STATE OF FLORIDA
STATE BOARD OF CONSERVATION
DIVISION OF GEOLOGY






FLORIDA GEOLOGICAL SURVEY
Robert O. Vernon, Director






GEOLOGICAL BULLETIN NO. 45





THE REGIONAL LITHOSTRATIGRAPHIC ANALYSIS
OF PALEOCENE AND EOCENE ROCKS
OF FLORIDA




By
Chih Shan Chen





TALLAHASSEE
1965










FLORIDA STATE BOARD

OF

CONSERVATION






HAYDON BURNS
Governor


TOM ADAMS
Secretary of State




FRED O. DICKINSON
Comptroller




FLOYD T. CHRISTIAN
Superintendent of Public Instruction


EARL FAIRCLOTH
Attorney General




BROWARD WILLIAMS
Treasurer




DOYLE CONNER
Commissioner of Agriculture


W. RANDOLPH HODGES
Director





Jtorida jjeological Survey

Tallahassee
July 20, 1965

TIonorable Haydon Burns, Chairman
Florida State Board of Conservation
Tallahassee, Florida


Dear Governor Burns:

The Florida Geological Survey will publish, as Bulletin No. 45,
an extensive report covering detailed analyses on the types of rock
and strata deposited during the Paleocene and Eocene periods in
Florida. This report was prepared by Dr. Chih Shan Chen, as part
of his doctoral program at Northwestern University, and it pro-
f des data on the basis of which it is possible to understand the
distribution of these important rocks in Florida.

By studying the environments in which these rocks were formed
and by relating these environments to the regional mountain-build-
ing movements and to the major rock units of Florida, it is hoped
that a greater understanding of the rocks that contain oil can be
had. With this knowledge, new oil fields can be discovered and
developed in Florida.


Respectfully yours,
Robert O. Vernon,
Director and State Geologist























































Completed manuscript received
April 29, 1965
Published for the Florida Geological Survey
By Douglas Printing Company, Inc.
Jacksonville

iv






ABSTRACT


Lithologic and thickness data of the successive Paleocene and
Eocene stratigraphic units in panhandle and peninsular Florida
were obtained by investigating cuttings, cores, and electric logs of
a total of 164 wells selected for this study. These data were em-
ployed for constructing isopach-lithofacies maps, structure maps,
and lithologic cross sections. These maps and cross sections together
with the paleontologic information make possible more reliable in-
terpretations of sedimentary petrogenesis and of the regional tec-
tonics of Paleocene and Eocene time in Florida.
Two distinct sedimentary facies, plastic (panhandle Florida)
and nonclastic (peninsular Florida), have been recognized and
differentiated on a series of isopach-lithofacies maps of the succes-
sive stratigraphic units of the Paleocene and Eocene Series in
the area studied. These two sedimentary facies were separated
by the Suwannee Channel, which acted as a natural barrier, both
sedimentational and faunal, and occupied a narrow belt along
southern Georgia and northern Florida with a northeast-southwest
trend during the time from late Upper Cretaceous to Upper Eocene.
The barrier nature of the Suwannee Channel gradually became less
effective and finally disappeared near the end of Eocene time.
On the basis of lithologic and paleontologic data together with
the ecologic and environmental conditions inferred in this study,
the following interpretations concerned with the regional sedimen-
tation were made. In peninsular Florida, nonclastic sediments,
carbonates and evaporites, were formed on a stable carbonate bank
or shelf in warm, shallow-water, and open marine environment
which could be comparable to those existing today in the Great
Bahamas, Florida Bay and Keys, and Campeche Banks. In pan-
handle Florida, plastic sediments were laid down on a relatively
unstable shelf in transitional or deltaic and shallow water marine
environments. Isopach-lithofacies maps indicate that plastic sedi-
ments become coarser and more dominant northward toward the
Appalachian Piedmont, while carbonates and finer clastics are the
major lithologies southeastward near the Suwannee Channel and
southward toward the Gulf. The principal source area of those
terrigenous materials is considered to be the Southern Appalachians.
Stratigraphic analysis indicates that only epeirogenic move-
ments affected the area during Early Tertiary time. Several minor
disconformities have been recognized at the outcrop area, but they
are generally not recognizable in the subsurface in panhandle and






peninsular Florida, except at the contacts of the Ocala Group which
show unconformable relationships with beds lying above and below.
The fact of gradual but steady spreading of the nonclastic facies
northerly and northwesterly over the plastic facies during Early
Tertiary time may be the result of continued marine transgres-
sion. Some sporadic regressions occurred during Paleocene and
Eocene time as manifested by the presence of local and regional
unconformities.
Paleogeographic maps of the successive Paleocene and Eocene
stratigraphic units studied are reconstructed on the basis of the
series of isopach-lithofacies maps, lithologic and paleontologic data,
and ecologic and environmental conditions inferred in this study.







ACKNOWLEDGMENTS


The writer is indebted to L. L. Sloss of Northwestern Univer-
sity for directing this study through its various stages to comple-
tion. Thanks are due to W. C. Krumbein for advice and suggestions
on analyses of lithologic data; further thanks are due to other
members of the faculty in the Department of Geology, Northwest-
ern University for their interest, suggestions, and criticism, and
to H. G. Goodell of the Florida State University for suggesting the
problem and for assistance when the writer was a graduate student
at that university.
Grateful acknowledgment is rendered to the Florida Geological
Survey for permitting the writer unrestricted use of well samples,
cores, and mechanical logs at its well sample library and providing
a part of the expense of the study; and to R. O. Vernon, director of
the Florida Geological Survey, for helpful suggestions and kind
assistance; to the Society of Sigma Xi and RESA Research Fund
for awarding a research grant during the summer of 1962; to Sun
Oil Company in Tallahassee, Florida, particularly D. J. Munroe, for
allowing the writer use of electric logs; to John Pressley, technician
at the Department of Geology, Northwestern University for grind-
ing thin sections; and to the Graduate School of Northwestern Uni-
versity for providing research funds.










CONTENTS
Page
A b stra c t .... .................................................................................................................................................... .................... v
Acknowledgments ........................ .......................... ... ............ vii
Introdu action ...... . ..................................................... ...... ................................. ............... ............................. 1
G eolog ic setting g ..................................................... .......... ............................................ ......................................... 7
A analytical procedures ...................................................................................................................... ..... 27
Descriptive stratigraphy ........................................................................... ....... .. ...... 31
General statement ................................................................. ......................... ...... 31
Cedar Keys and Midway Formations ..... .................................................................................... 41
Pre-Midwayan Unconformity ................................................ ............. ...... .. 41
C edar K ey s F orm a tion ..................................................................................... .............. .............. 42
Midway Formation ...................................................... ...... 44
Oldsmar Limestone and Wilcox Formation ........................................ ............................ 47
Oldsmar Limestone ................................._.................... ...... 47
W ilcox F orm ation ..................................................................................... ........................... ............... 53
Lake City and Avon Park Limestones and undifferentiated
C laiborne G rou p ........................ ....... ....................................... ..................... .. ... ..................... ........... 55
G general state ent ............... ........................................ ............... ............... ......................... 55
Lake City Limestone ................ ....................... ........................... 56
Avon Park Limestone ................................................................ ....................................................... 59
Undifferentiated Claiborne Group .......................................................................................... 60
O cala G group ..................................... ................ ................ 66
Pre-Jacksonian (sub-Ocala) Unconformity ........................................ 66
Jackson S tag e .................................................................................... . ... .............. .... .. ... 66
Summary of Eocene Series ............................................. ............................ .................... .... 70
Interpretative stratigraphy ............. ............................... ..... ....7..................... ................................ 74
G general consideration ............................................. ................................ .................. ... ........... 74
Regional tectonics and depositional environments ......................... ........................ 75
L ithologic characteristics ..................................................... .............. .................. ................. 75
Paleontological characteristics ................................ ............. .......... ... ............ .......... 78
Tectono-environmental conditions and sedimentation ....................... ................. 81
Nonclastic facies (peninsular Florida region) ..................................................... 81
The Suwannee Channel ..................................... ............................................... ..... 82
Clastic facies (panhandle Florida and its adjacent areas)................................ 84
Paleogeography ................................... ....... .................................. .......................................... 85
B bibliography ...................................... .... . .......................... ................................................. 92
A p p en d ix .......................................... .................................................................................. ... .................................... .. 9 8

ix







ILLUSTRATIONS

Figure Page
1. Regional geological map of southeastern United States (compiled
from Geological map of North America, 1960, and Surface
occurrences of geological formations in Florida, 1959)..... .............................. 2

2. Major structural features of southeastern coastal plain and the
Bahamas (modified after the tectonic map of the United States,
1962, and Pressler, E. D ., 1947) ........................................-............ ..... ......... ......... 3

3. W ell location m ap.......................................................................... ..................................... 4

4. Map showing the shifting of clastic-nonclastic facies boundary
through the geologic time from Upper Cretaceous to Upper
E ocene ........ ................... .. .... ............. .......................... ............. ............................ 9

5. A. Structure map, contoured on top of Paleocene Series,
showing the location of Suwannee Channel (synclinal axis).
B. Isopach map of Paleocene Series showing thin accumulation
within the Suwannee Channel (synclinal axis)......................................... 11

6. A. Structure map, contoured on top of Lower Eocene rocks
showing the location of Suwannee Channel (synclinal axis).
B. Isopach map of Lower Eocene rocks showing thin accumulation
within the Suwannee Channel (synclinal axis)............... .............................. 12

7. Structure map of Florida showing contours on top of "Taylor
kick" (Upper Cretaceous)...................................... ............... ............................ ... 14

8. Structure map of Florida showing contours on top of Upper
C retaceous ....................... ........ ...................... ................. ........................................ 15

9. Structure map of Florida showing contours on top of Paleocene
S series .......................................................................... .......... ... .......... ...... ................... 16

10. Structure map of Florida showing contours on top of Sabine
Stage (Lower Eocene).... ....................... .................................. ....... .. .. 17

11. Structure map of Florida showing contours on top of Claiborne
G group (M middle E ocene) ............................................................... .......... .... .................. .. 18

12. Structure map of Florida showing contours on top of Ocala
Group (Upper Eocene) ............................ .. ........ ......................................... 19

13. Isopach map of Claiborne Group (Middle Eocene).........................- ...... 21






Figure Page
14. Isopach map of Ocala Group (Upper Eocene)........................................................ 22

15. Isopach-lithofacies map of Paleocene-Eocene Series of Florida............. 24

16. Isopach-lithofacies map of Paleocene-Eocene Series of panhandle
F lorida ................ ......... .................................. ............ .... ................. ...... .... ................. 25

17. Isopach-lithofacies map of Paleocene-Eocene Series of panhandle
F lo rid a ............................. .................................................... .... ................................ ...................... 2 6

18. Index map showing location of cross sections.......................................................... 32

19. Stratigraphic cross section (A-A') of Paleocene-Eocene strata
o f F lo rid a ..................................................................................................... ......... .............. ................. 3 3

20. Stratigraphic cross section (B-B') of Paleocene-Eocene strata
of F lorida ..................................... ................................. .......... ............. ..... 34

21. Stratigraphic cross section (C-C') of Paleocene-Eocene strata
of F lorida .................................................................................... ..................................................... 3 5

22. Stratigraphic cross section (D-D') of Paleocene-Eocene strata
of F lorida .......................... ............................ ................ .......... .............................................. 36

23. Correlations of Paleocene-Eocene strata ................................................................. 37

24. Isopach-lithofacies map of the Paleocene Series of Florida.............. ... 38

25. Isopach-lithofacies map of the Cedar Keys Formation
(Paleocene Series) of peninsular Florida............... ..................... ...... .................... 39

26. Isopach-lithofacies map of the Midway Formation (Paleocene
Series) of panhandle Florida................................................................................. ....... 40

27. Evaporite percentage map of the Paleocene Series of Florida............... 45

28. Isopach-lithofacies map of the Sabine (or Wilcox) Stage of Florida... 49

29. Isopach-lithofacies map of the Oldsmar Limestone (Sabine or
Wilcox Stage) of peninsular Florida ........................................................... ............. 50

30. Isopach-lithofacies map of the Wilcox Formation (Sabine or
Wilcox Stage) of panhandle Florida.............................................................................. 51

31. Evaporite percentage map of the Sabine (or Wilcox) Stage
of Florida .......... ................................. ........................................................................................... .... 52







Figure Page

32. Regional distribution of highly carbonaceous dolomite and limestone
interbedded with thin streaks or thin beds of peat in Northern and
central Florida near the end of early Middle Eocene Time
(sh added a rea ) .............................................................................................. ................................ 58

33. Isopach-lithofacies map of the Claiborne Group (Claiborne
S tage) of F lorida....................... .................. ..... .................................. ................................... 61

34. Isopach-lithofacies map of the Claiborne Group (Claiborne
Stage) of peninsular Florida.......................................................................................... 62

35. Isopach-lithofacies map of the Claiborne Group (Claiborne
Stage) of panhandle Florida ........................................................................................... 63

36. Evaporite percentage map of the Claiborne Stage of Florida........... 64

37. Isopach-lithofacies map of the Ocala Group (Jackson Stage)
of F lorida ................................................. ......... .................................... ....... ........... ........... 68

38. Isopach-lithofacies map of the Eocene Series of Florida....................... ..... 71

39. Isopach-lithofacies map of the Eocene Series of peninsular Florida.. 72

40. Isopach-lithofacies map of the Eocene Series of panhandle Florida... 73

41. Paleogeographic map during Paleocene (Midwayan) deposition............... 88

42. Paleogeographic map during Lower Eocene (Sabinian) deposition..... 89

43. Paleogeographic map during Middle Eocene (Claibornian)
deposition .... .................................... ..................................... .......................... ...............-..... 90

44. Paleogeographic map during Upper Eocene (Jacksonian)
dep position ............ .............................. ......... ....................... ... .............................. ................ 9..... 91


Table
1. Location of wells .......................................................... ........ .................. 98








THE REGIONAL LITHOSTRATIGRAPHIC ANALYSIS
OF PALEOCENE AND EOCENE
ROCKS OF FLORIDA
By
Chih Shan Chen
INTRODUCTION
The sedimentary rocks of Florida range in age from Cambro-
Ordovician to Recent (Applin, 1951a, 1951b), although rocks of
Cretaceous and Tertiary age are dominant, volumetrically and
really. Cenozoic sediments in Florida range in age from Paleocene
to Recent, but only post-Eocene rocks are exposed over most of the
state (fig. 1). Crystalline rocks of possible Precambrian age have
been encountered in several deep test wells in central Florida (Ap-
plin, 1951a, 1951b), but the oldest rocks exposed at the surface are
late Middle Eocene in age and occur in Citrus and Levy counties in
the northwestern part of the peninsula, on the crest of the Ocala
Uplift (figs. 1 and 2). Upper Eocene rocks crop out around these
Middle Eocene strata and outline the periphery of this uplift, other
Upper Eocene exposures are in the area of the Chattahoochee Arch
near the common boundary of Alabama, Florida, and Georgia (figs.
1 and 2).
This paper is in the nature of a reconnaissance study or a prog-
ress report on investigations of the complex stratigraphy of the
Paleocene and Eocene strata in peninsular and panhandle Florida.
Interpretations as here presented are tentative and subject to
modification as new data emerge from further drilling and geophys-
ical surveys.
In the preparation of this study, lithological and other geologi-
cal data were obtained by examining well cuttings, cores, and
mechanical logs from a total of 164 selected wells (fig. 3), most of
them penetrating Mesozoic or older rocks. The information obtained
was used for the following purposes: (1) to construct regional
lithofacies, isopach, and structure maps, (2) to determine the verti-
cal and lateral relationships among the major lithologic units, and
(3) to interpret the depositional environments in the light of re-
gional tectonics.
Two distinct sedimentary facies have long been recognized by
many geologists who have worked in the area: the land derived-
clastic facies of the Florida panhandle and the facies of the allo-
chemical rocks of the Florida Peninsula. Such Paleocene-Eocene
rocks of the peninsula are composed almost entirely of carbonates








2 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


800


.ALA.
FLA.


FLA-----


LEGEND


LII
I -_



F -3-


POST-EOCENE
UPPER EOCENE
MIDDLE EOCENE
LOWER EOCENE
PALEOCENE
UPPER CRETACEOUS
PALEOZOIC
PIEDMONT CRYSTALLINE


5o O 100 MILES

0 50 100 KILOMETERS


.9


85'


800


Figure 1. Regional geological map of southeastern United States (compiled
from Geological Map of North America, 1960, and Surface Occurrences of
Geological Formations in Florida, 1959).






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


Figure 2. Major structural features of southeastern Coastal Plain and the
Bahamas (modified after the Tectonic Map of the United States, 1962, and
Pressler, E. D., 1947).







4 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


N




Ii


LEGEND

) INCOMPLETE SAMPLES

C COMPLETE SAMPLES

ELECTRIC LOG ONLY

ELECTRIC LOG 8
INCOMPLETE SAMPLES

ELECTRIC LOG 8
COMPLETE SAMPLES

1021 FLORIDA GEOLOGICAL SURVEY
WELL NUMBER

X-7 OFFICIAL WELL NUMBER
UNKNOWN


SCALE
0 25 50 75 100 MILES
0 50 100 KILOMETERS


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 3. Well location map.


X-7






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


and evaporites. Dolomite, anhydrite, and gypsum are the principal
lithologic components of the Paleocene rocks; dolomite and fossili-
ferous limestone are predominant in the Eocene rocks. In panhandle
Florida the plastic facies comprises sandstone, shale, and limestone
for the entire Paleocene-Eocene succession. The facies boundary
between silicate fragment plastic and the nonclastic faces is rather
sharply defined throughout all the stratigraphic units studied, how-
ever, it is reasonable to suggest that the relations between these
two sedimentary facies are in interfingering rather than knife-edge
contact.
A complete review of previous studies in the area up to 1944 is
well summarized by Applin and Applin (1944). Some of the most
significant contributions to the knowledge of the regional subsur-
face geology of the area completed since 1944 are briefly reviewed
here.
Applin and Applin (1944, 1947) have studied the regional sub-
surface stratigraphy, paleontology, and structure of Florida and
southern Georgia and have presented much information as cross-
sections, maps, and paleontological studies. New local formation
names assigned to rocks of the nonclastic facies in peninsular
Florida have been introduced, and relationships between the plastic
facies of the Florida panhandle and the nonclastic facies of the
peninsula have been discussed and correlations suggested.
Cole (1944, 1945) has made valuable contributions to our knowl-
edge of the subsurface stratigraphy and micropaleontology of the
area. He named the Cedar Keys Formation a stratigraphic unit of
Lower Eocene age (now considered by the Coastal Plain geologists
as Paleocene) in peninsular Florida (Cole, 1944).
Applin and Jordan (1945) made an extensive study of fora-
minifers from which they described and listed fossils charac-
teristic of formations ranging in age from Upper Cretaceous to
Oligocene.
Recently, Cheetham (1963) studied the abundance and distri-
bution of marine fossils, particularly cheilostome bryozoans, in the
Upper Eocene sediments in the eastern Gulf Coast region (including
panhandle Florida and central peninsular Florida). He interprets a
shoal-water tropical environment of water depth probably less than
150 feet to have existed over most of the Florida Platform during
the Upper Eocene.
Applin (1951b), in his investigation of pre-Mesozoic rocks in
Florida and adjacent states, recognized a deeply buried structure,







6 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

the Peninsular Arch, in rocks older than the Mesozoic; he also
grouped these rocks into three major categories: (1) plutonic and
metamorphic rocks of possible Precambrian and/or Paleozoic age,
(2) possible Precambrian or Early Paleozoic rhyolitic lavas and
pyroclastic rocks, and (3) Paleozoic sedimentary rocks. His conclu-
sions contribute important and fundamental knowledge not only of
the early geologic history of Florida, but also of the regional tec-
tonics of the southeastern United States.
Pressler (1947), on the basis of subsurface stratigraphy, desig-
nated the area covering the region of South Florida, the Bahamas,
Cuba and the intervening areas as the South Florida Embayment;
Carsey (1950) named the same feature the South Florida Basin.
Vernon (1951) suggested that the Ocala Uplift probably was initi-
ated during Early Miocene time, resulting in a gentle flexure in
Tertiary sediments on the west flank of the Peninsular Arch.
Applin (1952) and Toulmin (1952) estimated the total volume
of the Mesozoic and Cenozoic sediments in Florida and Georgia
respectively, on the basis of the data obtained primarily from the
oil test wells and secondarily from the outcrop measurements. Toul-
min (1955) made a regional stratigraphic study of the Cenozoic
sediments of the southeastern Coastal Plain. He also suggested
that the two distinct sedimentary facies, the plastic faces of pan-
handle Florida and southern Georgia and the nonclastic facies in
peninsular Florida, are separated structurally by the Peninsular
Arch. Puri (1957), on the basis of a study of the stratigraphy and
biostratigraphy of Upper Eocene rocks in Florida, used the term
"Ocala" as a group name and assigned three formations to it, from
oldest to youngest, Inglis Formation, Williston Formation, and
Crystal River Formation.
Recently Goodell and Yon (1960) demonstrated the lateral com-
plexities of post-Eocene sediments in Florida by lithofacies maps
and cross sections; these authors treated the lithologic data quanti-
tatively, and discussed the facies patterns and the parameters of
sedimentation in the light of regional tectonics. Most recently
Toulmin and LaMoreaux (1963) have made a detailed study of the
section of Upper Cretaceous and Tertiary strata exposed along the
Chattahoochee River in the southeastern Coastal Plain and they
consider the section to be a significant connecting link between the
Atlantic and Gulf Coastal Plains.
A considerable amount of geophysical information reflecting
the structural trends of magnetically heterogeneous Paleozoic and
Precambrian rocks beneath rocks of Mesozoic and Cenozoic age in






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


the southeastern Coastal Plain of the United States has appeared
in print (Drake and others, 1963; E. R. King, 1959; Lee and others,
1945; Lyons, 1950 and 1957; and Miller and Ewing, 1956). Lee and
others (1945) have made a magnetic survey of the Florida Penin-
sula. Drake and others (1963), King (1959), and Lyons (1950), on
the basis of studies of geophysical data represented by the regional
magnetic and gravity maps in the area of Florida and the Bahamas,
state that two distinguishable regional magnetic trends or provinces
exist: a northern province of predominant northeast trends, and a
southern province of northwest trends cutting with discordance
across the northeast trends.
GEOLOGIC SETTING
The term "Florida Platform", as here used, covers peninsular
Florida, the broad continental shelves off the west and east coasts
of the Florida Peninsula extending seaward to the -500-foot con-
tour, and the Great Bahama Bank (fig. 2). Owens (1960) proposed
the term "Florida-Bahama Platform" encompassing the Bahama
Islands and most of the Florida Peninsula and shelf. The platform
is bounded on the south by the overthrust sheet or high angle
tilted fault blocks of the Great Antilles (Owens, 1960; Pressler,
1947), on the west by the West Florida Scarps, and on the east by
the North Atlantic Ocean Deep. This platform has been considered
by many geologists (King, 1950, 1961, 1964; Murray, 1961, 1963)
as a significant seaward extension of the Appalachian and/or
Ouachita structural belts, although definite relations are still
undetermined.
Recently, Drake and others (1963) and E. R. King (1959), on
the basis of the regional pattern of the magnetic anomaly map of
Florida and the Bahamas together with the gravity and seismic
results, suggest that two rather distinctive regional magnetic
trends or provinces exist in the area: northeast-trending anomalies
in northern Florida which parallel and presumably reflect buried
segments of the Appalachian system, and northwest-trending
anomalies in southern Florida and the Bahamas apparently trun-
cating the northeast trends. Such northwest structural trends
may reflect an extension of the Ouachita system and may indicate
that the Ouachita system is younger. However, Woollard (1958),
on the basis of the distribution of earthquake epicenters, suggested
that these two systems are independent, but contemporaneous,
intersecting with a "T" relationship somewhere beneath the
Mississippi-Alabama Coastal Plain.






8 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

Several measurements of total magnetic intensity have been
made by Miller and Ewing (1956) in the region west of peninsular
Florida, from the continental shelf, across the West Florida Escarp-
ment to the deep basin of the Gulf of Mexico. The geophysical data
indicate that the magnetic field over the west Florida Platform has
numerous strong anomalies which are apparently not linear. Al-
though a further survey of the area is needed to make a more
reliable interpretation, it seems to the writer that the result re-
ported by Miller and Ewing gives no direct support to the statement
made by King (1959) and Drake and others (1963) that a strong
southeasterly trend passing through southern Florida into the
Bahamas is probably an extension of the Ouachita system.
Lyons (1950) has published a gravity map of the United States.
His regional gravity map of Florida is very similar to that of King's
(1959) magnetic map of the same area both in overall trends and
in individual features. However, the well-marked positive and nega-
tive trends of the Appalachian and Ouachita structural belts dis-
appear in the Atlantic and Gulf Coastal Plains and Mississippi
Embayment as shown on the gravity map of southeastern United
States. The linear trends of gravity anomalies may indicate the
extension of Appalachian system in southwestern Alabama and
southern and central Mississippi. It is rather surprising that the
geophysical evidence is quite contradictory to the result revealed
by the subsurface drill data which indicate that both structural
belts extend unchanged for a long distance beneath the coastal plain
cover.
Evidence and inferences, both geologic and geophysical, so far
as we know currently are insufficient to solve the problem of the
relations between the Ouachita and Appalachian systems. It seems
to the writer that the knowledge of the relationship between these
two major structural belts and of the regional distribution of the
basement rocks beneath the southeastern Coastal Plain of the
United States could be further clarified by detailed investigation in
the critical regions of the continental shelf off the west coast of
Florida and the Mississippi Embayment.
Two distinct sedimentary facies, plastic and non-clastic, have
been recognized in stratigraphic units ranging in age from Lower
Cretaceous to Upper Eocene in the area (Applin, 1951a). However,
the position of the facies boundary has shifted northward and
northwestward through geologic time as indicated by studies of
the regional subsurface geology of the area (fig. 4).
Applin and Applin (1944), in their study of subsurface strati-






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS 9

















S UPPER EOCENE TIME

MIDDLE EOCENE TIME
. LOWER EOCENE TIME
'-* PALEOCENE TIME

--- UPPER CRETACEOUS TIME

FACIES BOUNDARY U
SHIFTING DIRECTION





0 50 100 MI.
9 5o IqO KM. "* --"** -



Figure 4. Map showing the shifting of clastic-nonclastic facies boundary
through the geologic time from Upper Cretaceous to Upper Eocene.





10 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

graphy ranging in age from Upper Cretaceous to Early Tertiary
in Florida and southern Georgia, have suggested that there was
"a channel or trough extending southwestward across Georgia
through the Tallahassee area of Florida to the Gulf of Mexico."
This channel cut nearly at right angles to the trend of the Penin-
sular Arch and lay between the carbonate-evaporite facies to the
southeast and the terrigenous plastic facies to the north and
northwest.
The term "Suwannee Strait" was first coined by Jordan (1954)
to designate the same feature and this usage was further amplified
by Hull (1962). The paleogeographic feature was a slightly deeper
passage across a shallow shelf as discussed in a later chapter.
Therefore, the term "channel" is more descriptive than "strait" and
is adopted in this report for the prominent belt of rapid facies
changes that is apparent throughout the time span of the strata
here considered.
The continuous existence of the Suwannee Channel, at least
through Early Tertiary time, has been recognized by the writer
and illustrated in figures 5 and 6 (also see p. 42). The relatively thin
deposition within the channel during Paleocene and Lower Eocene
time is suggestive of continued elevated current action through the
channel during that time. The currents could have considerably re-
duced the rate of accumulation of fine sediments within the channel
and would have prevented the spread of fine terrigenous sediments
over the peninsula area to the southeast.
The Peninsular Arch, forming the backbone of the Florida Plat-
form, is one of the major regional subsurface structures in the
area (fig. 2). The arch trends south-southeast and extends from
southeastern Georgia through Florida into the Great Bahamas.
Applin (1951b) interprets the presence of pre-Mesozoic rocks form-
ing the core of the Florida Peninsula, to indicate an area of
nondeposition during post-Silurian Paleozoic time, and that the
subsequent regional movements during the post-Paleozoic time were
responsible for shaping the present configuration of the Peninsular
Arch and the South Florida Basin. It has been suggested by Mur-
ray (1963) that the arch is a mobile "swell or welt" in the develop-
ing Gulf-Atlantic Coastal geosynclinal province.
An oil test well has been drilled to more than 14,500 feet on
Andros Island of the Bahamas. Lithologic data indicate that the
whole section penetrated is composed entirely of relatively pure
carbonates (limestone and dolomite) of Upper Mesozoic age. Re-
cently, a second test, the California-Gulf, Cay Sal 4 No. 1, was






11


REGIONAL LITHOSTRATIGRAPHIC ANALYSIS

A


Figure 5. A. Structure map, contoured on top of Paleocene Series, showing
the location of Suwannee Channel (synclinal axis). B. Isopach map of Paleo-
cene Series showing thin accumulation within the Suwannee Channel (synclinal
axis.)





















































Figure 6. A. Structure map, contoured on top of Lower Eocene rocks, showing
the location of Suwannee Channel (synclinal axis). B. Isopach map of Lower
Eocene rocks showing thin accumulation within the Suwannee Channel (syncli-
nal axis).





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


drilled by Bahama California Oil Company and Bahama Gulf Oil
Company on Cay Sal Bank in the southwestern Bahamas, which is
approximately 131 miles due south of Miami, Florida (Wassall and
Dalton, 1959). The well was abandoned at 18,906 feet early in 1959
because it had failed to locate the section of porous, dolomitized,
limestones intercalated in anhydrite beds, which is the producing
section in Sunniland field in South Florida. Neither lithologic nor
stratigraphic data pertaining to this test have been released. How-
ever, such fragmental subsurface data as have been provided prove
to be valuable information for this little known region. Geologists
have suggested that the Bahama Banks, although at present sepa-
rated from peninsular Florida by the Florida Strait with moderate
depth (about 2500 feet), are an extension of peninsular Florida,
and that the present-day existing conditions of sedimentation may
have prevailed for a long time (Eardley, 1951, 1962; Newell, 1955).
The term "Ocala Uplift" as here used is intended to mean the
local and younger (Late Tertiary) structural feature as distinct
from the "Peninsular Arch" previously described. It should not be
used as a synonym for the Peninsular Arch as is current in much
of the literature. Vernon (1951) stated that the Ocala Uplift was
developed during post-Oligocene and Lower Miocene time in the
Tertiary sediments as a gentle and rather local flexure in central
peninsular Florida. The uplift centers around the outcrops of the
Ocala Group (Upper Eocene) and Avon Park Limestone (late Mid-
dle Eocene) in Citrus, Dixie, and Levy counties on the west coast
of the Peninsula, and its axis lies parallel to, but not coincident
with, the axis of the Peninsular Arch (figs. 1 and 2). Both surface
and subsurface geological information also indicates that there are
no close structural relations between these two features (Applin,
1951b).
A series of structure maps representing lithologically correl-
ative surfaces in successive stratigraphic units is presented as
figures 7-12. These maps show the structural relationships through
time between the Peninsular Arch and the Ocala Uplift. It is quite
apparent that the Peninsular Arch is the major structural element,
the core of the Florida Peninsula and possibly of the Bahamas,
since at least late Upper Cretaceous time and even much older.
Applin (1951b) concludes that this structure dates back to the
Paleozoic.
Figure 7 is a structure map contoured on the top of the so-
called "Taylor kick" (Upper Cretaceous). This is a very distinctive
and prominent electric log characteristic in which both resistivity







14 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


/


CONTOURS ON TOP OF
"TAYLOR KICK"
(UPPER CRETACEOUS)


DATUM: SEA LEVEL
CONTOUR INTERVAL: 500 FEET


0 WELL CONTROL POINT


0 25 50 75 100 MILES
0 50 100 KILOMETERS


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY

Figure 7. Structure map of Florida showing contours on top of "Taylor kick"
(Upper Cretaceous).







REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


/V


CONTOURS ON TOP OF
UPPER CRETACEOUS


DATUM: SEA LEVEL
CONTOUR INTERVAL: 500 FEET


0 WELL CONTROL POINT


0 25 50 75 100 MILES
0_ 50 100 KILOMETERS
0 50 100 KILOMETERS
I I I


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY

Figure 8. Structure map of Florida showing contours on top of Upper
Cretaceous.


15


0 c-






16 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


Figure 9. Structure map of Florida showing contours on top of Paleocene
Series.







REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


CONTOURS ON TOP OF

SABINE STAGE ,

(LOWER EOCENE)
-\ \ o

DATUM: SEA LEVEL /
CONTOUR .INTERVAL: 200 FEET *



WELL CONTROL POINT



200"
000

2500

0 25 50 75 100 MILES

0 50 100 KILOMETERS C


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY

Figure 10. Structure map of Florida showing contours on top of Sabine Stage
(Lower Eocene).







18 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE
I x --NX % 1% 1


0o
o o
'1 '


/


S,0


CONTOURS ON TOP OF
CLAIBORNE GROUP
(MIDDLE EOCENE)


DATUM: SEA LEVEL
CONTOUR INTERVAL: 200 FEET


0 WELL CONTROL POINT


0 25 5p 75 100 MILES
0 50 100 KILOMETERS
-==Now


,"0o


. \00
% 200


o0


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY

Figure 11. Structure map of Florida showing contours on top of Claiborne
Group (Middle Eocene).






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


1


CONTOURS ON TOP OF
OCALA GROUP
(UPPER EOCENE)


DATUM: SEA LEVEL
CONTOUR INTERVAL: 200 FEET


* WELL CONTROL POINT
-1r" OCALA GROUP ABSENT


0 25 5p 75 100 MILES
O 50 100 KLOMETERS
I C L. i


L CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY
Figure 12. Structure map of Florida showing contours on top of Ocala Group
(Upper Eocene).


19


i
1






20 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

and self potential curves are very low. This strong depression as
shown on the potential curve can be easily recognized since the,
potential curve throughout most of the Upper Cretaceous section
of peninsular Florida exhibits a rather flat and almost straight line.
The inflection of the electrical responses is believed to represent a
thin shale bed and, except for the southern end, is present in almost
all of the wells which penetrate the basal Taylor beds in peninsular
Florida. In panhandle Florida this electric-log departure is rather
obscure, so that the contours shown on the map (fig. 7) are highly
interpretive in this area.
As has been pointed out, the Peninsular Arch has been the
dominant structural feature in peninsular Florida since at least
Paleozoic time, and persisted through the Eocene and perhaps even
later. The Ocala Uplift, on the other hand, is comparatively a much
younger structure, first beginning to develop in post-Oligocene or
probably Lower Miocene time. Two isopach maps (figs. 13 and 14)
of the Claiborne Group (Middle Eocene) and Ocala Group (Upper
Eocene) indicate that there is no thinning of these strata along the
crest of the Ocala Uplift, although these isopach maps may not
represent the actual pattern because of the effect of post-Claiborne
and post-Ocala erosion. The position of the thin areas shown on
these maps (figs. 11-14) strongly suggest that it is unlikely that
the original geometry of the units has been radically changed by
post-depositional erosion. In addition the attitude of Miocene beds
which directly overlie the Ocala Group along the crest of the uplift
suggests that the Ocala Uplift was formed during post-Oligocene
or Lower Miocene time.
The Chattahoochee Arch, a minor structural feature along the
Appalachicola and Chattahoochee rivers, is a feature in which
Paleozoic sediments are encountered below red beds of probable
Jurassic age. The crest of the arch trends northeast near the com-
mon boundary of Alabama, Florida, and Georgia (fig. 2).
The term "South Florida Embayment" of the Gulf of Mexico
Basin was originally proposed by Pressler (1947) to include the
area of southern Florida south of the Ocala Uplift (the Peninsular
Arch in the writer's usage), the Bahamas, Cuba, and the interven-
ing submerged areas. The cynclinal axis of the embayment plunges
toward the Gulf and trends northwestward between Cuba and the
Bahamas, across the Bahama Banks to the Florida Keys, and across
Dade and Monroe counties to the southwest coast of Florida. Carsey
(1950) used "South Florida Basin" to designate this regionally
downwarped area. He placed its synclinal axis east-west through







REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


* WELL CONTROL POINT


CONTOUR INTERVAL


200 FEET


0 25 50 75 100 MILES

0 50 100 KILOMETERS


SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 13. Isopach map of Claiborne Group (Middle Eocene).


21








22 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


* WELL CONTROL POINT

fI77 OCALA GROUP ABSENT



CONTOUR INTERVAL: 100 FEET




0 25 5p 75 100 MILES

O 50 100 KILOMETERS
I I I


400o


400 -


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 14. Isopach map of Ocala Group (Upper Eocene).





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


the present-day Florida Bay. However, the subsurface geological
information obtained by the writer and other geologists (Puri and
Vernon, 1959, 1960) reveals that the South Florida Basin plunges
west toward the Gulf of Mexico with its axis passing near Sunni-
land and Forty Mile Bend oil fields and trending east-west (fig.
2). Thick Paleocene-Eocene sediments (exclusively carbonates and
evaporites) thin both northward against the Peninsular Arch and
southward toward the present-day Florida Keys (figs. 15 and 16).
More than 4000 feet of nonclastic sediments were accumulated in
this basin during Paleocene-Eocene time.
Basins to the northwest include the Apalachicola and Southeast
Georgia embayments. These were areas of regional downwarping
and were connected by the Suwannee Channel during Paleocene-
Eocene time (fig. 2).
A great amount of valuable information concerning the geome-
try of the deposition basin and related sedimentary environments
can be interpreted from a study of the relationships between the
lithofacies pattern and the isopachs as represented by the combined
isopach-lithofacies maps (See figs. 15-17). The results presented on
these maps clearly identify the regional tectonic elements described
above as the primary controls of the lithofacies pattern and the
isopachs in the area. Two distinct sedimentary facies, land derived-
clastic in panhandle Florida and nonclastic in peninsular Florida,
are well separated by the Suwannee Channel which served as a
natural facies barrier, both lithologic and biologic, throughout al-
most the entire Paleocene-Eocene time. The Peninsular Arch as
outlined by the isopach lines is shown to be a major and prominent
structural feature, and probably originated during Paleozoic time,
persisting throughout the Mesozoic and Cenozoic interval. The
Chattahoochee Arch, considered to be a minor structural feature,
was probably a major controlling factor of the distribution of land
derived-clastic sediments in panhandle Florida during Paleocene-
Eocene time. The South Florida Basin and Apalachicola embayment
are also well defined by the isopach lines.
The regional lithofacies patterns match well with the structural
elements. No trace of the development of Ocala Uplift during
Paleocene-Eocene time is indicated on any of these maps. Such evi-
dence again strongly supports the conclusion that the Ocala Uplift
is a much younger structural feature. No information is provided
by the lithofacies maps regarding the regional distribution of older
(probably Paleozoic) structural elements which are overlain by the
thick Mesozoic and Cenozoic sediments. Nevertheless, the struc-








24 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE





1000

^ 00

0 -1 2 000












S-" 7. - ,
(SS t SH) 0 ZOO














DOLP LS RATI O '**z ^ *''
FACES BOUNDARY .
0. 00





















CONTOUR INTERVALS 500
S 25 50 75 100 MLS 4.
00








DOLO LS A TIOO LS ',















O 50 IqO KILOMETERS I
CHIH SHAN CHEN 1963 NORTHWESTERN UVERSTY







Figure 15. Isopach-lithofacies map of Paleocene-Eocene Series of Florida.
CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY




REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


ES


N


2000


S 2500


EVAP


p


LS
8 0
32 LS


2
DOLO/LS RATIO


CARBONATE/EVAPORITE RATIO

DOLO/LS RATIO

FACIES BOUNDARY


CONTOUR INTERVAL: 500'


0 25 50 75 100 MILES

0 50 100 KILOMETERS
I'


LCHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 16. Isopach-lithofacies map of Paleocene-Eocene Series of panhandle
Florida.


25


DOLO


5s00


8 -


- I--11


'2
4000


10^


o2 o

4S00.


52
oO









26 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


o000


0 oo


/V






/


* *AX.

* 00 0
I. 0 /
* .0 0
0 es
*

~


*
0
*
*
0


S *


0
.
0

0


0 *


SS


2 1
2
SS/SH RATIO


I-2-
- 2 -
---2---I
----- -


CLASTIC / NONCLASTIC RATIO

SS/SH RATIO

FACES BOUNDARY


CONTOUR INTERVAL: 500


0 25 50 75 IO MILES

0 50 100 KILOMETERS


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 17. Isopach-lithofacies map of Paleocene-Eocene Series of panhandle
Florida.





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


tures are considered to be the foundation of the southeastern
Coastal Plain as well as the Florida Platform (fig. 2).

ANALYTICAL PROCEDURES

A total of 164 wells were selected for the study; their locations
are shown in figure 3 and listed in table 1 (see Appendix). Among
these wells 143 are oil tests for which are available complete or
incomplete well samples and electric logs. Generally such tests
penetrate the entire Paleocene-Eocene into Mesozoic and, in some
localities, into Paleozoic strata. In 43 of these wells, electric logs
only were examined, since these wells occur in the vicinity of others
whose lithologic and electric logs were examined in detail by the
writer. The remainder are water wells that penetrate to relatively
shallow depths within the Eocene section and lack electric logs.
Well samples comprise mainly cuttings or chips, with scattered
cores. Only 30 wells have complete samples covering the entire
Paleocene-Eocene section. For the remainder there are partial
records only. Among the latter located in peninsular Florida the
nature of the lithology is interpreted by integrating both the litho-
logic and electric log data.
Samples were obtained from the well sample library of the
Florida Geological Survey and were examined under a binocular
microscope. The electric log of each well was constantly checked
during examination of the samples in order to obtain more reliable
vertical distribution of lithologies since each sample represents an
interval of rock which was generally 20 or 30 feet thick. Samples
were examined in succession, from the surface down, and particular
attention was paid to "first appearances" of different lithologies as
well as faunal assemblages. Each sample was individually studied
for major and minor lithologic constituents, crystallinity of min-
erals and matrix, fossil content and type of fossils, textures, and
other properties.
Regionally, the lithologic changes in peninsular Florida are not
great, so that missing sample intervals could be interpreted sub-
jectively but confidently on the basis of electric logs and by com-
parison with adjacent wells in which well samples were complete.
However, in panhandle Florida where lithologic changes are rather
great, both vertically and laterally, a considerable amount of error
would undoubtedly be introduced in any attempt to estimate major
lithologic types based on the electric log characteristics only. There-


27







28 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

fore, only those wells with complete samples and electric logs were
studied in the panhandle area.
Percentages of limestone and dolomite in each sample were
estimated for use in the construction of lithofacies maps. These
estimates were made by estimating the degree of reaction under
the binocular microscope when each sample was treated with dilute
HC1.
No written lithologic descriptions by earlier workers were con-
sulted and used in this study. This procedure thus assured a
uniformity in lithologic description which could not otherwise have
been achieved. Such descriptions are on file at the well sample
library of the Florida Geological Survey.
Thin sections were also examined, mostly from cores and only a
few from cuttings. Emphasis was placed on examination of tex-
tures, mineralogic composition, relationships between mineral con-
stituents and matrix, and diagenetic phenomena.
Clay minerals were examined by X-ray diffraction techniques.
The methods described by Ostrom (1961) on separation of clay
minerals from carbonate rocks were followed. The so-called slightly
argillaceous dolomite and limestone in the peninsular Florida region
revealed a surprisingly low clay content as well as a lack of other
insoluble residues. Therefore, only calcareous shale samples ob-
tained from wells in panhandle Florida were used in this study.
Oriented slides were made from the clay fraction and were run
untreated in order to obtain the characteristic lines of the clay
present. No other treatments were applied in order to make more
accurate determinations. Quantitative evaluation of any clay min-
eral is extremely difficult (Weaver, 1958a), and therefore estimates
were made on the basis of the relative intensities of the basal (001)
sequences of kaolinite, illite, and montmorillonite and are expressed
as percentages.
Detailed paleontological work was not carried out in this study
owing to the writer's inexperience in this field. However, diagnostic
microfossils foraminiferaa only) described by Applin and Jordan
(1945) and other workers were checked during examination of the
samples under the binocular microscope. Macrofossils such as echi-
noid shells and spines, bryozoans, algal fragments, mollusks, and
other fossils were also examined and recorded, although these are
rare.
Facies maps were constructed on principles summarized in
Krumbein and Sloss (1951, 1963) and Sloss, Dapples, and Krumbein





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


(1960). Major lithologic types pertinent to the investigation were
summed from each stratigraphic unit studied in each well and re-
corded on data sheets. Two distinct sedimentary facies exist both
in the Paleocene-Eocene section and in older rocks. A nonclastic
facies composed strictly of carbonate rocks and evaporites (anhy-
drite and gypsum) dominates the peninsular Florida region and a
plastic facies consisting of sandstone, shale, and limestone domi-
nates the panhandle Florida region. The facies boundary indicated
from the limited well data is rather sharply defined. The following
major lithologies were recorded:
1. Nonclastic facies
Limestone-fragmental, pseudo-oolitic, and fossiliferous,
usually light brown and rather porous. A few highly
fossiliferous limestones are composed almost entirely of
the tepts of microorganisms. Limestones are rarely dolo-
mitic or gypsiferous.
Dolomite-microcrystalline to coarse crystalline, saccha-
roidal textured, brown to dark brown, usually porous and
rarely dense, usually gypsiferous (especially in Paleocene
section), fossiliferous dolomite also present but not
common.
Anhydrite and gypsum-anhydrite is pure white to light
gray or blue, occurs as beds, irregular bands, seams or
veinlets, and commonly associated with microcrystalline
dolomite.
No pure gypsum beds were encountered, gypsum usually
forms irregular thin seams or veinlets, and/or impreg-
nating pore spaces in the dolomite. Selenite is commonly
present.
2. Clastic facies
Sandstone-usually calcareous and glauconitic, poorly con-
solidated, no relatively pure quartz sandstone present.
Shale-green-gray to gray-black, commonly calcareous and
laminated, micaceous and glauconitic, rather soft and
poorly consolidated.
Limestone-commonly fossiliferous to nonfossiliferous, are-
naceous and glauconitic, and argillaceous, rarely dolo-
mitic, cherty limestone not uncommon in certain wells.
These major lithologies were employed as end members and ar-
ranged in several different ways in order to show the regional
lithofacies pattern of each stratigraphic unit studied, which may






30 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

directly relate to the major tectonic elements of the area concerned.
The following are four sets of lithologic end members and ratios
which were employed for the lithofacies analysis:
1. For total area (nonclastic and plastic faces)
AA: sandstone + shale
B: dolomite (+ evaporite)
C: limestone
(B+ C)/AA: carbonate-clastic ratio
B/C: dolomite-limestone ratio

2. For total area (nonclastic and plastic facies)
AA: sandstone + shale
B: evaporite
C: carbonate
(B + C)/AA: nonclastic-clastic ratio
B/C: evaporite-carbonate ratio

3. For peninsular Florida region (nonclastic facies)
AA: evaporite (anhydrite+gypsum)
B: dolomite
C: limestone
(B+C)/AA: carbonate-evaporite ratio
B/C: dolomite-limestone ratio

4. For panhandle Florida region plasticc facies)
AA: dolomite (+evaporite) + limestone
B: sandstone
C: shale
(B+ C)/AA: clastic-nonclastic ratio
B/C: sand-shale ratio
Percentage values of three lithologic components of each strati-
graphic unit studied and two kinds of ratio values which were gen-
erated from those percentage values were computed through the
use of IBM 709 in the Northwestern University Computing Center.
Evaporite percentage maps were also constructed in order to
outline areas of evaporite development. Structure maps were also
made on correlative surfaces within each of the stratigraphic units
studied. Distribution, thicknesses, and correlations between these
units are shown in the lithologic cross sections.





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


DESCRIPTIVE STRATIGRAPHY
GENERAL STATEMENT
In Florida Paleocene-Eocene strata are covered by younger sedi-
ments, with the exception of two areas, the Chattahoochee Arch
in panhandle Florida and Ocala Uplift in peninsular Florida, where
Upper Eocene and Middle to Upper Eocene rocks, respectively, occur
at the surface. These Paleocene-Eocene rocks can be grouped litho-
stratigraphically into the lower part of the Tejas Sequence which
includes all cratonic sedimentary and volcanic rocks of Late Pale-
ocene and younger age in the cratonic interior of North America
(Sloss and others, 1949; Sloss, 1959, 1963).
The Paleocene-Eocene section in Florida comprises, in ascending
order, the Midway Formation and its equivalent, the Cedar Keys
Formation (Paleocene), the Wilcox Formation and its equivalent,
the Oldsmar Limestone (Lower Eocene), the Claiborne Group and
its equivalent, the Lake City and Avon Park Limestones (Middle
Eocene), and the Ocala Group (Upper Eocene). A large part of the
Ocala Group within this section is overlain unconformably by post-
Eocene strata. Units of the entire Paleocene-Eocene section overlie
unconformably the beds of Upper Cretaceous age near basin mar-
gins and up-dip toward the continental interior. However, further
into the Gulf Coast basin, such beds probably are in continuous
succession.
A series of four subsurface stratigraphic cross sections illus-
trates, both vertically and laterally, the stratigraphic relationships
among units of the Paleocene-Eocene section (figs. 18-22). The
datum plane of each cross section is the post-Eocene unconformity.
Descriptions of the lithologic units from which these cross sections
were made are presented later in this chapter. Time-stratigraphic
correlations of Paleocene-Eocene strata in the area are shown in
figure 23. No attempt has been made to revise correlations or to
establish new names, but merely to consolidate terms most fre-
quently used.
Two distinct sedimentary facies, plastic and nonclastic, have
been recognized in each Paleocene-Eocene stratigraphic unit in the
area studied. The regional facies pattern as represented by isopach-
lithofacies maps (figs. 24-26, and pp. 38, 39, and 40) for each strati-
graphic unit clearly demonstrate this division. However, the facies
boundary of successive stratigraphic units does not persistently
remain in the same position, but shifts gradually northward and
northwestward through the time. As is shown in figures 4, 19, and







32 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


/l / /I-I I /



176 8 -j / ..j )
X i
~~1 r'/ 7



1 / i 5 L
17687 / r xis-r-
~ ~~YII S I


/V


SCALE
S25 50 75 100 MILES

0 50 100 KILOMETERS
I


CHIH SHAN CHEN


1963


Figure 18. Index map showing location of cross sections.





,132 4 165 5E s 4S.; 275 5 5
SUN TIDEWATER ASUN ALL FLA LAND L""A. PIONEER nUJMBE HUMBLE N sm G BLA NCHA GULF P ,, GULF
SPCP SEC r CMP 8 GULF 2 E C. C MS M C -I U S5 *OS 36o C FL -M
SEC 24 2 S- 16E SEC 23"eS- IE SEC 16--16S-2E EVIMLeeS I

I to a Mg. / as as. In .


ii rI AfP j



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SDOLO DOLO LS

BFOSSILIF DOLO CHERTY LS
GYGPSIFEROUS DOLO ~FOSSILIF DOLO
GYGPSIFEROUS FOSSILIF DOLO ANHYDRITE
I CHERTY DOLO DOLO ANHYDRITE
FOSSILIF DOLO 00bTI EFOSSILIF DOLO ANHYlDRITE

PEAT 1w"~ "'""" NO SAMPLES AVAILABLE


0
00
200
300


VERTICAL SCALE
(IN FEET)


CROSS SECTION A- A'
PALEOCENE- EOCENE STRATA
FLORIDA J


C^3
W~


Figure 19. Stratigraphic cross section (A-A') of Paleocene-Eocene strata of Florida.





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34 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


gB B7


1669 1005 61
COASTAL m LE20miFLAPIONEER
COASTAL HUMBLE FLA. PIONEER


WF
SEC
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EXPLANATION

SDOLDO U,
i CALCITIC DOLO
[ FOSSILIF DOLO
t GYPSIFEROUS DOLO
l CHERTY DOLO
SLS
SFOSSILIF LS
D GOLO LS
p ARENACEOUS LS
SGYPSIFEROUS LS
G GLAUCO FOSSILIF LS
I ANHYDRITE
Y DOLO ANHYDRITE
a NO SAMPLES
AVAILABLE
!


RIGHT
7 -30
5' K B


I JAMESON I
S- 17E SEC 7-31S-22E
I 109' DF
9 s
--I










































9
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1411 -4086
SmiHUMBLE 0 AMERADA


HAYMAN I
SEC 12-3S-33E
72' OF
S P Ras


100 1





























CROSS SECTION B-B'
PALEOCENE-EOCENE STRATA
FLORIDA


COWLES I
SEC 19-36S-40E
31' OF
s rES


10
200
300
400
500
VERTICAL SCALE
(IN FEET)


I--A


Figure 20. Stratigraphic cross section (B-B') of Paleocene-Eocene strata of

Florida.


--


*\








i






3455 2935 2913 1610
MEARS- 30m 45mi TEMPL
WILTON-ARMOUR SUN A.R. TEMPLE?5 BYERS
SEC 10-2N-27 SEC IB-3N-22W SEC 30-2N-1ISW SEC 31-2N-9W
45' DF 173 F 148' DF 266' DF
SP n's op 'prr n


1768 1854
40mi m L
OLES & NAYLOR COASTAL
FLA POWER I LARSH I
SEC G5-2N-3W SEC I-2S-3E
200' DF 51' OF
sp fts sp lit$


C'
1596 1832 1500 336
Sm, HUNT 4ore, SUN 25M, HUNT 28 ST. MARY'S RIVER
GIBSON 2 SAPP I HUNT FEE I HILLIARD I
SEC 6-IS-IOE SEC 24-2 S-16E SEC 21- IN-20E SEC 19-4N-24E
107' DF 138' DF 130' DF 99' DF
S SUWAN
.r II, 1 rNEE LS


CROSS SECTION C C
PALEOCENE- EOCENE STRATA
FLORIDA


CA~ ILC SS
5 GLAUGO CALC SS
A RGIL 'SS


SGLAUCO ARGCIL SS
SGLAUCO SS


CA CLC SH
GLAUGUUO GLC SM.
W01000 001
POLO021SC


E X PLAN ACTION "

S CALCITIC DOLO GLAUOARENAEOUS
l FOSSILIF DOLO ,At LS LS
S OLITIC oOLO GLAUCO ARENACEOUS
| GYPSIFEROUS DOLO | GLAUCO FOSSILIF LS
SY 2FOSOSIIF DOLO FOSSILIF DOLO LS
ARENACEOUS DOLO ARGIL LS
6 LS GLAUGO LS
| FOSSILIF LS F GYPSIFEROUS FOSSUF LS.
SENACEOUS LS E 0mERTY FOSSIL LS
SYPsYFtrOUS LS No SAMPLES
RT LS am A LALALE


Figure 21. Stratigraphic cross section (C-C') of Paleocene-Eocene strata of Florida.


0
z
ct-



H
0



H
E:
c3




H




z

0
cj
t-3




X
cr



-
0C

cc


cHIH SHAN CHEN 1963







X-26 1513 3650 1610
20 mi. 20 mI 30l. 3Omi
R. W. WILLIAMSo S. W BREEDING THOMPSON BYERS
WHITFIELD I COATES I DEAL I HARDAWAY I
SEC 18-3N-26E SEC. 25- 7N- 15W SEC 4-3N-14W SEC. 31-2N- 9W
270' DF. 200' DF 43' DF 266' DF.

c- L +-1WAl


EXPL NATION

B ss


F* GLAUCO SS

1 SH
E CALC SH


1468 1455
PURE 25ml PURE
McMILLAN I HOLLINGER I
SEC 25-4S-IIW SEC 12- 9S-IIW
48' DF. 5' D.F.
V I. .-I I9 , I, s.


Figure 22. Stratigraphic cross section (D-D') of Paleocene-Eocene strata of Florida.






a Florida
SStage Alabama Georgia
. k (southern)
__Panhandle Peninsula


Byram Fm. Suwannee Ls. Suwannee Ls. Suwannee Ls.
Marianna Ls. Byran Fm. Byran Fm.
Red Bluff Clay Marianna Ls. Marianna Ls.

IJ-I ? J1 ]lli [II IJ I7 I I L ]I- 1 1111


Yazoo Clay
Ocala Ls.


I
0 a)
tko C:
-r4 Q)
Os
r-4U
0












El)
0


IITT1-177


Gosport Fm.
McBean Fm.
Tallahatta Fm.


co P4
0o
$4
0 0


Crystal River Fm.
Williston Fm.
Inglis Fm.


I.E 111 11 III*_I 1 1 1 1


Undifferentiated
Claiborne
Group


Avon Park Ls.

Lake City Ls.


Hatchetigbee Fm. Hatchetigbee Fm
Tuscahoma Fm. Tuscahoma Fm. Wilcox Fm. Oldsmar Ls.
Nanafalia Fm. Nanafalia Fm.
& Salt Mt. Ls.



Naheola Fm.
Porters Creek Fm Midway Fm. Midway Fm. Cedar Keys Fm.
Clayton Fm.



Selma Chalk & Providence Fm. Beds of Navarro Age Lawson Ls.
Ripley Fm. Cusseta Fm. Beds of Taylor Age Beds of Taylor


Age


Figure 23. Correlations of Paleocene-Eocene strata.


C;
*r-l
4J
0
4


Vicksburg


Jackson


Claiborne


Sabine


Midway


Moodys Branch
Fm.


Gosport Fm.
Lisbon Fm.
Tallahatta Fm.


I W)
oc
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Ns


44
"-4


CO
$41
u
u


Navarro


,,-,._~_ ,,, _._. ~,,, ,,-, ,,


Age


I l l


I I I I I I I I l I I I I I I I I I I I I --I I I l I11








38 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE







0 z 0









I 16
v^o o








.1 '4 lb
I S

























EVAP CARB --- -
o4 6 (LS. 4DOLO)












EVAPORITE CARBONATE RATIO


-4-- NONCLASTIC PLASTIC RATIO
(as SH).





















---1 4--- EVAPORITE CARBONATE RATIO

FACIES BOUNDARY
20* .
17-0














CONTOUR INTERVAL. 200 a











EVA POR CAR 0 KILOMETERS
4 ,NONCLASTIC CLATICRA






















CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY









Figure 24. Isopach-lithofacies map of the Paleocene Series of Florida.
Fu2 s h t
4~i NOCATC CATI AI ti ..
-~ ~~~~, ,,4 EVPRT ABOAERT










CHIH SHA CHE 19:3 ORTHESTRN UIVESIT

Figre24 Isopach----L-,-lihfce mapE of th aeceeSresoFoida.







REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


* *
0. *


NONCLASTIC

FACES


* -:tr -^ ^


25 LS
16


DOLO/LS RATIO


4 -- CARBONATE /EVAPORITE RATIO

I DOLO/LS RATIO

-I-I-I---- FACES BOUNDARY


600
1600


CONTOUR INTERVAL: 200


S 2 5 ~0 75 190 MILES

5,0 9I0 KILOMETERS


SCHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY

Figure 25. Isopach-lithofacies map of the Cedar Keys Formation (Paleocene
Series) of peninsular Florida.


39


N


DOLO


"









40 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


NONCLASTICS


*


0


0


ss


2 16
SS/SH RATIO



- 4- CLASTIC/NONCLASTIC RATIO

--1/2--- SS/SH RATIO

----- FACIES BOUNDARY



CONTOUR INTERVAL: 200


0 25 50 75 100 MILES

0 50 100 KILOMETERS



SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 26. Isopach-lithofacies map of the Midway Formation (Paleocene
Series) of panhandle Florida.


0


y.0


* or
S*




o







0


0 0


0
0
0

0


CHIH





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


21 the nonclastic facies in peninsular Florida has encroached steadi-
ly upon the plastic facies in panhandle Florida and its adjacent
areas, spreading northward and northwestward during successive
stages. Near the end of Late Cretaceous time, the nonclastic facies
had spread over all of the peninsular Florida region and a part of
southern Georgia. The two facies tracts were separated by the
so-called Suwannee Channel, a rather narrow and elongate negative
structural feature which is considered to have been characterized
by relatively deeper water and moderately strong currents passing
through it. Such currents within the channel could prevent trans-
port of terrigenous sediments across the channel into peninsular
Florida during the time from Late Cretaceous to early Middle
Eocene or Upper Eocene (figs. 4-6). Besides the major influence of
the Suwannee Channel, however, some other factors may have con-
tributed to the development of such marked facies difference. An
example occurred during Paleocene-Eocene time when northwesterly
prevailing long-shore currents probably existed along the coast re-
gion of the panhandle; only a small amount of plastic sediments
was actually contributed from the source areas, the southern
Appalachian region, to the loci of deposition; and only a few
streams were available for transporting the plastic sediments.
CEDAR KEYS AND MIDWAY FORMATIONS
PRE-MIDWAYAN UNCONFORMITY
An important unconformity separates basal Paleocene sediments
and Upper Cretaceous rocks throughout most of the Gulf Coastal
Plain (Rainwater, 1960).
Applin and Applin (1944) have stated that in the vicinity of
Tallahassee, Paleocene strata rest unconformably on beds of Taylor
age with the Navarro equivalent and even upper beds of Taylor age
being absent.
In Levy and Citrus counties of peninsular Florida, Vernon
(1951) also reported an unconformity at the top of the Upper
Cretaceous as evidenced by the presence of gray, chalky, limestone
pebbles in the base of the Cedar Keys Formation (Paleocene). Un-
conformable relationships in northern and central Florida seem to
be demonstrated.
In southern Florida, however, the writer sees no conclusive
evidence suggesting an unconformity between the Cedar Keys
Formation and Lawson Limestone (late Upper Cretaceous). Litho-
logic and faunal differences are quite distinct at stratigraphic posi-
tions well above and well below the formational contact, but the






42 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

contact itself is arbitrarily chosen in a transitional succession.
Thus, the sub-Paleocene unconformity appears to pass into an
unbroken sequence in the South Florida Basin.
CEDAR KEYS FORMATION
The Cedar Keys Formation was originally applied by Cole
(1944) to Paleocene (his Lower Eocene) rocks of nonclastic facies
in the subsurface of northern and peninsular Florida. According to
Cole:
The term Cedar Keys formation is designated to cover the
rocks encountered in wells in peninsular and northern Florida
from the first appearance of the Borelis fauna to the top of
the Upper Cretaceous. The Cedar Keys formation is unques-
tionably the stratigraphic equivalent of the Midway forma-
tion of the Gulf Coast area.
However, boundaries of the Cedar Keys Formation as currently
used by the Florida Geological Survey (Vernon, 1951; Puri and
Vernon, 1959) and by other southeastern Coastal Plain geologists
(Applin and Applin, 1944; Toulmin, 1955) are slightly modified
from those originally proposed by Cole. The top of the Cedar Keys
Formation is marked by a distinct lithology consisting mainly of
gray, microcrystalline, slightly gypsiferous and rarely fossiliferous
dolomite that is relatively easily recognized on electric logs. This
contact is generally near to but never below the top of the range
zones of Borelis gunteri and Borelis floridanus. The base of the
Cedar Keys is defined lithologically by the presence of the under-
lying Lawson Limestone (latest Upper Cretaceous) which is com-
posed chiefly of pure, clean, very light brown and fine crystalline
dolomite and/or chalky dolomitic limestone. The Cedar Keys For-
mation as considered here rests unconformably, at least locally if
not regionally, on the Lawson Limestone and is conformable with
the overlying Oldsmar Limestone (Lower Eocene).
The Cedar Keys Formation consists mostly of dolomite and
evaporites (gypsum and anhydrite) with a minor amount of lime-
stone and shows distinctive lithologic and faunal characteristics
quite different from rocks above and below. The dolomite is light
gray, slightly porous to porous, rather hard, microcrystalline to
very fine crystalline, and nonfossiliferous to fossiliferous. Anhy-
drite generally forms beds, nodules, and lenses and is interbedded
with dolomite. Gypsum commonly fills pore spaces within the dolo-
mite beds and occurs as thin irregular streaks or seams in dolomite.
A relatively large portion of dolomite in the formation has been
impregnated, partially or completely, with gypsum. No halite or





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


potash minerals were found by the writer in this study and none
has been reported in the literature. These evidences suggest strong-
ly that the complete marine evaporite cycle is not represented in
these strata.
The upper part of the formation is composed mainly of dolomite
which is gray, more or less impure (probably contaminated by
organic matter), slightly gypsiferous to gypsiferous, generally
microcrystalline, rarely fossiliferous, and slightly calcitic in part;
this distinctive lithologic character marks the top of the Cedar
Keys Formation and shows relatively low resistivity curves on
electric logs. The lower part of the formation is composed mainly
of non-fossiliferous to fossiliferous and gypsiferous dolomite and
anhydrite beds. Gypsiferous (or anhydritic) dolomite is commonly
interbedded with dolomitic anhydrite and/or anhydrite beds. The
vertical repetition of the pair of dolomite and anhydrite beds which
represents each of the major but incomplete marine evaporite
cycles occurring in the lower part of the formation is more common
downdip toward the South Florida Basin than updip over the Penin-
sular Arch. Laterally, away from the basin center, these anhydrite
beds are gradually replaced by the carbonates. Such vertical and
lateral lithologic variations of the Cedar Keys Formation are clearly
demonstrated on the lithological cross section A-A' as shown in
figure 19. Faunally, the formation is characterized by the presence
of the Foraminifera Borelis gunteri and Borelis floridanus.
The Cedar Keys Formation is widely developed throughout
peninsular and northern Florida, and near the Georgia boundary
(figs. 24-25). In the other parts of the Gulf Coast, this formation
is considered by the Coastal Plain geologists to be the marine and
deltaic plastic equivalent of the Midway Group.
Figure 24 is the isopach-lithofacies map of the Paleocene Series
including both the Cedar Keys Formation in peninsular Florida
and the Midway Formation in panhandle Florida. Figure 25 is the
isopach-lithofacies map of the Cedar Keys Formation alone. Differ-
ent lithologic end members are employed in constructing these two
maps in order to show the most important regional lithofacies pat-
terns. In northern Florida, near the Georgia border, and along the
present-day Florida Keys, the Cedar Keys is composed mainly of
fossiliferous to nonfossiliferous, very fine crystalline dolomite and
calcitic dolomite with a minor amount of gypsum and anhydrite.
However, slightly dolomitic, fossiliferous and nonfossiliferous lime-
stones become dominant near or along the facies boundary lying at
the northern and northwestern end of the peninsula and stretching






44 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

northeasterly as a narrow belt from southeastern Georgia to pan-
handle Florida and the Gulf of Mexico (fig. 25). In central and
southern Florida, the formation is essentially nonfossiliferous to
fossiliferous and microcrystalline dolomite, gypsum and anhydrite.
The relatively high evaporite content of the formation as shown on
the evaporite percentage map (fig. 27) is developed in such areas
as the western part of the northern and central Florida and almost
the entire southern Florida region where the South Florida Basin
was located. The regional lithofacies pattern also indicates that the
area with high evaporite content would undoubtedly be shown to
extend farther to the continental shelf regions on both sides of the
peninsula if more subsurface geological information were available
for these regions.
The thickness of the Cedar Keys varies considerably, from less
than 300 feet on the crest of the Peninsular Arch in northern Flor-
ida (Suwannee and Lafayette counties) to more than 2000 feet in
those counties (Charlotte, Collier, Hendry, Lee, and Monroe) around
the Sunniland oil field in southern Florida.

MIDWAY FORMATION
In western and central Alabama, the Midway (Paleocene Series)
is used as a group name which, as observed at the outcrop and sub-
surface, can be separated into three formations; in ascending order,
the Clayton, the Porters Creek, and the Neheola (Toulmin, 1955).
However, in southeastern Alabama the subsurface geologic infor-
mation reveals that geologists have had difficulty, both lithological
and faunal, in subdividing the Midway Group and in correlating it
with the rocks of the same group in western and central Alabama.
Toulmin and LaMoreaux (1963), on the basis of a detailed strati-
graphic study along the Chattahoochee River, state that the Terti-
ary formations recognized in the river section are those of the
standard Alabama stratigraphic section. The Midway Group, how-
ever, is represented only by the Clayton Formation.
In panhandle Florida, the writer, as well as many other geolo-
gists who have worked in the same area, is unable to differentiate
the Midway Group on the basis of well cuttings, electric logs, and
fossils; and, therefore, the unit is here treated as a formation.
Generally, the Midway is overlain, probably conformably, by the
Wilcox Formation in the panhandle, although the regional distribu-
tion of these two units as shown at the surface (fig. 1) indicates
that the Wilcox overlies the Midway unconformably in southeastern
South Carolina. The Midway is underlain unconformably, at least







REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


* *



S4.


10 -4

15


CONTOUR INTERVAL: 5%


0 25 5p 75 100 MILES

0 50 100 KILOMETERS
I I i


CHIH SHAN CHEN


Figure 27. Evaporite percentage map of the Paleocene Series of Florida.


45


I/V


0






46 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

locally, by beds equivalent in age to Navarro and Taylor formations
of the Selma Group (Upper Cretaceous).
The Midway Formation is composed mainly of dark gray to dark
green-gray, micaceous and slightly glauconitic, laminated and cal-
careous shale with a minor amount of thin bedded argillaceous and
fossiliferous limestone and glauconitic and calcareous sandstone.
However, limestone becomes dominant southeastward near the
facies boundary, while the sandstone exists only locally as pene-
trated in those wells located on the crest of the Chattahoochee
Arch. Lithologically, the upper boundary of the formation has been
placed at the top by the first appearance of rather compact and
laminated calcareous shale, or glauconitic and calcareous shale, or
argillaceous and/or cherty limestone. The base is placed at the top
of a rather thick chalky fossiliferous limestone of Upper Cretaceous
age that is well shown on the electric logs and can be traced later-
ally for a long distance (fig. 21). These lithologic boundaries have
been proved applicable to study of subsurface geology in panhandle
Florida where the faunal control is rather poor or not available.
Faunally, a characteristic assemblage zone close to that of the type
Tamesi of Mexico (Applin and Applin, 1944; Applin and Jordan,
1945) has been reported in the lower part of the Midway Formation
in some wells located in Jackson, Jefferson, Wakulla, and Washing-
ton counties of Florida.
The Midway Formation underlies panhandle Florida and extends
widely throughout the southeastern Coastal Plain and Gulf Coast.
Regionally, the vertical and lateral changes of lithologic character
and thickness of the formation are rather great as demonstrated
on the isopach-lithofaces maps of figures 24 and 26. The lithofacies
pattern indicates that the relatively coarser plastic sediments, such
as glauconitic and arenaceous shale and glauconitic and argillaceous
sandstone, are more dominant around the Chattahoochee Arch than
elsewhere in the panhandle region. Further, calcareous shale is a
major lithologic component over most of the panhandle region,
except near the facies boundary in the southeastern panhandle area
where limestone is predominant.
The Midway is relatively thin (less than 200 feet) near the
facies boundary and updip toward the inner margin of the Coastal
Plain. However, it thickens considerably southwestward toward the
Gulf. In Escambia County, Florida the total thickness of the unit
reaches more than 1000 feet.
The most important geologic information revealed from the





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


study of the isopach-lithofacies maps (figs. 24-26) and structure
map (fig. 9) is summarized as follows:
1. The clastic-nonclastic facies boundary is rather sharply de-
fined as far as can be determined by the limited well data.
2. Two separated evaporite basins are outlined in the penin-
sular Florida region, probably extending beyond the present-
day land area of the peninsula to the continental shelves
on both sides.
3. The amount of plastic sediments increases updip toward the
inner margin of the Coastal Plain and decreases downdip
toward the Gulf. However, the amount of calcareous material
within the plastic facies increases steadily southeasterly to-
ward the facies boundary, and plastic sediments are entirely
absent in peninsular Florida.
4. Facies and isopach strikes are generally concordant except
in northern and central peninsular Florida.
5. Regionally, the structure and isopach strikes are markedly
parallel.

OLDSMAR LIMESTONE AND WILCOX FORMATION
OLDSMAR LIMESTONE
The Oldsmar Limestone was originally applied by Applin and
Applin (1944) to the nonclastic rocks of Lower Eocene age in
peninsular and northern Florida. This unit includes the interval
that is marked at the top by the presence of abundant specimens of
Helicostegina gyralis, and that rests on the Cedar Keys Limestone.
Four assemblage zones were recognized in the formation by them.
The formation as defined by the Applins is a biostratigraphic unit.
A lack of complete sample sets raises difficulties in selecting
lithologic markers to define the upper and lower boundaries of the
Oldsmar. Lithologically, however, the Oldsmar is quite different
from the underlying Cedar Keys Formation, but not readily differ-
entiated from the overlying Lake City Limestone. The top of the
Oldsmar is here defined by the presence of a chalky white to light
brown, rather pure, finely fragmental and fossiliferous limestone
unit which is overlain by a thick dolomite section of the Lake City
Limestone. The base of the Oldsmar is marked by a thick, dark
brown, rather pure and clean, and fine to coarse crystalline dolo-
mite unit which shows marked lithologic differences with the un-
derlying Cedar Keys Formation. The writer considers that the
formation has conformable relationships with the strata lying






48 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

above and below. The Oldsmar Limestone is composed essentially
of dolomite and limestone with evaporites (gypsum and anhydrite)
as a minor component; a minor amount of white and dark brown
chert forming irregular lenses is also penetrated in certain wells
scattered on the northern part of the Peninsular Arch. The lime-
stone is usually light brown to chalky white, rather pure, porous,
and fossiliferous. Reef-like limestone beds have been encountered
in two wells located in those counties (W-1596, Madison County and
W-2775, Suwannee County) in northern Florida. Interbedded with
limestone are brown to dark brown, rather porous, fine to coarse
crystalline, commonly saccharoidal textured dolomite beds. Gypsum
and anhydrite are rare as regular beds but form irregular bands
and veinlets or occupy pore spaces. Exceptions are noted in a few
wells located in those counties (Glades, Highlands, and Okeecho-
bee) in southern Florida where anhydrite and gypsiferous dolomite
are dominant in the lower part of the formation (fig. 19). The
amount of evaporite present in the formation is significantly less
than in the underlying Cedar Keys Formation. Faunally, the Olds-
mar is characterized by the presence of abundant foraminifers of
Helicostegina gyralis and other recognizable guide foraminifers.
The Oldsmar Limestone is well developed and widely distributed
throughout peninsular and northern Florida and a part of south-
eastern Georgia (figs. 28-29). The formation is considered to be
the marine and deltaic plastic equivalent of the Wilcox Group in
the most of the Gulf Coast region.
Figure 28 is the isopach-lithofacies map of the Sabine (or Wil-
cox) Stage in the entire Florida region, including the Oldsmar
Limestone in the peninsula and the Wilcox Formation in the pan-
handle (fig. 30). Figure 29 is the isopach-lithofacies map of the
Oldsmar Limestone alone. These two maps are constructed with
different lithologic end members so as to show the regional relation-
ships of pertinent facies.
The regional lithofacies pattern of the Oldsmar Limestone (figs.
28-29) indicates rather clearly the high dolomite content encount-
ered on the crest of the Peninsular Arch, relatively high evaporite
content in southern Florida, and high limestone content away from
the arch and removed from those areas having high evaporite
content. The areas with relatively high evaporite content as out-
lined by the carbonate-evaporite ratio lines (fig. 29) as well as
shown on the evaporite percentage map (fig. 31) are considerably
smaller and better defined than those of the Cedar Keys Formation
(figs. 24, 25, and 27). In northern Florida near the facies boundary,







REGIONAL LITHOSTRATIGRAPHIC ANALYSIS 49

'00 600 10 0


















CLASTICS
(SS + SH)














DOLO / LS RATIO


-4- NONCLASTIC /CLASTIC RATIO

I DOLO / LS RATIO \000

I-- FACIES BOUNDARY o


CONTOUR INTERVAL: 200' 00


0 25 50 75 100 MILES

0 50 0 KILOMETERS


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 28. Isopach-lithofacies map of the Sabine (or Wilcox) Stage of Florida.
i~IL'-AA

.iCLASTIOS
(SS +: SH)
:i32
.I ,irij~.~~.::ljf~.::$










































Figure 28. Isopach-lithofacies map of the Sabine (or Wilcox) Stage of Florida.








50 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


.-- NONCLASTI C

*' *--FACIES
o o---j









0000




060



800
LIi








DOLO LS I 8o
2 8 I
DOLO/ LS RATIO


8 CARBONATE/ EVAPORITE RATIO

-I DOLO /LS RATIO 0 \0

--I--I FACES BOUNDARY 'o


CONTOUR INTERVAL: 200' o00


0 25 5,0 7P 100 MILES %

5,0 IO0 KILOMETERS 00



CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY

Figure 29. Isopach-lithofacies map of the Oldsmar Limestone (Sabine or
Wilcox Stage) of peninsular Florida.






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


PLASTIC
FACES


77400
Z w --600


/7


NONCLASTICS

18c
Vm


0


*


0 *


* *


SS


SS/ SH RATIO


- 8- PLASTIC / NONCLASTIC RATIO
SS/SH RATIO
-I-I-I---I- FACIES BOUNDARY


CONTOUR INTERVAL: 200


0 2 5 0 75 100 MILES
0 5,0 Iq0 KILOMETERS


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY

Figure 30. Isopach-lithofacies map of the Wilcox Formation (Sabine or
Wilcox Stage) of panhandle Florida.


*
0
*


**








52 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


A/


* /

) *,
i* 0


. .** --
0 o
0


CONTOUR INTERVAL: 5%

0 25 5p 75 100 MILES

0 50 100 KILOMETERS
I i I


0 0


CHIH SHAN CHEN

Figure 31. Evaporite percentage map of the Sabine (or Wilcox) Stage of
Florida.





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


limestone becomes predominant and grades northwesterly and
northerly into the plastic faces of panhandle Florida and southern
Georgia (figs. 19, 21, and 28). As has been shown on the isopach-
lithofacies maps, the writer believes that these carbonate rocks ex-
tend to the continental shelf regions on both sides of the peninsula
and to the Bahamas.
The thickness of the Oldsmar Limestone varies from less than
400 feet on the crest of the Peninsular Arch to more than 1200 feet
in southern Florida. The rather irregular isopach pattern shown in
peninsular Florida (figs. 28-29) may be due to the intensive dolo-
mitization which has destroyed fossils and altered the original tex-
ture of the limestone such that it is difficult to define the upper
boundary of the formation (Vernon, 1951). In addition, cuttings
and cores of this unit are commonly incomplete and the top of the
unit is not easily recognized on electric logs.
WILCOX FORMATION
The simplified regional geological map of the southeastern
United States as shown in figure 1 indicates that Lower Eocene
strata (Wilcox Group) crop out in a narrow and convex gulfward
belt extending from the east side of the Mississippi Embayment
across southern Alabama into western Georgia. Farther east, these
strata are overlapped by Middle Eocene and younger sediments.
Three formations of the Wilcox Group, in ascending order, the
Nanafalia, the Tuscahoma, and the Hatchetigbee, have been rec-
ognized in Alabama and Georgia, but these formations are undis-
tinguishable in the subsurface of panhandle Florida and the unit
is here treated as a formation. No distinctive geological evidence
of unconformable relationships between the Wilcox Formation and
the rocks lying above and below in panhandle Florida is recognized,
although such unconformable relationships among these rocks are
demonstrated in the outcrop belt to the north.
The top of the Wilcox is generally drawn on the first appear-
ance of gray to green-gray and slightly calcareous shale; or gray,
glauconitic, arenaceous and calcareous shale; or brown and essenti-
ally nonfossiliferous limestone. The base of the unit is defined by
the top of the Midway.
Lithologically, the Wilcox Formation in panhandle Florida con-
sists of glauconitic and calcareous sandstone; light brown, glau-
conitic and arenaceous limestone; and green-gray, micaceous and
calcareous, and glauconitic and silty shale. Highly fossiliferous
limestone is not common even in the dominant limestone section.
Siliceous and/or cherty, argillaceous limestone is encountered in






54 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

those wells penetrating a dominantly limestone section. Sandstone
and shale are dominant in northern and western panhandle Florida,
while limestone is a major lithologic constituent southeastward
toward the coast and the facies boundary (figs. 21, 22, and 30).
Marine and deltaic plastic sediments in panhandle Florida and
southern Georgia grade southeastward into nonclastic facies repre-
sented by the Oldsmar Limestone. These two distinctive sedi-
mentary facies, though probably gradational, are rather sharply
defined; they were probably originally separated by the Suwannee
Channel. The faunas recognized in the panhandle region show clear
relationships with Wilcox faunas described from the other parts of
the Gulf Coast (Applin and Applin, 1944; Toulmin, 1955), however,
they are remarkably dissimilar to those found in peninsular Florida.
The regional distribution of major lithologies of the Wilcox
Formation in panhandle Florida is shown in figures 28 and 30.
These maps indicate that the amounts of plastic sediments decrease
rapidly southeastward toward the peninsular Florida and continen-
tal shelf region where they are almost completely absent. Sediments
of the Wilcox vary in thickness from less than 200 feet near the
facies boundary in the southeast margin of the panhandle to near
1000 feet southwestward toward the Gulf.
From a joint investigation of regional isopach-lithofacies maps
(figs. 28-30) and the structure map (fig. 10) of the Wilcox Forma-
tion and Oldsmar Limestone in Florida, the following relationships
are apparent.
1. The amounts of plastic sediments increase systematically
and rapidly northward from panhandle Florida to southern
Alabama and Georgia, while the amounts of nonclastic sedi-
ments increase rapidly southeastward toward the peninsula
where plastic sediments are almost completely absent.
2. Dolomite is a dominant lithology for almost the entire penin-
sula, while limestone is more common in northern Florida
and near the facies boundary.
3. The areas of the evaporite basins as well as their evaporite
content are greatly reduced in comparison with those of the
Paleocene section.
4. Facies and isopach strikes are almost parallel in panhandle
Florida, but they are rather discordant, at least locally, in
peninsular Florida.
5. Regionally, structure and isopach strikes parallel each other
quite closely.






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


LAKE CITY AND AVON PARK LIMESTONE AND
UNDIFFERENTIATED CLAIBORNE GROUP
GENERAL STATEMENT
The Claiborne Stage (Middle Eocene) in panhandle Florida and
the northern and western Gulf Coast region is represented mainly
by sandstone, shale, and limestone. However, in northern and penin-
sular Florida, the Claiborne is composed almost entirely of dolomite
and limestone with a minor amount of evaporite and a laminae or
thin beds of peat. These two sedimentary facies are quite different,
both lithologically and faunally, although certain faunal assem-
blages common to both facies support the time-stratigraphic cor-
relation (Applin and Applin, 1944). On the basis of lithology and
faunal differences, Applin and Applin (1944) recognized three for-
mations in the Claiborne Group in peninsular Florida; in ascending
order, Lake City Limestone, the Tallahassee Limestone, and the
Avon Park Limestone. The Tallahassee Limestone (and an equiva-
lent nonfossiliferous limestone) is confined to limited areas in the
vicinity of Tallahassee and in the counties of northern peninsular
Florida.
The plastic sediments of the Claiborne Group crop out in west-
ern and southern Alabama and consist chiefly of glauconitic sand-
stone, calcareous and arenaceous shale, and fossiliferous, glauconitic
and argillaceous limestone. Three formations have been recognized;
in ascending order, the Tallahatta Formation, the Lisbon Forma-
tion, and the Gosport Sand. However, farther downdip toward the
Gulf, the entire Claiborne Group becomes calcareous, and it is
rather difficult to subdivide it into the formations of the outcrop
area.
No attempt is made by the writer in this study to subdivide the
rocks of plastic facies of the Claiborne Group in panhandle Florida,
although, in general, the unit is divisible into lower and upper por-
tions (figs. 21 and 22). For the purposes of the present study the
unit is here treated as an undifferentiated group. However, in pen-
insular Florida the Claiborne Group is subdivided into two forma-
tions-the Lake City Limestone below and Avon Park Limestone
above. A nonfossiliferous carbonate bed, an equivalent of the
Applins' Tallahassee Limestone, is here considered as adolomitized
Part of the Avon Park Limestone and/or Lake City Limestone
(Vernon, 1951) in which diagnostic microfossils have been
destroyed.
The Lake City Limestone as originally defined by Applin and






56 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

Applin (1944) is primarily based on faunal zones, but it is also
a distinctive lithologic unit (Vernon, 1951.) Faunally, the top of
the Lake City Limestone is marked by the first appearance of
Dictyoconus americanus, and the formation is further characterized
by many other diagnostic foraminifers such as Amphistegina
lopeztrigoi, Discocyclina (Asterocyclina) monticellensis, Fabularia
gunteri (Applin and Jordan, 1945). The Avon Park Limestone also
has a distinctive faunal assemblage, mostly foraminifers, including
Coskinolina floridana, Lituonella floridana, Dictyoconus cookei,
and many other microfossils (Applin and Applin, 1944; Applin and
Jordan, 1945; Cole, 1942, 1944; and Cooke, 1945).
The Lake City Limestone generally rests conformably upon the
Oldsmar Limestone, but disconformable relationships may exist
locally. The Lake City Limestone is overlain unconformably by the
Avon Park Limestone according to Vernon (1951). However, the
writer considers that such unconformable relationships exist only
rather locally. In other words, the unconformable relationships are
more apparent on tectonic shelves and positives but are less appar-
ent toward basin centers. The unconformable relationships between
the Avon Park Limestone below and the Ocala Group and the post-
Eocene strata above are quite obvious. The stratigraphic relation-
ships between the Claiborne Group and the strata lying above and
below as found in panhandle Florida are about the same as in the
peninsular region, although these two depositional environments are
considerably different from each other in terms of the sedimentary
conditions under which the plastic and nonclastic sediments were
formed.
LAKE CITY LIMESTONE
The Lake City Limestone (early Middle Eocene) was originally
named by Applin and Applin (1944) to designate a dark brown and
chalky limestone facies in northern and peninsular Florida and to
differentiate it from an equivalent plastic facies in panhandle Flor-
ida and the other parts of the southeastern Coastal Plain. The
Applins established the top of the unit at the first appearance of
Dictyoconus americanus. However, this unit as originally defined
is a biostratigraphic unit rather than a rock unit.
Examination of well cuttings from those wells located in north-
ern and central peninsular Florida reveals a relatively thin but
rather highly carbonaceous unit consisting mainly of laminae or
thin beds of peat, intercolated with dark brown to brown-black
carbonaceous limestone and dolomite that usually overlies the





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


fossiliferous limestone in which Dictyoconus americanus is com-
mon. This thin and highly carbonaceous unit is quite persistent
over most of northern and central peninsular Florida (fig. 32)
where it provides a useful lithologic key bed at the top of the Lake
City Limestone. This marker gradually thins both toward southern
Florida and northerly near the faces boundary along the northern
margin of the peninsula. However, near the facies boundary and in
southern Florida, the key bed is replaced by a brown to dark brown,
fragmental and fossiliferous limestone which contains Dictyoconus
americanus and other foraminifers and is overlain by the basal
dolomite unit of the Avon Park Limestone. This necessary modifica-
tion of the top of the formation brings it into conformity with the
Stratigraphic Code (1961) and has only very minor effect on the
thickness of the formation as originally defined. Generally, the base
of the Lake City Limestone is marked by a thick unit consisting
essentially of brown to dark brown, rather porous, fine crystalline
dolomite which conformably overlies the Oldsmar Limestone. This
relationship is revealed in incomplete well samples obtained from
widely scattered wells and prevails over most of peninsular Florida.
Near the facies boundary and in the southernmost part of the pen-
insula a thick, brown, fragmental and fossiliferous limestone bed
marks the base of the formation (figs. 19 and 20).
Lithologically, the formation is composed essentially of highly
fossiliferous (mostly foraminifers) limestone and brown to dark
brown dolomite with a very minor amount of evaporites and car-
bonaceous material (figs. 19-21). The limestone is commonly light
brown to brown, fragmental, highly fossiliferous to microcoquina-
like, and slightly carbonaceous and cherty. Some highly fossilifer-
ous limestone beds consist almost entirely of foraminifers and other
microfossils. Reef-like limestone beds have been encountered in the
well (W-890, Nassau Co.) located in northern Florida. All stages
of dolomitization, from minute dolomite crystals in the matrix to
pure dolomite, can be seen. The dolomite is generally brown, rather
porous, finely crystalline, and saccharoidal in texture. Unaltered
microfossils and their molds are not uncommon, especially in the
calcitic dolomite or dolomitic limestone. Traces of fragmental tex-
ture and microfossil relics are visible under the petrographic micro-
scope. Gypsum is commonly present as thin seams or veinlets and
fills the pore spaces within the dolomite. Selenite is quite common
in cavities and vugs, but anhydrite is very rare. The amount of
evaporites is almost negligible as far as the gross lithology of
the formation is concerned. Thin peat and carbonaceous dolomite







58 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


* *0
.

0 0
0

0


0 0


/I


0 25 50 75 100 MILES
0 50 100 KILOMETERS
I I i


CHIH SHAN CHEN

Figure 32. Regional distribution of highly carbonaceous dolomite and lime-
stone interbedded with thin streaks or thin beds of peat in northern and central
Florida near the end of early Middle Eocene time (shaded area).





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


and/or limestone beds are generally present in the upper part of
the formation. Dark, carbonaceous dolomite and limestone are com-
monly associated with laminae or thin beds of peat. Dark brown
chert is present in those wells located in northern Florida and near
the plastic facies boundary. Milky and mammillary chalcedony and
fine quartz crystals are also present in the upper part of the for-
mation, commonly in cavities and vugs.
Thickness of the formation varies considerably from about 300
feet in northern Florida to about 900 feet in southern Florida (figs.
19-21).
AVON PARK LIMESTONE
Applin and Applin (1944) have named the Avon Park Limestone
to include the upper part of the late Middle Eocene which exhibits
its distinct faunal and lithologic characteristics in northern and
peninsular Florida. The formation as originally defined is primarily
a biostratigraphic unit underlying the Ocala Group (Upper Eocene)
and overlying the Applins' "nonfossiliferous limestone" which they
have considered to be equivalent to the Tallahassee Limestone.
However, during the course of investigation of well cuttings and
cores in this study, the writer recognized that there are distinct
lithologic differences between the Avon Park Limestone and the
strata lying above and below throughout northern and peninsular
Florida.
Generally, the top of the Avon Park is marked by the presence
of brown, finely fragmental and fossiliferous limestone or a brown
and fine crystalline dolomite bed, either of which is quite different
lithologically from the overlying strata of the Ocala Group and
can be easily identified from well samples. The base of the unit is
defined by the occurrence of relatively thick, nonfossiliferous, brown
to dark brown, and fine to medium crystalline dolomite bed over-
lying the Lake City Limestone which is generally marked at the
top by highly carbonaceous dolomite and limestone units (figs.
19-21). The formation is overlain unconformably by the Ocala
Group and younger strata, and it rests conformably on the Lake
City Limestone in northern and peninsular Florida, although local
unconformities may have existed.
Lithologically, the Avon Park is composed mainly of fossilifer-
ous limestone and dolomite with a very small amount of evaporite.
The limestone is light brown to brown, finely fragmental, rather
Porous, and highly fossiliferous (mostly foraminifers). The dolo-
mite is brown to dark brown, rather porous, very fine to medium
crystalline, and saccharoidal in texture. Fossil remains and molds






60 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

are commonly preserved in the dolomite. Evaporites, represented
essentially by gypsum, are present in small amounts, and are nie
with in only a few wells. Carbonaceous material is also present i
both limestone and dolomite.
Faunally, the Avon Park Limestone is characterized by the'
presence of abundant Coskinolina, Lituonella, Dictyoconus, and
many other diagnostic foraminifers. Other fossils such as astra.
codes, bryozoans, mollusks, and echinoids are also present, but are
rather rare and limited in areal distribution. Plant remains are alsod
present in the form of peat and carbonaceous material.
The Avon Park Limestone crops out on the crest of the Ocala'
Uplift in Levy and Citrus counties. In the subsurface, the formation
extends into southern Georgia, eastern panhandle Florida, and all
of northern and peninsular Florida except in Columbia, Suwannee,'
and Duval counties, where it is very thin or absent (figs. 19 and 21).
The thickness of the formation varies from zero to a few feet
in northern Florida to more than 800 feet in southern Florida (fig.'
19-21). It is demonstrable that thickness differences reflect both
depositional and tectonics and post-depositional erosion.
The Lake City Limestone and the Avon Park Limestone are
combined for analysis in order to use them in a joint lithofacies
study in panhandle Florida where the Claiborne Group is not differ-
entiated (figs. 33-35). Figure 33 is the isopach-lithofacies map of
the Claiborne Group in the entire Florida region. The regional
facies distribution of combined Lake City-Avon Park Limestone is
shown in figure 34. The dolomite concentration on the Peninsular
Arch and the limestone dominance in southern Florida and near the
plastic facies boundary in northern Florida are clearly shown. Areas
with relatively high evaporite content (fig. 36) are reduced really
and volumetically as compared with earlier units.
UNDIFFERENTIATED CLAIBORNE GROUP
The exposed strata of the Claiborne Group (Middle Eocene) in;
western Alabama have been divided into three formations; in
ascending order, the Tallahatta Formation, the Lisbon Formation,
and the Gosport Sand. These formations consist chiefly of deltaic
and marine plastics including green-gray shale; glauconitic sand-
stone; glauconitic, fossiliferous, and calcareous shale; cross-bedded,
fine- to coarse-grained sandstone; and carbonaceous shale. However,
in the subsurface farther downdip toward the Gulf, the sediments
of the group become more calcareous and less readily differentiated
into distinct formations (Toulmin, 1955).






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS 61



0000




.:;: .: . -. --. .- -











CLASTICS1 0
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DOLO / LS RATIO

FACIES BOUNDARY 1oo
002001




2 25 50 75 100 MILES




SHAN CHEN 1963 NORTHWESTERN UNIVERSITY
0 000T























Figure 33. Isopach-lithofacies map of the Claiborne Group (Claiborne Stage)
of Florida.
of Florida.










62 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


NONCLASTIC

FACES

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CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 34. Isopach-lithofacies map of the Claiborne Group (Claiborne Stage)
of peninsular Florida.


- 800

-1000


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REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


9400

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LHI SH AN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 35. Isopach-lithofacies map of the Claiborne Group (Claiborne Stage)

of panhandle Florida.









64 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


Figure 36. Evaporite percentage map of the Claiborne Stage of Florida.





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


In the western part of panhandle Florida, the Claiborne Group
has been divided into two formations, the Lisbon Formation at the
top and the Tallahatta Formation below, correlated with the Avon
park Limestone and the Lake City Limestone, respectively, of the
non-clastic facies in peninsular Florida (Puri and Vernon, 1959). As
has been stated previously, the writer makes no attempt to sub-
divide the Claiborne Group into formations in panhandle Florida,
and, therefore, the group is here treated as an undifferentiated
unit. The top of the undifferentiated Claiborne Group is marked by
the occurrence of rather highly glauconitic, arenaceous, and fos-
siliferous limestone, or brown, finely fragmental, argillaceous and
fossiliferous limestone, which unconformably underlies the Ocala
Group (Upper Eocene). The base is defined by the presence of
glauconitic and calcareous sandstone, or brown-gray and argillace-
ous limestone, or dark gray, glauconitic and arenaceous shale, which
conformably overlies the Wilcox Formation (figs. 21 and 22).
Lithologically, the undifferentiated Claiborne Group can gener-
ally be separated into two parts. The lower part of the group is
composed mainly of glauconitic and calcareous sandstone; green-
gray to dark gray, glauconitic, arenaceous and calcareous shale;
and glauconitic and arenaceous limestone; and brown-gray and
argillaceous limestone (figs. 21-22). Minor amounts of green-gray
and siliceous shale and glauconitic siliceous limestone are also
encountered in certain wells. The glauconitic sandstone grades
southeasterly into glauconitic and argillaceous limestone; farther
southeast, across the facies boundary, it is replaced entirely by
nonclastic sediments, while southwesterly toward the Gulf, the sand-
stone is gradually replaced by glauconitic and calcareous shale and
glauconitic, argillaceous and arenaceous limestone. The upper part
of the group consists essentially of glauconitic, arenaceous, and
fossiliferous limestone and minor beds of glauconitic and calcareous
shale.
The thickness of the undifferentiated Claiborne Group varies
from less than 400 feet around the Chattahoochee Arch to more
than 800 feet near the Gulf.
Both vertical and lateral lithologic changes of the undifferenti-
ated Claiborne Group in panhandle Florida are shown on the strati-
graphic cross section, C-C' and D-D' (figs. 21-22). Regionally, the
major lithologic changes of the group in the panhandle are shown
on the isopach-lithofacies maps (figs. 33 and 35). The maps show
that sediments with a high content of coarse clastics are present
around the area of the Chattahoochee Arch, and that limestone con-


65






66 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

tent increases toward the eastern panhandle and the peninsula.
Both argillaceous and calcareous sediments become dominant south-
westward near the Gulf.
The more important geological information which can be direct-
ly interpreted from the joint study of the isopach-lithofacies maps
(figs. 33-35) and the structure map (fig. 11) of the Claiborne Group
in Florida is summarized as follows:
1. Clastic sediments increase steadily northward from pan-
handle Florida to southern Alabama and Georgia, while the
nonclastics become dominant southward near the Gulf and
southeastward in the eastern panhandle and the peninsula
where clastics are almost completely absent.
2. Dolomite is dominant on the Peninsular Arch region. Away
from the arch, limestone becomes a principal lithology.
3. Clastic-nonclastic faces boundary is shifted farther north-
west toward the panhandle as compared with older units.
4. Evaporites are greatly reduced, both volumetrically and
really, in comparison with older units.
5. Facies and isopach strikes are almost parallel to each other
in the panhandle, but are rather discordant in the peninsula.
6. Regionally, structure and isopach strikes parallel each other
quite closely.

OCALA GROUP
PRE-JACKSONIAN (SUB-OCALA) UNCONFORMITY
Late Middle Eocene state are unconformably overlain by the
Ocala Group (Upper Eocene). The unconformity is evidenced by:
(1) progressive thinning of the Avon Park Limestone (Late Middle
Eocene) toward the Peninsular Arch with truncation below the
Ocala in certain areas on the crest of the arch; (2) superposition
of Ocala on the lower part of the Avon Park Limestone and on
early Middle Eocene units in certain areas in panhandle and penin-
sular Florida; (3) marked biostratigraphic hiatus; and (4) appar-
ent compaction, diagenesis, and lithification of the Avon Park strata
before deposition of the poorly consolidated Ocala limestones.
JACKSON STAGE
The Jackson Stage (Upper Eocene) in western Alabama out-
crops has been subdivided into two formations, the Moodys Branch
Formation below and the Yazoo Clay above. These two formations
are composed essentially of marine and deltaic plastic sediments.






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


The Moodys Branch consists chiefly of calcareous and glauconitic
sandstone, and the Yazoo Clay is dominated by green-gray, cal-
careous and poorly consolidated shale and calcareous sandstone
(Toulmin, 1955). Both formations can be traced eastward and
southward in the subsurface; however, they gradually become much
more calcareous and rather similar in lithology and finally grade
into the Ocala Limestone in eastern and southern Alabama. The
term Ocala Limestone which was originally introduced by Dall and
Harris (1892) has been widely used by many Coastal Plain geolo-
gists to cover all the calcareous sediments of Upper Eocene age in
southern Alabama, southern and western Georgia, and Florida. Puri
(1957) has made a detailed historical review of usage of the term
Ocala Limestone.
The Upper Eocene strata in Florida which were formerly in-
cluded in the Ocala Limestone have been separated by Puri (1957),
on the basis of a detailed biostratigraphic study, into three forma-
tions of the Ocala Group, namely, the Inglis, the Williston, and the
Crystal River in ascending order.
In northern and peninsular Florida, the top of the Ocala Group
is generally marked by a chalky white to very light brown, poorly
consolidated, fragmental, microcoquina-like and highly fossiliferous
limestone bed composed almost entirely of foraminifers and minor
amounts of other fossils; however, in panhandle Florida, the top is
defined by a light brown, slightly glauconitic and arenaceous, frag-
mental and fossiliferous limestone bed. The base of the group is
commonly defined by a brown to dark brown, rather soft, saccha-
roidal textured, and fine crystalline dolomite, or a light brown to
brown, finely fragmental and fossiliferous limestone, or a slightly
arenaceous and fossiliferous limestone (figs. 19-22).
The Ocala Group is overlain unconformably by the strata of
Oligocene and post-Oligocene age, and it overlies unconformably
the Avon Park Limestone (Late Middle Eocene). The vertical and
lateral lithologic changes as well as the regional lithofacies distri-
bution of the group are well illustrated on the stratigraphic cross
sections (figs. 19-22) and the isopach-lithofacies map (fig. 37).
Generally, in northern and peninsular Florida at least, the Ocala
can be separated lithologically into an upper and a lower part. How-
ever, the writer has made no attempt to divide the group into
formations for the purposes of the present study.
The Ocala Group crops out only around the Chattahoochee Arch
and the Ocala Uplift and elsewhere is covered by post-Eocene sedi-
ments (fig. 1). In the northern part of western panhandle Florida,








68 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


, 0-
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CONTOUR INTERVAL: 100


0 25 50 75 100 MILES

0 50 100 KILOMETERS
6I Im


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CHEN 1963 NORTHWESTERN UNIVERSITY


Isopach-lithofacies map of the Ocala Group (Jackson Stage) of
Florida.


CHIH SHAN


Figure 37.






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


the group is composed mainly of fossiliferous, glauconitic and
arenaceous limestone with minor amount of dolomite and calcareous
shale. This lithologic assemblage grades eastward in the peninsula
and southward toward the Gulf into a highly fossiliferous limestone
dominated by large foraminifers. In peninsular Florida, the group
consists essentially of highly fossiliferous limestone with only a
minor amount of dolomite at the base. The limestone is chalky
white to very light brown, porous and not well consolidated, finely
fragmental to microcoquinoid. Reef-like limestone beds have been
encountered in the well (W-1500, Baker County) located in north-
ern Florida. Generally, the fossils and fossil fragments are loosely
cemented by a sparry calcite matrix. Faunally, the group is char-
acterized by the presence of abundant large foraminifers such as
Lepidocyclina, Nummulites, and Operculinoides; megafossils such
as echinoids and bryozoans are relatively rare.
The Ocala Group is absent in several areas as shown in figure
37. This condition may be caused partly by post-depositional erosion
and partly by nondeposition. The thickness of the group varies con-
siderably from less than 100 feet in the northern panhandle and
the central peninsula to more than 400 feet in southern Florida and
near the Gulf in the panhandle. The irregularity of the isopach
pattern (fig. 37) is mainly due to post-depositional erosion.
The regional distribution of the major lithologies of the Ocala
Group in Florida is represented in figure 37. Although the regional
facies pattern does not fully represent the original picture of the
group, the writer believes that it is very helpful in making any
geological interpretation in terms of the depositional environments
and regional tectonics. The following geologic information can be
obtained from the study of the isopach-lithofacies map (fig. 37)
and the structure map (fig. 12).
1. Limestone is a dominant lithology of the Ocala Group
throughout the area studied.
2. The clastic-nonclastic facies boundary is shifted even farther
west toward the panhandle than is evidenced by earlier units.
3. Dolomite is a minor lithologic component in comparison with
underlying units and is distributed in rather limited and
isolated areas which show no connections with either the
isopach pattern or the regional tectonic elements.
4. The area with relatively high content of plastic sediments
is in the western panhandle, particularly on the Chattahoo-
chee Arch.






70 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

5. Facies and isopach strikes are generally discordant, except
in the western panhandle where they are more or less
parallel.
6. Structure and isopach strikes approach parallelism only in
the western panhandle and southern Florida.
7. The Ocala Uplift and the Peninsular Arch are obvious on
the structure map, but very little evidence of the influence
of these features is seen on the isopach-lithofacies map.

SUMMARY OF EOCENE SERIES
The entire Eocene Series is also analyzed lithostratigraphically
in terms of its regional lithologic distribution and the results are
shown on a series of maps (figs. 38-40).
Figure 38 is the isopach-lithofacies map of Eocene Series in
the Florida region. The map shows that the regional facies pattern
is only slightly different from those shown in figures 39 and 40, the
separate treatments of the plastic and nonclastic facies areas.
Thickness of the series varies rather considerably from less than
1400 feet to more than 2800 feet in peninsular Florida and from
less than 1000 feet to more than 2000 feet in panhandle Florida.
In northern and peninsular Florida, the Eocene Series is com-
posed essentially of dolomite and limestone with a minor amount of
evaporites (gypsum and anhydrite). The regional distribution of
these three lithologies are shown in figure 39. Dolomite is dominant
on the Peninsular Arch region, while limestone becomes a major
lithology in such areas as northern and southern Florida. Evapo-
rites are developed only in rather limited areas as outlined by the
carbonate-evaporite ratio lines.
Figure 40 shows the regional lithologic distribution of the clas-
tic facies in panhandle Florida. It indicates clearly that coarse
plastic sediments are dominant around the Chattahoochee Arch,
and finer clastics and more calcareous sediments become important
southwesterly toward the Gulf; plastic sediments are almost com-
pletely replaced by nonclastics in the peninsula.
The regional lithofacies distribution of the series as shown on
those maps (figs. 38-40) presents the following noteworthy geologic
information:
1. The Peninsular Arch is well shown by the isopach pattern,
while the Chattahoochee Arch is less distinct.
2. South Florida Basin is shifted slightly northeastward to the
Lake Okeechobee region from its position in Paleocene time.








REGIONAL LITHOSTRATIGRAPHIC ANALYSIS 71




0 0 0 00


















4i







DOL
DOL0 I I I a .. llllimllll 322 LS









(4 EVAP) 2 I
.:. :-











4 NONCLASTIC CLAST IC RATIO














FACES BOUNDARY
S(SS 00 KILOMETERS+SH)
i'i 7




























CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 38. Isopach-lithofacies map of the Eocene Series of Florida.
Figure 38. Isopach-lithofacies, map of the Eocene Series of Florida.







72 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


NONCLASTIC
FACES


,0


/7


EVAP


8 2 I
2
DOLO /LS RATIO


-- 8-- CARBONATE/EVAPORITE RATIO

DOLO LS RATIO
-I-I-I--I- I- FACES BOUNDARY


CONTOUR INTERVAL: 200


0 25 50 75 100 MILES
0 50 100 KILOMETERS


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY

Figure 39. Isopach-lithofacies map of the Eocene Series of peninsular Florida.


DOLO









REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


NONCLASTICS




110
4 .







4


SS SH


SS /SH RATIO



4 PLASTIC NONCLASTIC RATIO

SS/SH RATIO

-I-I-I- --- FACES BOUNDARY


CONTOUR INTERVAL: 200


0 25 50 75 100 MILES

0 50 100 KILOMETERS
I I I'


CHIH SHAN CHEN 1963 NORTHWESTERN UNIVERSITY


Figure 40. Isopach-lithofacies map of the Eocene Series of panhandle Florida.


73


S *0*0


. *
*

*
0


0

*


S
0 0
0


*


0


*.


0
*a






74 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

3. The Suwannee Channel is probably marked by the faces
boundary and the saddle-like form outlined by the 2000 foot
isopach line.
i. Facies and isopach strikes are generally parallel.
INTERPRETATIVE STRATIGRAPHY
GENERAL CONSIDERATION
Integration of isopach-lithofacies maps and structure maps with
petrographic and paleontologic data makes possible more reliable
interpretations of petrogenesis (including provenance, distribution,
depositional environment, and diagenesis) and of the regional tec-
tonics of Paleocene and Eocene time in Florida. Two distinct sedi-
mentary facies, plastic and nonclastic, have been recognized and
differentiated on a series of isopach-lithofacies maps of the suc-
cessive stratigraphic units. Although these two facies are closely
related in space and time, they should be considered separately in
terms of their sedimentary parameters.
The plastic sediments which dominate panhandle Florida and
the northern and western Gulf Coast region not only bear evidences
of their predepositional history, but in addition have also recorded
some of the characteristic imprints of depositional and diagenetic
processes. Textural and mineralogic investigations, therefore, are
the major means of determining source-rock types, processes of
weathering at the source area, duration of transportation, char-
acteristics of the depositional environment, state of tectonism, and
processes of diagenesis. On the other hand, the nonclastic sedi-
ments, the dominant lithologies in peninsular Florida, reveal only
the characteristics of the depositional environment, the processes
of diagenesis, and the influence of major tectonic elements.
Evaporites represent chemical processes alone, while carbonates
are generally considered to be both chemical and biochemical prod-
ucts. Therefore, such information as (1) the content of major (Ca
and Mg) and trace (Rb, Sr, and others) elements, (2) the abun-
dance of stable isotopes (C12 and C13, 016 and 018, and S32 and S34),
and (3) the type and content of fossils and their regional distribu-
tion, becomes even more significant, geologically and geochemi-
cally, in respect to the interpretation of physical, chemical, and
biological conditions of the depositional environment, the diagenetic
processes, and the regional tectonic controls.
The writer believes that the concept of uniformitariansim is
applicable to the interpretations of depositional environment of






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


Early Tertiary rocks in Florida in terms of physical, chemical, and
biological conditions. The following reconstruction is based primari-
ly on the major lithologic types, their regional distribution, and
the paleontologic assemblages which they contain. These are evalu-
ated in terms of local and regional depositional environments and
in the light of the tectonic framework of the Paleocene and Eocene
rocks in Florida.
REGIONAL TECTONICS AND DEPOSITIONAL
ENVIRONMENTS
LITHOLOGIC CHARACTERISTICS
Nonclastic sediments-carbonates and evaporites are the major
lithologies of the nonclastic facies in peninsular Florida.
Limestone and dolomite are generally pure and clean as shown
by insoluble residue analysis. Only a trace amount of organic and
argillaceous materials has been found in certain grayish and more
or less impure limestone and dolomite.
Fossiliferous limestones are very common, and some of these
are microcoquinoid and consist almost entirely of foraminifers and
other microorganisms. Macrofossils are generally rare, but they
may be quite abundant in certain stratigraphic intervals encount-
ered in some wells in northern Florida.
Reef-like limestone ranging in age from Lower Eocene to Upper
Eocene have been encountered in some wells in northern Florida
(W-890, Nassau; W-1500, Baker; W-1596, Madison; and W-2775,
Suwannee). Major reef trends have never been recognized in well
samples and electric logs of the Paleocene and Eocene sections in the
area studied. However, the writer is convinced that a corollary of
the distribution pattern of modern marine carbonates, such as in
the Bahamas and Florida Bay and Keys could exist in the Early
Tertiary of Florida. It seems possible that reef masses could be
found in the Paleocene and Eocene sections of such regions as the
continental shelf on the east side of peninsular Florida, the Ba-
hamas, and the southernmost part of the Florida Platform. These
are the areas facing prevailing ocean current directions.
Highly carbonaceous carbonate beds which are commonly inter-
bedded with laminae or thin beds of peat are found in the upper-
most part of the Lake City Limestone (early Middle Eocene) with
a rather wide regional distribution in northern and central penin-
sular Florida (fig. 32). This evidence again suggests that, near the
end of deposition of the Lake City, northern and central peninsular
Florida was probably an area of very shallow, warm, and more or






76 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

less lagoonal environment enclosed by the broad carbonate bank
occupying all of peninsular Florida. Here, seaweeds and other
marine plants flourished together with other marine organisms so
as to produce the highly carbonaceous carbonate and thin peat beds.
Paleocene-Eocene dolomites are brown to very dark brown,
microcrystalline to coarse crystalline, and rather porous. Microcrys-
talline dolomite is predominant in the Paleocene strata; fine to
coarse crystalline dolomite is characteristic of Lower and Middle
Eocene strata; while limestone becomes a principal lithology in
Upper Eocene strata. Generally, the regional lithofacies patterns
illustrate that the dolomites are more common on the structural
highs than on the structural lows. Except for complications intro-
duced by dolomitization on structural highs the carbonates are
quite uniform in terms of their gross lithologic characteristics on
a regional scale.
Williams and Barghoorn (1963), on the basis of study of dis-
tribution of recent marine carbonates in the "American Mediter-
ranean" region, concluded that:
In summary, it appears that biological phenomena or biologi-
cal processes are the principal cause, directly or indirectly,
of carbonate precipitation in the oceans and that the sites of
precipitation bear recognizable, though complex, relation-
ships to ocean currents and to physiographic features of the
ocean basins.
From the study of regional distribution of recent marine car-
bonate sediments in the world as a whole (excluding the deep sea
oozes), one finds that organic reef complexes and continental shelf
carbonates are confined within a narrow belt between the latitudes
of 30 north and 30 south. Biologically, the necessary conditions
for the support of life in the oceans, and thus for the precipitation
of marine carbonates, are (1) relatively intense illumination within
the euphotic zone, (2) warm water temperature (210-320C or 70-
900F), and (3) sufficient supply of inorganic nutrients. These three
major requirements can only be met in such environments as warm
and shallow water marine conditions on relatively flat and broad
shelves, banks, and platforms. The present-day Bahamas and the
Compeche Bank could be taken as models for making interpreta-
tions of the environmental conditions under which the Paleocene
and Eocene carbonate rocks were formed on the Florida Platform.
Anhydrite, gypsum, and inorganically precipitated carbonates
are the only evaporite minerals found in the Paleocene and Eocene
strata in Florida. Vertical repetitions of cyclical deposition of car-
bonates and evaporites is a common phenomenon in the lower part






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


of the Paleocene section, particularly in the western part of central
peninsular Florida and in southern Florida. Laterally, evaporite
beds are replaced by carbonates.
Theoretically, in order to produce a 1-foot bed of anhydrite it is
necessary to evaporate a 1400-foot column of sea water of normal
composition. Therefore, it is quite clear that in order to obtain tens
of hundreds of feet of evaporite beds over a large area as in the
Paleocene strata in Florida, it requires a depositional environment,
such as the silled reflux basin envisaged by King (1947), Scruton
(1953), and Briggs (1958).
The evaporite basins are outlined on the evaporite percentage
maps (figs. 27 and 31) and on the isopach-lithofacies maps (figs.
24-25, and 28-29). These evaporite basins were well developed dur-
ing Early Paleocene time; however, they were greatly reduced dur-
ing Late Paleocene and Lower Eocene time, and were almost
completely absent during late Middle Eocene and Upper Eocene
time.
As has been mentioned previously, large reef masses or reef
trends have never been encountered in the Paleocene and Eocene
sections in peninsular Florida. In the absence of reef trends as
restricting sills, the evaporite lagoons developed in the peninsular
Florida region during Paleocene and early Lower Eocene time could
have been surrounded by relatively broad (probably tens of miles
wide) but very shallow (water depth probably around 10 feet)
carbonate banks with a few channels cutting through them. These
banks could serve as sills to restrict the evaporating body of water
within the shallow lagoon so that free circulation could not take
place and the concentration of the brine gradually increased.
Clastic sediments.-The plastic sediments of the Paleocene and
Eocene strata in panhandle Florida as well as in western and south-
ern Alabama and southern Georgia are composed essentially of
poorly consolidated, carbonaceous, calcareous, and glauconitic sand-
stones; green-gray to gray-black, laminated, micaceous, glauconitic,
and calcareous shales; and nonfossiliferous to fossiliferous, glau-
conitic, arenaceous, and argillaceous limestones. Carbonaceous mate-
rial and coarser clastics (sand and silt) become dominant northward
toward the outcrop belt.
X-ray analyses of calcareous shales of various Paleocene and
Eocene stratigraphic units in panhandle Florida indicate that mont-
morillonite and illite are the principal clay minerals with kaolinite
in minor amounts, and that montmorillonite is more common than
illite. Generally, the regional clay mineral distribution pattern as






78 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

represented by limited number of samples analyzed in this study
indicates that the amount of montmorillonite increases southwest-
ward toward the Gulf. This evidence probably suggests that these
shales were deposited in shallow marine environment as they are
formed today in the shelf region of northeastern Gulf Coast (Grif-
fin, 1962).
The regional lithofacies patterns of successive stratigraphic
units studied are shown on the series of maps in the preceding
chapter. The patterns indicate clearly that the coarser clastics are
dominant on the structural highs, such as the Chattahoochee Arch,
in panhandle Florida and northward toward the Piedmont region,
while finer clastics and carbonates become the major lithologic com-
ponents southward toward the Gulf and southeastward toward
peninsular Florida. The writer, on the basis of lithologic character-
istics of these Paleocene and Eocene strata, believes that those
plastic sediments found in panhandle Florida are related to the
continental shelf region with marginal marine conditions, while
the rocks seen at and near the outcrop belt adjacent to the Pied-
mont area are believed to have been deposited in environments
ranging from transitional (or deltaic) to continental.
The source area of the plastic sediments in panhandle Florida
and other parts of the southeastern Coastal Plain during Paleocene
and Eocene time was most likely the Southern Appalachians. The
fact that the amount of plastic sediments is greatly reduced near
southern Georgia and northern panhandle Florida and that clastics
are completely absent in peninsular Florida leads to consideration
of the following interpretations: (1) the pattern could be due to
the existence of a natural barrier between these two sedimentary
facies, (2) no large streams were available for transporting a large
amount of plastic sediments into the depositional site, and (3) only
a small amount of clastics were actually contributed from the
source area.
The writer believes that the presence of a natural barrier, that
is, the Suwannee Channel, may be the major factor in separating
these two distinct sedimentary facies. However, it remains possible
that all of these three factors could well be equally important and
could have operated jointly throughout the entire Paleocene and
Eocene time.
PALEONTOLOGICAL CHARACTERISTICS
Organisms respond to and record the whole complex of environ-
mental conditions under which they live as do the sediments with







REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


which they are associated. Therefore, one would expect that there
should be two quite different faunal assemblages representing the
two distinct sedimentary environments, plastic and nonclastic, in
panhandle and peninsular Florida, respectively, during Early Terti-
ary time.
Applin and Applin (1944), on the basis of detailed study of
microfaunas, especially the foraminifers, of the Cretaceous and
Tertiary strata in Florida and southern Georgia, have made the
following statement:
In general also, the foraminiferal microfaunas of the plastic
facies resemble those present in formations in the western
Gulf Coast, whereas the microfaunas of the limestone facies
in the peninsula from the top of the early Middle Eocene to
the top of the beds of Taylor age resemble those of Cuba,
the West Indies, Mexico, and Europe, with only few species
present that are known in other places in the United States.
Cheetham (1963) has made an extensive study of the abundance
and distribution of cheilostome bryozoan associations, and the
nature of other fossils, and of the sediments of the Jackson Stage
(Upper Eocene) in southern Alabama, southern Georgia, and pan-
handle and peninsular Florida. By categorizing individual cheilo-
stome faunules as associations and considering these in terms of
known ecological requirements and tolerances of living cheilostomes,
he has been able to identify three different depositional environ-
ments, namely, (1) shelf phase, from the Mississippi-Alabama
border to the Alabama-Georgia-Florida corner, (2) bank phase,
peninsular Florida, and (3) barrier between shelf and bank, the
zone of Suwannee Channel, in which different assemblages lived
and different sediments accumulated during Upper Eocene time.
Nonclastic facies (peninsular Florida region).-The vast num-
ber of foraminifers presented in the carbonate rocks of Paleocene
and Eocene sections in peninsular Florida are mostly referable to
such families as Valvulinidae (including genera of Lituonella,
Coskinolina, Dictyoconus, and Gunteria), Miliolidae, Alveolinel-
lidae( Borelis), Amphisteginidae (Asterigerina, Helicostegina, and
Amphistegina), Orbitoididae (Lepidocyclina, Orbitoides, Lepidoor-
bitoides), and Nummulitidae (Nummulites, Camerina, and Operi-
culinoides). Paleoecologically, almost all of these foraminifers are
characteristic of shallow (less than 100 feet in water depth), warm
(tropic to subtropic) waters where they are commonly associated
with calcareous algae of the photic zone (Cushman, 1948). Accord-
ing to Johnson (1961) most calcareous algae live in strong light at,
or very close to, low-tide level, and at least half of them are re-






80 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

stricted to water depths of less than 60 to 75 feet. Large foramini-
fers common in the successive stratigraphic units studied, especially
in the Ocala Group, are known to occur in a stenotopic tropical
environment, living in a water depth range of 125 to 200 feet, and
in calcareous mud, on biostromes and bioherms (Puri, 1957).
According to Cheetham (1963) the Jacksonian (Upper Eocene)
carbonate rocks of peninsular Florida accumulated on a carbonate
bank. He has suggested that the water depth probably did not ex-
ceed 150 feet over the most part of peninsular Florida at any time
during the Jacksonian, and that the depositional environment seems
to have been a lagoon with shoal-water, tropical climate, and excep-
tionally uniform hydrographical conditions.
As has been discussed previously, the lithologic evidences of
the Paleocene and Eocene rocks in peninsular Florida fully support
these authors' interpretations regarding the physical, chemical,
and biological conditions of the depositional environment.
Clastic faces (panhandle Florida region).-According to Applin
and Applin (1944) foraminifers of strata ranging in age from
Paleocene to early Middle Eocene in panhandle Florida are not only
strikingly different from those common throughout peninsular
Florida, but also are rare. Such faunal changes are in harmony
with the regional lithofacies patterns, that is, the Paleocene and
Early Eocene carbonate rocks of the peninsula are clearly differ-
entiated from the plastics of the panhandle. However, such marked
faunal and lithologic differences gradually become obscure in the
late Middle Eocene and Upper Eocene rocks of the same areas,
reflecting the northward and northwestward spread of nonclastics
over the panhandle during the time from late Middle Eocene to
Upper Eocene.
Cheetham (1963) has pointed out that the Upper Eocene sedi-
ments of panhandle Florida and southern Alabama were deposited
on the continental shelf in water 100-300 feet deep. In early Upper
Eocene time the terrigenous sediments were abundant, and they
spread southeastward nearly to the edge of the shelf. However,
with the passage of time, the detrital material was gradually re-
duced both in its quantity and in its areal extent. Cheetham also
has stated that the chief evidence of the Suwannee Channel bar-
rier is indicated by the presence of lagenid and buliminid foramini-
fers and by the absence of bryozoans.
Gardner (1957) has made a paleoecologic study of the faunas
(dominantly molluscan) of an Early Tertiary section cropping out
on Little Stave Creek, Alabama. She concluded that the entire






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


sequence of Eocene and Oligocene sediments was probably laid
down on a shifting continental shelf beyond the intertidal zone;
that average water depth may have been about 240 feet or less;
and that water temperature during the Eocene was probably as
high or higher than it is in the northern Gulf of Mexico today.

TECTONO-ENVIRONMENTAL CONDITIONS AND
SEDIMENTATION
The lithologic and paleontologic interpretations of inferred eco-
logical and environmental conditions make possible the reconstruc-
tion of the regional pattern and relationships between tectonic
elements and sedimentary environments under which these Paleo-
cene and Eocene rocks were formed.
NONCLASTIC FACIES (PENINSULAR FLORIDA REGION)
Two major structural elements, the Peninsular Arch and the
South Florida Basin (fig. 2), played the major role in controlling
the distribution of sedimentary environments which, in turn, con-
trolled the detailed patterns of sediment distribution during Paleo-
cene and Eocene time. As has been pointed out, the Peninsular
Arch forms the backbone of the broad Florida Platform throughout
the entire geological time interval from Paleozoic to Recent. The
South Florida Basin was a regionally downwarped area where rela-
tively thiek accumulation of nonclastic sediments of Paleocene and
Eocene age (more than 4000 feet) were deposited under slowly but
steadily subsiding condition. These two structural elements are
demonstrable on the series of isopach-lithofacies maps, structure
maps, and evaporite percentage maps presented in the preceding
chapters.
geophysical and geologic data suggest that the tectonic belts
of both the Southern Appalachian and the Ouachita systems may
join together underneath the Florida Platform (Drake and others,
1963; E. R. King, 1959). However, local magnetic anomalies on the
West Florida Escarpment indicate no linear belt, at least in the
area surveyed, but probably represent buried volcanic cones that
provided the sites upon which the calcareous banks formed (Miller
and Ewing, 1956).
Petrologic and paleontologic evidences, such as (1) the exclu-
sively nonclastic nature of the sediments, (2) generally fossilifer-
ous to highly fossiliferous character of limestones, (3) cyclical
deposition as well as vertical repetition of carbonates and evapor-
ites, (4) high degree of purity and lithologic uniformity of car-






82 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

bonate rocks, and (5) their inferred ecologic and environmental
conditions lead the writer to interpret these nonclastic sediments
as deposits on a stable carbonate bank or shelf in warm, shallow
water, and open marine environment. The writer believes, in gen-
eral, that similar sedimentary-environmental conditions to those
existing today in the Florida Bay and Keys, the Great Bahamas,
and Campeche Bank could be taken as models for interpretations
of the environmental conditions under which the nonclastic sedi-
ments were deposited on the Florida Platform during Paleocene
and Eocene time.
In this view, at the beginning of Paleocene time, the broad
region of the Florida Platform was a stable carbonate bank bounded
by submarine escarpments on both the Atlantic and the Gulf of
Mexico sides and separated from the continental shelf at the north
by the Suwannee Channel. The platform probably included a broad
bank in its northern and central portion and a broad lagoon in its
southern portion, both characterized by shallow water, warm cli-
mate, relatively uniform hydrographic conditions, and open marine
environment. Scattered reef masses were present on the bank,
probably along its northern and eastern margins.
The entire Florida Platform was submerged during Paleocene
and Eocene time, except in the late Middle Eocene and late Upper
Eocene time when the greater part of the northern and central
portions of the platform was emergent and subjected to nondeposi-
tion and subaerial erosion. This emergence is evidenced by the
unconformable relationships between the Ocala Group (Upper Eo-
cene) and the beds lying above and below. Sedimentation was
probably continuous throughout Early Tertiary time in the south-
ern part of the platform where evaporitic restriction of lagoonal
environments was relaxed near the end of Early Eocene time as
shown by the reduction of evaporites both in quantity and in areal
extent.
No severe crustal movements affected the entire Florida Plat-
form and southeastern Coastal Plain during Early Tertiary time.
It is believed that the Peninsular Arch and South Florida Basin
have been modified only by a series of epeirogenic movements of
differential downwarping of the embayments or basins and slower
subsidence of marginal areas and arches.

THE SUWANNEE CHANNEL
The Suwannee Channel (fig. 2) was the site of relatively thin
accumulation of very fine sands, silts, clays and limestones at least






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


during the time from late Upper Cretaceous to Lower Eocene (figs.
5, 6, and 21). The channel was a natural barrier and facies boun-
dary, both sedimentational and biologic, between two distinct sedi-
mentary facies in the area throughout the entire Early Tertiary
time. North and northwest of the channel is the plastic facies com-
posed of sandstone, shale, and limestone, while just south of the
channel is the nonclastic facies consisting almost exclusively of
carbonates and evaporites.
As has been briefly mentioned previously, the presence of the
Suwannee Channel during late Upper Cretaceous and Early Terti-
ary time is indicated by the following interpretations.
1. Paleoecology.-According to Moore (1955) and Cheetham
(1963), shallow-water types of larger foraminifers and cheilostome
bryozoan assemblages are very common in Upper Eocene sediments
in peninsular Florida and on the shelf region northward near the
Piedmont. However, these shallow-water faunas are rare or absent
in sediments of the same age at the position of the Suwannee
Channel. Here, deeper-water types of lagenid and bulminid fora-
minifers become dominant. In addition, although no reef belt has
ever been identified or reported in the literature, reef-like limestone
beds ranging in age from Lower Eocene to Upper Eocene have been
encountered in several wells located in those counties (Baker, Madi-
son, Nassau, and Suwannee) near the northern edge of the Florida
Platform. This may suggest that the platform could have been
bounded on its northern edge by a rather abrupt escarpment.
2. Petrology.-The Paleocene and Lower Eocene strata en-
countered along the channel are composed mainly of calcareous
shale in contrast to the coarser terrigenous clastics to the north
and northwest and pure carbonates and evaporites to the southeast.
3. Tectonics.-The lesser thickness of strata ranging in age
from late Upper Cretaceous to Lower Eocene within the channel
(figs. 5, 6, and 21) might be interpreted as due to either erosion
on a positive lineament or slower sedimentation within the channel.
Cenozoic structure of the channel is synclinal, and the thickness of
post-Lower Eocene rocks within the channel site is greater (1500
feet or more) than that on the Peninsular and Chattahoochee
arches (1000 feet or less) giving no evidence of Cenozoic positive
habit. Thus, the evidence strongly indicates slower Paleocene-
Eocene accumulation within the channel rather than differential
erosion.
These interpretations combine to suggest that the Suwannee
Channel was a bathymetric depression and a natural barrier, both






84 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

sedimentational and ecologic, during late Cretaceous and Early
Tertiary time.
By Middle or Upper Eocene time the Suwannee Channel was
probably no longer an effective natural barrier in separating the
plastic facies from the nonclastic facies. Disappearance of the
Suwannee Channel during Middle or Upper Eocene time may be
partly due to the continued transgression of the sea through Paleo-
cene and Eocene time as is demonstrated by the steadily shifting
facies boundary northward and northwestward from late Upper
Cretaceous to Upper Eocene time. Or, the reduced influence of the
channel may be due to great reduction of the amount of terrigen-
ous material contributed from the Southern Appalachian region to
the depositional site. Lastly, disappearance of the channel may
partly reflect a dramatic change in the drainage systems with
major streams flowing westward toward the Mississippi Embay-
ment and the Gulf, and eastward toward the Atlantic Coast. These
are the possibilities which must be considered in explaining the
encroachment of the nonclastic facies northward and northwest-
ward over the plastic facies.
CLASTIC FACIES (PANHANDLE FLORIDA AND ITS ADJACENT
AREAS)
In the Coastal Plain of southern Alabama, southern Georgia,
and panhandle Florida, the major pre-Cenozoic tectonic elements
are: (1) the northern "root element" of the Peninsular Arch,
which may better be considered as a part of the Southern Appala-
chian system, extended southward toward northern Florida, (2)
the Chattahoochee Arch, and (3) the Southeast Georgia and Apala-
chicola embayments. These tectonic elements are undoubtedly to
be considered as the "relics" of older structural elements, possibly
Paleozoic in age. These old features are covered with a considerable
thickness of Cretaceous and possibly older Mesozoic plastic sedi-
ments. It is believed that the latest Upper Cretaceous or early
Lower Paleocene widespread uplift that occurred in the southeast-
ern Coastal Plain resulted in the erosion of some Upper Cretaceous
beds over a broad area in Alabama, Georgia, and Florida and in the
formation of the structural sag occupied by the Suwannee Channel.
Following this uplift the entire southeastern Coastal Plain slowly
subsided and the sedimentation of Cenozoic sediments began.
At the beginning of Paleocene time, the southeastern Coastal
Plain region was a relatively unstable continental shelf separated
from the Florida Platform by the Suwannee Channel on its south-
eastern margin. The shelf was chiefly a deltaic or transitional and





REGIONAL LITHOSTRATIGRAPHIC ANALYSIS


shallow water marine environments receiving mainly sands, shales,
and limestones. A degree of interfingering between the plastic and
nonclastic facies must exist somewhere along the Suwannee Chan-
nel, although this can not be verified by the limited well data
available in this study. Therefore, a considerable amount of subsur-
face geologic information needs to be obtained before any reliable
interpretation can be made concerning the detailed stratigraphic
relationships between these two distinct sedimentary faces.
Several minor disconformities have been recognized in the Paleo-
cene and Eocene sections at the outcrop area, but they are generally
not recognizable in the subsurface in panhandle Florida, except at
the contacts of the Ocala Group (Upper Eocene) which show un-
conformable relationships with beds lying above and below.
Geologic and geophysical data indicate that the core of the
Chattahoochee Arch as well as the entire southeastern Coastal
Plain is composed of rigid rock masses of plutonic, metamorphic,
and weakly metamorphosed sedimentary rocks ranging in age from
Precambrian to Paleozoic. During Paleocene and Eocene time, the
shelf region in panhandle Florida, although relatively unstable, was
subject to a slow rate of subsidence with total accumulation of
sediments ranging from less than 1500 feet on the Chattahoochee
Arch to more than 3000 feet southwestward toward the Gulf. This
is in contrast to the western Gulf region where the sediments of
the entire Paleocene and Eocene sections reach a total thickness
ranging from about 5000 feet in southeastern Louisiana to more
than 20,000 feet in the Rio Grande Embayment of South Texas
(Hardin, 1962; Murray, 1961).
During Early Tertiary time, the rate of sedimentation in pan-
handle Florida as well as other parts of the Gulf Coast region was
never uniform. Murray (1951) has called loci or trends of greater
accumulation of sediments "depocenters" or "depoaxes", however,
neither panhandle nor peninsular Florida were significant "depocen-
ters" or "depoaxes" in Early Tertiary time.

PALEOGEOGRAPHY

The series of isopach-lithofacies maps, structure maps, and
lithologic cross sections of the Paleocene and Eocene Series in
Florida, together with lithologic and paleontologic data and ecologic
and environmental conditions inferred in this study are here inte-
grated to produce a series of paleogeographic maps of the succes-
sive stratigraphic units studied (figs. 41-44). The classification of






86 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE

the sea floor into different environments is according to bathymetric
zones of Hedgpeth (1957b) :
1. supralittoral (above high tide level),
2. littoral or intertidal (between tide levels),
3. inner sublittoral (low tide level to 150 feet or 50 meters),
4. outer sublittoral (between 150 and 600 feet or 50 to 180
meters),
5. bathyal (between 600 and 3300 feet or 180 and 1000 meters),
6. abyssal (below 3300 feet or 1000 meters).
The Florida Platform was separated from the continental shelf
on the north by the Suwannee Channel as early as late Upper
Cretaceous time. The lithologic character, as represented by the
exclusive nonclastic nature of sediments, of the formations rang-
ing in age from late Upper Cretaceous to Upper Eocene strongly
suggests that the entire Florida Platform became a carbonate bank
with a shallow, warm-water, marine environment during late Upper
Cretaceous time. Such environmental conditions existed continu-
ously throughout the entirety of Paleocene and Eocene time. The
platform was probably not separated into the Bahamas and penin-
sular Florida of present-day geography until Upper Eocene time;
however, much work needs to be done before such speculation can
be verified.
During Early Paleocene time, an evaporitic lagoon with a con-
siderable areal extent (fig. 41) began to develop on the carbonate
bank, the Florida Platform. Lithologic character of the Cedar Keys
Formation suggests that the evaporitic lagoon was occupied by a
shallow and warm-water marine environment only partially re-
stricted by very shallow but rather wide banks. This evaporitic
lagoon probably disappeared during Late Paleocene time, but re-
appeared intermittently during early Lower Eocene and early Mid-
dle Eocene time (figs. 42-43). However, the size of the lagoon and
the amount of evaporites produced during Lower and Middle Eocene
time were greatly reduced in comparison with that of Lower Paleo-
cene time. No evaporite beds have been found in those strata
younger than early Middle Eocene, except for minor amounts of
gypsum occurring as thin seams or veinlets in the carbonate rocks.
The Suwannee Channel acted as a natural barrier, both sedi-
mentational and faunal, between the plastic facies (in panhandle
Florida) and the nonclastic facies (in peninsular Florida) during
Paleocene and Eocene time. However, the barrier nature of the






REGIONAL LITHOSTRATIGRAPHIC ANALYSIS 87

channel gradually became less effective and finally disappeared
near the end of Upper Eocene time.
Generally, the environmental conditions in panhandle Florida
as well as in other parts of the southeastern Coastal Plain varied
from continental (supralittoral) to transitional (littoral) to shallow
marine (inner and/or outer sublittoral) continuously throughout
the entire Early Tertiary time, although shore lines and local en-
vironmental conditions were slightly different from one stage to
the other (figs. 41-44). The fact of gradual but steady spreading
of the nonclastic faces northerly and northwesterly over the plastic
faces during Paleocene and Eocene time may be the result of con-
tinued marine transgression. Some sporadic regressions occurred
during Early Tertiary time as manifested by the presence of local
and regional unconformities.
The paleogeographic patterns of Paleocene and Eocene time
were replaced in Oligocene-Miocene time by the spread of plastics
across much of the Florida peninsula.







88 FLORIDA GEOLOGICAL SURVEY-BULLETIN FORTY-FIVE


/IV
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0_ 50 =1=00 MILES
0 50 100 KILOMETERS
= ==j


EXPLANATION
LITTORAL
COARSER CLASTICS
INNER SUBLITTORAL
FINER 8 CALCAREOUS CLASTICS '\

CARBONATES 8 EVAPORITES
OUTER SUBLITTORAL
INFERRED DIRECTION OF MINOR OCEAN
FINER 8 CALCAREOUS CLASTICS CURRENTS a LITTORAL DRIFT
a CARBONATES
SCARBONATES INFERRED DIRECTION OF MAJOR OCEAN
CURRENTS
5000-- PRESENT-DAY SUBMARINE CONTOUR


Figure 41. Paleogeographic map during Paleocene (Midwayan) deposition.


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