A Detrital Zircon Transect across the Son Valley Sector of the Vindhyan Basin, India

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Title:
A Detrital Zircon Transect across the Son Valley Sector of the Vindhyan Basin, India Constraints for Basin Evolution and Paleogeographic Implications from U-Pb and Hf Isotopic Data
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english
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Turner, Candler Coyle
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University of Florida
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Degree:
Master's ( M.S.)
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University of Florida
Degree Disciplines:
Geology, Geological Sciences
Committee Chair:
Meert, Joseph G
Committee Members:
Mueller, Paul A
Kamenov, George

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Subjects / Keywords:
detrital -- geochronology -- india -- marwar -- precambrian -- purana -- vindhyan -- zircon
Geological Sciences -- Dissertations, Academic -- UF
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Geology thesis, M.S.
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theses   ( marcgt )
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Abstract:
The Vindhyan Supergroup, located in central peninsular India, is one of the largest and thickest Precambrian sedimentary successions of the world, outcropping over an area of over 104,000 km2.  The Vindhyan is the largest of the so-called“Purana” basins in India.Split into the upper Vindhyan and the lower Vindhyan, the age of the Upper Vindhyan sedimentary sequence is the subject of considerable controversy. This study seeks to determine if the Vindhyan Basin is much older in age than a previously assigned Neoproterozoic age, the age of basin closure, source of sediments, and to discuss the nearby “Trans-Aravalli Vindhyans,” or Marwar basin, and its relationship to the Vindhyan Basin.Multiple hypotheses have been forwarded concerning basin closure: some argue for an early Neoproterozoic to late Mesoproterozoic closure (~1050 Ma) of Upper Vindhyan sedimentation whereas others argue for an Ediacaran-Cambrian age.  U-Pb dating of detrital zircons from upper Vindhyan sedimentary rocks of the Son Valley sector, purported U-Pb detrital zircon from the Rajasthan sector of the basin and paleomagnetic data from the Majhgawan kimberlite indicates a Mesoproterozoic age for the upper Vindhyans and supports the hypothesis that the Vindhyan and Marwar basin do not share a co-evolutionary history. However,Hf isotopic data show that the Vindhyan and Marwar shared similar sources, most likely from the Aravalli region. U-Pb data corroborates other provenances that provided detritus to the Vindhyan and Marwar basins. Paleographical implications can also be made from these detrital zircon age populations.
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In the series University of Florida Digital Collections.
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Includes vita.
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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.
Thesis:
Thesis (M.S.)--University of Florida, 2012.
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Adviser: Meert, Joseph G.
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RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2013-06-30
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by Candler Coyle Turner.

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1 A DETRITAL ZIRCON TRANSECT ACROSS THE SON VALLEY SECTOR OF THE VINDHYAN BASIN, INDIA: CONSTRAINTS FOR BASIN EVOLUTION AND PALEOGEOGRAPHIC IMPLICATIONS FROM U Pb AND Hf ISOTOPIC DATA By CANDLER COYLE TURNER A THESIS PRESEN TED 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 2012

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2 2012 Candler Turner

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3 To my folks my friends, the Earth, and India

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4 ACKNOWLEDGEMENTS First and foremost I thank my parents for their never ending support. I thank my allknowing advisor Dr. Joseph Meert for his patience and support during my career at the University of Florida and for extending me all the wonderful opportunities that I have received along the way. I also thank the many profess ors that have helped to expand my knowledge in G eology. I also thank Dr. Matt Smith for helping to make my life as a teaching assistant much easier. I must thank NSF for their funding of this research. Last but not least, I thank the many friends that I have gained during my tenure at the University of Florida for making it quite a fun ride. Finally, I thank mother Earth, for without her, none of this would have been possible.

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5 TABLE OF CONTENTS page ACKNOWLEDGEMENT S ............................................................................................... 4 LIST OF TABLES ............................................................................................................ 6 LIST OF FIGURES .......................................................................................................... 7 LIST OF ABBREVIATIONS ............................................................................................. 9 ABSTRACT ................................................................................................................... 10 CHAPTER 1 INTRODUCTION .................................................................................................... 12 Geologic Setting ..................................................................................................... 16 Vindhyan Basin ................................................................................................ 16 Lower Vindhyan Sequence ............................................................................... 17 Upper Vindhyan Sequence ............................................................................... 18 Marwar Basin ................................................................................................... 19 Summary ................................................................................................................ 20 2 GEOCHRONOLOGY METHODS ........................................................................... 26 3 RESULTS ............................................................................................................... 29 U Pb Geochronology .............................................................................................. 29 Vindhyan Samples .................................................................................................. 29 Marwar Samples ..................................................................................................... 30 Hf Isotopes .............................................................................................................. 32 4 DISCUSSION ......................................................................................................... 67 Marwar and Vindhyan Correlations ......................................................................... 67 Provenance of Detrital Zircons from the Marwar and Vindhyan Basins .................. 71 Vindhyan Provenance ...................................................................................... 73 Marwar Provenance ......................................................................................... 77 Paleogeographic Implications ................................................................................. 78 Links between Continental Landmasses from Detrital Zircon Records ............ 78 Rodinia and Gondwana .................................................................................... 78 5 CONCLUSIONS ..................................................................................................... 90 LIST OF REFERENCES ............................................................................................... 92 BIOGRAPHICAL SKETCH .......................................................................................... 103

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6 LIST OF TABLES Table page 3 1 Upper Vindhyan U Pb Isotopic Data .................................................................. 34 3 2 Marwar U Pb Isotopic Data ................................................................................ 50 3 3 Hf Isotopic Data ................................................................................................. 61

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7 LIST OF FIGURES Figure page 1 1 Map of continental India and the locations of Purana basins, distribution of cratons, and tectonic domains (modified from Rao and Reddy 2002). Important Abbreviations: ..................................................................................... 22 1 2 Geologic Map of the Vindhyan Basin. A) Map of continental India; B) Rajasthan Sector; C) Son Valley Sector ; D) Bundelkhand Sector. The NarmadaSon Lineament creates the eastern most boundary of the Vindhyan 23 1 3 Correlations and Stratigraphy of the Vindhyan Supergroup from both the Son Valley and Rajasthan Sectors. Age constraints provided from Gregory et al. (2006), Sarangi et al. (2004), Ray et al. (2003, 2002), De (2006), and Malone .. 24 1 4 Marwar Stratigraphy and correlations to t he Salt Range of Pakistan, the Krol Tal belt of the Himalayas, and the Huqf Supergroup of Oman. Note that the Krol Tal and Huqf Supergroup contain stratigraphy from the Marinoan time ...... 25 3 1 De trital zircon probability plots for the select samples from the Son Valley (Kaimur, Rewa/Kaimur, Rewa and Bhander Sandstone) Sector and Rajasthan. .......................................................................................................... 64 3 2 Detrital Zircon probability plots for select samples from the Marwar Supergroup. Note the appearance of <1000 Ma zircons in these plots compared to upper Vindhyan plots that contain no zircons <1000 Ma ............... 65 3 3 Pb age data for ~1.71.8 Ga detrital zircons from both the Marwar and upper Vindhyan sediments. The majority of samples contain negative ................. 66 4 1 Cumulative UPb age Probability Density Plots for Marwar and upper Vindhyan Detrital zircons. Red shaded area represents zircons dated to <1000 Ma.. ......................................................................................................... 84 4 2 Paleomagnetic pole positions at ~1.01.1 Ga from Venkateshwarlu and Chalapathi Rao (in press) kimberlite and lamporite intrusions in the Dharwar craton, Majhgawan kimberlite, ............................................................................ 85 4 3 Geodynamic Map of the supercontinent Rodinia reconstruction from Li et al. ( 2008) ................................................................................................................ 86 4 4 Generalized Gondwana reconstruction depicting Neoproterozoic and younger orogenic belts that separate the various cratons of West and East Gondwana (Malone et al. 2008; modified from Gray et al. 2007). ...................... 87

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8 4 5 Locations of Ediacaran Cambrian Basins in the ArabianNubian Shield, Himalayas, Pakistan and Madagascar that correlate with the Marwar Basin as seen in the traditional Gondwana reconstruction. ........................................ 88 4 6 Detrital zircon spectra representing the phases of orogenesis advocated by Runcorn (1 962) from data publi shed in Hawkesworth et al. (2009). Supercontinents represented .............................................................................. 89

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9 LIST OF ABBREVIATIONS AFB Aravalli Delhi Fold Belt BPMP Bhavani Palghat Mobile Belt CITZ Central Indian Tectonic Zone CG Closepet Granites DFB Delhi Fold Belt EGMB Eastern Ghats Mobile Belt GBF Great Boundary Fault HF Hafnium LA ICP MS Laser AbalationIon Coupled PlasmaMass Spectrometer NSL NaramadaSon Lineament Pb Lead SHRIMP Sensitive High Resolution Ion Microprobe TIMS Thermal Ionizati on Mass Spectrometer U Uranium

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10 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 Science A DETRITAL ZIRCON TRANSECT ACROSS THE SON VAL LEY SECTOR OF THE VINDHYAN BASIN, INDIA: CONSTRAINTS FOR BASIN EVOLUTION AND PALEOGEOGRAPHIC IMPLICATIONS FROM U Pb AND Hf ISOTOPIC DATA By Candler Coyle Turner December 2012 Chair: Joseph Meert Major: Geology The Vindhyan Supergroup, located in central peninsular India, is one of the largest and thickest Precambrian sedimentary successions of the world, outcropping over an area of over 104,000 km2. The Vindhyan is the largest of the socalled Purana basins in India. Split into the upper Vindhyan and the lower Vindhyan, the age of the Upper Vindhyan sedimentary sequence is the subject of considerable controversy. This study seeks to determine if the Vindhyan Basin is much older in age than a previously assigned Neoproterozoic age, the age of basin clo sure, source of sediments, and to discuss the nearby Trans Aravalli Vindhyans, or Marwar basin, and its relationship to the Vindhyan Basin. Multiple hypotheses have been forwarded concerning basin closure: some argue for an early Neoproterozoic to late M esoproterozoic closure (~1050 Ma) of Upper Vindhyan sedimentation whereas others argue for an Ediacaran Cambrian age. U Pb dating of detrital zircons from upper Vindhyan sedimentary rocks of the Son Valley sector, purported U Pb detrital zircon from the R ajasthan sector of the basin and paleomagnetic data from the Majhgawan kimberlite indicates a Mesoproterozoic age for the upper Vindhyans and supports the

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11 hypothesis that the Vindhyan and Marwar basin do not share a coevolutionary history. However, Hf iso topic data show that the Vindhyan and Marwar shared similar sources, most likely from the Aravalli region. U Pb data corroborates other provenances that provided detritus to the Vindhyan and Marwar basins. Paleographical implications can also be made from these detrital zircon age populations.

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12 CHAPTER 1 I NTRODUCTION The understanding of geologic events in the Precambrian is vital to understanding the evolution of the earth, plate tectonic theory and evolution of life. The Proterozoic Eon (2500 540 Ma) bra ckets an important time in Earths history that includes the amalg a m a tion and breakup of supercontinents (Dalziel 1997) such as the Paleoproterozoic age Columbia (Rogers 1996; Rogers and Santosh 2002; Meert 2002; Santosh et al. 2003; Zhao et al. 2004; Prad han et al. 2011; Kaur et al. 2012), the MesoNeoproterozoic age Rodinia (McMenamin and McMenamin 1990; Meert and Torsvik 2003; Meert and Powell 2001; Li et al. 2008; Pradhan et al. 2011) and the EdiacaranCambrian age Gondwana (Meert et al. 2003; Meert a nd Lieberman, 2008; Powell and Pisarevsky, 2002; Meert and Powell 2001; Pesonen et al. 2003; Pradhan et al. 2011). This time period also included vast global oceanic and atmospheric changes (Hoffman et al. 1998), the evolution leading up to the beginning of multicellu la r life (Knoll 1994) and major changes in upper crustal composition (Taylor and McLennan 1985). The Indian subcontinent is thought to have played a role in the supercontinent cycles listed above, with a Precambrian history spann ing nearly 3. 0 billion years of geologic time. The assembly of Peninsular India began in the early Archean with the development and formation of the Aravalli, Bundelkhand, Eastern Dharwar, Western Dharwar, Bastar, and Singhbhum Cratons in conjunction with the Southern Granulite Province ( Figure 11 ) T he progressive development of each of these nuclei included the formation of tonalitetrondhjemite gneissic complexes, greenstone belts and late phase granitic intrusions. While each craton developed independently, there are several key intervals of time that led to the formation of Peninsular India (Meert et al.,

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13 2010, represented by basement rocks dated to ~3.6 Ga, ~3.5 Ga, ~3.4 Ga ~3.3 Ga ~3.2 Ga ~2.7 Ga (Meert et al. 2010) These cratonic nuclei are believed to have stabilized by 2.52.6 Ga (Meert et al., 2010; Rogers, 1998), a time interval marked by widespread granitic magmatism T he exact timing of protoIndia assembly is contentious because the nature and age of tectonic events in the suture zone between the Northern and Southern Indian blocks, the Central Indian Tectonic Zone (CITZ), may indicate that protoIndia was not fully formed until the Mesoproterozoic (Meert et al. 2010 and sources therein; Bhowmik et al. 2011; 2012). Recent tectonometamorphic reconstructions (Bhandari et al. 2011) suggest that Early Mesoproterozoic orogenesis was an integral component of crustal growth and assembly in central, eastern, and northeastern India. A variety of ages are attributed to an array of terranes located i n the CITZ, representing orogenic events occurring at 2.5 Ga, ~1.6 Ga, ~1.5 Ga, and ~1.4 Ga to as young as 0.94 Ga. Further west, in the Aravalli craton, available zircon, monzanite, and Sm Nd model ages indicate four important tectonomagmatic and tecto nothermal events in the region at 2.5 Ga, 1.85 Ga, 1.71.6 Ga and 1.00.9 Ga (Kaur et al. 2011; Mondal et al. 2002 ; Roy et al. 2005; Sarkar et al. 1989; Saha et al. 2008; Bhowmik et al. 2009; Chaudhri et al. 2003; Kaur et al. 2007; Lescuyer et al. 1993; Si varaman and Raval 1995; BijuSekhar et al. 2003; Kaur et al. 2006) Following cratonic stabilization of the Archean nuclei, a number of large Proterozoic basins developed on the cratons. The development of the basins was polyphase, but many of the larger basins formed at about the same time. The earliest Paleo to early Mesoproterozoic phase of basin formation is represented in the Aravalli,

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14 Lower Vindhyan, Lower Chhattisgarh and Cuddapah Basins ( Figure 11 ). During the late Mesoproterozoic to early Neoproterozoic sedimentary sequences are found in the Upper Vindhyan, Upper Chhattisgarh and Indravati Basins The final phase of Precambrian basin formation occurred in the Late Neoproterozoic and includes sedimentary deposits in the Marwar Basin, the Kurnool Group of the Cuddapah Basin, and several basins now located in Himalayas (Krol Tal and Salt Range ; Figure 12 ) Historically, all of these basins were dubbed the Purana (Hindi for ancient ) and collectively cover hundreds of thousands of square kilom eters of the Indian subcontinent ( Figure 1 1 ; Chaudhuri et al. 2002) The Purana basins are believed to represent the infill of failed rifts that developed on earlier Archean and/or early Paleoproterzoic cratonic blocks (Ram et al. 1996; Chaudhuri et al. 2002). The basins are bounded by normal faults visible on seismic profiles, geologic mapping, and gravity data and those observations led to a general consensus that all are rift related (Prasad and Rao, 2006; Ram et al., 1996; Chaudhuri et al., 2002). Th e sedimentary sequences within t hese basins provide critical groundtruth when attempting to decipher the tectonic history of the Indian subcontinent and its role in global events. In addition to standard sedimentary analyses and interpretations, the us e of detrital zircons from clastic sedimentary rocks has become a popular tool used in sedimentary correlation and sedimentary provenance studies (Fedo et al. 2003). U Pb ages derived from single detrital zircon grains can be used to identify provenance c omponents in a sedimentary unit, to correlate between sedimentary sequences, to determine a maximum limit for the age of deposition, and to study crustal evolutionary processes. This type of geochronology is advantageous because the

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15 abundance of zircon does not change drastically during sediment transport due to the inherent stability of zircon (Hietpas et al. 2012). The applicability of these data is further enhanced when cathodoluminescence ( CL ) imaging is used to detect zircon zoning In the case of z oned zircons, additional information regarding the polyphase magmatic and/or metamorphic history of the individual zircon can be resolved (Hietpas et al. 2011 and sources therein). The Marwar Basin lies to the west of the Vindhyan basin across the Aravall i Mountain range, in northwestern Rajasthan and the Marwar Supergroup is often referred to as the Trans Aravalli Vindhyans ( Heron 1932; Kumar and Pandey 2008; Pandey and Bahadur et al. 2009) These two basins provide promising areas to conduct sedimentary provenance analyses due to the long depositional history collectively recorded in both basins (Vindhyan sediments are estimated to have been deposited between ~1.8 to ~ 1.0 Ga and the deposition of the Marwar is estimated to span from ~750 Ma to ~521 Ma ) along with limited deformation/metamorphism in each basin. Additionally both basins are located in proximity to the CITZ and Aravalli Delhi Fold belts that may have provided a significant component of detritus and therefore may aid in identifying the ag es of different magmatic and metamorphic events in those regions These zircons also have the potential to document information on source lithology in the surrounding region, constrain the timing of sediment deposition into each basin, and ultimately determine the tectonic setting at the time of deposition. The Marwar sequence is younger than the neighboring ~750 Ma Malani igneous rocks. If the Upper Vindhyans (near Rajasthan) are agecorrelative, it is possible that they would also show some input from t he Malani Igneous Province, but previous

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16 studies focused on Upper Vindhyan rocks adjacent to the Malani Igneous province (comprised of three magmatic phases, a volcanic phase made up of predominant felsic and minor mafic flows, a granitic pluton phase, and a third phase of felsic and mafic dyke swarms; Gregory et al. 2009 ) showed no contribution (Malone et al. 2008). The work described in this paper serves as an expansion of the work by Malone et al. (2008) and McKenzie et al. (2011). Vindhyan and Marwar rocks were targeted immediately adjacent to the Malani igneous province for detrital zircon analyses. Samples span the entire Upper Vindhyan and Marwar stratigraphy. Our results can be compiled with those of Malone et al. (2008) and McKenzie et al. (2011) to yield detrital zircon spectra that should shed light on the regional activity that would have supplied sediment to these basins. It will also serve as a tool for comparison with other detrital zircon records from basins located on other cratonic bloc ks that are hypothesized to be in proximity with Peninsular India during the Rodinian and Gondwanan supercontinent cycles. Geologic Setting Vindhyan Basin The Vindhyan basin of the Bun delkhand Craton, located in central peninsular India, occupies a large portion of eastern Rajasthan state and extends well into the adjacent states of Madhya Pradesh and Uttar Pradesh ( Figure 11 and 1. 2) T he Vindhyan Basin covers an area of over 104,000 km2, with additional area covered by the Deccan Traps (to the south) a nd Indo Gangetic alluvium ( to the north and east; Figure 1 & 2 ; after Venkatachala et al. 1996). The Vindhyan Supergroup is divided into four Groups: the Semri Group and the Kaimur, Rewa, and Bhander Groups. The latter three Groups comprise the Upper Vindhyan and the units within the Semri Group are the Lower Vindhyan (Ray 2006; Figures 1.1 and 1. 3 ). Outcrops of the Vindhyan Basin

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17 are located in three different sectors: the Rajasthan sector, the Bundelkhand sector, and the Son Valley Sector ( Figure 12 ). The southern margin of the basin is delimited by the ENE WSW trending NarmadaSon lineament just north of the Satpura Mobile Belt, also known as the CITZ This complex Proterozoic orogenic belt formed during the accretion of the Bastar Singhbum Craton to the northern Bundelkhand Craton. The Mahakoshal Group and the Bijawar Group, exposed low grade metamorphic volcanosedimentary rocks, are located near the southern edge of the Vindhyan outcrop and the eastern flank of the Bundelkhand massif, respectively ( Chakraborty 2006). The western margin is marked by the NE SW trending Great Boundary Fault (GBF) adjacent to the Aravalli Delhi mountain range to the northwest that separates the Aravalli and Bundelkhand cratons. The basin is believed to continue beneath the Gangetic alluvial plain beyond the northernmost outcrop existing today (Chakraborty 2006; Figure 1). Lower Vindhyan Sequence The Lower Vindhyan sedimentary sequence is often referred to as the Semri Series ( Figure 13 ) Age constraints on the Semr i Series are robust for the bulk of the sedimentary package. Sedimentation is believed to have started sometime prior to 1721 Ma and continued until about 1600 Ma without any major breaks in deposition (Ray et al. 2006). The Lower Vindhyan units unconfor mably lie atop the Bundelkhand Granite basement rocks of this region dated to 2492 10 Ma (Mondal et al. 2002) or the 1854 7 Ma Hindoli Group (Deb et al. 2003) Geochronologic constraints on lower Vindhyan sedimentation include a whole rock Pb Pb age o f 1729 Ma on the Kajrahat Limestone ( Sarangi et al. 2004). The Kajrahat is overlain by the Deonar Porcellanite, Rampur shale and Rhotas limestone. The Deonar Porcellanite yielded two robust U Pb

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18 zircon ages of 1630.7 0.4 Ma (TIMS, Ray et al., 2002) and 1628 8 Ma ( SHRIMP ; Rasmussen et al. 2002 Zircons from volcaniclastics within the Rampur shale were dated at 1599 8 Ma ( SHRIMP, Rassmussen et al. 2002). Pb Pb ages from the Rhotas limestone obtained by Ray et al. (2003) and Sarangi (2004) are compar able though with somewhat large errors ( 1601 130 Ma and 1599 48 Ma) Based on these ages, sedimentation in the Lower Vindhyan basin began <1850 Ma and ended around ~15501600 Ma. A basin wide angular and erosional unconformity separates the Rhotas li mestone from the overlying Kaimur Group Upper Vindhyan Sequence Ages constraints on Upper Vindhyan sedimentation are more problematic Current estimates put the onset of Upper Vindhyan sedimentation in the Mesoproterozoic (>1100 Ma) and the cessation of sedimentation as young as Cambrian (Malone et al., 2008, Azmi et al., 2010). The best age constraints for the Upper Vindhyan sediments are derived from the 40Ar -39Ar age of 1073.5 13.7 Ma for the Majhgawan kimberlite that intrudes the Baghain sandstone ( Kaimur Group; Figure 13 ; Gregory et al. 2006) Based on this age, sedimentation of the Kaimur sandstone began prior to the intrusion and therefore the onset of Upper Vindhyan sedimentation is reliably constrained to the Mesoproterozoic. Other attemp ts to establish the age of the upper Vindhyan sediments give contradictory results. De (2003, 2006) argued that Upper Vindhyan sedimentation continued into the Ediacaran based on fossils in the Bhander limestone. Azmi et al. (2010) reject all geochronological data and argue that sedimentation within the Upper and Lower Vindhyan sequence is of Ediacaran age.

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19 Gregory et al. (2006) noted that the virtual geomagnetic pole (VGP) from the Majhgawan kimberlite was identical to previously published paleomagnetic poles from the Bhander and Rewa Groups. They suggested that this may signify that deposition of the Bhander Rewa Groups was confined to the Mesoproterozoic. Additional support for this hypothesis was given by Malone et al. (2008) based on an analysis of detrital zircon in the Vindhyan basin along with a comprehensive paleomagnetic study of the Bhander Rewa Groups. Malone et al. (2008) noted a lack of detrital input into the basin younger than ~1000 Ma. While absence of younger detritus can be due to num erous causes, the paleomagnetic data from the Bhander Rewa Groups confirmed the suspicions of Gregory et al. (2006). Subsequent reinforcement of a Mesoproterozoic depositional age is derived from a paleomagnetic study of the Mahoba dyke in the Bundelkhand craton (just north of the Son Valley sector ; Pradhan et al., 201 2 ). This dyke is dated to 1090 Ma and also yields a paleomagnetic direction indistinguishable from the Majhgawan and Bhander Rewa supporting the hypothesis that a Mesoproterozoic age may be assigned to these sediments Marwar Basin To the west the Vindhyan Basin, beyond the Aravalli Delhi Range is the Neoproterozoic Cambrian age Marwar Basin ( Figure 14 ; Davis et al. 2011) The Marwar Supergroup (MS ; Khan 1971) is situated in the state of R ajasthan, India and extends from south of Nagaur in the east to north of Pokaran in the west, with an estimated thickness of 10002000 m ( Figure 1 3 & 1. 4; Pandey and Bahadur 2009). The Marwar Basin is considered by some to be the westerly extension of th e upper Vindhyans across the Aravalli axis ( Figure 11 ; Heron 1932; Pandey and Bahadur 2009). The assumption of contemporaneous deposition in both the Upper Vindhyan

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20 and Marwar basins was based up on lithological similarities, the lack of diagnostic fos sils and the lack of penetrative deformation in both basins (Heron 1932; Heron 1936; Verma 1991). The lithostratigraphy of the Marwar Supergroup is divided into 3 groups: the lower Jodhpur Group, the middle Bilara Group, and the upper Nagaur Group ( Figur e 14 ). The Pokaran boulder bed of the Jodhpur Group lies unconformably above the 750800 Ma Malani Igneous Suite, ( Figure 13 & 1. 4; Gregory et al., 2009; Van Lente et al., 2009; Pradhan et al., 2010; Torsvik et al., 2001), and contains cobbles of Malani and older igneous rocks (Meert et al. 2010; Chakrabartu et al. 2004; Ramakrishnan and Vaidyanadhan 2008). Recent age estimates would place the Lower Marwar in the time frame for Gaskiers (~ 580 Ma) or Marinoan (~ 635 Ma) glaciations, but there is no evid ence for a glacial origin of these rocks (i.e. dropstones, striated clasts; Meert et al. 2010). The exact age range of the Marwar Supergroup is not precisely known, but it is typically correlated with the EdiacaranCambrian sequences in the Salt Range of Pakistan the Krol Tal Belt of the Himalayas and the Huqf Supergroup (Oman) based on similar trace fossils lithologies and macrofossils ( Figure 14 ; Jones 1970; Kumar and Pandey 2008, 2010; Cozzi et al., 2012). Summary Recent geochronologic data support the hypothesis that the Marwar may not be a continuation of the Vindhyan Supergroup. Malone et al. (2008) examined the age spectra of detrital zircons in the Sonia and Girbakhar sandstones from the Marwar Supergroup that showed distinct differences from that of the nearby Upper Bhander Group in the Rajasthan sector (Figure 1 2) In particular, Malone et al. (2008) noted the presence of <1000 Ma zircons in the Marwar Supergroup. Based partly on this

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21 difference, Malone et al. (2008) argued for distinct b asinal histories for the Marwar and Vindhyan basins. This difference in zircon populations was reinforced by a recent study of McKenzie et al. (2011). In addition, new fossil finds ( Kumar and Pandey 2009; Kumar et al. 2009) of Ediacaran and younger biota provide firm evidence that sedimentation in the Marwar basin is confined to the interval from <750 Ma to the earliest Cambrian (~521 Ma). Davis et al. (2012) and Cozzi et al. (2012) further limit the age of sedimentation in the Marwar Supergroup to between 6355 21 Ma based on the lack of glacial deposits in the Marwar and intrabasinal comparisons with Oman.

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22 Figure 11 Map of continental India and the locations of Purana basins, distribution of cratons, and tectonic domains (modified from Rao and Reddy 2002). Important Abbreviations: Delhi Fold Belt (DFB); Aravalli Fold Belt (AFB); Naramada Son Lineament (NSL); Satpura Mobile Belt (SMB; also known as Central Indian Tectonic Zone, CITZ); Godavari Basin (GB); Mahandi Rift (MR); Closepet Granites (CG); Eastern Ghats Mobile Belt (EGMB); Central Indian Suture (CIS); Bhavani Palghat Mobile Belt (BPMB).

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23 Figure 12 Geologic Map of the Vindhyan Basin. A) Map of continental India; B) Rajasthan Sector; C) Son Valley Sector; D) Bundelkhand Sector. The NarmadaSon Lineament creates the eastern most boundary of the Vindhyan Basin, while the Great Boundary Fault (GBF) delimits the western boundary. To the west of the GBF lie the Aravalli/Delhi Fold Belts and their successive sedimentary sequences. Further to the w est, the Marwar Supergroup (represented by the Jodphur Sandstone in this figure) overlies the Malani Rhyolites Detrital zircon whole rock samples were selected from the Rajasthan and Son Valley sectors.

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24 Figure 3: Figure 13 Correlations and Stratigraphy of the Vindhyan Supergroup from both the Son Valley and Rajasthan Sectors. Age constraints provided from Gregory et al. (2006), Sarangi et al. (2004), Ray et al. (2003, 2002), De (2006), and Malone et al. (2008). Note tha t an unconformity separates the Lower and Upper Vindhyans.

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25 Figure 14 Marwar Stratigraphy and correlations to the Salt Range of Pakistan, the Krol Tal belt of the Himalayas, and the Huqf Supergroup of Oman. Note that the Krol Tal and Huqf Supergroup con tain stratigraphy from the Marinoan time period.

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26 CHAPTER 2 GEOCHRONOLOGY METHODS Samples were taken in the Son Valley and Rajasthan sectors of the Vindhyan basin along with additional samples from the Marwar Supergroup in 2009 and 2011. The s amples were broken down with a sledge hammer and jaw crusher and further disk milled to reduce sediment into sand grain size. Samples were further separated by size Density separation by water table and heavy liquid was followed by magnetic separation techniques to isolate individual grains of zircon. These grains were examined with an optical microscope and handpicked from the appropriate fractions (nonmagnetics at 5, .5 A). Zircons were then mounted into an epoxy plug and polished to expose surfaces of the zircons Cathodoluminescence (CL) imaging was then taken by SEM (Scanning Electron Microscope) as well as reflected light microscope imaging The epoxy plugs were sonicated and cleaned in nitric acid to remove any common Pb surface contamination. Zircon U Pb analyses were carried out at the Department of Geological Sciences, University of Florida, using the NuPla sma (Nu Instruments, UK) multicollector inductively coupled plasma mass spectrometer (LA MC ICP MS). The mounted zircon grains were ablated using an attached New Wave 213 nm ultraviolet laser Pb analyses Ar and He carrier gas was used for sample transport into the mass spectrometer. Before each ablation, a zero measurement was taken for 20 s in order to m ake online corrections for isobaric interfere nces, especially from 204Hg, a common component of argon gas. Following this zero period, laser ablation commenced for 30 s, keeping a constant ablation pit depth,

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27 ther efore reducing elemental fractionation. Ablation spot locations were recorded to in sure the direct correlation of U Pb ages to the data pr oduced from Hf ablation and to keep record of where the spot was taken (in this case, if the zircon was zoned, spots would be taken on both the rim and core of the zircon and recorded accordingly). A blations occurred in intervals of 10 zircons, directly preceded and followed by ablation of 2 FC 1 standard zircons. The U Pb and Hf isotopic data were recorded using Nu instruments Time Resolved Analysis (TRA) software. This software allows the user to calculate isotopic ratios from a desired time segment of data, aiding in the avoidance of complications due to grain defects or surface contamination. The raw isotopic data garnered from the LA MC ICP MS were imported into a Microsoft Excel spreadsheet ( Calamari) where corrections for instrumental drift and mass bias were undertaken by normalization to standard zircon FC 1 from the Duluth Gabbro, dated at 1099.0 0.7 Ma and 1099.1 0.5 Ma by Mattinson (2010) Figures were generated and errors calculated using Isopolt/Ex plotting software Version 4.11 by Ludwig (2008). Following U Pb analyses, Hf isotopic analyses were undertaken on the same LA MC ICP MS. The same zircons used in U Pb analyses were ablated, making sure to note the identity of each zircon so that U Pb data and Hf data could be compared. A with a 120 s period of ablation and monitored with FC 1 zircon (Woodhead et al. 2004) Hf isotopic measurements were made following the procedures outlin ed by Mueller et al. (2008). Measured and mass bias corrected 176Lu/177Hf ratios were used to calculate initial 176Hf /177Hf ratios, as described by Griffin et al. (2000, 2002). Overall,

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28 the difference between the present day measured and calculated initi al 176Hf /177Hf ratios in most cases is <1 epsilon ( ) unit, due to very low Lu/Hf ratios Depleted mantle values are based on a linear model = 0 at 4.56 Ga and 16 at 0 Ga) from Mueller et al. (2008). Chondritic Uniform Reservoir ( CHUR) values are after Blichert Toft and Albarede (1997), as recommended by Patchett et al. (2004). The 176Lu decay constant ( 1:867 1011 yr1) is after Soderl und et al. (2004). Isotopic BSE values (Bulk silicate earth) are from Bouvier et al. (2008).

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29 CHAPTER 3 RESULTS U Pb Geochronology Grains that exhibited a discordance of > 10 % were excluded from our analysis If analyses produced U Pb ages of <1000 Ma, 206Pb/238U ages were used in our results, while ages >1000 Ma are represented by 207Pb/206Pb ages. Discordances for each of these different isotopic age determinations can be found in Table 31 and Table 32. The results of all Marwar and Vindhyan detrital zi rcon samples are listed in Table 31 and Table 32 and are shown in Figures 3 1 and 3 2 Vindhyan Samples Kaimur sandstone sample I9 GS14 was recovered from a roadcrop just outside the town of Panna (Lat: 24 39 14.52 N, Long: 80 16 10.38 E) I9 GS14 is a well sorted, fine grained, quartz rich sandstone. This sample provided 39 concordant detrital zircons. These zircons ranged in age from ~1 .0 2.0 Ga with a modal abundance at ~1.6 Ga T he Rewa sandstone sample I9GS16 was collected just above the Kaimur Rewa contact near Bhadaphur (Lat: 24 10 49.08 N, Long: 80 48 42.3 E) I9 GS16 is a wellsorted, fine grained, brown sandstone. A total of 33 concordant zircons exhibited ages between ~1.0~1.9 Ga along with a single Archean zircon dated at 2555 16 Ma A second crossbedded Rewa sandstone was collected up section from the Kaimur Rewa contact (Lat: 24 12 10.38 N, Long: 80 48 45.66 E) This s ample (I9GS17) produced 29 concordant ages between ~1 .0 ~1.8 Ga, along with two Archean zirc ons, dated at ~2.48 Ga and ~2.85 Ga.

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30 Three samples from the Bhander sandstones were collected. Sample I9 GS20, a very fine grained, well sorted, white sandstone, was collected from a predominately shale unit near Madhogarh (Lat: 24 34 20.28 N, Long: 80 52 15.90 E) A total of 48 concordant detrital zircons were analyzed, with ages of 1.15 1.8 Ga along with a single Archean zircon with an age of 3 .1 Ga Bhander sandstone sample I9 GS23 was collected from folded units within the Great Boundary Fault zone near Bundi (Lat: 25 26 50.1 N, Long: 75 36 52.26 E) T he sandstone is pink relatively fine grained with symmetric ripple marks. A total of 50 zircons yielded c oncordant ages w ith ages ranging between ~1.0 ~1.9 Ga. The sample contains an earl y Paleoproterozoic zircon dated to 2.3 G a and an Archean zircon dated to 2.6 G a. Bhander sample I9 GS24 is located near Bundi, but away from the Great Boundary fault and lower in the section than sample I9GS23 (Lat: 25 25 51.90 N, Long: 75 34 56.76 ) The sandstone is white, poorly sorted, medium to coarse grained, and contains pebble sized lithic fragments. T his sandstone yielded 64 concordant detrita l zircon ages ranging from ~1 ~2 Ga. Ages are concentrated in two intervals at 1.6 Ga and 1.8 Ga. Marwar Samples Five samples were analyzed from different units of the Marwar Supergroup. These include(a) Basal Marwar sandstone (contact with Malani Igneous Rocks; I9GS4) (b) Marwar sandstone from a quarry in Balesar (I9GS5), (c) a Nagaur sandstone (I9GS6 ) (d) a Jodhpur Marwar sandstone (G 113), and (e) Lower Marwar sandstone from the Pokaran area ( I 11 GS19 ; Figure 14 ).

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31 The basal Marwar sandstone that is near the contact with the Malani Igneous rocks (sample I9 GS4 ) yielded 52 concordant detrital zir cons. I9 GS4 (Lat: 26 45 1 1 .6 4 N, Long: 71 33 1 2 .66 E) is deep purple/brown in color with white to tan laminations, with well sorted, intermediate sized grains. Ages range from ~ 0.7 1.0 Ga, ~1.6 1. 8 Ga and smaller populations of early Paleoproterozoic to Archean ages ranging from ~2.3 2.7 Ga. A Sonia Sand stone, I9 GS5 (Jodphur Group) yielded 26 concordant detrital zircons (Lat: 26 24 38.28 N, Long: 72 29 11.94 E) I9 GS5 is characterized as a finely laminated, orange to tan in color, well s orted, intermediate sized grain quartz sandstone. The sample contains zircons with ages ranging from ~700900 Ma, ~1.2, and ~1.61.9 Ga. R elatively large concentrations of abundances are at ~1.7 and ~1.8 Ga. A Nagaur Formation sandstone, I9 GS6 yielded 25 concordant detrital zircon ages (Lat: 27 02 42.72 N, Long: 73 29 59.58 E) I9 GS6 is a white to grey, poorly sorted, coarse to medium grained sandstone with large clasts of pebble sized quartz and other lithic clasts. Prevalent zircon ages are ~700900 Ma, ~1.7 1.8 Ga. I9 GS6 contains two Archean zircons dated to 3198 5 Ma and 3260 29 Ma. A Girbahakar sandstone, I11 G S1 3 yielded 13 concordant detrital zircons (Lat: 26 19 50.45, Long: 73 0 19.40) I11 GS13 is a pebble conglomerate sandst one Zircons range in age between ~800 Ma 1.7 Ga, A Nagaur sandstone collected from near the Inana Village (I11 GS19) yielded 42 concordant detrital zircons (Lat: 27 6 36.25, Long 73 50 17.74) I11 GS19 is a reddish sandstone containing abundant ri pple marks and cross bedding. Smaller

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32 amounts of young er zircons are present in this sample when compared to other yields from the Marwar, ranging from ~7001000 Ma. Other ages range from ~1.71.9 Ga. There are several older zircon grains of early Paleopr oterozoic and Archean age that are 2480 12 Ma, 2512 17 Ma, 3114 52 Ma, 3196 13 Ma, and 3249 17 Ma. Hf Isotop es Samples for Hf isotopic study were chosen from the Marwar and Vindhyan Supergroups that had similar zircon ages between ~1.71.8 Ga. Fifty two detrital zircons were analyzed from the Marwar sequence and 39 detrital zircons were analyzed from Upper Vindhyan samples (Table 33) Present day 176Hf/177Hf values for this suite of zircons ranged from 0.281830.28133 For Marwar samples, 176Hf/177Hf values lie between 0.28133 and 0.28173 Vindhyan samples showed 176Hf/177Hf val ues between 0.28139 and 0.28183 Deviations of Hf isotopic composition from chrondritic at any time, t, are expressed in epsilon units (parts per ten thousand), which is given by the formula: 176Hf/177Hf)t / (176Hf/177Hf)chondrites 1 ] 104 (Kinny and Maas). Marwar and upper Vindhyan sandstone samples reveal zircons with epsilon ( ) Hf( t ) values that are mostly comprised of subchondritic Hf( t ) values, ranging from 13.8 to 0.2. 1 2 zircons (4 Marwar, 8 Vindhyan) exhibited superchondritic Hf( t ) values ( i.e. values between the Chondritic Uniform Reservoir (CHUR) and depleted mantle (DM) reference lines ), ranging from 0.2 to 9.9 (Table 33, Figure 33 ) Negative Hf( t ) values suggest that these zircons were derived from ancient crust or reworking of the ancient crust in whole or in part P ositive Hf( t ) values are thought to reflect a strong influence from a juvenile source (s). TDM v alues (represent ing the minimum age for the sour ce region that produced the zircon bearing magma) range from 1.94 2.67 Ga (Table 33 ) It should

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33 be noted that values with a % corrected value of greater than 25% are not reliable, but were included because they do not form the limits of any group of val ues in our data.

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34 Table 3 1. Upper Vindhyan U Pb Isotopic Data Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb /235 U Disc I9GS 14_5r 2.086 2.5 0.1905 2.5 0.07942 0.468 1125 26 1144 17 1183 9.2 5 2 I9GS 14_5r.2 2.105 2.8 0.1905 2.7 0.08014 0.441 1125 28 1150 19 1200 8.7 6 2 I9GS 14_15c 5.874 2.7 0.3386 2.7 0.12583 0.299 1881 44 1957 24 2040 5.3 8 4 I9GS 14_15r 6.404 2.5 0.3714 2.5 0.12506 0.339 2038 44 2032 22 2030 6.0 0 0 I9GS14 3c 4.715 7.5 0. 3135 7.4 0.10908 0.991 1759 114 1770 62 1784 18.0 1 1 I9GS14 4c 1.799 7.3 0.1716 7.2 0.07603 1.343 1022 68 1045 47 1096 26.9 7 2 I9GS14 10c 3.770 7.4 0.2783 7.3 0.09826 0.931 1584 102 1586 58 1591 17.4 0 0 I9GS14 16c 2.103 7.2 0.1939 7.1 0.07869 1.006 1 143 74 1150 49 1164 19.9 2 1 I9GS14 18c 1.673 7.4 0.1639 7.3 0.07402 1.161 979 67 998 47 1042 23.4 6 2 I9GS14 22c 4.147 5.3 0.3061 4.6 0.09826 2.562 1723 70 1663 43 1591 47.8 8 4 I9GS14 23c 2.403 6.0 0.2101 5.5 0.08296 2.602 1230 61 1243 43 1268 50.7 3 1 I9GS14 24c 3.792 5.4 0.2778 4.8 0.09902 2.551 1581 67 1591 43 1606 47.5 2 1 I9GS14 25c 1.975 4.7 0.1879 3.9 0.07623 2.626 1111 40 1107 32 1101 52.5 1 0 I9GS14 26c 4.656 5.4 0.3087 4.8 0.10940 2.556 1736 73 1759 45 1789 46.5 3 1 I9GS14 27c 4.057 4. 7 0.2879 3.9 0.10222 2.575 1632 57 1645 38 1665 47.6 2 1 I9GS14 28c 3.627 5.1 0.2697 4.4 0.09752 2.562 1541 60 1555 40 1577 47.9 2 1 I9GS14 31c 2.168 4.8 0.1964 4.0 0.08003 2.672 1157 42 1171 33 1198 52.6 3 1

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35 Table 3 1. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS14 33c 3.870 5.2 0.2698 4.1 0.10403 3.216 1541 56 1607 41 1697 59.2 9 4 I9GS14 34c 2.196 4.5 0.1996 3.7 0.07979 2.571 1174 40 1180 31 1192 50.7 1 0 I9GS14 37c 2.108 5.0 0.1923 4.1 0.07950 2.796 1135 42 1151 34 1185 55.2 4 1 I9GS14 43c 4.828 4.7 0.3166 4.0 0.11059 2.568 1775 62 1790 40 1809 46.6 2 1 I9GS14 44c 2.163 4.7 0 .1985 3.9 0.07903 2.556 1168 42 1169 32 1173 50.5 0 0 I9GS14 51c 3.623 5.2 0.2686 4.5 0.09785 2.552 1535 62 1554 41 1583 47.7 3 1 I9GS14 52c 4.601 4.6 0.3076 3.9 0.10849 2.555 1730 58 1749 38 1774 46.6 2 1 I9GS14 53c 4.158 5.1 0.2932 4.4 0.10284 2.578 1 659 64 1665 41 1676 47.6 1 0 I9GS14 54c 2.052 5.3 0.1920 4.6 0.07752 2.592 1133 48 1133 36 1135 51.5 0 0 I9GS14 56c 4.516 4.6 0.3085 3.9 0.10619 2.548 1735 59 1734 38 1735 46.7 0 0 I9GS14 59r 2.932 5.8 0.2290 5.1 0.09287 2.797 1330 61 1390 43 1485 52.9 10 4 I9GS14 64r 3.582 5.0 0.2658 4.3 0.09772 2.582 1521 59 1545 40 1581 48.2 4 2 I9GS14 66c 1.792 5.1 0.1732 4.3 0.07504 2.730 1030 41 1042 33 1070 54.8 4 1 I9GS14 68r 1.699 4.8 0.1684 4.0 0.07314 2.576 1004 37 1008 30 1018 52.1 1 0 I9GS14 71c 2.112 5. 3 0.1910 4.5 0.08020 2.769 1128 47 1153 36 1202 54.5 6 2 I9GS14 73c 1.736 4.8 0.1666 4.0 0.07555 2.761 994 37 1022 31 1083 55.3 8 3 I9GS14 75c 2.130 4.7 0.1960 3.9 0.07881 2.556 1155 41 1158 32 1167 50.6 1 0

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36 Table 3 1 Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS14 76c 1.693 4.7 0.1657 3.9 0.07414 2.631 989 36 1006 30 1045 53.0 5 2 I9GS14 77c 4.562 4.8 0.3026 4.0 0.10935 2.551 1705 60 1742 39 1789 46.4 5 2 I9GS14 78c 4.630 4.8 0.3096 4.1 0.10846 2.547 1740 63 1754 40 1774 46.4 2 1 I9GS14 79c 2.077 4.7 0.1873 3.9 0.08044 2.631 1107 39 1141 32 1208 51.7 8 3 I9GS14 82c 3.723 6.1 0. 2785 6.1 0.09695 0.309 1585 86 1576 49 1566 5.8 1 1 I9GS14 83c 2.359 5.8 0.2089 5.8 0.08191 0.883 1224 64 1230 41 1243 17.3 2 1 I9GS14 85c 2.067 6.4 0.1896 6.3 0.07906 0.778 1120 65 1138 43 1174 15.4 5 2 I9GS14 86c 2.125 5.9 0.1970 5.9 0.07824 0.785 1 160 62 1157 40 1153 15.6 1 0 I9GS16_ 3r 2.059 5.0 0.1855 4.9 0.08049 1.238 1098 49 1135 34 1209 24.3 9 3 I9GS16_ 3r.2 2.060 5.0 0.1897 4.7 0.07876 1.644 1121 48 1135 34 1166 32.5 4 1 I9GS16_ 6c 3.829 5.1 0.2852 5.0 0.09738 1.039 1619 71 1599 41 1574 19.4 3 1 I9GS16_ 7c 4.175 4.9 0.2950 4.8 0.10264 1.063 1668 70 1669 40 1672 19.6 0 0 I9GS16_ 8r 1.943 4.7 0.1810 4.6 0.07783 1.254 1073 45 1096 31 1143 24.9 6 2 I9GS16_ 8c 1.909 4.5 0.1802 4.3 0.07682 1.146 1069 43 1084 30 1117 22.8 4 1 I9GS16_ 11r 3.984 4.9 0.2837 4.8 0.10187 1.065 1611 68 1631 39 1658 19.7 3 1 I9GS16_ 11r.2 3.900 4.6 0.2787 4.5 0.10152 1.049 1586 63 1614 37 1652 19.4 4 2 I9GS16_ 14r 3.697 4.4 0.2630 4.3 0.10196 1.092 1506 58 1570 35 1660 20.2 9 4

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37 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS16_ 17c 1.849 4.8 0.1760 4.6 0.07617 1.482 1046 44 1063 31 1100 29.6 5 2 I9GS16_ 20r 4.889 6.0 0.3099 4.9 0.11441 3.495 1742 74 1800 50 1871 63.0 7 3 I9GS16_ 22c 5.365 5.1 0.3425 5.0 0.11361 1.000 1900 82 1879 43 1858 18.0 2 1 I9GS16_ 23c 4.024 4.9 0.2872 4.8 0.10160 1.083 1629 69 1639 39 1654 20.0 1 1 I9GS16_ 27c 1.697 5.1 0.1650 4.9 0.07457 1.314 986 45 1007 32 1057 26.4 7 2 I9GS16_ 28c 3.709 4.9 0.2777 4.8 0.09690 1.005 1581 67 1573 39 1565 18.8 1 0 I9GS16_ 29c 3.732 5.1 0.2767 4.9 0.09784 1.023 1576 69 1578 40 1583 19.1 0 0 I9GS16_ 30c 1.711 5.3 0.1650 4.8 0.07519 2.237 985 43 1012 33 1074 44.9 8 3 I9GS16_ 32c 2.053 4.8 0.1863 4.5 0.07993 1.650 1102 46 1133 33 1195 32.5 8 3 I9GS16_ 33c 1.716 4.9 0.1677 4.8 0.07419 1.128 1000 44 1014 31 1047 22.7 4 1 I9GS16_ 34c 2.053 4.9 0.1867 4.8 0.07977 1.039 1104 48 1133 33 1191 20.5 7 3 I9GS16_ 36c 4.671 4.8 0.3118 4.7 0.10864 1.032 1751 72 1762 40 1777 18.8 1 1 I9GS16_ 37c 3.483 4.8 0.2649 4.7 0.09535 1.026 1516 63 1523 37 1535 19.3 1 0 I9GS16_ 39c 5.273 6.4 0.3206 6.1 0.11928 1.895 1794 96 1864 54 1945 33.8 8 4 I9GS16_ 43c 4.835 5. 0 0.3200 4.9 0.10959 1.122 1791 76 1791 42 1793 20.4 0 0 I9GS16_ 44c 2.852 5.1 0.2370 4.9 0.08727 1.028 1372 61 1369 38 1366 19.8 0 0

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38 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS16_ 48c 2.091 4.8 0.1898 4.7 0.07989 1.225 1121 48 1146 33 1194 24.1 6 2 I9GS16_ 49c 3.059 5.0 0.2393 4.9 0.09269 1.105 1384 61 1422 38 1482 20.9 7 3 I9GS16_ 51c 11.422 5.3 0.4881 5.2 0.16971 0.990 2565 110 2558 49 2555 16.6 0 0 I9GS16_ 53c 2.121 5.2 0.1903 4.9 0.08083 1.948 1124 50 1155 36 1217 38.3 8 3 I9GS16_ 56c 3.751 5.0 0.2779 4.9 0.09791 1.023 1582 69 1582 40 1585 19 .1 0 0 I9GS16_ 59c 1.683 4.8 0.1655 4.7 0.07378 1.129 988 43 1002 30 1035 22.8 5 1 I9GS16_ 60c 2.296 4.9 0.2064 4.8 0.08070 1.174 1210 53 1211 35 1214 23.1 0 0 I9GS17_ 9c 2.825 10.4 0.2249 10. 1 0.09112 2.450 1309 119 1362 77 1449 46.6 10 4 I9GS17_ 10c 2.14 9 10.4 0.1944 10. 2 0.08018 2.112 1146 107 1165 71 1201 41.6 5 2 I9GS17_ 11c 3.479 10.9 0.2550 10. 7 0.09893 2.082 1465 139 1522 84 1604 38.8 9 4 I9GS17_ 11r 3.395 10.4 0.2522 10. 2 0.09766 2.102 1451 131 1503 80 1580 39.3 8 3 I9GS17_ 13c 14.625 10.4 0.5233 1 0. 2 0.20268 2.109 2715 224 2791 97 2848 34.3 5 3 I9GS17_ 13r 14.399 10.4 0.5158 10. 2 0.20247 2.127 2683 222 2776 97 2846 34.6 6 3 I9GS17_ 16c 3.567 10.6 0.2598 10. 4 0.09957 2.084 1490 137 1542 82 1616 38.8 8 3 I9GS17_ 23c 1.561 10.4 0.1545 10. 2 0.07329 2.2 57 927 88 955 64 1022 45.6 9 3 I9GS17_ 3r 1.550 10.4 0.1543 10. 2 0.07289 2.098 926 87 951 63 1011 42.5 8 3 I9GS17_ 3c 1.543 10.5 0.1538 10. 2 0.07278 2.167 923 88 948 64 1008 43.9 8 3

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39 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS17_ 5c 99.432 13.7 0.9461 13. 5 0.76220 2.143 4296 417 4680 133 4600 36.9 7 8 I9GS17_ 58c 4.914 10.5 0.3171 10. 3 0.11239 2.103 1777 159 1804 87 1838 38.0 3 2 I9GS17_ 59c 1.666 10.6 0.1635 10. 3 0.07392 2.126 977 93 996 66 1039 42.9 6 2 I9GS17_ 26c 4.371 11.4 0.2974 11. 1 0.10662 2.264 1680 164 1707 92 1742 41.4 4 2 I9GS17_ 27c 4. 305 11.3 0.2887 10. 3 0.10817 4.457 1636 149 1694 91 1769 81.3 7 3 I9GS17_ 28c 10.219 10.5 0.4547 10. 2 0.16300 2.134 2418 205 2454 95 2487 35.9 3 1 I9GS17_ 29c.2 10.125 10.5 0.4512 10. 3 0.16275 2.090 2403 205 2446 95 2484 35.2 3 2 I9GS17_ 30c 3.731 10.5 0.2 766 10. 3 0.09784 2.221 1575 143 1578 83 1583 41.5 0 0 I9GS17_ 31c 2.592 10.5 0.2251 10. 3 0.08352 2.088 1310 122 1298 76 1281 40.6 2 1 I9GS17_ 32r 2.530 10.5 0.2199 10. 3 0.08344 2.084 1282 120 1280 75 1280 40.6 0 0 I9GS17_ 33r 1.585 10.4 0.1584 10. 2 0.072 57 2.089 949 90 964 64 1002 42.4 5 2 I9GS17_ 37c 4.065 10.6 0.2875 10. 4 0.10253 2.106 1631 149 1647 85 1670 38.9 2 1 I9GS17_ 38r 4.007 10.5 0.2857 10. 3 0.10170 2.096 1621 146 1635 83 1655 38.8 2 1 I9GS17_ 39c 3.397 10.6 0.2606 10. 4 0.09454 2.089 1494 138 1 503 81 1519 39.4 2 1 I9GS17_ 40c 2.103 10.6 0.1947 10. 4 0.07835 2.103 1148 109 1150 72 1156 41.7 1 0 I9GS17_ 43c 2.178 10.6 0.2006 10. 4 0.07874 2.132 1179 111 1174 72 1166 42.2 1 0 I9GS17_ 45r 3.086 10.5 0.2473 10. 3 0.09052 2.127 1426 131 1429 79 1437 40. 5 1 0

PAGE 40

40 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS17_ 53c 3.031 10.8 0.2369 10. 6 0.09280 2.141 1372 130 1415 81 1484 40.5 8 3 I9GS17_ 54c 3.623 10.5 0.2669 10. 3 0.09843 2.114 1526 140 1554 82 1595 39.4 4 2 I9GS20_ 2c 2.277 5.7 0.2054 5.5 0.08038 1.281 1206 60 1205 40 1206 25.2 0 0 I9GS20_ 5c 2.573 5.7 0.2203 5.6 0.08473 1.324 1284 65 1293 42 1309 25.7 2 1 I9GS20_ 10c 2.114 5 .7 0.1946 5.6 0.07879 1.283 1147 59 1153 39 1167 25.4 2 1 I9GS20_ 11c 4.966 5.7 0.3158 5.5 0.11404 1.254 1771 85 1813 47 1865 22.6 5 2 I9GS20_ 15c 2.350 6.3 0.2125 6.2 0.08020 1.274 1243 70 1227 45 1202 25.1 3 1 I9GS20_ 22c 2.302 5.9 0.1990 5.6 0.08386 1 .569 1171 60 1213 41 1289 30.5 9 3 I9GS20_ 23c 4.499 5.8 0.3061 5.6 0.10661 1.250 1723 85 1731 47 1742 22.9 1 0 I9GS20_ 24c 20.559 5.8 0.6195 5.6 0.24071 1.232 3110 138 3118 55 3125 19.6 0 0 I9GS20_ 25c 3.438 5.6 0.2603 5.5 0.09580 1.271 1492 73 1513 44 15 44 23.9 3 1 I9GS20_ 27c 4.807 5.6 0.3171 5.4 0.10997 1.324 1777 84 1786 47 1799 24.1 1 1 I9GS20_ 30c 3.710 5.5 0.2741 5.4 0.09816 1.250 1563 74 1573 44 1589 23.3 2 1 I9GS20_ 31c 5.360 5.8 0.3427 5.7 0.11345 1.244 1901 94 1878 49 1855 22.5 2 1 I9GS20_ 32c 5.211 5.7 0.3311 5.5 0.11414 1.241 1845 88 1854 48 1866 22.4 1 0 I9GS20_ 35c 2.058 5.6 0.1915 5.5 0.07797 1.263 1130 57 1135 38 1146 25.1 1 0 I9GS20_ 39c 4.535 5.8 0.3067 5.6 0.10727 1.238 1726 85 1737 48 1753 22.6 2 1

PAGE 41

41 Table 31. Continued Ratios A ges Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS20_ 40c 2.673 5.6 0.2276 5.4 0.08516 1.263 1323 65 1321 41 1319 24.4 0 0 I9GS20_ 42c 3.535 5.9 0.2671 5.7 0.09598 1.289 1527 77 1535 46 1547 24.2 1 0 I9GS20_ 44c 2.123 5.8 0.1958 5.6 0.07862 1.318 1154 59 1156 39 1163 26.1 1 0 I9GS20_ 46c 3.756 5.6 0.2764 5.5 0.09858 1.274 1574 77 1583 45 1597 23.7 1 1 I9GS20_ 48c 4.672 5.6 0 .3128 5.4 0.10831 1.261 1756 83 1762 46 1771 23.0 1 0 I9GS20_ 49c 3.724 5.6 0.2766 5.4 0.09763 1.281 1576 76 1576 44 1579 23.9 0 0 I9GS20_ 50c 2.050 5.7 0.1896 5.5 0.07841 1.438 1120 57 1132 39 1157 28.5 3 1 I9GS20_ 54c 4.640 5.9 0.3145 5.8 0.10701 1.250 1 764 89 1756 49 1749 22.8 1 0 I9GS20_ 55c 2.337 5.6 0.2081 5.4 0.08143 1.272 1220 60 1223 39 1232 24.9 1 0 I9GS20_ 56c 3.637 5.6 0.2674 5.5 0.09866 1.268 1529 74 1557 44 1599 23.6 4 2 I9GS20_ 59c 4.045 5.7 0.2951 5.5 0.09940 1.249 1669 81 1643 46 1613 23.2 3 2 I9GS20_ 60c 2.818 5.7 0.2351 5.5 0.08692 1.244 1362 68 1360 42 1359 23.9 0 0 I9GS20_ 61c 2.640 2.5 0.2210 2.2 0.08665 1.168 1288 26 1312 18 1353 22.5 5 2 I9GS20_ 62c 4.507 3.2 0.3094 3.1 0.10566 0.581 1739 47 1732 26 1726 10.7 1 0 I9GS20_ 64c 4.771 2.9 0.3079 2.7 0.11240 0.975 1732 41 1780 24 1839 17.6 6 3 I9GS20_ 65c 2.171 2.6 0.1968 2.4 0.08002 1.035 1159 25 1172 18 1198 20.4 3 1 I9GS20_ 66c 3.688 2.4 0.2758 2.4 0.09697 0.572 1572 33 1568 19 1567 10.7 0 0

PAGE 42

42 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS20_ 67c 2.128 2.5 0.1967 2.5 0.07849 0.548 1158 26 1158 17 1159 10.8 0 0 I9GS20_ 68c 3.981 2.3 0.2910 2.2 0.09921 0.599 1648 32 1630 19 1609 11.1 2 1 I9GS20_ 70c 3.671 2.3 0.2718 2.2 0.09797 0.689 1551 31 1565 19 1586 12.9 2 1 I9GS20_ 72c 3.895 2.5 0.2835 2.4 0.09964 0.578 1610 34 1612 20 1617 10.8 0 0 I9GS20_ 73c 5.128 2.6 0.3275 2.5 0.11356 0.673 1828 40 1840 22 1857 12.1 2 1 I9GS20_ 76c 2.920 2.6 0.2399 2.5 0.08829 0.605 1387 31 1387 20 1389 11.6 0 0 I9GS20_ 77c 2.711 1.9 0.2223 1.8 0.08842 0.582 1295 21 1331 14 1392 11.2 7 3 I9GS20_ 78c 2.134 2.7 0.1986 2.6 0.07790 0.694 1169 27 1160 18 1144 13.8 2 1 I9GS20_ 79c 5.391 2.5 0.3432 2.4 0.11392 0.558 1904 40 1883 21 1863 10.1 2 1 I9GS20_ 81c 4.769 2.8 0.3164 2.7 0.10929 0.551 1774 42 1779 23 1788 10.0 1 0 I9GS20_ 82c 2.643 2.8 0.2262 2.7 0.08473 0.572 1316 32 1312 20 1309 11.1 1 0 I9GS20_ 83c 3.564 2.5 0.2579 2.4 0.10025 0.834 1480 32 1541 20 1629 15.5 9 4 I9GS20_ 86c 3.096 2.3 0.2470 2.2 0.09091 0.557 1424 28 1432 17 1445 10.6 1 1 I9GS20_ 87c 3.513 2.6 0.2649 2.5 0.09619 0.666 1516 34 1530 20 1551 12.5 2 1 I9GS20_ 89c 5. 018 2.4 0.3239 2.3 0.11235 0.700 1810 37 1822 20 1838 12.7 1 1 I9GS20_ 90c 5.426 2.3 0.3393 2.2 0.11600 0.645 1885 36 1889 20 1895 11.6 1 0 I9GS23 2c 3.354 9.0 0.2599 9.0 0.09358 1.017 1491 119 1493 69 1500 19.2 1 0

PAGE 43

43 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS23 3c 1.811 9.1 0.1771 9.1 0.07419 1.162 1052 88 1049 59 1047 23.4 0 0 I9GS23 5c 4.814 8.9 0.3220 8.9 0.10843 0.960 1801 139 1787 74 1773 17.5 2 1 I9GS23 6c 2.349 9.1 0.2132 9.0 0.07992 0.991 1247 102 1227 63 1195 19.5 4 2 I9GS23 8c 5.201 9.0 0.3286 8.9 0.11479 1.293 1833 141 1852 75 1877 23.3 2 1 I9GS23 10c 2.774 9. 3 0.2285 9.2 0.08805 1.658 1327 110 1348 68 1384 31.8 4 2 I9GS23 12c 3.497 8.9 0.2627 8.8 0.09652 1.004 1505 118 1526 69 1558 18.8 3 1 I9GS23 13c 4.219 9.6 0.2989 9.5 0.10238 1.386 1687 140 1678 77 1668 25.6 1 1 I9GS23 15c 3.019 9.1 0.2426 9.1 0.09025 1.093 1401 114 1412 68 1431 20.8 2 1 I9GS23 17c 5.024 9.6 0.3170 9.5 0.11496 1.419 1776 146 1823 80 1879 25.5 5 3 I9GS23 18c 5.006 11.8 0.3262 11. 7 0.11129 1.156 1821 185 1820 98 1821 20.9 0 0 I9GS23 19c 3.565 9.1 0.2648 9.0 0.09765 1.002 1516 121 1542 71 1580 18.7 4 2 I9GS23 23c 2.961 9.6 0.2411 9.6 0.08905 1.036 1394 119 1397 72 1405 19.8 1 0 I9GS23 25c 3.449 10.1 0.2585 10. 0 0.09676 0.995 1483 132 1515 78 1563 18.6 5 2 I9GS23 27c 5.112 9.0 0.3263 9.0 0.11363 0.951 1822 141 1838 75 1858 17.2 2 1 I 9GS23 28c 11.435 9.0 0.4629 9.0 0.17918 0.959 2454 182 2559 82 2645 15.9 7 4 I9GS23 30c 2.181 9.4 0.1952 9.3 0.08101 1.194 1150 97 1175 64 1222 23.4 6 2 I9GS23 32c 4.184 8.5 0.3049 8.5 0.09953 0.684 1717 128 1671 69 1615 12.7 6 3

PAGE 44

44 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS23 33c 4.803 6.6 0.3237 6.5 0.10760 0.590 1809 103 1785 54 1759 10.8 3 1 I9GS23 34c 1.946 8.1 0.1880 8.0 0.07506 0.779 1111 82 1097 53 1070 15.6 4 1 I9GS23 35c 4.541 6.1 0.3027 6.1 0.10881 0.639 1706 91 1738 51 1780 11.6 4 2 I9GS23 37c 4.714 7.7 0.3283 7.6 0.10416 0.975 1831 121 1770 63 1700 17.9 8 3 I9GS23 38c 3.7 94 7.2 0.2766 7.2 0.09946 0.575 1576 100 1591 57 1614 10.7 2 1 I9GS23 43c 2.247 7.1 0.2052 7.1 0.07939 1.000 1204 77 1196 50 1182 19.7 2 1 I9GS23 44c 3.479 6.0 0.2534 6.0 0.09957 0.645 1457 78 1522 47 1616 12.0 10 4 I9GS23 48c 2.579 6.0 0.2190 6.0 0.0 8540 0.608 1278 70 1294 44 1325 11.8 4 1 I9GS23 49c 1.931 6.5 0.1802 6.4 0.07771 0.896 1069 63 1092 43 1139 17.8 6 2 I9GS23 50c 2.192 6.8 0.1939 6.6 0.08198 1.566 1144 69 1178 47 1245 30.6 8 3 I9GS23 51c 1.940 5.9 0.1844 5.8 0.07630 0.674 1092 59 1095 3 9 1103 13.5 1 0 I9GS23 53c 2.160 6.3 0.1980 6.2 0.07910 0.634 1166 66 1168 43 1175 12.5 1 0 I9GS23 54c 2.969 6.5 0.2422 6.5 0.08890 0.588 1399 81 1400 49 1402 11.3 0 0 I9GS23 55c 2.929 6.0 0.2347 6.0 0.09054 0.560 1360 73 1389 45 1437 10.7 5 2 I9GS23 5 7c 3.341 6.2 0.2579 6.1 0.09398 0.596 1480 81 1491 48 1508 11.2 2 1 I9GS23 58c 4.758 6.3 0.3203 6.3 0.10773 0.590 1793 98 1777 52 1761 10.8 2 1 I9GS23 59c 2.022 6.5 0.1868 6.3 0.07850 1.628 1105 64 1123 44 1160 32.2 5 2

PAGE 45

45 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS23 60c 8.325 6.1 0.4101 5.9 0.14721 1.753 2217 109 2267 55 2314 30.0 4 2 I9GS23 61c 3.001 6.0 0.2444 6.0 0.08906 0.573 1410 76 1408 45 1406 10.9 0 0 I9GS23 62c 2.705 6.0 0.2191 6.0 0.08954 0.639 1278 69 1330 44 1416 12.2 10 4 I9GS23 63c 3.647 6.1 0.2725 6.0 0.09708 0.592 1555 83 1560 48 1569 11.1 1 0 I9GS23 65c 3.571 6.0 0.2649 5.9 0.09778 0.766 1516 80 1543 47 1582 14.3 4 2 I9GS23 66c 1.601 6.2 0.1573 6.1 0.07381 0.977 943 54 971 38 1036 19.7 9 3 I9GS23 70c 2.981 5.9 0.2364 5.9 0.09144 0.578 1369 73 1403 45 1456 11.0 6 2 I9GS23 71c 2.980 6.0 0.2387 6.0 0.09054 0.577 1 381 74 1402 45 1437 11.0 4 2 I9GS23 72c 4.437 6.2 0.2976 6.1 0.10813 0.689 1681 90 1719 50 1768 12.6 5 2 I9GS23 73c 2.392 6.1 0.2087 6.1 0.08314 0.654 1223 67 1240 43 1272 12.7 4 1 I9GS23 74c 2.132 6.9 0.1928 6.8 0.08019 0.679 1138 71 1159 47 1202 13.4 5 2 I9GS23 75c 4.115 5.9 0.2788 5.9 0.10707 0.642 1586 83 1657 48 1750 11.7 9 4 I9GS23 79c 4.855 5.9 0.3089 5.9 0.11400 0.585 1737 89 1794 49 1864 10.5 7 3 I9GS23 80c 4.469 6.5 0.2953 6.5 0.10976 0.588 1669 95 1725 53 1795 10.7 7 3 I9GS24_ 4c 5.986 3.3 0.3554 3.1 0.12217 0.979 1962 53 1974 28 1988 17.4 1 1 I9GS24_ 5c 2.056 3.9 0.1845 3.6 0.08082 1.669 1092 36 1134 27 1217 32.8 10 4 I9GS24_ 6c 4.688 3.9 0.3132 3.8 0.10854 1.009 1758 58 1765 32 1775 18.4 1 0

PAGE 46

46 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS24_ 7c 4.609 3.8 0.3056 3.7 0.10938 0.993 1720 55 1751 31 1789 18.1 4 2 I9GS24_ 10c 4.536 3.6 0.3045 3.5 0.10804 0.998 1715 52 1737 30 1767 18.2 3 1 I9GS24_ 11c 2.053 3.5 0.1885 3.3 0.07900 1.179 1114 34 1133 24 1172 23.3 5 2 I9GS24_ 13c 2.112 3.6 0.1907 3.4 0.08034 1.131 1126 35 1153 25 1205 22.2 7 2 I9GS24_ 14c 4.602 3.6 0. 3075 3.5 0.10855 0.998 1730 53 1749 30 1775 18.2 3 1 I9GS24_ 15c 4.651 3.8 0.3115 3.6 0.10829 0.975 1749 56 1758 31 1771 17.8 1 0 I9GS24_ 16c 4.485 4.4 0.2999 4.3 0.10847 1.042 1692 63 1728 36 1774 19.0 5 2 I9GS24_ 18c 1.568 3.6 0.1615 3.4 0.07041 1.248 96 6 31 958 22 940 25.5 3 1 I9GS24_ 21c 2.125 3.5 0.1939 3.4 0.07951 1.013 1143 36 1157 24 1185 20.0 3 1 I9GS24_ 22c 1.731 4.0 0.1661 3.5 0.07560 1.882 991 32 1020 25 1085 37.7 9 3 I9GS24_ 28c 1.766 3.6 0.1740 3.4 0.07360 1.103 1035 33 1033 23 1031 22.3 0 0 I9GS24_ 30c 1.638 3.7 0.1640 3.5 0.07245 1.024 980 32 985 23 998 20.8 2 1 I9GS24_ 31c 1.642 3.4 0.1623 3.2 0.07337 1.118 971 29 986 22 1024 22.6 5 2 I9GS24_ 32c 3.752 3.9 0.2745 3.7 0.09913 1.041 1565 51 1582 31 1608 19.4 3 1 I9GS24_ 33c 4.066 3.3 0.2825 3.2 0.10439 1.001 1605 45 1647 27 1704 18.4 6 3 I9GS24_ 34c 1.994 3.4 0.1849 3.2 0.07819 1.280 1095 32 1113 23 1152 25.4 5 2 I9GS24_ 37c 3.608 3.6 0.2650 3.4 0.09874 1.105 1517 46 1551 28 1600 20.6 5 2

PAGE 47

47 Table 31. Continued Ratios Ages Samp le *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS24_ 40c 2.112 3.3 0.1949 3.1 0.07858 1.033 1149 33 1153 23 1162 20.4 1 0 I9GS24_ 42c 3.638 4.1 0.2630 4.0 0.10033 1.024 1506 54 1558 33 1630 19.0 8 3 I9GS24_ 49c 1.584 4.1 0.1584 3.9 0.07249 1.015 949 35 964 25 1000 20.6 5 2 I9GS24_ 51c 2.172 3.7 0.1934 3.5 0.08147 1.211 1141 36 1172 26 1233 23.7 7 3 I9GS24_ 53c 2.120 3.6 0.1 917 3.3 0.08018 1.316 1132 34 1155 25 1201 25.9 6 2 I9GS24_ 57c 2.049 3.3 0.1896 3.2 0.07839 1.043 1120 33 1132 23 1157 20.7 3 1 I9GS24_ 58c 3.694 3.5 0.2710 3.4 0.09886 0.994 1547 47 1570 28 1603 18.5 3 1 I9GS24_ 60c 1.743 3.4 0.1687 3.3 0.07491 1.040 100 6 30 1024 22 1066 20.9 6 2 I9GS24_ 61c 1.743 2.6 0.1716 2.5 0.07364 0.695 1022 24 1024 17 1032 14.0 1 0 I9GS24_ 62c 2.122 2.7 0.1951 2.6 0.07886 0.689 1150 28 1156 19 1169 13.6 2 0 I9GS24_ 66c 1.707 2.6 0.1696 2.5 0.07302 0.586 1010 24 1011 17 1014 11.9 0 0 I9GS24_ 67c 2.124 2.4 0.1956 2.3 0.07879 0.601 1152 25 1157 17 1167 11.9 1 0 I9GS24_ 68c 4.667 2.7 0.3110 2.6 0.10884 0.571 1747 40 1761 22 1780 10.4 2 1 I9GS24_ 69c 4.176 2.2 0.2792 2.1 0.10846 0.507 1589 29 1669 18 1774 9.2 10 5 I9GS24_ 72c 1.595 2.9 0 .1573 2.7 0.07351 1.261 943 23 968 18 1028 25.5 8 3 I9GS24_ 73c 3.207 2.5 0.2487 2.4 0.09354 0.709 1433 30 1459 19 1499 13.4 4 2 I9GS24_ 74c 1.663 2.5 0.1660 2.5 0.07267 0.555 991 23 994 16 1005 11.3 1 0

PAGE 48

48 Table 31. Continued Ratios Ages Sa mple *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS24_ 76c 5.048 2.8 0.3200 2.6 0.11440 0.755 1791 41 1827 23 1870 13.6 4 2 I9GS24_ 77c 4.958 2.7 0.3169 2.6 0.11347 0.629 1776 40 1812 22 1856 11.4 4 2 I9GS24_ 79c 3.678 2.7 0.2704 2.6 0.09864 0.783 1544 35 1566 21 1599 14.6 3 1 I9GS24_ 82c 2.038 2.8 0.1873 2.6 0.07892 1.071 1108 26 1128 19 1170 21.2 5 2 I9GS24_ 83c 2.133 2.7 0 .1946 2.6 0.07950 0.686 1147 28 1159 19 1185 13.5 3 1 I9GS24_ 86c 2.096 2.7 0.1900 2.5 0.08000 0.948 1122 26 1147 19 1197 18.7 6 2 I9GS24_ 88c 3.769 2.8 0.2750 2.7 0.09940 0.686 1567 38 1586 22 1613 12.8 3 1 I9GS24_ 90c 2.186 2.6 0.1983 2.5 0.07994 0.554 1 167 27 1176 18 1195 10.9 2 1 I9GS24_ 92c 4.685 2.5 0.3141 2.4 0.10815 0.551 1762 37 1764 21 1769 10.1 0 0 I9GS24_ 94c 4.642 2.5 0.3124 2.5 0.10775 0.562 1754 38 1757 21 1762 10.3 0 0 I9GS24_ 95c 2.337 2.5 0.2087 2.4 0.08122 0.525 1223 27 1224 18 1227 10.3 0 0 I9GS24_ 96c 1.660 2.5 0.1649 2.3 0.07301 0.851 985 21 993 16 1014 17.2 3 1 I9GS24_ 97c 3.854 2.5 0.2827 2.4 0.09889 0.525 1606 35 1604 20 1603 9.8 0 0 I9GS24_ 98c 2.173 2.7 0.1990 2.6 0.07920 0.706 1171 28 1172 19 1177 13.9 1 0 I9GS24_ 99c 2.179 2.7 0. 1983 2.6 0.07968 0.685 1167 28 1174 19 1189 13.5 2 1 I9GS24_ 101c 3.768 2.5 0.2778 2.4 0.09835 0.556 1582 34 1586 20 1593 10.4 1 0 I9GS24_ 102c 2.091 3.0 0.1889 2.9 0.08031 0.818 1116 30 1146 21 1205 16.1 7 3

PAGE 49

49 Table 31. Continued Ratios Ages Sample *207Pb/ 235 U *2 % error 206Pb/ 238 U 2 % err or 207Pb/ 206 Pb 2 % error 206Pb/ 238U (Ma) 2 error *207Pb/ 235U (Ma) *2 error 207Pb/ 206Pb (Ma) 2 error % 207Pb / 206Pb Disc % 207Pb/235 U Disc I9GS24_ 103c 2.055 2.7 0.1907 2.7 0.07814 0.692 1126 27 1134 19 1150 13.7 2 1 I9GS24_ 104c 4.613 3.2 0.3099 3.1 0.10798 0.572 1742 48 1751 27 1766 10.4 1 1 I9GS24_ 105c 2.079 2.8 0.1919 2.8 0.07858 0.653 1132 29 1142 19 1162 12.9 3 1 I9GS24_ 109c 1.919 2.8 0.1833 2.7 0.07595 0.594 1086 27 1088 18 1094 11.9 1 0 I9GS24_ 112c 2.491 2.5 0.2144 2.4 0.08429 0.718 1253 27 1269 18 1299 13.9 4 1 I9GS24_ 116c 4.591 3.0 0.3092 2.9 0.10769 0.524 1738 44 1747 25 1761 9.6 1 1 I9GS24_ 117c 4.562 2.6 0.3079 2.5 0.10747 0.563 1732 38 1742 21 1757 10.3 1 1 I9GS24_ 119c 3.664 2.5 0.2719 2.3 0.09773 0.723 1552 32 1563 19 1581 13.5 2 1 I9GS24_ 120c 2.174 2.6 0.1968 2.5 0.08015 0.799 1159 27 1173 18 1201 15.7 3 1

PAGE 50

50 Table 32. Marwar U Pb Isotopic Data Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb / 206Pb Disc % 207Pb / 235U Disc I9GS 4_4c 5.040 4.4 0.3169 4.3 0.1153 6 0.880 1776 66 1826 37 1886 15.8 6 3 I9GS 4_5c 10.621 4.2 0.4566 4.1 0.1686 9 0.876 2427 83 2490 39 2545 14.7 5 3 I9GS 4_7 c 1.337 4.6 0.1390 4.5 0.0697 8 1.119 839 35 862 27 922 23.0 9 3 I9GS 4_11c 4.627 4.1 0.3039 4.0 0.1104 5 0.903 1712 59 1754 34 1807 16.4 5 2 I9GS 4_11r 4.777 4.1 0.3143 4.0 0.1102 2 0.911 1763 62 1781 34 1803 16.5 2 1 I9GS 4_11r. 2 4.716 4.1 0.3096 3.9 0.1104 7 0.944 1740 60 1770 34 1807 17.1 4 2 I9GS 4_17c ore 4.605 4.3 0.3055 4.2 0.1093 1 0.946 1720 64 1750 36 1788 17.2 4 2 I9GS 4_17r 4.441 4.1 0.2959 4.0 0.1088 7 0.912 1672 59 1720 34 1781 16.6 6 3 I9GS 4_17r. 2 4.536 4.2 0.3025 4.1 0.1087 5 0.947 1705 61 1 737 34 1779 17.2 4 2 I9GS 4_23c 5.215 4.4 0.3317 4.4 0.1140 1 0.880 1848 70 1855 38 1864 15.9 1 0 I9GS 4_26c 4.402 4.2 0.3016 4.1 0.1058 8 0.864 1700 62 1713 35 1730 15.8 2 1 I9GS 4_28c 4.541 4.3 0.3039 4.2 0.1083 7 0.868 1712 63 1738 35 1772 15.8 3 2 I9G S 4_34c 3.856 4.4 0.2746 4.3 0.1018 3 0.877 1565 59 1604 35 1658 16.2 6 2 I9GS 4_36c 5.159 4.2 0.3263 4.1 0.1146 7 0.880 1822 65 1846 36 1875 15.8 3 1 I9GS 4_36r 4.928 5.0 0.3084 4.9 0.1159 1 0.897 1734 74 1807 41 1894 16.1 8 4

PAGE 51

51 Table 32. Continued Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc I9GS 4_40c 4.181 5.6 0.2839 5.5 0.1068 1 1.116 1612 78 1670 45 174 6 20.4 8 3 I9GS 4_41c 4.387 4.2 0.2976 4.1 0.1069 2 0.950 1681 60 1710 34 1748 17.4 4 2 I9GS 4_45c 4.418 4.1 0.3027 4.0 0.1058 6 0.886 1706 60 1715 34 1729 16.2 1 1 I9GS 4_46c 1.303 4.3 0.1382 4.1 0.0684 3 1.173 835 32 847 25 882 24.2 5 1 I9GS 4_46r 1.340 4.2 0.1399 4.0 0.0694 5 1.282 845 32 863 24 912 26.3 7 2 I9GS 4_49c 14.058 4.2 0.5164 4.1 0.1974 6 0.856 2686 90 2753 39 2805 14.0 4 2 I9GS 4_53c 4.346 4.3 0.2967 4.2 0.1062 4 0.874 1676 61 1702 35 1736 16.0 3 2 I9GS 4_55c 4.365 4.1 0.3002 4.0 0.1054 8 0.8 87 1693 59 1706 33 1723 16.3 2 1 I9GS 4_56c 3.641 4.3 0.2617 4.2 0.1008 9 0.923 1500 56 1558 34 1641 17.1 9 4 I9GS 4_58c 4.488 4.2 0.3002 4.1 0.1084 1 0.898 1694 61 1728 35 1773 16.4 4 2 I9GS 4_58r 4.483 4.2 0.3005 4.1 0.1082 0 0.891 1695 61 1728 34 1769 1 6.3 4 2 I9GS 4_60c 12.625 4.0 0.4952 3.9 0.1849 1 0.853 2595 84 2652 37 2697 14.1 4 2 I9GS 4_62r 12.287 4.6 0.4870 4.5 0.1829 6 0.796 2560 95 2626 42 2680 13.1 4 3 I9GS 4_64c 4.287 4.8 0.2942 4.7 0.1056 7 1.004 1664 69 1691 39 1726 18.4 4 2 I9GS 4_65c 6.5 61 4.4 0.3689 4.3 0.1289 9 0.828 2026 75 2054 38 2084 14.5 3 1 I9GS 4_67c 1.351 4.4 0.1407 4.2 0.0696 2 1.050 849 34 868 25 917 21.6 7 2 I9GS 4_68c 1.603 4.2 0.1593 4.1 0.0729 6 0.904 954 37 971 26 1013 18.3 6 2

PAGE 52

52 Table 32. Continued Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc I9GS 4_69c 1.121 4.4 0.1225 4.1 0.0663 5 1.410 745 29 763 23 818 29.4 9 2 I9GS 4_69r 1.124 4.4 0.1243 4 .3 0.0655 8 1.256 756 30 765 24 793 26.3 5 1 I9GS 4_71c 4.182 4.8 0.2796 4.7 0.1084 5 0.791 1591 66 1670 39 1774 14.4 10 5 I9GS 4_71r 4.225 4.4 0.2812 4.3 0.1089 5 0.803 1599 61 1679 36 1782 14.6 10 5 I9GS 4_74c 4.138 4.9 0.2782 4.8 0.1078 6 0.959 1584 67 1 662 40 1764 17.5 10 5 I9GS 4_76c 1.340 5.1 0.1386 4.8 0.0701 0 1.572 838 38 863 29 931 32.2 10 3 I9GS 4_78c 4.404 4.4 0.3011 4.2 0.1060 6 0.952 1698 63 1713 36 1733 17.4 2 1 I9GS 4_85c 4.303 4.3 0.2955 4.2 0.1056 2 0.908 1670 62 1694 35 1725 16.6 3 1 I9GS 4_86c 4.893 4.8 0.3081 4.7 0.1151 6 0.862 1733 71 1801 40 1882 15.5 8 4 I9GS 4_88c 1.381 4.6 0.1444 4.4 0.0693 6 1.475 870 35 881 27 909 30.3 4 1 I9GS 4_90c 13.422 4.4 0.5038 4.3 0.1932 1 0.799 2632 92 2709 41 2770 13.1 5 3 I9GS 4_90r 13.109 4.5 0.5002 4. 4 0.1900 9 0.829 2617 95 2687 42 2743 13.6 5 3 I9GS 4_92c 8.422 4.5 0.4149 4.5 0.1472 2 0.817 2239 84 2277 41 2314 14.0 3 2 I9GS 4_93c 8.513 4.3 0.4191 4.3 0.1473 3 0.798 2258 81 2287 39 2315 13.7 2 1 I9GS 4_94c 1.639 4.4 0.1600 4.3 0.0742 9 0.932 958 38 98 5 28 1049 18.8 9 3 I9GS 4_95c 4.289 4.7 0.2851 4.5 0.1091 4 1.268 1618 65 1691 38 1785 23.1 9 4 I9GS5 3c 4.040 6.5 0.2857 6.5 0.1025 4 0.715 1622 92 1642 52 1671 13.2 3 1

PAGE 53

53 Table 32. Continued Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc I9GS5 5c 1.406 5.6 0.1443 5.5 0.0706 8 1.375 870 44 891 33 948 28.1 8 2 I9GS5 13c 4.246 5.7 0.2917 5.7 0.1055 9 0.500 1651 83 1683 46 1725 9.2 4 2 I9GS5 14c 2.407 7.2 0.2144 6.6 0.0814 3 2.813 1253 75 1244 51 1232 55.1 2 1 I9GS5 15c 4.432 5.7 0.3021 5.6 0.1064 1 0.507 1703 84 1718 46 1739 9.3 2 1 I9GS5 19c 2.913 6.9 0.2353 5.8 0.0898 2 3.838 1363 71 1385 52 1422 73.2 4 2 I 9GS5 20c 4.885 6.5 0.3168 6.4 0.1118 2 0.841 1776 99 1799 54 1829 15.2 3 1 I9GS5 21c 1.198 7.2 0.1327 7.1 0.0655 1 0.714 804 54 800 39 791 15.0 2 1 I9GS5 28c 1.302 6.7 0.1382 6.6 0.0683 2 1.113 835 52 847 38 878 23.0 5 1 I9GS5 29c 1.391 6.8 0.1441 6.7 0. 0699 8 1.044 869 55 885 40 928 21.4 6 2 I9GS5 30c 5.213 6.8 0.3191 6.7 0.1184 7 0.704 1787 104 1854 57 1933 12.6 8 4 I9GS5 31c 5.305 7.0 0.3380 7.0 0.1138 5 0.666 1878 113 1869 59 1862 12.0 1 0 I9GS5 32c 4.810 6.8 0.3137 6.7 0.1111 9 1.049 1761 103 1786 56 1819 19.0 3 1 I9GS5 33c 1.189 6.9 0.1325 6.9 0.0650 9 0.780 803 52 795 38 777 16.4 3 1 I9GS5 34c 1.364 6.7 0.1435 6.7 0.0689 1 0.979 865 54 873 39 896 20.2 3 1 I9GS5 38c 1.214 7.0 0.1313 6.9 0.0670 5 1.020 796 52 807 38 839 21.2 5 1 I9GS5 40c 5.293 6.7 0.3398 6.6 0.1129 8 0.853 1887 108 1867 56 1848 15.4 2 1 I9GS5 41c 4.889 7.1 0.3197 7.0 0.1109 3 1.132 1789 109 1800 59 1815 20.5 1 1

PAGE 54

54 Table 32. Continued Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206P b/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc I9GS5 42c 5.400 7.0 0.3403 7.0 0.1150 9 0.687 1889 114 1885 59 1881 12.4 0 0 I9GS5 43c 4.533 6.7 0.3117 6.7 0.1054 9 0.691 1750 102 1737 55 1723 12.7 2 1 I9GS5 44c 4.466 9.2 0.2896 9.1 0.1118 5 1.142 1641 131 1724 75 1830 20.7 10 5 I9GS5 45c 4.726 6.9 0.3127 6.8 0.1096 0 0.676 1756 105 1772 57 1793 12.3 2 1 I9GS5 46c 4.720 7.2 0.3147 7.1 0.1087 7 0.815 1765 110 1770 59 1779 14.8 1 0 I9GS5 48c 4.694 6.9 0.30 83 6.9 0.1104 1 0.703 1734 104 1766 57 1806 12.8 4 2 I9GS5 50c 4.922 7.2 0.3181 7.1 0.1122 3 1.091 1782 110 1806 60 1836 19.7 3 1 I9GS5 51c 2.185 6.6 0.1954 6.6 0.0810 8 0.739 1152 69 1176 45 1223 14.5 6 2 I9GS5 52c 1.390 6.9 0.1465 6.8 0.0688 2 0.804 882 5 6 885 40 893 16.6 1 0 19GS 6_1c 1.180 3.7 0.1293 3.1 0.0662 2 1.921 784 23 791 20 813 40.1 4 1 19GS 6_4c 3.986 3.8 0.2759 3.3 0.1047 8 1.888 1572 47 1631 31 1710 34.7 8 4 I9GS 6_6c 5.012 3.8 0.3188 3.3 0.1140 2 1.858 1785 52 1821 32 1864 33.5 4 2 I9GS 6_7 c 5.181 3.8 0.3306 3.3 0.1136 6 1.879 1843 53 1849 32 1859 33.9 1 0 I9GS 6_9c 4.268 4.1 0.2971 3.6 0.1041 8 1.873 1678 54 1687 33 1700 34.5 1 1 I9GS 6_9r 4.015 3.8 0.2780 3.3 0.1047 6 1.861 1583 47 1637 31 1710 34.2 7 3 I9GS 6_13c 1.339 3.9 0.1428 3.5 0.06 80 1 1.878 861 28 863 23 869 38.9 1 0 I9GS 6_13r 1.345 3.8 0.1435 3.3 0.0679 6 1.878 865 27 865 22 867 38.9 0 0

PAGE 55

55 Table 32. Continued Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc 19GS 6_23c 4.829 5.1 0.3047 3.8 0.1149 7 3.472 1716 57 1790 43 1879 62.5 9 4 I9GS 6_25c 21.283 3.9 0.5926 3.4 0.2604 6 1.856 3003 81 3151 37 3249 29.2 8 5 I9GS 6_25r 21.700 3.7 0.60 14 3.2 0.2617 2 1.855 3038 78 3170 36 3257 29.2 7 4 I9GS 6_25r. 2 22.150 3.6 0.6126 3.1 0.2622 2 1.854 3083 77 3190 35 3260 29.1 5 3 I9GS 6_34c 4.677 3.8 0.3056 3.3 0.1110 1 1.998 1720 49 1763 32 1816 36.2 5 2 I9GS 6_39c 4.216 4.0 0.2882 3.5 0.1061 0 1.862 1 634 51 1677 32 1734 34.1 6 3 I9GS 6_39r 4.300 4.0 0.2935 3.5 0.1062 8 1.866 1660 51 1693 32 1737 34.2 4 2 I9GS 6_45c 1.317 2.9 0.1386 2.8 0.0689 0 0.569 838 22 853 17 896 11.7 6 2 I9GS 6_51c 4.952 2.8 0.3165 2.8 0.1135 0 0.432 1774 43 1811 23 1856 7.8 4 2 I9GS 6_53c 4.744 2.8 0.3055 2.8 0.1126 3 0.392 1720 42 1775 23 1842 7.1 7 3 I9GS 6_59c 1.107 3.3 0.1231 3.3 0.0652 5 0.593 749 23 757 18 783 12.4 4 1 I9GS 6_60c 1.119 3.0 0.1245 2.9 0.0652 4 0.593 757 21 763 16 782 12.4 3 1 I9GS 6_64c 20.186 2.9 0.5807 2. 9 0.2521 1 0.331 2954 69 3100 28 3198 5.2 8 5 2011G S19_1 c 4.366 5.1 0.3029 5.0 0.1045 4 1.017 1707 75 1706 42 1706 18.7 0 0 2011G S19_1r 4.420 5.1 0.3078 5.0 0.1041 5 0.992 1731 76 1716 42 1699 18.2 2 1

PAGE 56

56 Table 32. Continued Ratios Ages Samp l e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc 2011G S19_3 c 1.242 5.1 0.1364 5.0 0.0660 1 1.036 825 39 819 29 807 21.7 2 1 2011G S19_4 c 1.208 5.3 0.1319 5.2 0.0664 0 1.048 800 39 804 29 819 21.9 2 1 2011G S19_1 1c 5.177 5.7 0.3175 5.3 0.1182 6 2.324 1779 81 1849 48 1930 41.6 8 4 2011G S19_1 2c 10.899 4.8 0.4779 4.7 0.1654 2 0.991 2520 97 2514 44 2512 16.6 0 0 2011G S19_2 5c 4.774 6.3 0.3208 6.2 0.1079 3 0.984 1795 97 1780 52 1765 18.0 2 1 2011G S19_2 5r 4.300 7.4 0.2867 7.3 0.1087 9 1.049 1626 104 1693 60 1779 19.1 9 4 2011G S19_4 7r 4.317 6.3 0.2980 6.2 0.1050 6 0.972 1683 91 1696 51 1715 17.8 2 1 2011G S19_4 7r.2 4.201 5.2 0.2904 5.1 0.1049 2 0.981 1645 74 1674 42 1713 18.0 4 2 2011G S19_4 7r.3 4.737 4.4 0.3284 4.3 0.1046 3 0.968 1832 69 1774 37 1708 17.8 7 3 2011G S19_4 7r.4 5.135 8.0 0.3171 6.4 0.1174 4 4.899 1777 99 1842 67 1918 87.7 7 4 2011G S19_4 7c 4.444 4.5 0.3090 4.4 0.1043 0 0.962 1737 67 1720 37 1702 17.7 2 1

PAGE 57

57 Table 32. Continued Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc 2011G S19_5 1c 18.292 5.3 0.5549 4.1 0.2390 9 3.288 2848 94 3005 50 3114 52.3 9 5 2011G S19_6 3r 4.730 4.7 0.3099 4.6 0.1107 0 0.946 1742 70 1772 39 1811 17.2 4 2 2011G S19_6 3c 4.909 5.1 0.3236 5.0 0.1100 3 0.667 1809 79 1803 42 1800 12.1 1 0 2011G S19_6 3c.2 5.075 5.3 0.3350 5.3 0.1098 6 0.626 1864 85 1832 45 1797 11.4 4 2 2011G S19_6 3r 4.816 4.2 0.3193 4.1 0.1093 8 0.938 1788 64 1787 35 1789 17.1 0 0 2011G S19_6 3r 4.796 4.2 0.3169 4.1 0.1097 7 0.541 1776 64 1784 35 1796 9.8 1 0 2011G S19_6 3r 4.643 7.5 0.3072 7.4 0.1096 4 0.614 1728 112 1757 61 1793 11.2 4 2 2011G S19_8 6c 23.847 6.4 0.6644 6.3 0.2603 3 1.065 3287 16 1 3262 61 3249 16.7 1 1 2011G S19_8 7r 20.212 12.9 0.5824 12.8 0.2517 1 0.823 2961 302 3101 121 3196 13.0 7 5 2011G S19_9 2c 90.326 34.5 0.9390 34.1 0.6976 6 5.129 4272 1025 4583 320 4600 80.8 7 7 2011G S19_9 5r 9.818 9.2 0.4389 9.2 0.1622 5 0.674 2348 180 241 7 83 2479 11.3 5 3

PAGE 58

58 Table 32. Continued Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc 2011G S19_9 5c 10.282 5.5 0.4625 5.5 0.1612 5 0.505 2452 111 2460 50 2469 8.5 1 0 2011G S19_9 5c.2 10.504 4 .5 0.4715 4.5 0.1615 7 0.498 2492 92 2480 41 2472 8.4 1 0 2011G S19_9 5r 10.127 5.6 0.4524 5.6 0.1623 6 0.693 2408 111 2446 51 2480 11.7 3 2 2011G S19_9 5r 10.006 3.7 0.4525 3.6 0.1603 9 0.483 2408 73 2435 34 2460 8.1 2 1 2011G S19_9 9c 1.274 4.7 0.1382 4.6 0.0668 3 0.770 835 36 834 26 832 16.0 0 0 2011G 19_10 7c 1.763 5.1 0.1683 4.6 0.0759 7 2.199 1004 43 1032 33 1094 44.0 8 3 2011G 19_11 0c 1.061 4.9 0.1187 4.8 0.0648 4 0.734 724 33 734 25 769 15.4 6 1 2011G S19_1 14r 1.660 4.9 0.1655 4.8 0.0727 8 0.948 988 44 993 31 1008 19.2 2 1 2011G S19_1 14r.2 1.693 5.9 0.1642 5.5 0.0747 9 2.068 981 50 1006 37 1063 41.5 8 2 2011G S19_1 18c 1.136 5.7 0.1262 5.7 0.0652 7 0.612 767 41 770 30 783 12.8 2 0 2011G S19_1 20c 4.380 8.2 0.2889 8.0 0.1099 3 1.553 1638 116 1708 66 1798 28.2 9 4

PAGE 59

59 T able 32. Continued Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc 2011G S19_1 20r 4.750 5.5 0.3129 5.4 0.1101 1 1.433 1756 82 1776 46 1801 26.0 2 1 2011G S19_1 30r 3.713 8.2 0.2652 7.7 0.1015 3 2.846 1518 104 1574 65 1652 52.7 8 4 2011G S19_1 30c 4.333 5.8 0.2880 5.5 0.1091 1 1.905 1633 79 1699 47 1785 34.7 8 4 2011G S19_1 33c 4.559 6.8 0.3110 6.6 0.1063 3 1.528 1747 101 1742 56 1738 28.0 1 0 2011G S19_1 42c 5.391 6.2 0.3379 6.0 0 .1157 2 1.506 1878 98 1883 53 1891 27.1 1 0 2011G S19_1 75c 5.095 5.6 0.3377 5.5 0.1094 2 1.403 1877 89 1835 47 1790 25.5 5 2 2011G S19_1 75r 4.656 6.9 0.3074 6.8 0.1098 5 1.503 1729 102 1759 57 1797 27.3 4 2 2011G S19_1 75c 5.118 5.4 0.3399 5.3 0.1092 0 1.394 1888 86 1839 46 1786 25.4 6 3 2011G S19_1 84c 22.357 339.2 0.6796 240.0 0.2385 9 239.67 2 3346 5107 3199 1958 3111 3810.5 8 5 2011G S19_1 85c 24.772 339.1 0.7131 239.9 0.2519 7 239.67 2 3473 5225 3299 1963 3197 3784.1 9 5 2011G S19_1 86c 25.496 339.1 0.7273 239.9 0.2542 4 239.67 1 3526 5275 3327 1965 3211 3780.3 10 6

PAGE 60

60 Table 32. Continued Ratios Ages Sampl e 207Pb/ 235 U (%) 206Pb/ 238 U (%) 207Pb/ 206 Pb (%) 206Pb/ 238U (Ma) 207Pb/ 235U (Ma) 207Pb/ 206Pb (Ma) % 207Pb/ 206Pb Disc % 207Pb/ 235U Disc G113 4c 1.356 7.2 0.1419 4.6 0.0693 5 5.491 856 37 870 42 909 112.9 6 2 G113 14c 1.336 7.5 0.1401 4.8 0 .0691 2 5.753 846 38 861 43 902 118.5 6 2 G113 18c 1.312 6.8 0.1401 4.0 0.0679 2 5.552 846 32 851 39 866 115.0 2 1 G113 23c 4.362 7.0 0.3078 4.3 0.1027 9 5.533 1731 65 1705 57 1675 102.1 3 2 G113 27c 4.584 6.8 0.3182 4.1 0.1044 9 5.483 1782 63 1746 56 170 5 100.8 5 2 G113 48c 1.604 7.3 0.1596 4.6 0.0728 7 5.709 956 41 972 45 1010 115.6 5 2 G113 52c 4.779 7.5 0.3138 5.1 0.1104 4 5.493 1761 79 1781 62 1807 99.7 3 1 G113 58c 1.309 7.5 0.1401 4.5 0.0677 4 6.039 846 35 850 43 861 125.2 2 0 G113 61c 1.261 9.4 0.1352 7.3 0.0676 3 5.921 818 56 828 53 857 122.8 5 1 G113 69c 1.419 10.1 0.1508 7.9 0.0682 5 6.241 906 67 897 59 876 129.0 3 1 G113 71c 4.892 9.2 0.3357 7.1 0.1056 9 5.862 1867 115 1801 76 1726 107.5 8 4 G113 72c 1.349 11.1 0.1435 7.4 0.0681 9 8.333 86 5 60 867 64 874 172.3 1 0 G113 79c 1.556 10.5 0.1550 8.2 0.0728 1 6.535 930 71 953 64 1009 132.4 8 2

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61 Table 3 3 Hf Isotopic Data Sample # 176Hf / 177Hf uncorr. 176Hf /177Hf corr. error (+/ ) Hf (V) 175 Lu (V) 172 Yb (V) 176 Lu/ 177Hf measured and mass biased corrected 176Hf/ 177Hf init ial Model Age (CHUR) By Model Age (DM) By 176/ 177Hf (CHUR) T % corr I9GS4 11 0.32718 0.281613 0.000018 41 1.20 0.008 0.018 0.00088 0.281583 1.89 2.26 0.281633 1.8 14 I9GS4 17 0.28 646 0.281493 0.000018 45 1.19 0.001 0.002 0.00008 0.281490 2.03 2.37 0.281650 5.7 2 I9GS4 23 0.31382 0.281498 0.000026 45 1.00 0.004 0.011 0.00059 0.281477 2.05 2.40 0.281596 4.2 10 I9GS4 26 0.30480 0.281526 0.00003 4 4 0.98 0.003 0.007 0.00044 0.281511 2.00 2.35 0.281682 6.1 8 I9GS4 27 0.31447 0.281489 0.000026 45 0.77 0.004 0.008 0.00063 0.281468 2.07 2.41 0.281684 7.7 10 I9GS4 28 0.31328 0.281623 0.000034 40 0.92 0.004 0.009 0.00059 0.281603 1.85 2.23 0.281654 1.8 10 I9GS4 32 0.34739 0.281455 0.000027 46 0.92 0.007 0.020 0.00107 0.281418 2.15 2.49 0.281637 7.8 19 I9GS4 34 0.30891 0.281461 0.000041 46 0.86 0.003 0.008 0.00052 0.281444 2.11 2.44 0.281700 9.1 9 I9GS4 36 0.33351 0.281614 0.000018 41 1.07 0. 008 0.018 0.00097 0.281580 1.89 2.26 0.281590 0.4 16 I9GS4 41 0.31978 0.281527 0.000032 44 0.70 0.004 0.009 0.00070 0.281504 2.01 2.37 0.281672 6.0 12 I9GS4 45 0.33865 0.281674 0.000044 38 0.75 0.006 0.014 0.00104 0.281639 1.80 2.18 0.281670 1.1 17 I9GS4 53 0.29846 0.281412 0.000039 48 0.84 0.002 0.005 0.00036 0.281400 2.17 2.50 0.281679 9.9 6 I9GS4 58 0.29869 0.281646 0.000024 39 0.73 0.002 0.004 0.00033 0.281635 1.80 2.18 0.281655 0.7 6 I9GS4 71 0.32271 0.281499 0.000024 45 0.97 0.005 0.013 0.00071 0.281475 2.06 2.40 0.281654 6.4 13 I9GS4 86 0.32118 0.28134 0.000027 50 0.98 0.005 0.013 0.00071 0.281315 2.31 2.62 0.281585 9.6 12 I9GS4 95 0.32074 0.281487 0.000027 45 0.80 0.004 0.011 0.00071 0.281463 2.08 2.42 0.281647 6.5 12 I9GS5_3 0 .32832 0.281627 0.000027 40 3.63 0.027 0.049 0.00119 0.281589 1.88 2.26 0.281721 4.7 14 I9GS5_13 0.36518 0.281564 0.000023 42 4.64 0.053 0.117 0.00176 0.281506 2.02 2.38 0.281686 6.4 23 I9GS5_15 0.33977 0.28147 0.000014 46 4.74 0.040 0.088 0.00116 0 .281432 2.13 2.47 0.281677 8.7 17 I9GS5_20 0.32004 0.281449 0.000014 46 3.46 0.022 0.047 0.00080 0.281421 2.14 2.48 0.281619 7.0 12 I9GS5_31 0.47335 0.281955 0.000018 28 2.60 0.093 0.158 0.00482 0.281784 1.52 1.99 0.281598 6.6 40 I9GS5_32 0.29754 0. 2815 0.0000079 45 4.22 0.012 0.023 0.00035 0.281488 2.03 2.38 0.281625 4.9 5 I9GS5_40 0.30088 0.281334 0.000013 50 3.73 0.011 0.023 0.00038 0.281321 2.30 2.61 0.281607 10.2 6 I9GS5_41 0.35325 0.28155 0.000014 43 4.55 0.049 0.113 0.00143 0.281501 2.0 2 2.38 0.281628 4.5 20 I9GS5_42 0.35924 0.281525 0.000015 44 3.86 0.047 0.097 0.00154 0.281520 2.07 2.42 0.282655 40.2 22 I9GS5_43 0.35862 0.281355 0.000022 50 4.07 0.045 0.090 0.00173 0.281298 2.36 2.67 0.281687 13.8 22 I9GS5_44 0.31620 0.281655 0 .000022 39 4.76 0.024 0.052 0.00068 0.281631 1.81 2.19 0.281618 0.5 11 I9GS5_45 0.30918 0.281508 0.00002 44 4.56 0.017 0.040 0.00056 0.281489 2.04 2.38 0.281642 5.4 9 I9GS5_46 0.30298 0.281695 0.000028 38 4.82 0.021 0.031 0.00066 0.281673 1.74 2.13 0 .281651 0.8 7 I9GS5_47 0.33023 0.281505 0.000015 44 4.41 0.031 0.068 0.00095 0.281473 2.06 2.41 0.281647 6.2 15 I9GS5_48 0.28527 0.281488 0.000011 45 4.39 0.002 0.005 0.00007 0.281486 2.04 2.38 0.281633 5.2 1 I9GS5_50 0.30419 0.281611 0.000013 41 3 .69 0.012 0.027 0.00041 0.281597 1.86 2.23 0.281615 0.6 7 I9GS6 4 0.29932 0.281593 0.000021 41 1.10 0.003 0.006 0.00033 0.281582 1.89 2.25 0.281695 4.0 6 I9GS6 7 0.34183 0.281674 0.00003 38 0.98 0.008 0.020 0.00108 0.281636 1.80 2.19 0.281596 1.4 18 I9GS6 9 0.36075 0.28161 0.000034 41 1.02 0.010 0.027 0.00133 0.281567 1.92 2.29 0.281702 4.8 22 I9GS6 23 0.29899 0.28155 0.000021 43 1.17 0.003 0.007 0.00031 0.281539 1.95 2.31 0.281587 1.7 6 I9GS6 34 0.28899 0.281541 0.000015 43 1.25 0.002 0.003 0 .00016 0.281536 1.96 2.31 0.281627 3.3 3 I9GS6 39 0.32450 0.281581 0.000024 42 1.40 0.008 0.020 0.00074 0.281557 1.93 2.29 0.281680 4.4 13 G113_27 0.29659 0.281573 0.00002 42 4.24 0.008 0.019 0.00027 0.281564 1.92 2.28 0.281698 4.7 5

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62 Table 33 Cont inued Sample # 176Hf/ 177Hf uncorr. 176Hf/177Hf corr. error (+/ ) Hf (V) 175Lu (V) 172Yb (V) 176Lu/ 177Hf measured and mass biased corrected 176Hf/ 177Hf initial Model Age (CHUR) By Model Age (DM) By 176/ 177Hf (CHUR) T % corr G113_52 0.32599 0.281548 0.000014 43 4.41 0.029 0.059 0.00089 0.281518 1.99 2.35 0.281633 4.1 14 G113_71 0.36007 0.281504 0.000015 44 4.12 0.048 0.104 0.00161 0.281451 2.11 2.46 0.281685 8.3 22 2011GS19 1 0.33863 0.281428 0.000013 47 3.55 0.030 0.065 0.00115 0.281391 2.20 2.53 0.281698 10.9 17 2011GS19 25 0.32922 0.281546 0.000 015 43 4.90 0.034 0.072 0.00096 0.281514 2.00 2.36 0.281660 5.2 14 2011GS19 47 0.30953 0.281503 0.000015 44 4.88 0.021 0.044 0.00059 0.281484 2.04 2.39 0.281678 6.9 9 2011GS19 63 0.32975 0.281616 0.000011 40 4.00 0.030 0.061 0.00105 0.281579 1.89 2. 26 0.281608 1.0 15 2011GS19 78 0.36158 0.281725 0.000011 37 3.12 0.041 0.078 0.00182 0.281663 1.76 2.16 0.281636 0.9 22 2011GS19 120 0.29616 0.281486 0.000021 45 5.43 0.010 0.023 0.00026 0.281477 2.05 2.39 0.281639 5.7 5 2011GS19 130 0.29831 0.28149 7 0.000013 45 3.96 0.012 0.021 0.00039 0.281484 2.04 2.39 0.281647 5.8 6 2011GS19 133 0.33519 0.281473 0.0000084 45 4.07 0.033 0.070 0.00109 0.281437 2.12 2.46 0.281677 8.5 16 2011GS19 142 0.43165 0.281538 0.000013 43 5.07 0.113 0.235 0.00314 0.2814 25 2.15 2.51 0.281579 5.5 35 2011GS19 175 0.31603 0.281522 0.000013 44 4.63 0.021 0.051 0.00060 0.281501 2.02 2.37 0.281644 5.1 11 I9GS14 3 0.32745 0.281554 0.000023 43 3.76 0.026 0.054 0.00096 0.281522 1.99 2.34 0.281648 4.5 14 I9GS14 26 0.34580 0 .281571 0.000026 42 2.93 0.030 0.059 0.00144 0.281522 1.99 2.35 0.281644 4.3 19 I9GS14 43 0.31279 0.281431 0.000019 47 4.13 0.021 0.041 0.00067 0.281408 2.16 2.49 0.281632 7.9 10 I9GS14 52 0.32965 0.281596 0.000017 41 3.97 0.029 0.063 0.00099 0.2815 63 1.92 2.29 0.281654 3.2 15 I9GS14 56 0.32854 0.281415 0.000016 48 3.68 0.027 0.055 0.00099 0.281382 2.21 2.54 0.281679 10.5 14 I9GS14 77 0.31078 0.28155 0.000017 43 3.37 0.015 0.033 0.00061 0.281529 1.97 2.33 0.281645 4.1 9 I9GS14 78 0.33528 0.28 1558 0.00001 42 4.13 0.034 0.073 0.00110 0.281521 1.99 2.35 0.281654 4.7 16 I9GS16 22 0.33006 0.281417 0.000041 47 0.66 0.004 0.011 0.00084 0.281400 2.20 2.52 0.281600 7.1 15 I9GS16 36 0.32041 0.28172 0.000025 37 0.82 0.005 0.011 0.00085 0.281703 1. 71 2.11 0.281652 1.8 12 I9GS17_58 0.3032 3 0.28139 0.000036 48 0.82 0.003 0.006 0.00044 0.281375 2.21 2.53 0.281613 8.5 7 I9GS20_11 0.30111 0.281504 0.000031 44 0.95 0.003 0.006 0.00052 0.281486 2.04 2.39 0.281596 3.9 7 I9GS20_23 0.30801 0.281755 0.0 00019 36 1.11 0.005 0.009 0.00069 0.281732 1.65 2.05 0.281674 2.0 9 I9GS20_27 0.32498 0.281591 0.000021 41 1.49 0.014 0.021 0.00134 0.281545 1.95 2.32 0.281638 3.3 13 I9GS20_32 0.34412 0.281449 0.000025 46 1.95 0.022 0.039 0.00159 0.281393 2.20 2.53 0.281595 7.2 18 I9GS20_39 0.29826 0.281598 0.000023 41 1.30 0.004 0.007 0.00043 0.281584 1.89 2.25 0.281667 3.0 6 I9GS20_62 0.31998 0.281514 0.000021 44 1.55 0.008 0.019 0.00073 0.281490 2.04 2.39 0.281685 6.9 12 I9GS20_64 0.36568 0.281554 0.000016 43 1.93 0.021 0.053 0.00146 0.281503 2.02 2.38 0.281613 3.9 23 I9GS20_73 0.33996 0.281553 0.000016 43 1.76 0.014 0.033 0.00113 0.281513 2.00 2.36 0.281601 3.1 17 I9GS20_79 0.30426 0.281606 0.000023 41 1.53 0.005 0.011 0.00041 0.281592 1.87 2.24 0.2 81597 0.2 7 I9GS20_81 0.37605 0.281728 0.000016 36 1.29 0.018 0.041 0.00184 0.281665 1.75 2.16 0.281645 0.7 25 I9GS23 33 0.31512 0.281607 0.000083 41 2.30 0.016 0.025 0.00093 0.281576 1.90 2.27 0.281664 3.1 11 I9GS23 58 0.34455 0.281555 0.000017 43 4.35 0.047 0.089 0.00139 0.281509 2.01 2.37 0.281662 5.5 18 I9GS23 5 0.34206 0.28156 0.000025 42 4.09 0.036 0.079 0.00119 0.281520 1.99 2.35 0.281655 4.8 18 I9GS23 27 0.34131 0.281461 0.00003 46 3.38 0.040 0.064 0.00162 0.281404 2.18 2.52 0.281600 7.0 18 I9GS24 92 0.32313 0.281651 0.000023 39 1.01 0.006 0.014 0.00080 0.281624 1.82 2.20 0.281658 1.2 13 I9GS24 94 0.32603 0.281617 0.000028 40 1.03 0.007 0.016 0.00088 0.281600 1.88 2.25 0.281662 2.2 14 I9GS24 104 0.31677 0.281606 0.000025 41 0.8 1 0.004 0.010 0.00064 0.281593 1.88 2.25 0.281659 2.4 11

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63 Table 33 Continued Sample # 176Hf/ 177Hf uncorr. 176Hf/177Hf corr. error (+/ ) Hf (V) 175Lu (V) 172Yb (V) 176Lu/ 177Hf measured and mass biased corrected 176Hf/ 177Hf initial Model Age (CHUR) By Model Age (DM) By 176/ 177Hf (CHUR) T % corr I9GS24 116 0.34976 0.28161 0.000026 41 1.13 0.010 0.024 0.00127 0.281610 1.91 2.2 9 0.281663 1.9 19 I9GS24 6 0.3203 9 0.281534 0.000032 43 0.63 0.004 0.008 0.00078 0.281508 2.01 2.36 0.281653 5.2 12 I9GS24 7 0.35807 0.281691 0.000049 38 0.75 0.006 0.019 0.00142 0.281662 1.79 2.18 0.281644 0.6 21 I9GS24 10 0.30978 0.281543 0.000029 43 1.04 0.004 0.009 0.00058 0.281543 1.98 2.34 0.281659 4.1 9 I9GS24 14 0.32114 0.281604 0.000028 41 1.03 0.006 0.013 0.00075 0.281604 1.89 2.26 0.281653 1.8 12 I9GS24 15 0.32243 0.281766 0.000045 35 0.93 0.005 0.012 0.00081 0.281749 1.64 2.05 0.28 1656 3.3 13 I9GS24 16 0.33389 0.281541 0.000035 43 0.97 0.007 0.017 0.00101 0.281507 2.01 2.37 0.281654 5.2 16 I9GS24 33 0.31397 0.281834 0.000036 33 1.45 0.007 0.015 0.00061 0.281823 1.52 1.94 0.281699 4.4 10 I9GS24 59 0.33679 0.281682 0.000024 38 1.16 0.009 0.021 0.00105 0.281660 1.79 2.17 0.281654 0.2 16 I9GS24 68 0.339 91 0.281527 0.000038 44 1.75 0.012 0.032 0.00097 0.281488 2.03 2.38 0.281650 5.7 17 I9GS24 69 0.45806 0.281548 0.000031 43 1.01 0.021 0.057 0.00295 0.281484 2.12 2.48 0.281654 6.1 39 I9GS24 76 0.30231 0.281388 0.000025 48 1.18 0.004 0.008 0.00039 0.281380 2.21 2.53 0.281592 7.5 7

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64 Figure 31 Detrital zircon probability plots for the select samples from the Son Valley (Kaimur, Rewa/Kaimur, Rewa and Bhander Sandstone) Sect or and Rajasthan (Bhander Great Boundary Fault Sandstone and Bundi Bhander Sandstone) Sector Upper Vindhyan units. Comparisons between this figure and figure 6 show that Marwar and upper Vindhyan samples can no longer be correlated, strengthening the argum ents by Malone et al. (2008) and McKenzie et al. (2011).

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65 Figure 32 Detrital Zircon probability plots for select samples from the Marwar Supergroup. Note the appearance of <1000 Ma zircons in these plots compared to upper Vindhyan plots that contain no zircons <1000 Ma

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66 Figure 33 Pb age data for ~1.71.8 Ga detrital zircons from both the Marwar and upper Vindhyan sediments. These zircons also correlate well s amples from the Aravalli Mountain Range seen in the study by Kaur et al. (2012), represented by the red shaded cloud. This suggests that ~1.71.8 Ga detrital zircons found in both the Marwar and Upper Vindhyan sediments may owe their source to the Aravalli region.

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67 CHAPTER 4 DISCUSSION Marwar and Vindhyan Correlations Figure 41 shows a complete compilation of detrital zircon data from the Marwar and Vindhyan basins based on new data reported herein along with data from Malone et al. (2008) and McKenzie et al. (2011) Data from these three studies are striking in that there is a complete absence of detrital zircons <1000 Ma throughout upper Vindhyan sediments in contrast to the Marwar Supergroup that contains abundant detrital zircons in the 700 900 Ma ran ge The difference in the zircon populations between the two basins can have multiple causes. The two basins may have evolved contemporaneously, but have different source regions or were separated by a physiographic barrier such as the Great Boundary Fault ( Figure 12 ) The basins may have evolved at different times as reflected in the contrasting populations of detrital zircons. Below we lay out our case for the latter explanation based on several important considerations. The age of the Marwar basin is certainly younger than the underlying Malani Igneous Province (<750 Ma; Gregory et al., 2008; Figure 14 ). We note the lack of glacially derived sediments within the Marwar as indicating a post Marinoan age (<650 Ma). Fossil evidence points to an Edi acaran age for the Jodphur Group (lowermost Marwar) based on the presence of Arumberia, Beltanelliformis Aspidella and Hiemalora (Kumar and Pandey 2009; Kumar et al. 2009) Pandit et al. (2001) argue that the EdiacaranCambrian boundary should be placed near the upper part of the Bilara Group (Pondlo dolomite; Figure 14 ) on the basis of 13C profiles within the sequence. Srivastava et al. (2012) discovered priapulid like fossils in the Nagaur

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68 sandstone that, along with the earlier finds of Rusophycus Dimophichnus and Cruziana (Kumar and Pandey, 2008, 2010), support the placement of the EdiacaranCambrian boundary (541 Ma) near the base of the Nagaur sandstone. Stratigraphic comparisons between Oman (Huqf Supergroup), Pakistan (Salt Range), Lesser Himalayas (Krol Tal) indicate that deposition in the Marwar can be reliably constrained to between 570521 Ma ( EdiacaranTerreneuvian; Figure 14 ). This age estimate for the Marwar Supergroup is supported by the detrital zircon age distributions in our compilation. The youngest zircon in the population yielded an age of 536 15 Ma consistent with the above cited range ( Figure 41 ; Table 3. 2). In contrast, our age determination for Upper Vindhyan sedimentation is based on the following arguments. The most important age constraint for Upper Vindhyan sedimentation is derived from the 1073 Ma age of the Majhgawan kimberlite (Gregory et al., 2006) and the age of the underlying Rhotas shale in the Lower Vindhyan sequence. Since the kimberlite intrudes the Kaim ur Group, the onset of Vindhyan sedimentation occurred between ~1600 Ma and 1073 Ma. We also note that our compilation of detrital zircon ages confirms the lack of ages <1000 Ma within the Upper Vindhyan sequence. The lack of younger detritus into the U pper Vindhyan is consistent with a Mesoproterozoic age for the basin, but it can also be explained by the presence of physiographic barriers or lack of local younger source material If the Marwar and Vindhyan basins evolved contemporaneously, then we can reject the argument that there was no source region for <1000 Ma zircons because of the proximity of both basins to the graniterhyolite Malani province. Sedimentary strata in both the Marwar Supergroup and Upper Vindhyan sequence were formed at or near

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69 sea level Therefore it is likely that reworking of zircons along a common coastline would supply younger detritus into the Upper Vindhyan sediments ( Cawood et al. 2012) A second possibility is that the Marwar and Vindhyan basins were separated by a significant physical barrier that isolated the two regions. The most logical barrier to deposition in the region is the Great Boundary Fault (GBF). We note that the Bhander Group is deformed along the GBF and therefore it seems unlikely that the GBF for med a significant impediment to input from the west during the time span of Bhander deposition (see figure 12 ). Our Hf data indicates that both the Marwar and Vindhyan Supergoup received input from a region with significant crustal material in the 1.71 .8 Ga range. The Aravalli Belt appears to be the most likely source region and it may be that the Aravalli range acted as both a barrier and a source for sedimentation. The strongest case for a significant age difference between the Marwar and Vindhyan basins is based on paleomagnetic arguments. Gregory et al. (2006) first noted the directional similarity between the 1073 Ma Majhgawan kimberlite virtual geomagnetic pole (VGP) and previously published results from the Bhander Rewa Groups (McElhinney et al., 19 78 ; Klootwijk, 19 73, 1975). Malone et al. (2008) conducted a comprehensive study of the Upper Vindhyan and confirmed the paleomagnetic similarities. More recently, Pradhan et al. (2012) showed that paleomagnetic data from the Great Dyke of Mahoba ( 1090 Ma) is also statistically identical to the Majhgawan kimberlite and Bhander Rewa ( Figure 42 ) The available paleomagnetic data are consistent with a Mesoproterozoic age of deposition for the Bhander Rewa Groups.

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70 Three new paleomagnetic results provide further support for a Mesoproterozoic age. Venkateshwarlu and Chalapathi Rao (in press) studied kimberlite and lamproite intrusions in the Dharwar craton. These intrusions have a variety of U Pb perov skite ages that cluster tightly around 1.1 Ga. The paleomagnetic directions match the aforementioned poles from the Majhgawan kimberlite Great Dyke of Mahoba and Bhander Rewa ( Figure 4 2 ) Meert (personal communication) also notes similar paleomagnetic directions from a limited sampling of the 1.0 Ga Sukhda tuff (Chhattisgarh basin; Figure 42 ). Finally, Davis (2012) showed that paleomagnetic directions from the Marwar Supergroup are significantly different from the Upper Vindhyan directions ( Figure 42 ). In summary, we feel the most parsimonious explanation for the distinct detrital zircon populations in the Upper Vindhyan and Marwar sequences is that the basins evolved independently. The Upper Vindhyan basin closed around 1000 Ma as collisional events in the Eastern Ghats, CITZ and Delhi belts disrupted sedimentation. The Marwar basin formed during the final stages of Gondwana assembly during the EdiacaranCambrian interval (~570521 Ma) The Marwar is one of several Ediacaranage basins within eastern Gondwana that included the Krol Tal (Les ser Himalayas), Salt Range (Pakistan) and the Huqf Supergroup (Oman; Figure 14 ) and perhaps the Molo Group (Madagascar) It should be noted that our conclusion regarding the age of the Upper Vindhyan is consistent with recent age determinations on two other Purana basins, the Indravati Basin (Mukherjee et al. 2012) and the Chhattisgarh Basin (Bickford et al. 2011; Patranabis Deb et al., 2007). Depositional age constraints in the Chhattisgarh basin

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71 suggest closure at ~1000 Ma (age of the Sukhda tuff at the top of the sedimentary sequence; Patranabis Deb et al., 2007). A basal tuff in the Chhattisgarh yielded an age of 1405 Ma (Bickford et al. 2011). Coincidentally, the Indravati Basin contains a tuff unit located at the top of the sedimentary succes sion that yields a weightedmean average 207Pb/206Pb age of 1001 7 Ma (Mukherjee et al. 2012). The corresponding ~1000 Ma closure ages for the Vindhyan, Chhattisgarh, and Indravati basins are thought to be controlled by the collision of East Antarctica and India, producing the Eastern Ghats Mobile Belt (EGMB) of eastern India. This interval of time was likely accompanied by uplift that c ould create barriers to any marine influx into the Purana Basins. Our hypothesis is consistent with the existence of orogenic pulses in the Delhi Belt (to the west of the Vindhyan Basin) and in the Eastern Ghats (to the east ) at around the same time ( Lescuyer et al. 1993; Sivaraman and Raval 1995; BijuSekhar et al. 2003; Kaur et al. 2006; Kaur et al. 2007; Pandit et al. 2003 ) Provenance of Detrital Zircons from the Marwar and Vindhyan Basins Detrital zircon has been proven to be a powerful tool in understanding ancient aeolian processes, paleodrainage patterns, terrane discrimination, and palaeogeographical reconstruc tions (Hieptas et al. 2011 and sources therein). Despite numerous successes many detrital zircon studies fail to identify all source terranes for the sediments under investigation. As an example, studies of detrital zircons derived from Paleozoic clasti c sequences in the Appalachian orogen failed to fully record the defining tectonic events of the orogeny (Gray and Zeitler 1997; McLennan et al. 2001; Eriksson et al. 2004; Thomas et al. 2004; Becker et al. 2005). Provenance determinations for detrital zi rcon populations in the Upper Vindhyan region are hindered by the fact that paleocurrent data from the Vindhyan basin are poorly constrained

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72 ( Akhtar and Srivastava 1976; Kaur et al. in press; Singh 1984). Previous studies on Upper Vindhyan sediments suggested that sedimentation sources are located to the present day south of the Vindhyan Basin. Akhtar (1996) argued that paleocurrent data from the Rewa and Bhander Groups is dominated by a unimodal westerly to northwesterly direction. The Dhandraul Sandst one in the Son Valley sector of the basin indicates west and northwest sloping paleoslopes (Akhtar 1996). Interpretations based on paleocurrent indicators trend s of thickness variation within litho stratigraphic units, and regional stratigraphic relations hips for the marine Rewa basin rocks (Jhiri Shale, Drammondganj Sandstone, Govindarh Sandstone) in the Son Valley sector provide for a northwest southeast oriented paleoshoreline and northeast sloping paleoslope. In contrast, analyses of coastal environme nts for the Bhander Group suggest multi directional sediment dispersal (Akhtar 1973, 1975, 1976, 1978; Akhtar and Srivastava 1976). Detrital input (including zircons) is also reported to be from the southern parts of the Aravalli mountain range and the Bundelkhand massif, suggesting a southerly and westerly trending paleocurrent s (Singh 1984; Malone et al., 2008). Therefore, it must be noted that the expression of tectonic activity that would play a role in the provenance of detritus will be dependent on the paleocurrent(s) that transported sediment into these basins and not all tectonic activity may be recorded in the sedimentary record of the Vindhyan or Marwar basins. Our complete survey of the entire upper Vindhyan succession from the Rajasthan and So n Valley sectors ( Figure 12 ) ; key sandstones from the bottom to top of the Marwar Supergroup ( Figure 14 ) along with the extensive compilation of detrital zircon ages ( Figure 41 ) from this study Malone et al. (2008) and

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73 McKenzie et al. (2011) should, however provide some clarity on potential source regions We have compiled data from this study with that of previous research from Malone et al. (2008) and McKenzie et al. (2011) to provide a comprehensive survey of detrital zircons from the Marwar and V indhyan basins ( Figure 41 ). These studies, while showing variable differences in the abundance of certain detrital zircon age populations, demonstrate very consistent results with that of our own, matching significant populations found in each study. Giv en the caveats noted previously regarding provenance, there are nearby sources that can be identified as potential source regions for our detrital populations. Vindhyan Provenance The results of this study show that upper Vindhyan sediments contain a variety of different age populations, with common age groups seen throughout the complete stratigraphy (Kaimur, Rewa, and Bhander). These common populations occur at ~1 Ga, ~1.1 Ga, ~1.5 Ga, ~1.6 Ga ~1.7 Ga, and ~1.8 Ga (Figure 5 and 9). These ages can be int erpreted in three ways: 1) as a mix of sources that contributed to these formations, with changing paleocurrents contributing to the deposition of a single formation, or 2) that reworking of underlying rocks produced similar age populations in all three ( i ,e the Kaimur was reworked and contributed to the Rewa sediments and the Rewa was reworked to produce similar ages in the Bhander), or 3) a combination of interpretation 1) and 2). This paper prefers interpretation 3) due to the vast array of age populat ions seen in results from Kaimur detrital zircon analyses. Results from McK enzie et al. (2011) and our own show zircons populations with ages of ~1.0 Ga, ~1.1 Ga, ~1.2 Ga, ~1.5 Ga,

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74 ~1.6 Ga, ~1.7 Ga and ~1.8 Ga ( Figure 41 ) It is difficult to attribute t his spread of ages to a single source, so we discuss multiple provenance locations for the detrital zircons found in Upper Vindhyan sediments. Many age populations from our Vindhyan units may be tied to the Central Indian Tectonic Zone (CITZ ; Figure 12 ) located to the south. Roy and Chak araborti (2008) report ages for zircon bearing units in the CITZ. The age ranges in that study fall in broadly defined groups ranging from ~8001000 Ma; 11001200 Ma; 14001600 Ma; and 17001800 Ma. With the exception of the younger (<1000 Ma) ages, most of these pubished ages fall within error of our compiled detrital zircon database from the Upper Vindhyan sediments It is important to note that many of the ages summarized by Roy and Chakraborti (2008) are RbSr isot opic determinations that are not as reliable as determined by the U Pb system in zircon. However, more reliable data have recently become available that might give ins ight to the origin of notable age detrital zircon age populations of ~1.0 Ga, ~1.2 Ga, ~ 1.5 Ga, and ~1.6 Ga, and smaller populations of ages such as ~1.3 and ~1.9 Ga, all attributed to Upper Vindhyan sediments. U Pb zircon and monazite chemical dating of two granite gneiss samples from the southern domain of the Sausar Mobile Belt ( SMB ) broadly constrain magmatic crystallization between 1603 23 Ma and 1584 17 Ma and an overprinting metamorphic event at 1572 7 Ma (Bhowmik et al. 2011) Later, Bhowmik et al. (2012) suggested a collisional event in the northern and central region of the SM B between 1.06 Ga and 0.94 Ga, that is purported to represent the final amalgamation of the North and South Indian blocks. Bhowmik et al. (2012) also suggest that when combined with data from other collisional belts further east of the CITZ, such as the Chhotanagpur Gneissic

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75 Complex and the Shillong Plateau Gneissic Complex, a commonality of Mesoproterozoic to Early Neoproterozoic events is evident. Z ircon s from a metapelite enclave in the Chottanagpur Gneiss Complex (CGC) yield ed mostly concordant 207Pb /206Pb spot ages of 1009 24 Ma 1270 19 Ma 1333 27 Ma 1435 27 Ma 1649 13 Ma 1925 110 Ma and 2569 108 Ma (Rekha et al. 2011) Ages of ~1.3 1.2 Ga were reported by Chatterjee et al. (2010a) and Chatterjee et al. (2010b) from monzanite rim s in schists from the southern portion of the North Singbhum Mobile Belt ( an eastern extremity of the CITZ ; figure 12 ) If these findings prove robust then it must be noted that there is limited understanding of whether the process that created the CITZ, the subduction of the Bastar Craton under the Bundelkhand craton (or vice versa), would have produced enough uplift and exhumation to provide detrital zircon input from a crystalline core source to Mesoproterozoic basins from around the region by ~1 Ga (B ickford et al. 2011). Given this stipulation, it is also possible that ~1.6 Ga zircons were derived from reworking the underlying Deonar Porcellanites and Rampur shale from that ages of 1628 8 Ma; 1602 10 Ma and 1593 12 Ma were reported ( Rasmussen et al 2002; Ray et al. 2006) The Aravalli Mountain region ( Figure 12 ) may be the source for some of the detrital zircon populations in the Upper Vindhyan sequence. The Aravallis experienced magmatic and metamorphic events at ~1.7 1.72 Ga (Kaur et al., 2011). Paleoproterozoic quartzites in the Aravalli region (Khetri Complex) contain an abundance of ~1.8 Ga zircons and there are numerous 1.85 Ga subductionrelated granitoids Therefore either reworking of the quartzites or erosion of the granitoids mig ht be the source of the 1.71.8 Ga zircons in the Upper Vindhyan sequence. This

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76 seems more likely given the close correlation between the from Vindhyan rocks and from around the same region (Kaur et al., 2011; Figure 33 ) It is more problematic to isolate a single source for the 1.01.1 Ga populatio ns that are dominant in the Upper Vindhyan sequence. This interval of time is believed to be a period of supercontinental assembly and zircons of 1.11.0 Ga are found in detrital zircon populations around the globe ( see Hawkesworth et al. 2010; Figure 46 ). There are several potential source regions that are close to the Vindhyan basin. Bose et al. (2011) show that the Eastern Ghat s Mobile Belt records episodes o f tectonothermal activity spanning a large time interval, from the Paleoproterozoic ( monaz ite dated to ~1760 Ma) ; Mesoproterozoic ( zircon and monazites dated to ~1.61.0 Ga) ; Cambrian (550500 Ma granulites locally overprinted by amphibolitefacies metamorphism during this time; Mezger and Cosca 1999) Paleo and Mesoproterozoic zircon populations matching those cited above are present in the upper Vindhyan. Bickford et al. (2011) noted that geochronologic/geothermometric/geobarometric studies of EGMB rocks indicate that collision in the EGMB was ongoing at 1.1 Ga and may be related to the fo rmation of the Rodinia supercontinent Bhowmik et al. (2010) suggested that the pre 1.0 Ga Indian landmass consisted of at least three microcontinental blocks, the North Indian block, the South Indian Block and the Marwar block, that underwent amalgamation at ~1.0 Ga Peak and retrograde stages of metamorphism are recorded in garnet staurolitekyanite schist and garnet biotite muscovite quartz schist from the central domain of the Sausar Mobile Belt as 1062 13 Ma and 993 19 Ma monazite ages (Bhowmik et al. 2012). The

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77 Aravalli/Delhi region is also characterized by granitic intrusions with ages of ~1.0 1.1 Ga ( Pandit et al. (2003); BijuSekhar et al. 2003; Buick et al. 2006; Just et al. 2011) Ages of ~1.1 0.9 have been obtained from rims of some zircons from granitoid plutons occurring in the northern part of the Delhi Fold Belt (BijuSekhar et al. 2003). Other granitic rocks from the Aravalli region have been dated to ~1.00.9 Ga (Lescuyer et al. 1993; Sivaraman and Raval 1995; BijuSekhar et al. 200 3; Kaur et al. 2006; Kaur et al. 2007; Pandit et al. 2003). While we cannot provide a definitive source for the 1.11.0 Ga population of zircon in the Upper Vindhyan sediments, we note the following: 1. 1.1 1.0 Ga zircons form a very small population within the Marwar Supergroup in comparison to the Upper Vindhyan. 2. Point #1 may indicate that the most logical nearby source region for the 1.11. Ga zircons is either the CITZ or the EGMB. 3. The presence of 1.11.0 Ga zircons may indicate a slightly younger age for basinal closure given that uplift and erosion of source rocks within those regions would not be instantaneous. 4. Futur e work might focus on Hf isotopes or other isotopic information from the Vindhyan Supergroup in comparison to potential source rocks in the CITZ and EGMB Marwar Provenance Our Hf isotopic data shows that the ~1.71.8 Ga zircons from Marwar sediments and Figure 33 ). We suggest that the ~1.8 Ga zircons in the Marwar sediments are derived from either reworked quartzites of the Aravalli orogen that contain signifi cant abundances of ~1.8 grains, or from ~1.85 Ga subductionrelated granitoids also found in the Aravalli region.

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78 A local source also provides a reasonable explanation for the 700900 Ma populations in the Marwar sequence. There are abundant sources nearby including the Malani Igneous Province (750800 Ma; Torsvik et al., 2001b, Gregory et al. 2008; Pradhan et al., 2010; van Lente et al., 2009) along with the Erinpura granites and related felsic intrusions (800900 Ma; Crawford 1975; Choudhary et al. 1984; Just et al. 2011). If our arguments are correct about the age of the Marwar sequence, then local sources might also include the ArabianNubian shield and the East African Orogen region ( Figure 44 and 4.5 ) where there are numerous arc related source regions with ages from 700900 Ma ( Mercolli et al. 2006; Bowring et al. 2007 and sources therein). Because we suggest that detritus for the majority of age populations in Marwar sediments correspond to the Aravalli/Delhi region, we can also propose that older zircons (~2.5 Ga) are most likely deriveded from the basement rocks of this area. An ion microprobe zircon study of granitoid and gneissic basement rocks of the Aravalli Mountains yielded crystallization ages of ~2.5 Ga (Wiedenbeck et al. 1996). Pal eogeographic Implications Links between Continental Landmasses from Detrital Zircon R ecords We compare data from our study and similar studies using detrital zircon records to constrain source rock and crustal growth episodes to make connections between the Marwar and U pper Vindhyan sediments and those of proposed cratonic units involved in the assembly of the supercontinents Rodinia, and Gondwana (Figure s 4.2 and 4.3) Rodinia and Gondwana Debate has surrounded the configuration of specific cratons (the Ra yner and Mawson cratonic blocks, Australia, Madagascar, the Seychelles, Sri Lanka and India) involved in the Mesoproterozoic supercontinent of Rodinia, as well as their successive

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79 amalgamation in the supercontinent Gondwana following the Neoproterozoic breakup of Rodinia ( Figure 44 ; Meert and Van der Voo 1996; Rogers et al., 1995; Weil et al. 1998; Powell and Pisarevsky 2003; Meert 2003; Meert and Torsvik 2003; Veevers 2004; Collins and Pisarevsky 2005; Squire et al. 2006; Meert and Lieberman 2008; Malone et al. 2008; Gregory et al. 2009). Apparent polar wander paths and supercontinent reconstructions of specific cratonic masses involved in these reconstructions are hindered by the lack of high quality paleomagnetic data (Meert and Powell 2001; Malone et al. 2008). Previous hypotheses suggested that a united East Gondwana ( Figure 44 ) persisted through the Mesoproterozoic as part of Rodinia through the majority of the Precambrian and until the breakup of Gondwana in the Mesozoic (Powell et al. 1993; Windley et al. 1994; Dalziel 1997; Yoshida and Upreti 2006). This argument has been contradicted by high quality paleomagnetic data (Meert and Van der Voo, 1997; Meert, 2001; Torsvik et al. 2001; Collins and Pisarevsky 2005; Gregory et al. 2009). It is suggested that Rodi nia was created by ~1 Ga, followed by the supercontinent fragmenting into separate crust al plates, caused by extension ( rifting ) during the MidNeoproterozoic (Unrug 1998; Li et al. 2008; Wendorff and Key 2009). This was then followed by MidNeoproterozoic plate collision, with subsequent extension followed by multiple collisions of smaller crustal plates at ~560 Ma and ~520, beginning the formation of the Gondwana supercontinent ( Figure 42 ; Meert 2003; Collins and Pisarevsky 2005; Bingen et al. 2009; Key et al. 2011). Paleomagnetic data from the Indian subcontinent can be useful in evaluating these tectonic models. One of the most recent paleomagnetic poles for this time period, a 771 5 Ma Malani Igneous Suite (MIS ; Torsvik et al., 2001a; Gre gory et al., 2008)

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80 this pole place India at much higher latitudes than coeval poles from Australia (Mundine dikes; Wingate and Giddings 2000), in a similar position to the Takamaka Dikes in the Seychelles dated to 750.2 2.5 by Torsvik et al. (2001b ), th us negating the idea of an amalgamated East Gondwana at 750 Ma. Magmatism of this age (~750 Ma) is also present in Madagascar and the Seychelles (Tucker et al. 201 1 ; Ashwal et al. 2002; Koch h ar 2008; Thomas et al. 2009) and in the ArabianNubian shield (S tern and Dawoud, 1991) In a best case scenario, we can use detrital zircon data to help determine whether events corresponding to the amalgamation and breakup of certain supercontinent cycles may be manifested in upper Vindhyan and Marwar sediments Fur thermore, similarities/differences in detrital zircon spectra c an be used to make a case for and against proximity to India during specific intervals within these supercontinent cycles (see Runcorn, 1962; Hawkesworth et al., 2009; Meert, 2012; Figure 13) Our compilation of detrital zircon ages show input from periods representing the formation of Rodinia, represented by zircon ages of ~1 Ga, ( Vindhyan ) as well as the dispersal of Rodinia and into the amalgamation of Gondwana, seen as zircons with ages bet ween ~800500 Ma (seen only in the Marwar Basin; Figur e s 4.1 and 4.5 ). The Marwar basin retains a detrital record that includes zircon populations that temporally correlate with the assembly and breakup of Rodinia, as well as the assembly of Gondwana. In a reconstruction of Gondwana ( figure s 4.4 and 4.5 ), the Marwar Basin is positioned near other Neoproterozoic basins in Oman (Huqf Supergroup), Pakistan (Salt Range) and the Lesser Himalayas (Krol Tal) and perhaps to the Molo Basin

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81 (Madagascar). Numerous a uthors have noted the similarities among these basins (See Cozzi et al., 2012; Bowring et al., 2007; figure 14 ). Previous studies have attempted to correlate the Marwar to similar aged basins that would have been in close proximity to the region during Gondwana time such as the Salt Range of Pakistan, the Ara Formation (Huqf Supergroup) of Oman, and the Krol Tal succession of the Himalayas, all of which are EdiacaranCambrian in age (Hughes et al. 2005; Jiange et al. 2002, 2003; Kaufan et al. 2006; Maithy and Kumar 2007; Mazumdar and Bhattacharya 2004; Cozzi and Rea 2006; Husseini and Husseini 1990) We suggest that these and other Ediacaran aged sediments, such as the Molo group correlate well with the Marwar Supergroup, when detrital zircon data are com pared. The Marwar, Salt Range, and Ara formation of Oman have already been correlated, due to their nearly identical cycles of carbonateevaporite deposits (Cozzi and Rea 2006). McKenzie et al. (2011) provided an age correlation between the Marwar and the Krol Tal, due to nearly identical detrital zircon population variations, but w hile the Krol Tal successions contain glacial deposits (Tewari and Sial 2007) neither the Salt Range nor the Marwar have evidence of glacial deposits This lack of glacial detr itus is consistent with an age of <635 Ma, marking the end of the Marinoan period (characterized by worldwide glaciations ; Tewari and Sial 2007) and the beginning of the Ediacaran period. While this might negate the age correlation presented by McKenzie e t al. (2011), the extrem ely similar detrital zircon age spectra that the Krol Ta l and Marwar Basins share suggest that the two areas still shared similar provenance,

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82 suggesting at least geographic al proximity T he Krol Tal may represent a slightly older depositional time period. The Ara Formation of the Huqf Group of Oman from the ArabianNubian shield demonstrate 67 nearly identical cycles of carbonateevaporite deposits (Cozzi and Rea 2006; Figure 14 ). This correlation between the Marwar and the Huqf G roup is strengthened by comparison of detrital zircon records. Notably, detrital zircons analyzed from key stratigraphic levels of the Huqf Supergroup (basement, Abu Mahara Group, Nafun Group, and Ara Group of Oman) in a study by Bowring et al. 2007 exhibi t ages that parallel ages in the Marwar Supergroup (~600900 Ga, in excess of 2.5 Ga ) suggest ing proximity of Archean crust during the Neoproterozoic evolution of the eastern Arabian Peninsula. Bowring suggests that these Archean zircons may originate fro m Archean crust in Yemen that ranges in age from about 2.6 to >3.0 Ga. Based on our hypothesis that the Marwar and Oman basins were in close geographical relationship to one another, we suggest that this ~2.5 Ga age might be indicative of basemen t rock fr om the Aravalli region that is observed in Marwar sediments. If this is true, then many of the younger detrital zircon ages seen in the Huqf group may correspond to areas such as the Erinpura Granites and Malani Igneous suite. T he Ediacaran Molo group of Madagascar, deposited between 623 and 553 Ma (Cox et al. 2004), also exhibits similar detrital zircon U Pb spectra to the Marwar Supergroup The Molo group contains zircons ranging in age from ~7001000 Ma as does the Marwar (Cox et al. 2004). Since it is postulated that the Indian and northern Madagascar blocks were in close proximity during Gondwana, we submit that these

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83 (now metamorphosed) sedimentary rocks formed contemporaneously with the basins in adjacent Gondwana regions (figures 44 & 4 5 ).

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84 Fig ure 41 Cumulative U Pb age Probability Density Plots for Marwar and upper Vindhyan Detrital zircons. Red shaded area represents zircons dated to <1000 Ma. Note the absence of ages of <1000 Ma in upper Vindhyan zircons.

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85 Figure 42 Paleomagnetic pole positions at ~1.01.1 Ga from Venkateshwarlu and Chalapathi Rao (in press) kimberlite and lamporite intrusions in the Dharwar craton, Majhgawan kimberlite, Great Dyke of Mahoba, Bhander Rewa, Meert (personal communication) paleomagnetic directions from 1.0 Ga Sukhda tuff (Chhattisgarh). Note that the Marwar Supergroup pole from Davis (2012) with paleomagnetic directions differing from Upper Vindhyan directions.

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86 Figure 43 Geodynamic Map of the supercontinent Rodinia reconstruc tion from Li et al. ( 2008)

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87 Figure 44 Generalized Gondwana reconstruction depicting Neoproterozoic and younger orogenic belts that separate the various cratons of West and East Gondwana (Malone et al. 2008; modified from Gray et al. 2007).

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88 F igure 4 5 Locations of EdiacaranCambrian Basins in the ArabianNubian Shield, Himalayas, Pakistan and Madagascar that correlate with the Marwar Basin as seen in the traditional Gondwana reconstruction.

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89 Figure 46 Detrital zircon spectra representing the phases of orogenesis advocated by Runcorn (1962) from data publi shed in Hawkesworth et al. (2009). Supercontinents represented by these populations include Columbia, Rodinia, and Pangea, and possibly Gondwana

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90 CHAPTER 5 CONCLUSIONS T he Marwar a nd Vindhyan basins are not coeval Th e Marwar basin developed during EdiacaranCambrian time along with several other proximal Gondwana basins (Oman, Madagascar, Pakistan, Lesser Himalayas and perhaps South China). Deposition in the Upper Vindhyan basin is confined to the Mesoproterozoic along with several other Purana basins (Chhattisgarh, Indravati). The Marwar and Vindhyan basins do share a similar source region This conclusion 1.8 Ga are similar, ranging from 13.8 to 0.2 indicative of an ancient crustal source The Hf data are consistent with published Hf isotopic data from the Aravalli region making it the likely source for t he 1.7 1.8 Ga zircons. Other source areas for younger th an ~1.71.8 Ga zircons may be the CITZ, the Bundelkhand Massif, or the EGMB. The CITZ may be responsible for ages of ~1.51.6 Ga or these ages may be derived from the reworking of underlying materials from the Semri Series. The CITZ, Aravalli/Delhi and EGMB are regions are all also characterized by younger aged events at ~1 Ga, most likely corresponding to events stemming from the amalgamation of India with other pieces of Rodinia, or the amalgamati on of the North, South, and Marwar blocks of India. We suggest that detritus from the EGMB is the least likely due to the fact that the CITZ is demonstrated to have been in existence at a time before ~ 1 Ga, preventing transport of sediment from the EGMB to the west into the Vindhyan Basin. While a similar source region is evident, the upper Vindhyans and Marwar basin sediments dev eloped in completely dif ferent time periods The upper Vindhyans should be grouped with other late Mesoproterozoic to early Neoproterozoic sedimentary

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91 sequences such as the Upper Chhattisgarh and Indravati Basins. Marwar Supergroup deposition is now constrained between the Ediacaran and Cambrian time periods, grouping it with basins such as the Salt Range of Pakistan, the Huqf Group of Oman and the Molo Group of Madagascar ( Figure 44 ) The detrital zircon record of the Marwar basin correlates well with detrital zircon databases from these regions as well, suggesting that these basins may have shared source regions with the Marwar. If anything, these terranes exhibited very similar tectonic histories that would have produced related magmatic emplacement, that in turn was recorded in the depositional history, strongly paralleling the Marwar Basin.

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92 LIST OF REFERENCES Akhtar K., and Srivastava, 1976, Ganurgarh Shale of southeastern Rajasthan, India: a Precambrian regressive sequence of lagoontidal flat origin, J. Sediment. Petrol., v. 46, p. 1421. Akhtar, K., 1975, Depositional environments of the Proterozoic Bhander Group, MandalgarhSingoli area, southeastern Rajasthan, Proc. Symp. Sediment, Sedimentation, and Sedimentary Environment, University of Delhi, Delhi, p 9199. Ashwal, L. D., Demaiffe, D., and Torsvik, T. H., 2002, Petrogenesis of Neoproterozoic granitoids and related rocks from the Seychelles: The case for an Andeantype arc origin: Journal of Petrology, v. 43, no. 1. Becker, T., Thomas, W., Samson, S., Gehrels, G., 2005, Detrital zircon evidence of Laurentian crustal dominance in the lower Pennsylvanian dep osits of the Alleghanian clastic wedge in eastern North America, Sedimentary Geology, v. 182, p. 5986. Bhandari, A., Pant, N.C., Bhowmik, S.K., Goswami, S, 2011 1.6 Ga ultrahight emperature granulite metamorphism in the Central Indian Tectonic Zone: insights from metamorphic reaction history, geothermobarometry and monazite chemical ages, G eological Journal v. 46, p. 198 216. DOI: 10.1002/gj.1221. Bhowmik, S. K., Saha, L., Dasgupta, S., and Fukuoka, M., 2009, Metamorphic phase relations in orthopy roxenebearing granitoids: implication for highpressure metamorphism and prograde melting in the continental crust: Journal of Metamorphic Geology, v. 27, no. 4. Bhowmik, S.K., Wilde, S.A., Bhandari, A., 2011 Zircon U Pb/Lu Hf and Monazite chemical dat ing of the Tirodi biotite gneiss: implication for latest Palaeoproterozoic to Early Mesoproterozoic orogenesis in the Central Indian Tectonic Zone, Geological Journal, v. 46, p. 574596. Bhowmik, S. K., Wilde, S. A., Bhandari, A., Pal, T., and Pant, N. C., 2012, Growth of the Greater Indian Landmass and its assembly in Rodinia: Geochronological evidence from the Central Indian Tectonic Zone: Gondwana Research, v. 22, no. 1. Bickford, M. E., Basu, A., Mukherjee, A., Hietpas, J., Schieber, J., Patranabis Deb, S., Ray, R. K., Guhey, R., Bhattacharya, P., and Dhang, P. C., 2011a, New U Pb SHRIMP Zircon Ages of the Dhamda Tuff in the Mesoproterozoic Chhattisgarh Basin, Peninsular India: Stratigraphic Implications and Significance of a 1Ga Thermal Magmatic Ev ent: Journal of Geology, v. 119, no. 5.

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103 BIOGRAPHICAL SKETCH Candler Coyle Turner was born in the city of Cape Canaveral, Florida, to two loving parents William and Ma ry Turner. Soon thereafter, at the tender age of three, he and his family moved to the town of Merritt Island, FL, where he completed ele mentary and middle school at Divine Mercy Catholic School, after which he graduated from Merritt Island High in 2005, w here he was voted Most Talented for his prowess in the art that is guitar playing. Just before graduating high school, Candler was accepted to the University of Florida He gratefully attended the fine institution in the fall of 2005 where he realized his passion for more than just music: Geology Candler would go on to complete his course work in the Geological s ciences tract of the College of Liberal Arts and Sciences, culminating in the reception of his Bachelor of Science in Geology during the fall of 2009. The young and bold graduate then decided to stay on as a m aster s student under the advising of Dr. Joseph G Meert. The two began a hectic but prosperous two and a half years of research on the Vindhyan and Marwar basins, finally culminating in the writing and defendin g of the thesis that you were so fortunate to have the overwhelming pleasure of reading.