Paleogene-Early Neogene Palynomorphs from the Eastern Equatorial Atlantic and Southeastern Florida, USA: Biostratigraphy and Paleoenvironmental Implications

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Paleogene-Early Neogene palynomorphs from the Eastern Equatorial Atlantic and Southeastern Florida, USA: Biostratigraphy and paleoenvironmental implications

Walaa K. Awad

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Recommended Citation Awad, Walaa K., "Paleogene-Early Neogene palynomorphs from the Eastern Equatorial Atlantic and Southeastern Florida, USA: Biostratigraphy and paleoenvironmental implications" (2018). Doctoral Dissertations. 2665. https://scholarsmine.mst.edu/doctoral_dissertations/2665

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PALEOGENE-EARLY NEOGENE PALYNOMORPHS FROM THE EASTERN

EQUATORIAL ATLANTIC AND SOUTHEASTERN FLORIDA, USA:

BIOSTRATIGRAPHY AND PALEOENVIRONMENTAL IMPLICATIONS

WALAA KAMALELDEEN AWAD

A DISSERTATION

Presented to the Faculty of the Graduate School of the

MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY

In Partial Fulfillment of the Requirements for the Degree

DOCTOR OF PHILOSOPHY

GEOLOGY and GEOPHYSICS

2018

Approved by

Francisca Oboh-Ikuenobe, Advisor John Hogan David Wronkiewicz Wan Yang Lucy Edwards

Walaa Kamaleldeen Awad

iii

To my daughters, Hala and Sara

PUBLICATION DISSERTATION OPTION

This dissertation consists of the following five articles which have been submitted for publication, or will be submitted for publication as follows:

Paper I, pages 3-71 have been accepted by JOURNAL OF AFRICAN EARTH

SCIENCES.

Paper II, pages 72-130 have been accepted by the journal

PALAEOGEOGRAPHY, PALAEOCLIMATOLOGY, PALAEOECOLOGY.

Paper III, pages 131-181 have been accepted by JOURNAL OF AFRICAN

EARTH SCIENCES.

Paper IV, pages 182-224 have been submitted to the journal MARINE

MICROPALEONTOLOGY.

Paper V, pages 225-266 are intended for submission to the journal

MICROPALEONTOLOGY.

ABSTRACT

The transition from greenhouse conditions (Paleocene-Eocene Thermal Maximum,

PETM) to icehouse conditions (Early Oligocene) is not well documented in tropical- subtropical regions. One hundred and five samples from Ocean Drilling Program (ODP)

Site 959 (Hole 959A and Hole 959D) in the Côte d’Ivoire-Ghana Transform Margin, Alo-

1 Well in the northern Niger Delta (Anambra) Basin, Nigeria, and W-17001 in southeastern

Florida were studied for their palynological contents. Dinoflagellate cysts were mainly utilized for age refinement and to detect subtle changes in paleoenvironment and paleoclimate during the Paleocene-Early Eocene (ODP Hole 959D and Alo-1 Well) and

Late Eocene-Early Miocene (ODP Hole 959A and W-17001). Palynofacies analysis and lithologic descriptions supplemented palynomorph data for paleoenvironmental reconstructions in ODP Hole 959A and W-17001. In ODP Hole 959D, five biozones were erected, a Late Paleocene hiatus event was identified, four new dinoflagellate cyst species were formally named, and an outer neritic paleoenvironment was inferred. The paleoenvironment was shallower (inner neritic) in the Alo-1 Well which yielded two new species and had four biozones. Five biozones were established for the Late Eocene-Early

Miocene interval in ODP Hole 959A, proposed the Late Eocene as a new age assignment for lithologic subunit IIB, noted a hiatus event upsection, and observed new biostratigraphic ranges for two dinoflagellate cyst species. A deep paleoenvironment with relatively cold-water masses during the Early Oligocene and hyperstratified conditions was proposed. Two hiatus events and fluctuations between restricted marine and open marine paleoenvironments were inferred in the W-17001.

ACKNOWLEDGEMENTS

First, I would like to thank God for all the blessings. I thank my advisor, Dr.

Francisca Oboh-Ikuenobe, for her support during the last four and half years. There are not enough words to express my deep gratitude to her because this work would not have been achieved without her continuous encouragement and great help. Thank you for teaching me to be strong and self-dependent, for your caring and kindness made this time easier for me. I also extend my appreciation to my committee members for sharing their ideas and suggestions which had a great impact on this work. I acknowledge Drs. Jonathan Obrist-

Farner, Mohamed Zobaa, Onema Adojoh, and Yunis Valdon for their useful discussions.

Special thanks to all my friends: Olufeyisayo Ilesanmi, Damián Cárdenas, Marissa

Spencer, Joel Edegbai, Bin Sun, Xin Zhan, Dongyu Zhang, Dr. Zhixin Li and Dr. Angelica

Alvarez. I extend my appreciation to Sharon Lauck for being so nice and helpful to me. I would like to express my deep gratitude to my mother for taking care of my daughters and helping me to stay focused and productive during my study. I also thank my father, sister, brother, my best friend Sara and mother-in-law for their prayers and support. Special thanks to my brother-in-law, Sherif, for standing by me and caring about my study and future career. My daughters, Hala and Sara, thank you for being patient and tolerant throughout my study; I did all of this for you to be proud of me. I thank my husband for being patient and supportive. Your continuous encouragement helped me tremendously. I acknowledge the Missouri S&T Department of Geosciences and Geological and Petroleum Engineering for the Alfred Spreng Research Award and for supporting me as a teaching assistant.

Finally, I thank all my students for their wonderful support and encouragement.

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TABLE OF CONTENTS

Page PUBLICATION DISSERTATION OPTION ...... iv

ABSTRACT ...... v

ACKNOWLEDGEMENTS ...... vi

LIST OF ILLUSTRATIONS ...... xiv

LIST OF TABLES ...... xvii

LIST OF PLATES ...... xix

SECTION

1. INTRODUCTION ...... 1

PAPER

I. EARLY PALEOGENE DINOFLAGELLATE CYSTS FROM ODP HOLE 959D, CÔTE D'IVOIRE-GHANA TRANSFORM MARGIN, WEST AFRICA: NEW SPECIES, BIOSTRATIGRAPHY AND PALEOENVIRONMENTAL IMPLICATIONS ...... 3

ABSTRACT ...... 3

1. INTRODUCTION ...... 4

2. GEOLOGIC SETTING ...... 7

2.1. TECTONICS...... 7

2.2. LITHOSTRATIGRAPHY ...... 8

3. MATERIALS AND METHODS ...... 9

4. PREVIOUS BIOSTRATIGRAPHIC STUDIES ...... 12

5. RESULTS AND DISCUSSIONS ...... 14

viii

5.1. STRATIGRAPHIC DISTRIBUTION OF DINOFLAGELLATE CYSTS ...... 14

5.2. DINOFLAGELLATE CYST ZONATION ...... 17

5.2.1. Zone 1 ...... 17

5.2.2. Zone 2 ...... 18

5.2.3. Zone 3 ...... 19

5.2.4. Zone 4 ...... 20

5.2.5. Zone 5 ...... 21

5.3. PALEOENVIRONMENTAL RECONSTRUCTION ...... 22

5.3.1. Early Paleocene (Danian, 867.60-860.70 mbsf) ...... 22

5.3.2. Late Paleocene (Selandian, 851.68-828.72 mbsf) ...... 24

5.3.3. Late Paleocene (Thanetian, 822.14-799.88 mbsf) ...... 26

5.3.4. Earliest Eocene (Ypresian, 793.35-776.32 mbsf) ...... 28

6. SYSTEMATIC PALEONTOLOGY ...... 29

7. CONCLUSIONS...... 46

ACKNOWLEDGEMENTS ...... 47

APPENDICES

A. QUANTITATIVE DINOFLAGELLATE CYST DATA FOR ODP HOLE 959D ...... 48

B. LIST OF DINOFLAGELLATE CYST TAXA ...... 53

REFERENCES ...... 60

II. DINOFLAGELLATE CYST ASSEMBLAGES, BIOSTRATIGRAPHY AND PALEOENVIRONMENT OF A PALEOCENE-EARLY EOCENE SEDIMENTARY SUCCESSION IN THE NORTHERN NIGER DELTA BASIN: COMPARISON WITH LOW, MID AND HIGH LATITUDE REGIONS ...... 72

ABSTRACT ...... 72

1. INTRODUCTION ...... 73

2. GEOLOGIC SETTING ...... 75

2.1. TECTONICS...... 76

2.2. STRATIGRAPHY AND SEDIMENTOLOGY ...... 78

3. PREVIOUS BIOSTRATIGRAPHIC STUDIES ...... 80

4. MATERIALS AND METHODS ...... 82

5. RESULTS AND DISCUSSION ...... 85

5.1. STRATIGRAPHIC DISTRIBUTION OF DINOFLAGELLATE CYSTS ...... 85

5.2. DINOFLAGELLATE CYST ZONATIONS ...... 92

5.2.1. Zone E ...... 92

5.2.2. Zone F ...... 93

5.2.3. Zone G ...... 96

5.2.4. Zone H ...... 98

5.3. QUANTITATIVE CHANGES IN THE DINOFLAGELLATE CYST DISTRIBUTION ...... 99

5.3.1. Late Paleocene (Late Selandian, 768.1-493.7 m) ...... 99

5.3.2. Late Paleocene (Thanetian, 438.9-219.4 m) ...... 100

5.3.3. Early Eocene (Ypresian, 201-54.9 m) ...... 102

5.4. INFERRED LITHOSTRATIGRAPHY OF ALO-1 WELL ...... 103

5.5. COMPARISON WITH OTHER LATITUDINAL DINOFLAGELLATE CYST STUDIES ...... 103

6. CONCLUSIONS...... 107

ACKNOWLEDGMENTS ...... 109

APPENDICES

A. QUANTITATIVE DINOFLAGELLATE CYST DATA FOR ALO-1 WELL ...... 110

B. LIST OF DINOFLAGELLATE CYST TAXA ...... 115

C. SYSTEMATIC PALEONTOLOGY ...... 119

REFERENCES ...... 123

III. LATE PALEOGENE-EARLY NEOGENE DINOFLAGELLATE CYST BIOSTRATIGRAPHY OF THE EASTERN EQUATORIAL ATLANTIC ...... 131

ABSTRACT ...... 131

1. INTRODUCTION ...... 132

2. GEOLOGIC SETTING ...... 134

2.1. TECTONICS...... 134

2.2. LITHOSTRATIGRAPHY ...... 135

3. MATERIALS AND METHODS ...... 136

4. PREVIOUS BIOSTRATIGRAPHIC STUDIES ...... 137

5. DINOFLAGELLATE CYST ZONATIONS ...... 142

5.1. ZONE 1 ...... 143

5.1.1. Subzone 1a ...... 143

5.1.2. Subzone 1b ...... 144

5.2. ZONE 2 ...... 147

5.3. ZONE 3 ...... 150

5.4. ZONE 4 ...... 153

5.5. ZONE 5 ...... 155

6. CONCLUSIONS...... 162

ACKNOWLEDGMENTS ...... 163

APPENDICES

A. QUANTITATIVE DINOFLAGELLATE CYST DATA FOR HOLE 959A ...... 164

B. LIST OF DINOFLAGELLATE CYST TAXA ...... 170

REFERENCES ...... 175

IV. PALEOGENE-EARLY NEOGENE PALEOENVIRONMENT AND PALEOCLIMATE RECONSTRUCTION BASED ON PALYNOLOGICAL ANALYSIS OF ODP HOLE 959A, WEST AFRICA ...... 182

ABSTRACT ...... 182

1. INTRODUCTION ...... 183

2. GEOLOGIC SETTING ...... 186

2.1. TECTONICS...... 186

2.2. LITHOSTRATIGRAPHY ...... 187

3. MATERIALS AND METHODS ...... 189

4. RESULTS AND DISCUSSION ...... 190

4.1. INTERVAL 1 (PRIABONIAN-EARLY RUPELIAN, 466.45- 433.33 MBSF)...... 191

4.2. INTERVAL 2 (MIDDLE RUPELIAN-LATE CHATTIAN, 421.32-343.58 MBSF) ...... 199

4.3. INTERVAL 3 (LATE CHATTIAN-LATE AQUITANIAN, 317.94-262.69 MBSF) ...... 204

4.4. INTERVAL 4 (LATE AQUITANIAN- MIDDLE BURDIGALIAN, 244.61- 209.1 MBSF) ...... 206

4.5. INTERVAL 5 (BURDIGALIAN, 200.5-193.25 MBSF) ...... 209

5. CONCLUSIONS...... 215

ACKNOWLEDGMENTS ...... 216

xii

REFERENCES ...... 216

V. LATE EOCENE-EARLY MIOCENE PALYNOMORPHS FROM THE OCALA LIMESTONE, SUWANNEE LIMESTONE AND ARCADIA FORMATION IN W-17001, SOUTHEASTERN FLORIDA, USA: PRELIMINARY BIOSTRATIGRAPHY AND PALEOENVIRONMENTAL RECONSTRUCTION ...... 225

ABSTRACT ...... 225

1. INTRODUCTION ...... 226

2. GEOLOGIC SETTING ...... 228

2.1. TECTONICS...... 228

2.2. LITHOSTRATIGRAPHY ...... 229

3. MATERIALS AND METHODS ...... 231

4. RESULTS AND DISCUSSION ...... 239

4.1. DINOFLAGELLATE CYSTS BIOSTRATIGRAPHY ...... 239

4.1.1. Samples S24-S20 (Priabonian-Earliest Early Rupelian 219.15-191.11 m) ...... 240

4.1.2. Samples S19-S14 (Rupelian-Early Chattian?, 188.06- 178.00 m) ...... 241

4.1.3. Samples S13-S6 (Aquitanian, 174.04-155.80 m) ...... 245

4.2. PALEOENVIRONMENTAL RECONSTRUCTION ...... 246

4.2.1. Palynofacies Interval 1, S24-S21 (Lower Part of Dinoflagellate Cyst Interval A) ...... 248

4.2.2. Palynofacies Interval 2, S20-S6 (Upper Part of Dinoflagellate Cyst Interval A, Interval B and Interval C) ...... 249

4.2.2.1. Dinoflagellate cyst interval A (S19-S16) ...... 249

4.2.2.2. Dinoflagellate cyst interval B (S15-S14) ...... 251

4.2.2.3. Dinoflagellate cyst interval C (S13-S8) ...... 252

xiii

4.2.3. Palynofacies Interval 3, S5-S1 ...... 253

5. CONCLUSIONS...... 259

ACKNOWLEDGMENTS ...... 260

REFERENCES ...... 260

SECTION

2. CONCLUSIONS...... 267

VITA ...... 269

xiv

LIST OF ILLUSTRATIONS

PAPER I Page

Fig. 1. Location map of ODP Site 959 showing the main morpho-structural features of the Côte d’Ivoire-Ghana Transform Margin in West Africa ...... 6

Fig. 2. Schematic stratigraphic column...... 11

Fig. 3. Biostratigraphic ranges of selected dinoflagellate cysts in Hole 959D ...... 16

Fig. 4. Proposed Dinoflagellate cyst zones using the last occurrence (LO) or first occurrence (FO) of dinoflagellate cyst taxa in the Early Paleogene interval ...... 23

Fig. 5. Quantitative distribution of selected dinoflagellate cysts in samples with >100 recovered specimens in the Paleocene-Early Eocene interval ...... 27

PAPER II

Fig. 1. Map of Southern Nigeria showing the location of Alo-1 Well in the Anambra Basin and megatectonic frame of southern Nigeria sedimentary basin ...... 77

Fig. 2. Summary of stratigraphic data of the Paleogene succession in southeastern Nigeria...... 79

Fig. 3. Lithology, inferred stratigraphy and sample horizons in the interval studied ...... 85

Fig. 4. Photomicrographs no 1 of dinoflagellate cysts...... 87

Fig. 5. Photomicrographs no 2 of dinoflagellate cysts...... 88

Fig. 6. Photomicrographs no 3 of dinoflagellate cysts...... 89

Fig. 7. Photomicrographs no 4 of dinoflagellate cysts...... 90

Fig. 8. Biostratigraphic ranges of selected dinoflagellate cysts ...... 91

Fig. 9. Proposed dinoflagellate cyst zones using the last occurrences (LOs) or last abundance events of one or more taxa in the Paleocene to Early Eocene interval of Alo-1 Well, and comparison with other zonations ...... 95

Fig. 10. Quantitative distribution (in percent) of selected dinoflagellate cyst assemblages in the Paleocene to Early Eocene interval ...... 105

PAPER III

Fig. 1. Map showing the location of ODP Site 959 (indicated by red circle) in the Côte d’Ivoire-Ghana (CIG) Transform Margin in the eastern Equatorial Atlantic, West Africa ...... 135

Fig. 2. The lithostratigraphy of ODP Site 959 (units I to V) (modified from Shipboard Scientific Party,1996) and sample horizons in the studied interval ...... 140

Fig. 3. Range chart of the selected dinoflagellate cysts ...... 146

Fig. 4. Comparison between the proposed dinoflagellate cyst (sub)zones in the Late Eocene to Early Miocene of ODP Hole 959A with other zonations ...... 148

Fig. 5. Photomicrographs no 1 of dinoflagellate cysts ...... 157

Fig. 6. Photomicrographs no 2 of dinoflagellate cysts ...... 158

Fig. 7. Photomicrographs no 3 of dinoflagellate cysts ...... 159

Fig. 8. Photomicrographs no 4 of dinoflagellate cysts ...... 160

Fig. 9. Photomicrographs no 5 of dinoflagellate cysts ...... 161

PAPER IV

Fig. 1. Map showing the location of ODO Hole 959A in the Côte d’Ivoire-Ghana Transform Margin in the eastern Equatorial Atlantic, West Africa...... 185

Fig. 2. Schematic stratigraphic column for ODP site 959 ...... 188

Fig. 3. Summary of the lithologic and biostratigraphic data for ODP Hole 959A ...... 192

Fig. 4. Relative abundances (in percent) of selected dinoflagellate cysts and terrestrial palynomorphs (pollen and spores) in the Late Eocene-Early Miocene interval ...... 202

Fig. 5. Relative abundances (in percent) of the particulate organic matter components in the studied section ...... 208

Fig. 6. Photomicrographs no 1 of dinoflagellate cysts ...... 212

Fig. 7. Photomicrographs no 2 of dinoflagellate cysts ...... 213

Fig. 8. Photomicrographs no 3 of dinoflagellate cysts ...... 214

xvi

PAPER V

Fig. 1. Map showing the location of W-17001 in the southeastern part of Florida, USA...... 227

Fig. 2. The lithostratigraphy of W-17001and sample horizons in the studied interval ...... 230

Fig. 3. Pictures of some samples of the studied interval ...... 236

Fig. 4. Range chart of the selected dinoflagellate cysts in the Late Eocene-Early Miocene interval of W-17001 ...... 239

Fig. 5. Relative abundances (in percent) of selected dinoflagellate cysts in the Late Eocene-Early Miocene interval...... 242

Fig. 6. Relative abundances (in percent) of the particulate organic matter components in the studied section ...... 243

xvii

LIST OF TABLES

PAPER I Page

Table 1. List of samples, core-section, interval, Missouri University of Science and Technology repository no. and sample depths for ODP Hole 969D; mbsf = meter below sea floor ...... 12

Table 2. Morphological taxa and groups representing 80-90% of the dinoflagellate cyst assemblage in ODP Hole 959D ...... 24

PAPER II

Table 1. List of Alo-1 Well samples and their corresponding Missouri University of Science and Technology repository numbers and depths ...... 84

Table 2. Comparison between Alo-1 dinoflagellate cysts and taxa in high and mid latitudes ...... 106

PAPER III

Table 1. Summary of the lithostratigraphy of ODP site 959 ...... 139

PAPER IV

Table 1. List of samples, Missouri University of Science and Technology Repository no. (showing slide no) and sample depths for ODP Hole 959D; mbsf = meter below sea floor ...... 193

Table 2. Raw count data for dinoflagellate cyst groups/species and sporomorphs (pollen and spores) ...... 194

Table 3. Point count data for particulate organic matter components ...... 196

Table 4. Dinoflagellate cyst groups and their possible ecological interpretation ...... 201

xviii

PAPER V

Table 1. List of samples and sample depths for Florida W-17001 ...... 233

Table 2. Detailed lithologic description of the processed samples ...... 234

Table 3. Raw count data for dinoflagellate cyst species ...... 237

Table 4. Point count data for particulate organic matter components ...... 238

xix

LIST OF PLATES

PAPER I Page

Plate I. Photomicrographs no 1 of dinoflagellate cysts...... 39

Plate II. Photomicrographs no 2 of dinoflagellate cysts...... 40

Plate III. Photomicrographs no 3 of dinoflagellate cysts ...... 41

Plate IV. Photomicrographs no 4 of dinoflagellate cysts ...... 42

Plate V. Photomicrographs no 5 of dinoflagellate cysts ...... 43

Plate VI. Photomicrographs no 6 of dinoflagellate cysts ...... 44

Plate VII. Photomicrographs no 7 of dinoflagellate cysts ...... 45

PAPER V

Plate I. Photomicrographs no 1 of dinoflagellate cysts...... 254

Plate II. Photomicrographs no 2 of dinoflagellate cysts...... 255

Plate III. Photomicrographs no 3 of dinoflagellate cysts ...... 256

Plate IV. Photomicrographs no 4 of dinoflagellate cysts ...... 257

Plate V. Photomicrographs no 5 of dinoflagellate cysts ...... 258

1. INTRODUCTION

Palynology is a branch of paleontology dealing with organic-walled microfossils

(palynomorphs) such as pollen, spores, dinoflagellate cysts, acritarchs and foraminiferal wall linings that are generally 5-500 μm in size. The Paleogene to Early Neogene is considered a very dynamic time in Earth’s history because of climate change. Multiple proxies have been used to record these changes and palynomorphs have been proved to be one the best tools for tracking the changes. Pollen and spores are terrestrial palynomorphs that have been utilized to infer the changes in land vegetation. Dinoflagellate cysts and acritarchs, on the other hand, are mainly marine palynomorphs, and have been used for age dating as well as interpreting paleoclimate, paleoenvironment, paleoecology, and paleoproductivity.

This dissertation documents comprehensive palynological analyses of two geologic time intervals at four tropical-subtropical localities, three of them located in West Africa and one in Florida. These localities are as follow: (1) Ocean Drilling Program (ODP) Site

959 (Hole 959D) in the Côte d’Ivoire-Ghana Transform Margin; (2) Alo-1 Well in the northern Niger Delta (Anambra) Basin, Nigeria; (3) ODP Hole 959A; and (4) W-17001 in southeastern Florida. Few studies are available for these locations due mainly to poorly preserved environmental settings and confidentiality associated with acquiring data from the petroleum companies prospecting in the tropics.

The aim of the research is to use palynomorphs in low and mid latitude regions to understand the transition from greenhouse (Paleocene-Eocene Thermal Maximum, PETM) to icehouse (Early Oligocene) conditions. We utilize palynomorphs (mainly dinoflagellate 2 cysts) for age refinement and to detect subtle changes in paleoenvironment and paleoclimate during the Paleocene-Early Eocene (ODP Hole 959D and Alo-1 Well) and the Late Eocene-Early Miocene (ODP Hole 959A and W-17001). The first and last occurrence events of dinoflagellate cysts are utilized to erect Paleogene and Early Neogene palynological biozonations, in addition to naming six new Paleogene species. We refine tropical/subtropical biostratigraphy for the Paleocene-Eocene and Oligocene-Miocene by reconstructing low-mid latitude inner neritic zonations vs. outer neritic-oceanic zonations and comparing them with zonations from other latitudinal regions. Palynofacies analysis and lithologic descriptions supplement palynomorph data for paleoenvironmental reconstructions in ODP Hole 959A and W-17001.

The following studies have been published as peer-reviewed journal articles and are compiled in this dissertation: (1) new species, biostratigraphy and paleoenvironment of

ODP Hole 959D; (2) biostratigraphy and paleoenvironment of Alo-1 Well; and (3) biostratigraphy of ODP Hole 959A. Also included in this dissertation are the paper on the paleoenvironment and paleoclimatic reconstruction of ODP Hole 959A submitted to a journal and the paper on the biostratigraphy and paleoenvironmental reconstruction of W-

17001 being prepared for journal submission.

PAPER

I. EARLY PALEOGENE DINOFLAGELLATE CYSTS FROM ODP HOLE 959D, CÔTE D'IVOIRE-GHANA TRANSFORM MARGIN, WEST AFRICA: NEW SPECIES, BIOSTRATIGRAPHY AND PALEOENVIRONMENTAL IMPLICATIONS

Walaa K. Awad, Francisca E. Oboh-Ikuenobe

Geology and Geophysics Program, Department of Geosciences and Geological and

Petroleum Engineering, Missouri University of Science and Technology, 129 McNutt

Hall, Rolla, MO 65409-0410, USA

ABSTRACT

A nearly continuous sedimentary record from Ocean Drilling Program (ODP) Site

959 (Hole 959D) in the Côte d’Ivoire-Ghana Transform Margin provides the opportunity to study Lower Paleogene palynology in this equatorial region. This paper presents data for 117 dinoflagellate cyst taxa recorded in 18 samples covering a 91-m interval from

867.60 mbsf to 776.32 mbsf. Preservation of dinoflagellate cysts varied from poor to excellent, and recovery was almost superabundant. Based on last or first occurrence of dinoflagellate cyst events, five zones (zone 1 to zone 5) were identified. The concentration of several dinoflagellate cyst events in the Thanetian interval suggests the presence of hiatuses or condensed horizons as inferred in previous studies of nearby localities. Frequent to common abundance of Apectodinium in the upper Thanetian sediments apparently records the global episodes of intense climatic warming that characterized the latest

Paleocene to earliest Eocene time. An assemblage dominated by species of

Operculodinium, Spiniferites, and Tectatodinium confirms the outer neritic to oceanic

4 depositional setting of the drill hole as previously inferred from lithologic characteristics.

Finally, four new dinoflagellate cyst taxa, Adnatosphaeridium ivoriense, Diphyes digitum,

Eocladopyxis furculum and Tectatodinium nigeriaense that were observed only in the

Paleocene interval, have been formally identified and described in detail.

Key words: dinoflagellate cysts; biostratigraphy and paleoenvironment; taxonomy; ODP

Hole 959D, Côte d’Ivoire-Ghana Transform Margin; West Africa; Early Paleocene to

Early Eocene.

1. INTRODUCTION

The Paleocene-Eocene epochs represent a global transition in the climate system and carbon cycle perturbations. An abrupt rise in the temperature (global warming hyperthermals, 6-8 ºC) recorded at the Paleocene-Eocene Thermal Maximum (PETM)

(Zachos et al., 2001; Westerhold et al., 2011; Stassen et al., 2012) is considered to be one of the most dramatic events in the Cenozoic. This resulted in a great turnover of both marine and terrestrial living organisms (Sluijs et al., 2007; Speijer et al., 2012). Most prominent was the extinction of deep-sea benthic foraminifera (Thomas, 1998), expansion and diversity in planktonic foraminifera (Kelly et al., 1998; Speijer et al., 2012), turnover in calcareous nannoplankton (Raffi et al., 2009), an acme event of the organic-walled dinoflagellate genus Apectodinium (Crouch et al., 2003, 2014; Slimani et al., 2016), dramatic evolution of mammals (Gingerich, 2006; Sluijs et al., 2007), and distinctive floral changes (Jaramillo et al., 2010).

Dinoflagellates are unicellar phytoplankton that have two flagella, which are responsible for red tides and shellfish poisoning (Fensome et al., 1993, 1996; Bujak and

Brinkhuis, 1998; Crouch et al., 2001). They are useful marine paleoenvironmental indicators and their distribution is controlled by three main factors, namely sea surface temperature (SST), availability of nutrients, and salinity trend (Dale and Fjellså, 1994; Dale,

1996; Dale et al., 2002). These factors can be used to establish many ecological zones for dinoflagellates, separate the coastal and oceanic water, and distinguish between brackish and hypersaline specimens (Dale and Fjellså, 1994).

Organic-walled dinoflagellate cysts have been used intensively in the mid-high latitude regions for Early Paleogene biostratigraphy and paleoenvironmental interpretations (Heilmann-Clausen, 1985; Wilson, 1987, 1988; Bujak and Mudge, 1994;

Mudge and Bujak, 1996; Powell et al., 1996; Sluijs and Brinkhuis, 2009; Quattrocchio,

2009; Willumsen and Vajda, 2010; Iakovleva and Heilmann-Clausen, 2010; Iakovleva,

2011; Nøhr-Hansen et al., 2011; Willumsen, 2003, 2006, 2011, 2012; Bijl et al., 2013;

Crouch et al., 2014; Slimani et al., 2016). This is in contrast to the equatorial regions where they have been used for few environmental or zonal schemes for the Paleocene-Eocene interval (Bujak and Brinkhuis, 1998). The few detailed studies of dinoflagellate cyst gave an overview about tropical dinoflagellate composition in some areas, such as Nigeria (Jan du Chêne and Adediran, 1985; Willumsen et al., 2004; Antolinez, 2006; Antolinez and

Oboh-Ikuenobe, 2007), Senegal (Jan du Chêne, 1988), and Côte d’Ivoire-Ghana (Oboh-

Ikuenobe et al., 1997, 1998; Masure et al., 1998).

Willumsen et al. (2004) provided information about the paleoenvironmental interpretation of the Paleocene-Eocene interval in West Africa. The difference in the dinoflagellate cyst assemblages across this interval suggested changes in the sea surface temperature, nutrients and degree of runoff.

The existence of a nearly continuous Lower Paleogene sedimentary record in Ocean

Drilling Program (ODP) Site 959 (Hole 959D) in the Côte d’Ivoire-Ghana Transform

Margin (Fig. 1) provided the opportunity to accomplish the following objectives: 1) taxonomical identifications of dinoflagellate cysts and formal designations of new four species; 2) establish Early Paleogene zonation by examining the first and last occurrences of dinoflagellate cysts and correlate this scheme to calcareous microfossil data (Shafik et al., 1998); and 3) paleoenvironmental reconstruction of the Early Paleocene to Early

Eocene interval in West Africa.

Fig. 1. Location map of ODP Site 959 showing the main morpho-structural features of the Côte d’Ivoire-Ghana Transform Margin in West Africa (modified from Pickett and Allerton, 1998). Inset shows the location of ODP Leg 159 in the eastern Equatorial Atlantic.

2. GEOLOGIC SETTING

Site 959 is situated on the Côte d’Ivoire-Ghana (CIG) Transform Margin in 2100 m water depth at latitude 3º37.70´N, longitude 2º44.10´W. Four holes (959A, 959B, 959C,

959D) were drilled, with a maximum penetration in Hole 959D at 1158.9 meter below sea floor (mbsf) (Fig. 1). The main reason for drilling in the Côte d’Ivoire-Ghana Transform

Margin was to better understand the lithological composition, sedimentary processes, age, tectonics, and paleoceanographic evolution of the eastern Equatorial Atlantic (Mascle et al., 1996; Hisada et al., 1998).

2.1. TECTONICS

The Côte d’Ivoire-Ghana continental margin consists of northern and southern segments. The north segment includes most of the eastern Ivorian continental slope and southwestern Ghanaian upper slope, which is known as Deep Ivorian Basin. The northeast/southwest trending Côte d’Ivoire-Ghana Margin Ridge (CIGMR) represents the south segment (Fig. 1).

Four tectonic evolution stages (A-D) have been proposed for the Côte d’Ivoire-

Ghana Transform margin (Basile et al., 1992, 1993, 1998; Shipboard Scientific Party,

1996; Benkheil et al., 1998). During Stage A (Early Rifting, Early Cretaceous), Africa and

South America were connected, but the separation of the two continents happened possibly during the Neocomian by the opening of the equatorial Atlantic Ocean. As a result, the

Deep Ivorian Basin was created by an east-west to east-northeast—west-southwest oriented extension. With increasing stretching of the crust, the basin became deeper and

8 the relative shear motion between the African and South American plates affected the southern border. Rifting ended during Stage B (Intracontinental Transform, Aptian-Albian) when the oceanic crust was formed, and post-rift unconformity was one of the evidences that the two continents broke up during this time. Drift stage between the African and South

American plates was formed along the southern border of the Deep Ivorian Basin.

Stage C (Continent/Ocean Transform, latest Albian-Cenomanian) resulted in the formation of the Gulf of Guinea oceanic crust and continental transform margin as a result of the final continental parting between West Africa and northeastern Brazil. The contact between the hot oceanic lithosphere and cold continental crust resulted in the uplift of the

CIGMR, the top of which was subsequently eroded during the Cenomanian times by flower structures and shearing. Stage D (Passive margin evolution) was marked by the cessation of active tectonism and a distinct erosional surface between the uppermost Albian and lower Turonian at all Leg 159 sites. Major Cenozoic lowstand caused strong submarine erosion represented by canyon and wide submarine valleys.

2.2. LITHOSTRATIGRAPHY

Shipboard Scientific Party (1996) divided the Hole 959D sediment into five lithological units (I to V downsection, Fig. 2). Unit I (Holocene to Early Miocene, 208 m) consists of nannofossil ooze and chalk, foraminifera ooze and chalk, and nannofossil ooze or chalk with clay. It is subdivided into two lithologic subunits IA and IB because of alternation from darker to lighter color downunit. Unit II (Early Miocene to Late Paleocene,

599.3 m) has three subunits (IIA-IIC) composed of alternating siliceous and calcareous sediments. Subunit IIA comprises interbedded nannofossil chalk, diatomite, and clay;

9 subunit IIB has a black chert layer; while micrite chalk and porcellanite were designated lithologic subunit IIC. Unit lithology II reflects a high productivity time period with high nutrient supply that was probably deposited in the outer shelf (Shipboard Scientific Party,

1996).

Unit III (Late Paleocene to early Coniacian, 231 m) has black claystone and claystone with nannofossils. Many authigenic minerals such as barite, pyrite and glauconite identified in this unit indicate a deep basinal setting. Unit IV (early Coniacian to early

Turonian and unknown age, 38.4 m) comprises sandy limestone, sandy dolomite, calcareous sandstone and limestone. The unit is divided into two subunits (IVA, IVB) depending on differences in the lithology and sedimentary characteristics such as bedding.

This unit has more high energy, coarse clastic rocks than the upsection units. Furthermore, the limestone was formed under reef processes in a shallow shelf depositional environment

(Shipboard Scientific Party, 1996; Pickett and Allerton, 1998). Unit V (late Albian, 77.2 m) consists of quartz sandstone and silty claystone deposited in a deep-water lacustrine setting (Shipboard Scientific Party, 1996; Pickett and Allerton, 1998; Strand, 1998; Hisada et al., 1998). The micritic porcellanite in the lower part of subunit IIC and claystone with glauconite and pyrite in the upper part of unit III are the focus of this study.

3. MATERIALS AND METHODS

Eighteen samples were examined for their dinoflagellate cyst contents (Fig. 2;

Table 1). The lower part of the studied Paleogene succession consists of claystone with glauconite and pyrite (unit III), and it is succeeded by micritic porcellanite (subunit IIC;

Fig. 2). The organic fractions of the samples were extracted using standard laboratory techniques of digesting the sediments in hydrochloric and hydrofluoric acids, and centrifuging in heavy liquid (ZnBr2) (Traverse, 2007). Half of the organic residues were oxidized using Schultze solution (KClO3 plus HNO3) and screened through 10 μm sieves.

Half of the oxidized residues were stained with safranin red. Both unoxidized and oxidized palynological residues were mounted on the palynological slides. A minimum of 300 dinoflagellate cysts was counted per sample, except for those samples with poor yields, in order to estimate the relative abundance of each taxon. Additionally, a minimum of 300 sporomorphs (spores and pollen) vs. dinoflagellate cysts were counted in order to record variations in the proportion of terrestrial and marine components related to changes in the depositional site. One hundred and seventeen dinoflagellate cyst taxa were identified in the studied interval from ODP Hole 959D (Appendix A). The samples mostly yielded abundant and well-preserved dinoflagellate cysts, although few samples were not very productive.

Only samples with more than 100 dinoflagellate cyst taxa have been used for quantitative analysis. The quantitative data were converted to percentages and discussed as follows: rare (<1-5%), common (6-10%), frequent (11-20%), abundant (21-40%) and superabundant (>40%). For identification and descriptions of the dinoflagellate cysts, a

Nikon transmitted light microscope with interference contrast was used. All the materials are housed in the palynological repository located in the Paleontology Laboratory at

Missouri University Science and Technology, USA. The plate captions contain details of the illustrated specimens, which include the sample number, and England Finder (EF) reference.

The systematic classification and nomenclature of dinoflagellate cysts follow

Fensome et al. (2008), and the descriptive terminology follows Evitt (1985) and Williams et al. (2000). Shafik et al. (1998) calibrated the calcareous nannoplankton data in ODP

Hole 959D with the geologic timescale of Berggren et al. (1995). This information was used to establish the dinoflagellate cyst bioevents for the Early Paleogene interval in Hole

959D.

Fig. 2. Schematic stratigraphic column. Lithological units (I to V) determined by the Shipboard Scientific Party (1996) and sample horizons in the studied interval (modified from Strand, 1998).

4. PREVIOUS BIOSTRATIGRAPHIC STUDIES

A variety of microfossils were used in the age assignment of the Côte d’Ivoire-

Ghana Transform Margin (Bellier, 1998; Holbourn and Moullade, 1998; Kuhnt et al., 1998;

Masure et al., 1998; Oboh-Ikuenobe et al., 1998; Shafik et al., 1998). Masure et al. (1998) and Oboh-Ikuenobe et al. (1998) studied palynomorphs in the Cretaceous and Paleocene samples from sites 959, 960, 961 and 962. In addition, agglutinated foraminifera and calcareous nannafossil in the Early Paleogene interval in ODP Hole 959D were analyzed by Kuhnt et al. (1998) and Shafik et al. (1998), respectively.

Table 1. List of samples, core-section, interval, Missouri University of Science and Technology repository no. and sample depths for ODP Hole 969D; mbsf = meter below sea floor.

Samples ODP Leg 159, Hole 959D, Repository No. Depth (mbsf) Core-Section, Interval (cm) CIG1 39R-2, 51-56 MST-1914-S1 776.32 CIG2 40R-3, 80-86 MST-1915-S1 787.35 CIG3 41R-1, 32-37 MST-1915-S5 793.35 CIG4 41R-5, 85-91 MST-1915-S9 799.88 CIG5 42R-1, 52-56 MST-1915-S13 803.12 CIG6 42R-3, 70-72 MST-1915-S18 806.30 CIG7 43R-1, 4.5-6.5 MST-1915-S21 812.34 CIG8 43R-2, 100-102.5 MST-1915-S23 814.80 CIG9 43R-4, 50-53 MST-1915-S27 817.30 CIG10 44R-2, 4-6 MST-1915-S30 822.14 CIG11 44R-5, 82.5-85 MST-1915-S33 828.72 CIG12 44R-7, 133-136 MST-1915-S35 830.93 CIG13 45R-1, 0-4 MST-1915-S40 831.64 CIG14 46R-CC, 5-7 MST-1928-S1 844.35 CIG15 47R-1, 78-80 MST-1930-S1 851.68 CIG16 48R-1, 10-13 MST-1931-S1 860.70 CIG17 48R-3, 65-68 MST-1932-S 864.06 CIG18 48R-5, 96-100 MST-1934-S1 867.60

Oboh-Ikuenobe et al. (1998) used pollen, spores and dinoflagellate cysts to place the Maastrichtian-Danian boundary between samples 159-959D-48R-5, 37-41 cm (866.97 mbsf), and 159-959D-49R-4, 99-102 cm (875.69 mbsf). Typical Danian dinoflagellate cysts are present in sample 159-959D-48R-5, 37-41 cm (866.97 mbsf), which records the co-occurrence of Hafniasphaera septata, Fibrocysta bipolaris and Cerodinium diebelii and the absence of important Maastrichtian species (Dinogymnium spp. and Pierceites pentagona).

Masure et al. (1998) also studied the dinoflagellate cysts in the Paleocene interval of ODP Hole 959D. They assigned an Early Paleocene age to the interval below sample

159-959D- 45R-1, 11-16 cm (831.71 mbsf) due to the appearance of some marker species for this time period, such as Damassadinium californicum, Impagidinium celineae and

Kallosphaeridium yorubaense. They used the co-occurrence of Adnatosphaeridium multispinosum and Apectodinium spp. to suggest a late Thanetian age for sample 159-

959D- 44R-6, 60-62 cm (828.70 mbsf).

Kuhnt et al. (1998) analyzed the benthic foraminifera in ODP Hole 959D and noted some important biostratigraphic changes within Core 159-959D-48R (870 to 860 mbsf) indicative of the Cretaceous-Paleogene boundary. The last occurrence of Caudammina gigantean (distinctive late Maastrichtian species) and superabundant occurrence of

Spiroplectammina spectabilis (worldwide Paleogene event) were observed in samples 159-

959D-48R-6, 28-31 cm (~668 mbsf) and 159-959D-48R-4 (~667 mbsf), respectively. They assigned sample 159-959D-44R (~832 mbsf) to a Late Paleocene age

(Selandian/Thanetian) based on the first occurrence of Reticulophragmoides jarvisi.

Shafik et al. (1998) studied the calcareous nannofossils in ODP Hole 959D and proposed bio (sub)zones (CP7/CP9b) through the Late Paleocene-Early Eocene interval.

No (sub)zones were established for the Early Paleocene below sample 159-959D-44R-3,

72-73 cm (825.6 mbsf) because the sediments were barren of calcareous nannofossils (Fig.

3). Zone CP7 to subzone CP8b were assigned to a Late Paleocene (Thanetian) age. The co- occurrence of Rhomboaster bitrifida and Campylosphaera eodela and highest occurrence of Fasciculithus in sample 159-959D-41R-CC (802 mbsf) were used to place subzone

CP8b at the top of the Paleocene. Early Eocene age was proposed for zone CP9 due to the appearance of such distinctive calcareous nannofossils as Tribrachiatus bramlettei, T. contortus and Hornibrookina australis. Finally, Shafik et al. (1998) placed the Paleocene-

Eocene boundary at approximately 797 mbsf, between samples 159-959D-41R-CC and

159-959D-41R-2, 96-97.

5. RESULTS AND DISCUSSIONS

5.1. STRATIGRAPHIC DISTRIBUTION OF DINOFLAGELLATE CYSTS

The stratigraphic ranges of selected dinoflagellate cysts and a summary of the Early

Paleogene biostratigraphy based on calcareous nannofossils are shown in Fig. 3. The presence of Cerodinium diebelii, Damassadinium californicum, Diphyes digitum sp. nov.,

Exochosphaeridium bifidum, Ifecysta lappacea, Magallanesium densispinatum and

Trichodinium hirsutum characterizes the lower portion of the section below sample CIG16

(860.70 mbsf). Palaeocystodinium golzowense has an acme occurrence in sample CIG17

(864.06 mbsf), while Tectatodinium nigeriaense sp. nov. and Spiniferella cornuta are also common to frequent in this part of the section.

Acmes of Areoligera gippingensis, Tectatodinium nigeriaense sp. nov.,

Batiacasphaera spp., and common to frequent occurrence of both Glaphyrocysta spp. and

Impletosphaeridium spp. are observed between 860 and 820 mbsf. Furthermore, several biostratigraphic events are recorded in this interval: the last occurences (LOs) of Ifecysta fusiforma and Ifecysta Pachyderma in sample CIG14 (844.35 mbsf), and the LOs of

Areoligera gippingensis, Glaphyrocysta divaricata and Glaphyrocysta ordinata in sample

CIG11 (828.72 mbsf). Also noted is the spot occurrence of Wilsonidium nigeriaense in sample CIG10 (822.14 mbsf) in calcareous nannoplankton zone CP7. In the same sample, an acme of Impletosphaeridium and frequent occurrence of Apectodinium are observed.

The LO of Tectatodinium nigeriaense sp. nov. is recorded in sample CIG9 (817.30 mbsf), followed by the LOs of Batiacasphaera spp., Hafniasphaera hyalospinosa,

Kallosphaeridium orchiesense, Thalassiphora delicata, and the spot occurrence of

Eocladopyxis furculum sp. nov. in sample CIG7 (812.34 mbsf) located in calcareous nannoplankton CP8a subzone. The LOs of several taxa are observed in CP8b below 800 mbsf: Adnatosphaeridium ivoriense sp. nov., Apectodinium spp., Deflandrea oebisfeldensis, Homotryblium abbreviatum, Impagidinium celineae, Impletosphaeridium spp., Kallosphaeridium yorubaense, Melitasphaeridium pseudorecurvatum,

Palaeocystodinium golzowense and Spiniferella cornuta. The upper portion of the drill hole above 800 mbsf is characterized by high abundance of Adnatosphaeridium multispinosum,

Cordosphaeridium gracile, Homotryblium tenuispinosum, Polysphaeridium spp., and

Muratodinium fimbriatum through calcareous nannoplankton CP9 zone (Plates I-VII).

Fig. 3. Biostratigraphic ranges of selected dinoflagellate cysts in Hole 959D. Shown to the right of the figure are the calcareous nannoplankton zonation of Shafik et al. (1998) and the Dinoflagellate cyst zones proposed in this study.

5.2. DINOFLAGELLATE CYST ZONATION

Based on qualitative and quantitative analyses of dinoflagellate cyst bioevents, five biostratigraphic zones are proposed. The dinoflagellate cyst zones are labeled as zone 1 to zone 5 and they are interval zones. The zones are defined by first or last occurrence of important biostratigraphic dinoflagellate cysts. They are calibrated with calcareous nannoplankton biostratigraphy of ODP Hole 959D in the upper part of the interval (Shafik et al., 1998). Due to the absence of calcareous nannoplankton in the lower part of the section, the age assignments are inferred from some important global bioevents noted in previous studies (e.g. Williams and Bujak, 1985; Brinkhuis et al., 1994; Stover et al., 1996;

Oboh-Ikuenobe at al., 1998, 2012; Williams et al., 2004; Bankole et al., 2007; Mbesse et al. 2012; Crouch et al., 2014; Slimani et al., 2016). A summary diagram (Fig. 4) shows details of zone 1 to zone 5.

5.2.1. Zone 1. Definition. The top of the zone is defined by the LO of Cerodinium diebelii. The base of the zone is not defined in this study.

Other useful bioevents. Palaeocystodinium golzowense and Tectatodinium nigeriaense sp. nov are the main dinoflagellate cysts present in this zone. Damassadinium californicum, Diphyes digitum sp. nov., Exochosphaeridium bifidum, Magallanesium densispinatum, and Trichodinium hirsutum are restricted to this zone

Age range. Early Paleocene (Danian), ODP Hole 959D from sample CIG18 (867.60 mbsf) to sample CIG16 (860.70 mbsf).

Comments. Cerodinium diebelii, Exochosphaeridium bifidum, Ifecysta lappacea

Magallanesium densispinatum, and Palaeocystodinium golzowense have been observed in the Danian rocks in many studies (Jan du Chêne, 1988; Brinkhuis et al., 1994; Masure et

18 al., 1998; Antolinez and Oboh-Ikuenobe, 2007; Oboh-Ikuenobe at al., 1998, 2012; Slimani et al., 2010, 2016). Damassadinium californicum is a significant Danian species (Williams and Bujak, 1985; Brinkhuis and Zachariasse, 1988; Powell, 1992; Masure et al., 1998;

Slimani et al., 2016). Cerodinium diebelii was observed and used for biozonation by Jan du Chêne et al. (1975) and Van Stuijvenberg et al. (1976) in the Danian of Switzerland.

Furthermore, the LOs of Cerodinium diebelii and Trichodinium hirsutum were recorded in the late Danian of equatorial regions (Williams et al., 2004) and New Zealand (Willumsen,

2003, 2006, 2011, 2012; Crouch et al., 2014).

5.2.2. Zone 2. Definition. The base of the zone is defined by the LO of Cerodinium diebelii. The top of the zone is defined by the LO of Areoligera gippingensis.

Other useful bioevents. Acmes of Areoligera gippingensis and Tectatodinium nigeriaense sp. nov. follow the LO of Cerodinium diebelii in the lower portion of the zone.

Two more acmes of Batiacasphaera and Glaphyrocysta spp. are recorded at the top of the zone. Apectodinium spp. is also observed for the first time in the upper part of zone 2.

Age range. Late Paleocene (Selandian-earliest Thanetian), ODP Hole 959D, 31.98 m thick, from sample CIG16 (860.70 mbsf) to sample CIG11 (828.72 mbsf). The top of the zone is closely correlated to the lower boundary of calcareous nannoplankton zone CP7.

Comments. The FO of Apectodinium supports the inferred Selandian-early

Thanetian age in low latitudes regions (Brinkhuis et al., 1994; Bujak and Brinkhuis, 1998;

Egger et al., 2000; Iakovleva et al., 2001; Crouch et al., 2003; Guasti et al., 2005, 2006;

Slimani et al., 2016). The earliest appearance of Apectodinium spp. is known in El Kef

Section in Tunisia at the base of the Selandian and is mainly represented by few numbers

(Brinkhuis et al., 1994, Bujak and Brinkhuis, 1998), while in mid and high latitudes, the

19 first appearance is usually observed in the Thanetian (e.g. Powell et al., 1996; Crouch et al., 2014). In this study, the FO of Apectodinium spp. is close to the Selandian-Thanetian boundary (<5% abundance). The occurrence of Ifecysta spp. through this zone (Ifecysta pachyderma and Ifecysta fusiforma, Fig. 3) supports the age assignment for Late Paleocene, and it has also been recorded in previous studies in West Africa (Jan du Chêne and

Adediran, 1985; Antolinez, 2006; Antolinez and Oboh-Ikuenobe, 2007; Bankole et al.,

2007; Mbesse et al. 2012). The LO of A. gippingensis recorded here is slightly older than that in mid-latitudes of the Northern Hemisphere (middle Thanetian, 57 Ma, Powell et al.,

1996; Williams et al., 2004). Possible reasons for this disparity may include: paleoenvironmental restriction; earlier last occurrence in the equatorial region than mid- high latitudes; and/ or absence due to lower resolution sampling of the studied interval.

5.2.3. Zone 3. Definition. The base of the zone is defined by the LO of A. gippingensis. The top of the zone is defined by the FO of Homotryblium tenuispinosum.

Other useful bioevents. Typical of this zone is the presence of Wilsonidium nigeriaense and rare abundance of Apectodinium spp. Also present are Hafniasphaera hyalospinosa, Kallosphaeridium spp., Polysphaeridium spp., and Thalassiphora delicata.

Age range. Late Paleocene (early Thanetian), ODP Hole 959D, 6.58 m thick from sample CIG11 (828.72 mbsf) to sample CIG10 (822.14 mbsf). The lower boundary correlates with the bottom of calcareous nannoplankton subzone CP7 and the upper boundary is close to the top of subzone CP7.

Comments. The FO of H. tenuispinosum has been observed in equatorial region

(early Thanetian, 57 Ma, Williams et al., 2004). Furthermore, Iakovleva et al. (2001) and

Crouch et al. (2003) confirmed the FO of Homotryblium spp. in calcareous nannoplankton

NP6/8 in Kazakhstan and southern Tethys sections. Slimani et al. (2016) recorded the FO of Homotryblium tenuispinosum at the basal of the Thanetian stage in the Tahar and Sekada sedtions in Morocco. Bankole et al. (2007) and Mbesse et al. (2012) identified the same species in the Thanetian of the Dahomey Basin (southwestern Nigeria) and Douala Basin

(Cameroun), respectively. In addition, Wilsonidium nigeriaense has been observed and indicates a Late Paleocene (Jan du Chêne and Adediran, 1985; Mbesse et al., 2012).

Apectodinium spp. occurred in rare percentages during the early Thanetian in low latitude regions (Brinkhuis et al., 1994; Bujak and Brinkhuis, 1998).

5.2.4. Zone 4. Definition. The base of the zone is defined by the FO of

Homotryblium tenuispinosum. The top of the zone is defined by the LO of Apectodinium spp.

Other useful bioevents. Typical dinoflagellate cysts in this zone are

Adnatosphaeridium ivoriense sp. nov., Adnatosphaeridium multispinosum, Eocladopyxis furculum sp. nov., Homotryblium spp., Kallosphaeridium spp., and Polysphaeridium spp.

An acme occurrence of Impletosphaeridium spp. is recorded in the lower part followed by common to frequent abundance of Apectodinium spp. through zone 4.

Age range. Latest Paleocene (middle-late Thanetian), ODP Hole 959D, 19.02 m thick, from sample CIG10 (822.14 mbsf) to sample CIG5 (803.12 mbsf). The lower boundary is closely correlated to the base of calcareous nannoplankton subzone CP8a and the upper boundary correlates with the middle of subzone CP8b.

Comments. Consistent abundance of Apectodinium (15%) is represented mostly through zone 4 and this notable occurrence of Apectodinium spp. has been related to the late Thanetian in both low and high latitudes (Bujak and Brinkhuis, 1998; Crouch et al.,

2003; Guasti et al., 2005; Harding et al., 2011; Slimani et al., 2016). Apectodinium spp. has earliest LO in the late Thanetian in the studied interval compared to Ypresian in other studies in low, mid or high latitudes (Crouch et al., 2014; Slimani et al., 2016). We suggest that the reason may be paleoenvironmental restrictions or that the LO has not been sampled in the early Eocene of the studied interval. The LOs of several dinoflagellate cyst species concentrated in the upper part of this zone in ODP Hole 959D (Fig. 3) indicated either condensed horizons or hiatuses in this part of the section, as noticed in previous studies of nearby ODP Leg 159 sites (e.g. Shafik et al., 1998).

5.2.5. Zone 5. Definition. The base of the zone is defined by the LO of

Apectodinium spp. The top of the zone is not defined in this study.

Other useful bioevents. This zone is characterized by an abundance of the following taxa: Adnatosphaeridium multispinosum, Cordosphaeridium spp., Homotryblium tenuispinosum, Muratodinium fimbriatum, and Polysphaeridium spp.

Age range. Late Paleocene-Early Eocene (latest Thanetian-earliest Ypresian), ODP

Hole 959D, from sample CIG5 (803.12 mbsf) to sample CIG1 (776.32 mbsf). The lower boundary correlates with the middle part of calcareous nannoplankton subzone CP8b.

Comments. The presence of various taxa such as Adnatosphaeridium multispinosum, Cordosphaeridium gracile, Homotryblium tenuispinosum, Muratodinium fimbriatum, and Polysphaeridium spp. characterizes the Late Paleocene-Early Eocene as indicated in previous West African studies and elsewhere (Jan du Chêne and Adediran,

1985; Jan du Chêne, 1988; Williams and Bujak, 1985; Stover et al., 1996; Bankole et al.,

2007; Mbesse et al., 2012). The absence of some biostratigraphically important species in the Ypresian, such as Deflandrea phosphoritica, and high abundance of Apectodinium spp.

(Williams et al., 2004; Slimani et al., 2016) may be due to the few number of samples examined in the studied interval (only three samples, CIG1, CIG2, CIG3; Fig. 3).

5.3. PALEOENVIRONMENTAL RECONSTRUCTION

Palynomorph preservation varies from poor to excellent and recovery is generally good. Terrestrial palynomorphs (pollen and spores) are common in most samples but they are generally less abundant than dinoflagellate cysts. They typically represent percentages between 4% and 34% in all the samples. The bottom of the section has generally higher percentage of terrestrial palynomorphs than the middle and top of the section (Fig. 5). Some taxa and/or groups of morphologically related taxa typically represent 80-90% of the dinoflagellate cyst assemblage (Table 2). Their quantitative distribution (only in samples with >100 dinoflagellate cyst specimens) is shown in Fig. 5.

Spiniferites spp. dominate the dinoflagellate cyst assemblage (mostly subspecies of

S. ramosus) and represent 10% to 96% of the assemblage in all samples. In addition, the

Operculodinium group is present in every sample in percentages mostly higher than 10%.

In order to describe the studied interval in detail, we have interpreted it as follows: Early

Paleocene (Danian), Late Paleocene (Selandian and Thanetian), and earliest Eocene

(Ypresian) (Fig. 5).

5.3.1. Early Paleocene (Danian, 867.60-860.70 mbsf). High percentages of the

Spiniferites group (35-45%) and Operculodinium spp. (10-30%), and low percentages of the Glaphyrocysta group (<5%) and Tectatodinium spp. (<15%), are recorded in the lower part of the section. Extant specimens of Operculodinium can usually be found in a variety of environments ranging from oceanic to restricted marine (Brinkhuis, 1994); however,

23 they are often recorded in more offshore settings due to transportation (Wall et al., 1977;

Harland, 1983; Edwards and Andrle, 1992; Brinkhuis, 1994). Specimens of Spiniferites and Operculodinium are considered as indicators of an open marine environment (Schrank,

1984; Brinkhuis and Zachariasse, 1988; Eshet et al., 1992; Brinkhuis and Schiøler, 1996;

Brinkhuis et al., 1998; Slimani et al., 2010). A distinctive occurrence of Palaeocystodinium spp. (~30%) (mainly P. glozowense) is recorded in sample CIG17 (864.06 mbsf).

Fig. 4. Proposed Dinoflagellate cyst zones using the last occurrence (LO) or first occurrence (FO) of dinoflagellate cyst taxa in the Early Paleogene interval.

Table 2. Morphological taxa and groups representing 80-90% of the dinoflagellate cyst assemblage in ODP Hole 959D.

Morphological Taxa Groups 1 Adnatosphaeridium spp. (mainly A. multispinosum)

2 Cordosphaeridium group (including Cordosphaeridium spp., Ifecysta spp., Damassadinium spp. and Lanternosphaeridium spp.)

3 Polysphaeridium group (Polysphaeridium spp. and Eocladopyxis spp.)

4 Spiniferites group (Spiniferites spp., Achomosphaera spp. and Hafniasphaera spp. 5 Apectodinium spp.

6 Glaphyrocysta group (Glaphyrocysta spp. and Areoligera spp.)

7 Operculodinium spp.

8 Batiacasphaera spp.

9 Tectatodinium spp. (typically T. nigeriaense sp. nov.)

10 Palaeocystodinium spp. (typically P. golzowense)

11 Impletosphaeridium spp.

Since Palaeocystodinium usually represents nearshore, tropical-subtropical and nutrient-rich environments (Lentin and Williams, 1980; Berggren et al., 2012), its occurrence with marine environment specimens, such as Spiniferites spp., Operculodinium spp., and Tectatodinium spp., in the lower part may suggest a rich nutrient water discharge to the area of deposition.

5.3.2. Late Paleocene (Selandian, 851.68-828.72 mbsf). An acme of

Glaphyrocysta group (80%, all Areoligera gippingensis) is recorded in sample CIG15

(851.68 mbsf). This high abundance of A. gippingensis is indicative of high energetic inner neritic environment (Powell et al., 1996; Sluijs and Brinkhuis, 2009; Iakovleva, 2011).

Previous studies have related Areoligera to transgressive events in other regions (Firth,

1993; Sluijs and Brinkhuis, 2009; Slimani et al., 2010). In sample CIG14 (844.35 mbsf)

Tectatodinium spp. (mainly T. nigeriaense sp. nov.) is superabundant (~50%);

Tectatodinium is a warm water genus that can be found in offshore sediments, from inner to outer neritic environment (Wall et al., 1977; Harland, 1983; Head, 1994). Therefore, the co-occurrence of Areoligera and Tectatodinium is indicative of marine environment with low terrestrial input (6%). Furthermore, the presence of Impagidinium celineae and

Thalassiphora delicata (Fig. 3) indicates an oceanic environment for this part of the interval (Brinkhuis et al., 2003; Sluijs et al., 2005; Udeze and Oboh-Ikuenobe, 2005). High contents of Batiacasphaera spp. (~25%) with Impagidinium spp. (~5%) have been noted in this interval (Fig. 3), which were also observed by Brinkhuis and Zachariasse (1988) in

NW Tunisia and interpreted as an offshore environment. High abundance of

Glaphyrocysta spp. are recorded in sample CIG11 (828.72 mbsf), specimens of these genera are common in warm, open marine, inner neritic environment with high energy

(Islam, 1984; Brinkhuis and Zachariasse, 1988; Köthe, 1990; Eshet et al., 1992; Brinkhuis,

1994; Slimani et al., 2010; Digbehi et al., 2012). The transition from offshore

(Tectatodinium) to nearshore taxa (Glaphyrocysta) suggests fluctuations in sea levels.

Species of Apectodinium (<5%), Adnatosphaeridium (15%) and Polysphaeridium (<10%) have their FOs in the section through the upper Selandian-lower Thanetian (831.64-828.72 mbsf). Jan du Chêne and Adediran (1985) recorded Adnatosphaeridium spp. in association with Apectodinium spp. in the Paleogene of Nigeria.

5.3.3. Late Paleocene (Thanetian, 822.14-799.88 mbsf). Operculodinium spp. (5-

20%) and Spiniferites group (15-65%) dominate the samples in this interval. An acme of

Impletosphaeridium spp. (~50%) is observed in sample CIG10 (822.14 mbsf). Continuous occurrence of Batiacasphaera spp., Impagidinium spp., Tectatodinium and Thalassiphora spp. is a sign of outer neritic-oceanic influence (Wall et al., 1977; Edwards and Andrle,

1992, Fig. 3). In addition, Apectodinium has its maximum abundance (15%, Fig. 5) in this interval. While specimens of Apectodinium are more common in nearshore lower salinity waters, they also occur in inner to shallow outer neritic environment with strong nutrient availability (Guasti et al., 2006; Prasad et al., 2006; Sluijs and Brinkhuis, 2009). The abundance of species of this genus is related to the Paleocene/Eocene Thermal Maximum

(PETM) and can be used to identify the Thanetian (Powell et al., 1996; Mudge and Bujak,

1996). Numerous palynological studies, mainly of mid and high latitude localities, have documented an Apectodinium acme (40% increase in the dinoflagellate cyst assemblage) during the PETM, and related this increase to global climatic warming (Bujak and

Brinkhuis, 1998; Iakovleva et al. 2001; Crouch et al., 2003, 2014; Sluijs and Brinkhuis,

2009). Apectodinium appeared in the study area at the Selandian-Thanetian boundary, and substantially increased in abundance during the late Thanetian, apparently recording episodes of intense global climatic warming. In the studied interval, Apectodinium spp. consists mainly of Apectodinium homomorphum (~90% of the specimens), and

Apectodinium paniculatum and Apectodinium quinquelatum (both ~10%); Apectodinium augustum, the biostratigraphic important mid-high latitude species, is absent.

Fig. 5. Quantitative distribution of selected dinoflagellate cysts in samples with >100 recovered specimens in the Paleocene-Early Eocene interval. Abundances of terrestrial palynomorphs (e.g. pollen and spores) are also shown.

Many factors may result in the abundance of the Apectodinium spp. as a synchronous event during the late Thanetian-early Ypresian age in low, mid-high latitudes.

These factors include low salinity, elevated sea-surface temperature and nutrients availability (Prasad et al., 2006; Sluijs et al., 2005; Sluijs and Brinkhuis, 2009). The presence of this unique acme in a very short time interval over wide latitudinal regions indicates a major change in the sea surface temperature and paleoenvironmental conditions in the northern and southern hemispheres (Prasad et al., 2006; Crouch et al., 2001).

In the present study, no remarkable acme interval (>23%) of Apectodinium was recorded; only common to frequent occurrence (not exceeding 15%) was observed during the Late Paleocene. We suggest that an environmental constraint may be one of the reasons for this observation because this ODP Hole 959D section is characterized mainly by offshore taxa (e.g. Impagidinium spp., Operculodinium spp., Spiniferites spp.,

Tectatodinium spp., and Thalassiphora spp.). However, we also propose two other reasons that may be responsible for the absence of the Apectodinium acme in this study: lack of samples in the late Thanetian between CIG6 (806.30 mbsf) and CIG3 (793.35 mbsf) (Fig.

5), and the condensed horizons or hiatuses in this part of the section (CIG 6, Fig. 3). The

Polysphaeridium group, which is considered as an indicator of restricted marine environment, usually lagoonal (Sluijs and Brinkhuis, 2009), is present in this interval

(<20%, mainly Eocladopyxis spp.). Species of Apectodinium, Batiacasphaera,

Palaeocystodinium and Tectatodinium are not recorded in sample CIG14 (799.88 mbsf, end of the Paleocene).

5.3.4. Earliest Eocene (Ypresian, 793.35-776.32 mbsf). The Spiniferites group represents 92-96% in samples CIG1 (776.32 mbsf) and CIG3 (793.35 mbsf) (mainly S.

29 ramosus subsp.) but constitutes 23% in sample CIG2 (787.35 mbsf). However,

Adnatosphaeridium is abundant (26%) in sample CIG2 (mainly A. multispinosum). Since

Adnatosphaeridium is typically found in inner neritic shallow marine environment (Crouch,

2001; Sluijs et al., 2005; Iakovleva, 2011), its occurrence alongside Spiniferites spp.,

Cordosphaeridium spp. (Figs. 3 and 5) suggests nearshore to open marine environments

(Islam, 1984; Brinkhuis and Zachariasse, 1988; Köthe, 1990).

6. SYSTEMATIC PALEONTOLOGY

Four new taxa have been recorded and described below. They are

Adnatosphaeridium ivoriense sp. nov., Diphyes digitum sp. nov., Eocladopyxis furculum sp. nov., and Tectatodinium nigeriaense sp. nov. The DINOFLAG2 database (Fensome et al., 2008) was used for classifying the dinoflagellate cysts. Systematic descriptions follow

Fensome et al. (1993) to the subclass level and terminologies follow Evitt (1985) and

Williams et al. (2000).

Division DINOFLAGELLATA (Bütschli, 1885) Fensome et al., 1993

Subdivision DINOKARYOTA Fensome et al., 1993

Class DINOPHYCEAE Pascher, 1914

Subclass PERIDINIPHYCIDAE Fensome et al., 1993

Order GONYAULACALES Taylor, 1980

Suborder GONYAULACINEAE Norris, 1978 (autonym)

Genus Adnatosphaeridium Williams and Downie, 1966

Type: Adnatosphaeridium vittatum Williams and Downie, 1966

Adnatosphaeridium ivoriense sp. nov. Plate I, 1-5

Holotype: ODP Hole 959D, 803.12 mbsf, sample CIG5, slide MST-1915-S13, EF

M11/3, Late Paleocene. Plate I; 1-4.

Paratype: ODP Hole 959D, 806.30 mbsf, sample CIG6, slide MST-1915-S18, EF

J25/2, Late Paleocene. Plate I; 5.

Type locality: Upper Paleocene of ODP Hole 959D, Côte d’Ivoire-Ghana

Transform Margin, West Africa. Lithological unit III (Shipboard Scientific Party, 1996).

Etymology: After the country of Côte d’Ivoire.

Synonymy: Adnatosphaeridium sp. A (Jan du Chêne and Adediran, 1985) plate 23,

1-6.

Diagnosis: A species of Adnatosphaeridium with short processes, which are connected by distal trabeculae that are finely perforate.

Description: Skolochorate cyst with a subspherical body. The processes are simple, intratabular, arranged in soleate or annulate groups that reflect the paratabulation of the cyst. Each complex composes of very fine and short processes, which are united distally by trabeculae that are joined to each other and look distally like a reticulate or a finely perforate membrane. The species is characterized by a well-developed antapical proturbance and the sulcus is offset to the left (Plate I; 2), this feature would agree with the areoligeran nature of this genus (Fensome et al., 1993). Archaeopyle is apical type tA; operculum free.

Dimensions: Holotype: width x length: 80 x 70 m; length of processes 15 m.

Paratype: width x length: 57 x 71 m; length of processes 10-14 m. 2 specimens measured.

Stratigraphic range: Adnatosphaeridium ivoriense sp. nov. was observed in ODP

Hole 959D from 803.12 mbsf to 806.3 mbsf (Late Paleocene). This new species is restricted to the late Thanetian-early Ypresian as recorded from a previous study of the Imo

Formation in Nigeria by Jan du Chêne and Adediran (1985). Adnatosphaeridium ivoriense sp. nov. is rare (2 specimens) and has a relatively short stratigraphic range in the studied interval. This observation is similar to that reported by Jan du Chêne and Adediran (1985) who recorded three specimens of this species in the Late Paleocene-Early Eocene interval.

Comparison: Adnatosphaeridium ivoriense sp. nov. differs from other species of this genus by its shorter processes. Processes are united by distal trabecula, which are finely perforate and wider than those of other species. Adnatosphaeridium? membraniphorum

(Jan du Chêne and Adediran, 1985) and Adnatosphaeridium multispinosum (Williams and

Downie, 1966) both have longer processes (20-36 m) with central body diameters 56-68

m to 54-76 m, respectively. In addition, the former has clearer perforations than

Adnatosphaeridium ivoriense sp. nov., while the later has only single trabecula of variable breadth without any perforations. A. vittatum (Williams and Downie, 1966) has processes showing considerable variation in breadth (up to 20 m) with length up to 30 m, central body diameter 35-48 m and distally united by interconnecting ribbon-like trabecula, which are broad and membranous. In A. robustum (Morgenroth, 1966) length of processes is up to 26 m with acuminate spines occasionally present on the trabecula without perforations like the new species. A. williamsii (Islam, 1983) differs from

Adnatosphaeridium ivoriense sp. nov. in having filiform extremities (up to 20 m process length, 43-57 m body diameter). Both A. buccinum (Hultberg, 1985, length of processes

22 m, cyst diameter 40 m) and A. caulleryi (Deflandre, 1939, length of processes 10-17

m, cyst diameter 45 m) differ from the new species by buccinate processes that are connected with distal trabecula without perforation. A. densifilosum (Cookson and

Eisenack, 1974) has denser fenestrate trabecula with very long processes (up to 45 m) and

45 m cyst diameter. Small filiforms at the trabecula are the major characteristics of A. filiferum (Cookson and Eisenack, 1958, up to 50 m length of processes and 104 m cyst diameter). Glaphyrocysta exuberans (Deflandre and Cookson, 1955), G. microfenestrata

(Bujak, 1976) and G. vicina (Eaton, 1976) do not have process complexes in the mid- ventral and mid-dorsal areas. The processes of Adnatosphaeridium ivoriense sp. nov. are not connected proximally by basal ridges that mainly characterize Areoligera spp.

Genus Diphyes Deflandre and Cookson, 1955

Type: Diphyes colligerum (Deflandre and Cookson) Cookson, 1965

Diphyes digitum sp. nov. Plate I; 6-10; plate II; 1,2

Holotype: ODP Hole 959D, 860.7 mbsf, sample CIG16, slide MST-1931-S1, EF

H33, Early Paleocene. Plate I; 6.

Paratypes: Paratype 1. ODP Hole 959D, 860.7 mbsf, sample CIG16, slide MST-

1931-S1, EF E30, Early Paleocene. Plate I; 7. Paratype 2. ODP Hole 959D, 860.7 mbsf, sample CIG16, slide MST-1931-S1, EF R30/4, Early Paleocene. Plate I; 8.

Type locality: Lower Paleocene of ODP Hole 959D, Côte d’Ivoire-Ghana

Transform Margin, West Africa. Lithological unit III (Shipboard Scientific Party, 1996).

Etymology: From the Latin “digitus”, meaning finger, with reference to finger-like process endings.

Diagnosis: A species of Diphyes having slender processes with finger-like endings.

The antapical process is long and slender, sometimes tapering to a point.

Description: Chorate cysts, subspherical to ovoidal. Processes exceed 50, with one large process in the antapical to four processes in the other plates. The processes may be simple or bifurcate and commonly having 3 to 5 further branches distally. In appearance the processes are reminiscent of a hand. Some processes are connected halfway along their length. The antapical process is longer, commonly tapering but sometimes expanded and branched. The archaeopyle is typically precingular P3” (Plate I; 6, 7, 9, 10) or apical (4A) with an attached operculum (Plate I; 8). However, one specimen (Plate II; 1, 2) had a combination precingular-apical type (4A) P3” with a detached operculum. Several other studies have suggested that Diphyes spp. display a variation in archaeopyle type (Goodman and Witmer, 1985; Fauconnier and Masure, 2004; Fensome et al., 2009), generally apical with formula (4A) but may be P3” or (4A) P3”.

Dimensions: Holotype: width x length: 40 x 45 m, length of processes 15 m, length of antapical process 20 m. Paratype 1: width x length: 30 x 40 m, length of processes 13 m, length of antapical process 20 m. Paratype 2: width x length: 40 x 45

m, length of processes 12 m, length of antapical process 20 m. Average dimensions: length: 40-45 m, width: 30-40 m, length of antapical process: 20-25 m and length of processes: 10-15 m. 18 specimens measured.

Stratigraphic range: Diphyes digitum sp. nov. was observed in ODP Hole 959D from 860.7 mbsf to 867.6 mbsf (Early Paleocene). The new species has common occurrence, a short stratigraphic range, and its last occurrence in the Danian; its first occurrence is not recorded in this study. Jan du Chêne (1988), Willumsen et al. (2004), and

Antolinez and Oboh-Ikuenobe (2007) recorded somewhat similar specimens with bifid rather than finger like processes in Upper Cretaceous-Danian sections in West African.

Comparison: Diphyes digitum sp. nov. differs from other species of the genus in having processes that distally split into three to five branches. Diphyes colligerum

(Deflandre and Cookson, 1955) has finely serrate or entire processes but lacks furcation.

Processes in Diphyes sp. 1 (Jan du Chêne, 1988; Willumsen et al., 2004) and D. bifidum

(Antolinez and Oboh-Ikuenobe, 2007) are bifurcate. Diphyes recurvatum (May, 1980) has fibrous processes with distally trifurcate and recurved prongs, whereas Diphyes digitum sp. nov. has a combination of different types of processes that are simple or bifurcate commonly with 3 to 5 further branches distally. In addition, the large antapical process in

Diphyes recurvatum has lateral tubules and spines at the distal end, which is not present in

Diphyes digitum sp. nov.

Genus Tectatodinium Wall, 1967

Type: Tectatodinium pellitum Wall, 1967

Tectatodinium nigeriaense sp. nov. Plate III; 1-11

Holotype: ODP Hole 959D, 844.35 mbsf, sample CIG14, slide MST-1928-S1, EF

G26, Early Paleocene. Plate III; 1.

Paratypes: Paratype 1. ODP Hole 959D, 844.35 mbsf, sample CIG14, slide MST-

1928-S1, EF D30/3, Early Paleocene. Plate III; 2. Paratype 2. ODP Hole 959D, 844.35 mbsf, sample CIG14, slide MST-1928-S1, EF M28/4, Early Paleocene. Plate III; 3.

Type Locality: Lower Paleocene of ODP Hole 959D, Côte d’Ivoire-Ghana

Transform Margin, West Africa. Lithological unit III (Shipboard Scientific Party, 1996).

Etymology: From the Latin “nigeriaense”, derived from the country of Nigeria, where this species was first observed by Jan du Chêne (1988).

Synonymy: Xeniocodinium sp. cf. X. rugulatum (Jan du Chêne, 1988) Plate 17; 1-8, and Tectatodinium rugulatum (Masure et al., 1998) plate 3; 10.

Diagnosis: A species of Tectatodinium with spongy luxuria and characterized by a thick wall, thread like projections and large size.

Description: Spherical to ovoid cyst with a slight apical protuberance, which is clearer in some specimens than others. The wall consists of an inner pedium, about 0.1 µm thick and an outer luxuria comprised of fine projecting fibrils, giving the surface a fluffy appearance. Archaeopyle is precingular, typically type P3’’.. The only indications of paratabulation are the irregular margins of the archaeopyle. Operculum is free and is occasionally found within the cyst (Plate III; 7, 8).

Dimensions: Holotype: width x length: 70 x 85 m, wall thickness 6 m. Paratype

1: width x length: 60 x 70 m, wall thickness 7 m. Paratype 2: width x length: 68 x 70

m, wall thickness 5 m. Average dimensions: length: 70-98 m, width: 60-92 m, wall thickness: 4-8 m. More than 500 specimens measured.

Stratigraphic range: Tectatodinium nigeriaense sp. nov. was observed in ODP Hole

959D from 817.3 mbsf to 867.6 mbsf (Early Paleocene to Late Paleocene). The stratigraphic range of the new species is relatively long in the studied interval; however, we did not observe it between 844.25 and 817.3 for some unknown reason(s). The FO is recorded from the Danian age, while the LO is observed in the early Thanetian. It has a frequent to superabundant occurrence through the Paleocene. Jan du Chêne (1988) recorded Xeniocodinium sp. cf. X. rugulatum in the Danian rocks of Madeleines Formation in Senegal.

Comparison: Tectatodinium nigeriaense sp. nov. differs from Tectatodinium pellitum (Wall, 1967) in its wall structure and cyst size. The wall in the new species is fluffier than that of Tectatodinium pellitum. In Tectatodinium nigeriaense sp. nov., the cyst looks like a piece of cotton with thread-like processes. The luxuria is comprised of very fine projections, which are difficult to recognize separately, and has a compacted appearance (Plate III; 9, 10, 11). In contrast, the luxuria of Tectatodinium pellitum is loose, open with numerous, finely interwoven fibrils that give a roughened texture to the cyst

(Plate III; 12, 13). Tectatodinium nigeriaense sp. nov., is also larger than Tectatodinium pellitum: 60-98 m vs. 36-51 m.

Tectatodinium nigeriaense sp. nov. has an older stratigraphic range (Danian) than the FO of Tectatodinium pellitum noted in the Lower Eocene deposits of northern Germany

(Fechner and Mohr, 1988; Head, 1994). An acme of Tectatodinium nigeriaense sp. nov. was recorded from the Selandian rocks in ODP Hole 959D. Furthermore, an earlier appearance of Tectatodinium pellitum was recorded in our study at the Selandian/Thanetian boundary.

Suborder GONIODOMINEAE Fensome et al., 1993

Genus Eocladopyxis Morgenroth, 1966

Type: Eocladopyxis peniculata Morgenroth, 1966

Eocladopyxis furculum sp. nov. Plate II; 3-10

Holotype: ODP Hole 959D, 812.34 mbsf, sample CIG7, slide MST-1915-S21, EF

N29, Late Paleocene. Plate II; 3.

Paratypes: Paratype 1. ODP Hole 959D, 812.34 mbsf, sample CIG7, slide MST-

1915-S21, EF H27/1, Late Paleocene. Plate II; 4. Paratype 2. ODP Hole 959D, 812.34 mbsf, sample CIG7, slide MST-1915-S21, EF N39/2, Late Paleocene. Plate II; 5.

Type Locality: Upper Paleocene of ODP Hole 959D, Côte d’Ivoire-Ghana

Transform Margin, West Africa. Lithological unit III (Shipboard Scientific Party, 1996).

Etymology: From the Latin: “furcula”, meaning little fork, with reference to its short processes that expand distally.

Synonymy: Eocladopyxis sp. A (Edwards, 2001) plate 2; 7.

Diagnosis: A species of Eocladopyxis with numerous short processes that are distally open with a serrate or spinate margin.

Description: Proximochorate cyst, spherical to subspherical, moderately to strongly compressed dorso-ventrally, bowl-shaped when the operculum is not attached; with numerous, short nontabular processes, more than 10 per plate, that are open and expanded distally with a serrate or spinose margin. Paratabulation gonyaulacacean, indicated on hypocyst by narrow parasutural grooves. Plates 1”’, 2”’, 3”’, 4”’, 5”’ and 6”’are discernible on the ventral and dorsal side of the hypocyst and all the plates are discernible on the operculum (4Aa + 6P), which consists of the four apical plates that remain attached to each and the individual precingular plates.

Dimensions: Holotype: width x length with operculum: 63 x 72 m, length without operculum: 35 m, length of processes up to 5 m. Paratype 1: width x length with operculum: 60 x 65 m, length without operculum: 35 m, length of processes: 4 m.

Paratype 2: width x length without operculum: 55 x 25 m, length of processes: 5 m.

Average dimensions: length with operculum: 65-70 m, length without operculum: 30-40

m, width: 60-65 m, Length of processes: 3-5 m. 29 specimens measured

Stratigraphic range: For the studied interval, Eocladopyxis furculum sp. nov. was observed only in ODP Hole 959D at 812.34 mbsf (Late Paleocene) where it has common abundance. However, the new species was also recorded in the Oligocene sediments at

411.71 mbsf (unpublished data).

Comparison: Eocladopyxis furculum sp. nov. differs from the other species of the genus by its short and distally expanded processes that are open distally and have serrate or spinose margins. Eocladopyxis furculum sp. nov is similar to Eocladopyxis peniculata

(Morgenroth, 1966) in the lengths of the processes, which are 3-5 m in the former and 3-

7 m in the latter. However, the distal ends of the processes differ in the two species because Eocladopyxis peniculata has distally pointed and closed acuminate processes, while Eocladopyxis furculum sp. nov has serrate or spinose processes (Plate II; 7,8).

Eocladopyxis tessellata (Liengjarern, 1980) has longer (8-15 m), bi- to multifurcate processes with spinose distal end. Eocladopyxis furculum sp. nov. is similar to

Eocladopyxis sp. A. (Edward, 2001), but has shorter processes. Species of

Polysphaeridium (Davey and Williams, 1966) and Homotryblium (Davey and Williams,

1966) are also chorate cysts with epicystal archaeopyle and compound opercula. However,

Homotryblium has one process per plate, and Polysphaeridum lacks the parasutural groves that charaterize the hypocyst in Eocladopyxis (Stover and Evitt, 1978; Liengjarern, 1980).

Plate I. Photomicrographs no 1 of dinoflagellate cysts. Figs. 1-5. Adnatosphaeridium ivoriense sp. nov. Figs. 1-4. Holotype. CIG5, EF M11/3. Fig. 1. Dorsal view, high focus shows short processes that are united distally by reticulate trabeculae. Fig. 2. Ventral view, low focus illustrates the process complexes. Figs. 3, 4. Dorsal view, high focus illustrates the reticulate trabeculae at the distal side of the processes. Fig. 5. Paratype. Uncertain view, mid focus, CIG6, EF J25/2. Figs. 6-10. Diphyes digitum sp. nov. Fig. 6. Holotype. Left lateral view, low focus, CIG16, EF H33. Note the finger-like processes. Fig. 7. Paratype 1. Left lateral view, mid focus, CIG16, EF E30. Fig. 8. Paratype 2. Uncertain view, high focus, CIG16, EF R30/4. Specimens illustrate long, wide and pointed antapical process. Fig. 9. Antapical view, mid focus, CIG16, EF F40; showing the wide antapical process. Fig. 10. Uncertain view, low focus, CIG16, EF F40; note the long and slender processes.

Plate II. Photomicrographs no 2 of dinoflagellate cysts. Figs. 1, 2. Diphyes digitum sp. nov. Fig. 1. Dorsal view, low focus, CIG18, EF L21/3, illustrates the combination archaeopyle. Fig. 2. Ventral view, mid focus, CIG18, EF L21/3, note the slender processes with finger- like processes. Figs. 3-10. Eocladopyxis furculum sp. nov. Fig. 3. Holotype. Ventral view, high focus, CIG7, EF N29. Specimen shows whole cyst with attached operculum and paratabulation especially on the hypocyst. Fig. 4. Paratype 1. Ventral view, mid focus, CIG7, EF H27/1. Note wide isthmus (connection) between the epicyst and hypocyst. Fig. 5. Paratype 2. Uncertain view, high focus, CIG7, EF N39/4. Specimen illustrates nontabular short processes with expanding terminations. Fig. 6. Ventral view, high focus, CIG7, EF L32. Note the strongly dorso-ventrally compressed cyst with epicystal archaeopyle. Figs. 7,8. CIG7, EF N39/4 (Fig. 7) and EF G33/3 (Fig. 8). Close up view illustrating the processes. Figs. 9-10. CIG7, EF G33/3 (Fig. 9) and EF E31/4 (Fig. 10). Specimens illustrate the moderate dorso–ventral compression with bowl shape when the operculum is not attached.

Plate III. Photomicrographs no 3 of dinoflagellate cysts. Figs. 1-8. Tectatodinium nigeriaense sp. nov. Fig. 1. Holotype. Dorsal view, high focus, CIG14, EF G26. Note the large cyst with a slight apical protuberance and thick wall. Fig. 2. Paratype 1. Dorsal view, low focus, CIG14, EF D30/3. Fig. 3. Paratype 2. Dorsal view, high focus, CIG14, EF M28/4. Specimens show the precingular archaeopyle (the only indication of paratabulation) and the slight protuberance. Fig. 4. Dorsal view, high focus, CIG14, M38/4. Fig. 5. Dorsal view, low focus, CIG14, 5-7, EF L43. Fig. 6. Dorsal view, high focus, CIG14, EF G38/1. Note the fluffy texture of the wall. Fig. 7. Dorsal view, low focus, CIG14, 5-7, EF T41. Fig. 8. Dorsal view, low focus, CIG14, 5-7, EF T21/4. Specimens have operculum within the cyst and thick wall. Figs.9-11. CIG14, EF S26/3 (Fig. 9), EF O33/4 (Fig. 10) and EF S26/3 (Fig. 11). Close-up view of the wall. Figs. 12, 13. Tectatodinium pellitum. Fig. 12. Dorsal view, low focus, CIG13, EF L23. Specimen shows the precingular archaeopyle and the wall. Fig. 13. Ventral view, high focus, CIG13, EF L23. Note the rough texture of the surfa

Plate IV. Photomicrographs no 4 of dinoflagellate cysts Fig. 1. Adnatosphaeridium? membraniphorum. Dorsal view, low focus, CIG5, EF H29/4. Fig. 2. Adnatosphaeridium multispinosum. Ventral view, high focus, CIG11, EF W41/3. Figs. 3-5. Apectodinium spp. Fig. 3. Apectodinium homomorphum. Left lateral view, high focus, CIG10, EF N41/3. Fig. 4. Apectodinium paniculatum. Right lateral view, mid focus, CIG10, EF G30/4. Fig. 5. Apectodinium quinquelatum. Uncertain view, mid focus, CIG10, EF K29/3. Fig. 6. Areoligera coronata. Ventral view, low focus, CIG13, EF P25/1. Fig. 7. Areoligera gippingensis. Ventral view, low focus, CIG15, EF T39/4. Fig. 8. Areoligera tauloma. Ventral view, high focus, CIG13, EF O35. Figs. 9, 10. Batiacasphaera spp. Fig. 9. Uncertain view, high focus, CIG12, EF G22. Fig. 10. Apical view, low focus, CIG13, EF D36/2. Fig. 11. Cerodinium diebelii. Dorsal view, low focus, CIG18, EF R42/3. Fig. 12. Cordosphaeridium exilimurum. Ventral view, high focus, CIG2, EF G42. Fig. 13. Cordosphaeridium fibrospinosum. Ventral view, high focus, CIG12, EF G32/1.

Plate V. Photomicrographs no 5 of dinoflagellate cysts. Fig. 1. Cordosphaeridium gracile. Dorsal view, low focus, CIG4, EF U44/2. Fig. 2. Damassadinium californicum. Left lateral view, mid focus, CIG18, EF K35. Fig. 3. Deflandrea oebisfeldensis. Dorsal view, low focus, CIG9, EF N40. Fig. 4. Diphyes colligerum. Uncertain view, high focus, CIG13, EF E37/1. Fig. 5. Eocladopyxis peniculata. Ventral view, low focus, CIG6, EF P32/1. Fig. 6. Exochosphaeridium bifidum. Dorsal view, mid focus, CIG18, EF L37/4. Fig. 7. Glaphyrocysta divaricata. Ventral view, high focus, CIG13, EF F40/2. Fig. 8. Glaphyrocysta ordinata. Oblique dorsal view, low focus, CIG11, EF L17/1. Fig. 9. Hafniasphaera hyalospinosa. Right lateral view, high focus, CIG9, EF D28/2. Fig. 10. Hafniasphaera septata. Left lateral view, low focus, CIG7, EF F36. Fig. 11. Homotryblium abbreviatum. Antapical view, high focus, CIG10, EF P35/3. Fig. 12. Homotryblium tenuispinosum. Uncertain view, high focus, CIG2, EF K25/3.

Plate VI. Photomicrographs no 6 of dinoflagellate cysts. Fig. 1. Ifecysta fusiforma. Dorsal view, high focus, CIG14, EF V10/2. Fig. 2. Ifecysta heterospinosa. Oblique dorsal view, CIG18, EF G26. Fig. 3. Ifecysta lappacea. Left lateral view, mid focus, CIG18, EF R17/2. Fig. 4. Ifecysta pachyderma. Oblique dorsal view, low focus, CIG14, EF C42/3. Fig. 5. Impagidinium celineae. Left lateral view, low focus, CIG10, EF C41/4. Figs. 6, 7. Impletosphaeridium spp. Fig. 6. Uncertain view, mid focus, CIG7, EF B21/4. Fig. 7. Antapical view, high focus, CIG10, EF B20/3. Fig. 8. Kallosphaeridium brevibarbatum. Ventral view, low focus, CIG 6, EF G32/4. Fig. 9. Kallosphaeridium orchiesense. Dorsal view, mid focus, CIG7, EF K23/2. Fig. 10. Kallosphaeridium yorubaense. Uncertain view, low focus, CIG8, EF B20/3. Fig. 11. Melitasphaeridium pseudorecurvatum. Dorsal view, low focus, CIG7, EF G20/1. Fig. 12. Muratodinium fimbriatum. Ventral view, mid focus, CIG4, EF F23/2. Fig. 13. Operculodinium centrocarpum. Dorsal view, mid focus, CIG7, EF F43/1.

Plate VII. Photomicrographs no 7 of dinoflagellate cysts. Figs.1,2. Palaeocystodinium golzowense. Fig.1. Left lateral view, high focus, CIG13, EF Q33/4. Fig.2. Uncertain view, mid focus, CIG10, EF P23/4. Figs.3,4. Polysphaeridium spp. Fig.3. Polysphaeridium congregatum. Uncertain view, mid focus, CIG11, EF N26. Fig.4. Polysphaeridium zoharyi. Ventral view, mid focus, CIG11, EF Q36/3. Figs.5,6. Spiniferella cornuta. Fig.5. Ventral view, mid focus, CIG16, EF F33/2. Fig.6. Ventral view, low focus, CIG16, EF H27/1. Figs.7-9. Spiniferites spp. Fig.7. Spiniferites ramosus. Left lateral view, high focus, CIG7, EF G33/3. Fig.8. Spiniferites mirabilis. Uncertain view, mid focus, CIG14, EF V13/4. Fig.9. Spiniferites pseudofurcatus. Left lateral view, mid focus, CIG13, EF F27. Figs.10,11. Thalassiphora delicata. Fig. 10. Uncertain view, high focus, CIG13, EF Y17/2. Fig.11. Uncertain view, high focus, CIG12, EF M18/4. Fig.12. Thalassiphora sp. cf. T. patula. Right lateral view, high focus, CIG7, EF E21/3. Fig.13. Trichodinium hirsutum. Ventral view, high focus, CIG18, EF N44/4. Fig.14. Wilsonidium nigeriaense. Ventral view, low focus, CIG10, EF G42/2.

7. CONCLUSIONS

(1) Five biostratigraphic zones (zone 1 to zone 5) defined by last or first occurrence

bioevents of dinoflagellate cysts were proposed for the Paleocene-Eocene interval

of ODP Hole 959D. Based on some important bioevents and calibration with

calcareous nannofossils, the zones were dated as follow: zone 1, Danian; zone 2,

Selandian-earliest Thanetian; zone 3, early Thanetian; zone 4, middle-late

Thanetian; and zone 5, late Thanetian to early Ypresian.

(2) Condensed horizons or hiatuses have been observed in the Late Paleocene

sediments in this study based on the LOs of many species within zone zone 4.

(3) Quantitative distribution of dinoflagellate cysts was used to infer the depositional

environments for the studied section. An outer neritic to oceanic environment was

inferred based on the abundances of Impagidinium spp., Operculodinium spp.,

Spiniferites spp. (mainly S. ramosus) and Tectatodinium spp. (typically T.

nigeriaense sp. nov.).

(4) The distal location of ODP Hole 959D likely resulted in the common to frequent

abundance of Apectodinium spp. (with no distinctive peaks) during the late

Thanetian; Apectodinium acmes were recorded in more proximal environments (e.g.

Crouch et al., 2003).

(5) Four new dinoflagellate cyst species were identified. The new species are

Adnatosphaeridium ivoriense sp. nov. (late Thanetian), Diphyes digitum sp. nov.

(Danian), Eocladopyxis furculum sp. nov. (middle Thanetian), and Tectatodinium

nigeriaense sp. nov. (Danian- early Thanetian).

ACKNOWLEDGEMENTS

We acknowledge the Petroleum Research Fund (administered by the American

Chemical Society, Grant 34676-AC8 to Francisca Oboh-Ikuenobe) and the Josephine

Husbands Radcliffe Graduate Scholarship (Department of Geosciences and Geological and

Petroleum Engineering, Missouri University of Science and Technology) for funding this study. Discussions with Drs. Robert A. Fensome, Graham L. Williams and Lucy E.

Edwards on the taxonomy and morphology of dinoflagellate cysts are gratefully appreciated. Constructive and critical reviews by Hamid Slimani and Ali Soliman greatly improved the manuscript.

APPENDIX A.

QUANTITATIVE DINOFLAGELLATE CYST DATA FOR ODP HOLE 959D

817.3 867.6

776.32 787.35 793.35 799.88 803.12 806.30 812.34 814.80 822.14 828.72 830.93 831.64 844.35 851.68 860.70 864.06

Depth (mbsf) Depth

CIG1 CIG2 CIG3 CIG4 CIG5 CIG6 CIG7 CIG8 CIG9

CIG10 CIG11 CIG12 CIG13 CIG14 CIG15 CIG16 CIG17 CIG18 Sample # Sample

Achilleodinium bianii 0 0 0 0 0 0 0 0 0 0 0 1 5 0 0 3 0 2

Achomosphaera spp. 0 0 0 0 0 2 1 2 1 1 0 0 1 5 0 3 0 0 Achomosphaera alcicornu 0 0 0 0 0 0 3 0 0 0 3 0 0 0 0 0 0 0 Achomosphaera ramulifera 0 0 0 1 0 1 0 3 1 5 1 0 0 3 0 3 2 0

Adnatosphaeridium membraniphorum 0 0 0 0 1 1 0 0 0 0 0 0 1 0 0 2 0 0

Adnatosphaeridium multispinosum 0 71 0 0 0 0 0 1 3 12 9 60 0 0 0 0 0 0

Adnatosphaeridium robustum 0 0 0 0 0 0 2 0 0 0 1 7 0 0 0 0 0 0

Adnatosphaeridium ivoriense sp. nov. . 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0

Amphorosphaeridium multispinosum 0 0 0 0 0 0 6 0 1 3 0 0 3 0 0 0 0 0

Andalusiella? sp. 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0

Apectodinium spp. 0 0 0 0 5 45 47 1 44 47 0 1 2 0 0 0 0 0

Apteodinium spp. 0 0 0 0 0 22 1 0 0 0 1 1 1 0 4 0 0 0

Areoligera spp. 0 0 0 0 0 0 0 0 0 0 18 18 2 0 112 3 0 2

Areoligera coronata 0 0 0 0 0 0 0 0 0 0 6 0 1 0 0 0 0 0

Areoligera gippingensis 0 0 0 0 0 0 0 0 0 0 3 9 0 0 136 0 0 0

Areoligera medusettiformis 0 0 0 0 0 0 0 0 0 0 0 4 1 0 0 0 0 0

Areoligera tauloma 0 0 0 0 0 0 0 0 0 0 3 0 1 0 0 0 0 0

Areoligera senonensis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 1

Areoligera cf. A. senonensis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 2

Areoligera sentosa 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0

Areoligera volata 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0

Batiacasphaera spp. 0 0 0 0 0 0 2 11 0 0 4 101 92 4 2 8 2 7

Cerodinium boloniense 0 0 0 0 0 0 0 0 0 0 0 0 0 4 1 2 0 2

Cerodinium diebelii 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2

Cleistosphaeridium spp. 0 0 0 0 0 0 0 1 0 0 2 0 0 0 0 0 0 0

Cordosphaeridium spp. 1 5 1 14 2 0 0 1 5 0 0 0 0 0 0 0 0 0

Cordosphaeridium exilimurum 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cordosphaeridium fibrospinosum 0 0 0 0 0 0 0 0 0 0 0 3 0 1 0 0 0 0

Cordosphaeridium gracile 1 4 1 31 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cyclonephelium spp. 0 1 0 0 0 1 0 0 0 10 0 0 0 0 0 0 0 0

Damassadinium californicum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

Damassadinium heterospinosum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2

Dapsilidinium pastielsii 0 0 0 0 0 0 0 0 0 0 0 0 6 0 0 0 0 0

Deflandrea oebisfeldensis 0 0 0 0 0 2 0 0 4 0 1 0 0 0 0 0 0 0

Diphyes spp. 0 1 0 0 0 1 3 0 1 0 0 1 0 0 0 1 0 0

Diphyes colligerum 0 2 0 1 0 2 0 0 0 0 0 1 4 0 0 0 1 0

Diphyes digitum sp. nov 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 2 6

Diphyes pseudoficusoides 0 1 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0 1

Diphyes spinula 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 1 0

Eocladopyxis peniculata 0 1 8 2 14 18 5 0 5 10 0 3 3 0 0 0 0 0

Eocladopyxis furculum sp. nov 0 0 0 0 0 0 10 0 0 0 0 0 0 0 0 0 0 0

Exochosphaeridium bifidum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 4 1

Fibrocysta spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0

Fibrocysta bipolaris 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 3

Glaphyrocysta spp. 0 9 0 0 0 0 0 0 0 0 19 6 4 0 0 0 0 0

Glaphyrocysta divaricata 0 0 0 0 0 0 0 0 0 0 14 2 7 0 0 0 0 0

Glaphyrocysta intricata 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0

Glaphyrocysta ordinata 0 0 0 0 0 0 0 0 0 0 30 1 0 0 0 0 0 0

Hafniasphaera spp. 0 0 0 0 0 0 0 6 0 0 0 4 2 2 8 0 8 31 Hafniasphaera delicata 0 0 0 0 0 1 7 4 3 0 6 0 5 7 0 0 0 0 Hafniasphaera hyalospinosa 0 0 0 0 0 0 1 0 15 0 0 0 0 0 0 0 0 0 Hafniasphaera septata 0 0 2 1 0 0 5 2 0 0 2 0 0 8 0 12 10 0 Homotryblium abbreviatum 0 0 0 0 1 0 1 0 0 5 0 0 0 0 0 0 0 0

Homotryblium plectilum 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0

Homotryblium tenuispinosum 0 30 0 0 2 1 3 0 0 5 0 0 0 0 0 0 0 0

Hystrichokolpoma rigaudiae 0 0 0 0 0 1 1 1 1 0 1 0 3 0 0 0 1 0

Hystrichosphaeridium tubiferum 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0

Ifecysta fusiforma 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 3 0 0

Ifecysta heterospinosa 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

Ifecysta lappacea 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6

Ifecysta pachyderma 0 0 0 0 0 0 0 0 0 0 0 0 0 7 0 1 0 0

Impagidinium spp. 0 0 0 0 0 0 0 2 0 0 0 0 2 0 1 0 4 0

Impagidinium aspinatum 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0

Impagidinium celineae 0 0 0 0 0 1 0 0 0 18 0 0 0 1 0 0 0 0

Impletosphaeridium spp. 0 0 0 0 0 1 7 2 6 196 0 26 11 29 5 0 0 0

Isabelidinium sp. 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Kallosphaeridium spp. 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0

Kallosphaeridium brevibarbatum 0 0 0 0 0 10 0 0 0 0 0 0 0 0 0 0 0 0

Kallosphaeridium orchiesense 0 0 0 0 0 0 15 1 0 1 0 1 2 0 0 0 0 0

Kallosphaeridium parvum 0 0 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0

Kallosphaeridium yorubaense 0 0 0 0 0 1 4 8 8 4 0 0 2 0 0 0 0 0

Lingulodinium bergmannii 0 0 0 0 0 0 0 0 0 0 0 1 3 0 0 0 0 0

Magallanesium densispinatum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0

Melitasphaeridium pseudorecurvatum 0 0 0 0 0 3 2 0 0 0 0 1 1 0 0 0 0 0

Minisphaeridium latirictum 0 0 0 0 0 1 1 5 0 0 0 0 0 0 0 0 0 0

Muratodinium fimbriatum 0 14 0 20 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Operculodinium spp. 6 13 4 4 0 10 33 20 9 4 1 47 21 3 11 62 19 68

Operculodinium bellulum 0 0 0 0 0 16 0 0 5 0 0 9 0 0 0 2 0 0

Operculodinium centrocarpum 16 21 0 9 1 13 28 19 25 1 1 15 1 3 0 1 16 22

Operculodinium exquisitum 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0

Operculodinium microtriainum 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 3 0 0

Operculodinium nanaconulum 0 0 0 0 0 2 0 0 0 0 0 0 1 0 0 0 0 0

Operculodinium nitidum 0 0 0 0 0 1 0 3 0 2 0 6 13 1 0 4 0 0

Operculodinium severinii 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0

Operculodinium tiara 0 0 0 0 0 0 4 3 0 4 0 20 2 0 0 6 3 16

Operculodinium uncinispinosum 0 0 0 0 0 0 0 0 0 0 0 0 4 0 0 11 0 0

Palaeocystodinium spp. 0 0 0 0 3 0 0 0 0 3 0 3 1 0 2 0 0 0

Palaeocystodinium golzowense 0 0 0 0 0 7 0 0 1 2 0 0 2 7 0 1 82 11

Palaeocystodinium cf.P.golzowense 0 0 0 0 0 7 0 0 0 0 0 0 0 0 0 0 0 0

Palaeocystodinium rafii 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0

Palaeocystodinium sp B. 0 0 0 0 0 2 0 0 0 1 0 0 0 2 0 0 2 1

Paucisphaeridium spp. 0 0 0 0 0 4 11 2 2 1 0 16 8 0 0 0 0 0

Pterodinium spp. 0 0 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0

Pterodinium aliferum 0 0 0 0 0 2 0 1 0 0 0 0 0 0 0 0 0 0

Pterodinium cingulatum 0 0 0 0 0 0 0 0 0 1 0 0 3 0 0 0 0 0

Phelodinium magnificum 0 0 0 0 0 0 0 0 0 0 0 0 2 3 0 0 0 0

Phelodinium pumilum 0 0 0 0 0 2 0 0 0 0 0 0 2 0 0 0 0 0

Polysphaeridium spp. 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Polysphaeridium biformum 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Polysphaeridium congregatum 0 0 0 0 0 2 0 0 4 0 9 0 0 0 0 0 0 0

Polysphaeridium subtile 0 0 0 18 0 1 4 0 5 0 3 0 0 0 0 0 0 0

Polysphaeridium zaharyi 0 0 0 0 0 4 0 0 22 0 6 0 0 0 0 0 0 0

Pyxidinopsis ardonensis 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 2 0 0

Senegalinium spp. 0 0 0 0 0 0 7 4 0 3 2 1 0 0 0 0 0 0

Spiniferella cornuta 0 0 0 0 0 1 0 0 0 1 2 0 0 0 5 43 7 10

Spiniferites spp. 9 11 174 66 0 140 86 108 87 16 18 34 114 33 15 72 78 53

Spiniferites mirabilis 0 0 0 10 0 0 0 0 0 0 1 2 0 11 0 2 0 0

Spiniferites perforatus 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0

Spiniferites pseudofurcatus 0 16 0 0 0 0 0 1 1 4 1 3 4 1 0 7 0 0

Spiniferites ramosus 277 26 175 44 0 25 17 64 53 37 10 15 40 21 0 8 4 26

Tanyosphaeridium xanthiopyxides 0 0 0 0 0 0 0 0 0 0 0 5 4 0 0 0 6 10

Tectatodinium pellitum 0 0 0 0 0 0 0 0 0 0 0 1 2 0 0 0 0 0

Tectatodinium nigeriaense sp. nov 0 0 0 0 0 0 0 0 2 0 0 0 0 172 3 6 36 24

Thalassiphora delicata 0 0 0 0 0 0 1 1 0 0 0 2 5 0 1 0 0 0

Thalassiphora sp. cf. T. patula 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0

Trichodinium hirsutum. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 20

Wilsonidium nigeriaense 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0

Unidentified cysts 0 0 0 0 0 0 7 18 0 0 0 0 0 0 3 39 0 1

Total Counted 310 228 365 224 30 357 328 297 316 401 178 442 407 332 310 333 303 331

APPENDIX B.

LIST OF DINOFLAGELLATE CYST TAXA

Achilleodinium bianii Hultberg, 1985c

Achomosphaera spp.

Achomosphaera alcicornu (Eisenack, 1954b) Davey and Williams, 1966a

Achomosphaera ramulifera (Deflandre, 1937b) Evitt, 1963

Adnatosphaeridium membraniphorum Jan du Chêne and Adediran, 1985

Adnatosphaeridium multispinosum Williams and Downie, 1966c

Adnatosphaeridium robustum (Morgenroth, 1966a) de Coninck, 1975

Adnatosphaeridium ivoriense sp. nov.

Amphorosphaeridium multispinosum (Davey and Williams, 1966b) Sarjeant, 1981

Andulasiella? sp.

Apectodinium spp.

Apteodinium spp.

Areoligera spp.

Areoligera coronata (Wetzel, 1933b) Lejeune-Carpentier, 1938a

Areoligera gippingensis Jolley, 1992

Areoligera medusettiformis Wetzel, 1933b

Areoligera senonensis Lejeune-Carpentier, 1938a

Areoligera cf. A. senonensis Lejeune-Carpentier, 1938a

Areoligera sentosa Eaton, 1976

Areoligera tauloma Eaton, 1976

Areoligera volata Drugg, 1967

Batiacasphaeras spp.

Cerodinium boloniense (Riegel, 1974) Lentin and Williams, 1989

Cerodinium diebelii (Alberti, 1959b) Lentin and Williams, 1987

Cleistosphaeridium spp.

Cordosphaeridium spp.

Cordosphaeridium exilimurum Davey and Williams, 1966b

Cordosphaeridium fibrospinosum Davey and Williams, 1966b

Cordosphaeridium gracile (Eisenack, 1954b) Davey and Williams, 1966b

Cyclonephelium spp.

Damassadinium californicum (Drugg, 1967) Fensome et al., 1993

Damassadinium heterospinosum (Matsuoka, 1983c) Fensome et al., 1993b

Dapsilidinium pastielsii (Davey and Williams, 1966b) Bujak et al., 1980

Deflandrea oebisfeldensis Alberti, 1959b

Diphyes spp.

Diphyes colligerum (Deflandre and Cookson, 1955) Cookson, 1965a

Diphyes digitum sp.nov.

Diphyes pseudoficusoides Bujak, 1994

Diphyes spinula (Drugg, 1970b) Stover and Evitt, 1978

Eocladopyxis peniculata Morgenroth, 1966a

Eocladopyxis furculum sp. nov.

Exochosphaeridium bifidum (Clarke and Verdier, 1967) Clarke et al., 1968

Fibrocysta spp.

Fibrocysta bipolaris (Cookson and Eisenack, 1965b) Stover and Evitt, 1978

Glaphyrocysta spp.

Glaphyrocysta divaricata (Williams and Downie, 1966c) Stover and Evitt, 1978

Glaphyrocysta intricata (Eaton, 1971) Stover and Evitt, 1978

Glaphyrocysta ordinata (Williams and Downie, 1966c) Stover and Evitt, 1978

Hafniasphaera spp.

Hafniasphaera delicata Fensome et al., 2009

Hafniasphaera hyalospinosa Hansen, 1977

Hafniasphaera septata (Cookson and Eisenack, 1967b) Hansen, 1977

Homotryblium abbreviatum Eaton, 1976

Homotryblium plectilum Drugg and Loeblich, 1967

Homotryblium tenuispinosum Davey and Williams, 1966b

Hystrichokolpoma rigaudiae Deflandre and Cookson, 1955

Hystrichosphaeridium tubiferum (Ehrenberg, 1838) Deflandre, 1937

Ifecysta fusiforma Antolinez and Oboh-Ikuenobe, 2007

Ifecysta heterospinosa Antolinez and Oboh-Ikuenobe, 2007

Ifecysta lappacea (Drugg, 1970) Antolinez and Oboh-Ikuenobe, 2007

Ifecysta Pachyderma Jan du Chêne and Adediran, 1985

Impagidinium spp.

Impagidinium aspinatum (Cookson and Eisenack, 1974) Damassa, 1979a

Impagidinium celineae Jan du Chêne, 1988

Impletosphaeridium spp.

Isabelidinium sp.

Kallosphaeridium spp.

Kallosphaeridium brevibarbatum de Coninck, 1969

Kallosphaeridium orchiesense de Coninck, 1975

Kallosphaeridium parvum Jan du Chêne, 1988

Kallosphaeridium yorubaense Jan du Chêne and Adediran, 1985

Lingulodinium bergmannii (Archangelsky, 1969a) Quattrocchio and Sarjeant, 2003

Magallanesium densispinatum (Stanley, 1965) Quattrocchio and Sarjeant, 2003

Melitasphaeridium pseudorecurvatum (Morgenroth, 1966a) Bujak et al., 1980

Minisphaeridium latirictum (Fensome et al., 2009) Davey and Williams, 1966b

Muratodinium fimbriatum (Cookson and Eisenack, 1967b) Drugg, 1970b.

Operculodinium spp.

Operculodinium bellulum Islam, 1983a

Operculodinium centrocarpum (Deflandre and Cookson, 1955) Wall, 1967

Operculodinium exquisitum Islam, 1983b

Operculodinium microtriainum (Klumpp, 1953) Islam, 1983a

Operculodinium nanaconulum Islam, 1983a

Operculodinium nitidum Islam, 1983a

Operculodinium severinii (Cookson and Cranwell, 1967) Islam, 1983b

Operculodinium tiara (Klumpp, 1953) Stover and Evitt, 1978

Operculodinium uncinispinosum (de Coninck, 1969) Islam, 1983b

Palaeocystodinium spp.

Palaeocystodinium golzowense Alberti, 1961

Palaeocystodinium cf. P. golzowense Alberti, 1961

Palaeocystodinium sp B Oboh-Ikuenobe et al., 1998

Palaeocystodinium rafii Antolinez and Oboh-Ikuenobe, 2007

Paucisphaeridium spp.

Phelodinium magnificum (Stanley, 1965) Stover and Evitt, 1978.

Phelodinium pumilum Liengjarern et al., 1980

Polysphaeridium spp.

Polysphaeridium biformum Islam, 1983b

Polysphaeridium congregatum (Stover, 1977) Bujak et al., 1980

Polysphaeridium subtile Davey and Williams, 1966b

Polysphaeridium zoharyi (Rossignol, 1962) Bujak et al., 1980

Pterodinium spp.

Pterodinium aliferum Eisenack, 1958a

Pterodinium cingulatum (Wetzel, 1933b) Below, 1981a.

Pyxidinopsis ardonensis Jan du Chêne, 1988

Sengalinium spp.

Spiniferella cornuta (Gerlach, 1961) Stover and Hardenbol, 1994

Spiniferites spp.

Spiniferites mirabilis (Rossignol, 1964) Sarjeant, 1970

Spiniferites perforatus (Davey and Williams, 1966a) Sarjeant, 1970

Spiniferites pseudofurcatus (Klumpp, 1953) Sarjeant, 1970

Spiniferites ramosus (Ehrenberg, 1838) Mantell, 1854

Tanyosphaeridium xanthiopyxides (Wetzel, 1933b ex Deflandre, 1937) Stover and Evitt,

1978

Tectatodinium pellitum Wall, 1967

Tectatodinium nigeriaense sp. nov.

Thalassiphora delicata Williams and Downie, 1966c

Thalassiphora sp. cf. T. patula (Williams and Downie, 1966c) Stover and Evitt, 1978

Trichodinium hirsutum Cookson, 1965b

Wilsonidium nigeriaense Jan du Chêne and Adediran, 1985

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a b a Francisca E. Oboh-Ikuenobe , Hernan Antolinez-Delgado , and Walaa K. Awad

aGeology and Geophysics Program, Department of Geosciences and Geological and

Petroleum Engineering, Missouri University of Science and Technology, 129 McNutt

Hall, Rolla, MO 65409-0410, USA bAmerisur Exploración Colombia, Ayasha Building Tv. 21 No. 98-71 6th Floor. Bogota

D.C., Colombia.

ABSTRACT

This study represents a contribution to the Late Paleocene-Early Eocene biostratigraphy in a low latitude stratigraphic setting where, published studies are few in comparison with mid- and high latitude regions. We generated data for 62 dinoflagellate cysts from a comprehensive analysis of 33 samples covering a 713-m interval in the Alo-1

Well in the northern Niger Delta (Anambra) Basin, Nigeria. Dinoflagellate cyst recovery in the samples varies from very good to poor, and the specimens are commonly well preserved. We calibrate the dinoflagellate cyst data with recent biozonation schemes for

ODP Hole 959D, Côte d’Ivoire-Ghana Transform Margin in the eastern Equatorial

Atlantic, which allowed for a valid comparison with published studies in well-dated rock sections in northwestern Europe, the Mediterranean region, New Zealand, and Tasmania.

Our observations show that there is better correlation between tropical and mid latitude dinoflagellate cyst assemblages compared to those in high latitude regions.

We use the last occurrence and/or last abundance events of dinoflagellate cysts to identify four biostratigraphic zones (zone E to zone H) in the Alo-1 Well.

Lithostratigraphic and biostratigraphic analyses suggest a late Selandian age for the contact between the Imo and Nsukka formations. Abundant thermophilic taxa that include the

Cordosphaeridium group and Apectodinuim dominate the assemblage recovered in the depositional succession. The late Selandian to early Thanetian sediments are dominated by the Cordosphaeridium group, and are succeeded by abundant to superabundant marker species of Apectodinium in the late Thanetian to Ypresian. The superabundance of

Apectodinium is significant because it is indicative of the global intense climatic warming that characterized the late Thanetian to early Ypresian. The Alo-1 Well dinoflagellate cyst data also suggest deposition under proximal, inner neritic conditions that preserved an assemblage dominated by species of Cordosphaeridium, Damassadinium, Ifecysta and

Polysphaeridium.

Key words: Alo-1 Well; Imo Formation; Nsukka Formation; Paleocene-Early Eocene; dinoflagellate cysts; Nigeria.

1. INTRODUCTION

The Early Paleogene represents a highly dynamic period in Earth’s history that was associated with globally elevated temperatures, significant evolutionary turnovers, and extinctions in the marine and terrestrial biota (Crouch, 2001; Zachos et al., 2008; Sluijs et al., 2006; McInerney and Wing, 2011). The sea surface temperatures (SST) of mid and high latitudes during the Paleocene-Eocene Thermal Maximum (PETM) were almost

74 equivalent to the modern tropical values (24-29°C), while the equatorial regions were extremely warm (>35°C; Frieling et al., 2017). The presence of warm-water pelagic marine organisms, as well as vegetation and soil types suggest that the high latitudes in both hemispheres were warm (Wing and Greenwood, 1993; Sluijs and Brinkhuis, 2009).

Palynology is an important branch of paleontological sciences that studies the organic microfossils preserved in sedimentary rocks such as pollen, spores, dinoflagellate cysts and acritarchs. Some of the important applications for this science are determining relative ages, reconstructing paleoenvironmental and paleoclimatic conditions, and identifying and correlating rock sequences. Palynological studies of the Early Paleogene in tropical regions are not as substantial as those from mid- to high latitudes. Lack of information on palynological studies from tropical regions is due to poorly preserved environmental settings (e.g., stratifiled lakes, good outcrop exposures) and the confidentiality associated with acquiring data from the petroleum companies exploring in the such regions, including the Niger Delta.

Tropical palynological studies have focused mainly on the analyses of pollen and spores (sporomorphs) for relative dating and reconstructing paleoenvironmental, paleogeography, paleoclimatology conditions, and floral evolution (e.g., Germeraad et al.

1968). In spite of the attributes noted above, pollen and spores are not commonly used for defining or constraining the standard geologic timescale for the Paleogene (Gradstein et al., 2012). The timescale is defined mainly by calcareous marine microfossils such as planktonic foraminifera and coccolithophorids. Organic-walled dinoflagellate cysts are preserved in nearshore sediments and they are incorporated into the more recent timescale

(Gradstein et al., 2012). Applications of dinoflagellate cysts have been successful in the

Paleogene biostratigraphic and paleoecologic studies of mostly mid and high latitudes (e.g.,

Crouch, 2001; Sluijs et al., 2005; Sluijs and Brinkhuis, 2009; Crouch et al., 2014) because they provide paleoecological information about relative variations in salinity, productivity

(nutrient enrichment), and relative sea-surface temperatures in coastal and neritic settings

(Dale et al., 2002) Furthermore, they are often preserved alongside spores and pollen, thereby providing a tool for correlating sediments from near-shore to slope depositional settings (Traverse, 2007).

It is clear that there is an apparent scientific research gap for further palynological study in tropical regions. Dinoflagellate cyst data offer the opportunity for biostratigraphic dating as well as the interpretation on the extraneous drivers controlling their distributions.

Therefore, the availability of ditch cutting samples from a nearly continuous succession in

Alo-1 Well in the northern Niger Delta (Anambra Basin), Southeast Nigeria provides the opportunity to study the following objectives: (1) to establish the biostratigraphic zonations in the well and calibrate them with the ODP Hole 959D; (2) to interpret the paleoenvironmental settings of the studied interval and relate the zonations to the depositional environment; and (3) to compare the dinoflagellate cyst composition with those from other low latitude regions and mid and high latitude areas.

2. GEOLOGIC SETTING

The Southern Nigeria sedimentary basin comprises the southern Benue Trough,

Niger Delta (which now includes the Anambra Basin; Nwajide, 2013), Benin Embayment,

Abakaliki Fold Belt, Afikpo Syncline, and the Calabar Flank (Fig. 1). The depositional and

76 tectonic histories of the basin are related to the tectonic stages and epeirogenic movements associated with the separation of the African and South American continents during the

Early Cretaceous (Murat, 1972; Burke, 1996).

2.1. TECTONICS

The tectonic and structural framework of the northern Niger Basin (Anambra

Basin) is controlled by a much larger and older tectonic feature, the Benue Trough (Late

Jurassic to Early Cretaceous), which is a northeast-southwest folded rift basin (Fig. 1) representing the failed arm of an aulacogen that runs diagonally across Nigeria. The Benue

Trough formed simultaneously with the opening of the Gulf of Guinea and the Equatorial

Atlantic in Aptian-Albian times, when the equatorial part of Africa and South America began to separate (Reijers et al., 1997). Taphrogenic subsidence along fundamental transform faults cut through the lithosphere and are the landward continuations of the Chain and Charcot oceanic fracture zones initiated the Benue Trough (Emery et al., 1975). These faults subsequently controlled the location of the main axis of subsidence of the resultant basins (Reijers et al., 1997). The Chain Fracture Zone coincides with the Benin Hinge Line of the western Benue Trough, whereas the eastern portion of the trough, which is referred to as the Calabar Flank (Reijers, 2011), is more complicated. The Calabar Flank comprises northwest-southeast tending structures known as the Ikang Trough, Ituk High, and Calabar

Hinge Line (Fig. 1). Sinistral transcurrent shearing along the fracture zones caused deformation in the Benue Trough and modified the Gulf of Guinea continental margin from the simple pull-apart basement structures with half-grabens underlying the West African

77 continental margins north and south of the Gulf of Guinea (Reijers et al., 1997; Reijers,

2011).

Murat (1972) proposed three tectonic phases in the stratigraphic evolution of the region during which the axis of the main basin shifted and gave rise to three successive basins. These three phases were: (1) the Abakaliki-Benue phase (Aptian-Santonian), (2) the Anambra-Benin phase (Campanian-mid Eocene), and (3) the southern Niger Delta phase (Late Eocene-Pliocene).

Phase 1 (Abakaliki-Benue) commenced during the middle Albian after major northeast-southwest movements caused the faulting that resulted in the rift-like Abakaliki-

Benue Trough. Shelf deposits were laid down on the Anambra Platform between the

Calabar and Benin hinge lines and the trough.

Fig. 1. Map of Southern Nigeria showing the location of Alo-1 Well in the Anambra Basin and megatectonic frame of southern Nigeria sedimentary basin (modified from Reijers et al., 1997). Inset shows the location of Nigeria in West Africa.

Phase 2 (Anambra-Benin) was characterized by compressional movements along the established northeast-southwest trend, which resulted in the folding and uplifting of the

Abakaliki-Benue Trough during the late Santonian to early Campanian, and in the formation of the Anambra Basin. The adjoining Benin Flank basement underwent a transgression that lasted until the Early Eocene.

Phase 3 (southern Niger Delta) was initiated by a regression during the Middle and

Late Eocene. Vertical movements of blocks bounded by northeast-southwest and northwest-southeast trending faults resulted in the deposition of a large deltaic complex in the down-dip Anambra Basin. This, however, preceded the subsidence of the Oligocene to

Recent Niger Delta Basin along the northwest-southeast fault trend.

2.2. STRATIGRAPHY AND SEDIMENTOLOGY

The Paleogene time in southeastern Nigeria is represented by a sedimentary succession that is thicker than 3,500 m (Fig. 2). These deposits are divided into the Nsukka

Formation (~350 m), Imo Formation (~1,000 m), Ameki Group (~1,900 m), and Ogwashi-

Asaba Formation (~250 m) (Oboh-Ikuenobe et al., 2005). The Imo, Ameki and Ogwashi-

Asaba, which were previously considered outcrop equivalents of the subsurface units of the Niger Delta, have now been formally assigned to the Niger Delta territory (Nwajide,

2013).

The Nsukka Formation overlies the Ajali Sandstone. The lowermost part of the

Nsukka Formation comprises coarse to medium grained sandstones, which change upward into well-bedded blue clays, fine-grained sandstones, and carbonaceous shales with thin bands of limestone (Oboh-Ikuenobe et al., 2005). According to Obi et al. (2001), deposition

79 of the Nsukka Formation represented a phase of fluvio-deltaic sequence that evolved close to the end of the Maastrichtian and continued during the Paleocene.

Fig. 2. Summary of stratigraphic data of the Paleogene succession in southeastern Nigeria (from Oboh-Ikuenobe et al., 2005).

The Imo Formation consists of blue-gray clays and shales and black shales with bands of calcareous sandstone, marl and limestone. The sediments reflect shallow-marine shelf conditions in which foreshore and shoreface sands formed occasionally (Nwajide,

2013). The shales contain a significant amount of organic matter and are potential source

80 rocks for hydrocarbons in the eastern part of the Niger Delta and in the Anambra Basin

(Reijers et al., 1997).

The Ameki Group is represented by an alternation of sands, silts, and clays in various proportions and thicknesses. These sediments have been interpreted as continental, prodeltaic, estuarine, lagoonal and open marine based on the successive faunal contents

(Reijers et al., 1997; Nwajide, 2013).

The Ogwashi-Asaba Formation comprises alternating coarse-grained sandstones, lignite seams, and light colored clays of continental origin. It was deposited in alluvial or upper coastal plains environments following a southward shift of deltaic deposition advancing into a new depocenter (Reijer, 2011).

3. PREVIOUS BIOSTRATIGRAPHIC STUDIES

The Early Paleogene calcareous microfossil biostratigraphy of southeastern Nigeria has been studied by Berggren (1960) and Adegoke (1969). Relevant macrofossil

(vertebrate and invertebrate) biostratigraphic and paleoenvironmental studies include those by Adegoke et al. (1981), and Arua (1982). Furthermore, some palynological studies were carried out on southeastern Nigeria to establish the age of the sediments and reconstruct the paleoenvironment (e.g., Germeraad et al., 1968; Oboh-Ikuenobe et al., 2005).

Previous studies of tropical Paleogene dinoflagellate cysts have documented well- preserved and diverse dinoflagellate cyst assemblages, especially in West Africa (Jan du

Chêne and Adediran, 1985; Willumsen et al., 2004; Antolinez and Oboh-Ikuenobe, 2007).

Most of these studies focused mainly on taxonomy and did not provide information about

81 the stratigraphic distribution and/or the paleoenvironmental significance of the assemblages. Nevertheless, they provided insights into the general composition of tropical dinoflagellate cyst assemblages during the Early Paleogene. Willumsen et al. (2004) studied the changes in the dinoflagellate cyst composition during the Maastrichitian-Early

Paleocene interval in the Alo-1 Well and noticed changes from nearshore taxa

(Cordosphaeridium spp. and Ifecysta spp.) at the bottom of the interval to more offshore taxa (Spiniferites spp. and Impagidinium spp.) at the top, Willumsen (2003, unpublished report) concluded that the environment deepened upward. Recently, Awad and Oboh-

Ikuenobe (2016) provided paleoenvironmental interpretation and biostratigraphic zonations for the Paleocene-Eocene interval in ODP Hole 959D in the Côte d’Ivoire-Ghana

Transform Margin. They proposed five zones for the studied interval; four of the proposed five zones (zone 1- zone 4) were Paleocene in age, while zone 5 was assigned to the Early

Eocene.

In Alo-1 Well, analyses of terrestrial and marine palynomorphs provide the main biostratigraphic control for the stratigraphic section. In a preliminary unpublished biostratigraphic study, Shell Petroleum Development Company of Nigeria identified the tops of two pollen zones, P200 and P100, at 274 m and 622 m, respectively (Shell

Petroleum, 1976). According to Evamy et al. (1978), zone P200 is Late Paleocene in age, while zone P100 is Early Paleocene. No additional palynomorph zones were identified in that study (Fig. 3).

Willumsen (2003) and Willumsen et al. (2004) identified four informal dinoflagellate cyst zones (A to D) in the 878 m to 1694 m interval of Alo-1 Well (Fig. 3).

Zones A to C (1097-1694 m) were assigned Lower, Upper and uppermost Maastrichtian

82 age based on the presence of stratigraphically important taxa, such as Andalusiella cf. A. mauthei, Palaeocystodinium australinum, Senegalinium bicavatum, and

Tanyosphaeridium xanthiopyxides. The first occurrence of some important index fossils, including Hafniasphaera septate, Kallosphaeridium nigeriense, Kallosphaeridium yorubaense, Palynodinium grallator, and Senoniasphaera inornata, was used to assign a

Lower Paleocene (Danian) age to Zone D (878 to 1097 m). The samples analyzed in the present study were collected from above the interval studied by Willumsen (2003) and

Willumsen et al. (2004).

4. MATERIALS AND METHODS

Palynological samples used for this study were derived from ditch cutting samples from the Alo-1 Well drilled in 1976 by Shell Petroleum Development Company of Nigeria

40 kilometers north of Onitsha in the Anambra Basin, southeastern Nigeria (confidential company location). Thirty-three samples from the Paleocene interval in Alo-1 Well, were analyzed for their dinoflagellate cyst contents (Fig. 3; Table 1). The sandstone and transitional muddy sandstone in the upper part of Nsukka Formation and mudstones in the lower part of Imo Formation were the focus of this study.

Palynological laboratory techniques were performed on the studied samples

(Traverse, 2007) to extract the organic fraction. This included treatment with using HCL and HF to remove carbonate and siliceous components, respectively. The organic residues were oxidized using Schultze solution (KClO3 plus HNO3) and screened through 10 μm sieves.

Three hundred dinoflagellate cyst specimens were counted per slide, except for those samples with low recovery. Additionally, 300 sporomorphs vs. dinoflagellate cysts were counted in order to record variations in the proportion of terrestrial and marine components related to changes in the depositional site and extraneous drivers. We identify sixty-two dinoflagellate cyst taxa in Alo-1 Well (Appendix A). Recovery and preservation were variable in the samples, perhaps due to processing proceedures at two separate laboratories: abundant (generally >150) and well-preserved specimens in samples with the prefix R (Table 1) vs. few (<40) and poorly preserved specimens in samples with the prefix

Quantitative analysis was conducted only on samples with more than 100 dinoflagellate cyst specimens and discussed as follow: rare (<1-5 %), common (6-10 %), frequent (11-20 %), abundant (21-40 %) and superabundant (>40%). A Nikon transmitted light microscope with interference contrast was used in the identification and description of the recorded specimens. All the materials are housed in the palynological repository located in the Paleontology Laboratory at Missouri University Science and Technology,

USA. Figures 4-7 contain details of the illustrated specimens, which include the sample number, and England Finder (EF) reference.

Table 1. List of Alo-1 Well samples and their corresponding Missouri University of Science and Technology repository numbers and depths.

Samples Antolinez and Oboh- Repository No. Depth (m) Ikuenobe (2007)* AL1 R-1134-2 MST-1437-S1 54.9 AL2 B-11286 MST-1439-S1 73.0 AL3 B-11287 MST-1440-S1 91.4 AL4 R-1134-3 MST-1441-S1 109.7 AL5 B-11288 MST-1442-S1 146.3 AL6 R-1134-4 MST-1443-S1 164.6 AL7 B-11289 MST-1444-S1 182.9 AL8 B-11290 MST-1445-S1 201.0 AL9 R-1134-5 MST-1446-S1 219.4 AL10 B-11291 MST-1447-S1 237.7 AL11 B-11292 MST-1448-S1 256.0 AL12 R-1134-6 MST-1449-S1 274.3 AL13 B-11293 MST-1450-S1 292.6 AL14 R-1134-7 MST-1451-S1 329.2 AL15 B-11294 MST-1452-S1 365.8 AL16 R-1134-8 MST-1453-S1 384.0 AL17 B-11295 MST-1454-K2 402.3 AL18 R-1134-9 MST-1455-S1 438.9 AL19 B-12270 MST-1456-S1 457.2 AL20 B-12271 MST-1457-S1 475.5 AL21 R-1134-10 MST-1458-S1 493.7 AL22 B-12272 MST-1459-S1 530.3 AL23 R-1134-11 MST-1460-S1 548.6 AL24 B-12273 MST-1461-S1 566.9 AL25 B-12274 MST-1461-K1 585.2 AL26 R-1134-12 MST-1462-S1 603.5 AL27 B-12275 MST-1463-S1 621.8 AL28 R-1134-13 MST-1464-S1 658.4 AL29 B-12276 MST-1465-S1 676.6 AL30 B-12277 MST-1465-S2 695.0 AL31 R-1134-14 MST-1466-S1 713.2 AL32 B-12278 MST-1467-S1 731.5 AL33 R-1134-15 MST-1468-S1 768.1 * The prefixes R- and B- denote two separate batches of processed samples

Fig. 3. Lithology, inferred stratigraphy and sample horizons in the interval studied. The sand percentage profile was derived from sand vs. shale data provided by Shell Petroleum (1976).

5. RESULTS AND DISCUSSION

5.1. STRATIGRAPHIC DISTRIBUTION OF DINOFLAGELLATE CYSTS

The stratigraphic distributions of selected dinoflagellate cyst taxa are shown in

Figure 8. The lower portion of the section, below 470 m, is characterized by the occurrence of Areoligera gippingensis (Fig. 4I), Diphyes bifidum (Fig. 5E), Spinidinium densispinatum

(Fig. 6L) and abundant to superabundant intervals of Ifecysta spp. (Figs. 6A-6D). The LOs

(last occurrences) of Areoligera gippingensis, Spinidinium densispinatum and spot occurrence of Impagidinium celineae (Fig. 6E) are recorded in sample AL21 (493.7 m), followed by the LO of Cerodinium glabrum (Fig. 4L) in sample AL20 (475.5 m).

Damassadinium heterospinosum (Fig. 5C), Ifecysta lappacea (Fig. 6C),

Palaeocystodinium rafii (Fig. 7C) and Phelodinium magnificum (Fig. 7D) all have their

LOs toward the middle to upper middle part of the section in samples AL14 (329.2 m),

AL9 (219.4 m), AL18 (438.9 m), AL6 (164.6 m), respectively. Furthermore, abundance to superabundance of Apectodinium spp. (Figs. 4D-4F), Ifecysta pachyderma (Fig. 6D) and

Impletosphaeridium spp. (Figs. 6G-6H) are observed in this part of the section.

The LOs of Hafniasphaera hyalospinosa (Fig. 5J), Ifecysta pachyderma,

Oligokolpoma sp. A. (Figs. 6M-6N, a detail description in Appendix C) Thalassiphora delicata (Fig. 7I) and Wilsonidium stellatum (Fig. 7J) occur in sample AL4 (109.7 m). This same sample records spot occurrences of Damassadinium sp. cf. D. impages (Fig. 5D) and

Impagidinium aspinatum (Fig. 6F). The upper portion of Alo-1 Well from samples AL1 to

AL9 (~ 50 to 218 m) is characterized by common to frequent abundance of

Adnatosphaeridium spp. (Figs. 4B-4C), and abundance to superabundance of

Polysphaeridium spp., (Figs. 7E-7F) in addition to the presence of the following taxa:

Areosphaeridium diktyoplokum (Fig. 4J), Glaphyrocysta ordinata (Fig. 5I), Ifecysta? sp.

A. (Figs. 5K-5L; see a detailed description in Appendix C), and Muratodinium fimbriatum.

The following taxa range from the lower to upper portions of the section: Apectodinium spp., Cerodinium boloniense (Fig. 4K), Glaphyrocysta divaricata (Fig. 5H),

Hystrichosphaeridium tubiferum, Ifecysta fusiforma (Fig. 6A), Impletosphaeridium spp., and Palaeocystodinium golzowense (Figs. 7A-7B).

Fig. 4. Photomicrographs no 1 of dinoflagellate cysts. A. Achomosphaera quadrata. Right lateral view, high focus, AL4, EF T19/1. B. Adnatosphaeridium membraniphorum. Uncertain view, mid focus, AL16, EF Q40. C. Adnatosphaeridium multispinosum. Antapical view, mid focus, AL4, EF L22. D-F. Apectodinium spp., D. Apectodinium homomorphum. Uncertain view, high focus, AL16, EF N32/1. E. Apectodinium Hyperacanthum. Left lateral view, high focus, AL4, EF S20/2. F. Apectodinium quinquelatum. Left lateral view, high focus, AL4, EF J18/1. G-H. Apteodinium spp., G. Dorsal view, high focus, AL4, EF J23/4. H. Oblique lateral view, high focus, AL21, EF K12/4. I. Areoligera gippingensis. Ventral view, high focus, AL21, EF K38/4. J. Areosphaeridium diktyoplokum. Uncertain view, high focus, AL1, EF R31. K. Cerodinium boloniense. Ventral view, low focus, AL2, EF R46/3. L. Cerodinium glabrum. Dorsal view, low focus, AL26, EF Q15.

Fig. 5. Photomicrographs no 2 of dinoflagellate cysts. A. Cordosphaeridium delimurum. Right lateral view, mid focus, AL4, EF H36/1. B. Cordosphaeridium fibrospinosum. Ventral view, high focus, AL4, EF K32/4. C. Damassadinium heterospinosum. Antapical view, mid focus, AL14, EF T43/2. D. Damassadinium sp. cf. D. impages. Oblique dorsal view, high focus, AL4, EF J22/2. E. Diphyes bifidum. Uncertain view, mid focus, AL26, EF H35/1. F. Diphyes colligerum. Dorsal view, mid focus, AL6, EF M39. G. Eocladopyxis peniculata. Uncertain view, mid focus, AL9, EF S34/4. H. Glaphyrocysta divaricata. Dorsal view, high focus, AL4, EF V41. I. Glaphyrocysta ordinata. Dorsal view, mid focus, AL1, EF U27. J. Hafniasphaera hyalospinosa. Right lateral view, mid focus, AL4, EF G42. K-L. Ifecysta? sp. A., K. Dorsal view, mid focus, AL4, EF D43/1. L. Ventral view, mid focus, AL4, EF L36/3.

Fig. 6. Photomicrographs no 3 of dinoflagellate cysts. A-D. Ifecysta spp., A. Ifecysta fusiforma. Dorsal view, high focus, AL16, EF S40-3. B. Ifecysta heterospinosa. Oblique dorsal view, mid focus, AL26, EF Q23. C. Ifecysta lappacea. Left lateral view, high focus, AL26, EF W26-1. D. Ifecysta pachyderma. Left lateral view, high focus, AL31, EF T25-1. E. Impagidinium celineae. Oblique lateral view, high focus, AL21, EF N30. F. Impagidinium aspinatum. Right lateral view, mid focus, AL4, EF N20/3. G-H. Impletosphaeridium spp. Uncertain views, low focus, AL14, EF V30 (G), EF S39/1 (H). I. Kallosphaeridium orchiesense. Ventral view, high focus, AL6, EF L17. J. Lanternosphaeridium lanosum. Ventral view, high focus, AL9, EF R42. K. Lanternosphaeridium sp. 1. Oblique lateral view, low focus, AL14, EF H22. L. Spinidinium densispinatum. Ventral view, high focus, AL21, EF R24. M-N. Oligkolpoma sp. A., M. Lateral view, mid focus, AL16, EF L39/1. N. Dorsal view, mid focus, AL16, EF W32/4. O. Operculodinium tiara. Ventral view, mid focus, AL18, EF S44.

Fig. 7. Photomicrographs no 4 of dinoflagellate cysts. A-B. Palaeocystodinium golzowense. Left lateral views, mid focus, AL1, EF W8/2 (A), EF O43/1 (B). C. Palaeocystodinium rafii. Oblique lateral view, high focus, AL18, EF Q29. D. Phelodinium magnificum. Ventral view, high focus, AL21, EF R24/3. E-F. Polysphaeridium spp. Uncertain views, mid focus, AL1, EF W8/2 (E), EF O26 (F). G-H. Spiniferites spp., G. Spiniferites mirabilis. Right lateral view, mid focus, AL31, EF G40. H. Spiniferites sp. Ventral view, high focus, AL16, EF T39/2. I. Thalassiphora delicata. Left lateral view, high focus, AL4, EF S42. J. Wilsonidium stellatum. Dorsal view, low focus, AL8, EF W16/3.

Fig. 8. Biostratigraphic ranges of selected dinoflagellate cysts. Shown to the right of the figure are dinoflagellate cyst zones and nanoplankton zones of ODP Hole 959D (Shafik et al., 1998; Awad and Oboh-Ikuenobe, 2016), and the pollen zone P200 proposed by Shell Petroleum (1976; Late Paleocene according to Evamy et al., 1978).

5.2. DINOFLAGELLATE CYST ZONATIONS

We propose four dinoflagellate cyst zones (zone E to zone H) in the Paleocene-

Early Eocene interval of Alo-1 Well based on last occurrence or last abundance events of one or more taxa. The zones are named E to H because they overlie zone A to zone D (early

Maastrichtian-Early Paleocene) of Willumsen (2003) and Willumsen et al. (2004) for the same well. The use of first occurrence or abundance events has been avoided because all the Alo-1 Well samples are ditch cuttings that may have been contaminated by caving.

Given that there was no relative dating by other microfossils in the well, the zones in this study are calibrated with ODP Hole 959D in Côte d’Ivoire-Ghana Transform Margin

(Awad and Oboh-Ikuenobe, 2016). These authors proposed five dinoflagellate cyst zones for the Paleocene-Early Eocene and calibrated their zones with calcareous nannoplankton

(Shafik et al., 1998). Biostratigraphic summaries are presented in Figure 9. The four zones are described up-section below.

5.2.1. Zone E. The top of the zone is defined by the LOs of Areoligera gippingensis and Spinidinium densispinatum (Fig. 8), and the base of the zone is not defined in this study, but it may be equivalent to the upper boundary of zone 1 of Awad and Oboh-Ikuenobe

(2016). Typical dinoflagellate cysts include Cerodinium glabrum, Diphyes bifidum and

Impagidinium celineae occurring with high numbers of species of the Cordosphaeridium group (Ifecysta spp.). The age of this zone is Late Paleocene (late Selandian) and it is 274.4 m thick in the studied interval from sample AL33 (768.1 m) to sample AL21 (493.7 m).

Zone E is mainly equivalent to zone 2 in ODP Hole 959D (Awad and Oboh-Ikuenobe,

2016).

C. glabrum and I. celineae have previously been described from the Late Paleocene

(Gocht, 1969; Williams, 2006; Awad and Oboh-Ikuenobe,2016). The LO of A. gippingensis has been recorded at the Selandian-Thanetian boundary in Côte d’Ivoire-

Ghana Transform Margin, where it was used to delineate the top of zone 2 in ODP Hole

959D (Awad and Oboh-Ikuenobe, 2016). Furthermore, the LO of A. gippingensis has been assigned to an interval ranging the Selandian-Thanetian boundary in previous studies

(Williams et al., 1999; Williams, 2006). S. densispinatum was recorded in a narrow interval spanning the Danian-Selandian boundary by Thomsen and Heilmann-Clausen (1984), and in the basal part of the Selandian at several localities in the northern hemisphere (De

Coninck, 1975; Hansen, 1980). Furthermore, the LO of S. densispinatum has been observed in the late Selandian of the scotian margin, offshore eastern Canada (Fensome et al., 2009).

5.2.2. Zone F. The base of the zone is defined by the LOs of Areoligera gippingensis and Spinidinium densispinatum, and the top is defined by superabundance of

Apectodinium spp. (Fig. 8). Abundant to superabundant occurrence of Ifecysta spp. and

Impletosphaeridium spp. is followed by the superabundance of Apectodinium toward the upper part of the zone. The age of the zone is Late Paleocene (Thanetian) and it is 274.3 m thick from sample AL21 (493.7 m) to sample AL9 (219.4 m). This zone is mainly equivalent to zones 3 and 4 and the lower part of zone 5 in ODP Hole 959D (Awad and

Oboh-Ikuenobe, 2016). The base of the zone is correlated with the upper boundary of zone

2, while the top of the zone falls in zone 5 (Figs 8 and 9). The middle of the zone is roughly equivalent to the boundary between zones 3 and 4, based on the first common to frequent occurrence of Apectodinium.

The LO of C. glabrum is observed directly after the LO of A. gippingensis in Alo-

1 Well, suggesting an early Thanetian age for the lower part of zone F, as has been recorded in previous studies (Gocht, 1969; Heilmann-Clausen, 1985; Williams, 2006). The LO of C. glabrum is observed directly after the LO of A. gippingensis in Alo-1 Well, suggesting an early Thanetian age for the lower part of zone F, as has been recorded in previous studies

(Gocht, 1969; Heilmann-Clausen, 1985; Williams, 2006). An interval of abundant

Impletosphaeridium spp. occurring below the assemblages dominated by Apectodinium was reported by Awad and Oboh-Ikuenobe (2016) in Upper Paleocene sediments of Côte d’Ivoire-Ghana Transform Margin. The presence of Apectodinium spp. is a global event that indicates paleoclimate warming during the late Thanetian to early Ypresian (Prasad et al., 2006; Sluijs and Brinkhuis, 2009; Slimani et al., 2016).

The FO of Apectodinium has been recorded close to the Danian-Selandian boundary in the El Kef section, Tunisia (Brinkhuis et al., 1994; Guasti et al., 2005, 2006), which is considered the earliest occurrence of the genus. However, Apectodinium has been observed in many other studies in high, mid and low latitude regions in the Thanetian (e.g., Crouch et al., 2014; Slimani et al., 2016). In Alo-1 Well, Apectodinium spp. has its FO at the

Selandian-Thanetian boundary at sample AL21 (493.7 m), which is equivalent to the common occurrence of this genus. Furthermore, the FO of Apectodinium close to the

Selandian-Thanetian boundary in ODP Hole 959D (Awad and Oboh-Ikuenobe, 2016), indicates similar biostratigraphic events in the two sections.

The abundance to superabundance of Apectodinium throughout this zone suggests a Thanetian time for this part of the interval, which has been recorded in other low latitude regions and also in mid and high latitudes areas (Sluijs et al., 2011; Crouch et al., 2014).

Two abundant intervals (20-40 %) and a superabundant interval (>40%) of

Apectodinium are recorded in Alo-1 Well (see Fig. 8). They are as follows: 29% in sample

AL12 (274.3 m, zone F); 73.4% in sample AL9 (219.4 m, zone F); and 29.5% in sample

AL8 (201 m, zone G). Other studies from different latitudinal regions (Powell, 1992;

Prasad et al., 2006; Crouch et al., 2001, 2003a, 2003b; Slimani et al., 2016) noted the superabundance of Apectodinium during the Paleocene-Eocene Themal Maximum. In Alo-

1 Well, the Paleocene-Eocene boundary (?) is placed at the top of zone F, where

Apectodinium was most abundant.

The appearance of some Ypresian species (e.g., Muratodinium fimbriatum) in samples AL8 to AL1 suggests the boundary’s placement in this study. Awad and Oboh-

Ikuenobe (2016) did not record any superabundance of Apectodinium during the late

Thanetian. This discrepancy could be due to differences in the depositional environment, hydrographic current, incomplete sequences, and sampling gaps.

5.2.3. Zone G. The base of the zone is defined by superabundance of Apectodinium spp., while the top of the zone is defined by the LOs of Hafniasphaera hyalospinosa and

Thalassiphora delicata (Fig. 8). Typical of this zone is the FO of Wilsonidium stellatum and abundant occurrence of Apectodinium spp. In addition, the presence of H. hyalospinosa,

Kallosphaeridium spp., Polysphaeridium spp., and T. delicata is observed. The age of this zone is Early Eocene (Ypresian) and it is 109.7 m thick from sample AL9 (219.4 m) to sample AL4 (109.7 m). Zone G in Alo-1 Well is mostly equivalent to the lower part of zone 5 of Awad and Oboh-Ikuenobe (2016).

The assignment of a Ypresian age to the interval above 200 m in this study is in close agreement with the age Antolinez-Delgado (2004) proposed for the same interval, who assigned the interval above ~160 m to the earliest Eocene. The FO of M. fimbriatum has been reported in the Late Paleocene-Early Eocene in Nigeria (Jan du Chêne and

Adediran, 1985) and the Early Eocene of Côte d’Ivoire-Ghana Transform Margin (Awad and Oboh-Ikuenobe, 2016). The FO of W. stellatum in sample AL8 may indicate a Late

Paleocne-Early Eocene for the lower part of this zone. Wilsonidium is a member of the

Wetzelielloideae subfamily, which also includes Rhombodinium and Wetzeliella.

Representatives of this subfamily characterize mostly the Early Eocene in higher latitudes

(Bujak and Brinkhuis, 1998). However, studies in Kazakhstan (Iakovleva et al., 2001),

Uzbekistan (Crouch et al., 2003a), France and northern Kazakhtan (Iakovleva, 2016), Côte d’Ivoire-Ghana Transform Margin (Awad and Oboh-Ikuenobe, 2016) recorded the occurrence of species of Wilsonidium and Rhombodinium during the Late Paleocene.

The LO of T. delicata recorded at the top of this zone is significantly older than that in northwest Europe (Middle Eocene, 39 Ma), but it may be Early Eocene (its LO in the Southern hemisphere is Early Eocene, 52 Ma; Williams et al., 2004). Also, the LO of

H. hyalospinosa is much younger than that recorded in Denmark (late Danian, Hansen,

1977, 1979; Williams and Bujak, 1985). The occurrence of the FO of A. diktyoplokum

(Early Eocene in Northern hemisphere, 50.5 Ma) and the LO of T. delicata (Early Eocene in Southern hemisphere, 52 Ma) at the upper boundary of this zone is definetly different from their previous recordings at high latitudes (Williams et al., 2004). Their occurrence close to the Paleocene-Eocene boundary in Alo-1 Well may indicate a multi-million-year hiatus at Alo-1 between the inferred boundary and 50.5 Ma. Such hiatuses are generally common in shallow settings due to fairly high-amplitude sea level fluctuations in the early

Eocene (Sluijs et al., 2008). Another option may be that the equatorial FO of A. diktyoplokum in Alo-1 Well is much earlier than in high-latitudes and equivalent to the LO of T. delicata, which suggests strongly diachronous events between latitudes.

Mostly abundant occurrence of Apectodinium (20-30%) is recorded during this zone. Continuous abundance (29.5%) in sample AL8 and consistent occurrence (6-20%) of this genus in samples AL6 to AL4 support the early Ypresian similar to what have been observed in other low latitude regions and mid and high areas (Crouch et al.,2014; Mbesse

98 et al., 2012; Slimani et al., 2016). The continuous recording of Apectodinium spp. until the last sample of Alo-1 Well, its noticeable increase in abundance during this zone vs. early

LO of Apectodinium spp. in zone 4 of Awad and Oboh-Ikuenobe (2016), and the absence of a remarkable superabundance of the genus in zone 4 or 5 suggest differences in depositional systems or sampling problems.

5.2.4. Zone H. The base of the zone is defined by the LOs of Hafniasphaera hyalospinosa and Thalassiphora delicata (Fig. 8); however, the top of the zone is not defined in this study. Typical dinoflagellate cysts in this zone are Apectodinium spp.,

Adnatosphaeridium spp., Muratodinium fimbriatum and Polysphaeridium spp.

Areosphaeridium diktyoplokum and Ifecysta? sp. A. are restricted to the upper part of this zone. The age of this zone is Early Eocene (Ypresian) and it is 54.8 m thick from sample

AL4 (109.7 m) to sample AL1 (54.9 m). Zone H in Alo-1 Well is mostly equivalent to the upper part of zone 5 of Awad and Oboh-Ikuenobe (2016).

An interval of abundant Adnatosphaeridium spp. in Alo-1 Well is similar to what

Awad and Oboh-Ikuenobe (2016) recorded in the Early Eocene of ODP Hole 959D.

Harland (1979) indicated that most species of Apectodinium in northwest Europe were restricted to nannofossil zones CP8-CP9 (Late Paleocene-Early Eocene). While the LO of

Apectodinium has been generally recorded in lower Eocene sediments at many low and high latitude localities, its presence at the top of the study interval in the Alo-1 Well may support the lower Eocene assignment by Shell Petroleum (1976) due to the presence of some Ypresian species, such as Muratodinium fimbriatum and Areosphaeridium diktyoplokum (Jan du Chêne and Adediran, 1985; Stover and Williams, 1995; Williams et al., 2004; Awad and Oboh-Ikuenobe, 2016).

5.3. QUANTITATIVE CHANGES IN THE DINOFLAGELLATE CYST DISTRIBUTION

Palynomorph recovery in Alo-1 Well varies from poor to excellent with good preservation of specimens in most intervals. Sporomorphs (pollen and spores) represent between 30% and 50% of the palynomorph counts in Alo-1 Well; however, they are up to

67% in some samples. There is a general decrease in terrestrial palynomorphs from the bottom to the top of the well (Fig. 10). Some taxa and/or groups of morphologically related taxa typically represent 80-90% of the dinoflagellate cyst assemblage. Their quantitative distribution (only in samples with >100 dinoflagellate cyst specimens) is shown in Figure

10. The morphological groups are: (1) Adnatosphaeridium spp. (mainly A. multispinosum);

(2) Cordosphaeridium group (which includes Cordosphaeridium spp., Ifecysta spp.,

Damassadinium spp. and Lanternosphaeridium spp.); (3) Polysphaeridium group

(Polysphaeridium spp., and Eocladopyxis spp.); (4) Spiniferites group (Spiniferites spp.,

Achomosphaera spp. and Hafniasphaera spp.); (5) Apectodinium spp.; (6) Glaphyrocysta group (Glaphyrocysta spp. and Areoligera spp.); (7) Operculodinium spp.; and (8)

Impletosphaeridium spp. The Cordosphaeridium group (mainly Ifecysta spp.) dominates the entire studied section, mostly comprising 35-75 % of the assemblage. The studied interval is interpreted as follows: Late Paleocene (Late Selandian), Late Paleocene

(Thanetian) and Early Eocene (Ypresian) (Fig. 10).

5.3.1. Late Paleocene (Late Selandian, 768.1-493.7 m). This interval is dominated by the Cordosphaeridium group, which constitutes almost 30-70 % of the assemblage (Fig. 10). Representatives of this group, mainly Ifecysta spp., exhibit wide variations in the development of apical and antapical protrusions, and the morphology of processes especially in this part of the section. Other constituents of the Selandian

100 assemblage are Spiniferites (15-45 %), Operculodinium (<20%), Glaphyrocysta group

(mainly Areoligera gippingensis, <10%), and Impletosphaeridium spp. (<10%).

Both Spiniferites and Operculodinium spp. have a widespread distribution in the modern ocean; therefore, they have been recorded from many environment settings, such as oceanic to restricted marine environments (Wall et al., 1977; Brinkhuis, 1994). However, they can give an important interpretation for the paleoenvironment when relating them to others dinoflagellate cyst assemblages. The spot occurrence of Impagidinium celineae in sample AL21 (Fig. 8) suggests an oceanic influence on this part of the section (Wall et al.,

1977; Edwards and Andrle, 1992; Udeze and Oboh-Ikuenobe, 2005).

Common to frequent occurrence of the Glaphyrocysta group (mainly Areoligera gippingensis) in sample AL21 indicates a high energy environment with the possibility of a transgression event (Sluijs and Brinkhuis, 2009). The high terrestrial inputs (50-70%) in the lower part of Alo-1 (Fig. 10) with the occurrence of the Glaphyrocysta group indicates an inner neritic environment for this part of the interval (Wall et al., 1977; Iakovleva, 2011).

Apectodinium spp. appear for the first time in the section (< 5% in sample AL21, 493.7 m) at the late Selandian-early Thanetian boundary.

5.3.2. Late Paleocene (Thanetian, 438.9-219.4 m). The Cordosphaeridium group is still superabundant (40-75%), followed by Apectodinium spp. (5-73.4 %). The first abundance of Apectodinium (29%) is recorded in sample AL12 (274.3 m) followed by superabundance in sample AL9 (219.4 m), both in the Late Paleocene (Thanetian).

Specimens of this genus indicate the onset of global paleoclimatic (warming) and paleoenvironmental changes during the Late Paleocene (Sluijs et al., 2007a, 2007b). Some factors control the abundance of Apectodinium, such as the temperature (warm climate),

101 environment (more common in nearshore), lower salinity waters, and strong nutrient availability (Guasti et al., 2006; Prasad et al., 2006; Sluijs and Brinkhuis, 2009; Frieling et al., 2014). Therefore, its general abundance to superabundance in this part of the interval may have been controlled by one or more of the previous factors. High SST may be one of the key factors that controls the superabundance of Apectodinium at higher latitude locations with a minimum temperature of approximately 20°C (Frieling et al., 2014). Since the tropical region is normally characterized by high SST, this is unlikely the main factor in the superabundance of Apectodinium in Alo-1 Well. Although, sea surface salinity (SSS) may play a minor role (few low salinity taxa are present), we suspect that the inner neritic environment and nutrient availability may be the major factors controlling the superabundance of the genus. One of the reasons that Awad and Oboh-Ikuenobe (2016) proposed for not observing a superabundance of Apectodinium was the offshore depositional nature of ODP Hole 959D.

Other important dinoflagellate cysts are the Spiniferites group (5-20 %), as well as

Impletosphaeridium spp., which comprises 10% of the assemblage in sample AL18 (438.9 m) and ~25% in sample AL14 (329.2 m). A superabundance of Impletosphaeridium spp. was observed also by Awad and Oboh-Ikuenobe (2016) in ODP Hole 959D. The abundance of Impletosphaeridium alongside Apectodinium in the two sites during the Late

Paleocene may be indicative of similar ecological affinities for some indefinable environmental parameters. The general distribution of the dinoflagellate cysts, including the presence of Palaeocystodinium spp. throughout this interval (Fig. 8) indicates a tropical, inner neritic environment with a rich nutrient availability (Wall et al., 1977; Berggren et

102 al., 2012) with fewer terrestrial palynomorphs (35-40 %) compared to the late Selandian interval.

5.3.3. Early Eocene (Ypresian, 201-54.9 m). Apectodinium is still abundant

(29.5%) in the lower part of this interval in sample AL8 (201 m, Fig. 10). Other common to superabundant taxa include the Cordosphaeridium group, the Polysphaeridium group

(mainly Polysphaeridium spp.), and Spiniferites group. Species of Adnatosphaeridium and

Glaphyrocysta, which are either absent or rare to frequent in the Late Paleocene samples, are generally abundant in samples AL4 (109.7 m) and AL2 (73 m). These genera are common in warm and nearshore marine environment (Brinkhuis, 1994; Crouch, 2001;

Slimani et al., 2010).

Polysphaeridium is indicative of warm water, restricted marine environment with high salinity and can be associated with mangrove swamps (Sluijs and Brinkhuis, 2009;

Zonneveld et al., 2013). The Polysphaeridium group (Polysphaeridium and Homotryblium) occurs mostly in the coastal, tropical-subtropical regions, where the sea surface salinity and temperature are high (Zonneveld et al., 2013). However, it has also been recorded in sediments from few offshore sites, such as the Atlantic shelf (Stover, 1977) and ODP Hole

959D (Awad and Oboh-Ikuenobe, 2016). While it is possible for cysts of the

Polysphaeridium group to be transported to offshore sites, their abundance in such settings may be due to hyperstratified conditions (Reichart et al., 2004). Therefore, the abundance to superabundance of Polysphaeridium in the upper part of Alo-1 Well may indicate a change to more restricted conditions or highly stratified conditions. This abundance of

Polysphaeridium and the presence of Spiniferites and some offshore dinoflagellate cysts

(Impagidinium aspinatum and Thalassiphora delicata, Fig. 8) in the upper part of the

103 interval may suggest a fluctuation between open marine and restricted marine conditions

(Sluijs and Brinkhuis, 2009). The terrestrial palynomorphs in all the Ypresian samples range from 20-50 %.

5.4. INFERRED LITHOSTRATIGRAPHY OF ALO-1 WELL

Sedimentary components (lithologic and palynologic) have been used to reconstruct the lithostratigraphy of Alo-1 Well. The upper ~580 m of the interval examined appear to correspond to the lower part of the Imo Formation, while the lower 180 m belong to the upper Nsukka Formation. The inferred contact between the Nsukka and Imo formations is late Selandian in age (Fig. 9). This contact is interpreted as the transition from muddy sandstone to mudstone, as deduced from the abrupt change in the sand percentage profile at ~580 m (Shell Petroleum, 1976; Fig. 3). This pattern, to an extent, is similar to the data presented by Oboh-Ikuenobe et al. (2005). The percentage of terrestrial palynomorphs in Alo-1 Well was observed to have changed from <50% to >50% below ~

500 m (Fig. 10), reflecting the more proximal depositional environment of the Nsukka

Formation (Murat, 1972). There are other studies in the region where unconformities have been suggested (e.g., Oboh-Ikuenobe et al., 2005). We have confirmed these depositional gaps during the Early Eocene in the Alo-1 Well.

5.5. COMPARISON WITH OTHER LATITUDINAL DINOFLAGELLATE CYST STUDIES

We compared the Paleocene dinoflagellate cyst assemblages recorded in Alo-1

Well to those described in high latitudes of the northern and southern hemispheres (Table

104

2). Specifically, they were compared to northern hemisphere assemblages studied in northwest Europe (e.g., Mudge and Bujak, 1996), Western Siberia (e.g., Iakovleva, 2011), and Greenland (e.g., Nøhr-Hansen et al., 2011). The data used for comparison in the southern hemisphere were obtained from the following localities: New Zealand (e.g.,

Crouch et al., 2014), Southern Chile (e.g., Quattrocchio, 2009), and offshore Tasmania

(e.g., Bijl et al., 2013).

Alo-1 Well assemblages differ considerably from those in the high latitude localities noted above. Notable absences include Paleocene taxa of biostratigraphic importance, such as Apectodinium augustum, Cribroperidinium wetzelii, Eisenackia margarita, Eisenackia reticulata, Isabelidinium spp., Manumiella druggii,

Palaeoperidinium pyrophorum and Trithyrodinium evittii. Representatives of the

Wetzellielloidea subfamily (e.g., Dracodinium simile, Rhombodinium subtile, Wetzeliella astra, W. meckelfeldensis) and Deflandrea phosphoritica are absent in the studied interval.

Species of Dracodinium and Wetzeliella are particularly important in Ypresian biostratigraphy of the North Sea Basin, where the Wetzellielloidea subfamily underwent significant evolution and diversification during this time interval (Bujak and Brinkhuis,

1998).

Dinoflagellate cysts identified in this study that are common components of high latitude assemblages of both hemispheres include Apectodinium homomorphum,

Apectodinium hyperacanthum, Apectodinium quinquelatum, Areoligera gippingensis,

Glaphyrocysta divaricata, Glaphyrocysta ordinata, Hystrichosphaeridium tubiferum,

Spinidinium densispinatum, Palaeocystodinium golzowense, Phelodinium magnificum,

Thalassiphora delicata and Spiniferites spp.

105

Fig. 10. Quantitative distribution (in percent) of selected dinoflagellate cyst assemblages in the Paleocene to Early Eocene interval. Ifecysta is the main genus of the Cordosphaeridium group. Abundances of terrestrial palynomorphs (e.g., pollen and spores) are also shown. Only samples with >100 recovered specimens are shown.

106

The dinoflagellate cyst assemblages identified in this study are more comparable to

Paleocene assemblages in mid and low latitude areas, such as the Mediterranean region

(e.g., Guasti et al., 2006; Slimani et al., 2016), equatorial West Africa (e.g., Oboh-Ikuenobe et al., 1998; Mbesse et al., 2012; Awad and Oboh-Ikuenobe, 2016), and the U.S. Gulf Coast

(Gregory and Hart, 1995; Barron et al., 2017). The dinoflagellate cysts include

Adnatosphaeridium multispinosum, Cordosphaeridium group, Eocladopyxis spp.,

Hystrichokolpoma spp., Kallosphaeridium spp., and Polysphaeridium spp. The main features of the dinoflagellate cyst distributions in Alo-1 Well are discussed below.

Table 2. Comparison between Alo-1 dinoflagellate cysts and taxa in high and mid latitudes. Taxa that are common Taxa that are Taxa that are common between high latitudes stratigraphically important between mid-latitudes and Alo-1 Well. at high latitudes and absent and Alo-1 Well in Alo-1 Well A. homomorphum A. augustum A. multispinosum A. hyperacanthum C. wetzelii Cordosphaeridium spp. A. quinquelatum D. simile Damassadinium spp. A. gippingensis E. margarita Eocladopyxis spp. G. divaricata E. reticulata Ifecysta spp. G. ordinata Isabelidinium spp. Hystrichokolpoma spp. H. tubiferum M. druggii Kallosphaeridium spp. P. golzowense P. pyrophorum Lanternosphaeridium P. magnificum R. subtile spp. S. densispinatum T. evittii Polysphaeridium spp Spiniferites spp. W. astra T. delicata W. meckelfeldensis

The Cordosphaeridium group, mainly Ifecysta, dominates the late Selandian-early

Thanetian dinoflagellate cyst assemblages in Alo-1 Well. Representatives of this group exhibit wide morphological variations in the development of apical and antapical

107 protrusions and substantial variation in the development of the periphragm, which can take the shape of processes, spines or penitabular septa. Specimens recording similar morphological features are referred to as the Kenleyia complex (Crouch et al., 2003a;

Willumsen, 2003b; Willumsen et al., 2004) occur in high percentages during the Early

Paleogene in mid latitude localities, including those in Tunisia (Brinkhuis et al., 1994;

Crouch et al., 2003a; Guasti et al., 2006), and Uzbekistan (Crouch et al., 2003a). The abundance of this group in the Alo-1 Well equatorial setting confirms its thermophilic nature.

An important finding in the present study is the abundance of Apectodinium in the studied section during the Late Paleocene (Thanetian). The timing of the Apectodinium peak appears to be approximately coeval with other Late Paleocene abundance events along the African margin (Bujak and Brinkhuis, 1998; Iakovleva et al., 2001; Crouch et al.,

2003b). Although its appearance at higher latitudes was sporadic and short-lived,

Apectodinium was frequent to abundant in low and mid latitude settings during most of the

Late Paleocene, as recorded in Alo-1 Well, Morocco (Slimani et al., 2016), Tunisia

(Crouch et al., 2003a), and Côte d’Ivoire-Ghana (Awad and Oboh-Ikuenobe, 2016).

6. CONCLUSIONS

This present study of Alo-1 Well yields important new information that is summarized as follow:

108

(1) Four biostratigraphic zones (zone E to zone H) defined by last occurrence or last

abundance bioevents of dinoflagellate cysts are recognized in the Late Paleocene-

Early Eocene of Alo-1 Well.

(2) Biostratigraphic results differ from a previous investigation carried out by Shell

Petroleum, which reported a barren interval of palynomorphs above 274 m. This

so-called “barren” interval is found to be productive in this study, and is assigned

to a late Thanetian-Ypresian age.

(3) The lithostratigraphy of Alo-1 Well is reconstructed using lithologic and

palynologic data. The upper 580 m of this well corresponds to the lower part of the

Imo Formation, while the lower 180 m belongs to the upper Nsukka Formation.

The contact between the Imo and Nsukka formations is interpreted as the transition

from muddy sandstone to mudstone, and is assigned a late Selandian age.

(4) The dinoflagellate cyst assemblages recorded in this study differ considerably from

those in high latitudes of the northern and southern hemispheres; they are more

comparable to Paleocene assemblages in mid- and low latitude areas, such as the

Mediterranean region and the U.S. Gulf Coast. In addition, other inferences are as

follow:

(a) The late Selandian to mid Thanetian is characterized by the presence of abundant

thermophilic taxa such as the Cordosphaeridium group (e.g., Damassadinium,

Fibrocysta, Ifecysta). This group displays wide morphological variations during

this time interval.

(b) The late Thanetian to Ypresian records abundant to superabundant numbers of

Apectodinium spp. This pattern is likely related to sea-surface temperatures, stable

109

oceanographic current and increase in organic productivity in marginal marine

settings that were recorded globally during the Late Paleocene to earliest Eocene

interval.

(5) In addition to dating, quantitative distribution of dinoflagellate cyst assemblages is

used to infer an inner neritic marine environment for Alo-1 Well.

ACKNOWLEDGMENTS

We acknowledge the Petroleum Research Fund (administered by the American

Chemical Society, Grant 34676-AC8 to Francisca Oboh-Ikuenobe) and the Josephine

Husbands Radcliffe Graduate Scholarship (Department of Geosciences and Geological and

Petroleum Engineering, Missouri University of Science and Technology) for funding this study. We thank the Shell Petroleum Development Company of Nigeria for providing the

Alo-1 ditch cutting samples for study. We also thank Onema Adojoh and Joel Edegbai for their detailed suggestions on an earlier draft of the manscript. We extend our appreciation to Prof. Hamid Slimani and two anonymous reviewers for taking the time and efforts to improve this paper.

110

APPENDIX A.

QUANTITATIVE DINOFLAGELLATE CYST DATA FOR ALO-1 WELL

111

201 256 384

54.9 91.4

109.7 146.3 164.6 182.9 219.4 237.7 274.3 292.6 329.2 365.8

Depth (m) Depth

AL1 AL2 AL3 AL4 AL5 AL6 AL7 AL8 AL9

AL10 AL11 AL12 AL13 AL14 AL1 AL16 Sample # Sample

Achilleodinium? sp. 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0

Achomosphaera spp. 0 0 0 0 0 8 0 0 0 0 0 1 0 0 0 0

Achomosphaera quadrata 0 1 0 14 0 22 0 1 1 0 0 1 0 0 0 0

Adnatosphaeridium spp. 0 0 0 0 1 7 1 1 2 0 0 0 0 0 1 0 Adnatosphaeridium membraniphorum 0 2 1 0 0 0 0 2 3 28 21 4 1 0 0 1 Adnatosphaeridium multispinosum 2 3 4 23 0 1 0 0 1 0 0 0 0 0 0 1

Andalusiella? sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Apectodinium spp. 2 2 1 20 0 68 6 32 232 35 3 48 15 10 6 30

Apteodinium spp. 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0

Areoligera spp. 0 7 0 0 0 0 0 0 4 0 0 1 0 0 0 0

Areoligera gippingensis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Areosphaeridium diktyoplokum 7 0 2 2 0 0 0 0 0 0 0 0 0 0 0 0

Cerodinium spp. 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cerodinium boloniense 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cerodinium glabrum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cordosphaeridium spp. 0 0 0 9 0 0 0 0 1 0 0 0 0 0 0 0 Cordosphaeridium delimurum 0 0 0 8 0 0 0 0 0 0 0 0 0 0 0 0 Cordosphaeridium fibrospinosum 0 0 0 5 0 0 0 0 0 0 0 0 0 0 0 0 Damassadinium 0 0 0 0 0 0 0 0 0 0 0 0 0 8 0 1 heterospinosum Damassadinium sp. cf. D. 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 impages

Dapsilidinium pastielsii 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Diphyes spp. 0 0 0 1 0 2 0 0 0 0 0 0 0 0 0 0 Diphyes bifidum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Diphyes colligerum 3 2 0 2 0 0 0 1 2 1 0 4 6 4 3 0

Eocladopyxis peniculata 0 3 3 18 0 6 1 4 22 1 1 8 1 3 0 0 Fibrocysta spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Glaphyrocysta spp. 4 15 6 16 0 3 1 9 2 0 0 0 1 1 8 2

Glaphyrocysta divaricata 6 5 7 7 1 5 1 11 1 0 0 2 0 0 0 0

Glaphyrocysta ordinata 4 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0

Hafniashpaera hyalospinosa 0 0 0 5 3 1 2 0 0 0 0 0 0 2 1 1

Hystrichokolpoma rigaudiae 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0

Hystrichokolpoma unispinum 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Hystrichosphaeridium 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 tubiferum

Ifecysta? sp. A 1 0 0 5 0 0 0 0 0 0 0 0 0 0 0 0

Ifecysta fusiforma 1 0 0 38 1 10 0 0 0 0 0 2 0 1 1 5

Ifecysta lappacea 0 0 0 0 0 0 0 0 1 0 0 5 0 5 1 70

Ifecysta pachyderma 0 0 0 3 1 4 4 9 15 0 5 11 1 43 2 154

Ifecysta heterospinosa 0 1 1 42 0 19 4 1 1 3 2 44 0 6 16 9

Impagidinium spp. 0 0 0 1 0 1 0 0 1 2 0 1 0 0 0 1

Impagidinium celineae 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Impagidinium aspinatum 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0

Impletosphaeridium spp. 0 7 0 1 0 6 1 0 1 0 0 3 4 41 5 13

Kallosphaeridium spp. 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1

112

Kallosphaeridium 0 2 0 1 0 3 1 0 0 0 0 0 0 0 0 0 orchiesense

Lanternosphaeridium spp. 0 0 1 0 0 7 0 4 0 0 0 0 0 21 0 5

Lejeunecysta sp. 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0

Magallanesium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 densispinatum

Muratodinium fimbriatum 1 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Oligokolpoma sp. A 0 0 0 2 0 0 0 0 0 0 0 0 0 1 0 3

Operculodinium spp. 2 4 1 5 0 7 0 1 1 1 0 5 0 1 2 14

Operculodinium tiara 4 5 1 0 0 2 0 1 0 0 0 7 1 3 2 0

Palaeocystodinium 8 2 0 1 0 1 0 0 1 0 0 1 0 0 0 1 glozowense

Palaeocystodinium rafii 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Phelodinium magnificum 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0

Polysphaeridium spp. 137 57 3 11 0 2 0 3 0 0 0 0 0 0 0 0

Senoniasphaera sp. 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0

Sentusidinium spp. 3 2 0 0 0 0 0 0 0 0 0 0 0 1 0 0

Spiniferites spp. 39 23 13 25 5 111 6 23 19 4 4 17 9 10 31 10

Spiniferites microceras 68 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Spiniferites ramosus 12 0 4 8 0 12 1 0 5 0 0 3 0 6 0 1

Thalassiphora delicata 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0

Wilsonidium stellatum 0 0 0 9 0 2 0 1 0 0 0 0 0 0 0 0

Unidentified cysts 0 1 0 3 0 1 0 0 0 1 0 0 0 0 0 0

Total counted 308 151 47 318 14 338 32 108 316 48 15 165 38 167 79 323

113

5.5

695

402.3 438.9 457.2 47 493.7 530.3 548.6 566.9 585.2 603.5 621.8 658.4 676.6 713.2 731.5 768.1

Depth (m) Depth

AL17 AL18 AL19 AL20 AL21 AL22 AL23 AL24 AL25 AL26 AL27 AL28 AL29 AL30 AL31 AL32 AL33 Sample # Sample

Achilleodinium? sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Achomosphaera spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Achomosphaera quadrata 0 2 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0

Adnatosphaeridium spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Adnatosphaeridium 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 membraniphorum Adnatosphaeridium 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 multispinosum

Andalusiella? sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0

Apectodinium spp. 0 41 0 0 8 0 0 0 0 0 0 0 0 0 0 0 0

Apteodinium spp. 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 3

Areoligera spp. 0 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Areoligera gippingensis 0 0 0 0 20 0 3 2 0 4 0 0 0 0 2 0 1 Areosphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 diktyoplokum

Cerodinium spp. 0 0 0 0 0 0 0 0 0 0 0 1 1 0 2 0 0 Cerodinium boloniense 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0

Cerodinium glabrum 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 Cordosphaeridium spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Cordosphaeridium delimurum 0 3 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 Cordosphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 fibrospinosum Damassadinium 0 3 2 0 0 0 2 0 0 6 1 0 0 0 0 1 0 heterospinosum Damassadinium sp. cf. D. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 impages

Dapsilidinium pastielsii 0 0 0 0 1 0 0 0 0 2 0 0 0 0 0 0 0

Diphyes spp. 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0

Diphyes bifidum 0 0 0 0 0 0 2 1 0 5 0 0 0 0 0 0 3

Diphyes colligerum 0 3 2 0 3 0 1 0 0 4 1 1 0 0 6 0 4 Eocladopyxis peniculata 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Fibrocysta spp. 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Glaphyrocysta spp. 0 6 2 0 3 0 0 0 0 0 0 0 0 0 1 0 0 Glaphyrocysta divaricata 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Glaphyrocysta ordinata 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Hafniasphaera hyalospinosa 0 1 0 0 5 0 0 0 0 1 0 0 0 0 0 0 0

Hystrichokolpoma rigaudiae 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Hystrichokolpoma unispinum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Hystrichosphaeridium 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 tubiferum

Ifecysta? sp. A 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Ifecysta fusiforma 0 1 0 0 1 0 2 0 0 1 0 0 0 0 0 0 0

Ifecysta lappacea 1 52 4 0 42 2 53 8 2 89 4 2 1 1 78 19 0 Ifecysta pachyderma 0 67 0 1 32 8 41 0 3 34 0 4 1 0 40 0 8

Ifecysta heterospinosa 0 12 0 0 4 0 0 0 0 0 0 0 0 0 0 0 32

Impagidinium spp. 1 0 0 5 0 1 0 1 0 0 0 0 0 1 0 0 1 Impagidinium celineae 0 0 0 0 6 0 0 0 0 0 0 0 0 0 0 0 0

Impagidinium aspinatum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Impletosphaeridium spp. 10 37 0 1 0 0 16 0 0 3 4 1 0 1 8 0 6

Kallosphaeridium spp. 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 Kallosphaeridium orchiesense 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

114

Lanternosphaeridium spp. 0 1 0 0 9 0 0 0 0 0 0 0 0 0 0 0 0 Lejeunecysta sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Magallanesium densispinatum 0 0 0 0 5 0 1 0 0 0 0 0 0 0 0 0 0 Muratodinium fimbriatum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Oligokolpoma sp. A 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Operculodinium spp. 0 4 0 1 18 0 5 4 1 15 0 1 0 0 16 3 17

Operculodinium tiara 0 6 0 0 8 0 0 0 0 0 0 0 0 0 0 0 0 Palaeocystodinium golzowense 1 6 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1

Palaeocystodinium rafii 0 4 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Phelodinium magnificum 0 1 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 Polysphaeridium spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Senoniasphaera sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Sentusidinium spp. 0 0 2 0 0 0 3 0 0 0 0 1 0 0 0 0 0

Spiniferites spp. 6 57 7 10 134 5 38 6 4 22 6 3 1 1 30 5 29 Spiniferites microceras 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Spiniferites ramosus 0 8 0 0 9 0 0 0 0 0 0 0 0 0 0 0 5 Thalassiphora delicata 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Wilsonidium stellatum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Unidentified cysts 0 1 12 0 1 1 0 0 0 0 0 0 0 0 1 0 2

Total counted 18 326 33 14 324 16 171 21 11 189 16 14 4 3 187 29 111

115

APPENDIX B.

LIST OF DINOFLAGELLATE CYST TAXA

116

Achilleodinium? sp.

Achomosphaera spp.

Achomosphaera quadrata Antolinez and Oboh-Ikuenobe, 2007

Adnatosphaeridium membraniphorum Jan du Chêne and Adediran, 1985

Adnatosphaeridium multispinosum Williams and Downie, 1966c

Andulasiella? sp.

Apectodinium spp.

Apteodinium spp.

Areoligera spp.

Areoligera gippingensis Jolley, 1992

Areosphaeridium diktyoplokum (Klumpp, 1953) Eaton, 1971

Cerodinium spp.

Cerodinium boloniense (Riegel, 1974) Lentin and Williams, 1989

Cerodinium glabrum (Gocht, 1969) Fensome et al., 2009

Cordosphaeridium spp.

Cordosphaeridium delimurum Fensome et al., 2009

Cordosphaeridium fibrospinosum Davey and Williams, 1966

Damassadinium heterospinosum (Matsuoka, 1983c) Fensome et al., 1993b

Damassadinium sp. cf. D. impages (Damassa, 1979) Fensome et al., 1993

Dapsilidinium pastielsii (Davey and Williams, 1966b) Bujak et al., 1980

Diphyes spp.

Diphyes bifidum Antolinez and Oboh-Ikuenobe, 2007

Diphyes colligerum (Deflandre and Cookson 1955) Cookson, 1965a

117

Eocladopyxis peniculata Morgenroth, 1966a

Fibrocysta spp.

Glaphyrocysta spp.

Glaphyrocysta divaricata (Williams and Downie, 1966c) Stover and Evitt, 1978

Glaphyrocysta ordinata (Williams and Downie, 1966c) Stover and Evitt, 1978

Hafniasphaera hyalospinosa Hansen, 1977

Hystrichokolpoma rigaudiae Deflandre and Cookson, 1955

Hystrichokolpoma unispinum Williams and Downie, 1966

Hystrichosphaeridium tubiferum (Ehrenberg, 1838) Deflandre, 1937

Ifecysta? sp. A

Ifecysta fusiforma Antolinez and Oboh-Ikuenobe, 2007

Ifycysta heterospinosa Antolinez and Oboh-Ikuenobe, 2007

Ifecysta lappacea (Drugg, 1970) Antolinez and Oboh-Ikuenobe, 2007

Ifycysta Pachyderma Jan du Chêne and Adediran, 1985

Impagidinium spp.

Impagidinium celineae Jan du Chêne, 1988

Impagidinium aspinatum (Cookson and Eisenack, 1974) Damassa, 1979a

Impletosphaeridium spp.

Kallosphaeridium spp.

Kallosphaeridium orchiesense de Coninck, 1975

Lanternosphaeridium spp.

Lejeunecysta sp.

Muratodinium fimbriatum (Cookson and Eisenack, 1967) Drugg, 1970b.

118

Oligokolpoma sp. A.

Operculodinium spp.

Operculodinium tiara (Klumpp, 1953) Stover and Evitt, 1978

Palaeocystodinium spp.

Palaeocystodinium golzowense Alberti, 1961

Palaeocystodinium rafii Antolinez and Oboh-Ikuenobe, 2007

Phelodinium magnificum (Stanley, 1965) Stover and Evitt, 1978.

Polysphaeridium spp.

Senoniasphaera sp.

Sentusidinium sp.

Spinidinium densispinatum (Stanley, 1965) Quattrocchio and Sarjeant, 2003

Spiniferites spp.

Spiniferites ramosus (Ehrenberg, 1838) Mantell, 1854

Spiniferites microceras (Cookson and Eisenack 1974) Mantell, 1850

Thalassiphora delicata Williams and Downie, 1966c

Wilsonidium stellatum Antolinez and Oboh-Ikuenobe, 2007

119

APPENDIX C.

SYSTEMATIC PALEONTOLOGY

120

The Systematic classification and nomenclature of dinoflagellate cysts follows

Fensome et al. (1993) and Williams et al. (2017). The terminology follows Evitt (1985) and Williams et al. (2000).

Division DINOFLAGELLATA (Bütschli, 1885) Fensome et al., 1993

Subdivision DINOKARYOTA Fensome et al., 1993

Class DINOPHYCEAE Pascher, 1914

Subclass PERIDINIPHYCIDAE Fensome et al., 1993

Order GONYAULACALES Taylor, 1980

Suborder GONYAULACINEAE Norris, 1978 (autonym)

Genus Ifecysta Jan du Chêne and Adediran, 1985

Type: Ifecysta pachyderma Jan du Chêne and Adediran, 1985

Ifecysta? sp. A.

Fig. 5, K-L

Description. Cysts assignable to Ifecysta? sp. A. are chorate, have a spherical to subspherical central body, fibrous endophragm and periphragm and a distinct antapical horn-like protrusion with outward projection of the periphragm. Fibrous expansions at the top of this protrusion usually present. Apical horn-like protrusion may be insinuated but is always poorly developed. Processes mesotabular, strongly fibrous, hollow, buccinate and nearly uniform in size. Paracingular processes strongly elongated transversely

(taeniate). Paratabulation formula 4’, 5-6’’, 6c, 5’’’, 1’’’’, 3?s. Archeopyle precingular, type P3”, operculum free.

Dimensions. 45-65 μm long, 45-60 μm wide, processes 20-25 μm long (6 specimens measured).

121

Stratigraphic range. Ifecysta? sp. A. was observed in Alo-1 Well from sample

AL1 (54.9 m) to sample AL4 (109.7 m) (Late Paleocene).

Discussion. The morphology of Ifecysta? sp. A. represents an intermediate stage between Cordosphaeridium (Eisenack, 1963) and Ifecysta (Jan du Chêne and Adediran,

1985). Cordosphaeridium has a spherical to subspherical body without horn-like protusions, while Ifecysta has a fusiform body with distinct apical and antapical protrusions. Therefore, Ifecysta? sp. A. does not exactly fit any of these generic descriptions. We consider the genus Ifecysta to be the closest fit based on the presence on an antapical horn and the insinuation of an apical horn. Ifecysta? sp. A. differs from other species of Ifecysta in lacking a distinct apical horn-like protrusion and having fibrous, buccinate, mesotabular processes.

Genus Oligokolpoma Fensome et al., 2009

Type: Oligokolpoma tubulus Fensome et al., 2009

Oligokolpoma sp. A.

Fig. 6, M-N

Description: Chorate gonyaulacoid cyst, with ovoidal central body, acavate.

Processes mesotabular of variable morphology including tubiform, flared and buccinate.

Paracingular processes not clearly observed. Parasulcal processes distinctly thinner than pre- and postcingular processes. All processes except antapical are fenestrate, distally open and have denticulate distal margins or short tubules at their distal ends; antapical process is exceptionally large and bulbous in shape. Archeopyle apical, type (tA), operculum free.

122

Dimensions. 55-60 μm long, 55-70 μm wide. Processes 15 μm long; antapical process 25-30 μm long (7 specimens measured).

Stratigraphic range. Oligokolpoma sp. A was observed in Alo-1 Well from sample

AL4 (109.7 m) to sample AL18 (438.9 m) (Late Paleocene).

Discussion. Specimens described here fit the generic description of Oligokolpoma

(Fensome et al., 2009), which include taxa whose morphology generally resembles

Hystrichokolpoma spp. (Klumpp, 1953) but lack paracingular processes. The fenestrate of the processes and the short tubules that characterize the distal ends of the processes in

Oligokolpoma sp. A. differentiates this species from Oligokolpoma tubulus, which is the only other species of the genus.

123

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III. LATE PALEOGENE-EARLY NEOGENE DINOFLAGELLATE CYST BIOSTRATIGRAPHY OF THE EASTERN EQUATORIAL ATLANTIC

Walaa K. Awad, Francisca E. Oboh-Ikuenobe

Geology and Geophysics Program, Department of Geosciences and Geological and

Petroleum Engineering, Missouri University of Science and Technology, 129 McNutt

Hall, Rolla, MO 65409-0410, USA

ABSTRACT

Six dinoflagellate cyst biozones (zone 1-zone 5, subzones 1a and 1b) are recognized in the late Paleogene-early Neogene interval of the Ocean Drilling Program (ODP) Site

959 (Hole 959A), Côte d’Ivoire-Ghana Transform Margin in the eastern Equatorial

Atlantic. The biozones are based on palynological analysis of 30 samples covering a 273.2- m interval with generally fair preservation and good to poor recovery. We propose a new age of Late Eocene (Priabonian) for subunit IIB as opposed to the previously published mid-Early Oligocene age (middle Rupelian). This age assignment is mainly based on the presence of Late Eocene marker taxa, such as Hemiplacophora semilunifera and

Schematophora speciosa in the lower part of the studied interval. We also document for the first time a hiatus event within dinoflagellate cyst zone 3, based on the last occurrences of several taxa. This interval is assigned to an Early Miocene age and is barren of other microfossils. Furthermore, we propose new last occurrences for two species. The last occurrence of Cerebrocysta bartonensis is observed in the late Aquitanian-early

Burdigalian in this study vs. Priabonian-early Rupelian in mid and high latitude regions.

Also, the last occurrence of Chiropteridium galea extends to the latest Early Miocene

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(Burdigalian) in ODP Hole 959A; this event was previously identified in other studies as

Chattian in equatorial regions, and Aquitanian in the Northern Hemisphere mid-latitudes.

We suspect that these differences are due to physical (offshore vs. nearshore) and latitudinal locations of the areas studied.

Key words: Dinoflagellate cysts; late Paleogene-early Neogene; biostratigraphy; West

Africa.

1. INTRODUCTION

The Paleogene-Neogene is considered a very important and significant time in

Earth’s history because of its natural climate change. The Paleocene-Early Eocene climate is considered the warmest during the Cenozoic Era with CO2 levels five times more than the present levels (Sluijs et al., 2007; Zachos et al., 2008; Stassen et al., 2012; McNeil and

Parsons, 2013). Subsequent cooling conditions throughout the Middle-Late Eocene to

Early Oligocene culminated in a significant drop in sea level during the Oligocene that is characterized by low carbonate sedimentation rates, planktonic diversity and productivity

(Zachos et al., 2008). The global climatic cooling during the Late Eocene-Oligocene forced several organisms to migrate from high latitude to low latitude regions. This has led to problems with biostratigraphic calibrations due to the diachronous events between latitudes

(Van Simaeys et al., 2004, 2005). While Van Simaeys et al. (2005) proposed factors other than climate that made the Oligocene more complicated and problematic in the North Sea

Basin, these factors were more widespread and include: a) the rarity of calcareous nannoplankton due to the siliciclastic nature of most deposits; b) weak paleomagnetic

133 signals; and c) most importantly, hiatus events that were very common and globally widespread.

In the present study, 30 samples (S1-S30, 193.25-466.45 mbsf) from the Priabonian to the Burdigalian interval in ODP Hole 959A, Côte d’Ivoire-Ghana Transform Margin,

West Africa were analyzed for their palynological contents. Previous palynological studies by Oboh-Ikuenobe et al. (1997, 1999) on more than 100 samples from ODP sites 959, 960,

961 and 962 focused mostly on palynofacies analysis to better understand the depositional environment, paleobathymetry of the basin, and thermal evolution of the sediments. In addition, Oboh-Ikuenobe et al. (1998, 1999) studied palynomorph contents (dinoflagellate cysts, pollen and spores) to assist in the age assignment for some intervals in these ODP sites. Shafik et al. (1998a, 1998b) used calcareous nannoplankton to establish the age of the Oligocene-Early Miocene interval for ODP Hole 959A, and erected biozonations for this part of the interval and determined the Oligocene-Miocene boundary.

Although most biostratigraphic data on the Oligocene-Early Miocene are mainly for nearshore sediments in mid-high latitudes (e.g., Brinkhuis et al., 1992; Van Simaeys et al., 2005; Soliman, 2012; Soliman et al., 2012), few studies have been published on low latitudes (e.g., Helenes and Cabrera, 2003; Williams et al., 2004; Willumsen et al., 2014).

Helenes and Cabrera (2003) indicated that the low diversity of dinoflagellate cysts in equatorial regions vs. high diversity in higher latitudes plays an important role in the sparse information about equatorial region zonations. Therefore, the main objective of the present study is to erect dinoflagellate cyst zonations for an offshore location (ODP Hole 959A) near the equator and calibrate the (sub)zones with the calcareous nannoplankton (sub)zones of Shafik et al. (1998a, 1998b) using the first and last occurrence events of dinoflagellate

134 cysts. Furthermore, we discuss the transition between the Eocene-Oligocene and the

Oligocene-Miocene boundaries and compare the proposed zonations with studies from other areas (e.g., Zevenboom, 1995; de Verteuil and Norris, 1996; Munsterman and

Brinkhuis, 2004; Pross et al., 2010).

2. GEOLOGIC SETTING

Four ODP sites (959-962) were drilled on the Côte d’Ivoire-Ghana Transform

Margin in the eastern Equatorial Atlantic, West Africa (January-February 1995). Site 959

(959A, 959B, 959C, 959D) has the most complete stratigraphic sequence with a maximum penetration in Hole 959D at 1158.9 meter below sea floor (mbsf). The maximum depths at the other holes are 480.7 mbsf in Hole 959A, 184.4 mbsf in Hole 959B, and 179.6 mbsf in

Hole 959C (Fig. 1). Cretaceous to Pleistocene strata were recorded at sites 959-962 and provided very important information about the sedimentology, stratigraphy and structure of the region. This information was used to better understand the thermal evolution, sedimentary processes, tectonics, deformation history, and paleoceanography of the eastern

Equatorial Atlantic (Mascle et al., 1996; Hisada et al., 1998).

2.1. TECTONICS

The Côte d'Ivoire-Ghana Margin Ridge (CIGMR) was initiated during an initial continental rifting phase between Africa and South America during the Early Cretaceous.

Thereafter, during a syntransform stage, an oceanic crust formed in the course of the separation of the two continents in Aptian-Cenomanian times. Next, the Cenomanian was

135 characterized by an intensive deformation of the top of the CIGMR. Finally, the passive margin post-Cenomanian stage experienced very little tectonic activities (Benkheil et al.,

1998; Pickett and Allerton, 1998). Carbonate sediments dominated the Late Cretaceous interval, and the deposition of the sediments became more stable during the Paleogene period with more pelagic sedimentation. Some extensional structures affected the Cenozoic sediments, and strong submarine erosions represented by canyon and wide submarine valleys occurred during major lowstands (Shipboard Scientific Party, 1996).

Fig. 1. Map showing the location of ODP Site 959 (indicated by red circle) in the Côte d’Ivoire-Ghana (CIG) Transform Margin in the eastern Equatorial Atlantic, West Africa (modified from Frieling et al., 2018).

2.2. LITHOSTRATIGRAPHY

Shipboard Scientific Party (1996) divided the sediments into five lithological units

(I to V downsection) described in Table 1 (see also Fig. 2). Alternation from darker to lighter color of the calcareous sediments downunit has been used to subdivide Unit I into subunits IA and IB. Unit II is predominantly comprised of siliceous phases and subdivided into three subunits based on the dominance of diagenetic sediments as follows: diatomite

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(IIA), chert (IIB), and porcellanite (IIC). Unit III is characterized by deep shelf claystone with slight to moderate bioturbation. Unit IV, which has two subunits IVA and IVB, comprises calcareous sediments indicative of shallow marine deposition. Thin, well sorted and laminated and cross-laminated sand beds of Unit V are indicative of deep-water lacustrine setting.

3. MATERIAL AND METHODS

The 30 samples selected for this study (S1-S30) were processed from subunits IIA and IIB and lower part of subunit IB of ODP Hole 959A (Fig. 2; Tables 1 and 2). Standard palynological processing methods (Traverse, 2007) were used to extract the organic fraction of the samples by digesting the sediments in HCL and HF, and separation of the organic matter in heavy liquid (ZnBr2). The organic residues were oxidized using Schultze solution (KClO3 plus HNO3), and screened through 10 μm sieves. Half of the oxidized residues were stained with safranin red. A minimum of 300 dinoflagellate cysts was counted per slide in few productive samples in order to estimate the relative abundance of each taxon; majority of the samples have poor recovery.

Estimates for the total dinoflagellate cysts in a slide were converted to percentages and discussed as follows: rare (<1-5%), few (5-10%), common (10-20%), abundant (20-

40%) and superabundant (>40%). For identification and descriptions of the dinoflagellate cysts, a Nikon transmitted light microscope with interference contrast was used. All the palynological slides used in this study are stored in the palynological repository located in the Paleontology Laboratory at Missouri University Science and Technology, USA. The

137 plate captions contain details of the illustrated specimens, which include the sample number, and England Finder (EF) reference. The systematic classification and nomenclature of dinoflagellate cysts follow Fensome et al. (2008) and Williams et al.

(2017), and the descriptive terminology follows Evitt (1985) and Williams et al. (2000).

Shafik et al. (1998a, 1998b) calibrated the calcareous nannoplankton data in ODP Hole

959A with the geologic timescale of Berggren et al. (1995).

4. PREVIOUS BIOSTRATIGRAPHIC STUDIES

The age assignment for ODP sites 959, 960, 961 and 962 was determined by several microfossils (Oboh-Ikuenobe et al., 1997, 1998, 1999; Shafik et al., 1998a, 1998b; Norris,

1998), although some intervals could not be dated due to the absence of mineralized microfossils. For ODP Hole 959A, dinoflagellates cysts, pollen, spores, planktonic foraminifera and calcareous nannoplankton have been used for analyses. The assemblage composition for each of these microfossil groups is discussed below.

Oboh-Ikuenobe et al. (1997, 1999), although focused on palynofacies, used pollen, spores and dinoflagellate cysts to analyze the Oligocene-Miocene interval in ODP Hole

959A. Dinoflagellate cysts represented the majority of their recovered specimens because of the offshore nature of the studied interval, and the long biostratigraphic ranges of most dinoflagellate cysts limited the precise age assignment. However, they observed some important dinoflagellate cysts that are biostratigraphically useful in the Oligocene age, such as Spiniferites mirabilis and Hystrichokolpoma cinctum. They also used pollen and spores with dinoflagellate cysts to support their age assignment, for example,

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Retibrevittricolporites obodoensis and Spirosyncolpites bruni, which became common in the Early Miocene.

Norris (1998) analyzed planktonic foraminifera in the lower Middle Miocene to

Lower Miocene interval in ODP Hole 959A. Although the preservation of specimens declined in zone N10, he used the first and last appearance datums of some important taxa in erecting zones through this interval. Typical Early Miocene planktonic foraminifera taxa present in zone N7 through N4 included Fohsella birnageae, Fohsella kugleri,

Globigerinatella insueta and Praeorbulina sicana. The Oligocene-Miocene boundary was not observed because the samples from 159-959A-28X through 37X (264.4-351.2 mbsf) contain radiolarian and diatom assemblages with rare benthic and planktonic foraminifera.

Only a short interval from samples 159-959A-38X-CC through 40X-CC (360.8-380.2 mbsf) recorded some Oligocene assemblages, as Globigerinella obesa, Globigerina praebulloides and Globigeria euapertura. The samples from 159-959A-41X to the bottom of Hole 959A (389.8-480.7 mbsf) were barren of planktonic foraminifera.

Shafik et al. (1998a, 1998b) used calcareous nannoplankton in ODP Hole 959A to propose bio (sub)zones (CP18/CN4) through the Early Oligocene-Miocene interval.

Although they had some barren samples in this interval, they were able to determine some of the exact boundaries between the bio (sub)zones, in addition to the transition between the Oligocene-Miocene. Samples from the basal 53 m (427.7-480.7 mbsf) were barren of calcareous nannoplankton, and zone CP18 was assigned to a late Rupelian-early Chattian age. The occurrence of the marker species Sphenolithus distentus and Sphenolithus ciperoensis in samples 159-959A-42X-CC through 40X-CC (399.2-380.2 mbsf) was used to indicate zone CP18 and the base of zone CP19.

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Table 1. Summary of the lithostratigraphy of ODP site 959. Unit Age Thickness (m) Subunit Description I Holocene to 208 IA Nannofossil ooze and foraminifera ooze; Early slight to moderate bioturbation. Miocene IB Nannofossil/foramnifera ooze changing gradually to nannofossil/foraminifera chalk; glauconite percentage increases with consistent color bands at the base of the subunit. II Early 599.3 IIA Diatomite with siliceous fauna and flora Miocene to and interbedded intervals of nannofossil Late chalk, diatom nannofossil chalk, clayey Paleocene diatom nannofossil chalk, and diatomite with clay; deep bathyal trace fossil assemblage predominant (e.g., Zoophycos, Chondrites and Planolites) in association with several authigenic minerals, such as pyrite, dolomite and glauconite. IIB Black chert and claystone with pyrite-rich intervals as nodules within the clay-rich sediments; upper boundary of subunit determined by the first occurrence of chert with decreasing siliceous components, and the base is identified by the last occurrence of chert. IIC Porcellanite, micrite and clay with abundant pyrite and organic debris. III Late 231 N/A Black claystone, claystone with Paleocene to nannofossils, and many authigenic early minerals (e.g., barite, pyrite, and Coniacian glauconite); a variety of trace fossils, such as Planolites and Zoophycos also present. IV Early 38.4 IVA Sandy limestone, sandy dolomite and Coniacian to calcareous sandstone; bioturbation high at early some levels in the sandy dolomite; Turonian and foraminifera and nannofossils present in older the sandy limestone. IVB Limestone with skeletal and intraclastic wackestones and packstones; subunit has coarser clastic rocks that reflect high energy and nearshore environment. V Late Albian 77.2 N/A Quartz sandstone and silty claystone with sharp upper contact and rippled lower boundary; characterized by sedimentary structures, such as hummocky cross- bedding, swale bed forms, and trough cross-bedding.

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Fig. 2. The lithostratigraphy of ODP Site 959 (units I to V) (modified from Shipboard Scientific Party,1996) and sample horizons in the studied interval. Note the contrast between the proposed Priabonian age for subunit IIB in the sample column to the right, versus the lower Oligocene proposed by the Shipboard Scientific party (1996).

A Chattian age was proposed for zone CP19 and subzone CN1a. The uppermost

Oligocene assemblage (subzone CN1a) in samples 159-959A-37X-CC through 32X-5,

129-130 (351.2-303 mbsf) includes such distinctive and abundant calcareous nannoplankton as Cyclicargolithus abisectus, C. floridanus and Discoaster deflandrei.

Shafik et al. (1998a, 1998b) placed the Oligocene-Miocene boundary at approximately between samples 159-959A-32X-5, 129-130 (~303 mbsf) and 159-959A-31X-CC (293.3 mbsf) based on the end of the acme of Cyclicargolithus abisectus (top of

Oligocene/subzone CN1a). They proposed earliest Miocene age for subzones CN1b and

141

Table 2. List of samples, core-section, interval, Missouri University of Science and Technology Repository no. (showing slide no) and sample depths for ODP Hole 969A; mbsf = meter below sea floor. Samples ODP Log 159, Hole Repository No. Depth (mbsf) 959A, Core-section, Interval (cm) S1 21X-03, 115-117 MST-1863-SL2 193.25 S2 22X-02, 40-43 MST-1864-SL2 200.5 S3 23X-02, 0-4 MST-1865-SL1, SL2 209.10 S4 23X-05, 17-21 MST-1866-SL2 213.77 S5 24X-02, 61-65 MST-1867-SL1, SL2 218.72 S6 24X-05, 95-99 MST-1868-SL1, SL2 223.55 S7 25X-04, 136-139 MST-1869-SL1, SL2 231.66 S8 25X-07, 44-48 MST-1870-SL2 235.24 S9 26X-03, 137-141 MST-1871-SL1, SL2 239.87 S10 26X-07, 11-15 MST-1872-SL1, SL2 244.61 S11 28X-01, 118-123 MST-1873-SL1, SL2 255.98 S12 28X-06, 39-44 MST-1874-SL1, SL2 262.69 S13 29X-05, 41-45 MST-1875-SL1, SL2 270.81 S14 30X-01, 23-27 MST-1876-SL1 274.23 S15 31X-01, 16-18 MST-1877-SL1, SL2 283.86 S16 31X-05, 44-47 MST-1878-SL1 290.14 S17 32X-01, 51-54 MST-1879-SL1 293.81 S18 32X-04, 15-18 MST-1880-SL1 297.95 S19 33X-02, 143-146 MST-1881-SL1, SL2 305.93 S20 33X-06, 70-73 MST-1882-SL1 311.20 S21 34X-04, 84-89 MST-1883-SL1, SL2 317.94 S22 37X-02, 58-61 MST-1884-SL1, SL2 343.58 S23 41X-06, 111-115 MST-1885-SL1, SL2 388.81 S24 42X-03, 128-131 MST-1886-SL1, SL2 394.08 S25 43X-01, 5-8 MST-1887-SL1, SL2 399.25 S26 44X-03, 21-24 MST-1888-SL1, SL2 411.77 S27 45X-03, 22-24 MST-1889-SL1, SL2 421.32 S28 46X-04, 113-115 MST-1890-SL1, SL2 433.33 S29 47X-02, 56-61 MST-1891-SL1, SL2 439.46 S30 50X-CC, 15-20 MST-1892-SL1, SL2 466.45

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CN1c, where the last occurrence (LO) of Orthorhabdus serratus was determined at the base of subzone CN1c. Finally, Shafik et al. (1998a, 1998b) easily identified the base of both zones CN2 and CN3 (Aquitanian-Burdigalian) based on the LO of Sphenolithus belemnos and Sphenolithus heteromorphus, respectively.

5. DINOFLAGELLATE CYST ZONATIONS

Eighty-one dinoflagellate cyst taxa were identified in the studied interval in ODP

Hole 959A (Appendix A). The preservation is generally fair, while the recovery ranges from good to poor and some samples are not very productive. In the present study, we propose six dinoflagellate cyst biozones (zone 1-zone 5 including subzones 1a and 1b; Figs.

3 and 4) in the Priabonian to Burdigalian interval of ODP Hole 959A. Although most of the recovered taxa have long ranges throughout the interval, which limit their use in the age assignment, some biomarker species are present (Figs. 3 and 4). The dinoflagellate cyst biozones are either interval zones or assemblage subzones. The interval zones are defined by the first occurrences (FOs) and/or last occurrences (LOs) of important biostratigraphic dinoflagellate cyst taxa, while the assemblage subzones are based on the overlapping ranges of assemblage co-occurring taxa. A summary diagram (Fig. 4) describes the dinoflagellate cyst biozones and calcareous nannoplankton (sub)zones of ODP Hole 959A

(Shafik et al., 1998a, 1998b); dinoflagellate cyst zonations of mid-high latitude regions are shown to the right-hand side for comparison.

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5.1. ZONE 1

Definition. The top of the zone is defined by the FOs of Achomosphaera grallaeformis and Tuberculodinium vancampoae. The base of the zone is not defined in the present study. We divide zone 1 into two assemblage subzones, subzone 1a and subzone

1b.

5.1.1. Subzone 1a. Characteristic taxa. Species of Batiacasphaera hirsuta (Fig.

5C), Dapsilidinium pseudocolligerum (Fig. 5L), Reticulatosphaera actinocoronata (Fig.

9D), and Selenopemphix nephroides (Fig. 9H) have their FOs within subzone 1a (sample

S30), together with spot occurrences (SOs) of Cordosphaeridium cantharellus (Fig. 5I),

Distatodinium ellipticum (Fig. 6A), Hemiplacophora semilunifera (Fig. 6E-G) and

Schematophora speciosa (Fig. 9E-F) (Fig. 3). This subzone is barren of calcareous nannoplankton; therefore, the age assignment in this part has been inferred from marker dinoflagellate cyst taxa observed in other studies (e.g., Wilpshaar et al., 1996; Williams et al., 2004; Kӧthe and Piesker, 2007).

Age range. Late Eocene (Priabonian) ODP Hole 959A, 26.99 m thick, from sample

S30 (466.45 mbsf) to sample S29 (439.46 mbsf).

Comments. A new age (Priabonian) is proposed for subunit IIB based on the dinoflagellate cyst assemblages within subzone 1a; this age is different from a previous assignment by the Shipboard Scientific Party (1996) as middle Rupelian age. Subunit IIB in ODP Hole 959A ranges from 456.6 to 480.7 mbsf and this interval is completely barren of calcareous nannoplankton (Shipboard Scientific Party, 1996; Shafik et al., 1998a,

1998b). The assigned age of the Shipboard Scientific Party (1996) depends mainly on one sample at depth 465.3 mbsf from ODP Hole 959D, which contains common, well preserved

144 calcareous nannoplankton. The presence of the dinoflagellate cysts H. semilunifera and S. speciosa in the present study with other Late Eocene assemblages in sample S30 (the only sample representing subunit IIB in the studied interval), supports a Priabonian age for this part. Both dinoflagellate cyst specimens were originally described from the Australian

Eocene sections and boreholes (Deflandre and Cookson, 1955; Cookson and Eisenack,

1965). These two specimens have been recorded in several Late Eocene studies (Williams,

1978; Head and Norris, 1989; Brinkhuis and Biffi, 1993; Brinkhuis et al., 2003a, 2003b;

Sluijs et al., 2003). Williams et al. (2004) also observed the entire stratigraphic range of H. semilunifera and S. speciosa at different latitudes during the Eocene. They recorded the

LO of H. semilunifera at 35.2 ma and 35.4 ma in the Priabonian of the equatorial regions and Southern Hemisphere mid latitudes, and Southern Hemisphere high latitudes, respectively. In the same study, the total range of S. speciosa was mainly restricted to the

Priabonian in equatorial regions, and mid and high latitudes in the Southern Hemisphere.

Furthermore, other species whose range include Late Eocene age such as C. cantharellus,

D. ellipticum, R. actinocoronata, and S. nephroides are also observed in the same sample

(S30) with H. semilunifera and S. speciosa (Eaton, 1976; Bujak et al., 1980; Brinkhuis,

1994; Williams et al., 2004; Kӧthe and Piesker, 2007).

5.1.2. Subzone 1b. Characteristic taxa. The FOs of several taxa are observed within subzone 1b, such as Cerebrocysta? namocensis (Fig. 5F), Homotryblium tenuispinosum

(Fig. 6J-K), Hystrichokolpoma cinctum (Fig. 7A), Lejeunecysta fallax (Fig. 7I),

Selenopemphix armata (Fig. 9G), Spiniferites mirabilis (Fig. 9I) and Spiniferites pseudofurcatus (Fig. 9J), in addition to SOs of Hystrichokolpoma pusillum (Fig. 7B),

Homotryblium vallum (Fig. 6L-M), and Kallosphaeridium biornatum (Fig. 7C).

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Abundance of Spiniferites pseudofurcatus and superabundance of Homotryblium spp. (Fig.

6I-M) are observed in samples S27 and S28, respectively (Figs. 3 and 4). The upper boundary of zone 1 (subzone 1b) is equivalent to calcareous nannoplankton zone CP18, while the lower part is barren of calcareous nannoplankton.

Age range. Early Oligocene (Rupelian), ODP Hole 959A, 45.38 m thick, from sample S29 (439.46 mbsf) to sample S24 (394.08 mbsf).

Comments. The SOs of both H. pusillum and H. vallum in the middle of subzone

1b in samples S29 and S28, respectively (Fig. 3) indicates a Rupelian age for this part of the interval. The FO of H. pusillum was previously assigned to the Rupelian in the

Mediterranean region and used to define the top of the Corrudinium incompositum (Cin) biozone Wilpshaar et al. (1996) and Pross et al. (2010) (Fig. 4). H. vallum was originally recorded from the Rupelian of an offshore site in the Blake Plateau (Stover, 1977). This species spans a very short interval in the Rupelian of a borehole in Germany within dinoflagellate cyst subzone D12nc (Fig. 4; Kӧthe and Piesker, 2007). Brinkhuis (1994) considered the FO of H. vallum as an important stratigraphic event recognizing the

Rupelian age. In addition, Helenes and Cabrera (2003) observed the FO of this species in the early Rupelian in eastern Venezuela. Finally, the presence of other species whose range include the Rupelian -supports the age assignment for this part of the interval, and they include B. hirsuta, D. pseudocolligerum, K. biornatum, L. fallax, and R. actinocoronata

(Stover, 1977; Biffi and Grignani, 1983; Poulsen et al., 1996; Guerstein et al., 2008; Bijl et al., 2018). Kӧthe and Piesker (2007) recorded the FO of R. actinocoronata within dinoflagellate cyst subzone D12nc (Priabonian-early Rupelian), and the FOs of B. hirsuta,

D. pseudocolligerum and L. fallax in zone D14 (Rupelian) (Fig. 4).

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Fig. 3. Range chart of selected dinoflagellate cysts. The proposed (sub)zones (zone 1-zone 5, subzones 1a and 1b) in the study interval are shown to the right alongside the calcareous nannoplankton zonations of Shafik et al. (1998a, 1998b).

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We note here some difficulty comparing the Oligocene bioevents in ODP Hole

959A with those in some other sections in the southern North Sea Basin (Van Simaeys et al., 2005), Germany (Kӧthe and Piesker, 2007), and Umbria-Marche Basin in Italy

(Zevenboom, 1995; Pross et al., 2010) (Fig. 4). Few significant stratigraphic taxa are common between the sections and are used for correlation. However, the difference in paleolatitude between the European sections and the CIGMR site, as well as the nearshore nature of these sections vs. the offshore nature of the present study limit this comparison due to differences in assemblages. Also, low-resolution sampling in ODP Hole 959A is considered a principal factor contributing to the absence of some marker species; for instance, Rupelian markers such as Chiropteridium lobospinosum and Enneadocysta pectiniformis are not recovered between samples S30 and S29. Furthermore, some important global bioevents noted in different parts of the world are also used to assist in the age assignment (e.g., Zevenboom, 1995,1996; Williams et al., 2004).

5.2. ZONE 2

Definition. The base of the zone is defined by the FOs of Achomosphaera grallaeformis and Tuberculodinium vancampoae. The top of the zone is defined by the FO of Membranilarnacia? picena.

Characteristic taxa. The FOs of Achomosphaera grallaeformis (Fig. 5A),

Brigantedinium? spp. (Fig. 5D), Habibacysta tectata (Fig. 6C-D), Pentadinium laticinctum

(Fig. 8E-F), and Tuberculodinium vancampoae (Fig. 9L) are recorded in the lower part of this zone in samples S24 and S23. This part of the interval is equivalent to calcareous nannaoplankton zones CP18 and CP19 (Fig. 3). Furthermore, several FOs of dinoflagellate

148 cyst taxa occur in sample S22 in the middle of zone 2: Cerebrocysta bartonensis (Fig. 5E),

Cribroperidinium tenuitabulatum (Fig. 5K), Kallosphaeridium capulatum (Fig. 7D),

Nematosphaeropsis labyrinthus (Fig. 8G-H), and Nematosphaeropsis lemniscata (Fig. 8I-

J). In the upper part of this zone, the LO of P. laticinctum and the FO of Chiropteridium galea (Fig. 5G-H) coincide with a superabundance of Polysphaeridium zoharyi (Fig. 9A-

B) in sample S21 (Figs. 3 and 4).

Fig. 4. Comparison between the proposed dinoflagellate cyst (sub)zones in the Late Eocene to Early Miocene of ODP Hole 959A with other zonations.

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This is followed by the FOs of Heteraulacacysta campanula (Fig. 6H), and

Membranilarnacia? picena (Fig. 8C-D), and an abundance of B. hirsuta in sample S20.

The lower boundary of zone 2 is correlated to the middle part of calcareous nannoplankton zone CP18, and the upper boundary is equivalent to the top of calcareous nannoplankton subzone CN1a.

Age range. Late Oligocene (Chattian), ODP Hole 959A, 82.88 m thick, from sample S24 (394.08 mbsf) to sample S20 (311.20 mbsf).

Comments. The sample resolution is very low throughout zone 2 (Fig. 3), which limits refining the results in this part of the interval, and probably resulted in the absence of some zonal Chattian markers, such as Distatodinium biffii, whose FO has been used in

Europe to delineate the upper boundary of (Clo) zone (Pross et al., 2010) and NSO-4b subzone (Van Simaeys et al., 2005) (Fig. 4). Therefore, we estimate that the Rupelian-

Chattian boundary may be close to the FOs of both A. grallaeformis and T. vancampoae in the present study. A. grallaeformis has a stratigraphic range mostly from the Late

Oligocene to the Miocene. In ODP Hole 959A, this species is observed from the early

Chattian to the Burdigalian. It was also recorded in the Chattian of the following regions: eastern USA (de Verteuil and Norris, 1996), northern Germany (Strauss et al., 2001), and

South China Sea (Mao et al., 2004). In addition, A. grallaeformis extends to the Late

Miocene in several studies, where its LO has been recorded (e.g., Kӧthe and Piesker, 2007).

The FO of T. vancampoae was thought to be restricted to the early Aquitanian

(Stover, 1977; Williams and Bujak, 1977; Williams et al., 1993). This was later identified in the Rupelian by Brinkhuis and Biffi (1993), and the Chattian by de Verteuil and Norris

(1996). Moreover, Torricelli and Biffi (2001) use the FO of T. vancampoae as a marker

150 bioevent to recognize the Rupelian in the Tabarka Section in Tunisia. According to Van

Simaeys et al. (2005) and Pross et al. (2010), the earliest FO of T. vancampoae in their studied sections was observed in the late Rupelian within NSO-5a subzone and Clo zone, respectively (Fig. 4). The FO of this species was observed in the early Chattian in subsurface sections in eastern Venezuela (Helenes and Cabrera, 2003). The presence of other species whose range includes the Chattian throughout zone 2 gives further support to the proposed age assignment. For example, P. laticinctum was reported from the Oligocene in several localities, such as South China Sea (Mao et al., 2004), Tabarka Section, Tunisia

(Torricelli and Biffi, 2001), Monte Cagnero Section, Italy (Pross et al., 2010), and North

Alpine Foreland Basin, Austria (Soliman, 2012). K. capulatum and C. tenuitabulatum were also recorded in the same time range in some other studies (Gerlach, 1961; Stover, 1977;

Poulsen et al., 1996; Torricelli and Biffi, 2001; Helenes and Cabrera, 2003).

Superabundances of Chiropteridium spp. were recorded during the Oligocene in several sections in Italy (Brinkhuis et al., 1992; Wilpshaar et al., 1996; Pross et al., 2010), but not in the present study. We suspect that the main reasons for the absence of these events in ODP Hole 959A are the outer neritic paleoenvironment of the site and the diachronous events that were common between latitudes at that time. Chiropteridium is an inner neritic species that flourishes in high energy environments or outer neritic sittings with seasonal upwelling (Brinkhuis et al., 1992; Brinkhuis, 1994).

5.3. ZONE 3

Definition. The base of the zone is defined by the FO of Membranilarnacia? picena. The top of the zone is defined by the FO of Pyxidinopsis fairhavenensis.

151

Characteristic taxa. Restricted species within zone 3 include Lejeunecysta cinctoria (Fig. 7F-G), Lejeunecysta communis (Fig. 7H), Lejeunecysta hyalina (Fig. 7E),

Lingulodinium pycnospinosum (Fig. 8A-B) and Thalassiphora succincta (Fig. 9k). The

LOs of several taxa are observed in the middle part of this zone in samples S17 and S16:

D. pseudocolligerum, K. capulatum, L. cinctoria, L. communis, L. pycnospinosum, S. armata, and T. vancampoae. Also, the FO of Lejeunecysta globosa (Fig. 7J) coincides with the common occurrence of both H. campanula and S. pseudofurcatus in sample S16. The superabundance of P. zoharyi is recorded in both samples S18 and S17 (Fig. 4). The lower boundary of zone 3 is equivalent to the top of calcareous nannoplankton subzone CN1a, and the upper boundary falls within calcareous nannoplankton subzone CN1b.

Age range. Earliest Early Miocene (early Aquitanian), ODP Hole 959A, 27.34 m thick, from sample S20 (311.20 mbsf) to sample S15 (283.86 mbsf).

Comments. The FO of M. picena delineates the lower boundary of zone 3 and indicates an earliest Early Miocene age for this part of the interval (Figs. 3 and 4). This species has been recorded in several studies as an early Aquitanian age (Biffi and Manum,

1988; Brinkhuis et al., 1992; Zevenboom et al., 1994; Zevenboom, 1995, Wilpshaar et al.,

1996; Munsterman and Brinkhuis, 2004). Van Simaeys et al. (2004, 2005) recorded its occurrence in the late Chattian in Belgium, Germany and southern North Sea basin based on its co-occurrence with Distatodinium biffii. Munsterman and Brinkhuis (2004) considered the FO of M. picena within zone SNSM1 a very close event to the Oligocene-

Miocene boundary (Fig. 4), whereas Williams et al. (2004) reported its FO at 21.7 ma

(Aquitanian) in equatorial regions. In the present study, we consider the common occurrence of this species as earliest Early Miocene due to the absence of any late Chattian

152 marker species. Since this bioevent probably coincides with the Oligocene-Miocene boundary, the placement of the boundary between samples S20 (311.20 mbsf) and S21

(317.94 mbsf) is close to the age assignment proposed by Shafik et al. (1998a, 1998b) using calcareous nannoplankton.

Lejeunecysta cinctoria, L. communis, L. hyalina, L. pycnospinosum, and T. succincta are mainly restricted to zone 3 in ODP Hole 959A and have been recorded in several Oligocene-Miocene sediments (Benedek and Sarjeant, 1981; Biffi and Grignani,

1983; Matsuoka and Bujak, 1988; Kӧthe and Piesker, 2007; Soliman, 2012; Soliman et al.,

2012). Drugg and Loeblich (1967) originally noted the FO of H. campanula in the Middle

Eocene of the Gulf Coast. In the present study, this species is mainly restricted to the

Aquitanian age. In addition, the presence of P. fairhavenensis (Fig. 9C) at the upper boundary of zone 3 followed by Operculodinium piaseckii (Fig. 8K) in the next zone (zone

4) suggests an Aquitanian age for this part of the interval. The FOs of these species have been reported in several studies as post-dating the Oligocene-Miocene boundary (de

Verteuil and Norris, 1996; Poulsen et al., 1996; Strauss and Lund, 1992; Brinkhuis et al.,

2003a; Mao et al., 2004; Kӧthe and Piesker, 2007; Schreck et al., 2012; Soliman et al.,

2012; Bijl et al., 2018). Williams et al. (2004) reported the FO of P. fairhavenensis in the

Aquitanian of both Northern Hemisphere mid-latitudes and Southern Hemisphere high latitudes at 21.9 ma and 20.0 ma, respectively. Furthermore, Bijl et al. (2018) used the FO of P. fairhavenensis to delineate the lower boundary of zone SMDZ1 as an indicator bioevent of the Early Miocene in offshore Wilkes Land, East Antarctica. In the present study, we confirm the presence of this species in the Aquitanian in equatorial regions.

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Finally, the concentration of several LOs of dinoflagellate cyst assemblages in zone

3 may indicate a hiatus event in the earliest Early Miocene (Fig. 3). Shafik et al. (1998a,

1998b) did not notice this event in ODP Hole 959A due to the absence of calcareous nannoplankton from 293.3 to 297.3 mbsf.

5.4. ZONE 4

Definition. The base of the zone is defined by the FO of Pyxidinopsis fairhavenensis. The top of the zone is defined by the LO of M. picena.

Characteristic taxa. Several biostratigraphic events occur at the lower part of this zone: LOs of H. cinctum, L. globosa, S. nephroides in sample S14, and LOs of H. campanula and H. tenuispinosum in sample S12. The FO of Cribroperidinium giuseppei

(Fig. 5J) and the LOs of H. tectata and P. fairhavenensis are observed in sample S10. This is followed by the LOs of both C. bartonensis and L. fallax that coincide with the FO of

Exochosphaeridium insigne (Fig. 6B) in sample S9. Species with LOs toward the top of this zone include B. hirsuta, Brigantedinium? spp., C. namocensis, M. picena, O. piaseckii,

R. actinocoronata, S. mirabilis, and S. pseudofurcatus. Abundance of C. namocensis and superabundance of Batiacasphaera spp. (Fig. 5B-C) are recorded in samples S15 and S8

(Figs. 3 and 4). The lower boundary of zone 4 is equivalent to the middle of calcareous nannoplankton subzone CN1b, and the upper boundary falls within calcareous nannoplankton zone CN3 (Fig. 3).

Age range. Early Miocene (Aquitanian) to latest Early Miocene (Burdigalian), ODP

Hole 959A, 70.09 m thick, from sample S15 (283.86 mbsf) to sample S4 (213.77 mbsf).

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Comments. H. campanula, H. cinctum, and H. tenuispinosum have their LOs close to the lower boundary of this zone, and they have been observed in other sections spanning the Oligocene-Miocene boundary (Matsuoka and Bujak, 1988; Mao et al., 2004;

Munsterman and Brinkhuis, 2004; Kӧthe and Piesker, 2007). The LO of P. fairhavenensis occurs within zone 4, which is equivalent to the middle of calcareous nannoplankton zone

CN2. There is a possibility that this is the real LO of this species in the equatorial regions; however, additional studies are needed to confirm that. This bioevent is older than its LO at 15.2 ma and 15.0 ma (Middle Miocene) in the Northern Hemisphere mid-latitudes and

Southern Hemisphere high latitudes, respectively (Williams et al., 2004). O. piaseckii, which Bijl et al. (2018) considered a significant Early Miocene species, is mainly restricted to zone 4 in the present study.

In ODP Hole 959A, we propose a new LO of late Aquitanian to early Burdigalian for C. bartonensis. This bioevent is far younger than its LO of Priabonian to early Rupelian in some studies (Van Simaeys et al., 2005; Heilmann-Clausen and Van Simaeys, 2005;

Kӧthe and Piesker, 2007; Kӧthe, 2012; Fensome et al., 2016). Furthermore, the oldest LO of this species was recorded by Williams et al. (2004) in the Middle Eocene (38 ma) of the

Northern Hemisphere mid-latitudes and Southern Hemisphere high latitudes. We suspect that latitudinal differences may play an important role for this disparity. Schiøler (2005) reported the LO of Brigantedinium? spp. during the Burdigalian of the Danish North Sea, which is similar to the present study.

Few specimens of E. insigne are recorded in the upper part of zone 4 and extend to the lower part of zone 5. This species was originally observed in the Aquitanian of eastern

USA (de Verteuil and Norris, 1996). Soliman et al. (2012) described it as a key species for

155 their proposed dinoflagellate cyst zone GOS2 in the Early Miocene of the Gulf of Suez,

Egypt. This species is characterized by a short stratigraphic range, from the upper part of calcareous nannoplankton zones CN2 to CN3 (Dybkjær and Piasecki, 2008, 2010) and may extend to the lower part of calcareous nannoplankton zone CN4 (Jiménez-Moreno et al.,

2006; Soliman et al., 2012). Dybkjær and Piasecki (2010) proposed a new FO of E. insigne in Denmark based on Sr-isotope analysis that indicated a Burdigalian age (between 18.7

Ma and 20 Ma). This is different from the Aquitanian (mainly restricted calcareous nannoplankton zone CN2) assignment for this species by de Verteuil and Norris (1996). In

ODP Hole 959A, the FO of E. insigne in sample S9 (the upper part of calcareous nannoplankton zone CN2) followed by the LO of M. picena in sample S4 (the middle of calcareous nannoplankton zone CN3) indicates a late Aquitanian to an early Burdigalian age for this part of the interval.

5.5. ZONE 5

Definition. The base of the zone is defined by the LO of M. picena. The top of the zone is not defined in the present study.

Characteristic taxa. The presence of A. grallaeformis, C. galea, C. giuseppei, C. tenuitabulatum, N. labyrinthus, and N. lemniscata characterizes this zone. Superabundant taxa within this zone include P. zoharyi in samples S3 and S1, and Cribroperidinium spp. in sample S2 (Figs. 3 and 4). The lower boundary of zone 5 is equivalent to the middle of calcareous nannoplankton zone CN3.

Age range. Latest Early Miocene (Burdigalian), ODP Hole 959A, 20.52 m thick, from sample S4 (213.77 mbsf) to sample S1 (193.25 mbsf).

156

Comments. Williams et al. (2004) recorded the LO of M. picena in the equatorial region at 18 ma (Burdigalian). This bioevent marked the top of dinoflagellate cyst zone

SNSM2 in the southern North Sea (Munsterman and Brinkhuis, 2004) as a late Aquitanian to an earliest early Burdigalian age. Furthermore, the same event was recorded in the

Burdigalian of the Contessa section, northern Italy (Zevenboom, 1995;1996). In the present study, the LO of E. insigne follows directly the LO of M. picena in the lower part of zone

5 within calcareous nannoplankton zone CN3 (Fig. 3). This bioevent is similar to the LO of this species in eastern North Sea Basin, Denmark (Dybkjær and Piasecki, 2010), which has a Burdigalian age.

C. galea is observed from the top of zone 2 (Chattian age) until the top of the study interval in ODP Hole 959A (Burdigalian). This species has an extended range in the present study compared to other regions (e.g., de Verteuil and Norris, 1996; Dybkjær and Piasecki,

2010; Fensome et al., 2016). C. galea extends from the early Rupelian (33.5 ma) to the middle Aquitanian (22.36 ma) in Northern Hemisphere mid-latitudes, while in the equatorial regions, its reported range is from the middle Rupelian (31 ma) to the late

Chattian (23.98 ma), respectively (Williams et al., 2004). Furthermore, Kӧthe and Piesker

(2007) recorded this species in Germany from dinoflagellate cyst subzone D14na (early

Rupelian) to zone D15 (late Chattian) (Fig. 4). Therefore, we propose a new stratigraphic range for C. galea that may extend to the Burdigalian in the equatorial site of ODP Hole

959A.

157

Fig. 5. Photomicrographs no 1 of dinoflagellate cysts. A. Achomosphaera grallaeformis. Uncertain view, mid focus, S22, EF H12/3. B. Batiacasphaera spp. Uncertain view, mid focus, S22, EF J36-4. C. Batiacasphaera hirsuta. Uncertain view, high focus, S30, EF D32/3. D. Brigantedinium? spp., Left lateral view, low focus, S17, EF L30/1. E. Cerebrocysta bartonensis. Right lateral-dorsal view, high focus, S9, EF P39. F. Cerebrocysta? namocensis. Ventral view, high focus, S8, EF U44. G-H. Chiropteridium galea. G. Ventral view, high focus, S21, M19. H. Ventral view, low focus, S1, EF X11/1. I. Cordosphaeridium cantharellus. Dorsal view, high focus, S30, EF J18/4. J. Cribroperidinium giuseppei. Dorsal view, low focus, S2, EF M35/3. K. Cribroperidinium tenuitabulatum. Left lateral-ventral view, mid focus, S10, EF J11. L. Dapsilidinium pseudocolligerum. Apical view, mid focus, S30, EF N32/1.

158

Fig. 6. Photomicrographs no 2 of dinoflagellate cysts. A. Distatodinium ellipticum. Uncertain view, mid focus, S30, EF V26/4. B. Exochosphaeridium insigne. Dorsal view, mid focus, S3, EF L32/2. C-D. Habibacysta tectata. C. Dorsal view, low focus, S10, EF T9/1. D. Ventral view, mid focus, S10, EF T9/1. E-G. Hemiplacophora semilunifera. E. Ventral view, mid focus, S30, F30/3. F. Dorsal view, mid focus, S30, P37. G. Opercular piece or fragment of a specimen, mid focus, S30, EF Q38/4. H. Heteraulacacysta campanula. Uncertain view, mid focus, S17, EF E37/4. I. Homotryblium plectilum. Uncertain view, low focus, S28, EF F16/1. J-K. Homotryblium tenuispinosum. J. Apical view, low focus, S15, EF N43/3. K. Antapical view, high focus, S15, EF N43/3. L-M. Homotryblium vallum. L. Uncertain view, mid focus, S28, EF S23/1. M. Uncertain view, high focus, S28, EF S23/1.

159

Fig. 7. Photomicrographs no 3 of dinoflagellate cysts. A. Hystrichokolpoma cinctum. Uncertain view, mid focus, S26, EF J26/2. B. Hystrichokolpoma pusillum. Uncertain view, high focus, S29, EF L31/1. C. Kallosphaeridium biornatum. Ventral view, mid focus, S24, EF U40/1. D. Kallosphaeridium capulatum. Uncertain view, mid focus, S16, EF L36. E. Lejeunecysta hyalina. Dorsal view, mid focus, S16, EF J32/2. F-G. Lejeunecysta cinctoria. F. Dorsal view, high focus, S16, EF J41/2. G. Ventral view, low focus, S16, EF J41/2. H. Lejeunecysta communis. Dorsal view, mid focus, S19, EF M14/2. I. Lejeunecysta fallax. Uncertain view, mid focus, S9, EF F27. J. Lejeunecysta globosa. Dorsal view, mid focus, S16, EF R43/3. K-L. Lingulodinium machaerophorum. K. Uncertain view, low focus, S26, EF J9/3. L. Uncertain view, high focus, S4, EF F19/1.

160

Fig. 8. Photomicrographs no 4 of dinoflagellate cysts. A-B. Lingulodinium pycnospinosum. A. Uncertain view, high focus, S16, EF K26/1. B. Right lateral view, mid focus, S16, EF L27/4. C-D. Membranilarnacia? picena. C. Uncertain view, mid focus, S4, EF M12. D. Antapical view, high focus, S4, EF F21/1. E-F. Pentadinium laticinctum. E. Dorsal view, high focus, S23, EF V33/2. F. Dorsal view, mid focus, S23, EF R34/3. G-H. Nematosphaeropsis labyrinthus. G. Uncertain view, low focus, S22, EF Q28/2. H. Dorsal view, mid focus, S14, EF J32. I-J. Nematosphaeropsis lemniscata. I. Right lateral-ventral view, low focus, S4, EF H42. J. Left lateral-dorsal view, mid focus, S22, EF H24/1. K. Operculodinium piaseckii. Ventral view, mid focus, S22, EF O35/1. L. Polysphaeridium congregatum. Uncertain view, mid focus, S20, EF H28/3.

161

Fig. 9. Photomicrographs no 5 of dinoflagellate cysts. A-B. Polysphaeridium zoharyi. A. Apical view, mid focus, S17, EF F32/3. B. Apical view, low focus, S15, EF E36/4. C. Pyxidinopsis fairhavenensis. Dorsal view, mid focus, S10, EF D27/1. D. Reticulatosphaera actinocoronata. Uncertain view, high focus, S4, EF K12/1. E-F. Schematophora speciosa. E. Ventral view, mid focus, S30, W50/1. F. Ventral view, high focus, S30, W50/1. G. Selenopemphix armata. Apical view, low focus, S17, EF G34. H. Selenopemphix nephroides. Apical view, mid focus, S29, EF R31. I. Spiniferites mirabilis. Uncertain view, mid focus, S1, EF T38/3. J. Spiniferites pseudofurcatus. Left lateral-dorsal view, mid focus, S16, EF Q40. K. Thalassiphora succincta. Uncertain view, mid focus, S17, EF M34/1. L. Tuberculodinium vancampoae. Apical view, high focus, S16, EF O36/1.

162

6. CONCLUSIONS

(1) Six dinoflagellate cyst (sub)zones are defined. Zone 1 to zone 5 are interval zones

marked by the first occurrence or last occurrence of marker species, and subzones

1a and 1b are assemblage subzones. The biozones are dated as follow: subzone 1a,

Late Eocene (Priabonian); subzone 1b, Early Oligocene (Rupelian); zone 2, Late

Oligocene (Chattian); zone 3, earliest Early Miocene (early Aquitanian); zone 4,

Early Miocene (Aquitanian) to latest Early Miocene (early Burdigalian), and zone

5, latest Early Miocene (Burdigalian).

(2) A hiatus is observed in the Early Miocene within zone 3 and is identified by the

LOs of several dinoflagellate cysts. Palynological analysis proved to be the best

tool to observe this hiatus due to the absence of calcareous nannoplankton and

planktonic foraminifera in this part of the interval.

(3) A Priabonian age is proposed for subunit IIB, which was previously assigned a

middle Rupelian age. The presence of Hemiplacophora semilunifera and

Schematophora speciosa with other Late Eocene dinoflagellate cysts supports this

age assignment.

(4) The stratigraphic ranges of two of the recorded dinoflagellate cyst taxa in ODP

Hole 959A are different from those recorded at other locations in mid and high

latitudes, as well as equatorial regions. This disparity may be due to the deep

offshore depositional environment of ODP Hole 959A and/or latitudinal

differences. These ranges are discussed below:

163

(a) Cerebrocysta bartonensis has a younger LO in the present study (late

Aquitanian-early Burdigalian) than its previous record (Priabonian-early

Rupelian) in mid-high latitude regions.

(b) Chiropteridium galea extends to the Burdigalian in ODP Hole 959A, which

was previously assigned a LO of late Chattian in equatorial regions and middle

Aquitanian in Northern Hemisphere mid-latitudes.

ACKNOWLEDGMENTS

We would like to acknowledge the Department of Geosciences and Geological and

Petroleum Engineering, Missouri University of Science and Technology for funding this study. We would like to thank Dr. Javier Helenes, an anonymous reviewer and the journal editor Prof. Mohamed Abdelsalam for the detailed comments and useful suggestions that improved the manuscript.

164

APPENDIX A.

QUANTITATIVE DINOFLAGELLATE CYST DATA FOR HOLE 959A

165

Depth (mbsf) 193.25 200.5 209.1 213.77 218.72 223.55 231.66 235.24 239.87 244.61 255.98 262.69 270.81 274.23 283.86

Samples S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 Achomosphaera spp. 0 0 0 8 0 0 0 0 0 0 0 1 0 0 0 Achomosphaera 2 0 1 9 0 0 0 0 0 0 0 0 0 0 0 grallaeformis Batiacasphaera spp. 10 9 70 4 9 11 6 169 6 34 7 0 4 84 121 Batiacasphaera hirsuta 0 0 0 0 0 0 0 8 0 0 0 0 0 0 0 Bitectatodinium spp. 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Bitectatodinium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 tepikiense Brown cyst 0 0 0 0 0 0 0 0 2 0 0 0 0 2 0 Brigantedinium? spp. 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 Caligodinium sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Cerebrocysta spp. 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 Cerebrocysta sp A 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 Cerebrocysta 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 bartonensis Cerebrocysta? 0 0 0 3 4 13 0 112 2 4 0 0 0 0 13 namocensis Cerebrocysta 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 mediterranea Chiropteridium galea 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Cleistosphaeridium spp. 0 0 1 1 0 9 0 0 0 1 0 6 0 4 0 Cleistosphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 ancyreum C. diversispinosum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Cordosphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 cantharellus Cribroperidinium 0 167 0 0 0 0 0 0 0 1 0 0 0 0 0 giuseppei Cribroperidinium 0 10 0 0 0 0 0 0 0 1 0 0 0 0 0 tenuitabulatum Dapsilidinium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pseudocolligerum Distatodinium ellipticum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Eocladopyxis furculum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Exochosphaeridium 0 0 4 0 0 1 1 0 1 0 0 0 0 0 0 insigne Filisphaera spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 Filisphaera filifera 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Habibacysta tectata 0 0 0 0 0 0 0 0 0 2 1 0 1 3 2 Hafniasphaera spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Hafniasphaera delicata 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Hemiplacophora 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 semilunifera Heteraulacacysta 0 0 0 0 0 0 0 0 0 0 0 1 0 31 0 campanula Homotryblium plectilum 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 Homotryblium 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 tenuispinosum Homotryblium vallum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Hystrichokolpoma spp. 0 0 0 0 0 4 0 0 3 0 0 0 0 0 0 Hystrichokolpoma 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 cinctum Hystrichokolpoma 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pusillum Hystrichokolpoma 11 3 2 28 0 9 4 0 1 1 0 59 2 2 0 rigaudiae Impagidinium spp. 3 1 0 0 1 2 0 0 0 0 0 0 0 0 0 Impletosphaeridium spp. 0 0 0 3 0 1 0 0 0 0 11 0 0 1 0 Kallosphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 biornatum Kallosphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 capulatum Lejeunecysta spp. 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 Lejeunecysta communis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Lejeunecysta cinctoria 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Lejeunecysta globosa 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 Lejeunecysta fallax 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Lejeunecysta hyalina 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

166

Lingulodinium spp. 3 0 0 0 0 0 0 1 0 4 0 0 0 1 2 Lingulodinium 0 1 2 35 2 10 57 0 13 3 2 2 0 1 2 machaerophorum Lingulodinium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pycnospinosum Membranilarnacia? 0 0 0 29 0 0 0 0 0 0 0 0 0 0 0 picena Pentadinium laticinctum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Nematosphaeropsis spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Nematosphaeropsis 6 1 7 1 0 0 0 0 10 0 0 3 0 1 3 labyrinthus Nematosphaeropsis 15 0 0 2 0 0 0 0 0 0 0 0 0 0 2 lemniscata Operculodinium spp. 5 1 1 10 0 10 10 1 3 0 2 3 0 22 0 Operculodinium 0 3 0 0 0 0 0 0 0 0 1 0 2 0 12 centrocarpum Operculodinium 0 0 0 0 0 1 32 0 1 0 0 0 1 0 0 piaseckii Palaeocystodinium spp. 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Polysphaeridium spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Polysphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 congregatum Polysphaeridium 161 0 125 3 1 30 48 0 17 3 2 61 6 94 89 zoharyi Pyxidinopsis spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 Pyxidinopsis 0 0 0 0 0 0 0 0 0 2 0 0 0 0 6 fairhavenensis Reticulatosphaera 0 0 0 3 0 0 0 1 0 0 0 0 0 0 0 actinocoronata Schematophora speciosa 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Selenopemphix spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Selenopemphix armata 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Selenopemphix crenata 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 Selenopemphix 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 nephroides Senoniasphaera spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Spiniferites spp. 13 22 13 126 43 77 76 1 111 6 10 20 2 47 13 Spiniferites 0 0 0 3 0 1 0 1 0 0 0 0 1 1 1 pseudofurcatus Spiniferites mirabilis 0 0 0 9 0 3 2 1 1 0 0 0 0 3 0 Tectatodinium pellitum 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 Thalassiphora spp. 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 Thalassiphora succincta 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Trinovantedinium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pallidifulvum Tuberculodinium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 vancampoae Unidentified cysts 3 3 20 27 0 18 23 3 4 5 0 11 0 12 4

Total Counted 242 221 246 307 62 200 260 299 178 68 38 168 19 315 281

167

Depth (mbsf) 290.14 293.81 297.95 305.93 311.20 317.94 343.58 388.81 394.08 399.25 411.77 421.32 433.33 439.45 466.45

Samples S16 S17 S18 S19 S20 S21 S22 S23 S24 S25 S26 S27 S28 S29 S30 Achomosphaera 0 0 0 0 0 12 9 1 0 1 0 0 0 0 10 spp. Achomosphaera 0 0 0 0 1 5 16 13 6 0 0 0 0 0 0 grallaeformis Batiacasphaera 10 13 7 9 5 3 63 27 11 0 1 3 4 9 3 spp. Batiacasphaera 9 4 1 1 90 1 0 0 0 2 5 0 3 0 23 hirsuta Bitectatodinium 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 spp. Bitectatodinium 0 0 0 0 0 0 0 0 0 0 0 0 11 0 0 tepikiense Brown cyst 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Brigantedinium? 7 1 0 0 0 0 0 0 1 0 0 0 0 0 0 spp. Caligodinium sp. 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 Cerebrocysta spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Cerebrocysta sp A 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Cerebrocysta 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 bartonensis Cerebrocysta? 1 0 0 0 0 0 23 1 3 0 1 0 0 0 0 namocensis Cerebrocysta 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 mediterranea Chiropteridium 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 galea Cleistosphaeridium 0 6 0 0 0 0 0 0 2 0 0 0 1 0 0 spp. Cleistosphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ancyreum C. diversispinosum 0 0 0 0 0 0 0 0 0 0 0 0 0 7 0 Cordosphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 cantharellus Cribroperidinium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 giuseppei Cribroperidinium 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 tenuitabulatum Dapsilidinium 1 0 0 0 0 0 0 0 0 0 0 0 0 0 6 pseudocolligerum Distatodinium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 ellipticum Eocladopyxis 0 0 0 0 0 0 0 0 0 0 9 0 0 0 0 furculum Exochosphaeridium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 insigne Filisphaera spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Filisphaera filifera 0 0 0 0 0 0 0 0 0 0 0 0 47 96 3 Habibacysta tectata 1 3 1 0 2 0 0 5 0 0 0 0 0 0 0 Hafniasphaera spp. 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 Hafniasphaera 0 0 0 0 0 0 0 0 0 0 0 1 4 0 0 delicata Hemiplacophora 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 semilunifera Heteraulacacysta 44 17 0 0 11 0 0 0 0 0 0 0 0 0 0 campanula Homotryblium 0 0 0 0 1 0 0 0 0 1 0 0 155 3 1 plectilum Homotryblium 1 3 0 0 0 0 0 0 0 0 0 0 1 0 0 tenuispinosum Homotryblium 0 0 0 0 0 0 0 0 0 0 0 0 10 0 0 vallum Hystrichokolpoma 0 0 0 0 0 0 0 0 0 0 0 0 0 7 1 spp. Hystrichokolpoma 0 0 0 0 0 0 0 0 0 0 1 0 2 0 0 cinctum Hystrichokolpoma 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 pusillum

168

Hystrichokolpoma 0 1 0 0 0 0 0 0 0 0 3 0 0 81 1 rigaudiae Impagidinium spp. 1 0 0 0 0 0 1 0 1 1 1 0 0 1 0 Impletosphaeridium 0 0 0 0 3 0 3 1 17 5 6 3 1 1 16 spp. Kallosphaeridium 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 biornatum Kallosphaeridium 2 0 0 0 0 0 3 0 0 0 0 0 0 0 0 capulatum Lejeunecysta spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 Lejeunecysta 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 communis Lejeunecysta 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 cinctoria Lejeunecysta 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 globosa Lejeunecysta fallax 0 0 0 0 3 0 0 0 0 0 0 0 0 1 0 Lejeunecysta 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 hyalina Lingulodinium spp. 15 0 1 0 0 0 4 0 0 0 0 0 0 2 1 Lingulodinium 48 0 0 0 1 0 0 0 4 2 2 1 0 0 1 machaerophorum Lingulodinium 19 10 2 0 0 0 0 0 0 0 0 0 0 0 0 pycnospinosum Membranilarnacia? 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0 picena Pentadinium 0 0 0 0 0 1 0 8 0 0 0 0 0 0 0 laticinctum Nematosphaeropsis 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 spp. Nematosphaeropsis 0 12 0 0 2 2 4 0 0 0 0 0 0 0 0 labyrinthus Nematosphaeropsis 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 lemniscata Operculodinium 31 13 2 0 3 0 5 0 0 0 7 0 2 2 19 spp. Operculodinium 0 0 0 0 0 0 16 93 6 21 0 66 4 23 0 centrocarpum Operculodinium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 piaseckii Palaeocystodinium 0 0 0 0 0 0 0 1 0 1 0 1 0 0 0 spp. Polysphaeridium 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 spp. Polysphaeridium 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 congregatum Polysphaeridium 18 160 282 0 61 246 10 41 5 1 3 0 0 0 2 zoharyi Pyxidinopsis spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Pyxidinopsis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 fairhavenensis Reticulatosphaera 0 0 0 0 0 0 0 0 0 5 0 0 0 0 7 actinocoronata Schematophora 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 speciosa Selenopemphix spp. 0 2 0 0 0 0 0 1 0 0 0 0 0 0 0 Selenopemphix 0 4 0 0 0 0 0 1 0 0 4 0 0 0 0 armata Selenopemphix 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 crenata Selenopemphix 6 1 0 0 0 0 0 0 0 0 2 0 0 2 1 nephroides Senoniasphaera 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 spp. Spiniferites spp. 44 63 10 20 112 23 86 11 39 18 20 13 7 27 99 Spiniferites 55 0 0 0 2 3 0 1 4 6 1 40 0 1 0 pseudofurcatus Spiniferites 4 15 0 0 6 0 1 1 0 0 1 0 0 0 0 mirabilis Tectatodinium 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pellitum

169

Thalassiphora spp. 0 0 0 2 0 0 5 0 0 1 1 1 1 0 0 Thalassiphora 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 succincta Trinovantedinium 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 pallidifulvum Tuberculodinium 7 0 0 0 0 0 0 0 1 0 0 0 0 0 0 vancampoae Unidentified cysts 10 6 7 1 16 8 30 16 2 15 7 4 2 32 12

Total Counted 343 335 313 34 327 305 291 222 102 83 75 133 256 297 230

170

APPENDIX B.

LIST OF DINOFLAGELLATE CYST TAXA

171

Achomosphaera spp.

Achomosphaera grallaeformis (Brosius, 1963) Davey and Williams, 1969

Batiacasphaera spp.

Batiacasphaera hirsuta Stover, 1977

Bitectatodinium spp.

Bitectatodinium tepikiense Wilson, 1973

Brown cyst Soliman et al., 2012

Brigantedinium? spp.

Caligodinium sp.

Cerebrocysta spp.

Cerebrocysta sp A

Cerebrocysta bartonensis Bujak et al., 1980

Cerebrocysta? namocensis Head et al., 1989b

Cerebrocysta mediterranea Biffi and Manum, 1988

Chiropteridium galea (Maier, 1959) Sarjeant, 1983

Cleistosphaeridium spp.

Cleistosphaeridium ancyreum (Cookson and Eisenack, 1965a) Eaton et al., 2001

Cleistosphaeridium diversispinosum Davey et al., 1966

Cordosphaeridium cantharellus (Brosius, 1963) Gocht, 1969

Cribroperidinium giuseppei (Morgenroth, 1966a) Helenes, 1984

Cribroperidinium tenuitabulatum (Gerlach, 1961) Helenes, 1984

Dapsilidinium pseudocolligerum (Stover, 1977) Bujak et al., 1980

Distatodinium ellipticum (Cookson, 1965a) Eaton, 1976

172

Eocladopyxis furculum Awad and Oboh-Ikuenobe, 2016

Exochosphaeridium insigne de Verteuil and Norris, 1996a

Filisphaera spp.

Filisphaera filifera Bujak, 1984

Habibacysta tectata Head et al., 1989b

Hafniasphaera spp.

Hafniasphaera delicata Fensome et al., 2009

Hemiplacophora semilunifera Cookson and Eisenack, 1965a

Heteraulacacysta campanula Drugg and Loeblich Jr., 1967

Homotryblium plectilum Drugg and Loeblich Jr., 1967

Homotryblium tenuispinosum Davey and Williams, 1966b

Homotryblium vallum Stover, 1977

Hystrichokolpoma spp.

Hystrichokolpoma cinctum Klumpp, 1953

Hystrichokolpoma pusillum Biffi and Manum, 1988

Hystrichokolpoma rigaudiae Deflandre and Cookson, 1955

Impagidinium spp.

Impletosphaeridium spp.

Kallosphaeridium biornatum Stover, 1977

Kallosphaeridium capulatum Stover, 1977

Lejeunecysta spp.

Lejeunecysta communis Biffi and Grignani, 1983

Lejeunecysta cinctoria (Bujak et al., 1980) Lentin and Williams, 1981

173

Lejeunecysta globosa Biffi and Grignani, 1983

Lejeunecysta fallax (Morgenroth, 1966b) Artzner and Dörhöfer, 1978

Lejeunecysta hyalina (Gerlach, 1961) Artzner and Dörhöfer, 1978

Lingulodinium spp.

Lingulodinium machaerophorum (Deflandre and Cookson, 1955) Wall, 1967

Lingulodinium pycnospinosum (Benedek, 1972) Stover and Evitt, 1978

Membranilarnacia picena Biffi and Manum, 1988

Nematosphaeropsis spp.

Nematosphaeropsis labyrinthus (Ostenfeld, 1903) Reid, 1974

Nematosphaeropsis lemniscata Bujak, 1984

Operculodinium spp.

Operculodinium centrocarpum (Deflandre and Cookson, 1955) Wall, 1967

Operculodinium piaseckii Strauss and Lund, 1992

Palaeocystodinium spp.

Pentadinium laticinctum Gerlach, 1961

Polysphaeridium spp.

Polysphaeridium congregatum (Stover, 1977) Bujak et al., 1980

Polysphaeridium zoharyi (Rossignol, 1962) Bujak et al., 1980

Pyxidinopsis spp.

Pyxidinopsis fairhavenensis de Verteuil and Norris, 1996a

Reticulatosphaera actinocoronata (Benedek, 1972) Bujak and Matsuoka, 1986

Schematophora speciosa Deflandre and Cookson, 1955

Selenopemphix spp.

174

Selenopemphix armata Bujak et al., 1980

Selenopemphix crenata Matsuoka and Bujak, 1988

Selenopemphix nephroides Benedek, 1972

Senoniasphaera spp.

Spiniferites spp.

Spiniferites pseudofurcatus (Klumpp, 1953) Sarjeant, 1970

Spiniferites mirabilis (Rossignol, 1964) Sarjeant, 1970

Tectatodinium pellitum Wall, 1967

Thalassiphora spp.

Thalassiphora succincta Morgenroth, 1966b

Trinovantedinium pallidifulvum Matsuoka, 1987

Tuberculodinium vancampoae (Rossignol, 1962) Wall, 1967

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IV. PALEOGENE-EARLY NEOGENE PALEOENVIRONMENT AND PALEOCLIMATE RECONSTRUCTION BASED ON PALYNOLOGICAL ANALYSIS OF ODP HOLE 959A, WEST AFRICA

Walaa K. Awad, Francisca E. Oboh-Ikuenobe

Geology and Geophysics Program, Department of Geosciences and Geological and

Petroleum Engineering, Missouri University of Science and Technology, 129 McNutt

Hall, Rolla, MO 65409-0410, USA

ABSTRACT

Five paleoenvironmental intervals (interval 1-interval 5) are established in the late

Paleogene-early Neogene of the Ocean Drilling Program (ODP) Site 959 (Hole 959A),

Côte d’Ivoire-Ghana Transform Margin in the eastern Equatorial Atlantic. The intervals are based on detailed dinoflagellate cyst and palynofacies analyses of 30 samples covering a 273.3-m interval. We observed an abundance of the Filisphaera group (Filisphaera filifera and Bitectatodinium tepikiense) which may be indicative of an arctic migration to equatorial regions during a narrow interval in the Early Oligocene (early Rupelian). In addition, we document one hiatus event within interval 3 in the Early Miocene

(Aquitanian). The superabundances of typically restricted marine species of the

Polysphaeridium group (Homotryblium plectilum and Polysphaeridium zoharyi) in the open-oceanic sediments of ODP Hole 959A are considered very distinctive bioevents.

Upon integrating dinoflagellate cyst data with prior lithologic and microfossil data, we interpret these superabundance events as possibly due to offshore transportation by turbidity currents (intervals 1 and 2), hiatus event (interval 3), or hyperstratification

183 conditions (intervals 3 and 4). In addition, the superabundance of Cribroperidinium spp.

(C. giuseppei and C. tenuitabulatum) in the upper part of the section within paleoenvironmental interval 5 is suggestive of cold water masses during a strong upwelling period in the latest Early Miocene (Burdigalian). The general abundance of amorphous organic matter alongside the dinoflagellate cyst compositions supports an outer neritic- oceanic depositional environment for the studied site. The consistent occurrence of degraded phytoclasts in the sediments also suggests fluvial outflows to this offshore site.

Keywords: Dinoflagellate cysts; late Paleogene-early Neogene; paleoenvironment; paleoclimate; palynofacies; eastern Equatorial Atlantic.

1. INTRODUCTION

The Paleogene-early Neogene is a highly dynamic period that was accompanied by rapid climatic changes from the greenhouse of the Paleocene-Eocene Thermal Maximum

(PETM) to icehouse conditions in the Oligocene (Zachos et al., 2001). Several studies using multiproxies have proved that the Paleocene-Eocene climate was the warmest during this time (Zachos et al., 2008) and was marked by a rise in the temperature of the deep ocean and high latitude oceanic surface water. This warm climate resulted in either major extinction events (e.g., benthic foraminifera) or a great turnover and flourishing for other organisms (e.g., mammals and plants) (Crouch et al., 2003; Sluijs et al., 2007). The Earth’s transformation from a greenhouse to an icehouse state lasted from the Middle-Late Eocene to the Early Oligocene. This change was believed to be gradual for a long time; however, multiple proxies have shown that several extreme transient climatic events occurred

184 throughout this time (Pross and Brinkhuis, 2005; Sluijs et al., 2005). The cooling started to shift in the Late Oligocene to another warm trend that was recorded during the Middle

Miocene Climate Transition (MMCT), which resulted in the warmest temperatures since the PETM (Shevenell et al, 2004; Zachos et al., 2008; Schreck et al., 2013).

Palynomorphs are very sensitive to any changes in provenance, sedimentation processes and prevailing climate, making palynology an important tool for inferring paleonvironmental conditions (Pross and Brinkhuis, 2005; Sluijs et al., 2005; Traverse,

2007). Because the main source of pollen and spores is the land, they can reflect the paleoclimate of the surrounding continents (Traverse, 2007), whereas dinoflagellates are mainly marine, although they can live in fresh water (Fensome et al., 1996; Bujak and

Brinkhuis, 1998; Sluijs et al., 2005). Dinoflagellates are abundant in neritic settings, as opposed to many other microfossil groups that are mainly restricted to the offshore, such as planktonic foraminifera, diatom and Radiolaria (Sluijs et al., 2005). Extant dinoflagellates are very sensitive to any changes in the sea surface temperature, salinity, proximal-distal signals, and even minor changes in nutrient availability (e.g., Sluijs et al.,

2005). Therefore, their cysts can be used for reconstructing paleoclimate, paleoenvironment, paleosalinity, and paleoproductivity, but such studies must consider factors that can affect their preservation in sediments (Pross and Brinkhuis, 2005; Sluijs et al., 2005). These factors include sea surface temperature, sea surface salinity, transportation, migration, oxidation, mechanical degradation, maturation, freshwater runoff, and upwelling.

This paper presents results of a palynological study of on 30 samples (S1-S30,

193.25-466.45 mbsf) from the Late Eocene to the Early Miocene interval in ODP Hole

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959A in the Côte d’Ivoire-Ghana Transform Margin, West Africa (Fig. 1). Shipboard

Scientific Party (1996), Shafik et al. (1998a, 1998b) and Awad and Oboh-Ikuenobe (2018) studied this interval for detailed biostratigraphic analyses (Figs. 2 and 3). Additionally,

Oboh-Ikuenobe et al. (1997, 1999) focused on the palynofacies analysis of the same interval to understand the depositional environment, paleobathymetry of the basin, and thermal evolution of the sediments. The aim of the present study is to integrate detailed dinoflagellate cyst analysis with lithology (texture, composition) and palynofacies

(particulate organic matter) to achieve a better understanding of the paleoenvironmental and paleoclimatic conditions.

Fig. 1. Map showing the location of ODO Hole 959A in the Côte d’Ivoire-Ghana Transform Margin in the eastern Equatorial Atlantic, West Africa.

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2. GEOLOGIC SETTING

ODP Leg 159 drilled four sites (959-962) on the Côte d’Ivoire-Ghana Transform

Margin in the eastern Equatorial Atlantic, West Africa (January-February 1995). Site 959

(959A, 959B, 959C, 959D) has the most complete stratigraphic sequence with a maximum penetration in Hole 959D at 1158.9 meter below sea floor (mbsf), followed by a 480.7 mbsf in Hole 959A, 184.4 mbsf in Hole 959B and 179.6 in Hole 959C. Detailed information on the tectonics and lithology are described in the following sections.

2.1. TECTONICS

The Côte d’Ivoire-Ghana Transform Margin was initiated possibly during the Late

Jurassic by the onset of the rifting between Africa and South America and subsequent extensive depositional processes during the Neocomian (Benkheil et al., 1998; Pickett and

Allerton, 1998). The northeast-southwest trending transform margin consists mainly of a northern border known as the Deep Ivorian Basin and a southern border, the Côte d’Ivoire-

Ghana Margin Ridge (CIGMR) (Shipboard Scientific Party, 1996; Pickett and Allerton,

1998). Shipboard Scientific Party (1996) proposed four tectonic stages to describe the early evolution of the CIGMR.

During the early rifting stage (Early Cretaceous), several grabens and pull-apart basins were initiated and filled by thick intracontinental sediments indicative of lacustrine and deltaic depositional systems. Structural data reflect sedimentary instability due to the active tectonic processes during this time (Shipboard Scientific Party, 1996; Benkheil et al., 1998). Africa and South America were still partially connected at this stage.

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The two continents broke up completely during the syntransform stage (Aptian-

Albian), forming a wrenching zone along the southern border of the Deep Ivorian Basin and the oceanic crust. Due to the intensive motions at this stage, the sedimentary sequences reflected major disturbances indicated by the uplift of the CIGMR and unconformity at all four ODP sites.

The end of the syntransform stage (latest Albian-Cenomanian) was marked by continued uplift of the CIGMR resulting from the contact between the hot oceanic lithosphere and cold continental crust. This uplift led to an intensive deformation of the top of the CIGMR by flower structures and shearing during the Cenomanian.

The passive margin stage (post-Cenomanian) experienced very little tectonic activities. Carbonate sediments dominated the Late Cretaceous interval above the eroded ridge and the deposition of sediments became more stable during the Paleogene period with more pelagic sedimentation. Some extensional structures affected the Cenozoic sediments, and strong submarine erosions represented by canyons and wide submarine valleys occurred during major sea level lowstands.

2.2. LITHOSTRATIGRAPHY

Shipboard Scientific Party (1996) divided the sedimentary succession into five lithological units (I to V downsection; Fig. 2). Some of the units have been further divided into subunits based on lithology and/or diagenesis. Unit I (Holocene to Early Miocene, 208 m) is divided into two subunits (IA and IB) comprising nannofossil ooze and foraminifera ooze transitioning downhole to chalk. The subunits are also characterized by alternation from darker to lighter color and increasing clay content downhole, and their boundary is

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Fig. 2. Schematic stratigraphic column for ODP site 959. lithological description of (sub)units I to V are shown to the right (modified from Shipboard Scientific Party, 1996).

gradational due mainly to bioturbation. Unit II (Early Miocene to Late Paleocene, 599.3 m) has three subunits composed of siliceous phases and their diagenetic sediments as follows: diatomite (IIA), chert (IIB) and porcellanite (IIC). The siliceous components

(diatoms, radiolarians, spicules and silicoflagellates) average 40% and reach up to 90% of the pelagic grains of subunit IIA. The predominantly deep bathyal trace fossil assemblage and abundance of pelagic and hemipelagic sediments suggest an offshore depositional site that experienced high productivity due to upwelling of the nutrient-rich ocean water and/or

189 influx of phosphates and nitrates through fluvial systems (Shipboard Scientific Party, 1996;

Oboh-Ikuenobe et al., 1997).

Unit III (Late Paleocene to early Coniacian, 231 m) consists mainly of black claystone with deep water trace fossils and authigenic minerals, such as barite, pyrite, and glauconite. Three phosphatic hardgrounds with black and brown nodules are noticed at many levels at the basal part of this interval and reflect either unconformities or condensed horizons during the late Coniacian to late Santonian (Oboh-Ikuenobe et al., 1997; Strand,

1998). Unit IV (early Coniacian to early Turonian and older, 38.4 m) comprises quartz- sand-rich limestone and dolomite, and is divided into subunits IVA and IVB based on lithological differences (e.g., quartz content) and sedimentary structures such as the types of bedding. This unit has coarser clastic rocks than the younger units, which reflects a high energy, nearshore environment. Furthermore, the co-occurrence of carbonate reef and siliciclastic sediments marks the maximum uplift of the ridge during this time (Shipboard

Scientific Party, 1996; Oboh-Ikuenobe et al., 1997; Strand, 1998). Unit V (late Albian, 77.2 m) was deposited in a deep-water lacustrine setting with thin, well sorted and laminated and cross-laminated sand beds (Shipboard Scientific Party, 1996; Pickett and Allerton,

1998; Hisada et al., 1998). Shallow marine shelf sediments overlie the rhythmic lacustrine sediments indicating by the hummocky cross-bedded sandstone (Strand, 1998).

3. MATERIALS AND METHODS

A total of 30 samples from ODP Hole 959A were examined for their palynological contents (Table 1 and Fig. 3). Standard palynological methods (Traverse, 2007) were used

190 to extract the organic fraction of the samples. In the present study, we followed the same procedure of Awad and Oboh-Ikuenobe (2016, 2018). A minimum of 300 dinoflagellate cysts was counted per slide, except for samples with poor yields, in order to estimate the relative abundance of each taxon. We also counted all the sporomorphs alongside the dinoflagellate cysts (Fig. 4; Table 2), although detailed analysis of pollen and spores was not attempted in this study. Additionally, 500 particles of particulate organic matter were point counted per slide in order to record variations in the proportions of terrestrial and marine components related to changes in the depositional site (Fig. 5). The particulate organic matter components are noted in Table 3 and are modified from Oboh-Ikuenobe et al. (2005). Estimates for the total dinoflagellate cysts and sporomorphs in the slides were converted to percentages and discussed as follows: rare (<1-5%), few (6-10%), common

(10-20%), abundant (20-40%) and superabundant (>40%). The systematic classification and nomenclature of dinoflagellate cysts follow Fensome et al. (2008) and Williams et al.

(2017), and descriptive terminology follows Evitt (1985) and Williams et al. (2000).

4. RESULTS AND DISCUSSION

Palynomorph preservation in the ODP Hole 959A samples is generally fair, and recovery varies from poor to good. Terrestrial palynomorphs (mostly pollen and spores) are present, but generally less abundant than dinoflagellate cysts. The top of the section of the studied interval has higher percentage of terrestrial palynomorphs than the middle and bottom sections (Fig. 4). Some taxa and/or groups of morphologically-related taxa typically represent 80-90% of the dinoflagellate cyst assemblage (Figs. 6-8, Table 4). Their

191 quantitative distribution (only in samples with >100 dinoflagellate cyst specimens) is shown in Figure 4. The Polysphaeridium group dominates the dinoflagellate cyst assemblages, reaching up to 85% of the assemblage in sample S18 (297.95 mbsf). In addition, Batiacasphaera spp., Operculodinium spp., and Spiniferites group are present in every sample (mostly higher than 5% and up to ⁓54%). In order to describe the studied interval in detail, we ran cluster analysis on the dinoflagellate cyst data set using Tilia software (Fig. 4). This constrained analysis has been used to divide the studied section into five intervals from the bottom to the top (Interval 1- interval 5).

Palynofacies analysis indicates a general abundance of amorphous organic matter; in addition to high percentages of degraded phytoclasts in some parts of the studied interval.

The high percentages of degraded phytoclasts are not necessarily indicative of a shallowing environment. Zobaa et al. (2015) and El Beialy et al. (2016) noted that offshore transportation of terrigenous components to deep depositional sites such as ODP Hole

959A often results in misleading paleoenvironmental interpretations using sedimentary particulate organic matter ternary diagrams. In this study, we have integrated palynofacies analysis with other proxies (lithology, trace fossils, dinoflagellate cysts, calcareous nannofossils) to infer how the POM components are represented in an offshore site that is subject to the deposition of enormous quantities of terrestrial components by transportation through turbidity currents.

4.1. INTERVAL 1 (PRIABONIAN-EARLY RUPELIAN, 466.45-433.33 MBSF)

Sample S30 (466.45 mbsf) records high percentages of the Spiniferites group

(43.4%), few to common occurrences of Batiacasphaera spp. (10.4%), Operculodinium

192 spp. (7.5%) and Impletosphaeridium spp. (6.4%), and rare occurrences of the Filisphaera group (1.2%), Hystrichokolpoma spp. (0.8%), Lejeunecysta group (0.4%), Lingulodinium spp. (0.8%), and Polysphaeridium group (1.2%). This same sample also records 8.4% of terrestrial palynomorphs. While extant species of Operculodinium spp. and the Spiniferites group are cosmopolitan and have been recorded from inner neritic to oceanic environments, their acme occurrence is more common in offshore settings due to transportation (Wall et al., 1977; Brinkhuis, 1994; Iakovleva, 2011, 2015; Awad and Oboh-Ikuenobe, 2016).

Fig. 3. Summary of the lithologic and biostratigraphic data for ODP Hole 959A.

193

Table 1. List of samples, Missouri University of Science and Technology Repository no. (showing slide no) and sample depths for ODP Hole 959A; mbsf = meter below sea floor.

Samples Repository No. Depth (mbsf)

S1 MST-1863-SL2 193.25

S2 MST-1864-SL2 200.50 S3 MST-1865-SL1, SL2 209.10 S4 MST-1866-SL2 213.77 S5 MST-1867-SL1, SL2 218.72 S6 MST-1868-SL1, SL2 223.55 S7 MST-1869-SL1, SL2 231.66 S8 MST-1870-SL2 235.24 S9 MST-1871-SL1, SL2 239.87 S10 MST-1872-SL1, SL2 244.61 S11 MST-1873-SL1, SL2 255.98 S12 MST-1874-SL1, SL2 262.69 S13 MST-1875-SL1, SL2 270.81 S14 MST-1876-SL1 274.23 S15 MST-1877-SL1, SL2 283.86 S16 MST-1878-SL1 290.14 S17 MST-1879-SL1 293.81 S18 MST-1880-SL1 297.95 S19 MST-1881-SL1, SL2 305.93 S20 MST-1882-SL1 311.20 S21 MST-1883-SL1, SL2 317.94 S22 MST-1884-SL1, SL2 343.58 S23 MST-1885-SL1, SL2 388.81 S24 MST-1886-SL1, SL2 394.08 S25 MST-1887-SL1, SL2 399.25 S26 MST-1888-SL1, SL2 411.77 S27 MST-1889-SL1, SL2 421.32 S28 MST-1890-SL1, SL2 433.33 S29 MST-1891-SL1, SL2 439.46 S30 MST-1892-SL1, SL2 466.45

194

Table 2. Raw count data for dinoflagellate cyst groups/species and sporomorphs (pollen

and spores).

44.61)

(mbsf)

and Depth

S2 (200.5) S3 (209.1)

S1 (193.25) S4 (213.77) S5 (218.72) S6 (223.55) S7 (231.77) S8 (235.24) S9 (239.87)

S10 (2 S10 (255.98) S11 (262.69) S12 (270.81) S13 (274.23) S14 (283.86) S15 Samples numbers numbers Samples

Batiacasphaera spp. 10 9 70 4 9 11 6 177 6 34 7 0 4 84 121 Bitectatodinium spp. 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Cerebrocysta spp. 0 0 0 5 4 13 0 112 3 4 1 0 0 0 13 Cleistosphaeridium spp. 0 0 1 1 0 9 0 0 0 1 0 6 0 4 4 Cribroperidinium spp. 0 177 0 0 0 0 0 0 0 2 0 0 0 0 0 Filisphaera spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 Habibacysta tectata 0 0 0 0 0 0 0 0 0 2 1 0 1 3 2 Heteraulacacysta 0 0 0 0 0 0 0 0 0 0 0 1 0 31 0 campanula Homotryblium spp. 0 0 0 0 0 0 0 0 0 0 0 1 0 1 1 Hystrichokolpoma spp. 11 3 2 28 0 13 4 0 4 1 0 59 2 3 0 Impagidinium spp. 3 1 0 0 1 2 0 0 0 0 0 0 0 0 0 Impletosphaeridium spp. 0 0 0 3 0 1 0 0 0 0 11 0 0 1 0 Lejeunecysta spp. 0 0 0 0 1 0 0 1 1 0 1 0 0 2 0 Lingulodinium spp. 3 1 2 35 2 10 57 1 13 7 2 2 0 2 4 Nematosphaeropsis spp. 21 1 7 3 0 0 0 0 10 0 0 3 0 1 5 Operculodinium spp. 5 4 1 10 0 11 42 1 4 0 3 3 3 22 12 Polysphaeridium group 161 0 125 3 1 30 48 0 17 3 2 61 6 94 89 Spiniferites group 15 22 14 155 43 81 78 3 112 6 10 21 3 51 14 Thalassiphora spp. 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 Other dinocysts 13 3 24 59 1 19 25 4 7 8 0 11 0 14 16 Terrestrial palynomorphs 42 145 33 81 20 76 45 75 29 216 10 16 9 66 47 Total 284 366 279 388 82 276 305 374 207 284 48 184 28 381 328 dinocyst+palynomorphs

195

Table 2. Raw count data for dinoflagellate cyst groups/species and sporomorphs (pollen

and spores) (Cont.)

Depth

(mbsf)

21 21 (317.94)

S20 (311.2) S20

S16 (290.14) S16 (293.81) S17 (297.95) S18 (305.93) S19 S (343.58) S22 (388.81) S23 (394.08) S24 (399.25) S25 (411.77) S26 (421.32) S27 (433.33) S28 (439.46) S29

S30 (4.66.45) S30 Samples numbers and numbers Samples

Batiacasphaera spp. 19 17 8 10 95 4 63 27 11 2 6 3 7 9 26 Bitectatodinium spp. 0 0 0 0 0 0 0 0 0 0 0 0 12 0 0 Cerebrocysta spp. 1 0 0 0 0 0 27 1 3 1 1 0 0 0 0 Cleistosphaeridium spp. 0 6 0 0 0 0 0 0 2 0 0 0 1 7 0 Cribroperidinium spp. 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 Filisphaera spp. 0 0 0 0 0 0 0 0 0 0 0 0 47 96 3 Habibacysta tectata 1 3 1 0 2 0 0 5 0 0 0 0 0 0 0 Heteraulacacysta 44 17 0 0 11 0 0 0 0 0 0 0 0 0 0 campanula Homotryblium spp. 1 3 0 0 1 0 0 0 0 1 0 0 166 3 1 Hystrichokolpoma spp. 0 1 0 0 0 0 0 0 0 0 4 0 2 89 2 Impagidinium spp. 1 0 0 0 0 0 1 0 1 1 1 0 0 1 0 Impletosphaeridium spp. 0 0 0 0 3 0 3 1 17 5 6 3 1 1 16 Lejeunecysta group. 11 7 0 1 4 0 0 2 0 0 6 0 0 4 1 Lingulodinium spp. 82 10 3 0 1 0 4 0 4 2 2 1 0 2 2 Nematosphaeropsis spp. 0 12 0 0 2 2 9 0 0 0 0 0 0 0 0 Operculodinium spp. 31 13 2 0 3 0 21 93 6 21 7 66 6 25 19 Polysphaeridium group 18 160 282 0 64 246 10 41 5 1 12 0 0 0 2 Spiniferites group 103 78 10 20 121 43 113 27 49 25 22 54 11 28 109 Thalassiphora spp. 0 1 0 2 0 0 5 0 0 1 1 1 1 0 0 Other dinocysts 31 7 7 1 20 10 34 25 4 23 7 5 2 32 49 Terrestrial palynomorphs 52 22 19 6 22 22 81 73 16 18 13 12 102 22 21 Total 395 357 332 40 349 327 372 295 118 101 88 145 358 319 251 dinocyst+palynomorphs

196

Table 3. Point count data for particulate organic matter components.

Samples Amorphous numbers and Marine Terrestrial Opaque Degraded Structured Fungal organic Cuticle Depth palynomorphs palynomorphs phytoclasts phytoclasts phytoclasts remains matter Total (mbsf)

S1(193.25) 21 0 284 8 174 2 0 11 500 S2(200.5) 31 11 203 7 201 6 4 37 500 S3(209.1) 16 4 417 3 56 2 0 2 500 S4(213.77) 15 4 290 20 154 11 3 3 500 S5(218.72) 18 1 406 2 71 0 0 2 500 S6(223.55) 13 3 368 9 103 2 0 2 500 S7(231.77) 38 2 371 2 85 1 0 1 500 S8(235.24) 28 4 234 6 219 4 2 3 500 S9(239.87) 33 7 294 5 150 5 2 4 500 S10(244.61) 27 6 309 7 138 5 1 8 500 S11(255.9 26 1 386 9 62 9 1 6 500 S12(262.69) 18 0 460 8 12 1 0 1 500 S13(270.81) 16 2 406 3 66 2 3 2 500 S14(274.23) 33 3 379 2 77 5 1 0 500 S15(283.86) 8 1 338 13 137 3 0 0 500 S16(290.14) 20 10 314 3 144 7 2 0 500 S17(293.81) 43 10 290 0 140 13 4 0 500 S18(297.95) 27 2 376 2 92 1 0 0 500 S19(305.93) 25 5 364 5 90 4 4 3 500 S20 (311.2) 44 1 322 13 107 9 4 0 500 S21(317.94) 23 1 357 3 97 15 0 4 500 S22(343.58) 18 3 386 2 73 17 0 1 500 S23(388.81) 15 2 424 3 46 8 0 2 500 S24(394.08) 4 1 334 43 104 8 0 6 500 S25(399.25) 2 3 392 16 63 10 0 14 500 S26(411.77) 6 3 395 40 47 1 0 8 500 S27(421.32) 8 2 428 25 34 0 0 3 500 S28(433.33) 6 1 405 21 65 0 0 2 500 S29(439.46) 9 0 423 14 50 3 0 1 500 S30(466.45) 7 2 361 10 116 2 0 2 500

Upsection in sample S29 (439.46 mbsf), there is a remarkable drop in the percentages of the Spiniferites group (8.8%), Batiacasphaera spp. (2.8%) and

Impletosphaeridium spp. (0.3%), but percentages of the following species do not differ much from sample S30: Lejeunecysta group (1.3%), Lingulodinium spp. (0.6%),

197

Operculodinium spp. (7.8%), and Polysphaeridium group (0.9%). Meanwhile, abundant occurrences are recorded for the Filisphaera group (mainly Filisphaera filifera and

Bitectatodinium tepikiense; 30%), and Hystrichokolpoma spp. (mainly H. rigaudiae;

27.9%). The abundances of F. filifera and B. tepikiense in the upper part of this interval are considered unique bioevents in the Early Oligocene (Rupelian) in this equatorial study site.

These very good stratigraphic marker species are generally found in the high latitude regions (Head 1994; 1996). However, their abundances in equatorial regions may be an indicator of cold water masses that were prevailing during this time (de Vernal and Mudie,

1989; De Schepper et al., 2009). The distribution of B. tepikiense today is closely related to the subpolar–temperate transition (Dale and Fjellså, 1994; Dale, 1996) and its abundance

(>10%) in assemblages usually occurs when summer sea surface temperatures are less than

⁓17°C (Edwards and Andrle, 1992; Marret and Zonneveld, 2003).

Thus, presence of these marker species in interval 1 in ODP Hole 959A may be indicative of an Arctic dinoflagellate migration to low latitude regions during a narrow time interval in the Rupelian. Furthermore, the abundance of the Filisphaera group and

Hystrichokolpoma spp., the appearance of Impagidinium in sample S29, and the low percentage of terrestrial palynomorphs (6.9%) confirms the offshore, outer neritic to oceanic environment of the site (e.g., Jaramillo and Oboh-Ikuenobe, 1999; Brinkhuis et al.,

2003a, 2003b; Gedl, 2005; Pross and Brinkhuis, 2005; Sluijs et al., 2005; Udeze and Oboh-

Ikuenobe, 2005; De Schepper et al., 2009; Gedl and Peryt, 2011; Iakovleva, 2011, 2015).

At the top of this interval in sample S28 (433.33 mbsf), a decrease in the percentages of most dinoflagellate cyst species occurs, except a superabundance of the Polysphaeridium group (mainly Homotryblium plectilum, 46.4%), and an abundance of terrestrial

198 palynomorphs (28.5%) are noted. Homotryblium is became extinct in the middle to the

Late Miocene and has no extant representatives in the modern ocean (Brinkhuis, 1994;

Williams et al., 2004). Its morphological and archaeopyle similarities to the extant species

Polysphaeridium zoharyi suggest similar latitudinal and environmental distributions

(Williams and Bujak, 1977; Edwards, 1986; Brinkhuis, 1994). Polysphaeridium is more common in coastal, tropical-subtropical regions characterized by warm water, restricted marine environment and high salinity (Zonneveld et al., 2013). However, the

Polysphaeridium group (Polysphaeridium and Homotryblium) has also been recorded in offshore sediments, such as the Atlantic shelf (Stover, 1977) and ODP Hole 959D (Awad and Oboh-Ikuenobe, 2016). While it is possible for cysts of the Polysphaeridium group to be transported from nearshore environments to offshore sites as reworked dinoflagellate cysts (Gedl, 2004), their abundance in offshore settings may also be due to hyperstratified conditions (Reichart et al., 2004). On the other hand, other studies suggest that

Homotryblium can be tolerant of a wide range of salinity (Crouch and Brinkhuis, 2005;

Sluijs et al., 2005; Bankole et al., 2007). Based on the aforementioned studies, the superabundance of Homotryblium in the upper part of interval 1 can be related to several possible factors in the offshore site ODP Hole 959A: (1) a change in the environment to more restricted conditions; (2) highly stratified conditions; (3) transportation from nearshore sites due to high turbidity currents or through submarine fluvial systems; (4) new record of this species in outer neritic to oceanic environments with normal salinity conditions. Shipboard Scientific Party (1996) indicated that bioturbation was slight high to moderate throughout Subunit IIA (diatomite), where S28 was subsampled. They also proposed a possible connection between the land and the offshore site through submarine

199 fluvial outflows due to the high percentage of plant particles throughout unit II. These evidences together with the presence of a deep bathyal trace fossil assemblage comprising

Zoophycos, Chondrites and Planolites (Fig. 2), and the high percentages of pollen and spores suggest that transportation offshore may be the most likely reason for the superabundance of Homotryblium spp. in this part of the interval.

Palynofacies analysis also supports deep marine depositional environment for interval 1 (Figs. 5 and 8), as indicated by the superabundance of AOM (72-84.6%) and common-abundant degraded phytoclasts (10-23%). While high percentages of AOM generally indicate increase in the productivity of the surface ocean water (Powell et al.

1992; Udeze and Oboh-Ikuenobe 2005; Oboh-Ikuenobe et al., 2012), they also form as a result of the degradation of algal matter and are generally recorded in reducing, low energy environments with high preservation potential (Oboh-Ikuenobe et al., 2005; Zobaa et al.,

2011a, 2013; El Beialy et al., 2016; Barron et al., 2017). Note that continentally derived particulate organic matter components (phytoclasts, sporomorphs, fungal remains) can be preserved in marginal and deep marine environments (Jaramillo and Oboh-Ikuenobe, 1999;

Oboh-Ikuenobe et al., 2012; Barron et al., 2017), and their distribution can be affected by such factors as increase in continental runoff, climate, tectonics, chemical composition of water, biological activity, etc. (Batten, 1996; Oboh-Ikuenobe et al., 2012).

4.2. INTERVAL 2 (MIDDLE RUPELIAN-LATE CHATTIAN, 421.32- 343.58 MBSF).

Operculodinium spp. (5.6-45.5%) and the Spiniferites group (9-41.5%) dominate the samples in this interval (Fig. 4). Rare to common occurrences are recorded for these dinoflagellate cysts: Batiacasphaera spp. (2-17%), Cerebrocysta spp. (0.3-7%),

200

Cleistosphaeridium spp. (1.7%), Cribroperidinium spp. (0.3%), Habibacysta tectata

(1.7%), Impagidinium spp. (0.3-1%), Impletosphaeridium spp. (0.8-14.4%), Lejeunecysta group (0.7%), Lingulodinium spp. (0.7-3.4%), Nematosphaeropsis spp. (2.4%),

Polysphaeridium group (2-13.9%), and Thalassiphora spp. (0.7-1%). The sporomorphs range from 8.3% to 24.7 % in this interval.

Superabundances of Spiniferites and Operculodinium are generally considered as indicators of an open marine environment (e.g., Brinkhuis and Zachariasse, 1988; Eshet et al., 1992; Edwards and Andrle, 1992; Brinkhuis, 1994; Dale, 1996; Slimani et al., 2010;

Iakovleva, 2011, 2015). Furthermore, the presence of Batiacasphaera, Cerebrocysta,

Habibacysta tectata, Impagidinium, Impletosphaeridium, Lingulodinium (mainly L. machaerophorum) Nematosphaeropsis and Thalassiphora (Fig. 4, Table 4) suggests an outer neritic-oceanic environment for the bottom of interval 2 (e.g., Brinkhuis and

Zachariasse; 1988, Powell et al., 1996; Jaramillo and Oboh-Ikuenobe, 1999; Gedl, 2005;

Pross and Brinkhuis,2005; Sluijs et al., 2005; Udeze and Oboh-Ikuenobe, 2005; Iakovleva,

2015; Awad and Oboh-Ikuenobe, 2016). The Lejeunecysta group (Lejeunecysta spp. and

Selenopemphix spp.) represents coastal and nearshore environments, tropical-subtropical conditions and high productivity periods (Brinkhuis et al., 1992; Sluijs et al., 2005; Gedl,

2005; Iakovleva, 2011, 2015). Therefore, their occurrence with oceanic environment taxa in in the bottom of interval 2, such as Batiacasphaera, Cerebrocysta, Impagidinium,

Nematosphaeropsis and Thalassiphora, may suggest a rich nutrient water discharge to the area of deposition or strong upwelling periods.

201

Table 4. Dinoflagellate cyst groups and their possible ecological interpretation.

Dinocyst complex Included taxa Ecological interpretation References

Batiacasphaera Batiacasphaera spp. Offshore Brinkhuis and Zachariasse (1988), Jaramillo and Oboh-Ikuenobe (1999); Pross and Brinkhuis (2005); Iakovleva (2015); Awad and Oboh-Ikuenobe (2016) Habibacysta Habibacysta tectata Cold water masses Head (1994; 1996); De Schepper et al. (2009)

Impagidinium Impagidinium spp. Outer neritic to oceanic, generally in Harland (1983); Wrenn and Kokinos (1986); warm climate, Oligotrophic Edwards and Andrle (1992); Brinkhuis et al. (1992); Brinkhuis and Biffi (1993); Zevenboom et al. (1994); Mudie and Harland (1996); Dale (1996); Powell et al. (1996); Jaramillo and Oboh-Ikuenobe (1999); Gedl (2005); Pross and Brinkhuis (2005); Iakovleva (2011; 2015) Nematosphaeropsis Mostly N. labyrinthus and N. Outer neritic-oceanic, dominate as Wall et al. (1977); Harland (1983); de Vernal lemniscata oceanic, temperate, cool-temperate and Mudie (1989); Brinkhuis et al. (1992); conditions in surface waters. Brinkhuis and Biffi (1993); Zevenboom et al. (1994); Dale (1996); Jaramillo and Oboh- Ikuenobe (1999); Pross and Brinkhuis (2005); Iakovleva (2015) Thalassiphora Thalassiphora spp. High productivity, cooling of surface Vonhof et al. (2000); Pross and Brinkhuis water (2005); Iakovleva (2011, 2015) Cerebrocysta Mostly C. namocensis Offshore Gedl (2005); Pross and Brinkhuis (2005); Iakovleva (2015) Hystrichokolpoma Mostly H. rigaudiae Offshore Brinkhuis et al. (2003a, 2003b); Pross and Brinkhuis (2005); Gedl and Peryt (2011); Iakovleva (2015) Lingulodinium Mainly L. machaerophorum Nearshore-offshore, L. Goodman (1979); Islam (1984); Brinkhuis et and L. pycnospinosum machaerophorum is more offshore al. (1992); Zevenboom et al. (1994); Dale and indicate warm water conditions; (1996); Jaramillo and Oboh-Ikuenobe (1999); euryhaline, can also be found in Sluijs et al. (2005); Crouch and Brinkhuis coastal/brackish marine settings, (2005); De Schepper et al. (2009); Iakovleva tolerant of salinity changes and (2015) indicative of high nutrient settings.

Cleistosphaeridium Mostly C. ancyreum and C. Shallow water, coastal settings Kӧthe (1990); Jaramillo and Oboh-Ikuenobe diversispinosum (1999); Pross and Brinkhuis (2005) Open-marine neritic-offshore Brinkhuis et al. (2003a, 2003b); Sluijs et al. (2005) Filisphaera Mainly F. filifera and Cold water masses, cool temperate to de Vernal and Mudie (1989); Head Bitectatodinium tepikiense subarctic conditions, open water shelf (1994;1996); De Schepper et al. (2009) environments. Heteraulacacysta H. campanula Warm water settings, restricted marine Pross and Brinkhuis (2005); Iakovleva (2011, with high salinity 2015) Impletosphaeridium Impletosphaeridium spp. open marine neritic water masses Brinkhuis (1994) Operculodinium Mostly O. centrocarpum Neritic-oceanic; cosmopolitan genus; Davey and Rogers (1975); Wall et al. (1977); mostly abundant offshore due to Harland (1983); Islam (1984); Wrenn and transportation; euryhaline; equatorial Kokinos (1986); Brinkhuis et al. (1992); to polar Edwards and Andrle (1992); Brinkhuis (1994); Dale (1996); Jaramillo and Oboh-Ikuenobe (1999); Iakovleva (2015) Spiniferites Including Spiniferites spp., Inner, middle to outer neritic; open Wall et al. (1977); Liengjarern et al. (1980); Achomosphaera spp., and marine, acme generally in upper shelf Islam (1984); Hultberg and Malmgren (1986); Hafniasphaera spp. due to transportation, broad thermal Brinkhuis and Zachariasse (1988); Brinkhuis et tolerance, tropical-subtropical. al. (1992); Edwards and Andrle (1992); Brinkhuis (1994); Jaramillo and Oboh- Ikuenobe (1999); Iakovleva (2011, 2015) Cribroperidinium Mostly C. giuseppei and C. Strong upwelling periods, deep and Kӧthe (1990); Jaramillo and Oboh-Ikuenobe tenuitabulatum cool water, coastal taxa (1999); Willumsen et al. (2014); Iakovleva (2015) Lejeunecysta Including Lejeunecysta spp. Shallow cold-water with high Brinkhuis et al. (1992); Sluijs et al. (2005); and Selenopemphix spp nutrients availability, nearshore, Gedl (2005); Guerstein et al. (2008); Iakovleva brackish eutrophic settings, abundant (2011; 2015) during high productivity periods, accompanied by ancient deltaic settings and facies that are organic rich. Polysphaeridium Including Eocladopyxis spp., Restricted marine-inner neritic, low- Kӧthe (1990); Brinkhuis (1994); Dale (1996); Polysphaeridium spp., and middle latitudes, lagoon and Jaramillo and Oboh-Ikuenobe (1999); Homotryblium spp. equatorial, low/high salinity, warm Iakovleva et al. (2001); Crouch and Brinkhuis water settings. (2005); Gedl (2005); Pross and Brinkhuis (2005); Iakovleva (2015)

202

Fig. 4. Relative abundances (in percent) of selected dinoflagellate cysts and terrestrial palynomorphs (pollen and spores) in the Late Eocene-Early Miocene interval. Note the absence of following samples due to the recovery of <100 specimens: S5, S10, S11, S13, S19, S25, S26.

203

The Polysphaeridium group (mainly Polysphaeridium zoharyi), which is an indicator of hypersaline environments (e.g., Iakovleva et al., 2001; Pross and Brinkhuis,

2005; Sluijs and Brinkhuis, 2009; Zonneveld et al., 2013), is present in this interval and its percentage ranges from 2 to 13.9%. We do not think that the presence of this species is an indication of any change from oceanic to restricted marine. However, we suspect that the presence of this group results from the transportation from nearshore settings. This conclusion is mainly based on its presence with other oceanic dinoflagellate cyst taxa and on the lithology and trace fossil evidences that support deeper conditions.

The dinoflagellate cyst assemblages in interval 2 are represented by both warm and cold-water species. Representatives of warm water species are Impagidinium spp.,

Lejeunecysta group, Lingulodinium machaerophorum and Polysphaeridium spp.

(Zevenboom et al., 1994; Zonneveld et al., 2013). On the other hand, the indicators of cold water masses are Cribroperidinium spp., Habibacysta tectata, Nematosphaeropsis spp., and Thalassiphora spp. (de Vernal and Mudie, 1989; Kӧthe, 1990; Zevenboom et al., 1994;

Matthiessen and Brenner, 1996; Jaramillo and Oboh-Ikuenobe, 1999; De Schepper et al.,

2009).

The particulate organic matter components (Fig. 5) in this interval are still dominated by AOM (66.8-85.6%) and followed by few to common occurrences of degraded phytoclasts (6.8-20%); an increase in the opaque particles is noted in the lower part of the interval. El Beialy et al. (2016) and Zobaa et al. (2011b) indicate that there are several processes responsible for the formation of opaque particles, such as the oxidation of the woody fragments due to long transportation period, post depositional alteration,

204 and/or natural wildfires. The superabundance of AOM integrated with the dinoflagellate cyst data, lithology and trace fossils information supports deeper environmental conditions.

4.3. INTERVAL 3 (LATE CHATTIAN-LATE AQUITANIAN, 317.94-262.69 MBSF)

Variable percentages ranging from rare to superabundant are recorded for the following taxa in this interval: Batiacasphaera spp. (1.2-36.9%), Lingulodinium spp.

(mainly L. machaerophorum; 0.3-20.7%), Polysphaeridium group (4-85%) and

Spiniferites group (4.3-34.7%) (Fig. 4). Moreover, several of the taxa recorded in interval

2 range through interval 3 as follows: Cerebrocysta spp. (0.3-4%), Cleistosphaeridium spp.

(0.4-1.7%), Filisphaera group (0.5%), Habibacysta tectata (0.3-0.85%), Impagidinium spp. (0.3%), Impletosphaeridium spp. (0.3-0.8%), Lejeunecysta group (0.5-2.8%),

Nematosphaeropsis spp. (0.3-3.4%), Thalassiphora spp. (0.3%). Heteraulacacysta campanula (0.5-11%) is recorded for the first time and mainly restricted to this interval.

The percentage of sporomorphs declines slightly in this interval vs interval 2 and ranges from 6-17 %. Three superabundance bioevents of the Polysphaeridium group are recorded throughout this interval: one is observed in sample S21 (317.94 mbsf; 75%), while the other two are noted in the middle part of interval 3, in in samples S18 (297.95 mbsf, 85%) and S17 (293.81 mbsf, 45.6%).

Oboh-Ikuenobe (2018) noted the concentration of several last occurrences of dinoflagellate cyst assemblages in the same interval and concluded that it was a hiatus event in this part of the interval. This conclusion is also supported by the presence of authigenic minerals such as pyrite and glauconite which reflect low sedimentation rate during the earliest Early Miocene (see Fig. 3 in Awad and Oboh-Ikuenobe, 2018).

205

Therefore, based on the superabundance of the Polysphaeridium group, last occurrences of several dinoflagellate cyst taxa, and the dominance of glauconite in this part of the interval

(Shipboard Scientific Party, 1996), we suggest a change in the environment from outer neritic-oceanic in interval 2 to restricted marine environment in the lower and middle parts of interval 3 (Fig. 4). However, we also suggest the possibility of “hyperstratification” conditions that were described by Reichart et al. (2004) in the Pleistocene open-oceanic sediments from the Arabian Sea. They described this phenomenon as a lack of winter mixing with continuous evaporation resulting in the development of very high sea surface salinity and a shallow and unusually strong pycnocline. The strong pycnocline provided a virtual seafloor, enabling P. zoharyi to complete its life cycle prior to sinking into deep waters .

In the upper part of interval 3 (samples S16-S12, 290.14-262.69 mbsf), the

Polysphaeridium group starts to decline in its relative abundance as the following species increase: Batiacasphaera spp. (22-37%), Hystrichokolpoma spp. (32%) and Lingulodinium spp. (20.7%). Pross and Brinkhuis (2005) noted that some species of Batiacasphaera are abundant in offshore settings; these species have also been recorded in sediments from other offshore sites, such as the Atlantic shelf (Stover, 1977), NW Tunisia (Brinkhuis and

Zachariasse, 1988), and ODP Hole 959D (Awad and Oboh-Ikuenobe, 2016).

Hystrichokolpoma rigaudiae is a cosmopolitan species that can be found in a wide range of environments (Brinkhuis, 1994); however, some studies indicate that its abundance is more common in offshore settings (Pross and Brinkhuis, 2005; Gedl and Peryt, 2011;

Iakovleva, 2015). Zonneveld et al. (2013) proposed that the high abundance of

Lingulodinium machaerophorum is noticed in sediments close to upwelling cells or below

206 river discharge plumes. This species has a broad salinity range (low and high salinity levels) and its abundance may be an indicator of high nutrient availability (Dale 1996;

Crouch and Brinkhuis, 2005; Zonneveld et al., 2013). The co-occurrence of the aforementioned species with other oceanic taxa (e.g., Impagidinium, Nematosphaeropsis,

Thalassiphora) in the upper part of interval 3 suggests deeper oceanic conditions than the lower and middle parts of the interval (Wall et al., 1977; Edwards and Andrle, 1992; Udeze and Oboh-Ikuenobe, 2005; Guerstein et al., 2008; Iakovleva, 2011, 2015). In addition, superabundances of Polysphaeridium group in several samples throughout this interval may support typical warm water temperatures in an equatorial region (Zonneveld et al.,

2013)

The percentage of degraded phytoclasts in interval 3 is higher than that in interval

2 (2.4-28.8%), but AOM is still dominant (58-92%) (Fig. 5). Shipboard Scientific Party

(1996) described the lithology of this interval as deep water facies (diatomite) with high abundance of plant debris. They indicated that the dominance of diatoms supports a general basinal setting for unit II with high nutrient availability; however, the source of this high nutrient supply is unknown. According to Shipboard Scientific Party (1996), the high contents of degraded phytoclasts in this interval and intervals 4 and 5 (see later discussion) suggests that the nutrients were transported offshore through fluvial outflow and/or strong, deep water upwelling episodes.

4.4. INTERVAL 4 (LATE AQUITANIAN- MIDDLE BURDIGALIAN, 244.61- 209.1 MBSF)

Sample S10 (244.61 mbsf) at the bottom of this interval records a remarkable drop in the relative abundance of dinoflagellate cysts to ⁓24% of the total palynomorph contents

207 and an increase in sporomorphs (76%). Apart from Batiacasphaera spp. (12%), other dinoflagellate cyst taxa (Cerebrocysta, Cleistosphaeridium, Cribroperidinium,

Habibacysta tectata, Hystrichokolpoma, Lingulodinium, Polysphaeridium, Spiniferites) are rare (<5%) (Fig. 4). We propose two possible reasons for the excellent preservation and sudden increase in pollen and spores and absence of oceanic dinoflagellate cyst taxa (e.g.,

Impagidinium, Nematosphaeropsis, Thalassiphora; Fig. 4). First, rapid transportation by turbidity currents resulted in the excellent preservation of enormous amounts of pollen and spores to the offshore site. Second, bioturbations/diagenesis possibly affected the preservation and recovery of dinoflagellate cysts. Shafik et al. (1998b) related the poor to moderate preservation of calcareous nannofossils and abundant unidentifiable nannofossil debris in this bottom part of interval 4 to possible dissolution.

Dinoflagellate cysts return to dominance upsection in the interval (samples S9-S3,

239.87-209.1 mbsf) (Fig. 4), while sporomorphs vary from common to abundant (11.8-

27.5%). A superabundance of the Spiniferites group (54%) is observed in sample S9

(239.87 mbsf). We also note the superabundance of Batiacasphaera spp. (47%) and abundance of Cerebrocysta spp. (30%) in sample S8 (235.24 mbsf), and superabundance of the Polysphaeridium group (44.8%) in sample S3 (209.1 mbsf). Other dinoflagellate cyst species and groups in samples S9-S3 include: Cleistosphaeridium spp. (0.3-3%),

Filisphaera group (0.5%), Hystrichokolpoma spp. (0.7-7%), Impagidinium spp. (0.7%),

Impletosphaeridium spp. (0.3-0.8%), Lejeunecysta group (0.3-0.5%), Lingulodinium spp.

(0.3-18.7%), Nematosphaeropsis spp. (0.8-4.8%), Operculodinium spp. (0.4-13.8%), and

Thalassiphora spp. (0.3%).

208

Fig 5. Relative abundances (in percent) of the particulate organic matter components in the studied section. A total of 500 particles were point counted for each sample.

209

The presence of outer neritic dinoflagellate cysts (Hystrichokolpoma;

Impletosphaeridium; Lingulodinium) alongside some oceanic taxa (Impagidinium,

Nematosphaeropsis, Thalassiphora) supports deeper conditions compared to sample S10

(Brinkhuis, 1994; Zevenboom, 1995; Brinkhuis et al., 2003a, 2003b; Pross and Brinkhuis,

2005). Brinkhuis et al. (2003a) noticed several intervals of abundant Cerebrocysta spp. in the Early Miocene of ODP Site 1168 in the western margin of Tasmania. This bioevent is also observed in the present study and its abundance is more common in hemipelagic deposits (Brinkhuis et al., 2003a, 2003b; Gedl, 2005; Pross and Brinkhuis, 2005). The superabundance of the Polysphaeridium group in sample S3 (209.1 mbsf), its co- occurrence with neritic-oceanic taxa, and low relative abundance of sporomorphs may be indicative of hyperstratification conditions (see section 4.3) rather than transportation by turbidity currents (Reichart et al., 2004; Oboh-Ikuenobe et al., 2017). Shipboard Scientific

Party (1996) noted that the high percentages of degraded phytoclasts in this interval (Figs.

5 and 8) are not necessarily indicative of a shallowing depositional environment.

4.5. INTERVAL 5 (BURDIGALIAN, 200.5-193.25 MBSF)

Sample S2 (200.5 mbsf) records a superabundance of Cribroperidinium spp.

(48.4%, mostly C. giuseppei and C. tenuitabulatum) and very high contents of sporomorphs (39.6%). The absence of the Polysphaeridium group is an interesting observation because it is superabundant upsection in sample S1 (56.7%, 193.25 mbsf) as well as other parts of the studied section. Rare to few occurrences of other dinoflagellate cysts through this interval include: Batiacasphaera spp. (2.5-3.5%), Hystrichokolpoma spp. (0.8-3.9%), Impagidinium spp. (0.3-1%), Lingulodinium spp. (0.3-1%),

210

Nematosphaeropsis spp. (0.3-7.4%), Operculodinium spp. (1.1-1.7%), and Spiniferites spp. (5-6%). Kӧthe (1990) noticed an abundance of Cribroperidinium in some boreholes in northwest Germany and interpreted this high percentage as an indicator of deep and cold-water conditions. In addition, other studies recorded a superabundance of this genus in Miocene sediments, such as those from the offshore Angolan Basin, West-central Africa

(Willumsen et al., 2014) and Venezuela (Demchuk et al., 2004). In the present study, we infer the superabundance of this genus in interval 5 as a very distinctive bioevent supporting a strong upwelling episode because deep water diatomite facies were dominant at this time. This interpretation is supported by the absence of the Polysphaeridium group in sample S2, which is generally indicative of warm conditions, high salinity and restricted marine or hyperstratified conditions (e.g., Stover, 1977; Kӧthe, 1990; Reichart et al., 2004;

Sluijs et al., 2005; Zonneveld et al., 2013). Moreover, the presence of other outer neritic- ocean dinoflagellate cyst taxa in the same sample (e.g., Impagidinium and

Nematosphaeropsis) emphasizes the suggested paleoenvironment and paleoclimatic assignment for this part of the interval (e.g., Zevenboom et al., 1994; Zevenboom, 1995;

Pross and Brinkhuis, 2005).

The superabundance of the Polysphaeridium group (mainly P. zoharyi) in sample

S1 (Fig. 4) may be indicative a slight change in the paleoenvironment and paleoclimate conditions. However, increasing percentages of Nematosphaeropsis spp. (mostly N. labyrinthus and N. lemniscata) from 0.3% in sample S2 to 7.3% in sample S1 still supports oceanic influence (Udeze and Oboh-Ikuenobe, 2005). Both N. labyrinthus and N. lemniscata may be synonymous (Rochon et al., 1999) and N. labyrinthus is a cosmopolitan extant species that tends to be found in both eutrophic and oligotrophic environments with

211 broad temperature tolerance (Zonneveld et al., 2013). This species has been noted to increase with water depth and used to indicate oceanic influence in several studies (e.g.,

Wall et al., 1977; Zevenboom et al., 1994; Dale, 1996; Head, 1998; Jaramillo and Oboh-

Ikuenobe, 1999; Pross and Brinkhuis, 2005; Iakovleva, 2015). Palynofacies analysis in interval 5 indicates a close relationship between AOM (40-57%) and degraded phytoclasts

(35-40%), while the number of fungal remains increases (7.4%) compared to the other intervals. The fungal spores were probably transported offshore.

212

Fig. 6. Photomicrographs no 1 of dinoflagellate cysts. A, B. Batiacasphaera spp. A. Uncertain view, high focus, S22, EF L33/2. B. Uncertain view, high focus, S14, EF K30. C. Bitectatodinium tepikiense. Left lateral view, high focus, S28, EF L20/4. D. Cerebrocysta? namocensis. Right lateral-dorsal view, high focus, S16, EF J28/2. E. Cleistosphaeridium sp. Uncertain view, mid focus, S14, EF K30. F. Cribroperidinium giuseppei. Ventral view, high focus, S2, EF M35/3. G. Cribroperidinium tenuitabulatum. Dorsal view, mid focus, S2, EF F43. H. Filisphaera filifera. Dorsal view, low focus, S28, EF O10. I. Habibacysta tectata. Ventral view, high focus, S10, EF T9/1. J. Heteraulacacysta campanula. Uncertain view, mid focus, S17, EF J31. K. Homotryblium plectilum. Uncertain view, mid focus, S28, EF F24. L. Homotryblium tenuispinosum. Apical view, low focus, S17, EF L31/3. M. Homotryblium vallum. Uncertain view, mid focus, S28, EF S23/1.

213

Fig. 7. Photomicrographs no 2 of dinoflagellate cysts. A. Hystrichokolpoma rigaudiae. Ventral view, high focus, S4, EF G38/4. B. Impagidinium sp. Uncertain view, high focus, S5, EF J29/4. C. Impletosphaeridium sp. Apical view, low focus, S25, EF F33/1. D. Lejeunecysta hyalina. Dorsal view, mid focus, S16, EF J32/2. E. Lingulodinium machaerophorum. Uncertain view, low focus, S26, EF J9/3. F. Nematosphaeropsis labyrinthus. Uncertain view, low focus, S22, EF Q28/2. G. Nematosphaeropsis lemniscata Dorsal view, high focus, S22, EF Q28/2. H. Operculodinium centrocarpum. Dorsal view, mid focus, S27, EF J36/1. I. Polysphaeridium zoharyi. Antapical view, high focus, S18, EF Q39. J. Selenopemphix nephroides. Apical view, high focus, S16, EF G38. K. Spiniferites pseudofurcatus. Dorsal view, mid focus, S27, EF V35/4. L. Thalassiphora sp. Uncertain view, mid focus, S22, EF U26/2.

214

Fig. 8. Photomicrographs no 3 of dinoflagellate cysts. A, B. Amorphous organic matter (AOM) particles. A. ODP Hole 959A, 311.20 mbsf, sample S20. B. ODP Hole 959A, 439.46 mbsf, sample S29. C, D. Degraded phytoclast particles. ODP Hole 959A, 411.77 mbsf, sample S26. E. Structured phytoclast particle. ODP Hole 959A, 411.77 mbsf, sample S26. F. Planispiral microforaminiferal inner test lining. ODP Hole 959A, 223.55 mbsf, sample S6. G. Opaque particle. ODP Hole 959A, 394.08 mbsf, sample S24. H. Fungal spore. ODP Hole 959A, 394.08 mbsf, sample S24. I. Acritarch sp. ODP Hole 959A, 297.95 mbsf, sample S18. J. Psilate trilete embryophyte spore (Deltoidospora). ODP Hole 959A, 274.23 mbsf, sample S14. K. Triporate pollen (Porocolpopollenites sp). ODP Hole 959A, 311.20 mbsf, sample S20.

215

5. CONCLUSIONS

(1) Five paleoenvironmental palynological intervals (interval 1-interval 5) are

described based on detailed dinoflagellate cyst and palynofacies analyses of ODP

Hole 959A.

(2) An arctic migration of the high latitude dinoflagellate cyst marker species

Bitectatodinium tepikiense and Filisphaera filifera is indicated by their abundance

in upper part of interval 1 during the Early Oligocene (early Rupelian). These

bioevents are indicators of prevailing cold-water masses during this interval.

(3) Integrating previously published lithological and microfossil data with important

dinoflagellate cyst bioevents in the present study reveals the presence of one hiatus

event in interval 3 during the Early Miocene (Aquitanian).

(4) The remarkable superabundances of the Polysphaeridium group (Homotryblium

spp. and Polysphaeridium spp.) in the deep basinal sediments throughout the

studied interval may be due to one of the following: transportation from an inner

neritic environment to the offshore site by strong turbidity currents, hiatus event or

hyperstratified conditions.

(5) High nutrient availability is indicated by the superabundance of Cribroperidinium

spp. in interval 5 at the top of the studied section during the latest Early Miocene

(Burdigalian). Representatives of this genus are common in cool and deep-water

environment characterized by strong upwelling conditions.

216

ACKNOWLEDGMENTS

We acknowledge the Department of Geosciences and Geological and Petroleum

Engineering, Missouri University of Science and Technology for funding this study and extend our appreciation to Dr. Mohamed Zobaa for the useful discussions.

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Walaa K. Awad, Francisca E. Oboh-Ikuenobe

Geology and Geophysics Program, Department of Geosciences and Geological and

Petroleum Engineering, Missouri University of Science and Technology, 129 McNutt

Hall, Rolla, MO 65409-0410, USA

ABSTRACT

Twenty-four samples covering a 85.35-meter interval representing the Late Eocene to Early Miocene in W-17001 in southeastern Florida are analyzed for a high-resolution palynological study. We use the presence of Priabonian marker dinoflagellate cyst taxa, such as Hemiplacophora semilunifera and Schematophora speciosa alongside Diphyes colligerum in one productive sample to propose a possible Late Eocene age for the lower part of the interval (Ocala Limestone). A hiatus event marked by the absence of diagnostic

Late Oligocene taxa is observed within the Arcadia Formation; Early Miocene marker taxa immediately succeed the Rupelian or early Chattian? species. Another hiatus event is noted in the Early Miocene based on several last occurrences of dinoflagellate cyst taxa.

Constrained cluster analysis of the relative abundances of seven groups of particulate organic matter components is used to establish three palynofacies intervals

(interval 1-interval 3) in the studied section. Amorphous organic matter and opaque phytoclasts are the predominant components and their abundances alternate in the section.

Marine palynomorphs (mainly dinoflagellate cysts) are productive in interval 2 and rare in

226 intervals 1 and 3; cluster analysis of dinoflagellate cysts yielded three intervals designated interval A to interval C, all within interval 2 except for the bottom sample in interval 1.

Terrestrial palynomorphs, degraded phytoclasts, structured phytoclasts, and fungal remains occur as minor components. By integrating lithologic characteristics, palynofacies analysis, and the superabundance of the Homotryblium group with common occurrence of

Glaphyrocysta spp., we infer an inner neritic environment for the productive intervals of the studied section.

Key words: Dinoflagellate cysts; palynofacies; Late Eocene-Early Miocene; biostratigraphy; paleoenvironment; Ocala Limestone; Suwannee Limestone; Arcadia

Formation; southeastern Florida.

1. INTRODUCTION

Several studies have focused on the Paleogene-early Neogene sediments in different parts of the world to better understand the transition from greenhouse to icehouse conditions (Wing and Greenwood, 1993; Sluijs et al., 2005; Pross and Brinkhuis, 2005;

Zachos et al., 2008). While it has been difficult to reconstruct a global biostratigraphic scheme for this time interval because of the dynamic climatic changes, dinoflagellate cysts have proved to be a very promising tool for reconstruction. Dinoflagellates are sensitive to changes in the climate, environmental conditions, salinity and sea surface temperature

(Sluijs et al., 2005), and are used for relative age dating and inferring paleoenvironment, paleoclimate, and paleoceanography (e.g., Pross et al., 2010; Soliman, 2012, Soliman et al., 2012; Bijl et al., 2018; Awad and Oboh-Ikuenobe, 2018).

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Published information on the Late Eocene-Early Miocene in the southeastern part of the Florida Peninsula is scarce (Brewster-Wingard et al., 1997). One of the main reasons for this dearth in data is the lack of good Oligocene outcrop exposures in the region; most

Oligocene sediments are found in the subsurface. Brewster-Wingard et al. (1997) integrated multiple proxies in several wells to reconstruct the biostratigraphy and paleoenvironment of this time interval. In the present study, we reexamine one of their wells (W-17001, Fig. 1) using high-resolution dinoflagellate cyst and palynofacies data to better understand the transition between the Eocene-Oligocene and Oligocene-Miocene boundaries. The major objective of the study is to establish a biostratigraphic scheme using dinoflagellate cyst data (Fig. 1). In addition, we reconstruct the paleoenvironment of the studied interval based on detailed dinoflagellate cyst and palynofacies data as well as lithologic characteristics.

Fig. 1. Map showing the location of W-17001 in the southeastern part of Florida, USA (modified from http://www.mappery.com/map-of/Gulf-of-Mexico-Map)

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2. GEOLOGIC SETTING

W-17001 (latitude 27°08´ 58̋ N and longitude 81° 21´ 15̋ W) was drilled in January

1992 and recovered a total of 389.8 meters (m) of sediment. It is located in Highlands

County in the southeastern part of the Florida Peninsula (Fig. 1). The Florida platform is located in the south-central part of the North American plate and separates the Gulf of

Mexico from the Atlantic Ocean. Its greatest width is about 565 kilometers and it extends southeast for more than 725 kilometers.

2.1. TECTONICS

When Pangea rifted apart during the Triassic, Florida’s igneous and sedimentary foundation separated from the African plate (Scott, 2001). Unlithified to well lithified middle Jurassic to Holocene sediments lie unconformably upon the eroded surface of the basement rocks. Carbonate sedimentation was dominant on most of the Florida platform from the middle Jurassic to the middle Oligocene. Due to the renewed uplift and erosion in the Appalachian highlands and sea level fluctuations, siliciclastic sediments predominated from the middle Oligocene to Holocene (Scott, 1988, 2001; Arthur et al.,

2008). The separation of Pangea in the Late Triassic, which started between northeast

Africa and North America and formed the Triassic-Jurassic rift basins (Manspeizer, 1994), also initiated the formation of the Straits of Florida. The rifting started during the Jurassic and spread out, forming the oceanic crust on the basin. Dramatic changes happened to this area within a very short time (5-10 million years) and the environment changed completely from terrestrial to marine.

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2.2. LITHOSTRATIGRAPHY

This interval consists mainly of three formations, the Late Eocene Ocala Limestone, the Early Oligocene Suwannee Limestone, and Early Oligocene-Middle Miocene Arcadia

Formation (Arthur et al., 2008; Fig. 2). The Ocala Limestone underlies the Suwannee

Formation, while two members of the Arcadia Formation, the Nocatee Member and Tampa

Member overlie the Suwannee Formation (Scott, 1988; Arthur et al., 2008). The lower part of the Ocala Limestone varies from white to light gray packstone to a grainstone with high dolomitization content, while the upper part has a chalky appearance with almost no dolomite. Brewster-Wingard et al. (1997) noted the difficulty in recognizing the boundary between the Ocala Formation and the overlying Suwannee Formation. However, the Ocala

Limestone is generally cleaner and has finer grains than the Suwannee Formation which has less non-calcitic material and is more skeletal (Arthur et al., 2008). The Paleontological studies for the Ocala Formation indicate a Late Eocene age (Arthur et al., 2008)

The Suwannee Limestone consists of microfossiliferous grainstone to wackestone with small amounts of sand and clay. Cross-bedding and bioturbation are the main sedimentary structures throughout the formation (Arthur et al., 2008). The formation was dated as Early Oligocene based on the fossiliferous contents of mollusks, gastropods, echinoids and dinoflagellate cysts (Brewster-Wingard et al., 1997; Arthur et al., 2008).

Dolomite is the abundant component of the overlying Arcadia Formation with sporadic chert and clay beds. It was a long-held belief that the Arcadia Formation was only Miocene in age (Puri and Vernon, 1964; Braunstein, 1988). However, a detailed study of the lithological and paleontological contents by Brewster-Wingard et al. (1997) suggested that the both Nocatee Member (Early-Late Oligocene) and Tampa Member (Late Oligocene-

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Middle Miocene age) are in the lower part of the formation. They studied 12 cores and subjected the selected samples to isotopic, paleontological and petrographic analyses. Their results suggest a nearly continuous interval for the Oligocene with limited durations of hiatus, in addition to giving a relative age for the interval. They also suggested that the change from carbonate sediments to siliciclastics at the contact between the Suwannee and

Arcadia formations was as a result of fluctuation in sea level and the paleo-Gulf Stream.

Fig. 2. The lithostratigraphy of W-17001and sample horizons in the studied interval (The lithologic contacts between the formations are described from Arthur et al., 2008).

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3. MATERIALS AND METHODS

Twenty-four samples (15 grams/sample) were processed from 133.8 to 219.15 meters in W-17001(Table 1); four samples from the Suwannee and Ocala Limestone and the other 20 samples from the Arcadia Formation (Fig. 2). We described the lithology of the selected samples in detail during a visit to the Florida Geological Survey Repository

(see Fig. 3 and Table 2). All the samples were examined in detail for their dinoflagellate cyst contents (Table 3) and particulate organic matter (Table 4). The organic fractions of the samples were extracted using standard laboratory techniques of digesting the sediments in hydrochloric and hydrofluoric acids (Traverse, 2007). Kerogen slides were mounted on glass slides after which the remaining organic residues were screened through 10 μm sieves and a second set of slides were mounted. A minimum of 200 dinoflagellate cysts was counted per sample, except for those samples with poor yields, in order to estimate the relative abundance of each taxon. The remaining palynological material in each slide was scanned for rare biostratigraphic marker taxa. Some of the studied samples are barren of dinoflagellate cysts (see Fig. 4), especially in the lower and upper parts of the studied interval, while the middle part is mostly productive.

Only samples with more than 100 dinoflagellate cyst specimens are used for quantitative analysis. The quantitative data were converted to percentages and discussed as follows: rare (<1-5%), few (6-10%), common (10-20%), abundant (20-40%) and superabundant (>40%). For identification and descriptions of the palynomorphs and particulate organic matter (POM), a Nikon transmitted light microscope with interference contrast was used. All the materials are housed in the palynological repository located in

232 the Paleontology Laboratory at Missouri University Science and Technology, USA. The plate captions contain details of the illustrated specimens, which include the sample number and England Finder (EF) reference. The systematic classification and nomenclature of dinoflagellate cysts follow Fensome et al. (2008) and Williams et al.

(2017), and descriptive terminology follows Evitt (1985) and Williams et al. (2000).

Additionally, palynofacies analysis involving point counts of 300 particles of POM per sample was undertaken in order to record variations in the proportions of terrestrial and marine organic components. The POM point count data as well dinoflagellate cyst counts in samples S8-S19 in the productive middle part and S24 at the bottom of the studied sequence were subjected to constrained cluster analysis CONISS using Tilia software

(Grimm, 2011). Cluster analysis classifies the data into groups and divides the section into intervals based on the similarities between them. With this large number of data set, this analysis gave a general overview about the distribution of the data and made it easier to interpret them. These results were integrated with lithologic characteristics to infer proximal-distal trends. The categories of POM identified are marine palynomorphs

(dinoflagellate cysts, foraminiferal linings, acritarchs), amorphous organic matter (AOM), terrestrial palynomorphs (pollen, spores, fungal remains), opaque phytoclasts, degraded phytoclasts, and structured phytoclasts.

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Table 1. List of samples and sample depths for Florida W-17001.

Samples Depth (m) S1 133.80

S2 136.55 S3 139.60 S4 143.26 S5 147.50 S6 150.88 S7 155.14 S8 160.00 S9 160.33 S10 163.07 S11 166.73 S12 172.82 S13 174.04 S14 178.00 S15 180.44 S16 182.58 S17 183.5 S18 185.32 S19 188.06 S20 191.11 S21 196.60 S22 206.96 S23 215.19 S24 219.15

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Table 2. Detailed lithologic description of the processed samples.

Samples Detailed lithologic description S1 Carbonate mud, chalky, light olive gray to light gray in color, mollusk fossil fragments, dark gravel size particles (⁓10%, possible phosphate), strong reaction with HCl. S2 Fossiliferous limestone, yellowish gray color, fossil fragments (gastropods and pelecypods), external and internal molds, clay grain size matrix, microcrystalline, phosphate mineral present, very strong reaction with HCl. S3 Calcilulite (limestone that has clay and silt grain size), olive gray to light gray in color, fossil fragments, very few phosphate minerals (~2%), very strong reaction with HCl. S4 Fossiliferous limestone, varies in color from white to yellowish gray, internal and external molds of mollusks (gastropods and pelecypods), spar calcite cement noted, microcrystalline, dolomite cement, very strong reaction with HCl. S5 Dolostone, white to grayish brown, dolomitized, speckled (dotted appearance), fossil fragments (gastropods and pelecypods), external and internal molds are common, medium reaction with HCl. S6 Fossiliferous limestone, white to yellowish gray, chalky, clay to silt clay size carbonate matrix, also microcrystalline in some parts, fossil fragments (bryozoans), phosphate mineral (<10%), dolomite cement, very strong reaction with HCl. S7 Dolostone, light olive gray to very light gray, mostly cryptocrystalline in some parts to fine grains in other parts, also sand size lithic fragments and quartz grains with dolomite cement observed, fossil fragments (gastropods and pelecypods), medium reaction with HCl. S8 Very fine-grained sandstone to siltstone, dark greenish gray, clay matrix with carbonate cement, little fossil fragments, phosphate mineral (⁓10%) and quartz sand grains (⁓40%), very weak reaction with HCl. S9 Very fine-grained sandstone to siltstone with clay matrix, grayish olive to dark greenish olive, carbonate cement, laminated, fossil fragments, phosphate minerals (⁓15%) and quartz sand size (⁓40%), strong reaction with HCl due to the presence of fossil particles and carbonate cement. S10 Silty clay, dark greenish gray to dark gray, fissile and laminated, fossil fragments not observed, dolomite cement, weak reaction with HCl due to dolomitization in some parts, lamination is not as distinct as shale. S11 Silty clay, moderate light gray to greenish black, bedded in some parts, dolomite cement, fossil fragments not observed, weak reaction with HCl. S12 Silty clay, greenish color to dark greenish gray, fissile, carbonate matrix, the clay percentage is not much in this sample compared to underlying samples, fossil fragments not observed, very weak reaction with HCl

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Table 2. Detailed lithologic description of the processed samples (Cont.)

Samples Detailed lithologic description S13 Silty clay, dark greenish gray, high percentages of clay matrix compared to previous samples, carbonate cement, fissile, fossil fragments not observed, very weak reaction with HCl. S14 Silty clay, dark greenish gray to bluish gray, quartz sand grains (⁓25%), clay matrix, phosphate minerals (<5%), very weak reaction with HCl due to dolomite cement and few fossil fragments. S15 Silty clay, dark greenish gray color, very high percentage of clay matrix resulting in very dark color compared to previous samples, fissile, quartz sand grains (~25%), fossil fragments not observed, very weak reaction with HCl. S16 Silty clay, dark greenish gray, fissile, quartz sand grains (<15%), carbonate cement, fossil fragments (pelecypods), moderate reaction with HCl. S17 Silty clay, dark greenish gray, clay matrix, fossil fragments (pelecypods, gastropods and ostracods), moderate reaction with HCl. S18 Silty clay, greenish gray to light gray, clay matrix, dolomite and quartz cements make this sample harder than previous sample, quartz sand grains (~20%), fossil fragments (pelecypods), medium reaction with HCl. S19 Silty clay, dark greenish gray, clay matrix with both dolomite and quartz cements, fossil fragments (pelecypods and gastropods), bioturbated, medium reaction with HCl. S20 Silty clay, brownish gray, fossil fragments, carbonate cements, this sample is not as hard as others that have both dolomite and quartz cement, weak reaction with HCl. S21 Fine sandstone, dark greenish gray to light gray, clay matrix, fossil fragments observed, very weak reaction with HCl. S22 Fossiliferous limestone, chalky and granular, fossil fragments observed, very strong reaction with HCl. S23 Coquina, white to very light orange, very granular and loose, fine to coarse grain size of pelecypods and gastropods particles, very strong reaction with HCl. S24 Fossiliferous limestone, yellowish gray, microcrystalline, fossil fragments (pelecypods), external and internal molds are common, strong reaction with HCl.

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Fig. 3. Pictures of some samples of the studied interval. A-F. Fossiliferous limestone from the Arcadia Formation. A, Note the external and internal molds of pelecypods, S2, 136.55 m. B, External mold with spar calcite cement, S4, 143.26 m. C, External mold of gastropods, S5, 147.5 m. D, Dolomitized sample, S7, 155.14 m. E. Bryozoans, S6, 150.88 m. F. Phosphate minerals, S1, 133.8 m. G-I. Silty clay from the Arcadia Formation. G. Rich with clay matrix, fissile in some parts and massive in other parts, S10, 163.07 m. H. Dolomite and quartz cements noticed in this sample, S20, 191.11 m. I. Note the fissile layers and very high clay percentage, S15, 180.44 m. J-L. Fossiliferous Ocala Limestone and Suwannee Limestone. J. Very fine grain size fossils, S22, 206.96 m. K. Fine to coarse grain size fossils, very loose and chalky, S23, 215.19 m. L. Gastropod external mold, S24, 219.15 m. The pen width used in some of these photographs is 1 mm.

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Table 3. Raw count data for dinoflagellate cyst species.

Depth (m) 150.88 160.00 163.07 166.73 172.82 174.04 178.00 180.44 182.58 183.50 185.32 188.06 191.11 219.15

Samples S6 S8 S10 S11 S12 S13 S14 S15 S16 S17 S18 S19 S20 S24

Achomosphaera grallaeformis 0 0 0 0 0 0 0 1 0 0 1 0 0 0

Areoligera spp. 1 0 0 0 0 0 1 0 0 0 0 0 0 0

Batiacasphaera spp. 4 0 2 3 2 0 1 3 7 0 1 2 0 0

Brigantedinium? spp. 0 0 2 0 0 0 0 0 0 0 0 0 0 0

Caligodinium pychnum 0 0 0 2 0 0 0 0 0 0 0 0 0 0

Chiropteridium spp. 7 0 0 0 4 2 2 0 0 0 3 0 0 0

Chiropteridium galea 0 0 0 0 2 0 0 3 0 0 1 1 0 0

Cleistosphaeridium spp. 1 0 0 0 0 0 0 1 1 0 0 3 1 1

Cleistosphaeridium ancyreum 0 0 0 0 0 0 0 0 0 0 0 1 0 0

Cordosphaeridium cantharellus 0 0 5 3 0 2 0 13 0 0 0 1 0 0

Cordosphaeridium fibrospinosum 0 0 0 0 0 0 0 0 0 0 0 1 0 0

Cribroperidinium spp. 1 0 4 1 0 2 79 42 0 36 32 1 5 0

Dapsilidinium pseudocolligerum 0 0 0 0 0 0 0 0 0 0 1 4 0 0

Deflandrea phosphoritica 0 0 0 0 0 0 0 0 0 0 0 1 0 1

Diphyes colligerum 0 0 0 0 0 0 0 0 0 0 0 0 2 1

Distatodinium spp. 0 0 0 0 0 0 0 0 0 0 0 0 0 1

Eocladopyxis peniculata 0 0 1 0 0 0 0 1 0 0 0 0 0 1

Glaphyrocysta spp. 0 0 39 0 31 15 10 3 0 0 1 0 0 0

Habibacysta tectata 0 0 1 0 0 0 0 0 0 0 0 0 0 0

Hemiplacophora semilunifera 0 0 0 0 0 0 0 0 0 0 0 0 0 2

Heteraulacacysta campanula 0 0 3 8 0 0 2 3 1 0 2 0 0 0

Homotryblium spp. 2 10 92 8 36 75 0 1 181 98 98 61 0 2

Homotryblium floripes 0 0 0 0 1 0 0 0 0 0 0 0 0 0

Homotryblium plectilum 0 0 9 5 32 57 0 0 0 40 37 41 0 0

Homotryblium tenuispinosum 0 0 0 0 0 0 0 0 0 0 0 1 0 0

Homotryblium vallum 0 1 1 0 1 0 0 0 0 0 0 1 0 0

Hystrichokolpoma spp. 1 0 7 27 1 9 1 16 0 1 1 7 1 2

Impletosphaeridium spp. 0 1 3 0 0 0 0 0 0 0 0 0 0 0

Kallosphaeridium biornatum 0 0 0 0 0 0 1 0 0 0 0 0 0 0

Lejeunecysta spp. 0 1 0 1 0 1 3 3 1 0 4 1 0 0

Lingulodinium spp. 0 0 0 0 0 0 1 0 0 0 0 0 0 0

Lingulodinium machaerophorum 0 0 0 2 0 0 0 0 0 0 1 0 3 0

Lingulodinium multivirgatum 0 0 0 3 2 3 0 0 0 0 0 0 0 0

Membranilarnacia? picena 0 0 1 0 1 1 0 0 0 0 0 0 0 0

Pentadinium spp. 0 0 0 1 0 0 1 0 0 0 0 0 0 2

Pentadinium granulatum 0 0 1 0 30 4 2 7 0 1 1 2 0 0

Operculodinium spp. 0 54 3 11 7 0 0 6 3 5 1 3 0 84

Operculodinium piaseckii 0 0 0 0 0 1 0 0 0 0 0 0 0 0

Polysphaeridium spp. 0 10 3 4 2 0 0 1 0 0 1 2 0 0

Polysphaeridium zoharyi 2 0 0 0 0 0 0 0 0 0 0 0 0 0

Schematophora speciosa 0 0 0 0 0 0 0 0 0 0 0 0 0 1

Selenopemphix nephroides 1 0 2 10 2 1 7 2 0 1 1 0 0 1

Spiniferites spp. 4 63 34 44 37 16 37 42 14 14 15 18 1 14

Spiniferites pseudofurcatus 0 0 2 4 16 10 2 3 0 3 4 0 1 2

Spiniferites mirabilis 0 0 0 0 0 0 0 1 0 0 0 0 0 0

Tuberculodinium vancampoae 0 0 0 0 0 1 0 0 0 0 0 0 0 0

Wetzeliella gochtii 0 0 0 0 0 0 7 50 0 0 0 1 0 0

Unidentified cysts 4 0 1 3 6 1 1 1 2 2 4 3 1 2

Total Counted 28 140 216 140 213 201 158 203 210 201 210 156 15 117

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Table 4. Point count data for particulate organic matter components.

Samples numbers Marine Terrestrial Amorphous Opaque Degraded Structured Fungal and palynomorphs palynomorphs organic matter phytoclasts phytoclasts phytoclasts remains Depth Total (m)

S1 10 0 191 93 12 2 0 308 (133.80) S2 16 4 230 53 5 0 0 308 (136.55) S3 5 11 99 206 0 1 0 322 (139.6) S4 0 0 90 215 1 0 2 308 (143.26) S5 33 2 31 235 3 0 0 304 (147.50) S6 10 4 117 186 3 0 0 320 (150.88) S7 7 1 210 81 4 0 0 303 (155.14) S8 91 7 119 82 6 2 0 307 (160.00) S9 12 0 157 79 4 0 58 310 (160.33) S10 95 0 73 130 4 0 0 302 (163.07) S11 54 1 230 23 3 0 0 311 (166.73) S12 87 1 155 44 14 1 0 302 (172.82) S13 45 1 13 246 2 0 0 307 (174.04) S14 25 1 135 141 1 0 0 303 (178.00) S15 85 3 194 15 5 0 0 302 (180.44) S16 16 3 128 160 0 0 0 307 (182.58) S17 21 2 137 140 5 0 0 305 (183.50) S18 39 0 155 94 15 0 0 303 (185.32) S19 21 3 260 14 4 0 0 302 (188.06) S20 21 0 210 73 4 0 1 309 (191.11) S21 9 0 51 238 10 0 0 308 (196.60) S22 5 0 143 157 0 0 0 305 (206.96) S23 41 4 64 143 45 0 3 300 (215.19) S24 19 1 199 80 24 1 3 327 (219.15)

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4. RESULTS AND DISCUSSION

4.1. DINOFLAGELLATE CYSTS BIOSTRATIGRAPHY

Forty-eight dinoflagellate cyst taxa are identified in the studied interval from W-

17001 (Table 3). The productive samples mostly yielded abundant and well-preserved dinoflagellate cysts. The stratigraphic ranges of the selected dinoflagellate cysts are shown in Figure 4.

Fig. 4. Range chart of the selected dinoflagellate cysts in the Late Eocene-Early Miocene interval of W-17001 (The Eocene-Oligocene boundary based on previous data from Brewster-Wingard et al., 1997 and Arthur et al., 2008).

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4.1.1. Samples S24-S20 (Priabonian-earliest Early Rupelian, 219.15-191.11 m).

Sample S24 has poor recovery; Diphyes colligerum, Deflandrea phosphoritica and

Selenopemphix nephroides are present, as are spot occurrences (SOs) of Hemiplacophora semilunifera and Schematophora speciosa. The overlying samples S23, S22 and S21 are barren of dinoflagellate cysts and other palynomorphs. Upsection, sample S20 records the last occurrence (LO) of D. colligerum and the first occurrence (FO) of Lingulodinium machaerophorum (Fig. 4).

The recovered dinoflagellate cysts in the basal sample of the studied section

(sample S24) suggest a Late Eocene (Priabonian) age (Bujak et al., 1980; Brinkhuis, 1994;

Sluijs et al., 2003; Williams et al., 2004; Kӧthe and Piesker, 2007; Awad and Oboh-

Ikuenobe, 2018). Age assignment for samples S23-S21 is uncertain since they are barren.

Sample S20 has very low recovery of dinoflagellate cysts with only 15 specimens. The LO of D. colligerum, which has inconsistent LO in different latitudinal regions, is recorded in this sample. Williams et al. (2004) assigned a Priabonian age (37 Ma) to the LO of D. colligerum in the mid-latitudes of the Northern Hemisphere and Early Oligocene (Rupelian,

33.27 Ma) in equatorial regions. Some studies have recorded this species in the Late

Eocene in the middle and high latitudes (e.g., Fensome et al., 2009; Fensome et al., 2016), while others have extended its age range to the Early Rupelian (e.g., Brinkhuis and Biffi,

1993; Soliman, 2012). Brewster-Wingard et al. (1997) observed that D. colligerum overlapped with Chiropteridium sp. at 199 m depth in W-17001 (a nearby sample S21 in the present study is barren). The FO of Chiropteridium sp. has been observed in the Early

Rupelian in several studies (Pross et al., 2010; Soliman, 2012) and its occurrence with D. colligerum supports a possible Early Oligocene age in this part of the interval.

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4.1.2. Samples S19-S14 (Rupelian-early Chattian?, 188.06-178.00 m). The LO of Deflandrea phosphoritica coincides with several FOs in sample S19, and these species

include Chiropteridium galea, Cordosphaeridium cantharellus, Dapsilidinium

pseudocolligerum, Homotryblium plectilum, Homotryblium vallum, Lejeunecysta spp.,

Pentadinium granulatum and Wetzeliella gochtii (Fig. 4). An abundance of H. plectilum is also observed in sample S19, followed by common occurrences in samples S18 and S17.

The LO of D. pseudocolligerum and the FO of Heteraulacacysta campanula occur in sample S18, The LO of W. gochtii and SO of Kallosphaeridium biornatum are recorded in sample S14.

Wetzeliella gochtii is considered a marker species for the Oligocene and its FO generally indicates an Early Oligocene (Rupelian) age. Brinkhuis (1992) observed the FO of this species within the Reticulatosphaera actinocoronata interval zone in the Early

Oligocene in northern Italy. Studies in other localities that recorded the Rupelian FO of this marker species include those in Tunisia (Torricelli and Biffi, 2001), southern North

Sea Basin (Van Simaeys et al., 2005), Italy (Pross et al., 2010), Austria (Soliman, 2012),

South Caspian Basin (Bati, 2015), and various localities (Brinkhuis and Biffi,1993, Sancay,

2005; Sancay et al., 2006; Köthe and Piesker, 2007; Bati and Sancay, 2007). Williams et al. (2004) also reported Rupelian FOs of C. galea and W. gochtii at 33.5 Ma and 32.8 Ma, respectively in several locations in the Northern Hemisphere mid-latitudes. The FO of

Chiropteridium spp. is generally recorded in the Rupelian (e.g., Wilpshaar et al., 1996;

Kӧthe and Piesker, 2007; Pross et al., 2010).

242

Fig. 5. Relative abundances (in percent) of selected dinoflagellate cysts in the Late Eocene- Early Miocene interval. Note the absence of following samples due to the recovery of <100 specimens: samples S7-S1 and samples S23-S20.

243

Fig. 6. Relative abundances (in percent) of the particulate organic matter components in the studied section. A total of 300 particles were point counted for each sample.

244

The FO of H. vallum in sample S19 is also considered Rupelian; this species was originally recorded in the Rupelian in the Blake Plateau (Stover, 1977). Kӧthe and Piesker

(2007) observed this species within dinoflagellate cyst subzone D12nc in the Rupelian of a borehole in Germany. Other studies also noted the FO of H. vallum in the Rupelian and considered it an important stratigraphic bioevent (e.g., Brinkhuis, 1994; Helenes and

Cabrera, 2003; Awad and Oboh-Ikuenobe, 2018). The presence of other species whose age ranges include the Rupelian further supports the proposed age assignment. In addition, K. biornatum and D. pseudocolligerum have been recorded in several Oligocene sections (e.g.,

Stover, 1977; Kӧthe and Piesker, 2007; Awad and Oboh-Ikuenobe, 2018).

The LO of W. gochtii has been recorded in the middle Chattian (Pross et al., 2010;

Soliman, 2012). Also, Williams et al. (2004) reported the LO of this species at 28.15 Ma

(Early Chattian) in equatorial regions and the Southern Hemisphere mid-latitudes and 26.6

Ma (middle Chattian) in the Northern Hemisphere mid-latitudes. We note here that Turkish studies have recorded the total range of W. gochtii in the Rupelian (Ediger, 1981; Sancay,

2005; Sancay et al., 2006; Bati and Sancay, 2007; Bati, 2015). Based on the inconsistent

LO of this species in different latitudinal regions, we consider its LO in sample S14 may indicate either Rupelian or early Chattian? age. In the present study, the LO of this species in sample S14, followed directly by Early Miocene marker species in sample S13 may suggest the absence of part of the Late Oligocene sediments, which indicates a hiatus event between these two samples. Although we give the possibility for different age assignment for this part of the interval, we suggest that the Chattian is not very well defined in the present study, due to the absence of diagnostic Chattian marker species.

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4.1.3. Samples S13-S6 (Aquitanian, 174.04-150.88 m). The FOs of

Lingulodinium multivirgatum and Membranilarnacia? picena, SOs of Operculodinium piaseckii and Tuberculodinium vancampoae and an abundance of H. plectilum are recorded in sample S13. The LO of C. galea coincides with common occurrences of H. plectilum

and P. granulatum in sample S12. This is followed by the LOs of L. machaerophorum and

L. multivirgatum, and the SO of Caligodinium pychnum in sample S11. The LOs of several species are observed in sample S10 which may indicate a third hiatus event in the studied

section of W-17001, and these species are C. cantharellus, H. campanula, H. plectilum, P. granulatum, and M. picena. The SO of Brigantedinium? spp. is also observed. Sample S8 records the LOs of H. vallum and Lejeunecysta spp. Samples S7-S1 (except Sample S6) are barren of dinoflagellate cysts and other palynomorphs (Fig. 4).

The FO of M. picena in sample S13 suggests an earliest Early Miocene

(Aquitanian) age for this part of the interval (Fig. 4). This species has been recorded in the early Aquitanian in several studies (Biffi and Manum, 1988; Brinkhuis et al., 1992;

Zevenboom et al., 1994; Zevenboom, 1995, Wilpshaar et al., 1996; Munsterman and

Brinkhuis, 2004, Awad and Oboh-Ikuenobe, 2018). M. picena is considered one of the closest bioevents to the Oligocene-Miocene boundary (Munsterman and Brinkhuis, 2004;

Williams et al., 2004; Awad and Oboh-Ikuenobe, 2018). However, Van Simaeys et al.

(2004, 2005) recorded this species in the Late Chattian based on its occurrence with other

Late Oligocene marker taxa. In the present study, the FO of this species with other bioevents that are commonly observed in the Early Miocene supports the proposed age for this part in W-17001. L. multivirgatum was originally described and recorded in the

Aquitanian of eastern USA (de Verteuil and Norris, 1996). Unlike other species of the

246 genus, this species has a very short stratigraphic range in the Aquitanian. The FO of O. piaseckii is also Early Miocene (e.g., de Verteuil and Norris, 1996; Brinkhuis et al., 2003;

Mao et al., 2004; Kӧthe and Piesker, 2007; Soliman et al., 2012; Awad and Oboh-Ikuenobe,

2018). The LO of C. galea has been recorded in the earliest Early Miocene (early

Aquitanian) or older sediments (Chattian age) (de Verteuil and Norris, 1996; Williams et al., 2004; Kӧthe and Piesker, 2007; Dybkjær and Piasecki, 2008, 2010), although recent a study by Awad and Oboh-Ikuenobe (2018) extends the range of this species to the latest

Early Miocene (Burdigalian). We suspect that latitudinal locations and differences in paleoenvironmental conditions (preservation conditions) may play a significant role for these disparities. Tuberculodinium vancampoae was previously considered mainly restricted to the Miocene with an Early Miocene FO (Stover, 1977; Williams and Bujak,

1977; Williams et al., 1993). However, more recent studies have noted the occurrence of this species in older sediments, extending down to the Chattian and Rupelian (Brinkhuis and Biffi, 1993; de Verteuil and Norris,1996; Torricelli and Biffi, 2001; Helenes and

Cabrera, 2003; Van Simaeys et al., 2005; Pross et al., 2010). Its presence with the

Aquitanian taxa supports the age assignment for this part of the studied interval.

4.2. PALEOENVIRONMENTAL RECONSTRUCTION

Palynomorph preservation in samples S19-S8 in the middle part of W-17001 is generally fair, and recovery varies from good to excellent. Sample near the bottom

(samples S23-S21) and top (samples S7-S1) parts of the section are barren of dinoflagellate cysts and other palynomorphs except foraminiferal test linings in the unoxidized (kerogen) fractions; only sample S24 is productive in bottom part of the sequence (Fig. 5). The

247 abundance of terrestrial palynomorphs (mostly pollen and spores) is generally less than dinoflagellate cysts in the middle part of the sequence. Selected dinoflagellate cyst group/species are represented in Figure 5 as follow: Batiacasphaera spp., Chiropteridium spp., Cordosphaeridium spp. (mainly C. cantharellus and C. fibrospinosum),

Cribroperidinium spp., Glaphyrocysta group (Areoligera spp. and Glaphyrocysta spp.),

Homotryblium group (Eocladopyxis spp., Heteraulacacysta spp., Homotryblium spp.,

Lingulodinium spp., and Polysphaeridium spp.), Hystrichokolpoma spp., Lejeunecysta group (Deflandrea spp., Lejeunecysta spp., Selenopemphix spp.) Pentadinium spp. (P. granulatum), Operculodinium spp., Spiniferites group (Achomosphaera spp. and

Spiniferites spp.), and Wetzeliella gochtii. The quantitative data represented in Figure 5 are only for samples with >100 dinoflagellate cyst specimens. The Homotryblium group dominates the dinoflagellate cyst assemblages, reaching up to 86.6% of the assemblage in sample S16 (182.58 m). Other groups/species that are generally present in every sample include: Chiropteridium spp., Glaphyrocysta group, Operculodinium spp., and Spiniferites group (Fig. 5).

POM analysis (palynofacies, Fig. 6) indicates an alternation between the two predominant components – AOM and opaque phytoclasts – throughout the studied interval.

Marine palynomorphs are dominant especially in the middle parts, while terrestrial palynomorphs, fungal remains, degraded phytoclasts and structured phytoclasts occur in low percentages. We have integrated results of the constrained cluster analysis of the POM in all 24 samples and dinoflagellate cyst data from the productive middle samples S8-S19 and sample S24 at the bottom with lithologic characteristics to better understand the changes in paleoenvironment in W-17001 (Figs. 5 and 6). Three palynofacies intervals

248 from the bottom to the top of the studied sequence (interval 1-interval 3) and three dinoflagellate cyst intervals (interval A-interval C) were identified (Fig. 5).

4.2.1. Palynofacies Interval 1, S24-S21 (Lower Part of Dinoflagellate Cyst

Interval A). There is a superabundance of opaque phytoclasts (47.6-77.3%) in all the samples except sample S24 which has a superabundance of AOM (60.6%). Sample S24 is also the only sample that is productive in dinoflagellate cysts in interval 1 and clusters with dinoflagellate cyst interval A (see section 4.2.2.1 for a discussion of the upper part of the interval). This sample records a high percentage of Operculodinium spp. (71.8%), common occurrences of Spiniferites group (13.7%), and rare occurrences of the Homotryblium group (2.5%), Hystrichokolpoma spp. (1.7%), Lejeunecysta group (1.7%), and

Pentadinium spp. (1.7%). Both Operculodinium spp. and the Spiniferites group are cosmopolitan and have been recorded in several settings ranging from inner neritic to oceanic environments (Wall et al., 1977; Iakovleva, 2011, 2015; Awad and Oboh-Ikuenobe,

2016).

The marine palynomorphs in kerogen samples S23-S21 are foraminiferal test linings, and other palynomorphs (pollen, spores and dinoflagellate cysts) are absent.

Processes that have been proposed as being responsible for the abundance of opaque phytoclasts in sediments are: (1) oxidation of woody fragments; (2) long period of transportation; (3) post depositional alteration, and/or (4) natural wildfires (El Beialy et al.,

2016; Zobaa et al., 2011b). The lithology of W-17001 in this part of the section is mainly fossiliferous limestone, indicating nearshore deposition without much indication of diagenetic processes (see lithologic description in Table 2). Therefore, we suspect that oxidation of woody fragments most likely resulted in the abundance of opaque phytoclasts.

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Pross and Brinkhuis (2005) noted that oxidation is the ultimate enemy of organic materials, including dinoflagellate cysts. This process probably contributed to the absence of dinoflagellate cysts and the low percentages of mostly degraded foraminiferal test linings

(1.6-13%) in samples S23-S21. While the low percentages of dinoflagellate cysts other than Operculodinium spp. and the Spiniferites group in only one sample provide little information for clear interpretations, their integration with lithologic and palynofacies data supports an inner neritic depositional environment for interval 1.

4.2.2. Palynofacies Interval 2, S20-S6 (Upper Part of Dinoflagellate Cyst

Interval A, Interval B and Interval C). Palynofacies interval 2 (samples S20-S6, 191.11-

150.88 m) is characterized by alternations of AOM (4.2-86%) and opaque phytoclasts (4.6-

80%) (Fig. 6). Marine palynomorphs (2.3-28%) are mainly represented by dinoflagellate cysts rather than foraminiferal lining tests. This interval includes the most productive samples of dinoflagellate cysts from the whole section and has three dinoflagellate cyst intervals (interval A-interval C). In order to better understand this palynofacies interval, a discussion about the POM will be included in the sections on the dinoflagellate cyst intervals below (Figs. 5 and 6).

4.2.2.1. Dinoflagellate cyst interval A (S19-S16). The Homotryblium group (66.5-

86.6%) dominates the samples in this upper part of interval A (Fig. 5). Rare to common occurrences are recorded for the following dinoflagellate cyst taxa: Batiacasphaera spp.

(0.5-3.3%), Chiropteridium spp. (0.6-1.9%), Cordosphaeridium spp. (1.3%),

Cribroperidinium spp. (0.6-18%), Glaphyrocysta (0.5%), Hystrichokolpoma spp. (0.5-

4.5%), Lejeunecysta group (0.5-2.4%), Pentadinium spp. (0.5-1.3%), Operculodinium spp.

(0.5-2.5%), Spiniferites group (6.7-11.5%), and Wetzeliella spp. (0.6%). The extinct genus

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Homotryblium has been interpreted as a restricted marine indicator (e.g., Brinkhuis, 1994) based on its similarity to the extant genus Polysphaeridium. The latter is more common in coastal, tropical-subtropical regions characterized by warm water and high salinity

(Zonneveld et al., 2013). However, the co-occurrence of Homotryblium spp. with an acme of the brackish water algae Pediastrum indicates their wide range of salinity tolerance

(Crouch and Brinkhuis, 2005; Sluijs et al., 2005; Soliman, 2012; Willumsen et al., 2014).

While it is difficult to suggest high salinity conditions based on Homotryblium, its superabundances indicate a shallow marine environment. There is also the possibility for this genus to be reworked into offshore sediments; they can be transported or occur in hyperstratified conditions (Stover, 1977; Gedl, 2004; Reichart et al., 2004). Glaphyrocysta spp. and Cordosphaeridium spp. are generally common in warm, inner neritic environment

(Brinkhuis, 1994; Slimani et al., 2010; Soliman, 2012). Pross et al. (2010) indicated that

Chiropteridium spp. is typically common in inner neritic environment. In addition, this genus has been related to high productivity periods and low salinity in coastal and neritic environments (Köthe, 1990; Brinkhuis 1994; Pross and Schmiedl, 2002). Cribroperidinium spp. and the Lejeunecysta group have been recorded from coastal and nearshore environments, tropical-subtropical conditions and high productivity periods (Brinkhuis et al., 1992; Sluijs et al., 2005; Gedl, 2005; Iakovleva, 2011, 2015). The silty clay sediments, macrofossil contents and dinoflagellate cyst data indicate shallowing conditions for this part of interval A.

The percentage of AOM in the lower part of palynofacies interval 2 is higher than that in interval 1 (41.7-86% vs. 16.5-60.8%), but opaque phytoclasts are still dominant in some samples (4-52%) (Fig. 6). Powell et al. (1992) linked the superabundance of AOM

251 to high productivity level, although they can result from the degradation of algal matter in reducing, low energy environments with high preservation potential (Oboh-Ikuenobe et al.,

2005; Zobaa et al., 2011a, 2013; El Beialy et al., 2016; Barron et al., 2017). We noticed that the increase in opaque phytoclasts correlates with low preservation potential of dinoflagellate cysts. For example, sample S19 has a very low percentage of opaque phytoclasts but excellent preservation of dinoflagellate cysts, while preservation ranges from poor to good in samples S20, S18, S17 and S16. We conclude that the oxidation process fluctuated from low to medium throughout this interval, and dinoflagellate cyst recovery was generally good.

4.2.2.2. Dinoflagellate cyst interval B (S15-S14). A remarkable drop in the

Homotryblium group (2-3%) is noticed in this interval which is characterized by common to superabundance of Cribroperidinium spp. (20.7-50%) and Wetzeliella spp. (4.4-24.6%) and abundant Spiniferites group (12-24.7%). Other dinoflagellate cyst taxa

(Batiacasphaera spp., Chiropteridium spp., Cordosphaeridium spp., Glaphyrocysta spp.,

Hystrichokolpoma spp., Lejeunecysta group, Pentadinium spp., Operculodinium spp.) are rare to few or absent in some samples (0-7%). Cribroperidinium spp., Lejeunecysta group and Wetzeliella spp. are indicators of inner neritic environments with high nutrients availability (Pross and Schmiedl, 2002; Pross et al., 2010; Soliman, 2012). The low percentage of Homotryblium group in interval B compared to its superabundance in intervals A and C (Fig. 5) is considered a very distinctive event. It may be indicative of a transitional environmental before the large-scale hiatus event between the Early Oligocene and the Early Miocene time. Furthermore, the high percentages of Cribroperidinium spp and Wetzeliella spp. may suggest a strong upwelling period. The upwelling is generally

252 accompanied by cold water conditions, which may affect the decline in the Homotryblium group that is abundant in warm water conditions. The presence of other dinoflagellate cysts and their ecological interpretations discussed in the previous sections further support this paleoenvironment interpretation.

The palynofacies analysis for the two samples represented in this interval indicates higher abundance of AOM (44.5-65.5%) than opaque phytoclasts (5-46.5%) and high percentages (8-28%) of marine palynomorphs (mainly dinoflagellate cysts). The preservation of dinoflagellate cysts in sample S15 is better than that in S14; there was probably less oxidation level as inferred from the low percentage of opaque phytoclasts.

4.2.2.3. Dinoflagellate cyst interval C (S13-S8). The Homotryblium group returns to dominance in interval C (15-67%), which also has high percentages of the Spiniferites group (13-45%). Other dinoflagellate cyst species and groups in this interval include

Batiacasphaera spp. (0.9-2%), Chiropteridium spp. (1-2.8%), Cordosphaeridium spp. (1-

2.3%), Cribroperidinium spp. (0.7-1.8%), Glaphyrocysta spp. (7.5-18%),

Hystrichokolpoma spp. (0.5-19%), Lejeunecysta group (0.7-7.8%), Pentadinium spp. (0.7-

14%), and Operculodinium spp. (0.5-38.57%). No representatives of Wetzeliella spp. are recorded in this interval. The dinoflagellate cyst assemblage is more similar to that of interval A, although there are slight differences in the percentages of some taxa. The increase in the percentages of the Glaphyrocysta group and Hystrichokolpoma spp. and the abundance of the Operculodinium and Spiniferites may be indicative of a fluctuation in the environment from restricted marine to high energy, open marine environment (Brinkhuis and Zachariasse, 1988; Köthe, 1990; Soliman, 2012). The consistent occurrence of the

Lejeunecysta group indicates high nutrients availability. This fluctuation is prominent

253 throughout the interval and is supported by the phosphate and dolomite distributions throughout the Arcadia Formation (Brewster-Wingard et al., 1997).

The palynofacies analysis shows a superabundance of AOM over the opaque phytoclasts, although a superabundance of the opaque particles (80%) vs. rare occurrence of AOM (4%) is observed in sample S13 in the bottom of this interval (Fig. 6). This sample is considered as the first sample representing the Early Miocene (see section 4.1.3), whereas the underlying samples S15 and S14 (dated as Early Oligocene) in interval B show superabundance of AOM (44.5-46%) vs. low percentage of opaque phytoclasts (5-46.5%).

This high fluctuation in the POM indicates a sudden change in the environment that further supports the hiatus event between the Early Oligocene and Early Miocene. An increase in the fungal remains noted in sample S8 is likely due to contamination during sample processing in the laboratory because of its very light color. Another possibility is that these fungal spores were growing in the core boxes since the well was drilled more than 25 years ago.

4.2.3. Palynofacies Interval 3, S5-S1. Opaque phytoclasts are superabundant (64-

77%) compared to AOM (10-30.7%) in the lower three samples (S5-S3). In samples S2 and S1, the opposite occurs with a decline in opaques (17-30%) vs. an increase in AOM

(62-74.6%). Marine palynomorphs have low percentages (1.5-10%) compared to interval

2 and are represented by foraminiferal test linings; no dinoflagellate cysts were recorded.

Based on the discussion in section 4.2.1 about the factors that may cause the increase in opaque phytoclasts, we attribute the high percentages of opaque phytoclasts to post depositional alteration. Diagenesis is indicated by alteration of limestone to dolostone

(Table 2).

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Plate I. Photomicrographs no 1 of dinoflagellate cysts. A. Achomosphaera grallaeformis. Left lateral view, mid focus, S15, EF G17/2. B. Batiacasphaera explanata. Uncertain view, mid focus, S18, EF F39/2. C. Brigantedinium? spp., Right lateral view, high focus, S10, EF C34/1. D. Chiropteridium galea. Dorsal view, high focus, S19, EF L31/2. E. Cleistosphaeridium ancyreum. Uncertain view, mid focus, S19, EF U44. F. Caligodinium pychnum. Uncertain view, mid focus, S11, E20. G. Cordosphaeridium cantharellus. Dorsal view, mid focus, S15, EF O20/3. H. Cordosphaeridium fibrospinosum. Dorsal view, low focus, S19, EF M27

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Plate II. Photomicrographs no 2 of dinoflagellate cysts. A-B. Cribroperidinium spp. A. Ventral view, low focus, S15, EF O20/3. B. Dorsal view, low focus, S18, EF K52. C-D. Deflandrea phosphoritica. C. Dorsal view, mid focus, S19, EF H46. D. Dorsal view, low focus, S24, EF O48/2. E-F. Diphyes colligerum. E. Right lateral view, low focus, S20, EF N24. F. Uncertain view, low focus, S24, E33/1. G. Dapsilidinium pseudocolligerum. Uncertain view, low focus, S19, EF L46/3. H. Eocladopyxis peniculata. Uncertain view, mid focus, S15, EF U28/3.

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Plate III. Photomicrographs no 3 of dinoflagellate cysts. A-B. Glaphyrocysta spp. A. Ventral view, high focus, S10, EF F44/3. B. Dorsal view, high focus, S12, EF K37/2. C-D. Hemiplacophora semilunifera. C. Dorsal view, mid focus, S24, EF N45/3. D. Opercular piece or fragment of a specimen, high focus, S24, EF Q28. E. Heteraulacacysta campanula. Uncertain view, mid focus, S11, EF N20/3. F. Homotryblium plectilum Uncertain view, high focus, S19, H46/2. G. Homotryblium vallum. Apical view, high focus, S10, EF K24/3. H. Hystrichokolpoma rigaudiae. Dorsal view, high focus, S11, EF R25. I. Kallosphaeridium biornatum. Apical view, mid focus, S14, EF M24/3. J-L. Lejeunecysta spp. J. Dorsal view, high focus, S11, EF V33/4. K. Dorsal view, low focus, S18, EF W46/1. L. Dorsal view, high focus, S18, EF P38.

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Plate IV. Photomicrographs no 4 of dinoflagellate cysts. A. Lingulodinium machaerophorum. Apical view, low focus, S20, EF M37. B. Lingulodinium multivirgatum. Apical view, high focus, S13, EF H29/1. C-D. Membranilarnacia? picena. C. Uncertain view, high focus, S12, EF O42. D. Closeup view of the processes showing the veil like ectophragm, mid focus, S12, EF O48. E-G. Pentadinium granulatum. E. Ventral view, high focus, S12, EF K42. F. Uncertain view, low focus, S12, P22/4. G. Uncertain view, mid focus, S12, EF K31/1. H. Operculodinium sp. Left lateral view, high focus, S24, EF B46. I. Selenopemphix nephroides. Apical view, low focus, S18, EF Q22/3. J-L. Spiniferites spp. J. Spiniferites pseudofurcatus. Left lateral view, high focus, S12, EF R34/1. K. Spiniferites mirabilis. Uncertain view, high focus, S15, EF H19. L. Spiniferites sp. Dorsal view, high focus, S19, EF P39/2.

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Plate V. Photomicrographs no 5 of dinoflagellate cysts. A. Tuberculodinium vancampoae. Uncertain view, mid focus, S13, EF U36. B. Wetzeliella gochtii. Uncertain view, mid focus, S15, EF J32/1. C-D. Acritarch sp. (Artemisiocysta cladodichotoma). C. mid focus, S14, EF H30/3. D. mid focus, S14, EF X23/3. E. Amorphous organic matter. S19, EF H20/1. F. Opaque particle, S24, L49/3. G-H. Planispiral microforaminiferal inner test lining. G. S10, EF N45. H. S24, EF L31/1. I. Degraded phytoclast particles, S21, EF H42/4. J. Pollen grain (Chenopodipollis sp.). S11, EF U36

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5. CONCLUSIONS

(1) Important dinoflagellate cyst bioevents allow us to propose the following age

assignments from the bottom to the top of the studied section in W-17001: sample

S24 to the Priabonian, samples S20-S14 to the Rupelian, and samples S13-S8 to

the Aquitanian. Two barren intervals of palynomorphs are noted; one occurs in the

lower part of the section (samples S23-S21), and another is represented by samples

S7-S1 in the upper part of the section.

(2) Two hiatus events are observed. The first hiatus event is indicated by the recovery

of Aquitanian marker dinoflagellate cyst species in sample S13 overlying Rupelian

or early Chattian? taxa in sample S14. Therefore, late Chattian sediments are

missing due to a hiatus event in the Arcadia Formation. A second hiatus event is

observed in the Aquitanian and is marked by the LOs of several dinoflagellate cyst

taxa in sample S10.

(3) Constrained cluster analysis of particulate organic matter allowed us to divide the

studied section into three palynofacies intervals (interval 1-interval 3) from the

bottom to the top of the section. Each of these intervals is marked by alternations

between the dominant two components, amorphous organic matter and opaque

phytoclasts.

(4) Constrained cluster analysis of dinoflagellate cysts in the productive middle part of

the studied section (S19-S8), in addition to sample S24 at the bottom of the section

yield three dinoflagellate cyst intervals (interval A-interval C) upsection.

260

(5) Dinoflagellate cyst intervals A and C are characterized by superabundances of the

Homotryblium group and occurrences of other inner neritic dinoflagellate cysts

indicating general shallowing conditions. Dinoflagellate cyst interval B is marked

by abundances to superabundances of Cribroperidinium spp. and Wetzeliella spp.

and a remarkable decline in the Homotryblium group. These dinoflagellate cysts

support inner neritic environment with high nutrient availability.

ACKNOWLEDGMENTS

We acknowledge the Department of Geosciences and Geological and Petroleum

Engineering, Missouri University of Science and Technology for funding this study. We thank the Florida Geological Survey for providing the samples for this study and extend our appreciation to Dr. Lucy Edwards for suggesting this project. Special thanks to Jesse

Hurd of the Florida Geological Survey for his great help and suggestions about processing the samples.

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SECTION

2. CONCLUSIONS

The Paleogene-Early Neogene time interval in four boreholes located in low and mid latitude regions was studied for palynological contents. Three of these boreholes are located in the eastern Equatorial Atlantic in the Côte d’Ivoire-Ghana Transform Margin and Nigeria, while the fourth borehole is located in southeastern Florida. One hundred and five samples were obtained from the Paleocene-Early Eocene interval and the Late Eocene-

Early Miocene interval. Comprehensive analysis of dinoflagellate cysts was achieved on all the samples and palynofacies analysis was conducted on some of them.

In Ocean Drilling Program (ODP) Site 959 (Hole 959D) in the Côte d’Ivoire-Ghana

Transform Margin, five dinoflagellate cyst biozones were erected for the Paleocene-Early

Eocene interval. The concentration of several last and first occurrences in the Late

Paleocene suggests a hiatus event. Furthermore, an outer neritic paleoenvironment was proposed and four new species were formally named. These new species have unique morphological characteristics with mostly short time intervals that indicate their importance for biostratigraphic correlation.

Four dinoflagellate cyst biozones were established for the Paleocene-Early Eocene interval in Alo-1 Well in the northern Niger Delta (Anambra) Basin, Nigeria. Unlike ODP

Hole 959D, the dinoflagellate cyst assemblage supports an inner neritic paleoenvironment.

Two new species were formally named.

In ODP Hole 959A, a new age assignment of Late Eocene was proposed for subunit

IIB. Five dinoflagellate cyst biozones were established for the Late Eocene-Early Miocene

268 interval and new biostratigraphic ranges were observed for two dinoflagellate cyst species.

Compared to ODP Hole 959D and Alo-1 sections, a deeper paleoenvironment with relatively cold-water masses during the Early Oligocene and hyperstratified conditions was inferred. Additionally, a hiatus event was noted upsection.

The dinoflagellate cyst data and palynofacies analysis of W-17001 in southeastern

Florida indicate two hiatus events and a fluctuation between a restricted paleoenvironment to open marine paleoenvironment. The dinoflagellate cyst taxa suggest a Late Eocene-

Early Miocene age with the absence of part of the Late Oligocene sediments.

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VITA

Walaa Awad was born in Egypt. She received her Bachelor of Science degree in geology in 2004 from the Geology Department at Alexandria University, Eygpt. Walaa completed her PhD degree in geology and geophysics in the Department of Geosciences and Geological and Petroleum Engineering at the Missouri University of Science and

Technology in May 2018. She worked as a graduate teaching and research assistant at

Alexandria University from 2004 to 2008. She was also a graduate teaching assistant at

Missouri University of Science and Technology from 2014 to 2017.