Geologic framework of the high transmissivity zones in south Florida ( FGS: Special publication 20 )

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STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Harmon Shields, Executive Director

DIVISION OF INTERIOR RESOURCES
R. 0. Vernon, Director

BUREAU OF GEOLOGY
C. W. Hendry, Jr., Chief

SPECIAL PUBLICATION NO. 20

GEOLOGIC FRAMEWORK OF THE HIGH TRANSMISSIVITY
ZONES IN SOUTH FLORIDA

By
Harbans S. Puri and George O. Winston

Prepared by the
BUREAU OF GEOLOGY
DIVISION OF INTERIOR RESOURCES
in cooperation with
UNITED STATES GEOLOGICAL SURVEY

TALLAHASSEE
1974

fjM wiSfTY OF FLORIDA UBRR

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LETTER OF TRANSMITTAL

Bureau of Geology
Tallahassee
February 15, 1974

Honorable Reubin O'D. Askew, Chairman
Department of Natural Resources
Tallahassee, Florida

Dear Governor Askew:

The Bureau of Geology is publishing as its Special Publication No. 20 a
report entitled, "Geologic Framework of the High Transmissivity Zones of
South Florida", prepared by Dr. Harbans S. Puri and George O. Winston. We
believe this report, along with two others to follow, will provide valuable
information concerning the potential for deep subsurface waste storage in
Florida.

In 1969, the Secretary of Interior charged the U. S. Geological Survey with
the responsibility fo conducting a research program to evaluate the "effects of
underground waste disposal on the Nation's subsurface environment, with
particular attention to ground water." As a part of this charge, the U. S.
Geological Survey began investigating the hydrologic and geochemical aspects of
subsurface waste storage in Florida. In addition, through a grant (Grant No.
14-08-0001-G36) from the nationwide research program of the U. S. Geological
Survey, the Bureau of Geology, Florida Department of Natural Resources is
investigating the geologic aspects of subsurface waste storage in Florida. This
paper represents work accomplished in the South Florida area in satisfaction of
the grant instrument.

Sincerely yours,

C. W. Hendry, Jr., Chief
Bureau of Geology

Completed manuscript received
December 18, 1973
Printed for the
Florida Department of Natural Resources
Division of Interior Resources
Bureau of Geology
by
Ambrose the Printer, Jacksonville, Florida

Tallahassee
1974

iv

CONTENTS

Ak l d- I tA

Appendices ................................. ... ...... 69
Appendix 1 Electron Scanning Microphotographs of typical
carbonate lithologies ..... . . . . . . . . . . .70- 78
Appendix 2 Description of Cavities in Sun 32-2 Red Cattle and
stereo-photographs ............................ 79 83
Appendix 3 List of Wells ............. . . . . . ... 93 -96
Glossary . . . . . . . . . . . . . .... ....... 97
Index ....... ....... . .. . . . . . ......... . 99-101

c nowI e gemen . . . . . . . . . ............. .
Introduction ................. . . . . . . .....
Purpose . . . . . . . . . . . . . . . . .. ....
M methods ...... . . . . . . . . . ... . ...
Previous Studies ................ . . . . . . .....
Structure . . . . . . . . . . . . . . . . . . . .
Geologic History ............... . . . . . . ....
Stratigraphy . . . . . . . . . . . . . . . . . . ..
Pre-Eocene . . ................... .. . . . .
Upper Cretaceous.... . . . . . . . .....
Paleocene ............. . . . . . . . ...
E ocene . . . . . . . . . . . . . . . . . . ..
Lithology . . . . . . . . . . . . . . . . ..
Thickness . . . . . . . . . . . . . . . . ..
Boundaries and Relationships . . . . . . .....
Age and Correlation... . . . . . . . .....
Hydrogeologic Character . . . . . . . .....
Post-Eocene . .. . .. . .. .. . .. .. .. .. .. ....
Geology of the High Transmissivity Zones . . . . . . . .....
Definitions .. . ................... .. .. ........ .
D ata quality .. . . . . ............ ...... .....
Upper Cretaceous Cavity Zones . . . . . . . .....
Stratigraphic Setting . .. . . .............. .. . . .....
Description of Cavities ............... . . . . . . .....
Paleocene Zones ............. . . . . . . . ..
Stratigraphic Setting ............... . . . . . . .....
Description of Cavities.. . . . . . . . .....
Eocene High Transmissivity Zones ................... .. . . ....
Stratigraphic Setting .............. . . . . . . . .....
Distribution of Cavities . . . . . . . .....
Description of Cavities . . . . . . . . . . .
Hypotheses of Origin of the Cavity and Dolomitization . . . . . . .
Dolomitization ........ . . . . . . . .....
Hypothesis of Cavity Origin . ........... ...............
Evaluation of the Zones of High Transmissivity for Liquid Storage . . . . . .
Recommendations........ . . . . . . . . . .
Bibliography .............. . . . . . . .......

Page
x
1
2
3
3
5
6
11
11
11
14
14
14
23
23
23
26
29
33
33
34
37
37
38
41
41
41
41
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45
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55
56
56
57
58
63

ILLUSTRATIONS

Frontispiece Views of some of the Eocene dolostone "boulders" recovered in a junk
basket from Hamilton No. 1 Keen, Lake County, depth unknown (A);
Scanning Electron Microphotograph showing dolomite crystals and
matrix X100 (B); same enlarged X1500 to show structure of crystals
(C).

Figure Page
1. Map showing location of wells studied (listed in Appendix 3) . . . . . 4

2. Bathymetric map of Gulf-Caribbean-Antillean Region with onshore and
offshore structural features ...... . . . . . .. . . . ... 6

3. Structure contour map drawn on the top of the Upper Cretaceous . . . 7

4. Structure contour map drawn on the top of the Cedar Keys C Electric-log
marker.. .............. .... ......... ........ ...... 8

5. Structure contour map drawn on the top of the Eocene . . . . .... 10

6. Marine seismic 3000 joule arcer profile 444 (published as profile XI, Malloy
and Hurley, 1970) off Miami, Florida showing the Miami Terrace and a
Tertiary (Eocene) reef . . . . . . . . . . . . . . 11

7. Generalized geologic column for the Upper Cretaceous and the Paleocene
rocks in South Florida ....... . . . . . ............. 12

8. Isopach map of the Upper Cretaceous . . . . . ........ ....... 13

9. Isopach map of the Cedar Keys Formation . . . . . . . .. 15

10. Generalized geologic column of the Cenezoic rocks . . . . . . ... 16

11. Cycle of limestone deposition during the Eocene . . . . . . . ... 17

12. Map showing percent dolostone in carbonate and percent anhydrite in Unit
Eo-3 .......... ..... ...... .......... 19

13. Map showing percent dolostone in carbonate and percent anhydrite in Unit
Eo-2 ....................... .. ..... .. ........ 20

14. Map showing percent dolostone in carbonate in Unit Eo-1 . . . . ... 21

15. Map showing Eocene bituminous occurrences . . . . . . ...... 22

16. Isopach map of Eocene rocks ...... . . . . . . . 24

17. Map showing thickness of Eo-1, Eo-2, or Eo-3 in the Eocene . . . ... 25

18. Geologic cross section A B .................. ........ .. 27

vi

ILLUSTRATIONS Continued

19. Geologic cross section C D ............. ................ 28

20. Map showing percent grainstone in Unit Eo-3 ................... 30

21. Map showing percent grainstone in Unit Eo-2 ................... 31

22. Map showing percent grainstone in Unit Eo-1 ........... ........ 32

23. "Boulder" with two sets of tool marks from an unknown depth between 2200
and 2500 feet on the Amerada No. 1 Southern States (Well 7) Palm Beach
County ................... ........ .... ... .... . 34

24. Generalized geologic cross section showing occurrence of zones of high
transmissivity, collapse rubble and "boulders" . . . . . . ...... 35

25. A sawed face of core from Upper Cretaceous 5034- 40/2 in Amerada No. 2
Cowles Magazine (Well 6), St. Lucie County (top); Other side of the same
core (bottom) ................. ................... 36

26. Sawed face of core from Upper Cretaceous 5034 40 in Amerada No. 2
Cowles Magazine (Well 6), St. Lucie County ... . . . . . ..... 37

27. Scanning Electron Microphotograph of the same core shown as in Fig. 26,
showing cementation by medium crystalline dolomite . . . . . .... 38

28. Same as Fig. 27, enlarged X1500 showing faces of crystals and intergranular
porosity .............. ......... ........... ........ 39

29. Isolith map of upper bank dolostone and cavity distribution in Upper
Cretaceous .. . ...................... . . . . . . 440

30. Isolith map of bank dolostone and high transmissivity distribution in Cedar
Keys Formation .................. . . . . . . . . 42

31. Generalized Cedar Keys and Upper Cretaceous bank dolomite sections based
on Electric-log of Coastal No. 1 State (Well 52) ..... . . . . . ..... 43

32. Cycle of dolomitization ..... . . . . . . .... . .. 44

33. Occurrence of high transmissivity in Unit Eo-3 . . . . . . ...... 46

34. Occurrence of high transmissivity in Unit Eo-2 . . . . . . ..... 47

35. Occurrence of high transmissivity in Unit Eo-1 . . . . . . ..... 48

36. Photograph of upper dolomite zone at 2030 feet in U. S. Gypsum Core (Well
30) showing peaty partings, "beach rock" rubble, and sucrosic dolomite zones 49

vii

ILLUSTRATIONS Continued

37. Photograph of the top of the dolomite zone at 2046 feet in U. S. Gypsum
Core (Well 30) showing peaty partings and limestone in irregular contact with
incompletely dolomitized limestone . . . . . . ....... . . ..... 50

38. Photograph of the basal contact of the dolomite zone at 2046V2 feet in the U.
S. Gypsum Core (Well 30) showing dolomite grading into incompletely
dolomitized limestone, underlain by peaty partings in limestone with dolomite
crystal inclusive . . . . . ......... .................. 51

39. Photograph of the core at 2050 feet in the U. S. Gypsum Core (Well 30)
showing preferred horizontal orientation of vug porosity in dolomite zone . 52

40. Sawed face of same core in Fig. 39 .... . . . . ....... 53

41. Map showing ratio of feet of aquifer per foot of aquitard and thickness of
aquiclude in Unit Eo-3 . . . . . ......... .. ............ 59

42. Map showing ratio of feet of aquifer per foot of aquitard and thickness of
aquiclude in Unit Eo-2 .................................. 60

43. Map showing ratio of feet of aquifer per foot of aquitard and thickness of
aquiclude in Unit Eo-1 ................... .. ........... 61

44. Scanning Electron Microphotograph of Skeletal limestone from Unit Eo-2,
100% coarse grained (depth 2435 50 ft.), Gulf-Cal. Block 46 (Well 46)
Monroe County (X100) ........... . . . . . . . . ..... 62

45. Same enlarged X2100 to show calcite crystals . . . . . . . 63

46. Scanning Electron Microphotograph of Skeletal limestone from Tampa Stage
(depth 1160-70 ft.), Coastal No. 1 State (Well 52) Monroe County (X100) . 64

47. Same enlarged X1500 to show calcite crystals .. . . . . . . . 65

48. Scanning Electron Microphotograph of micritic limestone from Unit Eo-2
(depth 2650 60), Peninula No. 1 Cory (Well 54) Monroe County (X100) . 66

49. Same enlarged X2000 to show calcite crystals . . . . . . ...... 67

50. Scanning Electron Microphotograph of lithographic dolostone from Unit Eo-3
(depth 3540 50), Coastal No. 1 State (Well 52) Monroe County (X100) . 68

51. Same enlarged X1500 to show dolomite crystals . . . . . . .... 69

52. Scanning Electron Microphotograph of dolostone, microcrystalline,euhedral,
from Unit Eo-1 (depth 1470 80 ft.) Coastal No. 1 State (Well 52) Monroe
County (X100) ......... ......... ........... ....... 70

53. Same enlarged X1000 to show faces of dolomite crystals . . . . .... 71

viii

ILLUSTRATIONS Continued

54. Scanning Electron Microphotograph of dolomite, fine crystalline, euhedral,
Tampa Stage (depth 1035 ft.) Coastal No. 1 State, Monroe County (X100) . 72

55. Same enlarged X1000 to show faces of dolomite crystals . . . . .... 73

56. Scanning Electron Microphotograph of dolomite, medium crystal, sucrosic,
euhedral, 20% vugs and intragranular, porosity, Eo-3 (depth 3440 3500 ft.),
Mobil No. 1 Babcock Ranch (Well 10), Charlotte County (X100) . . ... 74

57. Same enlarged X530 to show faces of dolomite crystals . . . . .... 75

58. Scanning Electron Microphotograph of dolomite, very finely crystalline,
anhedral, Upper Cretaceous, bank dolomite, (depth 5210-20 ft.) Gulf-Cal.
Block 46 (Well 46), Monroe County (X100) . . . . . . ...... ...... 76

59. Same enlarged X1500 to show anhedral crystal arrangement . . . .... 77

60. Photograph of 2230 foot level in Sun 32-2 Red Cattle . . . . . ... 78

61. Photograph of 2258 foot level in Sun 32-2 Red Cattle . . . . . ... 79

62. Photograph of 2272 foot level in Sun 32-2 Red Cattle . . . . . ... 80

63. Photograph of 2308 foot level in Sun 32-2 Red Cattle . . . . . ... 81

64. Photograph of 2376 foot level in Sun 32-2 Red Cattle . . . . . ... 82

65. Photograph of 2436 foot level in Sun 32-2 Red Cattle . . . . . ... 83

66. Photograph of 2496 foot level in Sun'32-2 Red Cattle . . . . . ... 84

ACKNOWLEDGEMENTS

We wish to acknowledge the support of the U. S. Geological Survey, who,
under a directive from the Secretary of the Interior to evaluate the effects of
subsurface waste disposal in the United States, have provided financial support
for this study under U. S. Geological Survey Grant No. 14-08-0001-G36.

Several persons and organizations have contributed to this study of the
high transmissivity zone. We wish to express our appreciation to the Sun Oil
Company for providing photographs from their photo survey of the zone and for
permission to publish these in this study, and to the Exxon Company for
collecting and providing drilling-time data on many wells in this area. We have
benefited from discussions with colleagues, particularly J. E. Banks and E. J.
Henderson, for their first-hand experiences in drilling through the cavernous
zones on drilling problems encountered by the industry.

Dr. R. O. Vernon, Director, Division of Interior Resources, who has done
much initial work on this zone, and C. W. Hendry, Jr., Chief, Bureau of Geology,
contributed advice and encouragement.

Francis A. Kohout, Mathew I. Kaufman and Glen L. Faulkner, U. S.
Geological Survey, were most helpful in presenting the geohydrological problems
involved in this study.

GEOLOGIC FRAMEWORK OF THE HIGH TRANSMISSIVITY
ZONES IN SOUTH FLORIDA

By
Harbans S. Puri and George O. Winston

INTRODUCTION

Streams and rivers have been the perennial dumping grounds for industrial
and human wastes. The passage of the Federal Clean Streams Act of 1966, and
the stricter reinforcement of pollution control laws already on the books, have
discouraged the discharge of industrial and municipal wastes into surface waters.
Consequently, a demand has arisen for methods in which industrial and human
wastes can safely be discharged into the subsurface. The deep saline part of the
Floridan aquifer has been, for years, used by the oil industry for the injection of
oil-field brines. Deep injection wells for industrial waste disposal are currently
also using the lower saline part of the Floridan aquifer. There are indications of
an increasing necessity to use the deep, high-salinity part of the aquifer for
subsurface liquid-waste injection and to use the brackish-fresh water part for
fresh water storage (see Vernon, 1970, p. 33).

The Floridan aquifer underlies the entire State of Florida and adjoining
parts of Georgia, Alabama, and South Carolina. The upper fresh water part of
the aquifer is the source of drinking water for thousands of municipalities and
irrigation systems. The Floridan aquifer is over 2,000 feet thick and consists of
"very" porous and permeable limestones or dolostones with widely varying
porosities and permeabilities. Under the force of gravity, relatively fresh water in
the upper part of the aquifer flows seaward. In the Kendall sewage disposal well
(No. 48) between 1800 and 1900 feet, the salinity increased nearly 3 fold from
6400 to 17,600 mg/1 chlorides. One thousand feet deeper, at 2947 feet total
depth, the salinity had risen to 19,300 mg/1, the concentration of sea water.
Data to establish the direction and extent of the flow in the salt-water part of
the aquifer (from 1000 feet to 3,000 feet below mean sea level) are not available
at this time.

Industrially, it is important to understand the hydrologic and geologic
factors which control horizontal and vertical fluid movements in the aquifer in
order to be able to predict the ultimate direction of migration and rate of flow
of the liquid wastes which may be injected into the system.

In 1969, the Secretary of Interior charged the U. S. Geological Survey
with the responsibility of conducting a research program to evaluate the "effects
of underground waste disposal on the Nation's subsurface environment, with
particular attention to ground water." As a part of this charge, the U. S.

BUREAU OF GEOLOGY

Geological Survey began investigating the hydrologic and geochemical aspects of
subsurface waste storage in Florida. In addition, through a grant (Grant No.
14-08-0001-G36) from the nationwide research program of the U.S. Geological
Survey, the Bureau of Geology, Florida Department of Natural Resources is
investigating the geologic aspects of subsurface waste storage in Florida. This
paper represents work accomplished in the South Florida area in satisfaction of
the grant instrument.

PURPOSE

The purpose of this study is to provide answers to the nature of the
geologic framework which constitutes the environment of a potential
waste-storage system in South Florida. The research was undertaken to provide
data for or to aid in the study of the following problems:

a. Delineation of lost circulation zones as potential waste-disposal and
fresh water storage zones, and the determination of thickness, spatial
distribution and number of zones of high transmissivity.
b. The lithologic nature and lateral extent of the confining beds and
their capability of confining wastes to the injection horizon.
c. Direction and patterns of movements of fluids within the
waste-disposal zones under natural conditions.
d. Possible interactions between liquid wastes and the enclosing rock or
fluids in the injection zones, and thereby forecasting the ultimate
disposal of the liquid wastes.
e. Provide field data for use in the development of theoretical and lab
models of the aquifer.
f. Establish whether the cavity system containing saline water in South
Florida is a part of the same hydrologic regime as the cavities
developed in the fresh-water aquifer in the northern part of the
peninsula.

The following geologic research in fulfillment of the objectives outlined
above was conducted:

1. The high transmissivity zones in South Florida were defined,
delineated, and mapped.
2. The dense zones between the lower and upper parts of the Floridan
aquifer were defined, delineated, and mapped.
3. The geologic horizon, especially at the top and bottom of the zones
of high transmissivity, were established through a study of rock
cuttings and cores.

SPECIAL PUBLICATION NO. 20

METHODS

To understand the origin and distribution of the cavities, it is necessary to
understand the geologic setting in which they are found. As the major portion of
the high transmissivity zone is concentrated in the Eocene, an intensive study of
the geology of this system was undertaken. The narrow belt of high
transmissibty in the Paleocene and Upper Cretaceaous contained little
stratigraphic data, therefore, only an incomplete study of this section could be
made.

The pattern of exploration drilling in south Florida and the general lack of
returns from the lower Eocene resulted in the widely spaced control grid seen on
the facies maps. A survey of all oil tests was made for availability of samples in
the Eocene. Wells with the most complete set of samples (see Fig. 1) were
selected for examination. Of great value was the U. S. Gypsum Company mineral
test well in Collier County (Well 30) which cored much of the Eocene section.

Electric log tops were correlated with sample data when possible. As the
top of the Eocene is almost always behind casing, and therefore not logged,
paleontologic tops were used in mapping Eocene thickness and structure.

Sun Oil Company's set of stereo photos of the Eocene from a well in south
Florida was the basis for describing the character of the voids. Drilling time logs
and notations of the driller were vital for accurate figures on placement and
thickness of cavities and caverns.

The personal observations of geologists in the oil industry who witnessed
the drilling of cavernous zones were also valuable in making proper geological
interpretation.
PREVIOUS STUDIES

Studies on solution and zones of high transmissivity have been published
by Vernon (1947, 1951, 1970), and Garcia-Bengochea and Vernon (1967), Puri
and Banks (1959), Chen (1965), Hanshaw (1965, 1970), Kohout (1965, 1967),
Henry and Kohout (1972) and Henry and Hilleke (1972).

Kohout (1965) used the name "Boulder Zone" for the saline part of the
Floridan aquifer. The term "Boulder Zone" is misleading as no true boulders are
present. However, the term has been used for decades for this zone because the
drilling action during penetration was as if the zone consisted of boulders. This
interval represents a highly porous zone of vug and occasionally cavern-size
openings and is referred to in this paper as the zone of high transmissivities or as
cavity zones.

BUREAU OF GEOLOGY

10 0 1 2 MILES

Figure 1 Map showing location of wells studied (listed in Appendix 3)

SPECIAL PUBLICATION NO. 20

There are two hypotheses on the circulation pattern in the cavernous zone.
These include temperature anomalies and hydrologic heads, with accompanying
geochemical changes that occur along the interface of water bodies that differ in
soluable salts to account for the dolomite. Temperature anomalies in oil wells
led Kohout (1965, 1967) to postulate that cold seawater in the Gulf of Mexico
and the Florida Straits flows inland into the deep saline part of the Floridan
aquifer through the very permeable dolostones. A convection pattern is
postulated by Kohout, where dense, cold, sea water would rise as it was
progressively warmed by geothermal heating. It then mixes with the fresh-water
of the upper Florida aquifer and discharges back into the Gulf of Mexico and the
Straits of Florida. Henry and Kohout (1972) and Henry and Hilleke (1972) offer
supporting evidence based on the simulation of actual field conditions by a
computer model.
Vernon (1947, 1951, 1970) believed that geohydrologic heads, resulting in
part from sea-level fluctuations, created porous and impervious beds by the
dissolution and precipitation of limestone, dolostone, and gypsum. The direction
of water flow was established in response to hydrologic heads existing at various
levels in various geologic periods (Vernon, 1970).

The present study indicates that several distinct zones of high and low
transmissivity are present in the Floridan aquifer, and that the entire Floridan
aquifer in South Florida may not act as one hydrologic unit. Field data
measurements are needed to establish definite directions and rates of circulation
in the Floridan aquifer.

STRUCTURE

Major geologic structures in South Florida are superimposed on the
bathymetric map of the Gulf-Caribbean-Antillean region as shown on Figure 2.
Most of the features appear on structure contour maps of the top of the
Cretaceous (Fig. 3) and of the Paleocene Cedar Keys C bed, the highest bed on
which the writers believe that a valid regional structure map can be made. This
latter bed apparently was not affected by solution, collapse, or erosion, as were
parts of the overlying Eocene.

On this map the southerly dip of approximately 15 feet per mile changes
below the 3600 foot contour into a large, essentially flat trough that extends
throughout most of Hendry, Lee, and Collier counties. Lack of control precludes
an accurate determination of the structure in the Broward County area.

South of the north branch of the Broward Trough, the Forty Mile Bend
High and the Largo High are prominent. The most distinctive negative feature is
the center of the Basin off the modern southwest coast.

BUREAU OF GEOLOGY

Figure 2 Bathymetric map of Gulf Carribean Antillean Region with
onshore and offshore structural features.

The structure and mode of formation of the northern Florida Straits, the
eastern margin of the Eocene sedimentary province, is still a matter of
controversy, but the features seem to have appeared in Late Upper Cretaceous
or Early Palocene time, probably by faulting.

GEOLOGIC HISTORY

The South Florida Basin, a segment of the Florida-Bahama Platform, has
been an area of slow subsidence since at least Upper Jurassic time. During this
time, the environment of the South Florida Basin has been essentially that of a
shallow to deep shelf supporting carbonate and evaporitic cyclic deposition
(Winston, 1972). During the Jurassic and Lower Cretaceous, the Platform

SPECIAL PUBLICATION NO. 20

~J~.I,000

o10 o 30 MILES

Figure 3 Structure contour map drawn on the top of the Upper
Cretaceous.

BUREAU OF GEOLOGY

CONTOUR INTERVAL 100'

10 0 10 0o 30 MILES

Figure 4. Structure contour map drawn on the top of the Cedar Keys C
Electric-log marker.

SPECIAL PUBLICATION NO. 20

extended from the Florida Escarpment in the west, eastward to the
Blake-Bahama Escarpment and from Southern Georgia into the northern part of
Cuba (Fig. 2) and was bounded by a barrier reef (Bryant et. al. 1969). In Upper
Cretaceous time, however, this pattern changed, resulting in the deposition of a
new lithologic sequence dominated by chalk.

During the Upper Cretaceous, major tectonic activity commenced in Cuba,
during which the southern Florida Straits were probably formed, thus limiting
the once broad South Florida Basin to the area rorth of the Pine Key Arch (Fig.
2). The southern margin of the Straits is highly faulted near Cuba. The northern
margin of the Straits lies south of the Keys and less intensive faulting is indicated
here by the development of the Pourtales and Miami Terraces. The Northern
Straits did not come into existence until latest Upper Cretaceous or Paleocene.

Following the formation of the Northern Straits a narrow Upper
Cretaceous bank system, possibly behind a windward reef, developed in the
vicinity of the present edge of the Continental Shelf and the modern east coast
of Florida. Deposition of bank-type carbonate sediments continued through
much of Paleocene time. The presence of Paleocene evaporites suggests that a
reef may have extended completely around the edge of the Continental Shelf,
thus restricting sea water interchange.

In Eocene time, the barrier reef, as shown on a marine seismic profile off
Miami (Fig. 5 and 6) was probably discontinuous, as evaporite deposition in the
Eocene is very limited. The presence of a high energy environment near the
modern southeast coast is indicated by the presence of thick, clean, grainstones.

The deposition of numerous peat and/or lignite beds indicates that parts of
the sea floor were exposed during the Eocene. It would appear from our study
that these minor Eocene unconformities are related to the formation of the
Eocene cavities.

Following deposition of the Eocene, a large unconformity developed
which when mapped in detail (see Vernon, 1951) shows relief of as much as 200
feet. Karst topography, however is very local in extent, (see Fig. 5), and appears
only on detailed mapping. It consists of an occasional sinkhole.

In Oligocene, Miocene, Pliocene, and Pleistocene times, the South Florida
Basin for practical purposes had ceased to exist. Several major and minor
unconformities with corresponding transgression and regression of the sea occur
during this interval. The complex carbonate-clastic facies relationships within
this section are not yet fully understood.

BUREAU OF GEOLOGY

!P 0 0 A0 MILES

Figure 5. Structure contour map drawn on the top of the Eocene.

SPECIAL PUBLICATION NO. 20

-- MIAMI TERRACE t |
REEF
RFFF

Figure 6 Marine seismic 3000 joule arcer profile 444 (published as profile
XI, Malloy and Hurley, 1970) off Miami, Florida showing the
Miami Terrace and a Tertiary (Eocene) reef.

STRATIGRAPHY

GENERAL

Really, most of the zones of high transmissivity are confined to the
Eocene, therefore, this section was studied more intensively than were the Cedar
Keys and Upper Cretaceous cavity zones which occur only in a narrow belt along
the east coast of Florida, as is discussed later in the report.

PRE EOCENE

UPPER CRETACEOUS: PINE KEY GROUP

In the South Florida Basin, the Pine Key Group (Meyerhoff, 1973) is
composed almost entirely of chalk, either limestone or dolostone. Along the
Keys and in St. Lucie County, massive, brown, fine to medium anhedral

BUREAU OF GEOLOGY

crystalline, shallow bank-type dolostones appear in the upper portion of the
Group (see Figs 7 and 8). As these parallel the present location of the Florida
Straits, their origins are probably related.

eost - west

Figure 7 Generalized geologic column for the Upper Cretaceous and the
Paleocene rocks in South Florida.

SPECIAL PUBLICATION NO. 20

Ip~ JOLE $

Figure 8 Isopach map of the Upper Cretaceous.

BUREAU OF GEOLOGY

PALEOCENE: CEDAR KEYS FORMATION

The Cedar Keys Formation overlies the Upper Cretaceous conformably and
underlies the Eocene conformably. Regionally it is composed of dolostones and
anhydrite. The dolostone is usually gray or brown, crystalline, euhedral, and is
frequently evaporitic in origin. Dolomite crystal size is usually fine to very fine,
but occasionally fine crystalline and sucrosic textures were observed. The top of
the Cedar Keys' thick anhydrite section usually occurs about 200 feet below the
top of the formation, but anhydrite occasionally may be present at the contact.
In some wells, the Cedar Keys dolostone immediately below the Eocene is a
dolomitized version of the grainstone skeletal limestones of the Eocene. This,
coupled with the occasional presence of anhydrite and evaporitic dolostone in
the lower part of the Eocene, suggests regional interfingering of lithologies at the
Eocene-Cedar Keys boundary; therefore, for mapping and study purposes, the
top of Cedar Key C marker (see Figs. 4, 7, 9) was used.

EOCENE

As there are no reliable regional markers in this Series, it was subdivided
for mapping purposes into three equal (Fig. 10) parts, Eo-1, Eo-2, and Eo-3.

LITHOLOGY

LIMESTONE

The lithology of the Eocene beds, their thickness and occurrence of
cavities is summarized in Figure 10. Several Eocene limestone textural types are
combined into a sedimentary cycle (Fig. 11), which is usually more complete in
Eo-1 than in Eo-2 or Eo-3.

Within the Eocene section, two textures of limestone predominate.
Skeletal grainstone with 80-100% very fine to medium grains (Bed 4, Fig. 11) is
usually tan, or cream. Foraminifera are common. Cementation is weak,
frequently permitting the grains to be disassociated by drilling. Only very small
amounts of micrite or cement are present.

The other type, a skeletal packstone, contains only 50-70% very fine
broken skeletal grains and much chalky micritic interstitial material (Bed 3, Fig.
11). Color is predominately cream, but tan and white are occasionally seen.
Foraminifera are not common.

Chalky or dense micrite are infrequently encountered.
Dark colors in Eocene limestone are conspicuously absent.

SPECIAL PUBLICATION NO. 20

So Figue LI

Figure 9

Isopach map of the Cedar Keys Formation.-

16 BUREAU OF GEOLOGY

SERIES FORMATION I

4' (Undivided) 50' Sand, ool

TAMIAMI 150' ..green a
AlO FORMATION /

4 HAWTHORN
FORMATION Sandstone
S. . . shale, br
l 500' loose she
- limestone
MW phosphor
u TAMPA
0 FORMATION
E 200'

SSUWANNEE White
S LIMESTONE chalky c
00 I sandy m
< 200'

Eo-I OCALA
GROUP

Avon Park
Limestone

wL Eo-2 /e
z Tan to
calcarenit
W 2500' calcarenit
Occasion
S/ medium f
Loke City frequently
0 cavities
Limestone Dolostone
fine crys
large cavi
Cavities
thick ma

Eo-3 Oldsmor

; siltstone, olive drab;
own or olive drab;
lls; clay;
white, sandy;
ite throughout

cream
e and cnalky
:e.
al zones of fine to
ine crystalline dolostone
y with large vugs and

e, cryptocrystalline to
taline, with occasional
ties
from 5 inches to 90 feet
inly in the lower part.

Figure 10 Generalized geologic column of the Cenezoic rocks.

SPECIAL PUBLICATION NO. 20

Eocene (Principally Avon Park)

Figure 11. Cycle of limestone deposition during the Eocene.

BUREAU OF GEOLOGY

DOLOSTONE

Dolostone is usually dark brown or tan but may be dark gray, or light
gray. Crystal sizes range from crypto to coarse and are anhedral, euhedral or
sucrosic in arrangement; the sucrosic type is essentially a porous version of the
euhedral variety. The anhedral form is the most common and the sucrosic form
the least. These dolostone types can change from one to another in a fraction of
an inch.

Additionally, dolomite is found as separate crystals "floating" in micritic
or chalky limestones. These crystals range from micro to coarse grain in size, and
their concentration ranges from an occasional crystal to a 95% replacement of
the limestone.

Dolostone in the Eocene occurs either as thick discrete beds, or as thin
zones within limestone beds (Fig. 10). In Eo-3 (Fig. 12) the dolostone forms a
major portion of the section. In Eo-2 (Fig. 13) it is a major constituent only in
the extreme northwest part of the study area; in Eo-1 (Fig. 14) it is a major
fraction only in the northern part. Examination of the well cuttings indicates
that dolomitization took place preferentially in the chalky matrix limestone
type.
ANHYDRITE

Anhydrite is a minor constituent regionally, but can be of some
importance locally. It is confined to Eo-3 and Eo-2 (Figs. 12 and 13). In Eo-3 it
is found in the western part of the study area as beds or as nodules. It is white to
gray, transluscent and amorphous in texture. In Well 30 several thin beds of dark
brown crystalline anhydrite occur. This occurrence, of local origin, is probably
related to an Eocene collapse zone on the Sunniland Field structure.

Eo-2 anhydrite is also both bedded and nodular, and is confined to
western Collier County and Manatee County.

LIGNITE AND PEAT

In Eo-3 peaty partings and very thin layers of peat are common, occurring
in a southward trend through the central part of the area (Fig. 15). Lignite was
not observed in this unit.

In Eo-2, peaty partings, peat and lignite all are found in a trend extending
southeastward across the study area (Fig. 15). Several beds of lignite were
present in Well 1 and Well 13. Lignite varies in thickness from a trace (Well 48)
to 30 feet (Well 1).

SPECIAL PUBLICATION NO. 20

0 50

I, '100%1

PERCENT DOLOSTONE
IN CARBONATE

ANHYDRITE CONTOUR INTERVAL: 50 PIERCE T

25 11 11 11 11

10 0 0 MILES

Figure 12 Map showing percent dolostone in carbonate and percent
anhydrite in Unit Eo-3.

c/\

BUREAU OF GEOLOGY

Figure 13 Map showing percent dolostone in carbonate and percent
anhydrite in Unit Eo-2.

SPECIAL PUBLICATION NO. 20

12 9 v 10 NU"'

Figure 14 Map showing percent dolostone in carbonate in Unit Eo-1.

BUREAU OF GEOLOGY

10 0 MILES

Figure 15 Map showing Eocene bituminous occurrences.

SPECIAL PUBLICATION NO. 20

THICKNESS

Thickness of the total Eocene varies between 2300 feet and 2960 feet,
averaging some 2600 feet. (Fig. 16).

Thin areas occur over the Martin, Largo, and Charlotte Highs (Fig. 2).
Prominent thick areas are found in the central part of the study area and in the
center of the Basin off the modern southwest coast.

As all units in each well had exactly the same thickness one isopach map
suffices for all subdivisions (Fig. 17).

BOUNDARIES AND RELATIONSHIPS

The lower boundary of the Eocene with the Cedar Keys Formation is
everywhere conformable. It is gradational in local areas, but electric log
correlations can be easily made with occasional assistance provided by lithologic
examination of well cuttings. The lower contact was picked on the sharp break
at Cedar Keys Unit C. Here the beds change from grainstone or packstone of
Units A/B (or dolomitized version thereof) at the top of the unit to a very fine
and microcrystalline, euhedral, frequently sucrosic, gray dolostone below.

Units A/B are therefore included in Eo-3. At times this contact may be
difficult or impossible to pick in samples, but surprisingly the electric log
character will remain quite consistent.

The upper boundary of the Eocene with Oligocene and Miocene beds is
everywhere unconformable, exhibiting as much as 200 feet of relief (see Fig. 5).
In the southeast part of the study area most of the Ocala portion of the Eocene
is missing.

The percentage of grainstone carbonate (or absence of chalky matrix
material) is greatest near the southeast coast and in the Keys, where most of the
section tends to be composed of grainstone. To the northwest, the Eocene
becomes progressively more chalky and is dominated by packstone.

AGE AND CORRELATION

The presence of lower, middle, and upper Eocene Stages are well
established from the extensive fauna in these lithologic units. An attempt was
made in South Florida to identify the boundaries of formations by microfauna,
but extensive replacement by dolomite obliterated the finer features of the
various species, and even in the limestone, diagnostic fossils were uncommon.

BUREAU OF GEOLOGY

10 20 MILES

Figure 16 Isopach map of Eocene rocks.

SPECIAL PUBLICATION NO. 20

I 0 MILLs

Figure 17 Map showing thickness of Eo-1, Eo-2, or Eo-3 in the Eocene.

BUREAU OF GEOLOGY

Lack of good samples in most wells was also a handicap. Consistent
paleontologic subdivisions of the Eocene in South Florida were not possible,
with the exception of the Ocala at the top of the section. The Oldsmar tops vary
widely between wells, and are not suitable for mapping purposes. Lack of any
consistent lithologic horizon in the almost universally porous limestone, as well
as the erratic nature of dolostone occurrence, precluded using lithologic
parameters for subdividing the section.

Lacking lithologic or paleontologic criteria, the Eocene was, therefore,
subdivided into three equal intervals in each well. These units in descending
order are designated as Eo-1, Eo-2, and Eo-3, and are roughly equivalent (in
Manatee County) to Ocala-Avon Park, Lake City, and Oldsmar paleontologic
tops, respectively. That the top of the Oldsmar moves capriciously up and down
the section has long been known. (see Fig. 18, 19) One contributing factor is
dolomitization, which in some instances has destroyed diagnostic fossils, thus
displacing the faunal top of the formation downward from the true top. Where
dolomitization is not a factor, two other explanations can account for the lack
of fossils.

1. Larger Foraminifera, which are a major component of the fauna, thrive on
open, lime bank facies, under normal saline conditions. Excessive run-off from
the mainland would change salinity conditions, which are detrimental to their
growth. Pure calcilutites or calcarenite (Suwannee and Ocala) invariably are
associated with a true bank fauna. Fluctuations in sea level would cause the
fauna to migrate seaward. Supersaline conditions in the area would discourage
growth of normal saline forms. Occasional presence of anhydrite is indicative of
supersaline conditions, which are detrimental to the growth of larger
Foraminifera. Cyclic solution and replacement of calcite which was formed in
some of the supratidal dolostones, would destroy tests.

2. Another hypothesis that would explain the poor faunal record is the
migration southward in space and upward in time of the environment in which
bank forms existed. This hypothesis would not require tectonic activity other
than the gradual sinking of the area, an activity characteristic of the Basin since
the Jurassic.

HYDROGEOLOGIC CHARACTER

LIMESTONE

Permeable beds in Eocene limestone are associated with both the
grainstone and with chalky packstone. In the grainstone, porosity in a few core
samples was measured as high as 35% with permeability occasionally as high a 1

INDEX OF CROSS SECTIONS

CROSS SECTION

A-B

Florida

DATUM SURFACE
HORIZONTAL SCALE NONE
VERTICAL SCALE
0

500 FT

E Anhydrite
E Dolo stone
E Limestone
E3 Sandstone
EO Shale
E Missing Sample
Impermeable
m High Permeability
B Low Permeability

2000

30ee00

C D
30 Surface 25 50 6

INDEX OF CROSS SECTIONS

CROSS SECTION

C-D

Florida

DATUM SURFACE
HORIZONTAL SCALE NONE
VERTICAL SCALE
0

500 FT

Anhydrite
Dolo stone
Limestone
Sandstone
Shale
Missing Sample
Impermeable
High Permeability
Low Permeability

4000

If

4000

SPECIAL INFORMATION NO. 20

darcy. During drilling of wells, drilling fluid is frequently lost in this lithologic
type. In chalky packstone beds, porsity in a few core samples was found to be as
high as 33%, but permeability was low averaging 5 millidarcies. Although the
chalky beds will transmit water, it will be at such a slow rate that they can be
considered as aquitards rather than as aquifers. Dense limestone aquicludes in
the Eocene are rare.

DOLOSTONE

Sucrosic dolostone can have porosity as high as 20% with excellent
permeability. Vug porosity in dolostone is frequently low, but permeability can
be quite high when the vugs are well connected. Porosity and permeability are
extremely high in the cavernous zones.

The high porosity (23%), low permeability (2 millidarcy), microcrystalline
or chalky dolostone would tend to act as an aquitard. Dolostone aquicludes are
hard to evaluate. Although a considerable thickness of non-porous anhedral
dolomite is usually present in Eo-3, its impermeable nature depends on the
absence of fractures. Because fractures can rarely be identified in cuttings (the
major source of lithologic data for this study) the regional state of fracturing
could not be determined. The Sun Oil Company's photos of the Eocene in their
Red Cattle 32-2 Well showed no large open vertical fractures. Lacking data to
the contrary, we tentatively conclude that dense dolostone acts as an aquiclude.

POST- EOCENE

There is a major erosional unconformity at the top of the upper Eocene,
which in South Florida is represented by the Ocala Group. Generally the Ocala
Group is overlain by 200 to 300 feet of Suwannee Limestone, consisting of very
porous, white, calcarenite, chalky calcarenite and sandy micrite. The base of the
Suwannee Limestone is marked by the occurrence of Streblus mexicana, S.
byramensis, and Coskinolina floridana and its top is marked by an abundance of
Miogypsina hawkinsi. Where the Ocala Group is missing, in the southernmost
peninsula and in the Florida Keys, the Suwannee Limestone unconformably
overlies the Avon Park Limestone.

Oligocene Suwannee Limestone is overlain by lower and middle Miocene
(Tampa Stage and Hawthron Formation) which consists of about 700 feet of
intermixed varying lithologies and percentages of sandstone, siltstone, olivedrab
shale, brown or olive loose shells, white sandy limestone, with phosphorite or
plastic clay. The section, especially the clay, has a very low permeability and acts
as an aquiclude over the porous and permeable Suwannee Limestone.

BUREAU OF GEOLOGY

'lP9 o0 W MLSI

Figure 20 Map showing percent grainstone in Unit Eo-3.

C-YTr ln'-'r'l'T"'Ti7p'rL*T"I_ ,,

SPECIAL PUBLICATION NO. 20

O 3*o0 MILES

Figure 21 Map showing percent grainstone in Unit Eo-2.

BUREAU OF GEOLOGY

m

CDISAOTE

Ig~e~~e~p LIS

Figure 22 Map showing percent grainstone in Unit Eo-1.

SPECIAL INFORMATION NO. 20

Beds of the upper Miocene Tamiami Formation, consist of approximately
150 feet of limestone, calcareous clay, green-aluminous clay, and sand. The
Miocene is overlain by Pleistocene, which includes numerous formations
including the Miami Oolite, Anastasia Formation, Caloosahatchee Formation,
Fort Thompson Formation and the Key Largo Limestone.

GEOLOGY OF THE HIGH TRANSMISSIVITY ZONES

DEFINITIONS

"BOULDER ZONE"

The beds referred to as the "Boulder Zone" contain no boulders. The zone
was named by well drillers in the early days of south Florida oil exploration for
an interval spanning the lower part of Eo-2 and Eo-3. This is the zone of great
permeability and characterized by an intricate vug and large cavity porosity.
Pieces of the rock forming the roof of an occasional cavity, collapse breccia, or
cavern are broken off by drilling activity and these fragments fall into the hole,
are rolled between the drill rod and the walls of the hole to create real
"boulders" (Fig. 23).

Another phenomenon lending to "boulder" type drilling involves the loss
of drilling fluids into these permeable zones. The fluid volume to the surface is
reduced, and large cuttings which cannot be lifted by the reduced fluid flow
settle to the bottom of the hole. These cuttings create pipe and bit-sticking
problems which has drilling characteristics similar to drilling depositional
"boulders". Where total or partial loss of fluid circulation occurs in the hole,
"Boulder Zone" drilling problems can be expected to occur throughout that
zone.

HIGH TRANSMISSIVITY ZONES

"High transmissivity zone" is a hydrologic term implying the ability of a
thick vertical section to transmit fluids.

Five discrete zones of high transmissivity occur in cavernous carbonate beds
of upper Cretaceaous, Paleocene and Eocene age and their distribution is shown
on a generalized geologic cross section (see Fig. 24). The cavities tend to rise
stratigraphically away from the Florida Straits in a northerly direction.

BUREAU OF GEOLOGY

DATE QUALITY

The only reliable way to be able to obtain data on the position, shape and
thickness of the cavities is to make a stereo-photographic survey. Unfortunately,
this type of data is available on only one well (Sun Red Cattle 32-2). Secondary
data, such as drilling time logs, notations of "boulders", "cavity", or "caverns"
interpretations from geophysical logs, or occurrences of lost circulation had to
be used to indicate the general distribution of the zones of high transmissivity.

No isopach maps were prepared of the zones of high transmissivity, as data
on the base of the zone was unobtainable. The top of these zones can be picked
by using the above-mentioned criteria. As the lost circulation persists until the
depth where the Eocene high transmissivity zone is cased off, there is very little
available data to draw the base of zones.

Figure 23 "Boulder" with two sets of tool marks from an unknown depth
between 2200 and 2500 feet on the Amerada No. 1 Southern
States (Well 7) Palm Beach County.

f Srfacs 'A i-' F -.

mFW
0

1000 -

02000

. 3000

70
0 0 5000-

* 8
0

Eo-I

Eo-2

Eo-3

U P

T A C
T A C E

Rumu~

LOWER CRETACEOUS

DATUM-SURFACE
op

I OCw 1

t100

ed m079
0 0 10 0 So ILU
NK SCA

jeoo.s

R C R E

P E

Bo~o

0.01

/11
BLtOERS~

SU S

BUREAU OF GEOLOGY

Figure 25 A sawed face of core from Upper Cretaceous 5034 40/2 in
Amerada No. 2 Cowles Magazine (Well 6), St. Lucie County
(top); Other side of the same core (bottom).

SPECIAL PUBLICATION NO. 20

UPPER CRETACEOUS CAVITY ZONES

STRATIGRAPHIC SETTING

The Upper Cretaceous (Pine Key Group, Meyerhoff, 1973) in south
Florida is composed almost entirely of limestone or dolostone chalk. This
lithology is replaced in the upper part of the Pine Key Group, along the modern
east coast and the Keys, by brown anhedral dolostone. In Wells 36 and 37, in the
lower part of the Upper Cretaceous, the Card Sound Dolomite (Winston, 1971)
of similar texture, replaces the chalk. Where the Card Sound Dolomite is present,
the upper dolostone appears to be absent.

The upper dolostone was probably deposited at the back edge of a reef
chain occupying an offshore position near the present continental slope forming
the western side of the northern Straits of Florida.

A core contributed by E. J. Henderson (Figs. 24 to 28) from 5034 5040
feet in Well 6 shows a rubble rock, probably of reef talus, characterized by
round fragments. The fragments, some of which are algal, are tan to light brown,

';B
2; 2;, 4 r41
-e~ ,7 ;s 4

Figure 26 Sawed face of core from Upper Cretceous 5034 40 in Amerada
No. 2 Cowles Magazine (Well 6), St. Lucie County.

BUREAU OF GEOLOGY

and are microcrystalline anhedral dolomite. A few of the fragments were
originally split in place and re-cemented. The fragments are incompletely
cemented together by medium crystalline dolomite, apparently a replacement of
calcite cement. The labyrinthine cavities between some fragments are lined with
drusy dolomite crystals. Porosity in the two specimens varies 5 to 15%, with
very high permeability.

DESCRIPTION OF CAVITIES

The geographical distribution of the Upper Cretaceous cavity zone is
shown on Fig. 29. The initial holes drilled at well locations 6 and 41 were
abandoned due to drilling difficulties caused by large caverns. All Upper
Cretaceous cavities and caverns have so far been found near the base of a massive
dolostone facies in the upper part of the system. Large cavities are encounted in
modern reefs near the base (MacLeish, 1973).

Figure 27 Scanning Electron Microphotograph of the same core shown as
in Figure 26, showing cementation by medium crystalline
dolomite.

SPECIAL INFORMATION NO. 20

In Well 6, four cavities were encountered from 5120 to 5294 near the base
of the massive dolostone section, the lowest and largest cavity measuring 17 feet
from floor to roof. The offset well, 1320 feet to the south, missed the cavern.

Well 41 was abandoned due to drilling difficulties by encountering a 50
foot cavern at 5270 feet. A second effort, 1% statute miles east, encountered a
42 foot cavern at 5210 feet. Considering the similar sub-sea elevation of these
two caverns and their similar thickness, it is likely that both are part of the same
system, if not the same cavern. This is the largest extent of a cavern system yet
recorded in South Florida.

In Well 52, 3 cavities, the largest 8 feet in height, were encountered at the
base of the massive dolostone facies.

Very little data are available from which to infer the lithology of the rock
surrounding these large Upper Cretaceous cavities as circulation returns cannot
be maintained and cuttings are not recovered. From drilling time above and

Figure 28 Same as Figure 27, enlarged X1500 showing faces of crystals and
intergranular porosity.

BUREAU OF GEOLOGY

10i 0 I y0 3 MILES

Figure 29 Isolith map of upper bank dolostone and cavity distribution in
Upper Cretaceous.

SPECIAL INFORMATION NO. 20

below the cavity, and from lithologic data on nearby or off-set wells, the host
rock is deducted to be light to dark brown, anhedral dolestone, the same
lithology which hosts the Cedar Keys and Eocene cavity zones.

PALEOCENE CAVITY ZONES

STRATIGRAPHIC SETTING

The normal Cedar Keys lithology consists of a complex of micro to fine
crystalline sucrosic dolostone interbedded with anhydrite. Along the Florida east
coast and into the Keys, this lithology changes into a tan to brown anhedral
dolostone with zones of porous euhedral dolostone (Fig. 30). This dolestone is
similar in lithology to the Upper Cretaceous massive dolostone and probably also
represents a back reef or bank deposit on the west side of the Florida Straits.

In Well 52 (Fig. 31), the electric log (no samples are available) indicates
that a chalky type carbonate intervenes between the massive Cedar Keys and
Upper Cretaceous dolostone. In Well 6, these dolostones are in contact.

DESCRIPTION OF CAVITIES

Two major cavities have been encountered in Paleocene bank dolostone.
Several drilling reports of "boulders" (Fig. 30) have also been reported. From
the incomplete data available, the Cedar Keys cavities appear to be scattered
within the massive dolostone.

In Well 55 a 50 foot cavernous zone was encountered in what on the
electric log appears to be massive dolostone between 3510 and 3560 feet; an
additional 15 foot cavern was encountered at a depth of 4285 4300 feet. No
samples were obtained at these intervals due to lost circulation. In Well 6, 2
two-foot caverns at a depth of 3481 83 and 4232 34 feet, were encountered
near the base of the massive dolostone. Well 44 was abandoned in the Cedar
Keys due to drilling difficulties associated with high transmissivities.

EOCENE HIGH TRANSMISSIVITY ZONES

STRATIGRAPHIC SETTING

Examination of the U. S. Gypsum Core Test (Well 30), shows that the
dolomite usually develops at a small distance beneath a peaty parting which is
often immediately underlain by a bed of limestone pebbles imbedded in a
micritic matrix; brown partings of unknown composition are frequently
associated with this "beach rock". Below the peat or "beach rock" may be a

BUREAU OF GEOLOGY

CONTOUR I
"C2 (2)"- C,
(00

loon rf'.

10 0 L "30 MILES

Figure 30 Isolith map of bank dolostone and high transmissivity
distribution in Cedar Keys Formation.

SPECIAL INFORMATION NO. 20 43

CEDAR
400

KEYS

FORMATION

5000

V) PINE KEY

GROUP

CAVITY __ 6000

Figure 31 Generalized Cedar Keys and Upper Cretaceous bank dolomite
sections based on Electric-log of Coastal No. 1 State (Well 52).

BUREAU OF GEOLOGY

limestone with dolomite crystal inclusions; below this is fine crystalline,
sucrosic, porous dolostone intermixed with non-porous anhedral dolostone of
the same crystal size. This zone grades down into a medium crystalline euhedral,
sucrosic or anhedral dolostone containing horizontally elongate vugs lined with
drusy masses of dolomite crystals. Porosity in this zone runs from 10 to 20%.
Beneath the dolomite is a thin zone exhibiting horizontal "partings" composed
of very thin layers of dolomite crystals, or a limestone with imbedded dolomite
crystals. Below this basal transition zone lies cream, chalky, skeletal limestone
with brown partings. The cuttings from several of the wells examined showed
similar features to these thin zones before losing circulation in the Eocene high
transmissivity zones.

CYCLE OF DOLOMITIZATION

Figure 32. Cycle of dolomitization.

SPECIAL INFORMATION NO. 20

From examination of several of these dolostone zones we infer that a
similar mode of development probably accounts for the larger cavity zones lower
in the section. In Well 54, a thick section of cream chalky limestone containing
masses of coarse dolomite crystals occupies the lower portion of the Eocene
where elsewhere the cavity zone occurs. From this instance, from literature
references, and from the association of similar lithology with the small cavity
zones in the U. S. Gypsum Core, it is inferred that the replacement of limestone
by dolomite, leading to the development of the large cavities took place in
chalky limestone, rather than in grainstone. A generalized cycle of
dolomitization based on their occurrence as observed in the U. S. Gypsum Core
(Well 30) is shown on Figure 32.

DISTRIBUTION OF CAVITIES

Areal distribution of the zones of high transmissivity is shown on Fig. 33,
34, and Fig. 35. In Eo-3, the cavities occur over virtually the entire study area
but are absent in the northwest part. On the Eo-2 map (Fig. 34), with two
exceptions, the zone of high transmissivity is confined to the north central part
of the area. The Eo-1 map (Fig. 35) shows two bands of development, one along
the trend of the Keys, and the other an arcuate trend across the northern half of
the map.

DESCRIPTION OF CAVITIES

Much of the Eocene zone of high transmissivity is composed of vugs in a
labyrinthine arrangement. Most of the larger cavities are less than one foot,
although, caverns of 63 (Fig. 34), 75 and 90 feet have been reported (Fig. 35).
The well penetrating the 90 foot cavern was abandoned, and the offset 500 feet
to the west missed the cavern.

Several zones of high transmissivity occur in a continuous core cut by U.
S. Gypsum Co. (part of Well 30) to a total depth of 2055 feet. One of the best
developed of these zones is described below. Several more of these zones are
illustrated in Figures 36, 37,38, 39 and 40.

DEPTH THICKNESS DESCRIPTION

Overbed
Limestone, cream, micrite; black very
fine grained inclusions; chalky
porosity.

BUREAU OF GEOLOGY

Figure 33 Occurrence of high transmissivity in Unit Eo-3.

Figure 33 Occurrence of high transmissivity in Unit Eo-3.

SPECIAL PUBLICATION NO. 20

S3 o a y ILES

Figure 34 Occurrence of high transmissivity in Unit Eo-2.

BUREAU OF GEOLOGY

OCCURRENCE OF IGH
TRU MiWMVITY

Sr- BOULDER
"u- aLOT C IaULATON

S2 (It)"- CAVERNS, QOUMTy.
(MAXIuu HEIGHT)

1 0 O 30 MILES

Figure 35 Occurrence of high transmissivity in Unit Eo-1.

SPECIAL PUBLICATION NO. 20

IrTU i

Ar

AJ

Figure 36 Photograph of upper dolomite zone at 2030 feet in U. S.
Gypsum Core (Well 30) showing peaty partings, "beach rock"
rubble, and sucrosic dolomite zones.

BUREAU OF GEOLOGY

j &a

4s~.

Figure 37 Photograph of the top of the dolomite zone at 2046 feet in U. S.
Gypsum Core (Well 30) showing peaty partings and limestone in
irregular contact with incompletely dolomitized limestone.

-" "

. : .; ;-

SPECIAL PUBLICATION NO. 20

Figure 38 Photograph of the basal contact of the dolomite zone at 204612
feet in the U. S. Gypsum Core (Well 30) showing dolomite
grading into incompletely dolomitized limestone, underlain by
peaty partings in limestone with dolomite crystal inclusive.

;~jpa8;~.' L

;,:~ ....E.
J-

;: ;;b.r Ir

BUREAU OF GEOLOGY

52

DEPTH
2042

Figure 39 Photograph of the core at 2050 feet in the U. S. Gypsum Core
(Well 30) showing preferred horizontal orientation of vug
porosity in dolomite zone.

THICKNESS DESCRIPTION

0.5" Sloping contact with lithology below
characterized peaty parting.

0.1" Limestone, tan; coarse grained, white
flat pebbles and brown partings.

0.6" Dolostone, tan, medium crystalline

1.5" Sloping contact

V,
#'

'4~
~~i

SPECIAL PUBLICATION NO. 20

DESCRIPTION

Dolostone, dark brown, anhedral;
limestone, white chalky, up to 1/2
inch in size; shape blocky or flat,
occasional vugs up to 0.2"

Dolostone, tan very fine crystalline
euhedral; and pinepoint vug porosity.

Dolostone, brown, anhedral, very fine
crystalline; 0.1" vugs.

3.0"

4.5"

1.5"

4.3"

tan, fine crystalline,
10% intercrystalline

CAVITY

' DOLOMITE FINE CRYSTALLINE
.F'Ej DRAL PINPOINT POROSITY

DOLOMITE FINE CRYSTALLINE
SUCROSIC, INTERCRYSTALLINE
PAIOSITY

. -<1

Figure 40 Sawed face of same core in Figure 39.

DEPTH

THICKNESS

Dolostone,
euhedral;
porosity.

WHITE ANHYDRITE
(ol white inclusions)

CAVITY
cnvl~

BUREAU OF GEOLOGY

0.3" Limestone, cream, micrite, chalky
with partings and/or crusts of
dolomite crystals; peaty parting, lime-
stone, cream, micritic, chalky; streaks
of dolomite, very fine crystalline.
2044
0.1" Sloping contact
Underbed
Limestone, cream, micrite, chalky;
brown parting.

Some 180 stereo photographs were taken by the Sun Oil Company from
1300 to 2616 feet in their Red Cattle 32-2, Hendry County, Florida. Data on
the size, shape, and vertical distribution of the cavities in the zone of high
transmissivity, generally occurring from 2000 to 3200 feet in that area are given
in Appendix 2.

Although it was not possible to identify openings less than 1 inch in size,
several conclusions can be made concerning the larger cavities.

1. There is a marked preference of horizontal distribution and shape.
Overwhelmingly the most common are cavities with a 2:1 horizontal
over vertical dimension ratio. Cavities with round cross-section are
rare.
2. Cavities with a vertical dimension of 3 to 4 inches are the most
common, cavities over 5 inches were uncommon; those over 12
inches were rare.
3. Although isolated cavities were observed, most tend to occur in
horizontal zones some 1 to 2 feet thick.
4. Cavities with a horizontal dimension larger than the hole size were
frequently encountered. They ranged from 3 6 inches high, and
occurred not only singly, but also in multiples, forming a "pancake
stack" of cavities with only inches of dense dolostone separating
them.
5. A number of "tunnels" were observed. These are equidimensional
cavities which are found on opposite sides of the bore hole, and are
construed to be the tunnels which the bore hole apparently cut.
Cavities identified as such are isolated; in large groups of cavities this
type relationship would be difficult to establish.

SPECIAL PUBLICATION NO. 20

6. An observed odd-shaped cavity cross section included 2 isosceles
triangles and a square.
7. Large caverns are extremely rare. In this well only one was
encountered, some 90 feet in height. It is the next largest yet
recorded in south Florida (largest 100 feet high, 6 miles west).
8. Vertical cavities are very rare.
9. Vertical fractures were not seen.
10. Several paired scratches on the walls probably from withdrawing the
drill rod can be misinterpreted as vertical fractures.

HYPOTHESES OF ORIGIN OF CAVITIES AND
DOLOMITIZATION

As we have as yet insufficient data to back up our ideas on this subject,
and since the origin of the cavities and solutional interstices is not of primary
importance in this descriptive report, we are not proposing a hypothesis of our
own at this time. As all cavity and solutional interstices occur inr dolostone, a
review of the literature on the process of dolomitization is in order.

DOLOMITIZATION

a. Modern:
Observation of field conditions under which modern dolomite is forming,
as well as laboratory experiments, have shown that certain conditions are
necessary for the replacement of calcite by dolomite:

1. High salinity (200,000 PPM ? ?). An arid climate was the only
mechanism so far reported which produced salinities of the
necessary concentration.
2. High Mg-Ca ratio. Field observations showed that this condition was
produced by the removal of calcium, either by organic processes or
by precipitation of CaSO4, thus leaving behind a large surplus of
magnesium.
3. High pH (9 or more) was observed in all occurrences of
marine-associated dolomite.
4. Tidal flat dolomites consist of crusts of dolomite rhombs.

b. Ancient:

Some field observations concerning dolomitization in ancient rocks which

BUREAU OF GEOLOGY

are applicable to the present problem follow:

1. Organic activity, principally bacteria and algae, may either
precipitate dolomite, or cause conditions to become favorable for
dolomitization principally by controlling the pH in shallow lagoons.
Some organisms are much more susceptible to dolomitization than
others. Among the most susceptible are the calcareous algae.
2. Dolomitization is frequently associated with disconformities; all
known Recent occurrences have been so associated.
3. Fine grain, high-porosity, low-permeability calcium carbonate
sediments are the preferred sites of dolomite replacement. It is
suggested in this connection that replacement of grainstone, when it
occurs at all, probably occurs during lithification when the
formation waters are concentrated and driven out by compaction.
4. Several field observations concluded that porosity in dolostone
resulted from the solution of limestone from a dolomite rhomb
matrix, not from the process of dolomitization itself.

HYPOTHESES OF CAVITY ORIGIN

Dolomitization is critical to the formation of the cavities, as all cavities
occur in dolostone. All hypotheses stand or fall on the time of dolomitization.
So far, there is no evidence to conclusively prove when this took place.

Previously expressed hypotheses include those of Vernon (1947, 1951,
1971) and Kohout (1965), and Hanshaw, Back & Dieke (1971).

Vernon (1970) proposed a geochemical reaction that follows the mixing of
two bodies of water that contrast in concentration of salts. The interface is the
locus of dolomitization and of an intensified solution and removal of solids.

Kohout proposes a convection current, generated by geothermal heating of
sea water freshly intruded into the high transmissivity zone from the rock
outcroppings in the Straits of Florida at the east, south, and west sides of the
Floridian Plateau. Dolomitizing magnesium-rich water is thus continuously
circulated into the aquifer to provide the magnesium for continuous
dolomitization.

A geochemical hypothesis for dolomitization by ground water was offered
by Hanshaw, Back, and Deike (1971). Their study was based on chemistry of the
Floridan ground water and the mineralogic composition of the artesian aquifer.
They observed that there was a systematic change in the magnesium to calcium
ratio from 0.5 in the potable water to 1 from the recharge area down-gradient

SPECIAL PUBLICATION NO. 20

into the deeper part of the aquifer system. They examined stable carbon isotope
composition of calcite-dolomite and found that the calcite 6 C13 composition is
always that of normal marine limestone; however, the 6 C13 of the associated
dolomite was not formed under marine conditions but was formed under the
effect of ground water, perhaps saline.

From our incomplete data in this study, we observed that the base and top
of cavity zones in cores are usually bounded by peaty partings, or other
impediments to vertical migration of fluids. The dolomitizing fluids then were
forced to spread laterally, creating the horizontally oriented cavities and zones
of cavities.

EVALUATION OF THE ZONES OF HIGH
TRANSMISSIVITY FOR LIQUID STORAGE

The principal concern in the use of the subsurface for waste storage is the
possibility of seepage into near-surface or deeper artesian aquifers used for
drinking water. Data from this study can help allay these fears as follow:

1. Over the study area, several hundred feet of Miocene shales or plastic
clays provide an effective aquiclude, in the unlikely case of the fluids
reaching that point.
2. Although aquicludes within the Eocene are usually thin and few in
number, thick Eocene limestones of low permeability overlie the
zone of high transmissivity. These beds, if they transmit water at all,
would act as filter beds, which chemically or physically should
purify the transmitted water on its upward journey.
3. Such aquicludes as are present in the Eocene are of limited
horizontal extent. (See Fig. 41, 42, and 43). When present, they
would divert ascending non-acidic fluids into a tortuous path several
times as long as that directly to the surface. This longer path would
allow even more time for the water to be purified.
4. From our study, there is no known evidence, nor any reason to
suspect the presence of vertical connections between the Upper
Cretaceous, Paleocene, and Eocene cavity zones. All evidence shows
that they are separate, therefore, the older two should make
excellent storage reservoirs, either for fresh water or well-treated
nonacidic effluents.
5. From studying the photographs of the Eocene zone in the Sun Red
Cattle 32-2, it can be observed that horizontal permeability is
overwhelmingly dominant over vertical permeability. Vertical
permeability is rare through the dense dolostone separating

BUREAU OF GEOLOGY

horizontal cavity zones. The vertical connections which do exist
appear to be very short.
6. Large caverns, if commonly found, could be used for injection
purposes.

RECOMMENDATIONS

1. In order to reduce the chances of surface contamination to a
minimum, the fluids should be injected into the base of the high
transmissibity zone, (not at the top, as is presently done), to place
the fluids farther from the surface.
2. Whenever possible, in completing storage wells, stereophotographs
should be taken of the high transmissivity zone in order to
determine distribution and size of the cavities and the amount of
vertical connection, if any. Data obtained from the photographs will
throw light on the presence or absence of fractures and small-scale
faults in the area, which could not otherwise be detected.
Stereophotographs will also provide a permanent, non-interpretive
visual record of the well.
3. Use of the Cedar Keys and Upper Cretaceous cavity zones along the
highly populated east coast of Florida for injection of industrial
waste would be acceptable. Being deeper than the Eocene, these
zones would be even less likely to ascend to shallower depths.

SPECIAL PUBLICATION NO. 20

*44
10

I0o o 0 o 3yMILES

Figure 41 Map showing ratio of feet of aquifer per foot of aquitard and
thickness of aquiclude in Unit Eo-3.

BUREAU OF GEOLOGY

1o T y a30 MILES

Figure 42 Map showing ratio of feet of aquifer per foot of aquitard and
thickness of aquiclude in Unit Eo-2.

SPECIAL PUBLICATION NO. 20 61

.5'

L INE RV l Iy

. **u .... ..... 0

o 10- :o *oo*:o '""."".""" '..
.. ..: ;. r. . ...... .*" ,

.....3 ..... ..........-:.,:.:
. . .. .. ...g ...

*.. ... *. . .. . .

Figure 43 Map showing ratio of feet of aquifer per foot of aquitard and
thickness of aquiclude in Unit Efo-1.

10 0

62 BUREAU OF GEOLOGY

SPECIAL PUBLICATION NO. 20

BIBLIOGRAPHY

Adams, N. E.
1960 (and Rhodes, M. C.) Dolomitization by seepage refluxion: Am. Assoc.
Petroleum Geologists BulL, v. 44, p. 1912-20.

Antoine, J. W.
(see Bryant, W. R.)

Applin, E. R.
(see Applin, P. L.)

Applin, P. L.
1944 (and Applin, E. R.) Regional subsurface stratigraphy and structure of Florida
and southern Georgia: Am. Assoc. Petroleum Geologists Bull, v. 28, no. 12, p.
1673 1753.

Atwood, D. K.
1970 (and Bubb, J. N.) Distribution of dolomite in a tidal flat environment,
Sugarloaf Key, Florida: Jour. Geology.

Back, W.
(see Hanshaw, B. B.)

Banks, J. E.
(see Puri, H. S.)

Brown, J. K., Jr.
(see Bryant, W. R.)

Bryant, W. R.
1969 (and Meyerhoff, A. A., Brown, N. K., Jr., Furrer, M. A., Pyle, W. E. &
Antoine, J. W.) Escarpments, Reef Trends, & Diapiric Structures, Eastern
Gulf ofMexico: Am. Assoc. Petroleum Geologists Bull., v. 53, p. 2506 2542.

Bubb, J. N.
(see Atwood, D. K.)

Chen, C. C.
1965 The regional lithostratagraphic analysis of Paleocene and Eocene rocks of
Florida: Fla. Geol. Sur. Bull. 45, p. 105.

Curtis, R.
1963 (and Evans, G., Kinsmann, D. J. & Shearman, D. J.) Association of dolomite
and anhydrite in the Recent sediments of the Persian Gulf: Nature, v. 197, p.
679-80.

Deffeyes, K. S.
1965 (and Lucia, F. J. & Weyl, P. K.) Dolomitization of Recent and
Plio-Pleistocene sediments by marine evaporate waters on Bonaire,
Netherlands Antiles: in L. C. Pray and R. C. Murray Eds., Dolomitization and

BUREAU OF GEOLOGY

limestone diagenesis: Soc. Econ. Paleontologists and Mineralogists Spec. Publ.
13, p. 71 -81.

Deike, R. G.
(see Hanshaw, B. B.)

Emery, K. O
(see Uchupi, E.)

Evans, G.
(see Curtis, R.)

Faulkner, G. L.
(see Kaufman, M. I. and Puri, H. S.)

Furrer, M. A.
(see Bryant, W. R.)

Garcia Bengochea, J. I.
(see also Vernon, R. O.)
1969 (and Vernon, R. O.) Deep-well disposal of wastewater in saline aquifers of
South Florida: Paper presented at the Am. Geophy. Union Meeting,
Washington, D. C., April.
1973 (Sproul, C. R., Vernon, R. 0. and Woodard, H. J.) Artificial Recharge of
Treated Waste Waters and Rainfall Runoff into Deep Saline Aquifers of
Peninsula of Florida: in Underground Waste Management and Artificial
Recharge: 2nd International Symposium, V. 1, p. 505 525. (New Orleans,
La. Sept. 26 30, 1973)

Ginsburg, R. N.
(see Shinn, E. A.)

Goolsby, D. A.
(see Kaufman, M. I.)
1972 Geochemical effects and movement of injected industrial waste in a limestone
aquifer: in T. D. Cook, ed., Underground waste management and
environmental implications: Am. Assoc. Petroleum Geologists Mem. 18, p.
355 -368.

Hanshaw, B. B.
1965 (and Back, W. & Rubin, M.) Radiocarbon determinations for estimating
ground-water flow velocities in Central Florida: Science V. 148, p. 494 495.
1971 (and Back, W. & Deike, R. G.) A geochemical hypothesis for dolomitization
by ground water: Econ. Geol. v. 66, p. 710 723.

Harris, L. D.
1971 A lower Paleozoic paleoaquifer: The Kingsport Formation and mascot
dolomite of Tennessee and Southwest Virginia: Econ. Geol. V. 66, p. 735 -
43.

SPECIAL INFORMATION NO. 20

Henry, H. R.
1972 (and Hilleke, J. B.) Explanation of multiphase fluid flow in a saline aquifer
system affected by geothermal heating: University of Alabama Bur. Engr.
Res. Report 118 p.
1972 (and Kohout, F. A.) Circulation Pattern of Saline Groundwater affected by
geothermal heating-as related to waste disposal: Symposium on Under-
ground Waste Management and Environmental Implications, Am. Assoc.
Petroleum Geologists Memoir 18, p. 202 221.

Hsu, J. K.
1963 Solubility of dolomite and composition of Florida ground waters: Jour.
Hydrology, v. 1, p. 228 310.

Hunn, J. D.
(see Wilson, W. E.)

Hurley, R. J.
(see Malloy, R. J.)

Killing, L. V.
1965 (and Wells, A. J., & Taylor, J. C. M.) Penecontemporary dolomite in the
Persian Gulf in L. C. Pray and R. C. Murray Eds. Dolomitization and
limestone diagenesis: Soc. Econ. Paleontologists and Mineralogists Spec. Pub.
13 p. 89- 111.

Kaufman, M. I.
1973 Subsurface wastewater injection, Florida: Am. Soc. Civil Engineers Proc.,
Jour. Irrigation and Drainage Div., v. 99, no. IR1, p. 53 70.
1973 (Goolsby, Donald A. & Faulkner, Glen L.) Injection of Acidic Industrial
Waste into a Saline Carbonate Aquifer: Geochemical Aspects: in Underground
Waste Management and Artificial Recharge: 2nd International Symposium, v.
1., p. 526 551. (New Orleans, La., Sept. 26 30, 1973).

Kinsmann, D. J.
(see Curtis, R.)

Kohout, F. A.
1965 A Hypothesis concerning cyclic flow of salt water related to geothermal
heating in the Floridan Aquifer: New York Aca. of Sci. Trans. 1965 p. 249 -
271.
1967 Ground-water flow and the geothermal regime of the Floridan plateau: Trans.
Gulf Coast Assoc. Geological Societies, v. 17, p. 339 354.

Levin, H. L.
1957 Micropaleontology of the Oldsmar limestone (Eocene) of Flori-
da: Micropaleontology, v. 3, no. 2, p. 137 150.

Lloyd, R. N.

(see Shinn, E. A.)

BUREAU OF GEOLOGY

Lucia, F. J.
(see Deffeyes, K. S.)

MacLeish, K.
1973 Exploring Australia's Coral Jungles: National Geographic, v. 142, p. 743 93.

Malloy, R. J.
1970 (and Hurley, R. J.) Geomorphology and geologic structure: Straits of
Florida: Geol. Soc. Am. Bull. v. 81, p. 1947 72.

Meyer, F. W.
1970 Some aspects of saline artesian water as a supplementary supply in southern
Florida: U. S. Geol. Sur. Open File report.

Meyerhoff, A. A.
(See also Bryant, W. R.)
1973 Bahamas Salient of North America: tectonic-framework, stratigraphy and
petroleum potential: Am. Assoc. Petroleum Geologists Bull., (in press).

Puri, H. S.
1959 (and Banks, J. E.) Structural features of the Sunniland oil field, Collier
County, Florida: Gulf Coast Assn. Geological Soc. Trans., v. 19, p. 121 130.
1973 (Faulkner, G. L. and Winston, G. O.) Hydrogeology of subsurface
Liquid-Waste Storage in Florida: in Underground Waste Management and
Artificial Recharge: 2nd International Symposium, v. 2, p. 825 850. (New
Orleans, La. Sept. 26 30, 1973).

Pyle, T. E.
(see Bryant, W. R.)

Rhodes, M. C.
(see Adams, J. E.)

Rosenshein, J. S.
(see Wilson, W. E.)

Rubin, W.
(see Hanshaw, B.B.)

Shearman, D. J.
(see Curtis, R.)
Shinn, E. A.
1964 Recent dolomite, Sugarloaf Key, Florida: in R. N. Ginsburg, Composition,
South Florida carbonate sediments Guidebook for fieldtrip No. 1 Geol. Soc.
Am. Ann. Mtg. Miami Beach, Nov., 1964, p. 24 33.
1965 (and Ginsburg, R. N. and Lloyd, R. M.) Recent supratidal dolomite from
Andros Island, Bahamas: in L. C. Pray and R. C. Murray Eds. Dolomitization
and limestone diagenesis: Soc. Econ. Paleontologists and Mineralogists Spec.
Pub. 13, p. 112 -123.
1968 Selective dolomitization of Recent sedimentary structures: Jour. Petrology, v.
35, p. 612 66.

SPECIAL PUBLICATION NO. 20

Sproul, C. R.
(see Garcia Bengochea, J. I.)

Taylor, J. C. M.
(see Illing, L. V.)

Uchupi, E.
1967 Bathymetry of the Gulf of Mexico: Gulf Coast Assoc. Geol. Socs., Trans., v.
17, p. 161-172.
1967 (and Emery, K. O.) Structure of Continental margin off Atlantic coast of
United States: Bull. Am. Assoc. Petroleum Geologists, v. 51, p. 223 34.

Vernon, R. O.
(see also Garcia Bengochea, J. I.)
1947 Tertiary formations cropping out in Citrus and Levy Counties: in
Southeastern Geological Society (Guidebook) 5th Field Trip, West Central
Florida, Dec. 5 6, 1947, p. 35 54, (1947).
1951 Geology of Citrus and Levy counties, Florida: Florida Geological Survey,
Bull. 33, 256 pp.
1967 (and Garcia- Bengochea, J. I.) Deep Well Injection of Industrial Wastes in
South Florida: Petro. Coun., November 1, 1967, p. 35 44, (1947).
1970 The beneficial uses of zones of high transmissivities in the Florida subsurface
for water storage and waste disposal: Fla. Bur. Geol. Inf. Cir. 70, 39 p.

Wells, A. J.
1962 Recent dolomite in the Persian Gulf: Nature v. 194, p. 274 75.

Wells, A. J.
(see Illing, L. V.)

Weyl, P. K.
(see Deffeyes, K. S.)

Wilson, W. E.
1973 (Rosenshein, J. S. and Hunn, J. D.) Hydrologic Evaluation ofIndustrial-Waste
Injection at Mulberry, Florida: inUnderground Waste Management and
Artificial Recharge: 2nd Symposium v. 1, p. 552 564. (New Orleans, La.,
Sept. 26- 30, 1973).

Winston, G. O.
(see also Puri, H. S.)
1971 The Dollar Bay Formation of Lower Cretaceous (Fredricksburg) age in South
Florida: Its Stratigraphy and Petroleum Possibilities: Fla. Bur. Geol., Spec.
Pub. 15, 99 p.
1971 Regional Structure, Stratigraphy, and Oil Possibilities of the South Florida
Basin: Gulf Coast Assoc. Geol. Socs., Trans., v. 21, p. 15 29.
1972 Oil Occurrence and Lower Cretaceous Carbonate Evaporite Cyclothems in
South Florida: Am. Assoc. Petroleum Geologists Bull., v. 56, p. 158 160.

Woodard, H. J.
(see Garcia Bengochea, J. I.)

68 BUREAU OF GEOLOGY

SPECIAL PUBLICATION NO. 20

APPENDICES

BUREAU OF GEOLOGY

APPENDIX 1 ELECTRON SCANNING MICROPHOTOGRAPHS OF
TYPICAL CARBONATE LITHOLOGIES

SPECIAL PUBLICATION NO. 20

Figure 44 Scanning Electron Microphotograph of Skeletal limestone from
Unit Eo-2, 100% coarse grained (depth 2435 -50 ft.), Gulf-Cal.
Block 46 (Well 46) Monroe County (X100).

Figure 45 Same enlarged X2100 to show calcite crystals.

2 BUREAU OF GEOLOGY

711''-|;

S. lt I ?"5 B *.-i

Scanning Electron Microphotograph of Skeletal limestone from
Tampa Stage (depth 1160 70 ft), Co stal No. 1 State (Well 52)
Monroe County (X100).

Figure 47 Same enlarged X1500 to show calcite crystals.

Figure 46

SPECIAL PUBLICATION NO. 20

Figure 48 Scanning Electron Microphotograph of micritic limestone from
Unit Eo-2 (depth 2650 60), Peninula No. 1 Cory (Well 54)
Monroe County (X100).

Figure 49 Same enlarged X2000 to show calcite crystals.

BUREAU OF GEOLOGY

Figure 50 Scanning Electron Microphotograph of lithographic dolostone
from Unit Eo-3 (depth 3540 50 ft), Coastal No. 1 State (Well
52) Monroe County (X100).

Figure 51 Same enlarged X1500 to show dolomite crystals.

SPECIAL PUBLICATION NO. 20

ow Y 4'
EE
";takr 1 t F1

Figure 52 Scanning Electron Microphotograph of dolostone, micro-
crystalline, euhedral from Unit Eo-1 (depth 1470 80 ft.),
Coastal No. 1 State (Well 52) Monroe County (X100).

Figure 53 Same enlarged X1000 to show faces of dolomite crystals.

1&95 &~Z1p~

BUREAU OF GEOLOGY

Scanning Electron Microphotograph of dolomite, fine
crystalline, euhedral, Tampa Stage (depth 1035 ft.), Coastal No.
1 State Monroe County (X100).

Figure 55 Same enlarged X1000 to show faces of dolomite crystals.

Figure 54

41~ k"crr.
*L *
(C~ ~u

1 1r"1

C~c~
r
r
Cr~r;~ r r+

SPECIAL PUBLICATION NO. 20

V

Figure 56 Scanning Electron Microphotograph of dolomite, medium
crystal sucrosic, euhedral, 20% vugs and intragranular, porosity,
Eo-3 (depth 3440 3500 ft.), Mobil No. 1 Babcock Ranch (Well
10), Charlotte County (X100).

Figure 57 Same enlarged X530 to show faces of dolomite crystals.

-~C~
.*
r-
'-iE

mom ,,

^~ V r4

BUREAU OF GEOLOGY

Figure 58 Scanning Electron Microphotograph of dolomite, very finely
crystalline, anhedral, Upper Cretaceous, bank dolomite (depth
5210- 20 ft.) Gulf-Cal. Block 46 (Well 46), Monroe County
(X100).

I 7.:. ,' "Ja .

Figure 59 Same enlarged X1500 to show anhedral crystal arrangement

,I,
a `:I

SPECIAL INFORMATION NO. 20

APPENDIX 2 DESCRIPTION OF CAVITIES IN SUN 32-2 RED
CATTLE STEREOPHOTOGRAPHS

80 SPECIAL PUBLICATION NO. 20

.. ..- -.s.... .t

Fgr6 Pht rp o220otlvinS 322 eCa',t le
'.;U 4. ?..a.:;?. "".-. *-. "'-.,'.e.,.

''. S t,.-t "- '

"'9554 --

Figure 60 Photograph of 2230 foot level in Sun 32-2 Red Cattle.

Figure 61 Photograph of 2258 foot level in Sun 32-2 Red Cattle.

BUREAU OF GEOLOGY

Figure 62 Photograph of 2272 foot level in Sun 32-2 Red Cattle.

Figure 63 Photograph of 2308 foot level in Sun 32-2 Red Cattle.

SPECIAL PUBLICATION NO. 20

#s-: I .: ... .: .: .
< "
. .n ; .

.: 1... : ... ... : ., :. ? .' : ,O .] . .
.B .." i:. .. .z
q r ".1 ... ":" b:"s~ ~:: ; "- i. ,": : : ".

Y.> A ,''`:i -:;: r.r ., .~,

F.' igur. 64 Phtgrp of" 2376 foot lee .in Su 32 2 Red ate:
: ':;. '; ;.'" 5. : i. 's3"' '- :; '~:' ""
ci ..' . .. :: - ... ..~i
Figure~ ~ ~ ~~~~~~ 64Phtorahof23 oo evl n un3-2 Re tte

4''

Figure 65 Photograph of 2436 foot level in Sun 32-2 Red Cattle.

, s o:.a~;-~
: ~cr.~.~bC'

. W.'
: '. '

"~~ ;:

BUREAU OF GEOLOGY

Figure 66 Photograph of 2496 foot level in Sun 32-2 Red Cattle.

LX7ir

84 BUREAU OF GEOLOGY

APPENDIX 2

Description of Cavities in Sun 32 2 Red Cattle stereo-photographs

SIZE CLASSIFICATION FOR USE WITH THIS DESCRIPTION

vug Largest dimension 3" or less, round unless otherwise
specified

cavity Largest dimension less than 2 feet, shape variable,
usually discoid more than 3" high

cavern Smallest dimension more than 2 feet

SHAPE CLASSIFICATION

tunnel 2 cavities, essentially round, where are so oriented
that they probably extend across hole

pancake cavities A stack of flat cavities, usually larger than full
hole size

SPECIAL INFORMATION NO. 20 85

APPENDIX

Depth Shape of Hole Description

1343 round murky

1344 round murky

1346 round murky

1350 round enlarged open hole below casing, murky

1352 murky
1354 oval no visible porosity, murky

1356 oval murky

1358 oval appears to have two small vugs a fraction of an
inch in diameter, murky

1360 oval no visible porosity, murky

1362 oval no visible porosity, murky

1364 oval no visible porosity, murky

1366 2 lobe hole shape intergrading between above & below,
murky

1368 2 lobe smooth, murky

1370 2 lobe smooth, murky

1372 2 lobe smooth, murky (2 poss. '/" vugs)

1374 2 lobe smooth, murky

1378 2 lobe smooth, murky

1380 3 lobe murky

1400 3 lobe 6" cavity (at least 1/2 hole)

1600 oval took marks

1800 oval probably becoming dolomitic, with irregularities in
smooth wall looking like small washouts.

1900 oval 6" hole cavity at bottom?, murky

2000 oval large 6" cavities, labyrinthine, occupies lower of
hole, also numerous vugs

86

Depth

2100

2200

2202

2204

2206

2208

2210

2212

2214

2216

2218

5 2" vugs in smooth wall

poss 1 x 1/2" vug

tool marked wall w/1 x 1" vug

tool marks, banded

tool marks, banded

5 4" vugs, 2 8" cavities; at bottom, 8" full hole
cavity

4" 1/ hole cavity, one large 6" cavity has "ledge"
hanging out into hole about 2"

5" cavity, banded

4 3 x 3" vugs, otherwise non-porous; banded

dense, no visible porosity

dense, no visible porosity

dense, no visible porosity

BUREAU OF GEOLOGY

Shape of Hole Description

egg tool marks, 2 bands of black (peat?)

egg no visible porosity

egg no visible porosity

egg 2" round vugs

egg tool marks

egg tool marks

4 lobe 2 1" bands (peat ?)

4 lobe 2 1" bands (peat ?)

4 lobe full hole cavity 2 3" high

4 lobe 8 irregular shaped vugs 2 4" max. dia.

4 lobe 20 vugs, most in a closely packed almost
labyrinthine system, leading into large cavity, 1/3
hole, 8" high

2220

2222

2224

2226

2228

2230 (Fig. 60)

4 lobe

oval

oval

oval

oval

oval

2234

2236

2238

2240

2242

5 lobe

5 lobe

egg

egg

egg

SPECIAL

Shape of Hole

egg

2 lobe

Depth

2244

2246

2250

2252

2286 oval

2 lobe

2 lobe

2 lobe

2 lobe

2 lobe

2 lobe

round

round

4 lobe

round

round

round

round

round

oval

PUBLICATION NO. 20 87

Description

dense, no visible porosity

milled-out ledge, cavity 8 x 16", dozens 1-2" vugs,
banded

dense, banded

1 12 x 4" cavity across from 8 x 8" (tunnel ?) 7 2
x 2" vugs, banded

3 4 x 8" cavities, banded

1 10 x 4", 2 6 x 6" cavities; 5 3 x 3" vugs; several
cavities seem to be part of a labyrinthine system

1 8 x 8" tunnel, 3 stack 4" pancake, '/2 & full
hole; probably labyrinthine numerous 2 x 5"
cavities

1 3/4 hole 3" cavity; r 1 x 3" vugs; 2 diagonal 1 x
6" cavities; 1 8 x 8" tunnel; banded

2 1 x 12", 1 1 x 8", 2 1 x 4" cavities; 1 vertical
cavity 2 x 8" intersecting a 1 x 12" cavity

4 2 x 2", 1 1 x 3" vugs, banded

labyrinthine vug zone on % wall, 12" thick; 2 10"
tunnels apparently cross in hole, numerous vugs

12" cavity zone w/3 x 10" irregular roofed cavity;
1 3 x 3" vugs probably tunnel back and re-enter
hole; rest of hole no visible porosity

10 1" vugs, 1 3 x 5" cavity, bubbles

5 x 10" cavity; triangular cavity 5"; 4 1 x 3" vugs;
bubbles in water

15 1" vugs in 2 zones; triangular cavity in upper
part of hole as above

bubbles

no visible porosity, reduced hole diameter due to
drilling, banded, bubbles in water

4 2 x 6" cavities, tool marks, bubbles in water

2256

2258 (Fig. 61)

2262

2264

2268

2270

2272 (Fig. 62)

2274

2276

2278

2280

2282

2284

88

Depth

2288

2292

2294

2294

2298

2300

BUREAU OF GEOLOGY

Shape of Hole Description

oval 2 2 x 4" cavities, took marks, cavity 4 x 4",
irregular vertical solution channel

oval same vertical channel as above, 2" horizontal vug
band, bubbles in water

oval occasional irregular vugs

oval occasional vugs

oval occasional small vugs, banded

oval 1 diagonal cavity 1 x 8"; 1 vertical cavity 1 x 6",
banded

1 10 x 10" cavity with roof slab loose; floor
covered with cuttings and stick! 3 2 x 2" vugs

sucrosic zone

3 1 x 4" cavities, banded

3" zone w/3 1 x 4" cavities, banded

2 stack pancake, 1 full hole 1 3/4 occupied hole; 3
x 3" vugs, occasional small vugs

2 cavity zones, 6" thick; 2 1 x 6" 1 4 x 4" cavities,
2 3 x 3" vugs, 14" cavity half hole w/roof debris
overhanging hole; 1 8 x 8" tunnel

1 8 x 8" cavity, 4 3 x 3" vugs

2 cavity zones 6" thick 6" apart labyrinthine,
w/max. size cavities 4 x 10" many 3 x 3" vugs,
irregular horizontal cavities; bubbles in water

1 3" vug, banded

2 labyrinthine cavity zones, both /2 hole; 3 3 x 3"
vugs, 1 4 x 4" cavity, 1 6 x 6" cavity, 3 4 x 4"
cavities

3 6 x 6", 3 4 x 4" cavities in 12" zone

more than 20 3 x 3" vugs

1 6 x 6" cavity, 1 3 x 3" vug

2302

2304

2306

2308 (Fig. 63)

2312

2330

2332

2336

2338

2344

oval

oval

3 lobe

Depth

2346

2350

2352

2354

2356

2362

2364

2366

2368

SPECIAL

Shape of Hole

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

3 lobe

INFORMATION NO. 20 8!

Description

8" cavity zone w/t 4 x 4" cavities, 6 3 x 3" vugs in
rows, banded

banded carbonate w/cavity zone in one of the
bans w/4 x 10" cavities

continuation of banding w/2 more cavity zones
separated by a band

1 2 x 6", 1 2 x 4" cavity, banded

4" band of " vugs or sucrosic porosity

8 2 x 2" vugs, tool marks

cavity zone 12" thick; 1 4" full hole cavity 3 4 x
4" cavities

3" soft zone small vugs or sucrosic porosity;
mottled dark & light at bottom picture banded,
mottled

1 4 x 4" cavity, all else dense, banded

no visible porosity with soft (sucrosic) zone; milled
out ledge

no visible porosity

1 3 x 5" cavity, 2 3 x 3" vugs

1 3 x 6" full hole cavity

1 6 x 15" tunnel, 1 8 x 8" tunnel & 6 x 6" cavity
near bottom picture

1 4 x 8", 1 4 x 4" cavity, occasional vugs

1 tunnel 10 x 10" becoming 6 x 6"; 1 5 x 5"
cavity

3 stack pancake 'A hole, 6", 4", 4"

1 3 x 6" cavity; 2 3 x 3", 2 2 x 2" vugs

murky, numerous vugs

occasional vugs

no visible porosity, took marks

2370

2372

2374

2376 (Fig. 64)

2382

2384

2390

2394

2396

2398

2400

MILLISECOND	CLASS.METHOD	MESSAGE
0	sobekcm_page_globals.constructor
0	sobekcm_page_globals.constructor	Application State validated or built
0	sobekcm_database.verify_item_lookup_object
0	sobekcm_page_globals.constructor	Navigation Object created from URI query string
0	sobekcm_database.verify_item_lookup_object
0	sobekcm_page_globals.display_item	Retrieving item or group information
0	sobekcm_page_globals.get_entire_collection_hierarchy	Retrieving hierarchy information
0	sobekcm_assistant.get_entire_collection_hierarchy
0	cached_data_manager.retrieve_item_aggregation
0	cached_data_manager.retrieve_item_aggregation	Found item aggregation on local cache
0	item_aggregation_builder.get_item_aggregation	Found 'all' item aggregation in cache
0	system.web.ui.page.page_load (ufdc.page_load)
0	sobekcm_page_globals.constructor.on_page_load
0	html_echo_mainwriter.add_style_references	Adding style references to HTML
0	html_echo_mainwriter.add_text_to_page	Reading the text from the file and echoing back to the output stream
109	html_echo_mainwriter.add_text_to_page	Finished reading and writing the file

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