Sequence Stratigraphy of the Arcadia Formation, Southeast

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SEQUENCE STRATIGRAPHY OF THE ARCADIA FORMATION, SOUTHEAST

FLORIDA: AN INTEGRATED APPROACH

Caroline M. Wright

A Thesis Submitted to the Faculty of

the Charles E. Schmidt College of Science

in Partial Fulfillment of the Requirements for the Degree of

Master of Science

Florida Atlantic University

Boca Raton, Florida

August 2014

ACKNOWLEDGEMENTS

I would like to thank my committee and the professionals at the USGS for their support and patience. Dr. Kevin Cunningham‟s expertise on Oligocene/Miocene ichnotaxa and carbonate microfacies analysis was invaluable. Ron Reese‟s guidance and help on lithologic, geophysical, and sequence analysis was instrumental and much appreciated. A special thanks to the entire staff at the USGS Florida Water Science Center for their support and help in obtaining the material and equipment for the study. Dr. Root and Dr.

Comas were helpful in reviewing the manuscript and providing useful geophysical and hydrogeologic advice. To my family, friends, and all those who encouraged me to continue, thank you. Finally, I would like to thank my major professor Dr. Anton Oleinik for his unwavering support, guidance and patience as well his helpful expertise on sedimentology and stratigraphy; the completion of this study would not have been possible without his continued dedication.

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ABSTRACT

Author: Caroline M. Wright

Title: Sequence Stratigraphy of the Arcadia Formation, Southeast Florida: An Integrated Approach

Institution: Florida Atlantic University

Thesis Advisor: Dr. Anton Oleinik

Degree: Master of Science

Year: 2014

The Arcadia Formation is a mixed carbonate-siliciclastic rock unit that existed as a shallow carbonate ramp to platform environment during the Late Oligocene to Early

Miocene Epoch. It can be divided into two distinct, informal sections based on lithological properties: the upper Arcadia Formation and lower Arcadia Formation. The sections are part of a major, third-order sequence that can be further divided into four higher-frequency, lower magnitude sequences: ARS1, ARS2, ARS3, and ARS4. The sequence boundary separating ARS2 and ARS3 represents a drastic change in the depositional regime from a high-energy, inner ramp/platform to a lower-energy, deep outer ramp environment. ARS3 represents the period of maximum flooding and constitutes a major portion of the regressive system tract (RST) of the third order

iv depositional sequence. In certain sections, the Arcadia Formation is heavily bioturbated including ichnotaxa from the glossifungites, cruziana, and scolithos inchofacies.

Thalassinoides sp. burrows of the glossifungites ichnofacies were found to be commonly associated with firmground substrates and breaks in sedimentation. The lithofacies associations were grouped into paleodepositional environments that ranged from restricted marine to deep outer ramp with lithology ranging from grainstone to wackestone to mudstone with variable amounts of siliciclastic and phosphatic constituents. Each sequence boundary extends regionally south from Broward County to southern Miami-Dade County utilizing gamma-ray geophysical signatures unique to each sequence.

SEQUENCE STRATIGRAPHY OF THE ARCADIA FORMATION, SOUTHEAST

FLORIDA: AN INTEGRATED APPROACH

1.0 INTRODUCTION ...... 1

1.1 Objectives ...... 2

1.2 Hypothesis ...... 3

1.3 Relevance of Study ...... 3

1.4 Thesis Organization ...... 4

2.0 OVERVIEW OF THE ARCADIA FORMATION ...... 5

2.1 Geologic Setting ...... 5

2.2 Global Sea Level during the Oligocene to Miocene ...... 10

2.3 Lithology ...... 11

2.4 Age ...... 13

2.5 Stratigraphic Position of the Arcadia Formation in South Florida ...... 16

3.0 PREVIOUS SEQUENCE STRATIGRAPHIC STUDIES ...... 18

4.0 METHODS ...... 22

4.1 Review of Sequence Stratigraphic Terms ...... 25

5.0 RESULTS ...... 30

5.1 List of Lithofacies and Distribution of Ichnofossils in the Arcadia Formation

Identified by the Author ...... 30

5.1.1 Unconformity related surfaces ...... 35

5.1.2 Lithofacies 2: Glossifungites mudstone to clay ...... 36

5.1.3 Lithofacies 3: Peloidal packstone to grainstone ...... 39

5.1.4 Lithofacies 4: Peloidal, bioturbated wackestone ...... 41

5.1.5 Lithofacies 5: Sandy wackestone-packstone ...... 43

5.1.6 Lithofacies 6: Mudstone (biomicrite) to cherty claystone ...... 45

5.1.7 Lithofacies 7: Molluscan shellbed floatstone ...... 47

5.1.8 Lithofacies 8: Foraminifera-rich wackestone to packstone ...... 50

5.1.9 Lithofacies 9: Bioclastic grainstone to molluscan floatstone ...... 52

5.1.10 Lithofacies 10: Skolithos-Cruziana bioclastic-lithoclastic packstone

to grainstone ...... 55

5.1.11 Lithofacies 11: Quartz sand/silt to sandy bioclastic grainstone ...... 57

5.1.12 Lithofacies 12: Whole molluscan skeletal floatstone ...... 59

5.1.13 Lithofacies 13: Bioturbated carbonate sandstone ...... 61

5.1.14 Lithofacies 14: carbonate sandstone ...... 63

5.2 Sequence Stratigraphy ...... 66

6.0 DISCUSSION ...... 71

6.1 Paleoenvironments of Lithofacies ...... 71 vii

6.1.1 Restricted lagoon environment ...... 72

6.1.2 Open shelf lagoon ...... 73

6.1.3 Inner ramp environment ...... 78

6.1.4 Outer ramp environment ...... 79

6.2 Regional Correlation of Sequence Boundaries ...... 80

7.0 CONCLUSION ...... 83

APPENDIX ...... 87

BIBLIOGRAPHY ...... 107

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LIST OF TABLES

Table 1. Comparison of previous sequence stratigraphic interpretations for the

Arcadia Formation ...... 19

Table 2. Terminology of cycle hierarchies as they relate to base sea-level changes...... 26

Table 3. List of ichnotaxa present in the Arcadia Formation ...... 30

Table 4. List of lithofacies identified in the G-2984 Core ...... 31

Table 5. Sequences and cycles with lithofacies associations throughout the Arcadia

Formation ...... 69

Table 6. Profile across the subjacent Suwannee shallow-water carbonate ramp

displaying the dominant occurrence of grains, depositional texture, and

depositional structures across subenvironments...... 76

LIST OF FIGURES

Figure 1. Structural features affecting shallow Tertiary and Quaternary sediments

of the Florida Platform ...... 6

Figure 2. Location of principle test corehole G-2984 ...... 7

Figure 3. Cross-section of the Florida/Bahamas Platform showing distribution and

thickness of basement rocks underlying Tertiary carbonate rocks...... 8

Figure 4. Paleogeography and evolution of the Suwannee Channel on the

southeastern Coastal Plain during the Paleocene and Eocene time...... 9

Figure 5. Eustatic sea-level curve (Haq et al., 1988) during the late Oligocene to

Pleistocene ...... 11

Figure 6. Lithofacies of the Arcadia Formation identified at the southern platform

margin...... 12

Figure 7. Chronostratigraphy of the Arcadia Formation in the southern peninsula of

Florida as determined from previous studies ...... 15

Figure 8. Stratigraphic chart showing the position of the Arcadia Formation and

general lithology ...... 17

Figure 9. Location of study area, wells used, and position of cross-section line...... 23

Figure 10. Systematic hierarchical classification of sequences and sequence

boundaries ...... 28

Figure 11. Stratigraphic column showing distribution of ichnofossils in the Arcadia

Formation ...... 34

Figure 12. Lithofacies 1: Examples of discontinuity surfaces in the Arcadia

Formation ...... 36

Figure 13. Lithofacies 2: Glossifungites mudstone to claystone ...... 38

Figure 14. Lithofacies 3: Peloidal packstone to grainstone ...... 40

Figure 15. Lithofacies 4: Peloidal, bioturbated wackestone ...... 42

Figure 16. Lithofacies 5: Sandy wackestone to packstone ...... 44

Figure 17: Lithofacies 6: Carbonate mudstone (biomicrite) to cherty claystone ...... 46

Figure 18. Lithofacies 7: Molluscan shell bed floatstone ...... 48

Figure 19. Photomicrographs of microfacies present in lithofacies 7 ...... 49

Figure 20. Lithofacies 8: Foraminifera rich wackestone to packstone...... 51

Figure 21. Lithofacies 9: Bioclastic grainstone to molluscan floatstone ...... 55

Figure 22. Lithofacies 10: Skolithos-Cruziana bioclastic-lithoclastic grainstone ...... 57

Figure 23. Lithofacies 11: Quartz sand/silt to sandy bioclastic grainstone ...... 59

Figure 24. Lithofacies 12: Whole molluscan skeletal wackestone to floatstone ...... 60

Figure 25. Lithofacies 13: Bioturbated carbonate sandstone ...... 63

Figure 26. Lithofacies 14: Phycosiphon carbonate sandstone ...... 65

Figure 27. Interpreted sequence stratigraphy of the Arcadia Formation in core G-

2984 ...... 67

Figure 28. Cross section of interpreted carbonate ramp depositional environments

of the Arcadia Formation showing distribution of interpreted lithofacies ...... 72

Figure 29. Cross section of Arcadia Formation showing regional correlation of

sequences and sequence boundaries ...... 82

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CHAPTER 1

1.0 INTRODUCTION

Few studies have been done that examine the ichnofaunal assemblages within the

Arcadia Formation. Ichnofossils are traces produced by organisms on or within a substrate and include all features related to bioturbation, bioerosion, and biodeposition

(Bromley, 1990, 1996; Buatois and Mangano, 2011; Pemberton et al., 1992). Ichnofossils can be classified as either biogenic sedimentary structures (bioturbation, biostratification, and biodeposition) or as bioerosion structures (borings, scrapes, and etchings). Soft- bodied organisms are commonly the producers of trace fossils, and due to their morphology, are rarely preserved as body-fossils. Infaunal organisms that produce biogenic structures are strongly controlled by environmental factors and tend to occur preferentially in certain depositional environments, making ichnotaxa associations an excellent indicator of paleobathymetery and paleodepositional environments. Ichnotaxa associations that are characteristic of a precise set of environmental conditions are classified as ichnofacies (Seilacher, 2007).

The purpose of this research was to provide a case study of the use of ichnofossils as sequence stratigraphic surface indicators within the Arcadia Formation from continuous core data. This was done in an effort to provide further evidence of

1 marine hydrodynamic changes and shifts in sedimentary patterns during the Late

Oligocene to Early Miocene in South Florida. Because the Arcadia Formation is generally composed of fine-grained lithologies, such as clays and mudstones, it was reasonable to assume that the quality and quantity of trace fossil preservation would be sufficient to provide paleoenvironmental interpretations.

This case study demonstrates that the presence of ichnotaxa in the Arcadia

Formation can be used to define and analyze sequence stratigraphic surfaces. A systematic list of ichnotaxa was established, which were identified from continuous core of the Arcadia Formation, and constructed together with their occurrence (vertically) within the formation. Finally, a detailed lithologic description was completed that identified lithofacie occurrences along with a paleoenvironmental and sequence stratigraphic interpretation.

1.1 Objectives

The objective of this study was to create a sequence stratigraphic framework based on an integrated method that utilized lithological, ichnological, and geophysical data of the principle continuous core G-2984. The second objective to laterally delineate the interpreted sequences and their component system tracts by correlating them with previously identified sequence stratigraphic units within the Arcadia Formation.

1.2 Hypothesis

It is hypothesized that while there may be a lithological difference within the

Arcadia Formation between Broward County and the Florida Keys, the sequence of sea- level events during the Late Oligocene to Middle Miocene can be accurately correlated on a local scale using sequence boundaries and ichnofacies within the Arcadia Formation.

Using a combination of lithostratigraphic, ichnologic, and geophysical data, sequence boundaries can be identified and given an order of tectono-eustatic/eustatic cyclicity.

1.3 Relevance of Study

The Arcadia Formation, part of the Hawthorn Group, acts as the major confining unit between the Biscayne Aquifer and the Floridan Aquifer and as a result is an important hydrostratigraphic and economic unit in South Florida. Groundwater accounts for the majority of Florida‟s drinking water, supplying almost 90 percent of the state‟s demand. Two other major sources of groundwater also present include the Intermediate and Floridan Aquifer systems. The Surficial Aquifer system incorporates the Biscayne

Aquifer and has been the primary source of groundwater for South Florida (SOFIA).

However due to increased water usage and demands in southeastern Florida, the Biscayne

Aquifer is no longer sufficient (Reese, 2000). Alternative groundwater sources are currently being explored. The main prospect for a secondary groundwater source is the

Upper Floridan Aquifer. The Upper Floridan Aquifer is composed of Hawthorn Group sediments which includes the Arcadia Formation (Scott, 1988). This study will help to

3 better define sequences present in the Arcadia Formation which can be utilized to predict spatial variability in lithological and hydrogeological properties within the formation.

1.4 Thesis Organization

Following the introduction, this thesis is organized into these subsequent chapters:

Chapter 2, Overview of the Arcadia Formation, discusses the geologic setting of the study area, lithology and previous studies of the Arcadia Formation., Chapter 3, Previous

Sequence Stratigraphic Studies, discuss previous literature defining sequence stratigraphic interpretations of the Arcadia Formation., Chapter 4, , Methods, will describe the collection, handling, and storage of materials and data. It will also define the lithological, ichnological, and sequence stratigraphical techniques used. Chapter 5,

Results, will contain descriptive and graphical analysis performed by the author. Chapter

6, Discussion, provides an interpretation of the data obtained from the study and correlations with previously collected data from other literature sources, Chapter 7,

Conclusion, contains the results of the study, problems encountered with interpretations and data collection and possible ideas for future studies. Chapter 7 is followed by appendices and bibliography.

CHAPTER 2

2.0 OVERVIEW OF THE ARCADIA FORMATION

2.1 Geologic Setting

The Arcadia Formation is a subsurface geologic unit in South Florida that formed within the Okeechobee Basin (Figure 1), which was a structural feature that influenced

Tertiary sediments of the Florida Platform (Scott, 1988). The study area is located along the southeastern Atlantic coastal zone of the South Florida platform, within the Atlantic

Coastal Ridge and Okeechobee Basin physiographic provinces (Figure 2) (McKinney,

1984). The eastern edge of the Florida platform boarders the Atlantic Ocean and the western edge of the platform boarders the Gulf of Mexico. The Platform extends nearly

400 miles south of the Gulf Coastal Plain and at its widest extends approximately four hundred miles longitudinally (Scott, 1992). It has a broad, gentle sloping ramp on the west Florida Shelf that terminates at the Florida Escarpment where it plummets to nearly

3, 200 meters below sea-level into the Gulf of Mexico (Hine, 2009). Generally “South

Florida” has been designated as the part of the Platform that is to the south of Lake

Okeechobee.

Figure 1. Structural features affecting shallow Tertiary and Quaternary sediments of the Florida Platform

(modified from Scott, 1988). Boxed area indicates study area located in South Florida.

Figure 2. Location of principle test corehole G-2984, located on the Hillsboro canal in the northeast section of Broward County.

Tertiary carbonate rocks that make up the Florida Platform rest on Paleozoic to

Mesozoic age igneous and metasedimentary basement rocks (Applin and Applin, 1965;

Hine, 2009; Scott, 1992) (Figure 3). The carbonate platform that we recognize today became fully developed as a thick succession of carbonate rock complexes in the middle

Jurassic and was originally connected to the Bahamas Platform (also known as the

Florida-Bahamas-Platform) creating the largest shallow-water carbonate platform in the world (Brewster et al., 1997; Hine, 2009; Randazzo, 1997). 7

Figure 3. Cross-section of the Florida/Bahamas Platform showing distribution and thickness of basement rocks underlying Tertiary carbonate rocks (modified from Randazzo, 1997).

Sediments of the Arcadia Formation were deposited during the Oligocene to

Miocene period. During this time, vertical faulting during the Cuban Orogeny in conjunction with increased siliciclastic input from the Appalachians due to increased rates of erosion, caused the diversion of the paleo-Gulf Stream and “in filling” of the

Suwannee Channel (McKinney, 1984). The Suwannee Channel (Figure 4) was a natural, mild depression that channelized flow between southern Georgia and northern Florida and acted as a barrier and facies boundary between the clastic sediments of the

Appalachian Piedmont and the in situ carbonate sediments of the Florida Platform

(Alppin and Alppin, 1965; Chen, 1965; Hull, 1962; Paul and Popenoe, 1985; McKinney,

1984). A strong easterly flowing paleocurrent connected the Gulf of Mexico and the

Atlantic Ocean through the Suwannee Channel (also known as the Gulf Trough or

Suwannee Strait (Dail and Harries, 1892).

Figure 4. Paleogeography and evolution of the Suwannee Channel on the southeastern Coastal Plain during the Paleocene and Eocene time (from McKinney, 1984). Arrows indicate inferred direction of paleocurrents.

Infilling and closure of the Suwannee Channel introduced large quantities of siliciclastic sediment from the Appalachians to the Florida Platform through fluvial transport. By late Oligocene to Miocene time, much of the Florida Platform had become a mixed carbonate-siliciclastic environment with clastic sediments being transported as far as the southern platform margin (today Florida Keys) (Brewster-Wingard et al., 1997;

Cunningham et al., 1998; Denny et al., 1994; McKinney, 1984; Missimer, 2002; Riggs,

1979; Scott, 1988). The influx was so significant in the late Miocene that carbonate deposition ceased in all but the southern portion of the platform where the mixed carbonate-siliciclastic deposit forms the foundation for the Pleistocene to Holocene southern Florida carbonate shelf margin and discontinuous reefs (Cunningham et al.,

1998 ; McNeil et al., 2004; Warzeski et al., 1996)

2.2 Global Sea Level during the Oligocene to Miocene

From the late Oligocene to the Miocene, global sea-levels fluctuated from slightly below current sea-level to, at its highest, 100 meters above current sea-level.; due in part to increased glacial influence (Haq et al., 1988). Sea-level fluctuations partially controlled by glacio-eustasy resulted in third-order (0.5-3 my) sequence cycles. Third- order sequence cycles can be recognized on the scale of seismic data and through the identification of individual cycles of accommodation creation and destruction. The highest sea levels occurred during the early Miocene, with sea-levels reaching an excess of 100 meters above present day levels (Figure 5). During this time period, from the late

Oligocene to early Miocene, the sediments of the Arcadia Formation were deposited.

Figure 5. Eustatic sea-level curve (Haq et al., 1988) during the late Oligocene to Pleistocene (modified from Cunningham et al, 2003). Sea level curve represents a third-order sequence cycle (0.5-3 my) and shows significant eustatic sea-level rise from the late Oligocene to middle Miocene.

2.3 Lithology

The Arcadia Formation is characterized by Scott (1988) as a variably indurated limestone to dolostone with varying amounts of phosphate, clay, and quartz with a dominant carbonate sedimentary texture ranging from mudstone to grainstone (Figure 6).

Phosphorite horizons are common in the sediments of the Miocene Hawthorn Group of south Florida and are associated with nutrient-rich marine upwellings during Miocene sea-level fluctuations (Hine, 2009; Riggs, 1980; Mallinson et al., 1994). Erosion and reworking of phosphorite during marine regressions redeposited the phosphorite as phosphatic particles (sand to gravel size) over the entire carbonate platform. Condensed,

11 phosphatic crust can be used for marker horizons indicating maximum flooding surfaces

(MFS) (Follmi, 1996).

Figure 6. Lithofacies of the Arcadia Formation identified at the southern platform margin: (A)

Arcadia/Suwannee sequence boundary, (B) skeletal wackestone, packstone, well-washed packstone, grainstone, (C) molluscan floatstone and rudstone, (D) benthic foraminifer grainstone, (E) red algal rudstone, grainstone, packstone, and wackestone, and (F) euhedral dolomite.(from Cunningham et al.,1998).

Induration varies throughout the formation as recrystallization and/or dolomitization varies (Brewster-Wingard et al., 1997). The limestone ranges in color from white to yellowish gray and are low to highly recrystallized with a general mineralogy of low magnesium calcite with minor amounts of dolomite and aragonite,

12 variably porous, and a sedimentary texture of mudstone to grainstone with skeletal fragments, mollusks, benthic foraminifers, red algae, and echinoids constituting the principle grains (Cunningham et al., 1998; Scott, 1988). The dolostone ranges in color from yellowish gray to light olive gray, are micro- to finely crystalline, and are slightly porous to very porous with moldic porosity (Scott. 1988). The clays generally consist of a mineral suite of smectite, illite, palygorskite, and sepiolite (Reynolds, 1962). Chert is also common, with the chert appearing to be formed from silicified clays and dolosilts (Scott,

1988). The clay and fine-grained mudstone components of the Arcadia Formation decrease towards the southern edge of the Florida Platform.

The strata of the Arcadia Formation have a low angle dip trending to the south and southeast direction generally thickening towards the Okeechobee Basin (Scott, 1988), cropping out in the northwest around the Ocala High (Missimer, 2002). The top of the formation ranges from 30 meters (100 feet) above mean seal level (MSL) in north central

Florida to greater than 229 meters (750 feet) below MSL in south eastern Florida (Scott,

1988). Thickness ranges from 0 meters North of Palm Beach County to 200 meters South of Palm Beach County (Lynn et al., 1996).

2.4 Age

The Arcadia Formation was originally dated as early Miocene to no older than late early Miocene by Scott (1988) based on mollusks and trace fossil assemblages.

Brewster-Wingard et al. (1997) found that the Arcadia Formation was middle early

Oligocene to at least early Miocene in age using biostratigraphic, lithostratigraphic, and chronostratigraphic techniques. Missimer (2002) used strontium isotope dating and identified the age to be between 26.6 to 12.4 million years old (Ma) (Chattian-

Serravalian). Cunningham et al (2003) found the age of the Arcadia Formation to be between 24.1 to 19.39 Ma (Chattian-Burdigalian) using strontium-isotope and chemostratgigraphy. Guertin et al (2000) determine the age to be Late Oligocene to

Middle Miocene (Figure 7).

Figure 7. Chronostratigraphy of the Arcadia Formation in the southern peninsula of Florida as determined from previous studies. Ages are according to the time scale of the International Commission on

Stratigraphy (2013). Formation boundary ages were determined by the respective authors.

2.5 Stratigraphic Position of the Arcadia Formation in South Florida

The Arcadia Formation in the study area is a unit within the Hawthorn Group, which consists of the Arcadia and Peace River Formations (Figure 8). The Arcadia

Formation is subdivided into two members, the Tampa Member and the Nocatee

Member. Both the Tampa and Nocatee Members are not recognized throughout the entire section (Scott, 1988). The Arcadia Formation is overlain by the Peace River Formation and in some southern sections of the study area the formation is overlain by the newly proposed Stock Island and Long Key Formations (Cunningham et al., 1998; Guertin et al., 2000). Subjacent to the Arcadia Formation is generally the Suwannee Formation; however, in some sections the Suwannee Formation is absent resulting in the Arcadia

Formation directly overlaying the Avon Park and Ocala Formations (Cunningham et al.,

2003; Missimer, 2002; Scott, 1988; COSUNA, 1988; Hammes, 1992). The overlying

Peace River Formation is dominantly siliciclastic, composed of clay-rich sandstone and diatomaceous mudstone (Cunningham et al, 1998).

Figure 8. Stratigraphic chart showing the position of the Arcadia Formation and general lithology (modified from Reese, 2000)

CHAPTER 3

3.0 PREVIOUS SEQUENCE STRATIGRAPHIC STUDIES

Previous stratigraphic frameworks for the Arcadia Formation were completed for the interior southwestern platform by Missimer (2002) and for the southernmost edge of the platform by Cunningham (1998) and Guertin (2000). A comparison of these sequences and their descriptive attributes are given in Table 1. The Arcadia Formation was found to contain a composite sequence and multiple (super) sequences. The composite sequence was found to contain four higher order (lower magnitude) sequences that contain multiple higher-order cycles. These were delineated by Cunningham et al

(1998) and Guertin (2000) as high-frequency sequence 1 (HFS1), high-frequency sequence 2 (HFS2), high-frequency sequence 3 (HFS3), and high-frequency sequence 4

(HFS4). A high-frequency sequence is a fourth-order sequence that makes up a composite or depositional sequence (Kerans and Tinker, 1997). Supersequence A,

Supersequence B, sequence C, and sequence D were identified by Missimer (2000) in the

Arcadia Formation from samples located on the west, central South Florida platform edge. Supersequence A and B are lower order (higher magnitude) sequences than sequences C and D.

Table 1. Comparison of previous sequence stratigraphic interpretations for the Arcadia Formation

The top of the Arcadia Formation is characterized by a hiatal disconformity that is considered a major sequence boundary. The unconformity is characterized by black phosphorite clasts which mark the boundary between the shallow, inner ramp facies of the upper section of the Arcadia Formation and the overlying dominantly siliciclastic facies of the Peace River/ Long Key Formation (Cunningham et al., 1998).

The base of the Arcadia Formation is a major sequence boundary that is characterized by a disconformity where the lower Oligocene Suwannee Limestone is disconformably overlain by the upper-lower Oligocene Arcadia Formation (Brewster-

Wingard et al., 1997; Missimer, 2002, Cunningham et al, 1998). Cunningham et al

(1998) and Guertin et al (2000) identified this contact as a major sequence boundary based on the identification of an 8.1 m.y. hiatus between the Suwannee Formation and

Arcadia Formation (Guertin et al, 2000)

The boundary separating the base of the Arcadia Formation and the subjacent

Suwannee Limestone shows evidence of surface to near-surface exposure to meteoric water; however, no evidence of extensive chemical weathering has been identified

(Brewster-Wingard et al., 1997). A hiatus is present between the Oligocene sediments of the Suwannee Formation and the lower Miocene sediments of the Arcadia Formation.

Brewster-Wingard et al (1997) termed this hiatal unconformity the east coast unconformity. The unconformity was most likely the result of migration of the paleo-

Gulf Stream across the Florida Platform in response to sea-level fluctuations (Riggs,

1984; Brewster-Wingard et al., 1997). The upper section of the Arcadia Formation (lower

Oligocene) is overlain by lower Miocene to lower Pliocene Peace River Formation sediments and contains a major unconformity (Brewster-Wingard et al., 1997,

Cunningham et al, 1998; Scott, 1988). The unconformity is marked by the presence of a regionally extensive phosphatic gravel layer which is regionally extensive, being present at the southern edge of the Florida Platform (Florida Keys) and in the north central region

(Cunningham et al., 1998; Brewster-Wingard et al, 1996; Guertin et al., 2000; McNeil et al., 2004; Missimer, 2002; Warzeski et al., 1996).

CHAPTER 4

4.0 METHODS

One thousand and three hundred feet of two inch diameter continuous rock core samples were collected from the G-2984 borehole for this study. A Schramm T450MIIA mobile drill rig with a wireline hoist for continuous coring was used to drill and collect the core samples. The G-2984 core is archived at the United Stated Geological Survey

(USGS) Florida Water Science Center (WFSC), Davie, Florida. Previous core descriptions and supplemental geophysical well logs from five additional wells were used to correlate sequences identified in the G-2984.the and include, from south to north: W -

17086, W- 17156, MO-130, DF-1, and Sun-BTW (Figure 9).

The rock sample collected from the test core G-2984 are predominantly mudstone and hard, indurated limestone or less commonly soft, friable limestone. Twenty-five thin sections were made from epoxy impregnated chips, which was provided by the U.S.

Geological Survey, from discrete core depths and were analyzed for benthic and planktonic foraminifera as well as diagenetic alterations. In indurated samples, the core was slabbed at the USGS FWSC to reveal the internal structure of the rock samples and any traces of ichnofossils, if present. Subsequent analysis was performed in the USGS

FWSC Carbonate Aquifer Characterization Laboratory. The G-2984 continuous core was collected at 10 foot intervals and subsequently segmented into 2 foot intervals for storage and analysis. 22

Acquisition of lithologic and geophysical data for a number of wells included publically released data from the USGS Nation Water Information Systems (NWIS) and the South

Florida Water Management District (SFWMD) DBHYDRO Environmental Database.

Data obtained included lithologic descriptions, hydrostratigraphy, geophysical logs, and construction data.

Figure 9. Location of study area, wells used, and position of cross-section line. Continuous core is located in Broward County. Principle well indicates that well was studied by author extensively. All other wells identified are supplementary wells.

Recognition of sedimentary facies was based on (1) lithology and lithological breaks including grain size, grains (quartz, clay, phosphorite, micrite, and allochems

(macro- and microfossils), (2) sedimentary structures including bedding types (cross-, wavy-, planar-, and massive-bedded), (3) biogenic structures, (4) and diagenetic structures/textures (chert nodules). Color descriptions were made according to the geological Rock Color Chart based on the Munsell color system (Rock-Color Chart

Committee, 2009). Depositional textures are according to Embry and Klovan (1971) after

Dunham‟s (1962) classification of limestone according to depositional texture. For the purposes of this research and following Dunham‟s classification, the term mudstone refers to a rock that is primarily composed of lime mud. Micrite would be an equivalent term according to Folk‟s (1962) classification.

The method for trace fossil identification was based on their basic morphological characteristics including configuration (burrow structure and material), orientation, fill, wall lining, and position with respect to stratification (Pickerill, 1994). Five archetypal marine ichnofacies are identified, two with hard- to firmground substrates (Trypanites and Glossifungities) and three with softground substrates (Skolithos, Cruziana,

Zoophycos, and Nereites). Ichnofossils were identified with the aid of literature of ichnofossils in carbonate and clastics environemnts (Gerald. and Bromley, 2008; Buatois, and Mangano, 2007).

Geophysical wireline borehole data such as natural gamma ray, spontaneous potential, and caliper logs were used to help determine presence of phosphorite and changes in grain size. Natural gamma ray logs were used to measure the natural 24 radioactivity of the formation and were a useful tool to give an estimate of the grain size, mineral content, and porosity. Borehole geophysical logs were acquired from NWIS,

DBHYDRO, and USGS FWSC. The standard output format for borehole logs is Log

ASCII (LAS) file format which can be opened on Earthfx Viewlog software. This software was available for use at the USGS FWSC in Davie, Florida

Optical borehole images (OBI) and acoustic borehole images (ABI) were viewed when the data were available for wells within in the study area. These logs provided down-hole imaging of the borehole to help identify dissolution features, and areas of bioturbation, and provide a better resolution on internal structure.

4.1 Review of Sequence Stratigraphic Terms

In this study, a sequence boundary is considered to be a distinct stratigraphic surface that represents a change in depositional trends. Orders of cyclicity are determined based on empirical evidence observed at key stratigraphic surfaces with the consideration of the time parameters previously determined for the Arcadia Formation. These surfaces have characteristic properties that allow for their recognition and interpretation and include a subareial unconformity (SU), a shoreline ravinement (SR), a maximum flooding surface (MFS) and a maximum regressive surface (MRS) (Embry et al., 2007).

A hierarchy of sequence boundaries was established that define six orders of sequences and sequence boundaries, each order correlating with cycle duration and base sea-level change: 1st order, 2nd order, 3rd order, 4th order, 5th order, and 6th order (Vail et al., 1977;

Embry, 1993, 1995; Goldhammer, 1991). The sequence stratigraphic unit and its associated cycle order and duration are given in Table 2.

Table 2. Terminology of cycle hierarchies as they relate to base sea-level changes. Modified from Goldhammer et al (1991). Tectono- Eustatic/ Eustatic Cycle Relative Sea Level Order Sequence Stratigraphic unit Duration (my) Amplitude (m)

First >100

Second Supersequence 10-100 50-100

Depositional Sequence Third Composite Sequence 1.0-10 50-100

High Frequency Sequence (HFS) Parasequence and Fourth Cycle Set .01-1.0 1-150

High Frequency Cycle Fifth and Parasequence .01-0.1 1-150

Within a basin, the sequence boundaries generated by the largest magnitude (>

100-200m) base level change are categorized as 1st order sequence boundaries (SBs). 1st

26 order SBs are generally the result of significant changes in tectonic and sedimentary regime and are associated with large amounts of erosion and significant deepening

(Embry et al, 2007; Kerans and Tinkers, 1997). Lower magnitude (higher order) sequence boundaries (4th, 5th, and 6th) are characterized with little erosion and deepening, and are associated with climatic driven eustatic base level changes.

Multiple criteria were used to identify sequence boundaries and include: 1) a significant change in lithology and flora and fauna assemblages, 2) presence of an exposure horizon, such as calcrete, thin clay, or development of the Glossifungites ichnofacies, 3) presence of an exposure horizon, such as quartz and phosphate gravel or karstification, resulting in a significant change in the natural gamma ray signature interpreted from geophysical well logs, 4) facies dislocation (shallow facies rocks lie unconformably on deeper facies rocks) or a turnaround from progradational to retogradation cycles, 5) a significant change in grain-size, 6) a change in the degree of cementation and/or mineralization of iron oxides and calcium phosphates, and 7) a change in the degree of lithification (Pemberton et al., 2000; Emery and Myers, 1996;

Miall, 2010; Cunningham et at., 1998; Kerans and Tinker, 1997; Missimer, 2002; Guertin et al., 2000). The general rule when assigning a hierarchical classification to sequences states that “a sequence cannot contain within it a sequence boundary that has an equal or greater magnitude (equal or lower order) than that of its lowest magnitude (higher order) boundary” (Embry et al., 2007) (Figure 10).

Figure 10. Systematic hierarchical classification of sequences and sequence boundaries (from Embry et al.,

2007).

In carbonate settings, periods of non-deposition or erosional exhumation with associated submarine compaction or cementation create firmgrounds or hardgrounds

(Droser et al., 2002; Pemberton et al., 2000). In core samples, Ekdale et al (1984) found that depositional breaks associated with firmgrounds or hardgrounds have specific ichnofacies associated with them such as the Glossifungites (firmground) and Trypanites

(hardground) ichnofacies. Substrate controlled ichnofacies such as the Glossifungites and

Trypanites ichnofacies are common on transgressive or ravinement surfaces (surface of non-deposition and/or erosion) (Gerald and Bromley, 2008). Given that substrate-

28 controlled ichnofacies are commonly associated with omission surfaces, they can be regarded as being equivalent to discontinuities in the stratigraphic record (Pemberton et al., 2000).

CHAPTER 5

5.0 RESULTS

5.1 List of Lithofacies and Distribution of Ichnofossils in the Arcadia Formation

Identified by the Author

A list of identified ichnofossils present (Table 3) in the Arcadia Formation of the

G-2984 core as well as their stratigraphic ranges (Figure 11) within the formation are described below. Additionally, in order to compile an accurate sequence stratigraphic interpretation, similar lithologies were grouped into lithofacies (Table 4). Lithofacies with similar depositional environments were grouped into lithofacies associations. A detailed description of each lithofacies is provided below. A detailed lithologic description for the G-2984 core is provided in the Appendix.

Table 3. List of Ichnotaxa Present in the Arcadia Formation

Chondrites Ophiomorpha nodosa Palaeophycus Phycosiphon Planolites Rhizocorallium Scolicia Skolithos Taenidium Terebellina Thalassinoides Zoophycos

Table 4. List of Lithofacies Identified in the G-2984 Core

Sedimentary Disconformity surface Lithofacies 2 Lithofacies 3 Lithofacies 4 Lithofacies 5 Facies Bioturbated mudstone Peloidal-intraclasts- Peloidal, bioturbated Sandy bioturbated skeletal rudstone packstone mudstone/wackestone Depositional Period of erosional or Restricted platform/ deep Open platform/inner Restricted Intertidal (peritidal) Environment nondeposition lagoon ramp platform/intertidal

Color Black to white Yellowish gray to light White White to yellowish gray olive gray Grain Types Micrite, clay, quartz sand Peloids, foraminifera, Peloids, micrite (matrix), Micrite, granule-sized (in order of (silt to very fine) and, microscopic mollusks microscopic skeletal intraclasts, granule abundance) phosphatic sand (silt to (gastropods), intraclasts, fragments, quartz sand phosphorite (10%)fine very fine) phosphatic sand (fine to (silt to very fine), and skeletal fragments with medium), and micrite phosphatic sand (silt to abundant amounts of quartz (matrix) very fine) sand (very fine) and variable phosphatic sand (fine to medium)

Grain Size Clay to silt Medium to coarse Silt to very fine Clay to medium sand Sedimentary Massive to bioturbated Large (>2mm) skeletal Massive to completely Soft sediment Structures with hardgrounds that components in a grain bioturbated resulting in deformation/slumps have been extensively supported matrix of mottled fabric possibly from bioturbation, bioturbated peloids and skeletal brecciation cracks, and grains with minor fenestral porosity amounts of micrite Biota Benthic forams Microscopic gastropods Microscopic mollusks, and foraminifera rare large (>2in) bivalves, and foraminifera Biogenic Chondrites, Taenidium, Skolithos, Palaeophycus, Indistinct burrows Structures Palaeophycus, Planolites, Thalassinoides, and Thalassinoides Planolites background overprint

Sedimentary Lithofacies 6 Lithofacies 7 Lithofacies 8 Lithofacies 9 Lithofacies 10 Facies Cherty carbonate Hyotissa packstone / Moldic, sandy Bioclastic floatstone to Cruziana-Skolithos mudstone to claystone wackestone wackestone/packstone rudstone grainstone Depositional Deep shelf Shallow outer ramp Restricted lagoon Inner to outer ramp Intertidal to subtidal Environment (transgressive/ by pass surface) Color Yellowish gray to pale Light gray to white greenish yellow Grain Types Carbonate mud, variable Micrite (matrix) Quartz sand (fine to Carbonate mud (matrix), Quartz sand (very fine to (in order of amounts of clay, and Hyotissa medium), clay/carbonate molluscan skeletal medium 40%), phosphatic abundance) minor phosphorite (silt to Quartz sand (medium to mud, mollusks (lagoonal fragments, micritized sand (fine to medium; 1- very fine) very fine) species: oysters and grains, peloids, and 2%), micrite (matrix), Phosphorite sand (sand gastropods) phosphatic intraclasts skeletal shell fragments, to gravel) sand (fine to medium), disk shaped foraminifera Mollusks skeletal oysters (in growth fragments position), intraclasts, and mollusk skeletal

fragments 32

Grain Size Clay Clay to cobble (>30cm) Clay to medium Clay to pebble Very fine silt to medium

Bedding and Planar, mm scale Large dissolution cavities Massive, complete Well indurated with Massive bedding, sedimentary laminations, laminar dark from bioturbated with possible hardgrounds, abundant homogenized from complete structures chert accumulations, and karst solution diagenesis brecciation cracks or root molds and micrite casts, bioturbation rare local coarse slump Localized phosphatic molds (?). Moldic to moldic, interparticle and breccia interbedded crusts vuggy porosity and intraparticle porosity, and possibly fracture localized porosity. Interbedded phosphatization/ coarse terrigenous dolomitization material Biota Mollusks (bivalves, gastropods), and pelecypods Biogenic Silicified burrows at Boring (Entobia) Burrows (bivalves?) Molds and casts of Ophiomorpha, Structures hardgrounds backfilled with coarse, mollusks and coral Rhizocorallium, Planolites, sandy/phosphatic polyps and borings into Scolicia, Thalassinoides sediment skeletal grains Palaeophycus

Sedimentary Lithofacies 11 Lithofacies 12 Lithofacies 13 Lithofacies 14 Facies Muddy quartz sand/silt Whole mollusk floatstone Rhizocorallium mollusk Phycosiphon carbonate fragment sandstone sandstone Depositional Moderate energy beach/ Open lagoon to outer Shallow inner Deep inner ramp Environment offshore sand bar ramp ramp/shoreface (foreslope) Color Light gray White to light gray Light olive gray to Light gray yellow gray to dark yellow Grain Types Quartz grains and Whole mollusk shells in Quartz grains (50%), Quartz grains (30%) (in order of phosphatic sand (10%, micrite matrix angular to subrounded Carbonate mud (matrix) abundance) localized up to 30%), and skeletal material, Angular to subrounded minor carbonate mud. phosphatic sand (fine to skeletal fragments medium (3-5 localized up Phosphatic sand (silt to to 20%), minor carbonate v.f. sand mud, dark organics Angular intraclasts

Grain Size Fine to medium Mud to pebble Fine to medium Silt to medium sand

Bedding and Loose, unconsolidated Well indurated to poorly Massive bedding with sedimentary sand indurated with massive moderate bioturbation structures bedding that has been with interbedded lenses heavily burrowed of shell debris (mottled fabric)

Biota Gastropods (Turritela, Mollusks (bivalves and Cyprea), bivalves, and oysters) echinoids

Biogenic Ophiomorpha Phycosiphon Structures Rhizocorallium Terebellina Planolites

Figure 11. Stratigraphic column showing distribution of ichnofossils in the Arcadia Formation. 34

5.1.1 Unconformity related surfaces

A number of surfaces separate different lithofacies and mark transitional periods between depositional environments. Unconformity related surfaces occur immediately below and above major unconformities that separate different sedimentary facies, representing a distinct shift in sedimentological and hydraulic regime within the environment. These can include, (1) condensed, phosphatic gravel, (2) firmground/hardground substrates with glossifungites ichnofacies, (3) weathered

(karstification), scoured surfaces, and (4) diagenetic fabrics such as phosphatic cement, sparry calcite cement, and dolotimization.

In sections of the core that contain phosphatic gravel as shown in Figure 12 (A), it is interpreted that these formed as a result winnowing of fine-grained sediment, causing the phosphate to accumulate as pebble lag, or a transgressive palimpsest deposit, above the exposure surface. Baturin (1971) suggests that authigenic phosphate is concentrated into phosphate-rich deposits as a result of sea-level dynamics. This mechanism is adopted here to explain the occurrences of large nodular and lithified deposits of phosphate present in the sediments of the Arcadia Formation. In some areas of the core where the glossifungites ichnofacies was identified, the surface is associated with submarine

(shallow water) hardgrounds and periods of nondeposition during marine regressions.

Surfaces that have undergone karstification indicate low sea-levels and subareial exposure to meteoric waters. Scoured surfaces can result from submarine erosion and winnowing of sediment during the initial trangressive phase and indicate possible ravinement surfaces in the core.

Figure 12. Lithofacies 1: Examples of discontinuity surfaces in the Arcadia Formation. Figure shows multiple occurrences of discontinuity surfaces within the Arcadia Formation of G-2984 including: A) (core interval 592.25-592.8 ft.) shows thick phosphatic erosional lag deposit bounding the top of the Arcadia

Formation as a major unconformity, B) (core interval 605.25-605.5 ft.) shows a scoured, possibly ravinement surface with boring and burrows backfilled with coarse, phosphatic sediment, C) (core interval

623.25-623.65 ft.) shows Glossifungites burrows backfilled with coarse, phosphatic sediment suggesting a ravinement surface, D) (core interval 938.4-938.6 ft.) showing phosphatic, laminated calcrete bounding the top of a depositional sequence, and E) (core interval 1033-1034) showing karstified surface. Scale in centimeters.

5.1.2 Lithofacies 2: Glossifungites mudstone to clay

Lithofacies 2 (Figure 13) consists of a planar laminated to mottled, pale olive micritic mudstone-wackestone that has been partially homogenized from intense 36

bioturbation. Granular to coarse sand-sized phosphate clasts (1-2%) have been randomly distributed throughout the sediment from bioturbation. Some faint, but rare, wavy to planar laminae can be distinguished. The lithofacies is interrupted by several hard- to firmground surfaces represented by sharply defined burrows that are slightly deformed from compaction. Deformed burrows have been backfilled with overlying sediment and uncompacted burrows that have been backfilled with coarse sand-sized sediment.

Hardground substrates contain borings and/or diagenetic alteration such as sparry calcite cement. Burrows from bioturbation typically exhibit cross-cutting relationships. The lithofacies has a set of fining upwards grain-size trends where multiple events of fining- upwards cycles occur and are often interrupted by firm- or hardground substrate. Grain size generally grades from pebble (wackestones) to clay (mudstone). Wackestone is generally composed of coarse sand-sized phosphate and peloids supported by a micrite matrix. Ichnofauna include: Thalassinoides, Ophiomorpha (abundant), possible

Taenidium, Planolites, and Chondrites.

Figure 13. Lithofacies 2: Glossifungites mudstone to claystone. Figure shows example of common ichnological occurrences in lithofacies 2 including: A) (core interval 650.6-6501 ft.) showing

Thalassinoides (Th) burrows, B) (core interval 616.6-617 ft.) showing Chondrites (Ch) and Palaeophycus

(Pa) burrows. C) (Core interval 625.8-625.9 ft.) showing Ophiomorpha nodosa (Op) burrows, and D) (core interval 643.8-644 ft.) showing possible Taenidium (Ta) with a straight to sinus, meniscate backfill burrow structure. Scale in centimeters.

5.1.3 Lithofacies 3: Peloidal packstone to grainstone

Sedimentary facies 3 (Figure 14) is a peloidal packstone to grainstone with common micrite intraclasts. Color ranges from white (N9) to yellowish grey (5Y 7/2).

Bioclasts include peloids, granule to sand-sized coral fragments, and an assemblage of skeletal fragments and foraminifera tests. Allochems include carbonate rock intraclasts and accessory minerals include granule-sized phosphate and quartz grains (3-7%).

Lithofacies gradationally fines upwards from a grainstone to a packstone. Biogenic structures are present in the packstone however they are absent in the grainstone.

Packstone matrix is micrite with variable amounts of fine sand-sized quartz and phosphate. Grainstone has moldic to vuggy porosity. The lithofacies is also poorly indurated (friable). There are common gastropod fragments near the top of the facies and benthic disk-shaped forams throughout the facies.

Figure 14. Lithofacies 3: Peloidal packstone to grainstone. Figure shows loosely indurated grainstone (A) and packstone (B) of lithofacies 3 composed of dominantly peloids and carbonate mud. Scale in centimeters.

5.1.4 Lithofacies 4: Peloidal, bioturbated wackestone

The lithofacies contains well cemented bioclasts (1-10%), peloids (1-15%), minor quartz and phosphate, and few intraclasts (1-5%). Bioclasts are sand-sized skeletal fragments and rare, whole (greater than 2 inches in diameter) bivalve (clam) shells. The grains range in size from silt to coarse sand. The fabric is supported by micrite to wackestone matrix and shows a bioturbated fabric (mottling) with some micritization of grains (Figure 15). Facies is colonized by ichnotaxa of the Skolithos ichnofacies including Skolithos and Thalassinoides. Most burrow structures have been over printed by Thalassinoides.

Figure 15. Lithofacies 4: Peloidal, bioturbated wackestone. Figure shows high degree of bioturbation within the facies: A) (core interval 761.8-762 ft.) showing thick walled Palaeophycus (P) and vertical to

Skolithos (Sk) burrows. B) displays OBI (left) and ABI (right) images for the same interval showing moderate degree of cementation (yellow area represents higher acoustic amplitude that indicates areas of harder, more competent rock.

5.1.5 Lithofacies 5: Sandy wackestone-packstone

Lithofacies 5 (Figure 16) is a wackestone to packstone with color ranging from pale greenish yellow (10Y 8/2) to yellowish grey (5Y 5/2). Micrite is the principle constituent with accessory grains of phosphorite (5-10%) that are fine to coarse sand- sized and very fine quartz grains (5-10%) Sedimentary fabric has been destroyed due to intense bioturbation resulting in mottled fabric. Hardgrounds represented by laminated calcrete are common throughout the lithofacies along with localized areas of phosphatic cement that has replaced the micrite matrix. The facies contributes only about 2-3% of the total thickness of the formation and is only seen as a transitional lithofacies.

Figure 16. Lithofacies 5: Sandy wackestone to packstone. Figure shows (left) mottled appearance due to complete bioturbation and high percentage of quartz and phosphorite sand. The right image shows a section that has undergone differential phosphogenesis resulting in a dark blue to black staining. Scale in centimeters.

5.1.6 Lithofacies 6: Mudstone (biomicrite) to cherty claystone

The rock units that belong to lithofacies 6 generally have a light greenish grey

(5GY 8/1) to medium grey (N5), massive to laminated carbonate mudstone (biomicrite) to cherty claystone (Figure 17). Primary constituent is siliciclastic clays with variable amounts of carbonate mud and allochems. Claystone is composed of a mixture of clays including palygorskite, illite, and smectite. Opalized sections of the claystone are common. Mudstone is rich in foraminifers including uniserial and biserial small benthic foraminfers and planktonic foraminiferis, commonly globigerinids. Additional allochems include echinoderm debris and small gastropods. Matrix of the mudstone is composed of detrital, angular quartz grains, micrite, phosphate, chert, and clay. Grain size ranges from clay to mud. Accessory minerals include very fine to silt size phosphorite grains (<1%) and nodular to lenticular chert accumulations. Chert is commonly found as nodules replacing earlier lithologies or filling small cavities. Convoluted laminae around chert nodules is common suggesting early chert nodule formed prior to sediment compaction before the sediment was sufficiently buried to be compacted by overburden. Baltuck

(1985) identified black to grey chert in fine-grained limestone in the Mariana Basin where „chertification fronts‟ are the result of heterogeneous rock properties inhibiting transport of silica due to accumulations of less soluble material. Multiple „chertification fronts‟ and locally silicified hardgrounds, indicated by colonization of shallow tier burrows (Palaeoophycus) preserved through differential cementation, are common.

Bioturbation is evident by localized area of dark differential silicification highlighting porosity and permeability contrasts between burrow fill. An isolated large burrow filled

with coarse, phosphatic sand, possibly filled from a storm deposit, occurs in the middle of the lithofacies.

Figure 17: Lithofacies 6: Carbonate mudstone (biomicrite) to cherty claystone. Figure shows example of facies 6: (A) (core interval 813.1-813.3 ft.) showing common fine, mm, brown laminations, (B) (core interval 907-907.3 ft.) showing „chertification front‟ with preserved burrows of Palaeophycus,(Pa), and ,

(D) (core interval 861.95-862.2 ft.) showing common larger (>2in long) lenticular chert nodules. (C) OBI

(left) and ABI (right) images showing planar, continuous to semi-continuous, fine scale, mm laminations seen in the core). Scale in centimeters. Photomicrograph (E) shows a mixture of clays and lenses opalized 46

claystone and (F) shows cherty mudstone rich in benthic foraminifera (uniserial and biserial), and echinoderms. Along with benthic forams, planktonic foraminifera include globigerinds. Blue color is from staining from epoxy highlighting poorly indurated nature of the substrate. Photomicrographs taken at core depth 923.95 ft. in PPL at 2.5X magnification (E) and core depth 903 ft. in PPL at 5X magnification (F) .

Scale in centimeters.

5.1.7 Lithofacies 7: Molluscan shellbed floatstone

Depositional texture is a molluscan floatstone with a wackestone matrix. The most prominent feature is large, thick shelled mollusks that have been bored by encrusting sponges (Figure 18). Missimer (2002) identified the mollusk as the genus Hyotissa in a similar lithofacies in the Arcadia Formation on the Gulf coast of Florida (Collier and Lee counties). Hyotissa are large, oyster like mollusks that typically colonize shallow water hardgrounds. Grain components are whole fossil bivalves with a sandy, dolomitic skeletal wackestone to packstone matrix. The planktonic foraminifera globigerinids along with benthic foraminifera milliods and echinoderm debris are common near the top of the facies (Figure 19). An interval of bioturbated dolosilt separates two molluscan rudstone/floatstone deposits. Burrows are of the ichnotaxa Thalassinoides. Some burrows have been backfilled with coarse, phosphatic sediment from the above molluscan rudstone deposit. Grains include skeletal fragments and mollusks. Mollusks shells commonly have borings (1-2 mm) by an encrusting marine sponge Entobia (Farinati and

Zavala, 2002; Lopes, 2011). Color ranges from white (N9) to pale yellow brown (10YR

6/2). Grains range from mud to large pebble size. Accessory minerals include coarse to pebble size phosphorite and secondary phosphate cement within matrix. Large open 47

cavities indicative of karstification are abundant. Some vugs occur within in the matrix, however they are not interconnected. The top of the facies is capped by an unconformity evident by phosphatic cement, dissolution features, and diagenetic dolotimization.

Figure 18. Lithofacies 7: Molluscan shell bed floatstone. Core photographs show (A) (core interval 925.8-

926.2 ft.) large, thick shelled marine oysters (pectinids, possibly Hyotissa) with boring (arrows) from

Entobia sp. encrusting sponge., (B) (core interval 926.2-926.4 ft.) and (C) (core interval 933.3-933.5 ft.) show vertical to semi-vertical orientation of oyster shells in a wackestone matrix. Scale in centimeters.

Figure 19. Photomicrographs of microfacies present in lithofacies 7 that show: (A) rhombic, polycrystalline aggregates of dolomite floating in a micrite matrix with molluscan skeletal fragment bioclasts and (B) close up view of well-formed dolomite rhombohedrals and a longitudinal cut through a bivalve shell showing shell punctate. (C) Shows diagenetic phosphatic cement (Ph) between dolomite crystals along with dolotimization of small benthic foraminifers. Dolotimization has resulted in increased porosity. Sequence boundary (D) that shows intensive phosphitization below boundary (bottom left) along with benthic miliolids (M) foraminifer, planktonic globigerinds (Gb) foraminifers, and echinoderms. Photomicrographs taken at core depth 936 ft. in PPL at 1.25 X (A) and 5 X (B) magnifications, 926.45 ft. at 10X in PPL (C), and at 924.75 ft. in PPL at 5X magnification.

5.1.8 Lithofacies 8: Foraminifera-rich wackestone to packstone

Depositional texture of lithofacies 8 is a well cemented, bioclastic to lithoclastic packstone to wackestone (Figure 20). Approximately half of the bioclastic grains have been dissolved resulting in moldic and intraparticle porosity. Dominant bioclasts and lithoclasts include planktonic foraminifera (globigerinids), skeletal fragments (fine sand to small pebble size), peloids, gastropods, mollusks and micrite intraclasts. Some grains have undergone partial to complete micritization. Color ranges from yellowish grey (5Y

8/1) to light grey (N7). Sedimentary structures include wavy to convolute bedding, possibly the result of soft-sediment deformation or burrowing. Facies contains large cavities that have been backfilled with coarse bioclastic, phosphatic sand. Accessory grains include quartz (25-30%) and phosphorite (3-5% average but 20% localized).

Figure 20. Lithofacies 8: Foraminifera rich wackestone to packstone. Core photographs show molds of bivalves and partial to complete shell bioclasts (A), deformed mold of a gastropod and molluscan shell

fragments (B) and a large diameter burrow (C). (D) OBI (left) and ABI (right) show disturbed sediment fabric from intense bioturbation creating areas of lower competency evident by large, low-amplitude darker areas in the ABI. Photomicrograph (E) shows packstone rich in Globigerina sp. (Gb) with an abundant amount of angular to subangular quartz grains surrounded by dark micrite matrix. Photomicrograph was taken at core depth 948.06 ft. in PPL at 2.5X magnification. Scale in centimeters.

5.1.9 Lithofacies 9: Bioclastic grainstone to molluscan floatstone

Depositional texture is a coated, worn bioclastic packstone to floatstone.

Lithofacies is composed dominantly of peloids and molluscan skeletal fragments in a dense micrite matrix with percent micrite increasing upsection (Figure 21). Other allochems include micrite intraclasts, peloids and carbonate mud as matrix. Peloids are irregular in size and texture and appear to be the result of micritized bioclasts. Quartz is a minor constituent contributing to less than 5% of the facies composition and when present is angular to subangular. Grades into a floatstone towards the top of the facies that is supported in a well cemented micrite and sparry calcite cement with common granule-size carbonate intraclasts.

Rare hardground alteration usually at the top of the facies that is associated with lag deposits. Color ranges from light gray (N7) to white (N9). Fauna is dominantly mollusks gastropods, bivalves, and large pelecypods that have been micritized towards the top of the facies. Some shells have been dissolved and partially filled with carbonate mud and partially replaced with finely crystalline to granular sparry calcite cement.

Porosity is almost completely intraparticle or moldic porosity that is poorly to moderately

connected. Small (< 1 cm in diameter) borings are present on some shells and believed to be a result Entobia sp., an encrusting sponge. Foraminifera present are of the families

Elphidiidae, Miliolidae, and Rotaliida. On a typical carbonate platform, Elphidiidae and

Miliolidae are common in the restricted interior. In recent carbonate embayment sediments, Ammonia sp. of the Family Rotaliidae are brackish water fauna common in the restricted interior of the platform (Lidz and Rose, 1989).

Figure 21. Lithofacies 9: Bioclastic grainstone to molluscan floatstone. Core photographs (A) show in the left (core interval 1009.1-1009.6 ft.) peloidal packstone to grainstone with casts of small gastropods and bivalves and right photo (core interval 1004.41-1004.75) molluscan packstone that has been partially dolotimized and micritzed upsection with partial to complete dissolution of mollusk shells.

Photomicrograph (B) shows dense micrite matrix (Mi) between grains and fine to granular sparry calcite

(SP) cement replacing intraparticle pore space. Allochems consist largely of benthic foraminifera

Elphidiidae (E), Ammonia sp. (A), and Miliolidae (M), mollusk shell fragments, and peloids (P) from micritized bioclasts. Facies has intraparticle porosity (stained blue). Photomicrographs was taken at core depth 1015.90 ft. in PPL at 2.5X magnification.

5.1.10 Lithofacies 10: Skolithos-Cruziana bioclastic-lithoclastic packstone to grainstone

LithoFacies 10 (Figure 22) is composed of yellowish grey (5Y 8/1) to light greenish grey (5GY 8/1) grainstone. Original sedimentary fabric has been destroyed due to extensive bioturbation (BI of 5 to 6) resulting in mottled fabric appearance. Grains include skeletal fragments, peloids (heavily micritized), benthic foraminifera, micrite intraclasts (1-2%), and minor amounts of cementing micrite. Grains range from mud to coarse sand size. Accessory minerals include abundant angular to subangular, very fine to fine quartz grains (40-50%) and fine sand to granule size phosphorite grains (1-3%).

Shallow to middle tier ichnofauna from the Skolithos and Cruziana ichnofacies are pervasive throughout the facies including: horizontal to oblique u-shaped

Rhizocorallium (Rh) burrows with spreite, vertical to oblique, pellet lined Ophiomorpha sp. (Op) burrows with passive fill, and horizontal, unlined Planolites (Pl), Scolicia(Sc) sp. burrows showing horizontal meniscate backfill structure. Cross-cutting relationships

between Ophiomorpha sp. burrows and Palaeophycus (Pa) sp., Palaeophycus sp.(possibly hebert) with horizontal to oblique burrow structure are common.

Figure 22. Lithofacies 10: Skolithos-Cruziana bioclastic-lithoclastic grainstone. Core photographs show

(A) (core interval 1030.75-1031.17 ft.) Rhizocorallium (Rh), Ophiomorpha sp. (Op), Planolites (Pl); (B)

(core interval 1026.70-1026.87 ft.) Scolicia(Sc) sp.; (C) (core interval 1022.75-1022.92 ft.) cross-cutting relationship of Ophiomorpha sp. burrow and Palaeophycus (Pa) sp.; (D) (core interval 1021.16-1021.33 ft.)

Palaeophycus sp.(possibly hebert); (E) (core interval 1022.00-1022.50) vertical and oblique Ophiomorpha sp.; lower burrow is truncated at the top by Nereites (Ne) sp? and cross-cut at the bottom by Thalassinoides

(Th) sp. Photomicrographs (F) shows angular to subangular quartz grains (white), moderately to poorly connected interparticle porosity (blue), micrite/organic matter (black), foliated and crenulated mollusk shell fragment (Pectinidae) (M) and foraminiferan (F). Photomicrographs were taken at core depth 1025.75 ft. in PLL at 5X magnification. Scale in centimeters.

5.1.11 Lithofacies 11: Quartz sand/silt to sandy bioclastic grainstone

Principle constituents present in lithofacies 11 have an angular to subrounded grain shaped, fine to silt size quartz grains rich in phosphatic sand (silt to fine), fragmented skeletal material and peloids (medium to coarse grain size) (Figure 23).

Peloids are micritized bioclasts; some bioclasts are have well defined micritic rims.

Sediment has minor to absent carbonate mud with little induration/lithification of sediment (loose sand). Color ranges from light gray (N8) to dark yellow brown (10 YR

4/2). Dark color is from high phosphatic sand content, 30% of total composition, and micritized allochems (30 % of composition). Grainstone of facies 11 has less phosphorite than sand to silt facies and an increase in micrite. Lithofacies has well connected interparticle porosity. Sediment of the lithofacies is poorly sorted.

Figure 23. Lithofacies 11: quartz sand/silt to sandy bioclastic grainstone. Top photomicrograph shows sand to silt of facies 11 with the main constituents being quartz (Qtz), phosphorite (Ph), peloids (P). Peloids are micritized bioclasts; some have dark micritic rims. Photomicrograph is stained blue to highlight void space, interparticle porosity. Bottom photomicrographs shows grainstone texture of facies 11. Grains include foraminifera (F), quartz, and peloids from micritized bioclasts surrounded by dark micrite.

Photomicrographs were taken at core interval 999.23 ft in PPL at 2.5X magnification.

5.1.12 Lithofacies 12: Whole molluscan skeletal floatstone

Lithofacies 12 is represented by a very light grey (N7) to light grey (N8) well cemented, molluscan skeletal wackestone to floatstone with a benthic foraminifera, micritic matrix (Figure 24). Micrite is the principle matrix component with 20-30% mollusk shells, 10% peloids, and 5% carbonate intraclasts. Grains size ranges from mud

(matrix) to pebble. Accessory grains include phosphorite grains (1-2%) and fine to very fine, angular to subangular quartz grains (5-10%). Core shows evidence of calcite neomineralization inside some shell molds creating dogtooth spar. Most shells have been dissolved resulting in moldic/intraparticle porosity. Fauna includes mollusks, gastropods, brachiopods (ostracods), and sponges. Cements include void filling/replacement intraparticle spar within aragonitic molluscan fragments and micrite cement which constitutes the matrix. Most moldic pores have been partially filled by calcite cementation resulting in well-developed moldic porosity and low associated permeability.

The facies contains two disconformities, one at the base and one at the top that are characterized by scoured surfaces, phosphitization, and karstification with subsequent backfill of voids with coarse material from above. Calcite void fill/replacement is 59

associated with fresh water diagenesis which includes the inversion of aragonite to calcite.

Figure 24. Lithofacies 12: whole molluscan skeletal wackestone to floatstone. Core photographs point to A) dissolved mollusk fragments (lower arrow) and whole mollusk shells (upper arrows) (core interval 1036.2- 60

1036.6 ft.), B) partially spar replaced gastropod (Turritela) shells (arrow) (core interval 1042.4-1042.9 ft.) and C) abundant cerithid (C) gastropods in wackestone to packstone. Photomicrograph (D) shows equate sparry calcite (SP) void fill/replacement within a leached mollusk shell fragment, ostracods (O), mollusk fragments (M), and angular to subanglular quartz (Qtz) grains suspended in a micrite matrix.

Photomicrograph was taken in plan- polarized light at 2.5X magnification at core depth 1041.15 feet. Scale in centimeters.

5.1.13 Lithofacies 13: Bioturbated carbonate sandstone

Lithofacies 13 (Figure 25) is a siliciclastic deposit with variable amounts of allochems and minor amounts of micrite cement between grains. Color ranges from light olive grey (5Y 6/1) to olive grey (5Y 4/1) to yellowish grey (5Y 8/1). Grains include angular quartz (>50%), skeletal fragments (10-15%) medium sand size phosphorite grains (15-20%), micrite intraclasts (average 1-2 % but localized 5-10%), and variable amounts of foraminifera, and organic material. Facies has well-connected interparticle porosity. Sedimentary bedding has been mottled from intense bioturbation. Intraclasts range from 2 mm to 1 cm in diameter and are typically irregularly shaped. Ichnotaxa include Terebellina, Ophiomorpha, Planolites, Rhizocorallium, Thalassinoides,

Phycosiphon and possibly Taenidium, but burrow structure is not well defined.

Figure 25. Lithofacies 13: Bioturbated carbonate sandstone. Core photographs showing (A) mixed carbonate/siliciclastic, sandy mollusk fragment grainstone/packstone deposit with well-preserved burrows of oblique to vertical Rhizocorallium (Rh) with meniscate backfill; oblique to vertical, pellet-lined

Ophiomorpha nodosa (Op); box work, unlined Thalassinoides sp. (Th) (core interval 1052.8-1052.2 ft.) and (B) branching and lobed meandering complex system of Phycosiphon sp. (Ph) burrows (core interval

1057.1-1056.4 ft.). Photomicrograph (C) shows dominate angular to subangular quartz (qtz) grains and allochems (A) including biserial foraminifera (F), skeletal fragments (Sf), and micritized (mi) grains.

Photomicrograph was taken in PPL at 2.5 X magnification. Scale in centimeters.

5.1.14 Lithofacies 14: carbonate sandstone

Lithofacies 14 (Figure 26) is a muddy, siliciclastic deposits with equal amounts of quartz sand and carbonate mud (micrite). Lithofacies 14 is similar to facies 13 but differs due to a larger amount of organics and less quartz grains. The facies has a mottled sedimentary fabric and is poorly indurated/weakly cemented (friable) with common molds or vugs at the base of the facies. Color ranges from light olive grey (5Y 6/1) to yellowish grey (5Y 8/1). Dominant grains are sand to silt sized, angular quartz grains with variable amounts of carbonate mud between clastic grains. Angular quartz grains account for approximately 50% of all grains. The grains are surrounded by heavily micritized allochems and few ostracods and foraminifera (Bulimiuidea?). Facies has poorly connected interparticle porosity. Lenses of abraded sand, shell, and phosphorite are common through the facies. Base of the facies grades upsection from lithoclastic conglomerate to a fine grained carbonate sandstone. The base of the facies appears scoured with large (5-6 mm), angular lithoclasts (rip-up clasts). There is an associated

increase in gamma ray activity for this section. The underlying lithofacies contains no phosphorite, indicating this in the last downhole occurrence of phosphorite since facies 2.

Based on the evidence above, this contact is the lithostratigraphic base of the Arcadia

Formation which is coeval to a sequence boundary. The sequence boundary is based off the evidence of erosion from scouring, significant change in grain size (increased GR activity), and a facies dislocation where the shallow-water sediments of lithofacies 14 lies unconformably above the deeper water facies below. The presence of ostracods in facies

14 indicates shallow water/lagoonal environments as well as the abundance of quartz grains which often accumulate in great quantities in lagoonal/restricted platform environments during sea-level low stands. The facies is restricted to the base of the formation.

Figure 26. Lithofacies 14: Phycosiphon carbonate sandstone. Photomicrograph of facies 14 showing large percentage of angular quartz (Qtz) grains (~50% composition) surrounded by heavily micritized (Mi) allochems (A), and few ostracods (O) and biserial foraminifera (FB). Facies has poorly connected interparticle porosity (P). Photomicrograph was taken at core interval 1060.90 ft. in PPL at 2.5X magnification

5.2 Sequence Stratigraphy

The main breaks between the facies associations in the stratigraphic succession were defined to compile a 1D sequence analysis of the Arcadia Formation in the G-2984 core (Figure 27). Each sequence stratigraphic system tract was defined based on lithofacies association stacking patterns and recognized sequence boundaries. A list of lithofacies and their associated system tract were given in Table 5.

Figure 27. Interpreted sequence stratigraphy of the Arcadia Formation in core G-2984 67

Arcadia Sequence 1 (ARS1) consists of one cycle that contains a shoaling upward lithofacies succession capped at the base and top by erosional unconformities. The base of ASR1 marks the base of the Arcadia Formation, and the top of the sequence is bounded by an erosional unconformity with evidence of dissolution and karstification, including microtopography. The top of ASR1 conforms to the criteria for a sequence boundary, as defined earlier. Sequence 1 contains no outer ramp facies, with deep inner ramp representing the deepest facies. The most abundant facies in the sequence is a carbonate sandstone and whole fossil molluscan floatstone. Lithofacies associations present in sequence 1 are shown in Table 5. The dominate facies in ASR 1 is a carbonate sandstone. This sequence is a lower part of the trangressive system tract (TST) of a higher magnitude depositional sequence with a general relative rise in sea-level.

Table 5. Sequences and cycles with lithofacies associations throughout the Arcadia Formation

Sequence Cycle Facies Stacking Sequence Cycle Facies Stacking Patterns (from bottom Patterns (from to top) bottom to top) ARS1 1 14, 13, 12, 1 ARS4 13 5, 2

ARS2 2 10, 9, 1 14 5, 2, 1

3 13, 11, 15 5, 2, 11

4 13, 11 16 5, 2, 1

5 13, 8, 5, 1 17 5 2, 1

ARS3 6 7, 5 18 9, 2, 1

7 7, 1 19 9, 2, 1

8 6, 5

9 6, 5

10 6, 4, 3

11 4, 3, 1

12 4, 3, 1

Arcadia Sequence 2 (ARS2) is characterized at the base and top by dissolution/karstification and calcrete formation respectfully. These characteristics suggest subareial exposure. No outer ramp facies are present in ARS2 and the dominant lithology is molluscan packstone to floatstone with well-developed interparticle porosity

(facies14). There are progradational and retrogradational cycle sets within the sequence, with the maximum carbonate production probably occurring during this period accommodation=accumulation).

Arcadia Sequence 3 (ARS3) contains thick cycles dominated by subtidal/deep ramp facies. This sequence represents the time of maximum flooding of the platform and the deepest facies deposited during that period of time. The maximum flooding surface within the sequence is marked by a “drowning unconformity” (Cunningham, 2013) that is characterized by a phosphatic hardground that is overlain by a fine-grained siliciclastic deposits and marks the transition from the TST to the RST.

The top of the Arcadia Formation is the bounding surface of Arcadia Sequence 4

(ARS4). This stratigraphic surface is a known erosional unconformity (Cunningham et al,

1998). It extends regionally and is easily recognizable based on physical changes in the rock record that marks a regional change of the deposition regime and sediment composition from mixed carbonate-siliciclastic to dominantly siliciclastic (regional carbonate demise and platform drowning). Physical changes are characterized by non- depositional, condensed intervals that are often contain phosphatic gravel and reworked sediment. These changes are also evident in wire-line gamma ray logs characterized as an increase in activity (gamma-ray spike). It was also found that the top of the Formation has a 2 – 8 my hiatus (Missimar, 2000; Guertin, 1998).Based on the criteria described above, the lithostratigraphic boundary defining the top of the Arcadia Formation coincides with a 3rd order depositional sequence boundary. The sequence boundary is overlain by quartz sandstone with shallow carbonate mudstone below. The sequence boundary itself is characterized by a thick phosphorite gravel deposit that is interpreted to have formed during a period of sediment starvation and nondepostition with later reworking during sea level low stands.

CHPATER 6

6.0 DISCUSSION

6.1 Paleoenvironments of Lithofacies

The interpretation of depositional environments of the Arcadia Formation was based on the general idea of a carbonate ramp to platform environment that contains supratidal, intertidal, and deep/restricted lagoon (restricted marine environments), open open lagoon/subtidal and sand barriers/shoals (platform environments), shoreface and foreslope (inner ramp), and clinothem, open shelf, and deep shelf (outer ramp) depositional environments (Figure 28). The dominant skeletal components of most lithofacies are planktonic (globigerinids) and benthic (miliolids) foraminifera in varying abundances and in association with other skeletal constituents such as mollusks, gastropods, pelecypods, echinoderms, and ostracods. Most lithofacies contain an abundant amount of micrite, which is typical for ramps that contain large, protected environments (Algner, 1985). The depositional environment of each lithofacies was interpreted based on similar characteristics including sediment type, grain size, cement, texture, flora and fauna assemblages, sedimentary structures, and biogenic structures.

Lithofacies associated with each depositional facies are discussed below.

Figure 28. Cross section of interpreted carbonate ramp depositional environments of the Arcadia Formation showing distribution of interpreted lithofacies. Facies area indicated by the numbers at the top of the figure.

6.1.1 Restricted lagoon environment

Lithofacies 2, 4, 5 and 8 are interpreted to belong to the restricted lagoon to intertidal environment that is protected from dominant wave energy. The environments include Glossifungites claystone to mudstone (lithofacies 2), peloidal, bioturbated wackestone (lithofacies 4), sandy wackestone-packstone (lithofacies 5), and moldic packstone (lithofacies 8). Lithofacies 2 contains intense bioturbation from the

Glossifungites ichnofacies including Thalassinoides along with Palaeophycus and

Skolithos ichnotaxa. Bioturbated mudstones are common in shallow, lagoonal environments (Wilson, 1975) and a high density of Thalassinoides burrows, which are part of the Skolithos ichnofacies, is indicative of bays and lagoons (Gerard and Bromley,

2008). The Skolithos ichnofacies colonizes intertidal to shallow marine environments, above normal wave base (Buatois and Mangano, 2011). Based on the criteria list above, facies 2 was deposited in a shallow lagoon environment. 72

Facies 4 also contains prevalent Palaeophycus burrows which are indicative of a lagoonal environment (Gerard and Bromley, 2008). Based on the abundance of peloids, micrite, and Palaeophycus ichnotaxa, facies 4 was deposited in a lagoon or shallow intertidal pool. Bedding has been poorly preserved due to ichnofaunal activity. Peloids are formed in a protected shallow water environment with minimal sub-sea cementation

(SEPM STRAT, 2013).

Lithofacies 8 is a moldic packstone to wackestone including skeletal grains of gastropods and mollusks, peloids (micritized bioclasts), shell fragments, and planktonic foraminifers (globigerinids). Lithofacies 8 was interpreted as being deposited in a restricted lagoon to subtidal environment based on a lack open marine fauna, micritized bioclasts, and carbonate mud. Lithofacies 5 is interpreted to belong in the intertidal range due to the abundance of fine-grained, winnowed sand present in the facies. However, since micrite was one of the principle components, the sediments are interpreted to have been deposited in a low energy environment.

6.1.2 Open shelf lagoon

Lithofacies 3, 10, and 12 are interpreted to be open shelf lagoon depositional environments (open platform). This are is defined is located behind the outer platform edge with generally shallow water depth (tens of meters). Sediment types associated with the environment include peloidal packstone to grainstone (lithofacies 3), Skolithos-

Cruziana bioclastic to lithoclastic packstone to grainstone (lithofacies 10), and whole molluscan skeletal floatstone (lithofacies 12). Lithofacies 12 contains whole shell

gastropods suspended in micrite with variable sparry calcite cement. Gastropod-ostracod wackestone and packstone with quartz has been found to characterize restricted marine and lagoonal/deep lagoonal environments in the Suwannee shallow-water carbonate ramp

(e.g. Ursula 1992; Hardle and Shinn, 1986) (

Table 6). The high spired gastropods Turritella and Cerithidea are common in lithofacies 12, indicating a water depth of less than 200 meters and were common in shallow lagoon environments during the Oligocene (Ursula, 1992). Recent living cerithid gastropods are common in nearshore, restricted, lagoonal environments in the Bahamas and Florida Bay (Multer, 1977). Cerithid shell fragments are associated with channel deposits, sorted by tidal currents, and subtidal deposits that have been transported by storms or waves (Garrett, 1977). Most of the cerithid gastropods found in lithofacies 12 are whole-shell gastropods suggesting a lower energy environment such as a lagoon. A significant proportion of micrite and organic material supports a restricted/ lagoonal environment interpretation. Lithofacies 12 is also characterized by diagenetic sparry calcite cement or dogtooth spar which is the result of calcite mineral precipitation through mobilized mineral saturated waters resulting from meteoric interactions with calcium carbonate.

Lithofacies 10 has an ichnofaunal assemblage that belongs to the Skolithos ichnofacies (with Ophiomorpha burrows) and the Cruziana ichnofacies (with

Thalassinoides and Rhizocorallium burrows) along with rare to common Scolicia,

Palaeophycus, Planolites and Nereites (?) burrows. Large 2 to 6 cm diameter vertical and horizontal burrow systems indicate higher energy, shallow inner ramp facies (possibly 74

upper to middle shoreface). Ophiomorpha burrows in the Miami Limestone are characteristic for a stabilized sand flat at very shallow depths (Halley and Evans, 1983).

Grains in this facies also appear to be winnowed, containing little mud. The occurrence of large, angular intraclasts at the base of lihtofacies 10 suggests erosion from submarine channels that are common in open marine lower to upper slope deposits. The facies has common diagnostic characteristics: 1) compete destruction of sedimentary fabric from heavy bioturbation, 2) mixed carbonate and siliciclastic components as well as a paucity of open marine fauna, 3) presence of little carbonate mud, and 4) colonization of open marine lower shoreface ichnotaxa: Ophiomorpha nodosa, Phycosiphon sp.,

Thalassinoides sp., and Rhizocorallium sp. that indicates a shallow marine open platform/subtidal environment (Gerald and Bromley, 2008)

Table 6. Profile across the subjacent Suwannee shallow-water carbonate ramp displaying the dominant occurrence of grains, depositional texture, and depositional

structures across subenvironments (modified from Ursula, 1992).

6.1.3 Inner ramp environment

The inner ramp depositional environment includes lithofacies 9 (bioclastic grainstone to floatstone), 11 (quartz sand/silt skeletal fragment quartz sand), 13

(Rhizocorallium Sandy mollusk fragment sandstone), and 14 (Phycosiphon carbonate sandstone). The inner ramp is defined as the area above to slightly below fair-whether wave base. Water depth is generally shallow (<20 m deep) with moderate to low wave energy and open circulation (Wilson, 1975). During maximum regression, this facies may be subareially exposed, developing karstification.

Lithofacies 9 (bioclastic wackestone to floatstone) contains bioclasts support in a micrite matrix. Allochems including benthic foraminifera skeletal fragments, and intraclasts. The facies grades to a pelecypod floatstone directly below an area of phosphatization and/or dolomitization. Based on the characteristics described above, the facies belongs to a moderate energy, open platform environment where shells are built-up into bioherm mounds. However, organic coral reef complex is missing from this facies.

Lithofacies 11 has large mollusk shells along with an abundance of fine-grained, muddy quartz sand. Missimer (2002) identified a similar facies within the Arcadia

Formation on the west coast of Florida and interpreted it to be an inner ramp facies.

Lithofacies 13 and 14 are a siliciclastic deposits that have been heavily bioturbated.

Prominent vertical and horizontal burrows are easily recognizable. Ophiomorpha nodosa and Rhizochorollium are prominently within facies 13. These ichnotaxa typically colonize surfaces in higher-energy marine environments (Gerard and Bromley, 2002).

Based on the ichnotaxa present and the winnowed nature of the grains, lithofacies 13 is 78

interpreted to be a shallow inner ramp environment. Lithofacies 14 contains more mud and is dominated by Phycosiphon which is indicative of deeper marine waters (Gerald and Bromley, 2008). Based on the additional mud content and shallow to deep marine ichnotaxa, facies 14 is deep inner ramp.

6.1.4 Outer ramp environment

Lithofacies belonging to an outer ramp depositional environment include: 6

(cherty carbonate mudstone) and 7 (molluscan shellbed floatstone). The outer ramp is defined as the area in the open shelf just below the storm wave base and landward of the basin. Water depths range from tens to hundreds of meters, deep enough to be below normal wave base. Marine waters are generally well oxygenated and have normal salinity. Lithofacies 6 is an interbedded claystone and mudstone facies that is non- laminated to poorly defined planar laminations and lacks open marine fauna. Bedded and nodular black concretions believed to be chert are common along the bedding planes. A hardground marks the lithologic transition from almost pure terrigenous claystone to a carbonate mudstone. Burrows and hardground have undergone silicification and localized phosphatization. Marine phosphorite diagenesis is associated with shallow restricted shelf or platform environments in water depths ranging from 50 to 200 meters (Miller, 1982).

There is no evidence of an exhumed surface above the contact. The Arcadia Formation has been found to contain chert, opal-CT, and has been commonly associated with silicified clays and dolosilts (Scott, 1988). Based on 1) the presence of Palaeophycus, which commonly occurs in marginal to fully marine depositional environments (Gerald and Bromley, 2008), 2) the dark brown organic lamina, and 3) chert nodules, lithofacies 6 79

interpreted to represent a deep shelf environment, landwards of the basin in an environment of restricted water circulation. The cessation of deposition allows the sediment-water interface to remain in an appropriate environment to allow for phosphogenesis to occur within and around burrows (Dickinson and Wallace, 2009).

Lithofacies 7 is characterized by the occurrence of the open water pelecypod

(Hyotissa) mollusk that has an absolute water depth range between 20 and 40 meters

(Missimer and references therein, 2002). The facies is capped by a phosphatic gravel

(discontinuity surface) that suggests an environment of slow sedimentation to allow for the accumulation of a phosphatic crust. Based on the high percentage of carbonate mud filling void spaces, facies 7 was mostly deposited in a shallow outer ramp environment.

6.2 Regional Correlation of Sequence Boundaries

The Arcadia Formation located on the southernmost platform margin (Florida

Keys) was found to be a composite sequence composed of four high-frequency sequences and multiple higher-frequency cycles (Cunningham et al., 1998). Within the study area for Cunningham et al‟s (1998) study, the base and top of the formation was discovered to be bounded by major, third-order sequence boundaries which separate the sediments of the Arcadia Formation from the underlying Suwannee Limestone and the overlying Peace

River/Stock Island Formations. The hiatus between the Suwannee Limestone and Arcadia

Formation has a considerable regional variation in south Florida, ranging from ~ 2.0 m.y. at the platform interior (Missimer, 2002) to 8.1 m.y. at the southern platform margin

(Guertin et al, 2000). The variation in the duration of the hiatus can be accounted for by the regional separation of the study areas for Guertin et al (2000) and Missimer (2002).

The time difference between the two disconformities was probably influenced from paleotopographic variations that resulted in a longer period of erosion and/or nondeposition at the southern margin.

In the western interior, this sequence of sedimentary packages below the sequence boundary defining the top of the Arcadia Formation shows an irregular shoaling upward stacking pattern (Missimer, 2002). The majority of siliciclastics present in the Arcadia

Formation occur directly below this sequence boundary. The overlying Formations,

Peace River in the north and Stock Island/Long Key in the south are progressively more siliciclastic. The hiatal duration between the Arcadia Formation and the overlying siliciclastics ranges from approximately 4 m.y. north of the Florida Key to almost 11 m.y. at the southern edge of the Platform on Stock Island (Guertin, 2000).

The Arcadia Formation consists of two third-order sequence boundaries which enclose multiple higher-order, lower magnitude sequences. The vertical lithofacies succession in the core was correlated to gamma ray wireline logs to determine representative gamma-ray signatures and their implications in the stratigraphic framework. This allowed for the establishment of a 2-D sequence stratigraphic interpretation that utilized gamma-ray signatures to help correlate between core wells.

High gamma-ray activity correlated well with surfaces of discontinuity that often have accumulations of high radioactive material such as phosphatic crusts and phosphorite gravel. These surfaces of higher increased gamma ray activity correlated well with 81

previously identified high-frequency sequence boundaries (Figure 29) from Cunningham et al„s (1988).study of the Arcadia Formation in the Florida Keys region.

Figure 29. Cross section of Arcadia Formation showing regional correlation of sequences and sequence boundaries. Wells with an asterisk indicate previously identified sequences from Cunningham et al (1998).

CHAPTER 7

7.0 CONCLUSION

Based on the interpreted depositional environments, sediments of the Arcadia

Formation were deposited on a carbonate ramp to platform setting in approximately 10 to

100 meters of water. The characteristic phosphorite deposits that define the top of the formation and SB formed from nutrient-rich marine upwellings that resulted in extensive phosphate deposition over the carbonate platform. A large hiatus in sediment deposition ranging in duration from 4 m.y. to 11 m.y. is present between the top of the Arcadia

Formation and the base of the Peace River Formation (Cunningham et al., 1998; Guertin,

2000). However, no direct evidence of subaerial exposure was present in the G-2984 core; but a firmground, glossifungites ichnofacies colonized by Thalassinoides sp. exists directly below the boundary indicating a period of non-deposition and erosion. The

Glossifungites burrows within the Arcadia Formation are associated with firmground substrates. These substrates are firm but not lithified intertidal and shallow marine sediments that have been exposed to the sediment-water interface from scouring and erosion. The surface where the SB for ARS1 exists is interpreted to represent a transgressive surface that formed following a regression and sea level fall and just after the initial transgressive phase immediately following sea level lowstands.

Erosion associated with sea-level lowstands may have removed the lowstand system tract sediments allowing the transgressive surface (TS) to be coeval with the SB.

This research resulted in the identification of fourteen sedimentary facie, ranging from mudstone to grainstone. Regional analysis revealed that the major SB that defines the top of the Arcadia Formation can be correlated south to the Florida Keys with good accuracy and the minor, higher-frequency SB „s of the third-order sequence can be correlated confidently using gamma-ray signatures from well G-2984 southward to well

DF-1. Correlation of minor (lower magnitude, higher-frequency) SBs in wells south of

DF-1 are estimated and less confidently determined. Lithologic characteristics change from south to north, transitioning from wackestones, packstones, grainstones, rudstones, and dolostones south to thick mudstones and claystones in the north. The vertical transition from the lower section to the upper section can be distinguish on gamma-ray logs as an increase from low activity to very high, sporadic activity.

Four higher-frequency depositional sequences were identified within the major third-order sequence that spans the entire Arcadia Formation. Each sequence contained a series of vertical lithofacies association that allowed for the interpretation of an evolving paleodepositional environment for each sequence. ARS1 is located at the base of the formation and is composed of a mixed carbonate-siliciclastic lithofacies association, representing the highest-energy depositional environment within the Formation. High gamma-ray activity within the sequence reflects the large percentage of phosphatic sand present and high sonic lag activity reflects the larger amount of siliciclastics present within the sequence. ARS2 is similar to ARS1 and is composed of mostly grainstones 84

and packstones. The interpreted depositional environment of ARS2 is open platform to open lagoon/edge of platform. The sequence boundary separating ARS2 from ARS3 is a drowning unconformity marking a large influx of siliciclastic clays into the platform.

ASR1 and ASR2 can be considered part of the informal lower Arcadia Formation. The lower section of the Arcadia Formation can be considered to be part of the Upper

Floridan Aquifer system as it has similar lithologies and well developed, interconnected, interparticle and intraparticle porosity.

There is a distinct lithologic difference between the lower and upper parts of the

Arcadia Formation. The lower part of the Arcadia Formation is extends from the base of the formation at 1065 feet BLS to 924 feet BLS, having an approximate thickness of 141 feet. Whereas the upper part of the Arcadia Formation has a thickness of approximately

332 feet, extending from 954 feet BLS to the top of the formation at 592 feet BLS. The difference in sediment composition can be explained by the difference in depositional environments. The upper part of the Arcadia Formation was deposited in low-energy, restricted platform/inner platform and deep outer ramp environments and the lower part in higher-energy inner the shallow outer ramp environments. The upper Arcadia

Formation differs in lithology from the lower Arcadia Formation, being composed of predominantly mudstones, claystones, and wackestones. The upper section of the Arcadia

Formation is interpreted to be part of the intermediate confining unit of the Floridan

Aquifer System. The fine-grained lithology and poorly developed porosity is consistent with that of a confining unit. The informal upper Arcadia Formation is G-2984 was composed of two sequences: ARS3 and ASR4. ARS3 represents that period of maximum

flooding over the platform; containing the maximum flooding surface (MFS) that separates the TST from the RST in the third-order system tract. The depositional environment of ARS3 is outer ramp to deep shelf with few open platform facies. ARS4 represents the period of lowest sea-levels and is dominated with intertidal and restricted platform sediments. ARS4 is also heavily colonized by cruziana and glossifungites ichnofacies.

Very few ichnologcial studies have been conducted on the Arcadia Formation, and there has been no published literature addressing regional correlations of ichnofacies present between boreholes. Further investigates into the ichofossil assemblages within the

Arcadia Formation using continuous core can provide more hydrodynamic and paleoenvironmental data for a more accurate reconstruction of sea-level change over the

South Florida Platform during the Oligocene to Miocene.

Additionally, this research was done over the course of two years and only at one sample site. Expanding the data set to include more boreholes and a longer period of time could result in a better, more accurate regional correlation of sequence boundaries and ichnofacies within the Arcadia Formation. This could potentially aid future predictions of

Sedimentological variation between boreholes within the Arcadia Formation.

APPENDIX

Lithologic description of the Arcadia Formation interval of test core G-2984 including physical sedimentary structures, biogenic structures, biota, and

ichnotaxa present.

Appendix Table 1

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 592.3 593.0 Phosphate Black Pebble Unconformity related deposit

87 to

cobble 593.0 605.8 Wackestone Pale mud to Minor amount of phosphatic sand (1-3%) and minor phosphate Planolites to lime greenish fine granules (1-2%). Amount of phosphate increases downwards. Chondrites mudstone yellow Calcrete layer right below phosphate gravel extending to a Phycosiphon depth of 598 feet. Horizontal to oblique burrows with passive fill similar to host sediment. Top half foot of interval contains burrows backfilled with coarse bioclastic-lithoclastic, phosphatic sediment that are Thalassinoides burrows.

Appendix Table 1 con't 1

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 605.8 621.0 Lime Pale Mud Surface of erosion at top of interval overlain by pebble-sized Thalassinoides mudstone olive intraclasts and granular- to pebble-sized phosphate grains supported in a micritic matrix. Bivalve borings in hard, cemented rock penetrating 3 cm below contact. Fragment of possibly boring bivalve (mollusk) in situ. Half a foot below contact, extensive burrowing of sediment with coarse, phosphatic, granular backfill and with carbonate halos around burrows. Burrows are unlined. Coarser backfilled burrows cross-cut smaller, deeper tier burrows indicating

burrowing and erosional event were syndepositional.

Appendix Table 1 con't 2

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 621.0 623.8 Packstone Pale Fine to Bioclasts include mollusk shell fragments and shell hash and coral olive very fragments. Lithoclasts include granular phosphate and darkened coarse carbonate intraclasts. Moldic and vuggy porosity.

623.8 630.8 Wackeston Very Very Minor amounts of phosphatic (1-3%) and quartz (3-5%) sand. Ophiomorpha e pale fine to Moderately bioturbated. Small (1-2 mm) and large (5-6 mm) Chondrites orange fine horizontal to oblique burrows. Some burrows are unlined while others are lined. Passive fill similar to host sediment. 630.8 641.0 Lime Pale Clay to Massive bedding with phosphatic (1-3%) and quartz (1-3%) sand. Thalassinoides

89 mudstone olive silt Substrate gradation from a soft- to soupground to a firmground dominated

represented by zero to low compaction of burrows and sharper boundaries. Solitary phosphate gravel (2.5-3 cm diameter) at 639 feet possibly from above and dislodged during drilling. No evidence to support phosphatic gravel accumulation. Horizontal to oblique burrows; some have coarser sediment backfill and some have similar lithologies to host sediment.

Appendix Table 1 con't 3

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 641.0 650.5 Wackestone Pale Clay to Small (<1 mm) molds and shell hash surrounded by micritic Ophiomorpha to lime orangeish fine matrix. Phosphatic (1-3%) and quartz (3-5%) sand. Desiccation Zoophycos mudstone yellow (shrinkage cracks) from 645.25-646.75 feet (from dewatering due to coring?).Minor amounts of granule-sized phosphate and darkened carbonate grains. Horizontal to oblique, mottled burrows with passive sediment fill similar to host sediment. Some burrows have lined walls. Few burrows with spreite to meniscate backfill.

90 650.5 655.3 Lime Pale olive Mud Silt-sized phosphatic sand (1-3%). Top half foot of interval Thalassinoides

mudstone silt possibly has increased lithification of sediment represented by Planolites low to uncompacted burrows and sharper boundaries suggesting substrate gradation from a softground to a hard- or firmground. Horizontal to oblique burrows with passive sediment fill similar to hot sediment along with mottling. 655.3 658.5 Wackestone yellowish silt to Phosphatic (10%) and quartz sand with some granule phosphate grey very (3%). Finning upwards trend. Burrows walls become more fine sharply defined at top of interval suggesting firming of substrate, possible firmground conditions. Zero to poor bioturbation. Horizontal to oblique burrows that are poorly preserved.

Appendix Table 1 con't 4

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 658.5 668.0 Mud to loose Light Clay to Loose, unconsolidated phosphatic (30%) and quartz sand with Zoophycos sand olive silt to carbonate mud. Some areas are better lithified than others with grey very some biogenic structures preserved. Horizontal to helical spreite fine boarded by a narrow, darker colored wall lining. sand 668.0 678.0 Micrite Light Clay Moderately bioturbated. Less than 1 % phosphatic sand. Wavy to Phycosiphon olive planar laminations reflected as color banding caused by Zoophycus grey concentrations of clay. Most bedding has been totally destroyed Planolites

91 due to bioturbation. Increasing phosphatic sand and quartz sand

upwards. Interval of high phosphate and coarse material at 674.9- 674.5 feet. Horizontal and oblique burrows with passive fill similar to host sediment. Some burrows are backfilled with coarser sediment. Burrows are poorly preserved.

678.0 694.0 Wackestone Light Clay to Phosphatic (5%) and quartz (5%) sand. Some vugs or molds that Plantolites? olive fine appear to be filled with phosphate. Moderate to poorly bioturbated. Thalassinoides grey Horizontal and oblique burrows with passive fill similar to host Chondrites? sediment. Some burrows are backfilled with coarse, sandy Phycosiphon phosphatic grainstone with burrows poorly preserved.

Appendix Table 1 con't 5

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 694.0 697.0 Floatstone yellowish silt to Large (>2 mm) phosphate (5%) and dark brown carbonate grey fine lithoclats. Matrix consists of micrite and microscopic shell sand- hash of gastropods and mollusks. Contact at 694 feet where sized non-bioturbated sediment is overlain by moderately bioturbated sediment. 697.0 701.8 Mudstone/ light olive clay to Calcrete nodules and rip-up clasts at top of interval (697 feet). Scolicia micrite grey silt Bedding has been disrupted by bioturbation, but some parallel Phycosiphon laminations remain. Dolotimization of limestone ; slow

92 reaction to HCl. Percent clay decreases downward.

Horizontal to oblique burrows with similar passive and contrasting fill to host sediment. 701.8 712.0 Marl/mudstone yellowish clay to Planar-bedded lime mudstone with even mm laminae. grey silt Laminae are reflected as color banding caused by concentrations of minor amounts of clay. Some wavy laminae. Minor amounts of phosphatic and quartz sand (1- 2%). Fast reaction to HCl from 701.75 to 707.75 feet. Interval from 701.75 to 707.75 is a marl/marlstone possibly interbedded with very fine sand. Gradual transition downwards into a wackestone as component grains increase. Loss of sample at 701.75 feet.

Appendix Table 1 con't 6

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 712.0 722.0 Wackestone pale Clay to Finning-upwards trend. Moderately phosphatic (15-20%) and rich greenish fine with quartz sand (20%). Allochems include shell hash and gray sand- darkened carbonate grains. Sediment is moderately bioturbated. sized Horizontal to oblique burrows with passive sediment fill similar to host sediment. Some burrows show mottling. 722.0 727.0 Floatstone Yellowish very Bioclastic floatstone with minor (1-3%) phosphatic sand. Matrix grey fine consists of micrite. Bioclasts are dominantly molluscan fragments sand to and benthic, disk-shaped forams. Some molds of mollusk and

93 clay gastropod shells. Top of interval has pebble-sized shells

fragments; some have been filled with calcite. Phosphate pebbles at top of interval. Horizontal and oblique burrows with passive fill similar to host sediment. Burrows are not well defined and unambiguous. 727.0 735.5 Peloidal White very Bioclasts and lithoclasts supported by a micritic matrix. Bioclasts packstone fine include granule-sized coral fragments and shell hash. Lithoclasts (matrix) include carbonate rock fragments and some granule sized to phosphate. Phosphatic sand (3-7%) and quartz sand (3-7%) granule present. Vuggy to moldic porosity. 735.5 743.0 Packstone White fine to Poorly indurated and friable. Allochems include shell hash, medium pellets, and lithoclasts. Phosphatic sand (<1%). sand

Appendix Table 1 con't 7

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 743.0 745.9 Rudstone White very Bioclasts and Lithoclasts supported by a micritic matrix. Bioclasts fine include coral fragments and shell hash. Lithoclasts include (matrix) carbonate rock fragments and some granule-sized phosphate. to Phosphatic sand (3-7%) and quartz sand (3-7%) present. coarse 745.9 750.0 Packstone White fine to Poorly indurated and friable. Allochems include shell hash, medium pellets, and lithoclasts. Phosphatic sand (<1%). sand-

94 sized

750.0 762.0 Wackestone yellowish very Bioclasts and lithoclasts supported by a micritic matrix. Bioclasts grey fine to include coral fragments and shell hash. Lithoclasts include medium carbonate rock fragments. Large bivalve shell (2 inches long) at sand- 759 feet. Sediment has been completely bioturbated. Phosphatic sized sand (1-2%) and quartz sand (1-2%) present. Biogenic structures include indistinct burrows. 762.0 765.7 Wackestone Yellowish silt to Coarsening-upwards trend and contains phosphatic sand (1-2%). grey to very pale fine greenish grey

Appendix Table 1 con't 8

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 765.7 787.0 Lime Yellowish clay Coarsening-upwards trend. Mostly massive but some faint mudstone grey to laminations. Phosphatic sand (1-2%). pale greenish grey 787.0 806.0 Calcareous Yellowish clay Massive bedding with minor, small (1-2 mm diameter) chert

claystone grey to nodules. Increasingly micritic upwards. 95

pale

greenish grey 806.0 815.5 Lime Pale clay Gradational contact from wackestone-packstone to fine mm algal mudstone to greenish laminated wackestone with variable amounts of clay. claystone yellow Differential chert nodules along clay-rich zones. Low density rock. Some phosphatic sand (1-2%).Top of interval is an erosional surface with microtopography and phosphitization. Elevation change of 3-4 mm. 815.5 824.5 Packstone to Pale fine to Finning upwards trend. Phosphatic (10 %) and quartz sand (10 wackestone greenish coarse %) rich packstone with slow and complete bioturbation of the yellow to sediment. Phosphatic and quartz sand decrease upwards. yellowish Biogenic structures include indistinct burrows. grey 95

Appendix Table 1 con't 9

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 824.5 840.9 Lime Pale clay to Planar-bedded lime mudstone with cyclic thickening and mudstone greenish fine thinning of laminae. Laminae reflected by color banding caused to yellow by concentrations of darker colored organics and lighter colored claystone clays. Differential chert nodules (1-5mm diameter) concentrating in clay-rich layers. Top of interval is capped by possible firmground.

840.9 878.5 Lime Yellowish clay to Planar inter-bedded lime mudstone and claystone. Top 0.2 feet

mudstone grey silt fine of interval contains a carbonate conglomerate channel fill with 96

to sand subangular to subrounded lithoclasts of carbonate rock and calcareous coarse to medium sand-sized phosphate and quartz grains. claystone Channel fill interrupts fine-grained, planar bedded sediment. Planar chert nodules become more abundant and increase in size upwards. Chert darkens in color upwards to black and becomes slightly vitreous (possibly grading in to flint). May indicate more organics or lower oxygen levels during sediment deposition. 878.5 885.8 Packstone yellowish silt to Differential chert precipitation in the form of nodules (3mm- grey fine 2cm diameter). Some nodules are dark grey to black while sand others are yellowish grey. Finely (1-2 mm) planar, micrite- packstone laminations. Phosphatic (approximately 5 - 10 %) and quartz (5-10%) sand. Surface of erosion at top of interval (878.5 feet);has microrelief of 3-4 mm. 96

Appendix Table 1 con‟t 10

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 885.8 907.2 Lime pale olive clay to Planar, even-bedded mm laminae where rock grades into lime mudstone very mudstone. Lighter layers are claystone. Some isolated chert to fine silt nodules (1-2 mm) in claystone. Upper 0.5 feet laminations calcareous become thicker and coarser (silt to very fine sand-sized). Large claystone (2.5 cm diameter) structure (possibly a horizontal burrow) with coarse bioclastic-lithoclastic calcarenite sediment fill at 897.4 feet. Grades into dominantly calcareous claystone at 899.9 feet. Chert nodules become more abundant upwards.

97 907.2 920.7 Lime Light Clay Planar, fine mm, interbedded lime mudstone and calcareous

mudstone greenish claystone. Slow hydrochloric reaction indicating a higher to gray percentage of silica than carbonate. Conchoidal to irregular calcareous fracturing of rock. Differential chert (dark blue to grey) claystone cementation and chert nodules in high-silica zones (claystone). Interpreted as mineral leaching from silicate clays, possibly chert preferentially developed along the burrow walls and infilling burrows. Top of interval has intense silicification and preservation of soft sediment structures. Largest burrow is 10 mm in diameter and walls are lined. Digenesis of chert appears to have outline burrows.

Appendix Table 1 con't 11

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 920.7 924.0 Lime Greenish mud Planar, interbedded, 1-3 cm laminae of lime mudstone and mudstone grey claystone. Fissile, appears to be breaking along bedding planes. to Zones of lime mudstone have planar, fine mm laminae and zones of claystone claystone with chert nodules (2 mm- 3 cm diameter). Chert is dark blue to black reflecting low oxygen levels during time of deposition and appears to only occur in layers of siliceous material (claystone). Planar bedded nature of chert indicates some digenetic enhancement of chert may have occurred post deposition. Beds of

claystone thicken upwards. 98

924.0 927.5 Oyster white to Clay to Phosphate nodules at top of interval that caps a layer of calcrete. shell bed light grey pebble Intense phosphitization and brecciation for about half a foot below. to black Oyster shell hash is surrounded by a micritic matrix. Shell debris is exclusively of bivalves 927.5 930.0 Dolosilt Light fine to Lack of any distinct bedding and numerous discrete burrows Possibly olive silt suggest soft- to soupground conditions. Indistinct burrows at base Thalassinoides grey to of interval. Burrow wall boundaries become sharper towards the pale top of the interval with little compaction. Fill is massive and similar yellow to host sediment. Burrows are horizontal to oblique. brown

Appendix Table 1 con't 12

Core Depth Lithology Color Grain Size Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals 930.0 938.8 Oyster Shell white mud Fossil mollusks that have been bored by marine invertebrates. bed (oyster (matrix) to Surrounding micrite sediment was syngenetically lithified by shells) pebble either micritization or void cementation. Bioclasts include to (oyster whole shell oysters.. yellow shells and brown shell (matrix) fragments) 938.8 944.0 Packstone to Phosphatized caliche crust at the top of the interval indicating Thalassinoides

99 wackestone subareial exposure and accumulation of organic matter. Interval Phycosiphon(?)

grades from a packstone at base to wackestone at top of Chondrities interval. Large (4 mm diameter) carbonate lithoclasts and abundant quartz grains (20 - 15%) and phosphate (10%).Molluscan molds (1-2 mm long) that are not interconnected. Some gastropod molds and casts. Sediment is contorted due to extensive burrowing. Intragranular fracturing on some lithoclasts. Indistinct unlined burrows at base of interval. Burrows become more sharply defined upwards due to firm consistency during emplacement. Burrows are 5 - 6 mm in diameter, horizontal to oblique with passive fill similar to host sediment.

Appendix Table 1 con't 12

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 944.0 949.9 Sandy yellow very fine Moldic packstone with some shell bioclasts. Large shells of mollusks Packstone grey to to up to 4 cm long and few casts. Large (3-4 cm) patches of poorly patches patches sorted, coarse sandstone that contains very coarse quartz grains, of light of carbonate lithoclats, and phosphate gains. Patches may be large olive medium burrows that have been backfilled with passive contrasting sediment grey to coarse (may be erosional sediment). Possible root molds at 947.3 feet. sand Large burrows with coarser-grained passive fill? Root structures at 943.7 feet?

100 949.9 954.7 Floatstone yellow very fine Increase in micrite matrix and decrease in clastic grains upwards.

grey to Large (coarse- to pebble-sized) bioclasts of mollusk and gastropod

pebble shells along with molds. Increase in dissolution of shells at top 0.3 (shells) feet of interval suggestive exposure to meteoric water. Possible erosional surface at 949.9 feet. 954.7 960.0 Packstone yellow very fine Finning upwards trend with an increase in micritic matrix upwards. grey to Phosphate and quartz grains (10 - 20 %) are abundant at base of medium interval and decreases upwards. Mottled appearance from bioturbation and some small moldic pores (1-2 mm). Quartz grain decrease upwards. Indistinct burrows.

100

Appendix Table 1 con't 14

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 960.0 965.0 Wackestone light mud to Poor recovery and broken pieces of PVC pipe also recovered. to micrite grey very fine 965.0 973.0 Sandstone light fine to Finning upwards trend with increase percentage of micritic grey very matrix upwards. Phosphatic (20 - 30 %) and high percentage of fine quartz grains (>50%). Some molds (1-2 mm long) of mollusk shells. Few lithoclasts and bioclasts including mollusk shell fragments and carbonate rock fragments.

101 973.0 983.0 Sand light silty to No recovery. Phosphatic (20 - 30 %) sand and large volume of

grey find following sand was recovered (according to driller). sand 983.0 1003.0 Sandy Dark sand to Alternating layers of light grey, poorly indurated floatstone to floatstone to yellow- pebble sandstone and dark grey, loose, quartz rich sand. Bottom two feet Sand brown of interval is dark yellow-brown. Matrix of floatstone is to light composed of micrite (30%), quartz (10-30%) and phosphate (10- grey to 30%). Large (2-3 cm long) degraded shells and smaller shell dark fragments floating in micrite matrix. Darker color of sediment is grey due to high percent of phosphate present. Sand intervals are highly phosphatic, containing 40-50% phosphate. Homogenization of floatstone sediment due to complete bioturbation. Poorly defined, elongated, indistinct burrows in floatstone.

101

Appendix Table 1 con't 15

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 1003.0 1005.6 Floatstone light very Darkening upwards trend possibly due to diagenetic changes grey fine to and/or phosphatization. Matrix consists of micrite with floating pebble medium- to coarse-sized bioclasts and lithoclats. Lithoclasts are carbonate grains, quartz, and phosphate. Molds become very distinct and commonly lined with calcite crystals (possibly indicating dissolution and reprecipitation of calcium carbonate

due to exposure to meteoric water). Possibly lag deposit at top 102

of interval.

1005.6 1018.8 Fossiliferous white to mud to Sticky, dark sand from 1017.7-1018 feet (possibly from Floatstone very very drilling?).Cementation/induration increases upwards. Abundant light fine molds and shells of mollusks (0.5 cm. to 2 mm. long) along grey with some vugs creating good moldic porosity. Molds become better connected upwards. Few casts of mollusk shells present and shell size increases upwards. 1018.8 1020.5 Sandy yellow- Fine to Finning upwards trend from a sandy packstone to wackestone. Wackestone grey at very Percent quartz decreases and micrite increases upwards. Some to Packstone base fine post depositional cracking (possibly due to dewatering after grading coring). Interval represents a gradational contact between sandy up to packstone to fossiliferous floatstone. Abundant benthic forams. light- grey 102

Appendix Table 1 con't 16

Core Depth Grain Intervals Lithology Color Size Sedimentological Properties, biogenic structures, and biota Ichnogeneric

1020.5 1034.0 Sandy Packstone yellow- Fine to Less than 10 % granule to pebble-sized phosphate and dark Ophiomorpha grey very carbonate grains floating in micrite matrix. Well indurated dominate, fine and sandy (high percent of quartz grains (>50%)). Vertical Conichnus and oblique and horizontal burrows (2 - 3 cm in diameter). Thalassinoides Some burrows are unlined while other are lined with pellets rare (Ophiomorpha) and display a darker color than matrix sediment. Burrow fill is typically passive but some burrows have darker sediment fill (possibly active fill).

103 1034.0 1035.0 Floatstone. black to fine to Intense brecciation of floatstone possibly due to exposure

very light pebble and dissolution with phosphatization occurring at base of grey to interval. Area of dissolution appears to be filled with a yellowish course breccia in a micrite matrix that was injected as a grey mobile unit (Reese and Cunningham, in review).

103

Appendix Table 1 con't 17

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 1035.0 1039.8 Floatstone very mud to Abundant molds and casts and a small percent of matrix (15-20%). light granule Bivalves become more abundant and larger (2-5 cm) with some grey to shells bivalve molds infilled with micritic sediment that contains granule-sized phosphate grains and lithoclasts (possibly from above). Good moldic porosity. Irregular surface (possibly phosphatized?) at 1039.8 feet. Molds and casts of brachiopods, gastropods (high-spired (turritela?) common), bivalves and

rhodoliths (encrusting red algae). 104 1039.8 1046.4 Floatstone very mud to Abundant molds and few casts and increased matrix percent (50 - light very 60 %). Irregular surface at 1039.8 feet overlain by yellow grey grey fine to mud that has coarse lithoclasts and borings (?). Crystallization shells inside some shells. Fossil percent increases upward. Well- developed, interconnected moldic porosity. Abundant molds of brachiopods and gastropods (high-spired (turritela?)

104

Appendix Table 1 con't 18

Core Depth Lithology Color Grain Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals Size 1046.4 1050.0 Sandstone very mud to Finning upwards with moderate bioturbation at the base along with light very burrows that have been backfilled with finer sediment (from grey fine above). Bioturbation decreases upwards. At 1046.4 feet at distinct color change from very light grey to dark grey possibly due to increase degree of cementation or phosphatization. Top one inch of interval contains coarse lithoclasts and bioclasts. Few (1 - 2 %) molds of shell fragments and gastropods (<1 %) 1050.0 1059.8 Sandstone light fine to Coarsening and darkening upwards. Cementation increase towards

105 olive medium top of the interval. Sediment is heavily bioturbated with granule-

grey- sand size bioclasts (20%), shell fragments and medium sand-sized

dark phosphate gains. Burrows grade from indistinct at the base to olive sharply defined at the top. Biota includes flat, disk-shaped forams grey

105

Appendix Table 1 con't 19

Core Depth Lithology Color Grain Size Sedimentological Properties, biogenic structures, and biota Ichnogeneric Intervals 1063.9 1064.3 Sandstone yellow- fine sand Gradational coarsening-upwards trend with accumulation of grey coarsening breccia at top of interval. Grains include medium to coarse upwards carbonate lithoclasts and quartz grains with very fine phosphate grains in matrix (10 - 20 %). 1064.3 1066.1 Sandstone yellow- fine sand Fine-grained, vuggy sandstone with angular to sub-angular grey coarsening phosphate and limestone lithoclasts (<1 cm). Gradational upwards coarsening-upwards trend with accumulation of breccia at top of interval. Grains include medium to coarse carbonate

106 and quartz grains with very fine phosphate grains in matrix

(10 - 20 %).

1066.1 1068.0 Wackestone Pale mud with Paleokarst surface (surface of dissolution) at 1066.05 ft. grey to coarse through 1068.25 feet. Possible solution-affected fracture or white lithoclats interstitial pore space produced from microscale dissolution; solution piping? Overlying beds do not display any solution features or evidence of collapse into underlying paleokarst surface suggesting pre-burial solution occurred. Dominate grain type is carbonate pellets; semi-vertical vugs possibly following burrows. Biota includes disk-shaped benthic forams.

106

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