47 421.67 426.21 94.03 0.511932 -13.8 -12.9 0.1 1260B 35-5W 55-57 421.77 426.31 94.05 0.512100 -10.5 -9.6 0.1 1260 B 35-5W 60-62 421.87 426.41 94.08 0.512018 -12.1 -11.2 0.2 1260B 35-5W 90-92 422.12426.6694.130.511807-16.2 -15.40.1 1260B35-5-120-121 422.41426.9594.470.511792-16.5 -15.70.2 1260 B 35R 6W 20-22 422.97427.5194.510.511880-14.8 -13.90.1 1260 A 48R 4W 10-22 438.15441.7495.540.511892-14.5 -13.70.2 1260A 48-6W 30-31 440.98444.5795.740.511867-15.0 -14.20.1 1260A 49-1W 130-131 444.40 447.99 95.99 0.511965 -13.1 -12.3 0.1 1260 A 49-2W 40-41 444.93 448.52 96.03 0.512024 -12.0 -11.1 0.2 1260A 49-3W 10-12 446.05449.6496.110.511888-14.6 -13.80.1 1260 A 49-3W 80-82 446.75450.3496.160.511937-13.7 -12.80.1 1260A 49 4W 50-52 448.11451.7096.260.511937-13.7 -12.80.2 1260A 49-5W 5-7 449.00452.5996.320.511977-12.9 -12.00.1 1260A 49-5W 98-100 449.93453.5296.390.511881-14.8 -13.90.1 1260 A 51R 4W 10-11 466.60470.2597.600.511920-14.0 -13.10.1 1260 A 52-4W 130-132 483.00485.6898.710.511947-13.5 -12.60.2 1260 B 44R 1W 45-4 492.36495.0499.380.511764-17.0 -16.10.1 1260 B 45R 3W 42-45 499.94502.6299.930.511780-16.7 -15.80.1

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65 Table 4-1. Continued Site 1261 (1899 m) 1261A 39 1W 40-42 545.01546.2970.070.511799-16.4 -15.70.1 1261 A 39R CCW 23-25 553.84555.1271.200.511755-17.2 -16.60.1 1261 A 40R 3W 10-12 557.31558.5972.190.511713-18.0 -17.40.1 1261 A 41-2W 50-52 565.81567.0973.290.511796-16.4 -15.80.1 1261 A 43 1W 100-102 584.01585.2988.240.511799-16.4 -15.60.2 1261 A 43 3W 133-134 587.33588.6188.650.511763-17.1 -16.30.2 1261 A 43 5W 42-44 591.83593.1189.200.511777-16.8 -16.00.2 1261 A 44 1W 8-10 592.69594.1089.320.511826-15.8 -15.00.2 1261 A 44 3W 117-119 596.78598.1989.830.511767-17.0 -16.20.2 1261 A 44 5W 117-134 599.85601.2690.210.511756-17.2 -16.40.1 1261 A 47-2W 90-92 623.69621.5993.260.511872-14.9 -14.10.2 1261 A 47R 4W 92-94 628.33626.2393.280.511823-15.9 -15.10.2 1261 A 47R 6W 81-83 629.72627.6293.450.511837-15.6 -14.80.1 1261 A 47R 6W 131-133 630.22628.1293.460.511820-16.0 -15.10.1 1261 A 48R 1W 20-22 631.20628.2693.470.511907-14.3 -13.40.1 1261 A 48R 1W 70-72 631.71628.7793.510.511858-15.2 -14.40.1 1261 A 48 1W 122-124 632.23629.2993.540.511924-13.9 -13.10.1 1261 A 48R 2W 20-22 632.70 629.76 93.57 0.511933 -13.7 -12.9 0.2 1261 A 48R 2W 70-72 633.21 630.27 93.60 0.511954 -13.3 -12.5 0.2 1261 A 48R 2W 142-144 633.92 630.98 93.65 0.511978 -12.9 -12.0 0.1 1261A 48 3W 43-45 634.45 631.51 93.68 0.511931 -13.8 -13.0 0.1 1261 A 48R 3W 80-82 634.81 631.87 93.70 0.511938 -13.6 -12.8 0.1 1261 A 48R 3W 141-143 635.41 632.47 93.74 0.511939 -13.6 -12.8 0.1 1261 A 48R 4W 141-143 636.91 633.97 93.83 0.512159 -9.3 -8.5 0.1 1261 A 48R 5W 42-44 637.43 634.49 93.87 0.512076 -11.0 -10.1 0.1 1261A 48 5W 81-83 637.83 634.89 93.89 0.511898 -14.4 -13.6 0.1 1261 A 48R 6W 6-8 638.57 635.63 93.94 0.511896 -14.5 -13.6 0.1 1261 A 48R 6W 36-38 638.87 635.93 93.96 0.511889 -14.6 -13.8 0.1 1261 B 13-2W 11-13 637.20 635.96 93.96 0.512005 -12.3 -11.5 0.2 1261 B 13-2W 67-69 637.75 636.51 93.99 0.511909 -14.2 -13.4 0.1 1261 B 13R 2W 97-99 638.08 636.84 94.01 0.511948 -13.5 -12.6 0.1 1261 B 13-2W 116-118 638.27 637.03 94.03 0.512031 -11.8 -11.0 0.1 1261 B 13 3W 31-33 638.92637.6894.120.511800-16.3 -15.50.1 1261 A 49R 1W 127-128 641.88638.5594.800.511797-16.4 -15.60.2 1261 A 49-4W 120-122 646.27642.8495.210.511795-16.4 -15.60.3 1261 A 50R 2W 130-132 651.48647.6995.930.511886-14.7 -13.80.2 1. Ages for Sites 1258, 1260 and 1261 were calculated after Erbacher, 2004 and 2005. 2. 143/144Nd values are normalized to the JN di-1 average on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (TIMS average) 3. Nd(o) = [(143Nd/144Nd)sample/(143Nd/144Nd)CHUR-1] x 104

PAGE 66

66 4. Nd(t) = [(143Nd/144Nd)sample(t)/(143Nd/144Nd)CHUR(t)-1] x 104 using 147Sm/144Nd = 0.125 5. Listed errors indicate the w ithin run uncertainty. For all plots, a minimum error of 0.3 Nd unit is applied representing the 2 uncertainty of repeat analyses of JNdi-1. indicates samples from Blair (2006). Blue highlighting represents OAE 2 and purple highlighting represents MCE. Figure 4-1. Nd(t) values from fossil fish teeth/debris pl otted versus meter composite depth (mcd) across the Late Cretaceous from OD P Sites 1258 at Demerara Rise.

PAGE 67

67 Figure 4-2. Nd(t) values from fossil fish teeth/debris pl otted versus meter composite depth (mcd) across the Late Cretaceous from OD P Sites 1260 at Demerara Rise. Figure 4-3. Nd(t) values from fossil fish teeth/debris versus depth (mcd) across the Late Cretaceous from ODP Sites 1261 at Demerara Rise.

PAGE 68

68 Figure 4-4. Nd(t) values versus age across the Early Paleogene and Late Cretaceous from ODP Sites 1258 (3192 m), 1260 (2549 m) and 1261 (1899 m) at Demerara Rise. The blue box represents OAE 2 and the purple box repr esents the MCE. Ages were estimated for the black shale interval using sedimentation rates of ~1 cm/k.y. for Site 1258, ~0.25 cm/k.y. for Site 1260 and ~1.5 cm /k.y. for Site 1261 (Erbacher et al., 2005) with the initiation of the event at 94.09 Ma (Sageman et al., 2006). Below and above the event, ages were estimated base d on interpolation/extrapolation along biostratigraphic best fit lines (Erbacher et al., 2004).

PAGE 69

69 Figure 4-5. Nd(t) values versus age across OAE 2 and MCE from ODP Sites 1258 (3192 m), 1260 (2549 m) and 1261 (1899 m) at Demerara Rise. The blue box represents OAE 2 and the purple box represents the MCE. Ages were estimated for the black shale interval using sedimentation rates of ~1 cm/k.y. for Site 1258, ~0.25 cm/k.y. for Site 1260 and ~1.5 cm/k.y. for Site 1261 (Erbacher et al., 2005) with th e initiation of the event at 94.09 Ma (Sageman et al., 2006). Below and above the event, ages were estimated based on interpolat ion/extrapolation along biostr atigraphic best fit lines (Erbacher et al., 2004).

PAGE 70

70 Figure 4-6. Nd(t) values versus age across OAE 2 from ODP Sites 1258 (3192 m), 1260 (2549 m) and 1261 (1899 m) at Demerara Rise. Ages were estimated for the black shale interval using sedimentation rates of ~1 cm/k.y. for Site 1258, ~0.25 cm/k.y. for Site 1260 and ~1.5 cm/k.y. for Site 1261 (Erbacher et al., 2005) with th e initiation of the event at 94.09 Ma (Sageman et al., 2006).

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71 Figure 4-7. Nd(t) and 13C values versus depth (mcd) across OAE 2 (blue box) and MCE (purple box) from ODP Site 1260. represents 13C data from Erbacher et al. (2005) and represents unpublished 13C data from MacLeod and Jimenez Berrocoso.

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72 Figure 4-8. High resolution Nd(t) and 13C values versus composite depth acro ss OAE 2 from ODP Sites 1258, 1260 and 1261. represents 13C data from Erbacher et al (2005). Point A represents the onset of OAE 2 based on 13C and point D represents the last maximum of the carbon excursion (Erbacher et al., 2005). There are 400 kyr betw een points A and D (Sageman et al., 2006).

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73 Table 4-2. Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site 1258 at Demerara Rise. Sample Depth (mcd) Age1 (Ma) Fish Teeth (Blair, 2006) Fe-Mn Oxide Coatings 143/144Nd2Nd(0) 3Nd(t) 4Error5 143/144Nd2 Nd(0) 3 Nd(t) 4Error5Site 1258A 42R -1, 8 414.83 92.62 0.511824-15.9-15.00.20.511854 -15.3 -14.80.2 42-6, 32 421.81 93.28 0.511834-15.7-14.80.10.511878 -14.8 -14.40.2 42R-7, 7 422.96 93.40 0.511967 -13.1 -12.2 0.1 0.511963 -13.2 -12.7 0.1 42R-7, 92 423.81 93.48 0.512074 -11.0 -10.2 0.2 0.512061 -11.3 -10.8 0.1 46R-2, 68 450.22 95.60 0.511833-15.7-14.80.20.511845 -15.5 -15.00.2 1. Ages for Site 1258 are from Erbacher, 2004, 2006. 2. 143/144Nd values are normalized to the JN di-1 average on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (TIMS average) 3. Nd(o) = [(143Nd/144Nd)sample/(143Nd/144Nd)CHUR-1] x 104 4. Nd(t) = [(143Nd/144Nd)sample(t)/(143Nd/144Nd)CHUR(t)-1] x 104 using 147Sm/144Nd = 0.125 for fish teeth and 0.129 for oxides 5. Listed errors indicate the w ithin run uncertainty. For all plots, a minimum error of 0.3 Nd unit is applied representing the 2 uncertainty of repeat analyses of JNdi-1. Blue highlighting represents OAE 2. Figure 4-9. Plot of Nd(t) values versus age before, during and after OAE 2 from ODP Site 1258 at Demerara Rise. The blue box represents OAE 2. Ages were estimated for the black shale interval using sedimentation rates of ~1 cm/k.y. for Site 1258 (Erbacher et al., 2005) with the initiation of the event at 94.09 Ma (Sageman et al., 2006). Below and above the event, ages were estimated based on interpolatio n/extrapolation along biostratigraphic best fit lines (Erbacher et al., 2004).

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74 Figure 4-10. Fe-Mn oxide coating REE patterns from ODP Site 1258 at Demerara Rise. Samples are normalized to their initi al weight and PAAS (Taylor and McLellen, 1985). Nod-A and Nod-P represent USGS Fe-Mn oxide coatin gs standards. Values are dislplay in table 4-7.

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75Table 4-3. Blake Nose Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coati ngs from ODP Sites 1049, 1050 and 1052. Sample Depth (mbsf) Depth (mcd) Age1 (Ma) Fish Teeth Fe-Mn Oxide Coatings 143/144Nd2Nd(0) 3 Nd(t) 4error5 143/144Nd2Nd(0) 3Nd(t) 4error5Site 1049 (2682m) 1049A 10-2W 45-51 71.3858.3649.670.512129-9.9 -9.50.20.512125-10.0-9.60.1 1049A 13 1W 25-31 95.9882.9656.040.512186-8.8-8.40.1 1049A 15 1W 13-19 105.4692.4461.680.512170-9.1-8.70.2 1049A 16 2W 50-56 117.03104.0163.710.512162-9.3-8.80.1 1049A 16 4W 62-68 120.13107.1164.250.512196-8.6-8.10.1 1049A 17 2W 100-106 127.13114.1165.480.512222-8.1-7.60.1 1049A 18 1W 35-41 134.68121.6666.810.512192-8.7-8.20.1 1049A 18 1W 35-41 134.68121.6666.810.512187-8.8 -8.20.11049A 18 3W 100-106 135.33122.3166.920.512203-8.5-8.00.1 1049A 18 5W 70-76 141.03128.0172.380.512157-9.4 -8.70.10.512179-9.0-8.40.1 1049A 19 1W 24-30 144.17131.15104.90.512282-6.9-6.20.1 1049A 20 1W 30-36 153.83138.68110.150.512276-7.1-6.20.1 1049A 20 2W 124-130 155.78140.63111.210.512264-7.3-6.50.2 1049A 20 5W 24-30 159.73144.58112.680.512313-6.3-5.50.1 1049A 20 6W 40-46 161.43146.28112.920.512327-6.1 -5.10.20.512314-6.3-5.50.1 1049C 13x 2W 20-22 150.61148.58113.260.512339-5.8 -4.80.11049A 21 2W 50-56 165.13148.81113.440.512282-6.9-6.10.1 1049C 13x 3W 20-22 152.11150.08113.470.512304-6.5 -5.50.11049C 13x CC 39-40 153.63151.60113.620.512308-6.4 -5.40.11049A 22 1W 20-26 172.93156.61114.540.512276-7.1-6.20.1 Site 1050 (2311m) 1050A 19x 2W 20-26 174.13177.5551.190.512184-8.9-8.50.1 1050A 21x 3W 60-66 193.23196.9452.480.512177-9.0-8.60.1 1050A 23x 5W 10-16 214.93217.9053.940.512237-7.8-7.40.1

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76Table 4-3. Continued 1050A 27x 4W 20-26 246.43250.5856.060.512215-8.2-7.90.1 1050A 30x 6W 10-16 274.13278.2857.930.512187-8.8-8.40.1 1050C 2R 3W 10-16 330.23330.2358.760.512164-9.3-8.90.2 1050A 35x 5W 120-126 312.13316.2860.490.512192-8.7-8.30.2 1050C 9 2W 102-108 397.05397.0564.170.512176-9.0-8.60.2 1050C 13 2W 22-28 425.04425.0466.630.512177-9.0-8.60.1 1050C 15 2W 10-16 444.23444.2368.340.512180-8.9-8.50.1 1050C 17 3W 9-15 464.92464.9270.150.512167-9.2-8.70.1 1050C 18 2W 59-65 473.52473.5271.110.512153-9.5-9.00.1 1050C 18 2W 130-132 474.21474.2171.190.512176-9.0 -8.40.2*1050C 20 1W 30-36 490.93490.9376.990.512179-9.0 -8.30.00.512173-9.1-8.60.1 1050C 20-4W 29-32 495.40495.4091.740.512308-6.4 -5.60.21050C 20 4W 120-121 495.60495.6091.810.512320-6.2 -5.40.11050C 20 5W 40-42 497.02497.0292.310.512317-6.3 -5.40.11050C 21 1W 20-21 500.40500.4093.310.512332-6.0 -5.10.11050C 21-1W 42-43 500.62500.6293.390.512330-6.0 -5.20.11050C 21 1W 47-48 500.67500.6793.400.512332-6.0 -5.10.1 1050C 21 1W 56.5-57.5 500.77 500.77 93.44 0.512370 -5.2 -4.4 0.1 1050C 21 1W 68-69 500.88 500.88 93.48 0.512337 -5.9 -5.0 0.1 1050C 21 1W 72-73 500.92 500.92 93.86 0.512325 -6.1 -5.3 0.1 1050C 21 1W 105-108 501.26501.2693.890.512332-6.0 -5.10.11050C 21-1W 120-121 501.45501.4593.910.512340-5.8 -5.00.11050C 21 7W 45-46 508.75508.7594.630.512311-6.4 -5.50.11050C 22 1W 46-50 510.28510.2894.780.512308-6.4 -5.60.21050C 23 4W 60-64 524.52524.5296.180.512295-6.7 -5.80.11050C 23 6W 126-129 528.17528.1796.540.512359-5.4 -4.60.11050C 24-2W 69-72 531.30531.3096.850.512351-5.6 -4.70.1

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77Table 4-3. Continued 1050C 25 1W 82-85 539.53539.5397.660.512354-5.5 -4.70.21050C 25-3W 60-64 542.32542.3297.940.512344-5.7 -4.90.11050C 26 1W 53-56 548.94548.9498.590.512308-6.4 -5.60.11050C 26 4W 140-142 554.31554.3199.120.512337-5.9 -5.00.11050C 27 1W 73-76 558.74558.7499.680.512365-5.3 -4.40.1*1050C 27 2W 100-106 560.53560.5399.770.512349-5.6 -4.70.00.512324-6.1-5.50.1 1050C 277W 20-22 567.21567.21100.110.512290-6.8 -5.90.11050C 28 1W 70-73 568.31568.31100.160.512355-5.5 -4.60.21050C 28 4W 102-108 573.16573.16100.400.512300-6.6-5.90.1 1050C 28 4W 146-150 573.58573.58100.430.512351-5.6 -4.70.1*1050C 29 2W 100-106 579.73579.73100.740.512334-5.9 -5.00.00.512303-6.5-5.90.1 1050C 29 2W 132-135 580.03580.03100.750.512297-6.7 -5.70.11050C 29 5W 72-75 583.93583.93100.950.512339-5.8 -4.90.11050C 31 1W 132-134 597.73597.73101.640.512359-5.4 -4.50.11050C 31 2W 100-106 598.93598.93101.700.512298-6.6 -5.70.1*1050C 31 2W 100-106 598.93598.93101.700.512337-5.9 -5.00.01050C 31-6W 78-83 604.70604.70101.990.512367-5.3 -4.40.1Site 1052 (1356m) 1052B 5 3W 98-104 37.5340.8636.360.512211-8.3 -8.00.10.512194-8.7-8.40.1 1052B 11 5W 20-26 87.7392.9137.360.512172-9.1-8.80.1 1052E 1 1W 50-56 140.53140.5341.400.512156-9.4 -9.00.10.512154-9.4-9.10.1 1052E 6 1W 30-32 185.11185.1145.970.512172-9.1-8.60.1 1052E 16 4W 12-18 285.53285.5363.360.512204-8.5-8.00.1 1052E 19 1W 50-56 301.63301.6364.320.512233-7.9-7.40.1 1052E 21 3W 45-46 332.35332.3567.590.512238-7.8 -7.20.11052E 24 2W 20-26 359.63359.6368.190.512225-8.1-7.60.1 1052E 28 1W 100-106 397.33397.3369.030.512223-8.1-7.60.1

PAGE 78

78Table 4-3. Continued 1052E 35 2W 100-106 466.13466.1370.910.512189-8.8-8.20.1 1052E 36 4W 111-114 478.82478.8294.820.512377-5.1 -4.20.21052E 36 5W 19-25 479.42479.4294.940.512358-5.0 -4.60.10.512337-5.9-5.20.1 1052E 38 1W 20-26 492.63492.6398.370.512398-4.7 -3.80.10.512377-5.1-4.40.1 1052E 38 1W 65-66 493.05493.0598.400.512376-5.1 -4.20.11052E 40 1W 71-74 511.32511.3299.630.512377-5.1 -4.20.11052E 41 1W 10-16 520.43520.4399.910.512379-5.1-4.30.1 1052E 41 1W 40-41 520.70520.7099.920.512403-4.6 -3.70.21052E 41 2W 50-52 522.31522.3199.970.512399-4.7 -3.80.21052E 42 2W 109-112 532.50532.50100.390.512376-5.1 -4.20.21052E 44 5W 68-69.5 555.79555.79101.240.512404-4.6 -3.70.21052E 44 CC 10-12 558.21558.21101.370.512421-4.2 -3.30.11052E 46 1W 20-26 568.53568.53101.280.512377-5.1-4.30.1 1052E 46 6W 3-4.5 575.84575.84101.510.512409-4.5 -3.60.11052E 481W 91-94 588.52588.52101.910.512430-4.1 -3.10.11052E 49 1W 120-122 598.51598.51102.230.512414-4.4 -3.50.11052E 52 2W 20-26 623.43623.43103.020.512404-4.6-3.80.1 1052E 57 5W 50-56 672.13672.13104.560.512380-5.0-4.30.0 1052 E 58 CC 676.88676.88104.710.512402-4.6 -3.70.2 1. Ages for Sites 1049, 1050 and 1052 are from Huber et al., 1999, Petrizzio et al., 2008 and Shipboard Scientific Party, 1997. 2. 143/144Nd values are normalized to the JNdi-1 av erage on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (T IMS average) 3. Nd(o) = [(143Nd/144Nd)sample/(143Nd/144Nd)CHUR-1] x 104 4. Nd(t) = [(143Nd/144Nd)sample(t)/(143Nd/144Nd)CHUR(t)-1] x 104 using 147Sm/144Nd = 0.125 for fish teeth at all Sites; 0.138 for coatings at Sites 1049 and 1052 and 0.157 for coatings at Site 1050. 5. Listed errors indicate the w ithin run uncertainty. For all plots, a minimum error of 0.3 Nd unit is applied representing the 2 uncertainty of repeat analyses of JNdi-1. indicates samples from Blair (2006). Blue highlighting represents OAE 2.

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79 Figure 4-11. ODP Sites 1049 at Blake Nose: Nd(t) versus depth (mcd) across the Late Cretaceous. Figure 4-12. ODP Sites 1050 at Blake Nose: Nd(t) versus depth (mcd) across the Late Cretaceous.

PAGE 80

80 Figure 4-13. ODP Sites 1052 at Blake Nose: Nd(t) versus depth (mcd) across the Late Cretaceous.

PAGE 81

81 Figure 4-14. Nd(t) values versus age (Ma) across the La te Cretaceous and early Cenozoic from ODP Sites 1049, 1050 and 1052 at Blake Nose. Ages were estimated based on interpolation/extrapolation al ong biostratigraphic best fit lines from Huber et al. (2002) and Petrizzo et al. (2008) for the Albian and Cenomanian at Sites 1050 and 1052. For Site 1049 in the Aptian-Albian and all three sites for th e younger part of the record, ages were estimated based on interpolation/extrapolation along biostratigraphic best fit lines from No rris et al. (1998), Hube r et al. (1999) and Huber et al. (2002).

PAGE 82

82 Figure 4-15. Nd(t) and 13C of benthic foraminifera (Huber et al., 1999) values versus depth across OAE 2 from ODP Site1050 at Blake No se. The blue box represents OAE 2 and dash lines represent hiatus in the section at 500.96, 500.93, 550.89, 500.83 and 500.76 mbsf (Huber et al., 1999).

PAGE 83

83Table 4-4. Goban Spur Nd isotopic valu es from Fossil Fish Teeth and Fe-Mn Ox ide Coatings from ODP Sites 549, 550 and 551. Sample Depth (mbsf) Age1 Fish Teeth Fe-Mn Oxide Coatings 143/144Nd2 Nd(0) 3 Nd(t) 4Error5 143/144Nd2Nd(0) 3Nd(t) 4Error5Site 549 (2515m) 549 7R 2W 49-60 247.05 mid Eocene 0.512138-9.8-9.60.1 549 15R 2W 68-70 324.05 early Eocene 0.512252-7.5-7.30.1 549 19R 2W 50-60 362.05 late Paleocene 0.512198-8.6-8.30.1 549 21R 1W 50-56 379.55 late Maastrichtian 0.512207-8.4-8.10.1 549 21R 1W 70-80 379.75 late Maastric htian 0.512263-7.3 -6.80.10.512153-9.5-9.20.1 549 22R 2W 50-60 390.55 early Maastrichtian 0.512096-10.6-10.30.1 549 22R 5W 65-75 395.05 early Maastrichtian 0.512139-9.7-9.40.1 549 23R 2W 30-40 399.85 late Campanian 0.512117-10.2-9.80.1 549 23R 5W 50-60 404.55 late Campanian 0.512094-10.6-10.30.1 549 24R 1W 55-65 408.05 Santonian 0.512188-8.8-8.40.1 549 24R 3W 50-60 411.05 Santonian 0.512165-9.2-8.90.2 549 25R 1W 50-60 417.55 San.-Coniacian 0.512228-8.0-7.60.1 549 25R 2W 50-60 419.05 San.-Coniacian 0.512190-8.7-8.40.1 549 26R 1W 40-48 426.94 San.-Coniacian 0.512178-9.0-8.60.1 549 27R 1W 10-18 436.14 Turonian 0.512198-8.6 -7.90.10.512205-8.5-8.00.1 549 27R 1W 43-50 436.55 OAE 2 ? 0.512254 -7.5 -7.1 0.1 549 28R 1W 10-18 445.64 Cenomanian 0.512212-8.3-7.90.1 549 28R 1W 70-80 446.25 Cenomanian 0.512171-9.1-8.70.1 549 28R 2W 75-85 447.80 Cenomanian 0.512147-9.6-9.20.2 549 28R 3W 10-12 448.65 Cenomanian 0.512176-9.0-8.60.2 549 29R 1W 2-12 455.57 Cenomanian 0.512150-9.5-9.10.1 549 32R 1W 10-20 483.61 mid Albian 0.512212-8.3-7.90.1 549 34R 1W 50-60 503.05 mid Albian 0.512203-8.5-8.10.1

PAGE 84

84Table 4-4. Continued Site 550 (4420m) 550 29-1W 100-104 357.00 Paleocene 0.512259-7.4 -7.00.10.512232-7.9-7.70.1 550B 3-1W 45-49 475.45 Paleocene 0.512107-10.4-10.10.1 550 47-1W 60-64 522.60 Paleocene 0.512191-8.7 -8.20.10.512140-9.7-9.40.2 550B 8 2W 50-56 524.52 late Maastrichtian 0.512113-10.2-9.90.1 550B 10 1W 100-106 542.49 late Maastrichtian 0.512161-9.3-9.00.1 550B 11 1W 50-56 551.44 early Maastrichtian 0.512119-10.1-9.80.1 550B 15 2W 20-26 590.73 Coniacian 0.512225-8.1-7.70.1 550B 17-2W 17-21 609.67 Turo.-Cenomanian 0.512175-9.0-8.60.2 550B 17 2W 20-26 609.67 Cenomanian 0.512190-8.7-8.30.1 550B 21-3W 20-24 647.20 Cenomanian 0.512235-7.9 -7.10.1 550B 22-4W 23-27 657.73 Cenomanian 0.512209-8.4-7.90.1 550B 24 1W 20-26 671.23 late Albian 0.512222-8.1 -7.30.10.512226-8.0-7.60.1 550B 25-1W 26-30 680.26 late Albian 0.512230-8.0-7.70.1 Site 551 (3887m) 551 2-3W 53-63 107.58 early Maastrichtian 0.512186-8.8 -8.30.1 551 4-1W 125-135 124.30 late Campanian 0.512096-10.6 -9.90.1 551 5-1W 10-18 132.64 early Turonian 0.512300-6.6 -5.90.1 551 5-1W 117-126 133.72 early Turonian 0.512291-6.8 -6.00.1 551 5-2W 7-17 134.12 OAE 2 0.512259 -7.4 -6.7 0.1 551 5-2W 40-48 134.44 OAE 2 0.512343 -5.8 -5.0 0.2 551 5-2W 75-81 134.77 OAE 2 0.512278 -7.0 -6.3 0.1 551 5-2W 100-105 135.02 OAE 2 0.512290 -6.8 -6.1 0.1 551 6-1W 8-15 138.62 late Cenomanian 0.512147-9.6 -8.80.1 551 6-1W 110-118 139.64 late Cenomanian 0.512189-8.8 -8.00.1 551 6-2W 50-60 140.55 late Cenomanian 0.512187-8.8 -8.00.1 551 6-3W 50-60 142.05 late Cenomanian 0.512241-7.7 -7.00.1

PAGE 85

851. Ages for Site 549, 550 and 551 are from Shipboard Scientific Party, 1985. 2. 143/144Nd values are normalized to the JNdi-1 av erage on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (T IMS average) 3. Nd(o) = [(143Nd/144Nd)sample/(143Nd/144Nd)CHUR-1] x 104 4. Nd(t) = [(143Nd/144Nd)sample(t)/(143Nd/144Nd)CHUR(t)-1] x 104 using 147Sm/144Nd = 0.134 for fish teeth and 0.162 for coatings the three sites. 5. Listed errors indicate the w ithin run uncertainty. For all plots, a minimum error of 0.3 Nd unit is applied representing the 2 uncertainty of repeat analyses of JNdi-1. Blue highlighting represents OAE 2.

PAGE 86

86 Figure 4-16. ODP Site 549 at Goban Spur: Nd(t) values versus depth across the Late Cretaceous. Figure 4-17. ODP Site 550 at Goban Spur: Nd(t) values versus depth across the Late Cretaceous.

PAGE 87

87 Figure 4-18. ODP Site 551 at Goban Spur: Nd(t) values versus depth across the Late Cretaceous.The blue box represents OAE 2. All the samples analyzed were fossil fish teeth and debris. No core was recovered for the interval from 135.67 to 138.67 mbsf.

PAGE 88

88 Figure 4-19. Nd(t) and 13C (bulk sediment, Gustafsson et al ., 2003) values versus depth across OAE from ODP Site 551 at Goban Spur. Th e blue box represents OAE 2. No core was recovered for the interval from 135.67 to 138.67 mbsf.

PAGE 89

89Table 4-5. Bermuda Rise Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site 386. Sample Depth (mbsf) Age1 (Ma) Fish Teeth Fe-Mn Oxide Coatings 143/144Nd2Nd(0) 3Nd(t) 4 Error5 143/144Nd2Nd(0) 3Nd(t) 4Error5Site 386 (2515m) 386 35R 2W 9-11 633.60 Camp.-Maastr. 0.512079-10.9-10.5 0.2386 35R 2W 91-94 634.42 Camp.-Maastr. 0.512104-10.4-10.0 0.1386 36R 1W 113-115 642.64 Camp.-Maastr. 0.512209-8.4-8.0 0.2386 38R 3W 75-77 692.66 Turo.-Maastr. 0.512224-8.1-7.60.1 386 41R 1W 48-50 717.99 Turo.-Maastr. 0.512266-7.3-6.80.8 386 41R 2W 72-75 719.73 Turo.-Maastr. 0.512247-7.6-7.10.2 386 41R 3W 45-49 720.97 Turo.-Maastr. 0.512242-7.7-7.20.2 386 41R 5W 78-80 724.29 Turo.-Maastr. 0.512235-7.9-7.30.2 386 43R 2W 82-84 738.73 Turonian 0.512286-6.9-6.30.4 386 43R 2W 97-99 738.83 OAE 2 0.512296 -6.7 -6.1 0.3 386 43R 2W 112-114 738.93 OAE 2 0.512366 -5.3 -4.7 0.6 386 43R 2W 122-124 739.03 OAE 2 0.512315 -6.3 -5.7 0.5 386 43R 2W 146-148 739.27 Cenomanian 0.512269-7.2-6.6 0.20.512278-7.0-6.40.2 386 43R 3W 115-117 740.46 Cenomanian 0.512281-7.0-6.4 0.30.512313-6.3-5.80.1 386 43R 4W 7-9 740.88 Cenomanian 0.512281-7.0-6.4 0.4386 45R 4W 70-73 770.02 Cenomanian 0.512261-7.4-6.8 0.2386 49R 2W 146-148 804.77 Ceno.-Albian 0.512254-7.5-6.9 0.1386 49R3W 41-43 806.22 Ceno.-Albian 0.512229-8.0-7.4 0.2386 50R 1W 71-73 813.01 Ceno.-Albian 0.512222-8.1-7.5 0.2386 50R 5W 123-125 818.54 Ceno.-Albian 0.512214-8.3-7.7 0.2 1. Ages for Site 386 are from Shipboard Scientific Party, 1975. 2. 143/144Nd values are normalized to the JNdi-1 av erage on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (T IMS average) 3. Nd(o) = [(143Nd/144Nd)sample/(143Nd/144Nd)CHUR-1] x 104 4. Nd(t) = [(143Nd/144Nd)sample(t)/(143Nd/144Nd)CHUR(t)-1] x 104 using 147Sm/144Nd = 0.147 for fish teeth and 0.148 for coatings.

PAGE 90

905. Listed errors indicate the w ithin run uncertainty. For all plots, a minimum error of 0.3 Nd unit is applied representing the 2 uncertainty of repeat analyses of JNdi-1. Blue highlighting represents OAE 2.

PAGE 91

91 Figure 4-20. Nd(t) values across the Late Cretaceous fr om ODP Site 386 at Bermuda Rise. The blue box represents OAE 2. The dash lines indicate that the core did not recover for this interval.

PAGE 92

92 Figure 4-21. Nd(t) and 13Corg (MacLeod and Jimenez Berrocoso, unpublished data) values across the OAE 2 from ODP Site 386 at Be rmuda Rise. The blue box represents OAE 2.

PAGE 93

93Table 4-6. Cape Verde Nd isotopic values from Fossil Fish Teeth and Fe-Mn Oxide Coatings from ODP Site 367. Sample Depth (mbsf) Age1 (Ma) Fish Teeth Fe-Mn Oxide Coatings 143/144Nd2Nd(0) 3 Nd(t) 4Error5 143/144Nd2Nd(0) 3Nd(t) Error5Site 367 (m) 367 17R 1W 121-124 617.22 Maastr.-Campanian 0.512164-9.1 -8.70.20.512062-11.2-10.70.3 367 17-2W -56 618.06 Maastr.-Campanian 0.512180-8.9-8.40.3 367 17-3W 66-69 619.68 Maastr.-Campanian 0.512157-9.4-8.80.4 367 17 4W 32-36 620.84 Maastr.-Campanian 0.512089-10.7-10.10.3 367 17R 4W 137-139 621.88 Maastr.-Campanian 0.512119-10.0 -9.40.10.512119-10.1-9.50.2 367 18R 1W 63-69 636.63 OAE 2 0.512158 -9.2 -8.6 0.1 0.512139 -9.7 -9.0 0.1 367 18 1W 117-124 637.20 OAE 2 0.512217 -8.2 -7.5 0.3 367 18-2W 5-7 637.56 OAE 2 0.512195 -8.6 -8.0 0.2 367 18R 2W 71-73 638.22 OAE 2 0.512149 -9.4 -8.8 0.1 0.512148 -9.6 -8.9 0.2 367 18R 3W 20-22 639.21 OAE 2 0.512186 -8.6 -8.0 0.2 0.512209 -8.4 -7.7 0.2 367 18R 4W 23-26 640.74 OAE 2 0.512170 -9.0 -8.3 0.1 0.512158 -9.3 -8.7 0.2 367 18-4W 87-90 641.49 OAE 2 0.512155 -9.3 -8.6 0.2 0.512268 -7.2 -6.5 0.2 367 19-3W 24-27 647.76 Ceno.-Albian 0.512137-9.6 -9.00.40.512122-9.9-9.40.4 367 20R 2W 24-27 691.20 Ceno.-Albian 0.512117-10.0 -9.40.10.512117-10.0-9.50.1 367 20 3W 125-128 693.80 Ceno.-Albian 0.512145-9.4-8.90.1 367 20R 4W 47-50 694.50 Ceno.-Albian 0.512163-9.1 -8.50.20.512118-10.0-9.40.1 367 20R 4W 96-100 695.00 Ceno.-Albian 0.512093-10.5 -9.80.10.512107-10.2-9.70.2 1. Ages for Site 367 are from Shipboard Scientific Party, 1975 2. 143/144Nd values are normalized to the JNdi-1 av erage on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (T IMS average) 3. Nd(o) = [(143Nd/144Nd)sample/(143Nd/144Nd)CHUR-1] x 104 4. Nd(t) = [(143Nd/144Nd)sample(t)/(143Nd/144Nd)CHUR(t)-1] x 104 using 147Sm/144Nd = 0.130 for fish teeth and 0.138 for coatings. 5. Listed errors indicate the w ithin run uncertainty. For all plots, a minimum error of 0.3 Nd unit is applied representing the 2 uncertainty of repeat analyses of JNdi-1. Blue highlighting represents OAE 2

PAGE 94

94 Figure 4-22. Nd(t) values versus depth across the Late Cretaceous from ODP Site 367 at Cape Verde. The blue box represents OAE 2.

PAGE 95

95 Figure 4-23. Nd(t) and 13C values versus depth across the OAE 2 at ODP Site 367 at Cape Verde. The blue box represents OAE 2. Delta13C values from bulk carbonate by MacLeod and Jimenez Berrocoso (Unpublishe d data) and from bulk organic matter by Forster et al. (2007)

PAGE 96

96Table 4-7. REE values extracted from Fe-Mn oxide samples and normalized to PAAS from USGS Standards and ODP Site 367, 386, 550, 1049, 1050, 1052, 1258 and 1260. Samples La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Fe-Mn Nodules *Nod-A 3.16 9.13 2.532.943.754.555.585.585.235.354.214.945.005.58 *Nod-P 2.74 3.63 3.093.755.366.826.016.236.145.654.214.204.644.19 Nod-A 2.77 8.73 2.522.953.664.725.344.805.034.694.925.004.644.81 Nod-P 2.64 3.71 3.323.975.406.946.405.945.814.754.694.684.444.27 Site 1260 B 23 6W 130-132 0.11 0.09 0.080.090.090.110.120.130.150.150.170.180.180.18 B 26 7W 10-12 6.51 9.19 11.9515.3821.5323.2123.5419.1318.3514.6214.0511.8910.409.74 B 35 2W 120-121 0.29 0.15 0.210.280.310.390.450.350.380.410.450.410.390.45 B 35 4W 103-104 3.52 2.98 5.076.478.7211.7710.728.918.326.655.904.703.703.24 B 35 5W 46-47 0.05 0.02 0.020.030.030.040.040.040.050.060.080.100.130.16 A 48 4W 10-12 0.05 0.03 0.040.050.050.060.070.060.070.080.090.100.110.12 Average 1.76 2.08 2.903.715.125.935.824.774.553.663.462.902.482.32 Site 1258 42R-1W 8 1.19 0.59 0.981.231.241.531.861.511.511.591.551.401.021.27 42R-6W 32 0.11 0.07 0.090.110.120.150.150.140.120.130.130.150.130.19 42R-7W 7 0.62 0.48 0.780.951.231.591.561.501.341.351.221.410.931.33 42R-7W 92 1.39 1.15 1.952.483.424.744.503.953.903.583.393.112.532.58 46R-2W 68 0.03 0.02 0.030.030.030.200.050.100.050.090.070.140.050.19 Average 0.67 0.46 0.770.961.211.641.621.441.391.351.271.240.931.11 Site 1049A 16 2W 50-56 2.22 2.13 3.624.877.148.187.605.695.153.943.623.032.552.23 16 4W 62-68 0.90 0.78 1.552.123.123.763.352.582.321.821.681.421.211.08 20 1W 30-36 6.99 5.71 10.2613.5916.9619.7822.5217.7616.6314.3712.8810.007.666.85 20 5W 24-30 4.61 3.00 6.648.259.8111.2011.839.358.577.286.565.194.003.62

PAGE 97

97Table 4-7. Continued 21 2W 50-56 3.34 1.41 4.085.276.017.378.176.376.295.435.013.892.902.62 Average 3.61 2.61 5.236.828.6110.0610.708.357.796.575.954.713.663.28 Site 1050 2R 3W 10-16 1.27 1.61 2.473.335.085.905.454.343.772.912.662.281.931.79 13R 2W 22-28 0.37 0.39 0.660.871.261.501.481.221.110.930.850.740.610.57 15R 2W 10-16 0.76 0.72 1.612.223.324.043.873.042.682.101.851.481.191.10 17R 3W 9-15 1.74 0.87 3.094.225.857.167.626.125.684.694.113.222.492.31 18R 2W 59-65 0.09 0.05 0.130.180.250.390.320.260.240.200.200.160.140.13 20R 1W 30-36 0.51 0.35 0.921.271.892.372.181.711.551.241.120.930.790.73 22R 1W 9-15 2.35 1.53 3.514.826.988.868.987.256.925.955.484.603.803.60 25R 2W 80-86 0.16 0.17 0.300.390.570.650.660.530.480.380.340.280.220.21 27R 2W 100-106 0.25 0.36 0.520.721.211.581.260.970.820.650.590.490.430.42 28R 4W 102-108 1.80 2.16 3.194.366.527.907.926.415.844.894.503.703.032.97 29R 2W 100-106 3.73 3.96 5.938.0411.1813.6313.9611.4110.699.228.517.085.795.65 31R 2W 100-106 2.91 3.82 5.537.6011.9214.4513.8711.4210.148.167.326.094.964.71 Average 1.33 1.33 2.323.174.675.705.634.564.163.443.132.592.122.02 Site 1052E 24 2W 20-26 0.90 0.96 1.652.283.434.174.153.423.262.742.572.161.871.82 28 1W 100-106 0.29 0.17 0.310.400.470.580.660.540.550.500.470.390.310.30 35 2W 100-106 2.20 1.33 3.645.147.549.3610.218.067.896.706.064.843.893.67 36 5W 20-26 0.07 0.05 0.070.070.080.100.100.090.100.090.100.100.090.09 38 1W 20-26 3.02 3.93 6.068.1111.0012.2012.219.368.316.445.634.193.222.95 41 1W 10-16 0.30 0.30 0.370.450.540.660.670.550.530.460.430.350.280.26 Average 1.13 1.13 2.022.743.844.514.673.673.442.822.542.001.611.51 Site 550 8 2W 50-56 0.98 1.06 1.571.912.422.832.812.342.111.621.411.090.860.74 10 1W 100-106 0.43 0.71 1.131.582.693.212.762.171.761.221.020.790.660.60

PAGE 98

98Table 4-7. Continued 11 1W 50-56 1.15 0.98 1.752.122.633.113.132.562.381.871.661.311.040.89 15 2W 20-26 1.05 1.82 2.483.355.996.525.844.834.213.082.832.552.272.10 17 2W 20-26 0.63 0.55 1.321.873.013.603.142.311.941.401.190.930.770.68 24 1W 20-26 1.16 1.10 2.032.854.435.824.883.673.122.412.141.651.371.27 Average 0.90 1.04 1.712.283.534.183.762.982.591.931.711.391.161.05 Site 386 38 3W 75-76.5 0.13 0.29 0.350.510.901.070.910.750.650.480.440.380.340.31 41 5W 78-80 0.04 0.07 0.100.130.210.270.210.170.150.110.100.080.070.06 43 2W 82-84 0.02 0.02 0.010.010.020.030.020.010.010.010.010.010.010.01 43 2W 146-147.5 0.03 0.02 0.030.040.050.140.060.050.050.040.040.040.040.04 Average 0.05 0.10 0.130.170.290.380.300.240.210.160.150.130.110.11 Site 367 17 1W 121-124 0.01 0.04 0.030.030.050.240.040.040.030.030.030.040.040.04 17 4W 32-35.5 0.02 0.04 0.040.040.060.280.050.040.030.030.020.030.030.02 18 1W 117-124 0.15 0.04 0.060.050.061.190.060.050.050.050.050.050.060.06 18 2W 71-73 1.14 0.61 1.241.692.334.103.422.903.153.163.373.223.073.14 Average 0.33 0.18 0.340.460.621.450.900.750.820.820.870.830.800.82 Samples normalized to initial weight and then PAAS (Taylor and McLellen, 1985). *USGS CRM, certified reference material va lues (Flanagan and Gottfried, 1980). Error is +/5%

PAGE 99

99 Figure 4-24. Fe-Mn oxide coati ng REE patterns from ODP Site 1049 at Blake Nose. Samples are normalized to their initial weight and PAAS (T aylor and McLellen, 1985). Nod-A and Nod-P represent USGS Fe-Mn oxide coatings standards. Figure 4-25. Fe-Mn oxide coati ng REE patterns from ODP Site 1050 at Blake Nose. Samples are normalized to their initial weight and PAAS (T aylor and McLellen, 1985). Nod-A and Nod-P represent USGS Fe-Mn oxide coatings standards.

PAGE 100

100 Figure 4-26. Fe-Mn oxide coati ng REE patterns from ODP Site 1052 at Blake Nose. Samples are normalized to their initial weight and PAAS (T aylor and McLellen, 1985). Nod-A and Nod-P represent USGS Fe-Mn oxide coatings standards. Figure 4-27. REE plots of the average values from Fe-Mn oxide coatings from ODP Sites 367, 386, 550, 1049, 1050, 1052, 1258 and 1260. Samples are normalized to their initial weight and PAAS (T aylor and McLellen, 1985). Nod-A and Nod-P represent USGS Fe-Mn oxide coatings standards.

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101Table 4-8. REE values of uncleaned fossil fish te eth normalized to PAAS from ODP Site 367, 386 and 1260. La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Site 1260 B 32-2W 32-34 4.16 2.89 3.81 4.23 4.50 5.06 5.52 4.74 4.78 4.62 4.88 4.67 4.17 4.27 B 35-3W 41-45 7.79 6.47 9.25 10.99 12.73 15.32 15.54 12.60 12.09 10.54 10.48 8.25 6.75 6.16 B 35-4W 52-54 12.58 6.33 10.49 11.98 13.37 16.43 19.15 16.39 17.53 16.93 17.00 14.85 12.68 12.43 B 35-5W 46-47 13.58 6.65 9.11 10.30 10.84 13.73 16.07 14.62 16.80 17.70 20.09 20.98 20.31 20.73 B 35-5W 90-92 15.24 12.49 17.83 20.31 23.17 27.10 28.85 25.19 25.32 22.76 22.05 19.26 15.54 14.48 A 49-1W 82-84 4.53 3.30 3.76 4.12 4.15 5.18 5.59 5.05 5.54 5.54 5.99 5.59 4.58 4.57 A 49-2W 40-41 5.83 2.87 4.01 4.63 5.11 6.42 7.84 7.38 8.73 9.62 10.88 11.04 9.91 10.43 Site 386 35R-2W 9 -11 36.33 46.51 52.78 59.30 75.00 90.60 87.99 84.82 78.89 71.95 68.38 69.44 55.29 62.86 35R-2W 91-94 43.42 68.01 71.63 80.88 104.45124.50125.26117.86 112.8299.79 94.63 93.52 76.98 79.18 36R-1W 113-115 47.16 90.55 90.28 104.78144.93170.17168.67157.25 146.07117.11101.6787.07 64.51 61.57 43R 2W 112-114 0.08 0.11 0.07 0.07 0.10 0.24 0.11 0.06 0.08 0.07 0.06 0.09 0.06 0.05 43R 2W 146-148 0.36 0.41 0.59 0.78 1.30 2.01 2.25 2.49 3.04 2.93 3.09 3.37 3.37 3.25 43R 3W 115-117 0.08 0.28 0.17 0.24 0.35 0.47 0.48 0.43 0.46 0.41 0.41 0.40 0.36 0.32 43R 4W 7-9 0.01 0.05 0.03 0.05 0.08 0.10 0.08 0.06 0.07 0.06 0.06 0.07 0.07 0.06 45R-2W 70-73 62.52 60.63 68.26 77.97 97.94 124.70134.81123.79 126.29110.17101.2384.31 60.55 52.12 49R-2W 146-148 120.85 138.61 188.04228.68316.88389.93389.69352.46 327.06268.93237.21204.52152.83151.62 49R-3W 41-42 104.28 126.91 158.46188.84254.24309.64311.63282.80 260.66217.79189.90169.47124.05128.12 50R-1W 71-72 80.68 99.83 120.82145.27194.58239.49240.84217.40 200.06166.92145.68126.2193.60 92.94 50R-5W 123-125 86.76 114.43 118.99141.25185.77227.86233.38219.97 201.13176.67156.50147.64104.82121.88

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102Table 4-8. Continued Site 367 20R 4W 47-50 20.75 7.88 16.87 19.72 21.45 29.03 32.80 30.49 32.40 32.73 33.49 33.03 29.01 28.03 20R 2W 24-27 29.73 26.60 42.47 50.62 62.69 72.88 73.24 63.87 59.79 51.25 48.11 42.92 37.09 34.98 18R 4W 88-91 10.16 4.48 8.35 10.70 14.37 21.15 25.68 26.50 32.19 36.93 43.57 48.92 50.55 56.43 17R 4W 137-139 6.62 6.37 6.41 7.07 8.17 9.62 11.02 10.53 11.11 10.37 10.71 10.61 9.38 9.08 17R 1W 121-124 1.29 0.46 2.27 2.71 3.17 4.05 4.09 3.82 3.96 3.73 3.81 3.78 3.27 3.19 Samples normalized to initial weight and then PAAS (Taylor and McLellen, 1985).

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103 Figure 4-28. Fish teeth REE patte rns from ODP Site 367 at Cape Verde. Samples are normalized to their initial weight and PAAS (Taylor and McLellen, 1985). Figure 4-29. Fish teeth REE patterns from ODP Site 386 at Bermuda Rise. Samples are normalized to their initial weight and PAAS (Taylor and McLellen, 1985).

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104 Figure 4-30. Fossil fish teeth REE patterns from ODP Site 1260 at Demerara Rise. Samples are normalized to their initial weight an d PAAS (Taylor and McLellen, 1985).

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105 Table 4-9. Nd and Sr isotopic values from fo ssil fish teeth and Fe-Mn oxide coatings and residual fraction from ODP Site 1260 at Demerara Rise. Sample Depth (mcd) Age1 (Ma) 143/144Nd2Nd(0) 3Nd(t) 4Error5 87/86Sr6 Error Site 1260 Fish teeth B 26-7W 10-12 366.81 72.70 0.511815-16.1 -15.4 0.2 B 35-2W 120-121 418.00 92.64 0.511831-15.7 -14.9 0.2 B 35-4W 103-104 420.77 93.70 0.512051 -11.4 -10.6 0.1 B 35-5W 46-47 421.67 94.03 0.511933 -13.8 -12.9 0.1 A 48-4W 10-12 438.15 95.54 0.511892-14.6 -13.7 0.1 A 52-4W 130-132 483.00 98.71 0.511947-13.5 -12.6 0.2 Fe-Mn oxide coatings B 26-7W 10-12 366.81 72.70 0.511782-16.7 -16.0 0.2 0.7077460.000009 B 35-2W 120-121 418.00 92.64 0.511806-16.2 -15.7 0.1 0.7075500.000008 B 35-4W 103-104 420.77 93.70 0.512018 -12.1 -11.1 0.1 0.707737 0.000031 B 35-5W 46-47 421.67 94.03 0.511928 -13.9 -13.2 0.1 0.707489 0.000009 A 48-4W 10-12 438.15 95.54 0.511903-14.3 -13.3 0.1 0.7075370.000010 A 52-4W 130-132 483.00 98.71 0.511914-14.1 -13.1 0.1 Residual fraction B 26-7W 10-12 366.81 72.70 0.511633-19.0 -18.7 0.1 0.7086570.000006 B 35-2W 120-121 418.00 92.64 0.511836-14.8 -14.5 0.4 0.7088810.000009 B 35-4W 103-104 420.77 93.70 0.511765 -16.2 -15.9 0.1 0.708640 0.000015 B 35-5W 46-47 421.67 94.03 0.709219 0.000008 A 48-4W 10-12 438.15 95.54 0.511805-15.4 -15.0 0.2 0.7103890.000015 1. Ages for Site 1260 are from Erbacher, 2004. 2. 143/144Nd values are normalized to the JN di-1 average on the day the samples were analyzed and then normalized to JNdi-1 = 0.512103 (TIMS average) 3. Nd(o) = [(143Nd/144Nd)sample/(143Nd/144Nd)CHUR-1] x 104 4. Nd(t) = [(143Nd/144Nd)sample(t)/(143Nd/144Nd)CHUR(t)-1] x 104 using 147Sm/144Nd = 0.125 5. Listed errors indicate the w ithin run uncertainty. For all plots, a minimum error of 0.3 Nd unit is applied representing the 2 uncertainty of repeat analyses of JNdi-1. 6. Measured 87Sr/86Sr of the NBS-987 standard = 0.712025 +/0.000023 (2 ). Blue highlighting represents OAE 2.

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106 Figure 4-31. Nd(0) from fossil fish teeth and Fe-Mn oxide coatings and residual fraction from ODP Site 1260 at Demerara Rise. Ages esti mated after Erbacher et al. (2004 and 2005). Figure 4-32. 87Sr/86Sr values from sequential extraction samples. Errors for Sr values are smaller than symbols. Seawater values fr om McArthur et al. (2001). Ages estimated after Erbacher et al. (2004 and 2005).

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107Table 4-10. REE values of Fe-Mn oxide coati ngs and residual frac tion normalized to PAAS from ODP Site 1260 at Demerara Rise. Samples La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Site 1260-coatings B 23 6W 130-132 0.110 0.091 0.0850.0850.0940.1140.1220.130 0.1510.1470.1660.1810.1830.179B 26 7W 10-12 6.508 9.187 11.95015.38021.53123.21523.53619.130 18.34814.61714.05211.88710.3999.737B 35 2W 120-121 0.289 0.148 0.2140.2800.3070.3940.4520.351 0.3790.4050.4490.4110.3870.451B 35 4W 103-104 3.524 2.984 5.0706.4678.72011.76910.7248.907 8.3226.6535.9024.7033.7053.244B 35 5W 46-47 0.050 0.018 0.0230.0270.0280.0390.0440.040 0.0500.0620.0810.0990.1260.164A 48 4W 10-12 0.051 0.029 0.0370.0460.0500.0630.0700.062 0.0730.0780.0930.0960.1060.123Site 1260-residual fraction B 23 6W 130-132 0.318 0.225 0.2340.2160.1950.8990.1770.155 0.1680.1550.1820.1980.2100.218B 26 7W 10-12 0.863 0.692 0.7070.6730.5960.5180.4960.424 0.4100.3690.4220.4710.5040.530B 35 2W 120-121 0.145 0.099 0.1110.1090.1040.1520.1010.091 0.0970.0970.1140.1250.1360.153B 35 4W 103-104 0.106 0.072 0.0820.0800.0750.1030.0790.065 0.0680.0640.0730.0790.0870.090B 35 5W 46-47 0.220 0.141 0.1690.1540.1380.1620.1370.122 0.1250.1230.1470.1720.1820.206A 48 4W 10-12 0.270 0.206 0.2080.2050.1840.1920.1770.133 0.1300.1230.1510.1740.1940.210 Samples normalized to initial weight and PAAS (Taylor and McLellen, 1985). Error is +/5%.

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108 Figure 4-33. Fe-Mn oxide coati ngs REE patterns from ODP Site 1260 at Demerara Rise. Samples are normalized to their initial weight and P AAS (Taylor and McLellen, 1985). Nod-A and Nod-P represent USGS Fe-Mn oxide coatings standards. Figure 4-34. Silicate residues REE patterns from ODP Site 1260 at Demerara Rise. Samples are normalized to their initial weight and PAAS (T aylor and McLellen, 1985).

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109Table 4-11. Major elements rations of Fe-Mn oxide coatings from Sites 367, 386, 550, 1049 and 1052. Sample Fe/Nd Mn/Nd Fe/Mn P/Nd Nd 1 Average Continental Crust 9.93 3.786.3E-0131.68N/AN/A4.4E+0287.55.0N/A Fe-Mn Nodules Nod-A* 0.07 0.100.01N/A0.023E-041160.61968.10.665.0 Nod-P* 0.08 0.060.01N/A6E-34E-03483.82427.50.216.8 Nod-A 0.07 0.099.9E-03N/A0.024E-041043.51766.40.655.3 Nod-P 0.07 0.057.4E-03N/A0.014E-04398.12012.10.214.4 Site 367 a17 1W 121-124 0.05 0.031.2E-041.210.042E-0541106.7584.270.41730.62.05 17 4W 32-35.5 0.04 0.031.6E-041.030.153E-0532980.184.6389.85057.3 18 1W 117-124 0.01 2E-033.1E-040.140.018E-06118502.60.6200184.01058 18 2W 71-73 0.57 0.112.6E-040.402.153E-03363.316.522.0815.80.11 19 4W 75-78 0.02 0.019.0E-050.370.081E-0588679.8N/AN/A7082.2 Site 386 38 3W 75-76.5 0.13 0.099.0E-050.780.528E-0488.61103.60.1617.6 41 5W 78-80 1.96 1.263.4E-030.1912.119E-0399.917.45.71420.3 43 2W 82-84 4E-03 2E-031.0E-050.420.013E-06351842.324855.614.22483.9 43 2W 122-123.5 4E-03 2E-033.0E-050.142E-032E-06583410.3856.9680.81263 43 2W 146-147.5 0.04 0.017.0E-050.190.065E-0519447.831.2623.61180.40.18 Site 550 8 2W 50-56 0.28 0.364.1E-040.011.115E-0211.29.61.223.1 10 1W 100-106 0.61 0.198.8E-040.431.778E-03112.813.98.1224.3 11 1W 50-56 0.19 0.221.7E-040.010.893E-0219.514.31.430.3 15 2W 20-26 0.59 0.191.3E-031.995.943E-03345.43.794.02072.8 17 2W 20-26 0.16 0.031.1E-041.080.681E-03619.850.312.3453.8

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110Table 4-11. Continued 24 1W 20-26 0.31 0.081.6E-040.811.333E-03312.715.719.9437.40.40 Site 1049A 10 2W 45-51 0.55 0.75.E-030.993.153E-058990.430744.70.31251520.15 13 1W 25-31 0.13 0.161.9E-041.280.402E-0670963.7521255.80.1238403 16 2W 50-56 0.52 0.22.7E-033.231.243E-03142.9176.00.8396.9 16 4W 62-68 1.93 1.063.5E-031.218.061E-0281.610.77.6744.6 20 1W 30-36 1.33 1.236.6E-030.1118.114E-012.10.37.243.6 20 5W 24-30 1.70 3.823.9E-030.09174E-012.50.38.547.0 21 2W 50-56 1.92 9.062.2E-030.0427.884E-011.81.01.975.6 Site 1052E 24R 2W 20-26 0.33 0.119.9E-040.811.073E-03312.62.5122.7338.6 28R 1W 100-106 0.10 0.355.6E-040.070.435E-03192.37.625.285.2 35R 2W 100-106 0.29 0.122.4E-031.362.404E-03237.11.3188.6571.9 36R 5W 20-26 0.02 1.943.2E-040.010.112E-03511.518.727.459.60.56 38R 1W 20-26 0.55 0.493.0E-030.654.073E-0238.90.2195.3159.30.57 41R 1W 10-16 0.05 0.572.3E-040.030.181E-03765.47.3104.3139.1 1. Nd represents Nd teethNd coatings. aindicates samples that fall within OAE 2. *USGS CRM, certified reference material va lues (Flanagan and Gottfried, 1980).

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111Table 4-12. Major elements rations of fish teeth/debris from Sites 549, 1050, 1052, 1260 and 1261. Sample Fe/Nd Mn/Nd P/Nd P/Fe Fe/Mn Ca/Nd 549 16R-2W 68-78 983.070.746.021.23797.31 132.454.881731.32 1050C 20R-4W 29-32 410.360.405.970.21153.71 25.7328.81376.47 1050C 21R-1W 42-43 397.470.761.790.1247.73 26.6515.42141.93 1052E 34R-4W 111-114 347.120.534.530.24211.02 46.6318.84693.93 1052E 38R-1W 20-26 138.330.960.960.0268.70 71.2839.81172.55 1052E 42R-2W 109-112 138.800.366.830.14113.14 16.5650.14371.66 1260A 49-1W 82-84 24.870.161.060.291326.79 1253.993.633184.79 1260A 49-2W 40-41 16.240.142.280.201017.99 446.8211.252398.36 1260A 49-3W 80-82 44.280.211.170.15523.89 446.968.031244.71 1260B 52-4W 130-132 25.030.521.670.21652.88 389.878.121576.69 1261B 5-4W 131-132 109.930.140.780.26144.83 185.182.95582.26 1261B 6-5W 5-7 69.531.012.620.14383.67 146.2118.73965.34

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112 CHAPTER 5 DISCUSSION Seawater Signal All the Nor th Atlantic sites that r ecovered sediment from OAE 2 record Nd values that increase to varying degrees in association with the changes in environmen tal and sedimentologic conditions. It is important to consider whether this isotopic shift docum ents changes in bottom water values as opposed to diagen etic alteration or the introducti on of unique materials related to conditions during OAE 2. Several lines of evid ence support the idea that the shifts in Nd do record changes in seawater Nd. First, specific lith ologies might be more susceptible to diagenetic alteration; however, the most dramatic Nd shift at Demerara Rise occurs within a continuous black shale section that spans the entire Cenomanian and Turo nian. In addition, there is no Nd shift associated with the major hiatus and the dramatic lithologic boundary between Cenomanian-Turonian black shales and ove rlying Late Campanian-Eocene chalks. Second, Blair (2006) demonstrated that Fe-Mn oxide coatings extracted were effective archives of deep sea Nd isotopes on Cenozoic to Cretaceous timescales. These extracted Fe-Mn oxide coatings and fossil fish teeth apatite yield the same Nd values above, within and below the OAE 2 excursion illustrating that two distinct pha se yield the same isotopic values (Table 4-2 and Figure 4-9). This implies th at either both phases are record ing original seawater or, less plausibly, that these two distinct phases were altered in such a way that the final products have the same value. In addition, the coherence between phases implies that both fossil fish teeth/debris and Fe-Mn oxide co atings are robust ar chives for Nd isotopes even under anoxic conditions. This is particularly noteworthy for the Fe-Mn oxides, which are redox sensitive. Furthermore, REE patterns and concentrati ons from fossil fish t eeth and Fe-Mn oxide coatings are similar pre-, synand post-OAE 2 (Figure 4-10), supporting the idea that measured

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113 Nd values during OAE 2 were not influenced by: 1) input of young volcanic material, which would have a HREE enrichment when normalize to PAAS (Rollinson, 1993) and 2) continental materials, which would have flat REE patte rns when normalized to PAAS (e.g., McLennan, 1989), as observed in the residue fractions in th is study (Figure 4-34). REE patterns of all the FeMn oxide samples are similar to those of USGS Fe-Mn nodule standards, revealing slight MREE enrichments when normalized to PAAS, which is the typical signature of REE fractionation into oxide coatings (Elderfield, et al., 1981; Bayon et al., 2002; Ha ley, 2004; Gutjahr et al., 2007). Experiments during this study illustrated that this oxide REE pattern dominates the residual fraction unless it is carefully and thoroughly removed with st rong acids. This observation suggests that the oxides are mo re likely to contaminate the residue, rather than the residue contaminating the extracted oxide fraction. Major element data also argue that the si gnal extracted from Fe-Mn oxides represents seawater rather than continental material. Majo r elements from Fe-Mn oxide coatings (Table 411) show variability between samples that could re present variable amounts of Fe and Mn in the coating or influence from clay and/or terrigen ous material which would be reflected by higher concentrations of Al, Ti and Si. (e.g., Dellw ig et al., 2000; Wehausen and Brumsack, 2002). However, Al to Fe+Mn, Ti to Fe+Mn and Si to Fe+Mn ratios of Fe-Mn oxide coatings are similar to those of the USGS Fe-Mn nodule st andards (Nod-A and Nod-P) and few order of magnitude lower than those of the average continental crust (Tay lor and McLennan, 1985) suggesting a non-crustal source and that no significant detrital c ontamination occurred during the leaching of the Fe-Mn oxide phase with HH. Phos phorus to Fe+Mn and P/Nd ratios are higher in Fe-Mn oxide coatings than in Nod-A and Nod-P suggesting extraction from apatite of some P and Nd during the leaching process. Fossil fish teeth/debris and extrac ted Fe-Mn oxides show

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114 similar REE patterns, thus unique identificati on of these two phases is difficult. However, inclusion of apatite in the Fe-M n oxide fraction would not affect this study since both phases record the same Nd isotopic values. Demerara Rise Very low Nd values across much of the Late Cretace ous set Demerara Rise apart from the rest of North Atlantic sites. Despite the range of upper to mid bathyal depths sampled, all three Demerara Rise sites (Sites 1258, 1260 and 1261) are characterized by exceptionally low Nd values ranging from -14 to -17.5 (Figures 5-1) These values are uniquely non-radiogenic for open ocean sites at this time when North Atla ntic values range from -3 (at Site 1052, Blake Nose) to -10 (at Site 367, Cape Verde), Central Pacific values range from -2.5 to -5.5 (Frank et al., 2005; Blair, 2006), and Tethys va lues range from -6 to -11.5 (Stille et al., 1990; Soudry et al., 2004; Pucat et al., 2005). Only two, very shallow s ites display similar non -radiogenic values: an Angolan site (~-16.9, Grandjean et al., 1987) and a Swedish site (-17, Pucat et al., 2005) (Figure 5-1). It is highly unlikely that Nd values at Demerara Rise are influenced by water masses originating at either of these sites, because none of the sites locat ed between Sweden and Demerara Rise record similar non-radiogenic values and the Angolan data precedes any estimates for the deep connection between the No rth and South Atlantic. One possible source of non-radiogenic Nd in the Demerara region is th e neighboring the Archean Guyana Shield (Blair, 2006). In fact, sediments from the Orinoco Rive r, which drains the Guyana Shield, yield nonradiogenic Nd values of -19.6 to -30.7 (Goldstein et al., 1997). Introduction of river-derived Nd into bottom wa ters on Demerara Rise implies that this fresh water source had to become dense enough to sink to intermediate depths. The Cenomanian is characterized by warm conditions that could lead to high evaporation in the tropical epicontinental basins surrounding Demerara Rise, that could result in the sinking of warm and

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115 saline surface water to in termediate or bottom water depths (Brass et al., 1982; Mosher et al., 2007) in a situation similar to modern Mediterranean outflow. Evidence for ventilation of deep waters in the tropical North Atlantic is provided by the lack of stratification of the water column observed in the Nd values for the depth transect at Demerara Rise. It is important to point out that the deepest site at Demerara is only at mid bathyal depths at the CTBI; thus, this warm, salin e water only needs to penetrate to intermediate depths. The intermediate water mass formed in this process, which has been referred as to the Demerara intermediate water (DIW) (MacLeod et al., submitted), is a predicted outcome of an Albian-Turonian ocean GCM. The model by Poul sen et al. (2001) indicates that significant downwelling occured off the northeastern coast of South America in the Late Cretaceous independent of the paleogeography or atmospheric CO2 concentrations. The fact that this water mass defined by very low Nd values is not observed outside the Demerara region suggests that the volume of water formed must have been relatively small; however, the continuous observation of non-radiogenic Nd values from the Albian to th e Maastrichtian in this region, with the exception of OAE 2 and the MCE, indi cates that local ventilation was a long term process. Ocean Anoxic Event 2 The correlation between the 6-8 Nd unit shift and the 6 13C shift during OAE 2 at all three Demerara Rise sites suggests that the ch anges in Nd isotopes are related to dramatic environmental changes associated with this ev ent. None of the othe r sites studied contain complete OAE 2 sections that are well defined by 13C data. Only the beginning of the event was recovered at Sites 367 at Cape Verde and 1050 at Blake Nose, and only the end of OAE 2 was recovered at Site 551 at Goban Spur (Huber et al., 1999; Gustaffson et al., 2003; MacLeod, unpublished data), while 13C data do not clearly identify an OAE 2 peak at Site 386 on

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116 Bermuda Rise. Based on these partial records, Nd values appear to shif t towards more radiogenic values during all of the defined OAE 2 events, with peak Nd values ranging from .4 to -5.0 at sites from the northern North Atlantic (Sites 386, 551 and 1050), and from 7.4 to -9.5 at tropical North Atlantic sites (Sites 367, 1258, 1260 a nd 1261) (Figures 5-1, 5-2 and 5-3B). Even though correlation betw een sites is difficult, th e fact that a positive Nd shift is recorded throughout the North Atlantic during OAE 2 implies that the cause of the shift is related to at least a basin-wide process. Therefore, possible causes incl ude a basin-wide disturbance in oceanographic circulation and/or introduction of Nd from an ex ternal source, such as the Caribbean Large Igneous Province (LIP) or a change in continental sources. Implication for the Cause of OAE 2 1. Continental sources One of the hypotheses to explain OAE 2 is a change in weathering inputs to the ocean during this interval that would increase the nutrient flux to the ocean, enhancing surface productivity, and thus leading to anoxia (J enkyns et al., 1980). Ne odymium isotopes argue against either a change in the intensity of weathe ring on the continents or a change in the types of rocks being weathered. First, a change in weathering would be expected to occur relatively slowly, yet the shift in Nd is quite rapid, estimate are that the initial increase in 13C took 120,000 to 150,000 years (Sageman et al., 2006). Second, it seems unlikely that Nd values would shift twice, once at the MCE (reco rded at Site 1260) and again th e OAE 2, and then return almost as rapidly to pre-excursion values. In addition, lo cal inputs that are believed to give DIW its distinct isotopic signature are non-radiogenic, thus, a positive Nd excursion would require a decrease in weathering intensity or inputs, which is difficult to reconcile with an enhanced hydrologic cycle predicted during OAE 2 (Calve rt and Pederson, 1990; Erbacher and Thurow, 1997).

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117 Moreover, Nd and Sr data from the residual fraction, extracted Fe-Mn oxide and fossil fish teeth/debris argue that the Nd shift observed in the latter two phases during OAE 2 is not influenced by a change in the composition of ro cks being weathered as recorded by the residual fraction. Neodymium isotopes of the residual fraction are 1.5 to 3 Nd units less radiogenic than fish teeth and Fe-Mn oxide coatings samples except for one sample younger than OAE 2 that may not have been fully cleaned (Figure 4-31). Also, the Nd values of the residue illustrate little variation before, during and after. The largest change observed in this fraction occurs in the sample that is much younger than OAE 2. Strontium isotopes of the residue are also distinct from Fe-Mn oxide coatings, which are similar to the Sr signal of seawater (Figure 4-32). The very radiogenic residue 87Sr/86Sr values again indicate that the residue is recording a more continental signal that is affected by OAE 2. Another way to produce the Nd shift observed at Demerara Ri se that could be related to continental weathering inputs would be to shut down DIW formation in response to increased freshwater input to the basin associated with the enhanced hydrologic cycle. Although this scenario provides an intriguing explanation for the shift recorded at Demerara Rise, it cannot explain the shifts observed at othe r North Atlantic sites. Thus, even if this process contributed to the magnitude of the shift of Demerara Rise, another process is requi red to account for the positive shift observed basin-wide during OAE 2. 2. Caribbean large igneous province The eruption of the Caribbean LIP has been da ted within a range of 87 to 95 Ma (Alvarado et al., 1997 ; Sinton et al., 1998; Hauff et al., 2000). Recently, Snow et al. (2005) calculated a more accurate age of 93.46 0.38 Ma for the beginning of the eruption using 40Ar/39Ar techniques, which correlates well with the CenomanianTuronian boundary. The volcanic activity would have then continued until ~87 Ma (Snow et al., 2005). Several authors have

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118 argued that hydrothermal circula tion related to this emplaceme nt would introduce fertilizing trace metals to surface water (S inton and Duncan, 1997; Kerr, 1998; Snow et al., 2005), and thus potentially releasing radiogenic Nd into the ocea n. Therefore, the positive Nd shifts observed at North Atlantic sites could reflect hydrothermal inputs, characterized by Nd value ~+10 (oceanic basalts). Nd released by hydrothe rmal vents in todays ocean is removed quantitatively by oxide formation at the ridge (e. g. Halliday et al ., 1992; Sinton and Duncan, 1997). However, under anoxic conditions, radiogenic Nd might be transported farther away. In fact, many other elemental abundance anomalies are recorded during OAE 2 in the WIS (Orth and al., 1993, Snow et al., 2005). These anomalies likely orig inate from intense s eafloor spreading and hydrothermal activity in the Pacific and Caribbean corridor as they are la rger in the west and decrease toward the east, suggesting a west to east circulation patte rn that connects the Caribbean LIP in the equatorial eastern Pacific with North Atlantic sites. In this scenario, we would expect to see a si milar Nd shift at western North Atlantic sites (Blake Nose, Bermuda Rise and Demerara Rise) a nd a smaller Nd shift at eastern North Atlantic sites (Goban Spur and Cape Verde). The obser ved Nd shifts record ed throughout the North Atlantic does not appear to follow this pattern (F igure 5-2); however, this may reflect the fact that most of the sites do not contain complete OAE 2 records. Moreover, this scenario requires development of deep ocean anoxia prior to transm ission of the Nd signal, which implies that the 13C excursion should lead the Nd excursion. Higher resolution records at the onset of the excursion are required to thor oughly evaluate this situation, but based on current data at Demerara Rise it appears that either th e two records increase at the same time or Nd slightly leads 13C (Figure 4-8). The shift recorded at Demera ra Rise also implies that enhanced mixing between the Demerara Rise and the rest of the North Atlantic is required in addition to input

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119 from the LIP source. Otherwise Demerara Rise would continue to be dominated by the nonradiogenic signal of the DIW. The LIP hypothesis cannot be discounted for th e cause of OAE 2 wit hout additional data. If this hypothesis is valid, Nd data from the WIS (Pueblo, Colorado) should display a strong radiogenic Nd excursion because this region records strong trace metal signals (Orth et al., 1993; Snow et al., 2005). In addition, Pacific sites, such as Shatsky Rise (north west Pacific) might be expected to record an excursi on because of their pr oximity to the Caribb ean LIPs. Moreover, it would be interesting to evaluate whether trace meta l abundance pattern vary at Demerara Rise as they do in the WIS and whether they record the same pattern of two peaks seen with Nd. 3. Oceanic circulation Alterna tively, shifts in Nd can be interpreted in terms of ch anges in circulation. In this case it is assumed that values of the end member wa ter masses did not change in response to altered Nd inputs to the ocean. Time slice maps before, during and after OAE 2 illustrate potential changes in ocean circulation patterns associated with this event. Before OAE 2, Nd values in most of the North Atlantic are similar to repo rted Tethyan values (Figures 5-1 and 5-3A), suggesting dominant east to west interm ediate/deep water flow. In contrast, Nd values of northern and northeastern North Atlantic intermedia te to deep sites (Bla ke Nose, Bermuda Rise and Goban Spur) increase to ~-5 at OAE 2, whil e the deeper tropical sites (Demerara Rise and Cape Verde) have values of ~-7.5 (Figure 5-2). This distribution is compatible with clockwise circulation of Pacific-sourced water through the basin that mixes with some Tethyan outflow prior to arriving in the tropical region (Fig. 5-3B). This tran sition could be caused by weaker production of intermediate to deep warm, saline water derived from the Tethys Ocean, possibly in association with the enhanced hydrologic cycle (Calvert and Pederson, 1990; Erbacher and Thurow, 1997), or by enhanced invasion of the P acific water mass into the North Atlantic.

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120 The fact that all three Demerara Rise site s record similar excu rsions during OAE 2 indicates that the water column was well mixe d for mid to upper bathyal paleodepths before, during and after OAE 2 at this location. OAE 2 also represents the only time slice with similar values throughout the tropical At lantic at both Demerara Rise a nd Cape Verde. A decrease in 18O values of benthic foraminifers at the base of OAE 2 indicates that bottom water salinity decreased and/or that bottom wa ter temperatures increased (Fri edrich et al., 2006). Increased precipitation associated with an accelerated hydrological cycle at the CTBI could have enhanced freshwater runoff, thereby leading to a partial or even total shutdown of the DIW (Friedrich et al., 2006, Mosher et al., 2007). As a result, North Atlantic water with a more radiogenic signal would have replaced DIW at Demerara Rise during OAE 2. Several authors have proposed that OAE 2 is related to the initial deep water connection between the North and South Atlantic Ocean basins th at resulted in an abr upt change in Atlantic deep water circulation (Tucholke and Vogt 1979; Summerhayes, 1981; Wagner and Pletsch, 1999; Poulsen et al, 2001, 2003; Pletsch et al., 2001; Kuypers et al., 2002), although the timing of this deep connection is sti ll controversial with estimates ranging from the late Cenomanian to Maastrichtian (MacLeod and Huber, 1996; Frank and Arthur, 1999; Frank et al., 2005, Friedrich and Erbacher, 2006). As several au thors pointed out, the injection intermediate or deep water from the South Atlantic into th e North Atlantic following the openi ng of the equatorial Atlantic gateway could create favorable conditions for vertical advection of nutrients, widespread productivity, expansion of the minimum oxygen zone and the accumulation of organic matter (Tucholke and Vogt, 1979; Leckie et al., 2002). This connection could also account for the positive shift in Nd through the introduction of South Atlantic water. GCM simulations (Poulsen et al.; 2001, 2003) for the CTBI i ndicate that deepening of the Equatorial Atlantic Gateway

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121 (EAG) initiated vigorous circul ation between the North and the South Atlantic, which led to freshening at depths in the No rth Atlantic consistent with observations at Demerara Rise (Friedrich et al., 2006). According to the model North Atlantic deep circulation transits from anticyclonic (counterclockwise) to well-developed cyclonic gyre that circulates through the North and South Atlantic basins at the opening of the gateway. Neodymium data can be correlated to the model with Albian-late Cenom anian anticyclonic circulation, introducing water from the Tethys (Figure 5-3A), followed by the initiation of a cyclonic gyre during OAE 2 that redistributes Pacific-sourced wate rs (Figure 5-3B). These Pacific waters could be mixed with less radiogenic Tethys or South A tlantic derived deep water masses in the tropical North Atlantic leading to increased Nd values at Cape Ve rde and Demerara Rise There are no published Nd data for the South Atlantic in th e Late Cretaceous. In fact, the oldest South Atlantic data come from the late Paleocene when Nd values for the South Atlantic ranged from to (Thomas et al., 2003). Assu ming that this water was sourced from the Southern Ocean and that this source did not ch ange between the Late Cretaceous and Early Cenozoic, the upper end of the South Atlantic rang e is identical to estimates of Tethys waters (Pucat et al., 2005; Soudry et al., 2006). Ca pe Verde and Demerara Rise both record Nd values of -7.5 at the CTBI, which could represent a mixtur e of Pacific water with either Tethys water or South Atlantic water at -9. The role of EAG in the formation of OAE 2 cannot be tested without Late Cretaceous Nd values from the South Atlantic, such as ODP Sites 511 and 530. Even with these data, the Nd values may be too similar to Tethys sourced waters to differentiate between source regions.

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122 Late Cretaceous North Atlantic Circulation Late Aptian-Cenomanian From the Albian to Cenomanian, it appears that the western North Atlantic is fed by a main water mass with Nd values ranging from -8 to -9 (Figures 5-1 and 5-3A). This water mass is recorded at Goban Spur (Sites 549, 550 and 551) and Cape Verde (Site 367). The Tethys Ocean has Nd values of ~-9 for shallow sites for the same interval of time (Pucat et al., 2005). GCMS of oceanic circulation for the Late Cretaceous in dicate that warm, saline intermediate to deep water likely formed in subtropical regions of excessive evaporation in the eastern Tethys at this interval of time, much like the Mediterranean in the modern Nort h Atlantic (Brass et al., 1982; Arthur et al., 1985, 1987; Barron and Peterson, 1990; Barron et al;, 1993; Bice and Marotzke, 2001; Poulsen et al., 2001, 2003). Nowadays, the Medi terranean outflow into the North Atlantic is the warmest and densest intermediate water mass formed in the oceans (Hay et al., 1993). Similar Nd values recorded at shallow sites in the Tethys (Pucat et al., 2005; Soudry et al., 2006) and intermediate to lower ba thyal depths in the North Atlan tic also suggest that warm and saline waters formed in the Tethys (Tethys Botto m Water, TBW) flowed westward in the North Atlantic (Figure 5-3A). At the same time, Bermuda Rise (Site 386) has Nd values ranging from 7.5 and -6.5, slightly more radiogenic than deep ea stern North Atlantic site s but also slightly less radiogenic than the deepest site at Blake Nose (-5 to .5, Site 1049) which had values similar to the Pacific (Figure 5-1). This indicates that the western North Atlantic (Bermuda Rise and Blake Nose) may have recorded a deep water mass that was a mixture of less radiogenic Tethys and more radiogenic Pacific waters (Figure 5-3A ). In contrast, throughout this time interval, Demerara Rise sites maintain their unique non-radiogenic Nd values (~-16), consistent with a locally derived intermediate/deep source that dominated in the Demerara region, but did not extend to Cape Verde to the east or Blake Nose to the north.

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123 Unlike Demerara Rise, the late Aptian to Cenomanian Nd data at Blake Nose (Sites 1049, 1050 and 1052) suggest a stratified wa ter column. This stratification could be due to eolian input of volcanic ash at the surface or the presence of different water masses at different depths. Volcanism in the Late Cretaceous was widespre ad in the Gulf of Mexico (Byerly, 1991). The closest volcanic activity to Blake Nose was lo cated in the Mississippi Embayment and thus, volcanic material may have been introduced to this region. As a re sult, a gradient in Nd values could have developed that w ould be comparable to the modern Pacific Ocean in which radiogenic Nd values are recorded at the surface with decreasing values at depth due to seawater particle exchange (Goldstein and Hemming, 2003). This mode l suggests relatively sluggish circulation (Poulsen et al., 1999; Kuypers et al., 2002) and limite d ventilation of intermediate waters in the western North Atla ntic from the Albian to Cenoma nian. The other option would be shallow Pacific-sourced waters to overlie a bot tom water mass sourced from the Tethys. This scenario implies more vigorous mixing within the basin. The fact that ash c oncentrations at Sites 1050 and 1052 do not change as Nd values change (Norris et al., 1998) argues that the stratification is related to layers with distinct Nd values and more vigorou s circulation patterns. From ~103 to 95 Ma (late Albian to early Cenomanian), Nd values at the shallow site (Site 1052) progressively decrease towards values record ed at the intermediate site (Site 1050) and they appear to almost merge from ~100.4 to 99.6 and again at ~95 Ma, suggesting a reduced vertical stratification between the two sites which represents depths of ~500 and 1500 m (Petrizzo et al., 2008). This collap se of upper-ocean stra tification as been proposed as cause of the late Albian OAE 1d (~99 Ma) based on the 18O record at Site 1052 (Wilson and Norris, 2001; Petrizzo et al., 2008).

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124 Turonian The return to less radiogenic Nd values after the OAE 2 event (-9 at Cape Verde; -6.5 to 8.2 at Goban Spur; -6.8 at Bermuda Rise and -6 at Blake Nose) (Figures 5-1 and 5-3C) can be explained by continued opening of the Equatorial Atlantic Gateway and the resulting increased flow of South Atlantic deep water into the North Atlantic basin (Poulsen et al, 2001, 2003; Pletsch et al., 2001; Friedrich et al., 2007) or by re-establishmen t of Tethys warm, saline deep water formation. Compilation of 18O data (Figure 2-2) indicate s that both North and South Atlantic deep waters started to progressively cool in the late Tu ronian (Friedrich et al., 2007), suggesting that Tethys-derived warm, saline deep water was no t the major water mass in the North Atlantic for this interval of time. A lthough Nd isotopes cannot distinguish between South Atlantic and Tethyan waters, the 18O data suggest that the decrease in Nd(t) records increase South Atlantic water flow and thus the opening of the EAG. Coniacian-Santonian Goban Spur and the western Tethys (Pucat et al., 2006) record Nd values of ~-10.2 to 11.2 in the Santonian that appear too low to repr esent South Atlantic or Tethys-derived waters (Figures 5-1). Pucat et al. (2006) proposed th at these non-radiogenic waters represented the initiation of non-radiogenic deep water formation in the northern North Atlantic. Unfortunately, this interval of time is represen ted by a hiatus at most of th e study sites (Bermuda Rise, Blake Nose, Demerara Rise and Cape Verde), which Wa gner and Pletsch (1999) attributed to erosive deep water currents due to the recent deep c onnection between the Nort h and South Atlantic. Campanian-Maastrichtian The shif t towards less radiogeni c values at Blake Nose in the Campanian could indicate restriction of the connection to the Pacific, possibly due to te ctonic changes in the Caribbean region (Pindell et al., 2006). By this time, all of the sites in the North Atlantic, with the exception

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125 of Demerara Rise, record values of ~-8.5 (Figure 5-1) indicating homogenized deep water within the North Atlantic basin. While Demerara returned yet again to pr oduction of a local water mass, the rest of the basin records valu es that would be expected due to inflow of deep South Atlantic waters, which is reasonable given that all models support a fu lly open Equatorial Atlantic Gateway at this time (Frank and Arthur, 1999; Fr iedrich et al., 2006, 2007). Benthic foraminifera 18O values are similar in the North and South A tlantic (Figure 2-2) (H uber et al., 2002) during the Campanian, also supporting the idea of a fully opened EAG and deep water connection between the two oceanic basins (Friedrich et al., 2007). For the first time since OAE 2, Demerara Rise Nd isotopic values at the only site analyzed for this young interval (Site 1258) increase rapidly toward more radiogenic Nd values of ~-11 in the mid to late Maastrichtian, but they remain lo wer than those observed at other North Atlantic sites for the same interval of time. Values at Bermuda Rise do start to approach similar Nd values; however, the age model at Bermuda Rise is poorly constr ained, therefore the age of the decrease observed at Site 386 is not well known. This Nd shift at Demerara Rise from unique non-radiogenic background values to more Atlanticlike values in the mid to late Maastrichtian suggests the end of conditions necessary for form ation of the DIW. The Latest Cretaceous is associated with a global cooling trend; as a resu lt, evaporation rates and water temperatures may have decreased to the po int that warm, saline intermediate water could not form any longer.

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126 Figure 5-1. Compilation of Nd(t) values across the Late Cretaceous in the North Atlantic, Pacific and Tethys. Ages for Sites 367, 386 and 511 ar e estimated after biostratigraphic data from Shipboard Scientific Party (1975, 1975 and 1985 respectively).

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127 Figure 5-2. Pre-OAE 2 Nd values and maximum values reached during OAE 2 at ODP Sites 367, 386, 551, 1050, 1258, 1260 and 1261.

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128 Figure 5-3A. Albian to Cenomanian paleogeogra phic map of the North Atlantic (Lawver et al., 2002). represents shallow ODP Sites, represents intermediate ODP Sites and represents deep ODP Sites. Values represent Nd(t) with color corresponding to the depth of the site. DIW = Demerara interm ediate water; PWM = Pacific Water Mass; TWM = Tethys Water Mass. Arrows represent intermediate and deep circulation pathways.

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129 Figure 5-3B. Cenomanian-Turonian Boundary In terval paleogeographic map of the North Atlantic (from Kuypers et al., 2002). represents shallow ODP Sites, represents intermediate ODP Sites and represents deep ODP Sites. Values represent OAE 2 peak Nd(t) with color corresponding to the de pth of the site. DIW = Demerara intermediate water; PWM = Pacific Water Mass; SAWM = South Atlantic Water Mass; TWM = Tethys Water Mass. Arrows represent intermediate and deep circulation pathways. Incursion of water masses into the Western Interior Seaway after Orth (1993), Leck ie et al. (1998).

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130 Figure 5-3C. Turonian paleogeographic map of the North Atlantic (from Kuypers et al., 2002). represents shallow ODP Sites, represents intermediate ODP Sites and represents deep ODP Sites. Values represent Nd(t) with color corresponding to the depth of the site. DIW = Demerara interm ediate water; PWM = Pacific Water Mass; SAWM = South Atlantic Water Mass; TWM = Tethys Water Mass. Arrows represent intermediate and deep circulation pathways.

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131 Figure 5-3D. Campanian-Maastrichtian paleogeog raphic map of the North Atlantic (Lawver et al., 2002). represents shallow ODP Sites, represents intermediate ODP Sites and represents deep ODP Sites. Values represent Nd(t) with color corresponding to the depth of the site. DIW = Demerara interm ediate water; SAWM = South Atlantic Water Mass and PWM = Pacific Water Mass. Arrows represent intermediate and deep circulation pathways.

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132 CHAPTER 6 CONCLUSIONS Neodym ium isotopic values were analyzed on fo ssil fish teeth/debris and extracted Fe-Mn oxide coatings from depth transects at Blake No se, Demerara Rise and Goban Spur, as well as two deep sites located on Bermuda Rise and Cape Verde located in northern to the equatorial North Atlantic Ocean basin. Several lin es of evidence support the idea that Nd values recorded in fossil fish teeth/debris and Fe-Mn oxides represent seawater rather than later diagenetic alteration or contamination: 1) the major change of lithol ogy at Demerara Rise from Cenomanian-Turonian black shales to Late Campanian-Eocene chalks is not associated with the Nd shift, 2) fossil fish teeth/debris and extracted Fe-M n oxides yield the same Nd ratios before, during and after OAE 2, and 3) Nd and Sr isotopic values of the re sidual fraction remain re latively constant across OAE 2. Neodymium chemical extracted from Fe-M n oxides could reflect Nd contained in the bulk sediment rather than purely in Fe-Mn oxide coatings. However, data from this study provide evidence that the signal extracted from Fe-Mn oxi des represents the oxid es: 1) REE patterns of extracted Fe-Mn oxides are typical of Fe-Mn oxide coatings and differ from shale REE patterns, 2) major elements extracted from Fe-Mn oxide s are similar to USGS Fe-Mn nodule standards rather than continental material. Thus, fossil fish teeth/debris and extrac ted Fe-Mn oxide coatings both appear to be robust archives for seaw ater Nd isotopes even under anoxic conditions. Throughout most of the Late Cretaceous, sites at Demerara Rise record non-radiogenic Nd values from shallow to bathyal depths with va lues ranging from -14 to -17.5. These values are unique for the North Atlantic region. The most likel y source is local input of very non-radiogenic continental material, probably from the Guyana Sh ield, that was carried to the ocean by rivers. Transmission of this surface signal to intermed iate depths requires excess evaporation and formation of a local warm, saline intermediate water referred to as the Demerara intermediate

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133 water. The lack of stratificati on between the three sites provides support for local ventilation and indicates that there was insufficient North A tlantic circulation to homogenize bottom waters. All North Atlantic sites that contain an OAE 2 section defined by a positive 13C excursion display a positive Nd shift that varies in size with the completeness of the record. Demerara Rise contains the most complete sectio ns and records an increase of ~8 Nd units. Peak values are similar to Late Cretaceous Nd values observed elsewhere in th e North Atlantic and the Tethys (Pucat et al., 2005; Soudry et al., 2004). The magnitude of the positive Nd excursion at the other sites ranges from ~1 to 3 Nd units. The correlation between 13C and Nd excursions implies that both proxies are r ecording conditions fundamental to the formation of OAE 2. The widespread distribution of Nd shift implies that o ceanic changes associated with the shift were basin-wide. Three possible interpretations of the Nd data were evaluated: 1) a change in Nd input from the continents; 2) hydrothermal input of Nd associated with the formation of the Caribbean LIP; and 3) reorganization of basi n-wide deep ocean circulation. The first hypothesis would requ ire less input from the continent during OAE 2, which is inconsistent with models of an accelerated hyd rological cycle during th e thermal maximum. It would also require very rapid short term ch anges in continental w eathering. The positive Nd shifts observed at OAE 2 could be attributed to Nd sourced from the Caribbean LIP; however, the timing of this event has not been exactly co nstrained to the timing of the OAE 2. Moreover, this sceanario would require development of anoxia, as recorded by 13C, prior to transmission of the Nd signal. Higher resolution records are necessary to test this lead/lag relationship, but initial results indicate that the records shift simultaneously or that Nd leads slightly. Finally, a major change in water mass circulation in the North At lantic could have aff ected the entire water column, accounting for the 13C shift (surface process) and Nd isotopes (deep process). This

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134 change could have been caused by enhanced circul ation with Pacific deep water associated with the opening of the EAG separating the Nort h and South Atlantic Ocean basins. The Nd peak at Demerara also suggests a brief mixing or a repla cement of the DIW with water from the larger North Atlantic circulat ion system during the Nd peak at OAE 2, possibly due to the freshening of surface water. Thus, this model suggests that enhanced circulation, rather than stagnation accompanied the event. Additional evaluation of the LIP and of the circulation models is required. This could include additi onal Nd isotopic analyses in the Pacific and in the WIS, as well as trace metal analyses at Demerara Rise in order to further test the role of the Caribbean LIP in the formation of OAE 2. Neodymium values from deep South Atlantic sites are needed to evaluate the opening of the EAG and its relationship to OAE 2, assuming that Nd values of the South Atlantic can be distingui shed from those of the Tethys. General Late Cretaceous circulation patterns based on Nd data indicate that the Tethys Seaway or the South Atlantic were the major sources of deep water for most of this interval with a small contribution from the Pacific. From the Albian to late Cenomanian, the North Atlantic was fed by a main water mass with Nd values similar to those of the Tethys Ocean, indicating sinking of warm, saline Tethys-derived water into the North Atlantic. The mixing zone between Tethys and Pacific deep waters was located in the western boundary of the North Atlantic. The deep opening of the EAG between the North and S outh Atlantic appears to start in the TuronianConiacian causing the reorganization of oceanic circulation in both basins. By the Campanian, the EAG was fully open and North Atlantic Nd values indicate basinwide homogenization of the deep waters probably sourced from the South Atlantic with restricted influence of Pacific water.

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135 LIST OF REFERENCES Aboucha mi, W., Goldstein, S.L., Galer, S.J.G., Eisenhauer, A., and Mangini, A., 1997, Secular changes of lead and neodymium in central Pacific seawater recorded by a Fe-Mn crust: Geochimic et Cosmochimica Acta, v. 61, p. 3957-3974. Albarede, F., and Goldstein, S.L., 1992, A world map of Nd isotopes in seafloor ferromanganese deposits: Geology, v. 20, p. 761-763. Albarede, F., Goldstein, S.L., and Dautel, D., 1997, 143Nd/144Nd of Mn nodules from the Southern and Indian oceans, the global oceanic Nd budget, and their bearing on the deep ocean circulation during the Quarternary: Geochim. Cosmochim. Acta, v. 61, p. 12771291. Alvarado, G.E., Denyer, P., and Sinton, C.W., 199 7, The 89 Ma Tortugal komatiitic suite, Costa Rica; implications for a common geological or igin of the Caribbean and eastern Pacific region from a mantle plume: Geology (Boulder), v. 25, p. 439-442. Arthur, M.A., Dean, W.E., and Pratt, L.M., 1988, Ge ochemical and climatic effects of increased marine organic carbon burial at the Cenomanian/Turoni an boundary: Nature, v. 335, p. 714-717. Arthur, M.A., Dean, W.E., and Schlanger, S.O ., 1985, Variations in the global carbon cycle during the Cretaceous related to climate, vol canism, and changes in atmospheric CO (sub 2): Geophysical Monograph, v. 32, p. 504-529. Arthur, M.A., Jenkyns, H.C., Brumsack, H ., and Schlanger, S.O., 1990, Stratigraphy, geochemistry, and paleoceanography of organic-carbon-rich Cretaceous sequences, 75-119 p. Arthur, M.A., Schlanger, S.O., and Jenkyns, H.C., 1987, The Cenomanian-Turonian oceanic anoxic event, II. Paleoceanogrpahic c ontrols on organis-matter production and preservation: Geological Society of London, Special Publication, v. 26, p. 401-420. Axelsson, M.D., Rodushkin, I., Ingri, J., and h lander, B., 2002, Multielemental analysis of MnFe nodules by ICP-MS: optimization of an alytical method: The Analyst, v. 127. Barrera, E., and Savin, S.M., 1999, Evolution of la te Campanian-Maastrichtian marine climates and oceans: Boulder, CO, United States, Geological Society of America. Barron, E.J., and Peterson, W.H ., 1990, Mid-Cretaceous Ocean Circ ulation: Results from model sensitivity studies: Palaeoceanography, v. 5, p. 319-337. Barron, E.J., Peterson, W.H., Thompson, S., and Po llard, D., 1993, Past clim ate and the role of ocean heat transport: Model simulations for the Cretaceous: Paleoceanography, v. 8, p. 785-798.

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147 BIOGRAPHICAL SKETCH Elodie Bourbon was born in Brianon in the Ha utes Alpes, France. Her prim ary education, elementary through high-school, was completed in Brianon, France. She became interested in geology after taking the geology course taught by Raymond Cirio her first year of high school. He made her discover the geology of the Alps through field trips around Br ianon and to Corsica for a week. She knew that when it was time to go to college she would study geology and become as passionate as he was. She started the bachelor degree of Sciences de la Terre, de lUnivers et de lEnvironement at the Universi t Joseph Fourier in Grenoble, France, which has an excellent geology program and was still locate d in the Alps. Her second year, she applied to the exchange program of the University and went to complete her last year of the bachelors degree at the University of Fl orida. At UF, her research fo cused on Late Cretaceous oceanic circulation in the North Atlantic using Nd isot opes, under the guidance of Dr. Ellen Martin. After completion of the Master of Science degree, Elodie plans on working for an environmental consulting firm in New York and eventually goe s back to school for a PhD. in a few years.