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Upper Campanian-Maastrichtian foraminifers of the high southern latitudes: Ontogenetic morphometric systematica, biostratigraphy, and paleobiogeography

Huber, Brian Thomas, Ph.D.

The Ohio State University, 1988

UMI 300 N. Zeeb Rd. Ann Arbor, MI 48106 UPPER CAMPANIAN-MAASTRICHTIAN FORAMINIFERS OF THE HIGH SOUTHERN

LATITUDES: ONTOGENETIC HORFHOMETRIC SYSTEMATICS,

BIOSTRATIGRAPHY. AND PALEOBIOGEOGRAPHY

DISSERTATION

Presented in Partial Fulfillment of the Requirements for

the Degree of Doctor of Philosophy in the Graduate

School of The Ohio State University

Brian Thomas Huber, B.S., M.S.

******

The Ohio State University

1988

Dissertation Committee: Approved by

P .-N. Webb W.I. Ausich S.M. Bergstrom e-^ L.A. Krissek Aai^sor Department of Geology and Mineralogy Copyright by Brian Thomas Huber 1988 In memory of ray grandfather, Arleigh J. Browand,

for his love of Nature's splendor

and his drive to achieve.

ii ACKNOWLEDGEMENTS

I anil very grateful to Peter-N. Webb for presenting me with many research opportunities during my graduate career at The Ohio State

University and for his continuous support and guidance. Peter-N.

Webb, William I. Ausich, Stig M. Bergstrom and Larry A, Krissek are thanked for critically reviewing this text and for their many helpful suggestions. 1 also owe thanks to David H. Elliot and Enriqueta

Barrera for many enlightening discussions and helpful comments. David

M. Harwood and Scott E. Ishman are acknowledged for pouring through rough drafts of past manuscripts and Chapter I of this dissertation.

To the fellow "Webb Boys", David M. Harwood, Scott E. Ishman, Charles

P. Hart, Reed H. Scherer, and Enriqueta Barrera, I am grateful for our many enjoyable conversations (science- related and otherwise) in the corridors of second floor Orton Hall and I look forward to our continuing association. Matt Karrer and Martin Marks are due thanks for their help processing samples in the wet lab. Finally, I am indebted to Kathleen Mullaney, for her help creating order out of chaos, her friendship and her encouragement.

Financial support for my research from the American Association of

Petroleum Geologists, Sigma Xi, the Geological Society of America, The

Friends of Orton Hall, the Byrd Polar Research Center, and the Ocean

Drilling Program is gratefully acknowledged. - I have also benefitted

iii from fellowship support from AMOCO Oil Co. and The Ohio State

University and Research Assistantships from National Science foundation Grants DPP-8214174*A01 and DPP-8517625A01.

iv ABSTRACT

Foraminifers from upper Campanian-Maastrichtian shelfal marine and deep sea sections at several high latitude sites in the Southern

Hemisphere are analyzed to improve biostratigraphic correlation with

low latitude reference sections and to reconstruct the paleoceanographic and paleoclimatic history of the circum-Antarctic region. New morphometric techniques are used to characterize the developmental morphologies of several Upper Cretaceous planktonic foraminifer taxa to better determine their taxonomic classification. Material used in this study is from Ocean Drilling Program (ODP) Sites 689 and 690

(Maud Rise), ODP Sites 698 and 700 (Northeast Georgia Rise), Deep Sea

Drilling Project Sites 327 and 511 (Falkland Plateau), and the James

Ross Island region (Antarctic Peninsula). Comparisons are also made with ODP Sites 738 and 750 (Kerguelen Plateau), DSDP Site 208 (Tasman

Sea), New Zealand and Western Australia.

Distinctive similarities among nearshore benthic and open ocean planktonic foraminifer assemblages from the southern South Atlantic and southern southwest Pacific regions suggest the presence of shallow marine seaways within West Antarctica during the Late Cretaceous.

Occurrence of recycled Cretaceous marine microfossils at numerous

Antarctic localities also argues for the former presence of intra-

Antarctic marine basins. Plots of poleward changes in total and keeled planktonic species diversity in the Southern Hemisphere are compared for the Campanian-Maastrichtian time periods. Latitudinal diversity gradients are weakest during the early Campanian and become more pronounced during the late Campanian and early Maastrichtian.

Five planktonic species endemic to the Austral Province first appear during the late Campanian and the early Maastrichtian, Progressive biogeographic isolation of Austral Province assemblages is inferred to reflect development of a major watermass boundary separating cool surface waters south of about 50°S paleolatitude from warmer surface waters to the north. An influx of thermophilic planktonic foraminifers, including both keeled and non-keeled forms, to the high southern latitudes occurred during the late Maastrichtian. This may have been caused by a temporary poleward expansion of the Tethyan

Province and a concommittant enhancement of surface water stratification.

vi VITA

July 20, 1959 ...... Born - Medina, Ohio

1977...... Diploma, Medina High School, Medina, Ohio

1981...... B.S., Geology, University of Akron, Akron, Ohio

1981-1984 ...... Research Assistant, Upper Cretaceous foraminifer biostratigraphy and paleoecology of the Antarctic Peninsula and southern South America

1984...... M.S. , Geology, biostratigraphy and micropaleontology, The Ohio State University, Columbus, Ohio

1984-1988 ...... Research Assistant and Graduate Fellow, Upper Cretaceous foraminifer biostratigraphy, paleoecology, paleobiogeography and paleoceanography of the high southern latitudes. Department of Geology and Mineralogy and Byrd Polar Research Center, The Ohio State University

1988...... Shipboard foraminifer paleontologist, Ocean Drilling Program Leg 119, southern Indian Ocean

1988...... Ph.D., Geology, biostratigraphy and paleoceanography, The Ohio State University, Columbus, Ohio

FIELD OF STUDY

Major Field: Geology

vii RESEARCH PUBLICATIONS

Huber, B.T. and P.N. Webb, 1986. Distribution of Frondicularla rakauroana Finlay in the southern high latitudes: Journal of Foraminiferal Research, 16(2):135-140.

Barrera, E., B.T. Huber, S.M. Savin and P.N. Webb. Antarctic marine temperatures; late Campanian through early Paleocene: Paleoceanography, 2(1):21-47.

Huber, B.T, Upper Campanian-Paleocene foraminifera from the James Ross Island region, Antarctic Peninsula: Id Feldmann, R.M. and M.O. Woodburne (eds.), Geology and Paleontology of Seymour Island, Antarctic Peninsula, Geological Society of America, Memoir Series 169, 163-252.

Huber, B.T., In press. Foraminiferal biogeography of the Late Cretaceous southern high latitudes: Fifth Symposium on Antarctic Earth Sciences, M.R.A. Thomson (ed.), Cambridge University Press, Cambridge.

Macellari, C.E., R.A. Askin and B.T. Huber, in press. El limits Cret&cico/Tertiario en la Peninsula Antarctica: X Congreso GeolOgico Argentino, Tucuman, Sept. 1987.

Macellari, C.E. and B.T. Huber, 1982. Cretaceous stratigraphy of Seymour Island (East Antarctic Peninsula): Antarctic Journal of the United States, 17(5):68-70.

Huber, B.T., D.M. Harwood and P.N. Webb, 1983. Upper Cretaceous microfossil biostratigraphy of Seymour Island, Antarctic Peninsula: Antarctic Journal of the United States, 18(5):72-74.

Huber, B.T., 1985. The location of the Cretaceous-Tertiary contact on Seymour Island, Antarctic Peninsula: Antarctic Journal of the United States, 20(5):46-48.

Huber B.T., 1986. Foraminiferal distribution across the Cretaceous/Tertiary boundary on Seymour Island, Antarctic Peninsula: Antarctic Peninsula: Antarctic Journal of the United States, 21(5):71-73.

Huber, B.T., in press. Ontogenetic morphometries of some Upper Cretaceous press foraminifera from the sothern high latitudes: Antarctic Journal of the United States, 22(5).

Huber, B.T., 1983. Upper Cretaceous foraminifera from Seymour Island, Antarctica: Geological Society of America, Annual Meeting, Abstracts with Programs, Indianapolis, Indiana, 15(6):600.

Huber, B.T., D.M. Harwood and P.N. Webb, 1985. Distribution of microfossils and diagenetic features associated with the

viii Cretaceous-Tertiary boundary on Seymour Island, Antarctic Peninsula: Abstract, Gwatt Conference on Rare Events in Geology, IGCP no. 199, May 20-22, Gwatt, Switzerland.

Huber, B.T., 1985. The distribution of Late Cretaceous, southern high latitude foraminifera and problems with correlation: Abstract, Workshop on Cenozoic Geology of the Southern High Latitudes, Aug. 16-17, Ohio State University, p. 18.

Barrera, E. and B.T. Huber, 1985, Seymour Island Campanian- Maastrichtian climate as inferred from foraminiferal isotope ratios and distributional analysis: Abstract, Workshop on Cenozoic Geology of the Southern High Latitudes, Aug. 16-17, Ohio State University, p. 6.

Huber, B.T., 1986a. Foraminiferal evidence for a terminal Cretaceous oceanic event: Geological Society of America, North Central Section Meeting, Abstract with Programs, Kent, Ohio, 18(4);309- 310.

Huber, B .T., 1986b. Foraminifera and the Cretaceous/Tertiary transition on Seymour Island, Antarctica: Geological Society of America, Annual Meeting, Abstracts with Programs, San Antonio, Texas, 18(6):642.

Barrera, E. and B.T. Huber, 1986. Seymour Island Campanian- Maastrichtian climate: foraminiferal isotopic and distributional evidence: Abstract, Second International Conference on Paleoceanography, September 6-13, Woods Hole, Massachussetts, p. 12.

Huber, B. T. and P.N. Webb, P.F. Barker, J.P. Kennett and Shipboard Scientific Party, 1987. Upper Cretaceous planktonic foraminifera from the Weddell Basin (ODP Leg 113): Geological Society of America, Annual Meeting, Abstracts with Programs, Phoenix, Arizona, 19(6):709.

Huber, B.T., in press. Evolutionary rates and taxonomic diversity among Upper Cretaceous foraminifera from the southern high latitudes: Origins and Evolution of the Antarctic Biota, Geological Society of London, May 15-18, 1988.

ix TABLE OF CONTENTS

TITLE PAGE...... 1

DEDICATION...... II

ACKNOWLEDGEMENTS...... iii

ABSTRACT...... v

VITA...... vii

TABLE OF CONTENTS...... x

LIST OF TABLES...... xv

LIST OF FIGURES...... xvi

LIST OF PLATES...... xxiv

LIST OF APPENDICES...... xxxi

CHAPTER I: INTRODUCTION ...... 1 PROBLEMS WITH HIGH SOUTHERN LATITUDE BIOSTRATIGRAPHY ...... 5 INFERENCES ON CRETACEOUS CLIMATE ...... II OXYGEN ISOTOPE PALEOTEMPERATURES ...... 13 CRETACEOUS PLANKTONIC FORAMINIFER DISTRIBUTIONS .... 18 CRETACEOUS CLIMATE MODELS ...... 22 MAJOR OBJECTIVES...... 23 PLAN OF S T U D Y ...... 24

CHAPTER II: ONTOGENETIC MORPHOMETRICS OF SOME UPPER CRETACEOUS PIANKTONIC FORAMINIFERS FROM THE HIGH SOUTHERN LATITUDES...... 27 ABSTRACT...... 27 INTRODUCTION ...... 28 MATERIALS ...... 37 APPROACH TO S T U D Y ...... 38 SAMPLE PREPARATION ...... 38 EXTERNAL MORPHOLOGY ...... 42 CONTACT MICRORADIOGRAPHY ...... 42 Methods ...... 42 Morphometric Parameters ...... 43 SERIAL DISSECTIONS ...... 44

x M e t h o d s ...... 44 Morphometric Parameters ...... 47 CRITERIA FOR TAXONOMIC CLASSIFICATION ...... 49 CONVENTIONAL CLASSIFICATION SCHEMES ...... 49 ONTOGENETIC MORPHOLOGY ...... 51 MORPHOMETRIC PARAMETERS ...... 57 Results from Test Exterior Observations .... 57 Utility and limitations...... 57 Ultimate whorl chamber number ...... 58 Coiling direction frequencies ...... 60 Kummerforrn frequencies ...... 61 Test breadth/diameter ratios ...... 62 Aoertural height/width ratios ...... 63 Position of the generating curve ...... 63 External ornamental features ...... 63 Results of Microradiograph Observations .... 66 Utility and limitations...... 66 Penultimate whorl chamber number ...... 67 Penultimate/antepenultimate chamber ratios 68 Results from Serial Dissection Observations . . 68 Utility and limitations...... 68 Froloculus diameters ...... 69 Initial whorl diameter...... 75 Initial whorl chamber number...... 78 Ontogenetic growth curves...... 79 SEM observations...... 88 DISCUSSION...... 89 ONTOGENETIC STAGES ...... 89 PALEOENVIRONMENTAL INFERENCES ...... 92 TAXONOMIC NOTES ...... 96 HEDBERGELLA SLITERI N. SP...... 96 COSTELLAGERINA BULBOSA (BELFORD) ...... 97 ARCHAEOGLOBIGERINA AUSTRALIS N. SP...... 103 ARCHAEOGLOBIGERINA CF. AUSTRALIS N. SP...... 105 ARCHAEOGLOBIGERINA BOSOUENSIS PESSAGNO ...... 105 ARCHAEOGLOBIGERINA MATEOLA N. SP...... 106 GLOBOTRUNCANA CRETACEA (D'ORBIGNY) ...... 107 RUGOGLOBIGERINA RUGOSA (PLUMMER) ...... 108 CONCLUSIONS ...... 109

CHAPTER III: MAESTRICHTIAN PLANKTONIC FORAMINIFERS FROM THE MAUD RISE (SOUTHERN SOUTH ATLANTIC), OCEAN DRILLING PROGRAM LEG 113 126 ABSTRACT...... 126 INTRODUCTION ...... 127 METHOD OF S T U D Y ...... 130 FORAMINIFER BIOSTRATIGRAPHY ...... 131 HOLE 6 8 9 B ...... 131 HOLE 6 9 0 C ...... 137 AGE DETERMINATIONS...... 143 ZONAL S C H E M E ...... 148 Globigerinelloides impensus Total Range Zone . . . 151

xi Clobotruncanella havanensls Interval Zone...... 151 Abathomphalus mavaroensls Total Range Zone .... 151 CORRELATION OF HIGH SOUTHERN LATITUDE SITES ...... 152 PALEOBIOGEOGRAPHY...... 153 THE AUSTRAL BIOGEOGRAPHIC PROVINCE ...... 153 PALEOENVIRONMENTAL INFERENCES ...... 156 SYSTEMATIC DESCRIPTIONS ...... 159 GUEMBELITRIA CRETACEA CUSHMAN ...... 159 HETEROHELIX GLABRANS (CUSHMAN) ...... 160 HETEROHELIX GLOBUIILSA (EHRENBERG) ...... 160 HETEROHELIX PULCHRA (BROTZEN) ...... 160 GUBLERINA COMPRESS A (VAN DER SLUIS) ...... 160 GLOBIGERINELLOIDES ALVAREZI (ETERNOD OLVERA) ...... 161 GLOBIGERINELLOIDES IMPENSUS SLITER ...... 161 GLOBIGERINELLOIDES MULTISPINATUS (LALICKER) ...... 162 GLOBIGERINELLOIDES SUBCARINATUS (BRONNIMANN) ...... 162 SCHACKOINA MULTISPINATA (CUSHMAN AND WICKENDEN) . . . 162 HEDBERGELLA HOLMDELENSIS OLSSON ...... 163 HEDBERGELLA MONMOUTHENSIS (OLSSON) ...... 164 HEDBERGELLA SLITERI N. SP...... 164 ARCHAEOGLOBIGERINA AUSTRALIS N . SP...... 167 ARCHAEOGLOBIGERINA MATEOLA N. SP...... 170 RUGOTRUNCANA CIRCUMNOPIFER (FINLAY) ...... 172 GLOBOTRUNCANELLA HAVANENSIS (VOORWIJK) ...... 173 CLOBOTRUNCANELLA PETALOIDEA (GANDOLFI) ...... 173 ABATHOMFHALUS INTERMEDIUS (BOLLI) ...... 174 ABATHOMPHALUS MAYAROENSIS (BOLLI) ...... 174 GLOBOTRUNCANA ARCA (CUSHMAN) ...... 175 GLOBOTRUNCANA SUBCIRCUMNODIFER (GANDOLFI) ...... 175 CONCLUSIONS ...... 176

CHAPTER IV: PLANKTONIC FORAMINIFER BIOSTRATIGRAPHY OF UPPER CAMPANIAN-MAESTRICHTIAN SEDIMENTS FROM ODP LEG 114, SOUTHERN SOUTH ATLANTIC ...... 191 ABSTRACT...... 191 INTRODUCTION ...... 192 METHOD OF S T U D Y ...... 200 BI OS TR A T I G R A F H Y ...... 201 HOLE 6 9 8 A ...... 201 Preservation ...... 207 Foraminifer Distributions ...... 207 HOLE 7 0 0 B ...... 210 Preservation ...... 213 Foraminifer Distributions ...... 216 Diversity T r e n d s ...... 219 Magnetochronologic Correlation ...... 219 DISCUSSION...... 220 TAXONOMIC NOTES ...... 226 GLOBIGERINELLOIDES IMPENSUS SLITER ...... 226 HEDBERGELLA MONMOUTHENSIS (OLSSON) ...... 226 HEDBERGELLA SLITERI N. SP...... 227 HEDBERGELLA SP...... 227

xii ARCHAEOGLOBIGERINA AUSTRALIS N. SP...... 227 ARCHAEOGLOBIGERINA MATEOLA N. SP...... 22 RUGOTRUNCANA CIRCUMNODIFER (FINLAY) ...... 228 GLOBOTRUNCANA ARCA (CUSHMAN)...... 229 GLOBOTRUNCANA LTNNEIANA (D'ORBIGNY) ...... 229 CLOBOTRUNCANELLA HAVANENSIS (VOORWIJK) ...... 229 GLOBOTRUNCANELLA PETALOIDEA (GANDOLFI) ...... 230 ABATHOMPHATUS MAYAROENSIS (BOLLI) ...... 230

CHAPTER V: PALEOBIOGEOGRAPHY OF CAMPANIAN-MAASTRICHTIAN FORAMINIFERS IN THE HIGH SOUTHERN L A T I T U D E S ...... 237 ABSTRACT...... 237 INTRODUCTION ...... 238 SOUTHERN HEMISPHERE PALEOCEOGRAPHY...... 239 CONTINENTAL DISTRIBUTIONS ...... 239 ANTARCTIC PALEOGEOGRAPHY ...... 241 CONSTRAINTS OF THE HIGH LATITUDE ENVIRONMENT...... 254 PLANKTONIC FORAMINIFER DEPTH STRATIFICATION ...... 256 MODERN SURFACE WATER DISTRIBUTIONS ...... 258 CRETACEOUS DEPTH STRATIFICATION ...... 259 PREVIOUS STUDIES OF THE CRETACEOUS SOUTHERN. EXTRA-TROPICAL BIOGEOGRAPHIC PROVINCE ...... 264 CAMPANIAN-MAASTRICHTIAN PLANKTONIC FORAMINIFER PALEOBIOG EO G R A P H Y ...... 268 METHODS AND APPROACH...... 268 FAUNAL PROVINCE DISTRIBUTIONS ...... 271 Early C a m p a n i a n ...... 279 Late Campanian...... 280 Early Maastrichtian...... 281 Late Maastrichtian...... 282 COMPARISON WITH NORTHERN HEMISPHERE ASSEMBLAGES . . . 284 NEARSHORE BENTHIC FORAMINIFER PALEOBIOGEOGRAPHY ...... 286 INFERRED PATTERNS OF SURFACE CIRCULATION ...... 291 CONCLUSIONS ...... 295

REFERENCES...... 298

APPENDICES...... 314

xiii LIST OF TABLES

TABLE PAGE

Table 1. Morphometric data obtained from external observations and microradiographs of species discussed in this study. . . 59

Table 2. Morphometric and observational data obtained from planktonic foraminifer serial dissections...... 70

Table 3. Numerical abundance counts of planktonic foraminifers (totalling 300 specimens) and other biogenic constituents for Hole 698A...... 205

Table 4. Numerical and relative abundance counts of planktonic foraminifers and other biogenic constituents for ODP Hole 700B...... 214

Table 5. Site locations and age ranges for planktonic foraminifer species that are endemic to the Austral Province...... 222

Table 6. Locations, age ranges, inferred depositional environments, and inferred subglacial basin sources for marine and non-marine microfossils found in situ or reworked within or around the Antarctic continent...... 248

Table 7. Biogeographic province names for the extra-tropical region during the Cretaceous...... 266

Table 8. Campanian-Maastrichtian planktonic foraminifer species diversity for Southern Hemisphere deep sea and land-based sites. The number of keeled species is plotted in parentheses next to the total number of species per site. 272

Table 9. Distribution and age ranges of benthic foraminifers restricted to several localities within the Austral Province. 289

xiv LIST OF FIGURES

FIGURES

Figure 1. Polar projection of Southern Hemisphere continents showing the locations of deep sea and nearshore sites yielding upper Campanian-Maastrichtian foraminifers that are discussed in this study. The positions of the Antarctic water mass and Antarctic Convergence are also portrayed. JRI — James Ross Island region......

Figure 2. Geologic map of the James Ross Island region showing the locations of Cretaceous through Tertiary outcrops of nearshore marine sediments. Foraminifers discussed in this study are from Cretaceous sediments of the Lopez de Bertodano Formation on Seymour Island. (From Huber, 1988.) ......

Figure 3. Late Cretaceous paleogeographic reconstruction showing the high southern latitude distribution of the distinctive benthic foraminifer species Frondicularia rakauroana (Finlay). Arrows show possible communication routes for this species. la — Marlborough, New Zealand; lb - Southern Hawkes Bay, New Zealand; lc — Northland, New Zealand; 2 - Lord Howe Rise, DSDP Leg 21, Site 208; 3 - Seymour Island; 4 - Minilya Well no. 1, Carnarvon Basin, Australia. Reconstruction after Smith et al. (1981) for 80 Ma. (From Huber and Webb, 1986.)

Figure 4. Oxygen isotope paleotemperature curve (slightly modified from Douglas and Woodruff, 1981) based on analyses of planktonic and benthic foraminifers and calcareous nannoplankton from equatorial Pacific Deep Sea Drilling Project sites. Upper curve represents surface water paleotemperature estimates and bottom curve represents estimates for bottom water paleotemperatures. Note the decline in surface and bottom water temperatures shown from the early Campanian through the Maastrichtian (arrows). Plots compiled from Douglas and Savin (1973, 1975), Savin et al. (1975), and unpublished data (Douglas and Woodruff, 1981)......

Figure 6. Estimated range of temperatures (indicated by shaded area) of bottom shelf water and surface water at Seymour Island for each of the following intervals: a) late Campanian to early Maastrichtian, b) early to middle Maastrichtian, c) late Maastrichtian, and d) earliest Paleocene. Isotopic curves for each of the taxa are indicated as follows: squares, Cibicldes sevmouriensis: pluses, Anoma1inoides piripaua: diamonds, Lenticulina macrodisca: triangles, Dentalina baslplanata: crosses, Hoegludina supracretacea: inverted triangles, Globigerinelloides multisoinatus (planktonic species). From Barrera et al. (1987)...... 15

Figure 7. Curve from Krasheninnikov and Basov (1986) showing relative climatic fluctuations at the Falkland Plateau during the Cretaceous through Cenozoic in the southern South Atlantic, as inferred from planktonic foraminifer distributional data. The curves drawn for the Late Cretaceous were based on the number of keeled planktonic foraminifers present and total species diversity of assemblages from Deep Sea Drilling Project Sites 327 and 511. Suggestion that globotruncanid (keeled) species are absent from the South Atlantic high latitudes was made prior to recovery of upper Maastrichtian sections yielding diverse keeled assemblages. No upper Maastrichtian sediments have yet been recovered from the Falkland Plateau, where this study was based...... 19

Figure 8. An example of the conventional approach to classification of Upper Cretaceous planktonic foraminifers based on external morphocharacters. From Caron (1985, Fig. 1). 30

Figure 9. Morphometric parameters measured from external views of planktonic foraminifers. Apertural height:width ratios measured only on specimens showing extraumbilical apertures...... 39

Figure 10. Morphometric parameters measured from x-radiograph images. Initial whorl dimensions were only obtained on the most evolutely coiled specimens...... 40

Figure 11. Morphometric parameters measured from the initial whorl exposed after complete test dissection. The initial whorl chamber

xv i number is determined from the sequential count of chambers following the proloculus (P) to the point of overlap with the proloculus-deuteroconch (— first chamber) suture, recorded as 0.25 chamber increments......

Figure 12. Scatter plots and least squares regression of proloculus and initial whorl diameter measurements for seven Upper Cretaceous species of planktonic foraminifers. Host species show strong correlation between these two parameters. Note the wide scatter of points shown by juvenile specimens of Archaeoglobieerina australis and the strongly bimodal point distribution portrayed by Archaeoplobigerina mateola. Least squares regression line equation, correlation coefficient (r) and number of measured spesimens (n) are presented for each species......

Figure 13. Univariate plots of mean, 1 standard deviation about the mean, and total size range for proloculus and initial whorl diameters for the planktonic foraminifers analyzed in this study. Three population sets of Archaeoelobieerina australis were measured, including juvenile (juv.) and adult specimens from OSDP Site 511 and adult specimens from ODP Site 690. Fig. 5 shows the number of specimens measured for each species......

Figure 14. Bivariate plot of mean proloculus and initial whorl diameters for Upper Cretaceous planktonic foraminifers analyzed in this study. Globotruncana cretacea (d'Orbigny) shows much larger mean values than any of the other species and juvenile (juv.) specimens of Archaeoglob1 perina australis n, sp., from DSDP Site 511, show significantly lower values than adult specimens from DSDP Site 511 and ODP Site 690. See Figure 5 for the number of specimens measured of each species.to accurately characterize their ontenies. Mean values obtained for adult normalform and kummerform specimens of australis from the Falkland Plateau (DSDP Leg 71) are close to those obtained for Maud Rise (ODP Leg 113) specimens of the same species, indicating that this is a useful criterion for taxonomic comparisons......

Figure 15, Arithmetic and logarithmic plots of the chamber-by- chamber increase in cross-sectional chamber area of juvenile and adult specimens of Archaeogloblgerlna australis n. sp. from DSDP Leg 71 and adult specimens from ODP Leg 113. The arithmetic plots show 1 standard deviation about the mean and the logarithmic plots show only the mean values. The number (n) of specimens analyzed are also shown......

Figure 16. Arithmetic and logarithmic plots as in Fig. 8 for three Upper Cretaceous planktonic foraminifer species. Smaller standard deviation values for the 16th chambers of

xvii Archaeoglobigerina roateola and £. cretacea results from fewer number of measurements rather than actual population trend.

Figure 18. Mean logarithmic values of the chamber-by-chamber increase in cross-sectional chamber areas of all Upper Cretaceous planktonic foraminifer species analyzed in this study. Changes in slope reflect ontogenetic changes In the rate of chamber size increase. Note the smaller value of the deuteroconch (#2 chamber) relative to the proloculus (#1 chamber). Data sets from measurement of adult specimens of Archaeoglobigerina australis n. sp. from DSDP Site 511 and ODP Site 690 ......

Figure 19. Logarithmic plots of cross-sectional chamber areas measured from one juvenile and two adult specimens of Archaeoglobigerina australis n. sp. from Sample 71-511-24- 5,69-71. Transition from the juvenile to adult stage for this species does not occur abruptly and may vary among different specimens. It is characterized by movement of the aperture from an extra-umbilical to umbilical position, decreasing axial test compression, and a decrease in the rate of chamber size increase. Note that the sequential chamber size is strongly controlled by the size of the prolocular (first) chamber......

Figure 20. Logarithmic plots of the mean cross-sectional chamber area of juvenile and adult specimens of Archaeoglobigerina australis n. sp. from DSDP Leg 71 and adult specimens from ODP Leg 113. Note that the Leg 71 and Leg 113 adult morphotypes compare closely in their mean values, but the mean values of the juvenile specimens diminishes particularly after the eighth chamber......

Figure 21. Phylogenetic reconstruction inferred for Upper Cretaceous planktonic foraminifer species discussed in this study based on results of ontogenetic comparisons. Rup.ot rune ana circumnodifer and Ma r g i no trunc ana pseudolinneiana Pessagno were not analyzed in this study; the phylogenetic link inferred for Rueotruncana and Rugoglobigerina is from Robaszynski et al. (1984). Ontogenetic study of G. cretacea suggests an marginotruncanid ancestral stock, rather than ancestral relationship with Whitenella. as proposed by Pessagno (1967) and Robaszynski et al. (1984)......

Figure 22. Paleogeographic map for the early Maestrichtian showing the regional setting of Maud Rise Sites 689 and 690

xviii and DSDP Sites 327 and 511. JRI refers to the James Ross Island region of Antarctic Peninsula. Small dots represent other DSDP and ODP sites drilled In the South Atlantic. Paleogeographlc reconstruction after Barron (1987)...... 128

Figure 23. Summary of the drilling recovery, llthology, planktonlc/benthic ratios, and planktonic foraminifer species diversity graphs for samples analyzed from the Cretaceous sequence of Hole 689B. These were taxonomically differentiated by family using the classification of Loebllch and Tappan (1988). Samples above Core 119-689B-27X were unavailable for this study...... 132

Figure 24. Distribution and relative abundance of upper Campanian through Maestrichtian planktonic foraminifers from Hole 689B. The plots are based on combined totals for 300 specimen counts of the >150 micron and <150 micron size fractions (Appendices A-B). Relative abundance rankings and planktonic foraminifer zones are shown at the bottom of the figure. . . 134

Figure 25. Summary of the drilling recovery, lithology, planktonic/benthic ratios, and planktonic foraminifer species diversity graphs for samples analyzed from the Cretaceous sequence of Hole 690C. These were taxonomically differentiated by family using the classification of Loebllch and Tappan (1988). Samples above the core-catcher of Core 119-690C-16X were unavailable for this study...... 138

Fignre 26. Distribution and relative abundance of upper Campanian through Maestrichtian planktonic foraminifers at Hole 690C. The plots are based on combined totals for 300 specimen counts of the >150 micron and <150 micron size fractions (Appendices C-D). Magnetostratigraphic information from Hamilton (in prep.). See Figure 24 for the key to relative abundance rankings and planktonic foraminifer zonal subdivisions...... 141

Figure 27. Correlation of southern South Atlantic and Tasman Sea deep sea sites based on the highest occurrence (T) of Globigerinelloides impensus. the first appearance (B) of Globotruncanella havanensis. and the highest occurrence of Abathomohalus mavaroensis. or absence of these species. All core-sections (numbered in boxes) are scaled to their stratigraphic thickness and those that have relatively complete Cretaceous-Tertiary boundaries are scaled from the top of the Cretaceous sediments...... 145

Figure 28. Comparison of zonal schemes developed for the planktonic foraminifer Tethyan and Transitional Provinces of the Southern Hemisphere with the scheme proposed in this study and the calcareous nannoplankton zonation of Wind and Wise (1983) for the Austral Province. 1Caron, 1985; 2Wright

xix and Apthorpe, 1976; 3Webb, 1971; 'Krasheninnikov and Basov, 1986; *Huber, 1988; *Wind and Wise, 1983...... 149

Figure 29. Map of the southern South Atlantic Ocean and Weddell Sea, showing the locations of ODP Sites 698 and 700 on the northeast Georgia Rise, ODP Sites 689 and 690 on the Maud Rise, and DSDP Sites 327 and 511 on the Falkland Plateau. The 3000 m bathymetric contour is also portrayed...... 193

Figure 30. Vertically exaggerated cross-section of the southern South Atlantic sea floor at about 5l°S showing the locations of ODP Sites 698 and 700...... 195

Figure 31. Correlation of Santonian through Maestrichtian deep sea sites in the southern South Atlantic based on recognition of the Globigerinelloides impensus Zone, G1obotruneane11a havanensis Zone, and Abathomohalus mavaroensls Zone, as defined in Chapter III...... 198

Figure 32. ODP Hole 698 lithostratigraphy, stratigraphic ranges of selected planktonic foraminifer and calcareous nannoplankton species, total and keeled planktonic foraminifer diversity plots, and planktonic/benthic foraminifer ratio plots. Calcareous nannoplankton plots based on data from Crux (is Ciesielsk, et al., in press). . 202

Figure 33. ODP Hole 700B lithostratigraphy, magnetostratigraphy, stratigraphic ranges of selected planktonic foraminifer and calcareous nannoplankton species, total and keeled planktonic foraminifer diversity plots and planktonic/benthic foraminifer ratio plots. Calcareous nannoplankton distributions based on data from Crux (In Ciesielski et al., in press)...... 211

Figure 34, Paleogeographic reconstruction map showing the clrcum- Antarctic distribution of upper Campanian-Maestrichtian planktonic foraminifer species that are endemic to the Austral Province. Continental distributions are based on a reconstruction for 80 Ma by Smith et al. (1981). The paleogeography of South America and Africa are from a reconstruction of Barron (1987) for the early Maestrichtian. The basis for reconstruction of Antarctic land-sea distributions is discussed in Chapter V ...... 223

Figure 35. Paleogeographic reconstruction map for 80 Ma (after Smith et al., 1981) showing locations of land-based and deep sea sediments within the Cretaceous Austral Province that yield in situ marine invertebrates, including foraminifers (bold numbered sites 1-6, 9-14) and molluscs (bold numbered sites 1-8). Sites yielding reworked Cretaceous marine and terrestrial microfossils are also shown (bold numbered sites

xx 15-20). In situ terrestrial microfossils were found at locality 21. 1 - James Ross Island region; 2 *■ southern Chile; 3 - southern Argentina; 4 - New Zealand; 5 - Great Artesian Basin; 6 - Otway Basin; 7 — Alexander Island; 8 - South Georgia; 9 - Falkland Plateau (DSDP Sites 327A and 511); 10a - Weddell Basin ODP Leg 113 (Sites 689, 690); 10b - Weddell Basin, ODP Leg 113 (Sites 692, 693); 11 - ODP Leg 114 (Sites 698 and 700); 12 - Lord Howe Rise DSDP Leg 21 (Site 208); 13 - Burdwood Bank; 14 - Kerguelen Plateau ODP Legs 119 and 120 (Sites 738, 748, 750); 15 - King George Island; 16 - Taylor Valley; 17 - Transantarctic Mountains; 18 - Weddell Basin; 19 - Ross Sea DSDP Leg 28 (Site 270); 20 - Prydz Bay ODP Leg 119 (Sites 739, 741); 21 — Operation Deep Freeze Core 38. Italicized numbers refer to Southern Hemisphere DSDP sites yielding Upper Cretaceous foraminifers. See text for references...... 242

Figure 36. Stratigraphic ranges of Cretaceous land-based, deep- sea, and recycled marine sediments recovered from within the Austral Province. Numbers in parentheses correspond to site locations shown in Fig. 35...... 244

Figure 37. Subglacial topography map after Drewry (1983) showing the location of major subglacial basins inferred to be site of sediment deposition during the non-glacial past...... 251

Figure 38. a). Typical density/depth profiles for modern low and high latitude oceans showing differences in surface water stratification (from Pond and Pickard, 1984). 257

Figure 39. Life cycles and depth stratification inferred for modern and Cretaceous shallow, intermediate, and deep water planktonic foraminifera. From Caron and Homewood, 1983. . . 260

Figure 40. Diagrammatic portrayal of factors influencing the depth habitats of Upper Cretaceous planktonic foraminifera. The poleward loss of stenothermal, keeled (deeper dwelling) morphotypes may have been related to a concomitant shallowing of the photic zone (due to decreasing insolation angle and increased seasonality). Note the poleward reduction In meridional ornament on the figured rugoglobigerine morphotypes...... 262

Figure 41. Diversity plots of total (squares) and keeled (crosses) planktonic foraminiferal species diversity in the Southern Hemisphere for the early and late Campanian and the early and late Maestrichtian. The boundaries between the Late Cretaceous Southern Hemisphere biogeographic provinces are designated by a dashed line. Sites listed in Table 8 have been adjusted to their Late Cretaceous paleolatitudes. 273

xxi Figure 42. Paleogeographic reconstruction showing continental and land-sea distributions for the early and late Campanian. Areas inferred to be above sea level are shown by the stippled pattern. Planktonic foraminifer species diversity is plotted according to paleolatitude positions of sites listed in Table 8. Inferred paleobiogeographic boundaries between the Tethyan, Transitional, and Austral Provinces are delimited by dashed lines. Continental distribution data from Smith et al. (1981) and Veevers (1984). Information on land-sea distributions in Antarctica based on the sublacial topography map of Drewry (1983) and paleobiogeographic distributions discussed in the text. Other land-sea distributions based on the reconstruction for the early Maastrichtian from Barron (1987)...... 275

Figure 43. Paleogeographic reconstruction showing continental and land-sea distributions for the early and late Maastrichtian. See Fig. 42 for additional information...... 277

Figure 44. Biostratigraphic zonal schemes for Upper Cretaceous nearshore sites in New Zealand, southern South America and the Antarctic Peninsula, Hlebb, 1971; 2Bertels, 1979; 3Malumian and Masiuk, 1976; *Huber, 1988...... 287

Figure 45. Inferred patterns of surface circulation for the Southern Hemisphere during the Campanian through Maastrichtian. See Fig. 42 for explanation of paleogeographic reconstructions...... 292

xxii LIST OF PLATES

PLATE PAGE

Plate I. Upper Campanian-Maastrichtian planktonic foraminifers from southern, extra-tropical latitudes previously illustrated in Deep Sea Drilling Project reports. The taxonomic classification of these forms is revised in this study. Figs. 1-2. Hedbereella sliteri n, sp., previously identified as Hedbereella monmouthensis (Olsson) by Webb (1973b, PI. 3, Figs. 1-2) from south Tasman Sea DSDP Site 208. Figs. 3-5. Hedbereella sliteri n. sp., previously identified as Hedbergella holmdelensis Olsson by Sifter (1977, Pi. 2, Figs. 1-4) from the Falkland Plateau DSDP Site 327. Figs. 6, 10-11. Archaeogloblgerina australis n. sp. (juvenile form), previously identified as Hedbereella monmouthensis (Olsson) by Sliter (Pi. 3, Figs. 1-3) from Falkland Plateau DSDP Site 327. Figs. 7-9. Archaeoelobigerina australis n. sp. (juvenile form), previously identified as Hedbergella monmouthensis (Olsson) by Krasheninnikov and Basov (1983, PI. 6, Figs. 5, 7-8) from Falkland Plateau DSDP Site 511. Figs. 12-14. Archaeoglobigerina australis n. sp. (gerontic form), previously identified as Rugoelobigerina pjlula Belford by Sliter (1977, PI. 10, Figs, 7-9) from Falkland Plateau DSDP Site 327. Figs. 15-17. Archaeoglobigerina australis n. sp. (gerontic form), previously identified as Rugogloblperlna oilula by Krasheninnikov and Basov (1983, PI. I, Figs. 4-6) from Falkland Plateau DSDP Site 511. Figs. 18-20. Archaeoglobigerina australis n. sp. (gerontic form), previously identified as Rugoglobigerina pustulata Bronnimann by Krasheninnikov and Basov (1983, PI. 10, Figs. 10-12) from Falkland Plateau DSDP Site 511. Figs. 21-22, 26-27. Archaeoglobigerina australis n. sp. (gerontic form), previously identified as Rugoglobigerina rotundata Bronnimann by Krasheninnikov and Basov (1983, PI. I, Figs. 7-11) from Falkland Plateau DSDP Site 511. Figs. 23-25. Archaeoglobigerina australis n. sp. (gerontic form), previously identified as Rugoglobigerlna rotundata Bronnimann by Sliter (1977, PI. I. Figs. 1-3) from Falkland Plateau DSDP Site 327...... 33

Plate II. Juvenile, kummerform adult, and normalform adult planktonic foraminifers from Seymour Island (northern Antarctic Peninsula)

xxiii previously designated by Huber (1988, p. 207, Figs. 29.1-14, 30,5- 10) as Rugpglobigerina? sp. 1, but presently included in Archaeoelobigerina australis n. sp. Microradiographs of each specimen (Figs. 2, 6, 10) show the chamber arrangement in the penultimate and earlier whorls. Figs. 1-4. Juvenile form from sample 165. Figs. 5-8. Kummerform adult form from sample 165. Figs. 9-12. Normalform adult form from sample 415...... 35

Plate III. Serial dissections and x-radiographs of topotype specimens of Costellagerina pilula (Belford), Toolonga Calcilutite, Pillarawa Hill, Vestern Australia, sample 71640043. Figs. 1-4. Four chambered morphotype previously recognized as Costellagerina bulbosa (Belford) by Petters et al. (1983) and Rueogloblperina bulbosa Belford by Belford (1960) (216 pm). Figs. 6-10. Larger, 5.5 chambered morphotype (348 pm) . Figs. 11-13. Five chambered morphotype (288 pm). Morphologic similarity of the ontogenies revealed by serial dissection of the four, five and 5.5 chambered morphotypes suggests these are ecophenotypes of a single species. £. pilula is retained as the name bearer of these forms. . . 53

Plate IV. Juvenile and adult specimens of Rugoglobigerina rueosa (Plummer) from the upper Maastrichtian Kemp Clay (Texas) near the location from which this species was originally described. Figs. 1-5. Exterior, microradiograph and interior views of a juvenile specimens (220 pm) . The juvenile morphology is characterized by the poor development of meridional alignment of costellae on the antepenultimate and earlier chamber surfaces and the continuing rapid rate of chamber size increase in the final whorl. Fig. 6. Complete serial dissection of a Juvenile specimen (218 pm), Fig. 7. Enlarged view of a well developed tegillum on the Juvenile specimen shown in Figs. 1-5. Figs. 8-13. Exterior, microradiograph, and interior views of a adult specimen (424 pro). Note that the chambers in the final whorl show well developed meridional costellate ornamentation and a diminished rate of size increase. Figs. 14-15. Complete serial dissection of adult specimens. 14: 435 pm, 15: 414 pm. Note the somewhat renlform morphology of the initial whorl chambers. These initial whorl morphologies are identical to the juvenile morphology shown in Fig. 6...... 55

Plate V. Serial dissections and x-radiographs of species of Hedbergella. Figs. 1-3. Hedbereella holmdelensis Olsson, Redbank Formation, sample NJK-3, New Jersey (210 pm). Figs. 4-5, 9-10. Hedbergella sp., Redbank Formation, sample NJK-3, New Jersey (214 pm). Figs. 6-8. Hedbergella monmouthens is (Olsson), topotype from Redbank Formation, sample NJK-3 (170 pm). Figs. 11-18. external and internal views of Hedbergella sliteri n. sp., DSDP Site 327, Falkland Plateau. 11-13, 15: 236pm. 14: 282 pm. 16-17: 249 pm. 18: width of photo is 234 pm...... 112

X X iv 236pm. 14: 282 pm. 16-17: 249 pm. 18: width of photo is 234 pm...... 112

Plate VI. Specimens of Archaeoyloblperlna cf. australis n. sp. from lower Maastrichtian sediments on Seymour Island (Antarctic Peninsula). Figs. 1-7, 12. External and microradiograph views and serial dissections of a single specimen from sample 165, Note the similarity in external view to Rugoeloblgerlna rueosa. with the presence of meridionally aligned pustules on the penultimate chamber and an umbilical tegillum. Complete serial dissection of this specimen reveals an initial whorl morphology with little resemblence to E- ruposa. but identical morphology to randomly ornamented specimens of A. australis from the Maud Rise and Falkland Plateau. The initial whorl chambers in the Seymour Island specimen are more globular and Increase more rapidly in size than the initial whorl chambers of R. rueosa (301 pm). Figs. 8-11. External, microradiograph views of a juvenile form of australis n. sp., from sample 415 (208 pm)...... 114

Plate VII. Juvenile forms of Archaeoglohigerina australis n. sp. from sample 71-511-24-5,69-71, Falkland Plateau. Note variability in the prolocular and initial whorl dimensions and the number of chambers occurring in the initial whorl. Figs. 1-6. External and x-radiograph views and serial dissections (178 pm). Figs. 7-8. External view and complete dissection (170 pm). Figs. 9-10. Complete dissection and enlarged view of the initial whorl (181 pm). Figs. 11-13, External view and serial dissections (199 pm). Figs. 14-15. External view and complete dissection (202 pm). Figs. 16-19. Microradiograph and serial dissections (197 pm)...... 116

Plate VIII. Figs. 1-8. Kummerform juvenile specimens of Archaeogloblgerina australis n. sp. showing a higher number of initial whorl chambers than adult forms. 1-4, 7-8. Exterior and microradiograph views and serial dissections, Sample 71-511-23-4,67-69. Note the transition from a globigerine morphology in the penultimate whorl to a more axially compressed hedbergellid morphology in the initial whorl (265 pm). 5-6. Exterior view and complete dissection, Sample 71-511-23-4,67-69 (170 pm). Figs. 9-17. Kummerform specimens designated as &. mateola n. sp. lacking the strong spinosity typical of this species, but having similar internal morphologies. 9-12, 17. Exterior view and serial dissections, Sample 113-689B-28-3, 83-87 cm. Note the globigerine penultimate whorl morphology and very large proloculus (253 pm). 13-16. Note that this specimen has a very small proloculus (12 pm) and the test consists of more than three whorls (376 pm)...... 118

XXV Plate IX. Adult specimens of ArchaeoglobleerIna cf. A- australis n. sp. and Archaeoglobtgerina australis n. sp. Figs. 1-4, 10. Archaeoalobieerina cf. A- australis n. sp., Sample 71- 511-24-5,o9-71 (252 /xm). External view, microradiograph, and serial dissection of a specimen bearing faintly developed meridional costellae and a weak umbilical tegillum. The specimen was damaged during removal of the initial whorl chambers. Note the similarity in external features to A- cf- A. australis from Seymour Island (Pi. VI, Figs. 1-7, 12). Figs. 5-9. External views and complete serial dissections of a specimen from Falkland Plateau Sample 71-511-24-5,69-71 showing a broad portical flap (316 /xm) . Figs. 11-13. External views and complete dissection Maud Rise specimen from Sample 113-690C-19X-3,119-123 (230 /xm) . Figs. 14-17. Complete dissections of several specimens from the Maud Rise (Sample 113-690C-20X-3,116-118) showing consistent similarity in their Initial whorl morphologies. 14: 262 /xm. 15: 253 /xm. 16: Width of photo — 141 /xm, 17: 310 /xm. Figs. 18-19. External view and complete serial dissection of Falkland Plateau specimen from Sample 71-511-24-5,69-71 (362 /xm) . . . 120

Plate X. Santonian specimens of Archaeoglobigerina bosauensis Pessagno from Falkland Plateau Sample 71-511-42-5,27-29. Figs. 1-5. Exterior views, micrograph, and serial dissection of a kummerform adult specimen (355 /xm). Figs. 6-7. Exterior view and complete dissection of a juvenile specimen (273 /xm) . Fig. 8. Complete dissection of an adult specimen (288 /xm) . Fig. 9. Enlarged view of an adult specimen showing the initial whorl morphology (width of photo - 75 /xm) . Figs, 10- 15. External view and serial dissections of an adult specimen. Note the globigerine morphology of the penultimate whorl showing an umbilical-extra-umbilical aperture and more axially compressed, hedbergellid morphology of the initial whorl showing an extra-umbilical aperture and smooth outer chamber walls (325 /xm) . Fig. 16. Complete dissection of an adult specimen (292 /xm)...... 122

Plate XI. Figs. 1-8. External and micrograph views and serial dissections of a single specimen of Globotruncana cretacea (d'Orbigny) from Campanian Sample 71-511-34-4,1-3. Note the reniform chamber morphology that appears in the initial whorl and continues throughout the ontogeny (424 /xm) . Figs. 9-16. Specimens of Archaeoglobigerina mateola n. sp. from upper Maastrichtian Sample 113-690C-18X-2,119-123. 9-12: External views of specimen with an aberrant final chamber and view showing dissected ultimate whorl. Note the smooth surface of the penultimate whorl chambers (280 /xm) . 13, 16: Serial dissection of a strongly spinose specimen revealing penultimate whorl chamber and initial whorl mophology (306 /xm). 14: Complete dissection of a specimen with a large (28 /xm) prolocular chamber. 15: Complete dissection showing initial whorl morphology (278 /xm)...... 124

xxv i Plate XII. 1. Guembelitria cretacea Cushman, Sample 119-690C-20X- 3,116-118. 2. Heterohelix glabrans (Cushman), Sample 119- 690C-19X-1,119-123. 3. Heterohelix globulosa (Ehrenberg), Sample 119-690C-17X-3,119-123. 4. Heterohelix pulchra (Brotzen), Sample 119-690C-19X-1,119-123. 5-6. Heterohellx pulchra (Brotzen), Sample 119-690C-20X-3,116-118. 7. Gublerlna compressa (van der Sluis), Sample 119-690C-18X- 4,95-99. Globigerinelloic ;s alvarezl (Eternod Olvera), Sample 119-689B-30X-3,78-83. Globigerinelloldes Impensus Sliter, Sample 119-690C-22X-4,118-122. 11-12. Globigerinelloldes multisplnatus (Lalicker), Sample 119-690C- 20X-5,108-110. 14-15. Globigerinelloldes subcarlnatus (Bronnimann), Sample 119-690C-17X-3,119-123. Scale bar for Fig. 1 Is 25 microns and for Figs. 2-16 is 50 microns. . . . 179

Plate XIII. 1. Schackoina multlspinata (Cushman and Wickenden), Sample 119-690C-20X-5, 108-110. 2-4. Hedbergella holmdelensls Olsson, Sample 119-690C-21X-4, 118-122, 5, 9- 10. Hedbereella sliteri n. sp., holotype, Sample 119-690C- 18X-5,46-49. 6-8. Hedbergella monmouthensis (Olsson), Sample 119-690C-20X-5, 108-110. 11-12. Archaeoglobigerina australis n. sp., neanic specimen, Sample 119-690C-19X,CC. 13. Archaeoglobigerina australis n. sp., Sample 119-690C-20X-3. View of with final adult whorl removed, showing similarity of penultimate whorl chambers to neanic specimen of Figs. 11-12. Scale bar for Figs. 1 -13 is 50 microns...... 181

Plate XIV. 1. Archaeoglobigerina australis n. sp., s.s., Sample 119-690C-19X-3,119-123. Note the considerable varlablity of chamber development, umbilical size, and apertural flaps. 2-4. Archaeoglobigerina australis n. sp., holotype, Sample 119-690C- 19X-3, 119-123. 5. Archaeoglobigerina australis n. sp., s .1., Sample 119-690C-19X-3,119-123. 6. Archaeoglobigerina australis n. sp., s .1., Sample 119-689B-30X-3,83-87. 7. Archaeoglobigerina australis n. sp., s.l., Sample 119-689B-28X-3,83-87. 8-10. Archaeoglobigerina mateola n. sp., holotype, Sample 119-690C-20X- 3.119-123. Scale bar for Figs. 1-10 is 50 microns...... 183

Plate XV. 1. Archaeoglobigerina mateola n. sp., Sample 119-690C- 20X-3,119-123. 2. Archaeoglobigerina mateola n. sp., Sample 119-689B-28X-1,76-80. 3. Archaeoglobigerina mateola n. sp,, Sample 119-690C-18X-2,99-103. Enlarged cross-sectional view of the outer wall showing microstructure of distinctive large spines that characterize this species. 4. Ru g o t rune ana clrcumnodifer (Finlay), Sample 119-690C-17X-3,119-123. 5-7. Rugotruneana circumnodifer (Finlay), Sample 119-690C-19X- 3.119-123. 8-9. Rugotruneana clrcumnodifer (Finlay), Sample 119-690C-18X-5,46-49. Note the absence of a visible keel, but presence of an imperforate peripheral band. 10. Rugotruncana clrcumnodifer (Finlay), Sample 119-690C-17X-3,119-123. 11. Globotruncanella petaloidea (Gandolfi), Sample 119-690C-18X-

xxvii 1,119-123. Scale bar for Figs. 1-2, 4-11 is 50 microns and for Fig. 3 is 10 microns...... 185

Plate XVI. 1-2. Globotruncanella havanensis (Voorwijk), Sample 119-689B-28X-3,83-87. 3-4. Abathomphalus tnavaroensis (Bolli), Sample 119-690C-17X-3,119-123. 5-6. Abathomnhalus intermedlus (Bolli), Sample 119-690C-18X-5,46-49. 7-8, 12. Globotruncana subcircumnodifer (Gandolfi), Sample 119-690C- 18X.CC. 9-11. Globotruncana area (Cushman), Sample 119-690C- 18X-5,46-49. Scale bar for Figs. 1-12 is 50 microns. . , . 187

Plate XVII. Microradiographs of holotypes and several other species described in this study. 1. Hedbergella holmdelensis Olsson, Sample 119-690C-21X-4, 118-122. 2. Hedbergella monmouthesis (Olsson), Sample 119-690C-20X-5, 108-110. 3. Rugotruneana circumnodifer (Finlay), Sample 119-690C-18X- 5,46-49. 4. Hedbergella sliteri n. sp., holotype. Sample U9-690C-18X-5,46-49. 5. Hedbergella sliteri n. sp., from Falkland Plateau DSDP Site 327, Sample 71-327-10-3,22-24. Note the differences in ontogenetic morphology between the microradiographs of H. sliteri and those of H. holmdelensis and g. monmouthensis. 6. Archaeoglob jgerlna mateola n. sp., holotype, Sample 119-690C-20X-3,119-123. 7. Archaeoglobigerina australis n. sp., holotype, Sample 119- 690C-19X-3,119-123. 8. Archaeoglobigerina australis n. sp. Juvenile form from DSDP Site 511, Sample 71-511-23-4,67-69. 9. Archaeoglobigerina australis n. sp., Sample 113-690-19- 6,119-121. Edge view showing ontogenetic changes in morphology...... 189

Plate XVIII. Fig. 1. Globigerinelloides impensus Sliter, Sample 114-700B-43R-3,140-144. Figs. 2-3. Hedbergella monmouthens is (Olsson), Sample 114-698A-16R-2,67-71. Figs. 4, 8. Hedbergella sliteri n. sp., Sample 114-698A-16R-2,67-71. Figs. 5-6. Hedbergella sp., Sample 114-700B-47R-4,25-29. Fig. 7. Hedbergella sp., Sample 114-700B-46R-1,124-128. Figs. 9-10. Archaeoglobigerina australis n. sp., Sample 114- 698A-17R-1,28-32. Figs. 11-12. Archaeoglobigerina australis n. sp., Sample 114-698A-17R-2,12-16. Scale bar for all figures is 50 microns...... 231

Plate XIX. Fig. 1. Archaeoglobigerina australis n. sp., Sample 114-698A-17R-1,28-32. Fig. 2. Archaeoglobigerina mateola n. sp., Sample 114-698R-16R-1,67-71. Fig. 3. Archaeoglobigerina mateola n. sp., Sample 114-16R-1,67-71. Figs. 4-5. Rugotruneana circumnodifer (Finlay), Sample 114-698A-17R- 1,12-16. Figs. 6-7. Rugotruncana circumnodifer (Finlay), Sample 114-698A-16R-1,67-71. Figs. 8-9. Rugotruncana circumnodifer (Finlay), Sample 114-698A-16R-1,67-71. Fig. 10. Closeup view of imperforate peripheral band and beaded keel of same specimen shown in Figs. 8-9. Scale bars for Figs. 1-9 is 50 microns and for Fig. 10 is 10 microns. . . . 233

xxvi i i Plate XX. Figs. 1-2. Globotruncana area (Cushman), Sample 114- 698A-16R-1,67-71. Figs. 3, 6-7. Globotruncana linnetana (d'Orbigny), Sample 114-700B-47R-5,12-16. Figs. 4-5. Globotruncana linneiana (d'Orbigny), Sample 114-700B-47R- 4,25-29. Fig. 8. Globotruncanella havanensis (Voorwijk), Sample 114-698A-17R-2,12-16. Fig. 9. Globotruncanella petaloidea (Gandolfi), Sample 114-700B-39R-4,72-76. Fig. 10. Abathomphalus mavaroensis (Bolli), Sample 114-698A-16R-1,67- 71. Scale bars for Figs. 1-10 is 50 microns...... 235

xxix LIST OF APPENDICES

APPENDIX PAGE

Appendix A. Counts of foraminifers from the >150 micron size fraction for all samples studied, Site 689...... 315 Appendix B. Counts of foraminifers from the <150 micron size fraction for all samples studied, Site 689...... 317 Appendix C. Counts of foraminfers from the >150 micron size fraction for all samples studied, Site 690...... 319 Appendix D. Counts of foraminifers from the <150 micron size fraction for all samples studied, Site 690...... 321 Appendix E. Southern Hemisphere planktonic foraminifers reported for the Campanlan-Maastrichtian of the Late Cretaceous. Paleolatitudes for each reported occurrence are shown in parentheses and are listed with references on Table 8. . . . 323

XXX CHAPTER I

INTRODUCTION

One of the greatest challenges in paleoceanographic and

paleoclimatic research has been understanding the nature of oceanic

and atmospheric circulation patterns during non-glacial times. The

absence of polar ice implies a warm global climate with considerably

reduced latitudinal thermal gradients, resulting in substantially

different modes of heat transport. Modeling such a global climatic

state for the geologic past cannot rely on many uniformitarian

assumptions, or disagreement between the modeled and "observed"

paleoclimate will result (Gates, 1982).

Testing of paleoclimatic models requires a global distribution of quantitative and qualitative paleotemperature data extending from polar to equatorial regions and from shallow to deep ocean settings.

Quantitative data are derived primarily from measurement of oxygen

isotopic ratios preserved in the calcareous shells of fossil marine organisms. This approach becomes less reliable with increasing geologic age because of more pervasive influence of diagenetic alteration on the shell chemistry. Qualitative information can be obtained from a variety of observational studies, including analysis of global sediment distribution patterns, plant physiogonomy studies, and distributional analysis of marine and nonmarine organisms.

1 Interpretations of paleoclimatic conditions throughout geologic

time depend on several important criteria. First, there must be an accurate geochronologic framework by which geological events can be correlated. This is particularly a problem in remote regions or in restricted sedimentary facies that lack stratigraphically important fossil species or a reliable source of radiometric age control.

Second, sedimentologic and paleontologic tools used to infer paleoclimatic conditions must be very carefully scrutinized. Our understanding of factors controlling patterns of sediment and biotic distributions in the modern world is sufficiently limited to warrant extreme caution in interpreting those of the geologic past. Greater uncertainties arise with materials of increasing geologic age and burial depth, because of the higher likelihood for diagenetic alteration. Finally, an abundance of closely spaced and synchronous data spread over a broad geographic area must be obtained for accurate reconstruction of the paleoenvironmental history of a region.

Paleoclimatic data recovered from the polar regions are highly desirable because they permit determination of the minimum extremes of global temperature. However, this information is largely unavailable from Antarctica because 98% of the continent is covered by a thick ice sheet. Until samples of pre-glacial sediments are recovered from beneath the present Antarctic ice-sheet, the only means of interpreting Antarctic paleogeography and paleoceanography for the

Cretaceous is by biogeographic and geochemical analysis of fossils deposited in surrounding high paleolatitude localities. 3

6 0 0 30 0 30

60 60

Antarctic watar 3*7*611 090^688

JRI

90 90

130

ISO 180 150

Foraminifers have proven to be particularly valuable in

paleoceanographic studies because of their 1) distinctive patterns of

distribution with latitude, depth, and local depositional environment,

2) sensitivity to changes in oceanographic conditions, and 3) utility

in biostratigraphy and paleotemperature analysis. Although some

interpretations may depend on uniformitarian assumptions of

foraminifer life strategies, the overall patterns of distribution,

combined with analyses of oxygen and carbon isotopic compositions

preserved in the foraminifer shells, provide valuable information on

past vertical and meridional marine temperature gradients and patterns

of surface and bottom water circulation.

New information on high latitude foraminifer distributions was

recently obtained from the Antarctic and subantarctic regions during

Ocean Drilling Program (ODP) Legs 113 and 114 to the Weddell Sea and

southern South Atlantic Ocean and ODP Legs 119 and 120 to the southern

Indian Ocean. One of the major objectives of each of those cruises was to reconstruct the paleoceanographic and paleoclimatic history of

the high southern latitudes from analysis of upper Mesozoic through upper Cenozoic sediments. Ocean Drilling Program (ODP) Sites 689,

690, 698, 700, 738, and 750, which were drilled near or poleward of

the Antarctic Convergence (Fig. 1), all recovered Upper Cretaceous and

Cenozoic sediments yielding abundant and generally well-preserved

foraminifers and other microfossil groups. This dissertation focuses on analysis of upper Campanian-Maastrichtian foraminifers from the southern South Atlantic sites and their comparison with coeval foraminifers at lower latitude regions. Results from this study 5 should provide a basis for paleoclimatic and paleoceanographic

interpretations. Before any broad inferences can be made, however, several factors unique to the study of Cretaceous foraminifers from the high southern latitudes need to be addressed. These are outlined below.

PROBLEMS WITH HIGH SOUTHERN LATITUDE BIOSTRATIGRAPHY

Correlation of high southern latitude foraminifer assemblages with lower latitude assemblages has been difficult. Differences in faunal character between the low and high latitude sites are probably related to the effects of environmental instability and the physical extremes prevalent in high latitude regions, such as greater seasonality and lower marine temperatures. Factors that have inhibited accurate sediment dating and correlation within the Cretaceous circum-Antarctic region include the following:

1) Morphologic convergence and variability of planktonic foraminifers. Previous attempts to apply low latitude species concepts of Upper Cretaceous planktonic foraminifers to high latitude globigerine morphotypes have resulted in considerable taxonomic confusion and inconsistent age determinations. Difficulties arise among the high latitude forms because of their considerable range of morphologic variability and conflicting presence or absence of taxonomic characters that are important for determining their classification.

2) Low species diversity and longer species duration of high latitude assemblages. The most widely used biostratigraphic schemes 6 for the Upper Cretaceous depend on the presence of stenothermal planktonic foraminifer taxa, which rarely occur in polar and subpolar regions. Instead, high latitude planktonic faunas are dominated by eurythermal globigerine species that usually have little biostratigraphic value. Because of the relatively slow evolutionary turnover, datum events are more widely separated in geologic time and, therefore, biostratigraphic resolution in high latitude regions is generally quite poor.

The recent recovery of relatively complete and fossiliferous upper

Campanian-Maastrichtian deep sea sections from several areas of the high southern latitudes enables development of a more precise geochronologic framework for this area than was hitherto possible.

High southern latitude planktonic foraminifer and calcareous nannoplankton first and last occurrences are correlated for the first time with a good magnetic polarity reversal record preserved at two of the southern South Atlantic sites,

3) Poorly defined Upper Cretaceous stratotypes in the Southern

Hemisphere. The most complete Upper Cretaceous shelfal marine sequences within the circum-Antarctic occur in the James Ross Island region of the Antarctic Peninsula, New Zealand, and southern South

America (Figs. 2, 3). Foraminifer zonations and chronostratigraphic subdivisions proposed for these regions (see Chapter V, Fig. 44) have limited extra-basinal utility for several reasons. First, foraminifer faunas from southern Chile have been inadequately illustrated and include frequent usage of open taxonomic nomenclature and invalid species names, such that age assignments of the local stages may be 7

J « m « l H 6 « i 54*00'W T Jrv Cta^aain peninsula] i

ANTARCTICA WEDDELL SEA

S T O N S ttT VEGA ISLANO

LAGRtLIUS

K0T1CK • H U M P S / 64*00'S- POINT ISLAND/

ULA POINT

COCKBURN ISLAND

LOWER TERTIARY ISLAND SEDIMENTS i i r s SOBRAL FM. SEYMOUR .□ L 0 P E 2 DE BERTOOANO ISLAND U GUSTAV GROUP SN O W HILL 0 5 10 15 20 25 ISLAND

KILOMETERS 58*00'W 57*00'W 1

.74

30 *

Figure 3. Late Cretaceous paleogeographic reconstruction showing the high southern latitude distribution of the distinctive benthic foraminifer species Frondlcularia rakauroana (Finlay). Arrows show possible communication routes for this species. la - Marlborough, New Zealand; lb - Southern Hawkes Bay, New Zealand; lc - Northland, New Zealand; 2 - Lord Howe Rise, DSDP Leg 21, Site 208; 3 - Seymour Island; 4 - Minilya Well no. 1, Carnarvon Basin, Australia, Reconstruction after Smith et al, (1981) for 80 Ma, (From Huber and Webb, 1986.) 9

inaccurate (see Charrier and Lahsen, 1969; Natland and others, 1974).

Second, detailed stratigraphic information is lacking from many of the southern South American Upper Cretaceous outcrops. Third,

UpperCretaceous foraminifer assemblages of the Trochammina globigeriniformis and Rzehakina eoieona Zones in New Zealand (Webb,

1971) and in the Magallanes (Austral) Basin of southern South America

(Halumian and Masiuk, 1976) are predominantly facies-controlled.

Finally, the stratotypes used for definition of the Piripauan and

Haumurian Stages (Upper Cretaceous) in New Zealand have been rendered inadequate, because of confusion between biostratigraphic and chronostratigraphic concepts and stage boundary definitions (Warren and Speden, 1977).

The Marambio Group on Seymour Island (Fig. 2) is better exposed and yields more complete stratigraphic information than any of the other circum-Antarctic shelfal marine sequences (see Huber, 1988).

However, the paucity of cosmopolitan indicator species from that sequence has precluded accurate age determinations.

4) Poor biostratigraphic definition of Upper Cretaceous stratotypes in Europe. The difficulty of constraining the limits of the Campanian and Maastrichtian stages in the high latitude regions, where there is a shortage of reliable indicator species, is further compounded by problems with definition of the European stratotypes.

The major hiatus separating the Campanian and Maastrichtian type sections (Jeletzky, 1951; van der Heide, 1954; Berggren, 1962; Surlyk,

1984) and disagreement on which fossil group best defines this 10

boundary level (Birkelund and others, 1984; Harland and others, 1982)

render the type boundary definition ambiguous.

There is presently no planktonic foraminifer datum event

recognized in the high southern latitudes that can be used to delimit

the latest Campanian from the earliest Maastrichtian. Instead,

recognition of this boundary depends on the occurrence of several

calcareous nannoplankton marker species (see Wind and Wise, 1983;

Pospichal and Wise, in prep.) and reliable correlation with the magnetic reversal stratigraphy.

5) High latitude faunal diachroneltv. Temporal changes in

latitudinal temperature gradients have been inferred to strongly affect biostratigraphic resolution in high latitude regions because of

the resultant migration of stenothermal taxa. There is considerable uncertainty as to whether the stratigraphic distribution of high latitude species represents their whole evolutionary range or a partial range resulting from intermittent migrations. For example, the distribution of the calcareous nannoplankton species Nephrolithus freciuens GorkA, which is traditionally used as a late Maastrichtian index fossil in Tethyan zonal schemes, is time transgressive from the high to low latitudes, with its oldest extra-tropical occurrence reported as late middle Maastrichtian at DSDP Site 249 (Wind, 1979).

The distribution of Nephrolithus freauens and N. corvstus Wind on

Seymour Island, and their known stratigraphic ranges, were used as the primary means of dating the Cretaceous portion of the Seymour Island sequence (Huber and others, 1983), but there remains uncertainty as to exactly when and where these species evolved. 11

The first occurrences of several foraminifer taxa from the James

Ross Island region (Huber, 1988) and the deep sea southern South

Atlantic Leg 113 sites (Chapters III, IV) significantly predate or postdate their earliest known occurrences in lower latitude regions.

Causes for these diachronous distributions may include changes in continental configurations, variations in eustatic sea level, or fluctuations in the high latitude paleoclimate. Geological data and biostratigraphic control from the high southern latitude regions are presently insufficient to determine which of these factors had the greatest influence on the Late Cretaceous foraminifer distributions.

INFERENCES ON CRETACEOUS CLIMATE

The strong contrast between the climate of the Cretaceous period and that of the present Is well-documented for both the terrestrial and marine realms. Evidence for warm and equable conditions is derived primarily from the more globally uniform distribution of floras, faunas, and climatically sensitive sediments, as well as the absence of cold climate indicators (Frakes, 1979, 1986; Barron, 1983).

The terrestrial record shows that the Cretaceous and early Tertiary high latitude environment was very favorable for growth of deciduous and coniferous forests as well as large vertebrates. For example, diverse and abundant floras occur as far as 85°N paleolatitude in mid-

Cretaceous sediments of the Alaska North Slope (Spicer and Parrish,

1986) , and up to 756S paleolatltude in Lower and Upper Cretaceous sediments in Antarctic and circum-Antarctic sediments (Jefferson,

1982; Douglas and Williams, 1982; Francis, 1986). 12

30' COMPOSITE TEMPERATURE CURVE FOR LOW LATITUDES f / ‘ •* / • x 1 « o ^ \ /\ /\ r « / '

T k M £ L 1 £ L 1 M It L I.E.. IsfcwjEmlcpel AfUe* 1A * lfl ■» r [h*u« W b«rr I PL] MIOCENE ODGOCEHC EOCENE PALEO. CRETACEOUS u r-- 1--- 1-- 1 i I 0 2 0 40 60 6 0 100 120 14 AGE

Figure 4. Oxygen isotope paleotemperature curve (slightly modified from Douglas and Woodruff, 1981) based on analyses of planktonic and benthic foraminifers and calcareous nannoplankton from equatorial Pacific Deep Sea Drilling Project sites. Upper curve represents surface water paleotemperature estimates and bottom curve represents estimates for bottom water paleoteraperatures. Note the decline in surface and bottom water temperatures shown from the early Campanian through the Maastrichtian (arrows). Plots compiled from Douglas and Savin (1973, 1975), Savin et al. (1975), and unpublished data (Douglas and Woodruff, 1981). 13

OXYGEN ISOTOPE PALEOTEMPERATURES

Quantitative estimates of Cretaceous polar temperatures are meager

in comparison with the Cenozoic paleotemperature data base. Oxygen

isotope analyses of Late Cretaceous belemnite guards from New Zealand,

deposited at about 60°S (Smith et al., 1981), indicate surface water paleotemperatures of 13.5° to 16°C (Stevens and Clayton, 1971).

However, these values are not very reliable because of diagenetic alteration of the primary isotopic ratios (Frakes, 1986).

More trustworthy results have been obtained from oxygen isotope analyses of Upper Cretaceous deep-sea benthic and planktonic foraminifers. A frequently cited paleotemperature curve from Douglas and Woodruff (1981), reproduced as Fig. 4, shows upper Campanian-

Maastrichtian bottom water temperature estimates of 8° to 12°C and surface water estimates between 18° and 27°C. This curve also shows a gradual decline in paleotemperature values from the middle Cretaceous through the latest Maastrichtian. Data for the Cretaceous part of the curve were derived from oxygen isotope analyses of benthic and planktonic foraminifers and coccoliths from the equatorial western

Pacific region (Douglas and Savin, 1973, 1975; Savin et al., 1975; unpublished data). There is some uncertainty whether this curve accurately reflects Cretaceous paleotemperatures, however, as foraminifers from the samples used show evidence of diagenetic alteration (E. Barrera, pers. conun., 1988). Assuming that the relatively warm temperatures estimated from the low latitude benthic foraminifers reflect warmth in the polar regions depends on a 14

DELTA 180 OF SELECTED SPECIES

o <0 0.6 - < ui 0.4 - 0.2

- 0.2 -

- 0.4 -

- 0.6 -

-0.B

0.3 0.5 0.7 0.9 1.3 ______Meters (Thousands) ______U. Camp./L. Moor / M. Maai. / tX Moos. j Doniort

Figure 5. Oxygen isotopic ratios of five benthic foraminifer species plotted against stratigraphic position and geologic age inferred for the nearshore Cretaceous section on Seymour Island. Evidence for preservation of the primary isotopic signal is shown by the quasi-sympathetic fluctuations of the delta 180 values for each benthic species. Note that a slight trend toward more negative (warmer) values from the middle to late Maastrichtian part of the sequence is indicated, but this is based on relatively few data points. Isotopic ratios of the species are indicated by the following symbols: squares, Cibicides sevmouriensis: pluses, Anamallnoides piripaua: diamonds, Lentlcullna macrodisca: triangles, Dentalina basiolanata: and crosses, Hoeglundina supracretacea. (From Barrera et al. , 1987) . Figure 6. Estimated range of temperatures (indicated by shaded area) of bottom shelf water and surface water at Seymour Island for each of the following intervals: a) late Campanian to early Maastrichtian, b) early to middle Maastrichtian, c) late Maastrichtian, and d) earliest Paleocene. Isotopic curves for each of the taxa are indicated as follows: squares, Cibicldes sevmouriensis: pluses, Anomalinoldes piilpaua: diamonds, Lenticulina macrodisca: triangles, Dentallna basiplanata: crosses, Hoegludina suoracretacea: inverted triangles, Globigerinelloldes multispinatus (planktonic species). From Barrera et al. (1987).

15 LATE CAMPANIAN EARLY-MIDDLE MAASTRICHTIAN 1 0 5 0 o 5 mo a a a 1.5 i c * Wale □•Ua 100 {SUOW) 2 5

- J - 3 3 5 7 9 1 1 5 7 » 1 1 Tamparolura (dtf C) Ttrnp^reiurw (4*$ C)

LATE MAASTRICHTIAN PALLOCENE 1

2,5

-i 7 9 3 7 9 i 1 fflmptrotur* (dag C) Tamparoi:ora (dag C)

Figure 6. 17 uniformitarian view of pre-glacial thermohaline circulation, which may be invalid if there was a major source of dense, saline water from shallow epeiric seas during the Cretaceous, as envisaged by Brass et al. (1982).

Few other oxygen isotope paleotemperature estimates for foraminifers from other ocean basins have been published. Mid latitude surface water estimates of 15° to 19°C for the late

Maastrichtian were determined by Boersma (1984) based on analyses of planktonic foraminifers from several South Atlantic DSDP sites.

Benthic foraminifer oxygen isotope ratios from the South Atlantic

Ocean are difficult to interpret because of the complex tectonic history of the different basins that comprised the Late Cretaceous

South Atlantic (Norton and Sclater, 1979), and because of diagenetic alteration of the isotopic signal of many of the samples.

Furthermore, some benthic paleotemperature estimates (e.g., Boersma,

1984) were derived from analyses of mixed benthic foraminifer assemblages rather than analyses of single species. Estimates of benthic paleotemperatures for late Maastrichtian waters at DSDP Site

527 on the Walvis Ridge range from 6.5° to 10°C (Shackleton et al. ,

1984), whereas benthic temperatures as high as 10° to 14°C were determined for DSDP Sites 355 and 357 in the Brazil Basin (E. Barrera and S. Savin, unpub. data, 1986).

Results of an oxygen isotope paleotemperature study of upper

Campanian through lower Paleocene foraminifers from Seymour Island, published by Barrera et al. (1987), are presented in Figs. 5 and 6. 18

The isotopic composition of Seymour Island samples deemed to be well preserved was the basis of the conclusion that Campanian through

Paleocene shelf waters near Antarctica ranged between 4.5° and 10.5°C.

Analysis of a single lower Maastrichtian planktonic foraminifer sample indicated surface water paleotemperatures ranging between 9° and 10.5°

C (Fig. 6). Similarity of the upper Campanian-Maastrichtian Seymour

Island paleotemperatures with the published isotopic ratios of benthic foraminifers from the equatorial western Pacific (Fig. 4), is compatible with the suggestion of Saltzman and Barron (1982) that deep water in most of the Late Cretaceous to early Tertiary oceans formed in high latitude regions. Much additional Late Cretaceous oxygen isotopic data is needed to test this hypothesis, however.

CRETACEOUS PLANKTONIC FORAMINIFER DISTRIBUTIONS

Previous studies of Upper Cretaceous planktonic foraminifer paleobiogeography in North America (Douglas, 1969) and along the eastern margin of the Pacific Ocean (Sliter, 1972) recognized meridional gradients in the total number of planktonic foraminifer species and in the diversity and relative abundance of species bearing single or double keels along the equatorial periphery of their tests.

Highest diversity in total number and number of keeled species was recognized among Tethyan assemblages, whereas higher latitude Boreal assemblages were characterized by their low diversity and lack of keeled species. These changes in taxonomic composition were inferred to reflect transition from warmer to cooler climatic belts because of their correlation with increasing latitude. Figure 7. Curve from Krasheninnikov and Basov (1986) showing relative climatic fluctuations at the Falkland Plateau during the Cretaceous through Cenozoic in the southern South Atlantic, as inferred from planktonic foraminifer distributional data. The curves drawn for the Late Cretaceous were based on the number of keeled planktonic foraminifers present and total species diversity of assemblages from Deep Sea Drilling Project Sites 327 and 511. Suggestion that globotruncanid (keeled) species are absent from the South Atlantic high latitudes was made prior to recovery of upper Maastrichtian sections yielding diverse keeled assemblages. No upper Maastrichtian sediments have yet been recovered from the Falkland Plateau, where this study was based.

19 r e l a t i v e temperature OSCILATIOVS IN PUEONTOLOGICU. e v e n t s

c o l d cold

P r e d o m i n i n e * o f s i l i c e o u t nvi c r o o r ^ i n \ t m a

20 -

lag** of c a ‘c*r# Oul and liliceout eiicroorga- n i a m a

Predominance of calcareous mi c roorgar* I a m i : rare ail ice* o u t f o t i i )i

60 - Absence of calcereut micro- p l a n k t o n

Aaeatrichtian 0 iaappearance of Globa

H a * i of apeciea diveraitf; p r t s r o f t e r a o p h H i t GIobotruncana

Predominance of Hedbergella C o n i a c i a n Globtgerinellotdaa, Arcbaeo 1 glob fgerina T g r o n i a n

100- Predo^inance of Hedbergella GlobigerineMoidea A I b ia n

Pare Hadbcrgella, Globigeri- n e I l o i d e a

Figure 7. 21

Krasheninnikov and Basov (1983, 1986) used changes in planktonic

foraminifer species diversity and presence or absence of keeled

morphotypes at several Falkland Plateau Deep Sea Drilling Project

(DSDP) sites (Fig. 7) to construct a curve of relative climatic

fluctuations. These authors noted an increase in the number of

thermophilic keeled species and maximum total diversity during the

early to middle Campanian, and they equated this with penetration of

warm, subtropical waters into the high latitude regions. A late

Campanian through Maastrichtian cooling was postulated by

Krasheninnikov and Basov (Fig. 7) based on the predominance of

impoverished planktonic foraminifer assemblages and absence of keeled

species at the Falkland Plateau deep sea sites.

Analyses of planktonic foraminifer distributions at ODP Sites 689,

690, 698 and 700 (Fig. 1) show that a significant influx of keeled

species and the highest species diversity both occur throughout the

southern South Atlantic region during the late Maastrichtian (see

Chapters III, IV). This was not recognized by Krasheninnikov and

Basov (1986) since no upper Maastrichtian sediments were recovered

from the Falkland Plateau. Nevertheless, these diversity trends

should reflect a climatic warming episode, if the same assumptions of

climatic control on planktonic foraminifer distributions are applied.

Lack of correlation with other quantitative and qualitative paleoclimatic evidence for this time period (Chapters III, IV, V)

suggests that more complex factors were controlling the distribution

of Upper Cretaceous planktonic foraminifers than was previously assumed. 22

CRETACEOUS CLIMATE MODELS

The problem of maintaining ice-free conditions in polar regions has been investigated using climatic simulation models (Barron et al.,

1981a; Barron and Washington, 1982, 1984; Barron, 1983) and the postulated land-sea distributions of Barron et al. (1981b) for 100 million years ago. Their results indicate that the inferred

Cretaceous geography could not account for the warm temperatures in polar regions. An increase in atmospheric C02 was suggested by Berner et al. (1983) and Barron and Washington (1984) to be the additional forcing factor to explain the paleoclimatic data. Strong correlations between changes in the atmospheric COa and climate variations have been documented for the Quaternary (Shackleton et al., 1983; Barnola et al. , 1987). Still, the causal link between global climate change and variations in concentrations of C0Z during the Cretaceous has not been unequivocally verified.

At present we can only speculate on the extent to which the polar regions were covered by oceans, marine seaways, or ice and how this

Influenced global Cretaceous climate. Climate sensitivity models have demonstrated the importance of polar land area in regulating global- scale temperature (Barron et al., 1984; Barron and Washington, 1984).

However, the presence of permanent ice cover in both polar regions inhibits direct sampling of sediments in the underlying basins, preventing an accurate portrayal of Arctic and, more significantly,

Antarctic land-sea distributions during pre-glacial times. Inaccurate portrayal of Antarctic paleogeography in the climate model simulations may partly explain the underestimated Cretaceous temperatures. For example, Barron et al. (1981b) and Barron (1987) depicted Antarctica as a wholly emergent continent occupying a polar position throughout the Cretaceous period. This is in conflict with the subglacial topographic profile map of Drewry (1983), which indicates the presence of extensive marine basins occupying much of

West Antarctica and parts of East Antarctica (Chapter V, Fig. 38).

Evidence for existence of intra-Antarctic seaways during the

Cretaceous has been suggested by several authors (e.g., Webb, 1979;

Zlnsmelster, 1982; Huber and Webb, 1986) to explain the dispersal of numerous high southern latitude invertebrate taxa (e.g., see Fig. 3).

Such seaways would surely have influenced the global heat budget and the patterns of marine circulation between the major oceans of that time.

MAJOR OBJECTIVES

The major research objectives of this dissertation include the following;

1. Conduct a detailed investigation of the ontogenetic morpholo of several trochospiral planktonic foraminifers from high southern latitude, upper Campanian-Maastrichtian samples to establish their taxonomic identity. These results will be compared with the ontogenetic morphometric observations from topotype specimens of several Upper Cretaceous species, enabling a more accurate assessment of the supra-specific classification of the high latitude morphotypes 24

2. Formally name and describe new species endemic to the

southern, extra-tropical Austral Province and define their

blostratlgraphic and paleobiogeographic ranges.

3. Document important planktonic foraminifer datum events at ODP

Sites 689, 690, 698, and 700 and establish their synchroneity and

biostratigraphic utility based on correlation with the calcareous

nannoplankton biostratigraphy and the magnetic polarity reversal

stratigraphy established for this region.

4. Provide a biostratigraphic framework for correlation of upper

Campanian-Haastrichtian planktonic foraminifer assemblages from all high southern latitude sites,

5. Document stratigraphic changes in the keeled and total species diversity of Campanian-Haastrichtian planktonic foraminifers from the

south polar regions and determine the timing and possible causes of paleoenvironmental changes in high southern latitude surface waters.

6. Infer patterns of surface circulation for the high southern

latitudes during Campanian-Maastrichtlan times based on planktonic and benthic foraminifer paleobiogeographic distributions.

7. Infer Late Cretaceous land-sea distributions within the

Antarctic continent based on occurrences of recycled marine and non marine microfossils and the paleobiogeographic distribution of planktonic and shallow marine benthic foraminifers.

PLAN OF STUDY

Chapters II through V in this dissertation are organized as separate manuscripts submitted or intended for publication. As a 25 result, some repetition of background information could not be avoided. It should be noted that the French spelling for the

Maastrichtian stage is preferred for this dissertation, but the

English spelling (Maestrichtian) is used in Chapters II and III In accordance with Ocean Drilling Program guidelines. Research results for Chapters II through V are summarized in abstracts presented at the beginning of each chapter.

Chapter II provides the taxonomic basis for recognizing three new planktonic foraminifer species found at several high southern latitude sites. This chapter includes description of new techniques employed to obtain ontogenetic morphometric data from planktonic foraminifers, comparison of the different morphometric parameters used, and a critical assessment of the conventional versus ontogenetic morphometric approaches to classification of Upper Cretaceous planktonic foraminifers. A phylogenetic scheme is also proposed for the species analyzed in Chapter II based on results of the morphometric comparisons.

Formal descriptions of the three new high southern latitude planktonic foraminifer species are included in Chapter III (ODP Leg

113 results). Biostratigraphic distribution data for planktonic foraminifers from ODP Leg 113 samples at Sites 689 and 690 (Fig. 1) are discussed in Chapter III, and a new zonal scheme for the late

Campanian-Maastrichtian time period is proposed. Significant stratigraphic changes in Maastrichtian planktonic foraminifer species diversity are also discussed in this chapter. 26

Chapter IV documents the distribution of upper Campanian-

Maastrichtian planktonic foraminifers from ODP Leg 114 Sites 698 and

700 (Fig. 1). The zonal scheme proposed for the Leg 113 foraminifers is applied in this chapter and important planktonic foraminifer and calcareous nannoplankton datum events are correlated among the high latitude sites. Species diversity trends similar to those recorded at

Sites 689 and 690 are portrayed and their regional significance is discussed.

A synthesis of Campanian-Maastrichtian paleobiogeographic distributions of planktonic and benthic foraminifers from nearshore and deep sea high latitude sites is presented in Chapter V.

Meridional gradients in total and keeled planktonic foraminifer species diversity are portrayed for the early Campanian, late

Campanian, early Maastrichtian, and late Maastrichtian based on published distributional data and results from the Legs 113 and 114 studies. Paleogeographic reconstruction maps for these four time periods, with plots of planktonic foraminifer species diversity, are also presented. Antarctic land-sea distributions for the Late

Cretaceous are also proposed based on planktonic and benthic foraminifer distributions among high southern latitude sites.

A summary of major results of this study is presented in Chapter

VI, along with a discussion of the paleoclimatic and paleoceanographic implications. A model of surface water circulation in the high southern latitude regions is proposed within this final chapter. CHAPTER I I

ONTOGENETIC MORPHOMETRICS OF SOME UPPER CRETACEOUS

PLANKTONIC FORAMINIFERS FROM THE HIGH SOUTHERN LATITUDES

ABSTRACT

Morphometric analysis of ontogenetic changes in test morphology is employed to determine the taxonomic status of several trochospiral planktonic foraminifer species from high southern latitude Upper

Cretaceous sediments. Ontogenetic morphometric data obtained from specimens of Hedbereella sliteri n. sp., Archaeogloblgerlna australis n. sp. (both juvenile and adult populations), and Archaeogloblgerina mateola n. sp. are compared with analyses of topotype populations of

Costellagerina oilula (Belford) and Rugoglobigerina rugosa (Plummer) .

Southern South Atlantic specimens of Archaeoelob i ge rina bosouensis and

Globotruncana cretacea (d'Orbigny) are also analyzed for comparison.

Numerous morphometric parameters, measured from test exterior observations of whole tests, contact microradiograph images, and

Scanning Electron Microscope (SEM) micrograph images of serially dissected foraminifers, are used to characterize developmental changes in morphology of the planktonic foraminifer species. The most useful parameters for distinguishing taxonomic differences are discussed for each method. Results show that the ontogenetic morphometric approach to study of planktonic foraminifers can be effectively used to resolve

27 28 appear homeomorphic in exterior view, and to establish a more

"natural" classification. Morphometric characterization of early growth stages of planktonic foraminifers enables their taxonomic identification in unstable environments where they may dominate. In addition, comparative ontogeny of species shows great potential for reconstructing phylogenetic lineages, characterizing evolutionary rates of morphologic change, and inferring physico-chemical factors in the surface water habitat that may have influenced changes in planktonic foraminifer growth morphologies.

INTRODUCTION

A stable taxonomic framework is of paramount importance in all faunal analyses for biostratigraphic, paleoclimatic, and paleoceanographic reconstructions. Therefore, the first and most important stage in any paleontological study should be to accurately identify fossil species using as many morphologic criteria as preservation will allow. Identification depends, however, on an adequate knowledge of the species in question, including its range of morphologic variability in space and time, which is lacking for most fossil groups. Although limitations of the fossil record prevent complete attainment of this information, the continuing refinement of stratigraphic knowledge on a global scale affords a considerably improved basis for correlation and a more detailed knowledge of species distributions.

One of the greatest difficulties in taxonomic studies is establishing a morphological classification that is universally 29

establishing a morphological classification that is universally

applicable to fossil species occurring in a wide range of

environmental habitats. Ideally, the morphologic parameters chosen to

represent a specific or supraspecific concept do not vary with areal

or temporal distance from the location where the type specimens were

defined. But, as Rhodes (1956, p. 35) noted, "Even if it were possible to describe the sum total of the attributes of a population,

it would still be impossible to recognise an absolute degree of differentiation (whether qualitative or quantitative) as being of

specific status. The variability of characters and attributes studied

in different taxonomic groups further complicates this problem."

Several strategies for taxonomic classification that can contribute to a better understanding of inter- and intraspecific variability

include: 1) recognition of a greater number of morphological criteria by which taxa can be compared, 2) quantitative and qualitative analysis of the ontogenetic changes in morphology among geographically or stratigraphically separated species populations, and 3) detailed comparison with populations of topotype specimens. Once the range of morphocharacter variablity for a species population has been characterized, isolated specimens can be Identified with greater confidence without recourse to biometrical methods.

The shells of planktonic foraminifers are formed by the successive addition of chambers throughout their life history, from the earliest formed proloculus through the final stage of the life cycle, which terminates after gametogenesis. The earlier formed chambers are obscured by the final whorl chambers in trochospiral foraminifers, and 30

Kt Y TO CHtTACFQuS PLAN* HC TROChOWiRAL UENERA

} KC^tKtw'l

Figure 8. An example of the conventional approach to classification of Upper Cretaceous planktonic foraminifers based on external morphocharacters, From Caron (1985, Fig. 1). 31 therefore, the ontogenetic morphology of whole specimens cannot be characterized using standard methods of light microscope or scanning electron microscope (SEM) observation of the test exterior. As a result, conventional taxonomic schemes used for planktonic foraminifers (e.g., see Fig. 8) have overlooked important morphologic information preserved in the early growth stages.

Ontogenetic changes in planktonic foraminifer morphology have been observed among both fossil and modern populations by a number of authors (e.g., Rhumbler, 1911; Parker, 1962; Banner and Blow, 1967;

Olsson, 1972; Blow, 1979), but no detailed ontogenetic studies were pursued until recently. Huang (1981) was the first to employ a test dissection and SEM observation method to portray the ontogenetic morphology of several Recent and Neogene species. Sverdlove and B6

(1985) described a method for obtaining ontogenetic morphometric information from light microscopic analysis of transluscent specimens embedded in plastic. In a study of the planktonic foraminifer species

Globleerinoides sacculifer (Brady) and G. ruber (d'Orbigny) recovered from surface plankton tows offshore Barbados (Caribbean Sea), Brummer et al. (1987) illustrated five developmental growth stages, designated as the prolocular (-embryonic), juvenile, neanic, adult, and terminal

(—reproductive) stage. These were defined on the basis of significant quantitative and qualitative changes in test morphology (e.g., test size, chamber inflation, apertural position, etc.), as well as changes in vital behavior observed in laboratory cultures. All of the above authors convincingly demonstrated the importance of ontogenetic analyses in improving taxonomic classification schemes. They further 32

emphasized potential applications of ontogenetic information in

phylogenetic reconstructions, testing of evolutionary models, as well

as improving biostratigraphic resolution, particularly within paleoenvironmentally stressed habitats.

A need for extensive revision of taxonomic concepts for several high southern latitude planktonic foraminifer groups was recognized by

Huber (1988) in a study of upper Campanian-Haastrichtian assemblages from the James Ross Island region (northern Antarctic Peninsula).

Forms identical to species identified by Sliter (1977) as Hedbergella roonmouthensis (Olsson), Rugoglobieerina pilula Belford, and

Ruglobigerina rotundata Bronnimann from Falkland Plateau Deep Sea

Drilling Project (DSDP) Site 327 were found among the Antarctic assemblages. However, comparison with type specimens of these species showed considerable differences from the original type descriptions.

Moreover, species concepts varied significantly among the other

Cretaceous high southern latitude studies of Krasheninnikov and Basov

(1983) from DSDP Site 511 (Falkland Plateau) and Webb (1973b) from

DSDP Site 208 (Lord Howe Rise). Illustrations of the problematic species are reproduced in Plate 1. The taxonomic uncertainties were not resolved in the Huber (1988) Antarctic foraminifer study, as the problematic forms are morphologically diverse (PI. II, Figs. 1-12) and very low in abundance.

Analysis of planktonic foraminifers from Ocean Drilling Program

(ODP) Legs 113 (Chapter III) and 11^ (Chapter IV), in the southern

South Atlantic Ocean, revealed forms identical to the problematic species described from the Falkland Plateau and Antarctic Peninsula. PLATE I. Upper Campanian-Maastrichtian planktonic foraminifers from southern, extra-tropical latitudes previously illustrated in Deep Sea Drilling Project reports. The taxonomic classification of these forms is revised in this study. Figs. 1-2. Hedbergella sliterl n. sp. , previously identified as Hedbereella monmouthensis (Olsson) by Webb (1973b, PI. 3, Figs. 1-2) from south Tasman Sea DSDP Site 208. Figs. 3-5. Hedbergella sliterl n. sp., previously identified as Hedbergella holmdelensis Olsson by Sliter (1977, PI. 2, Figs. 1-4) from the Falkland Plateau DSDP Site 327. Figs. 6, 10-11. Archaeoglobigerlna australis n. sp. (juvenile form), previously identified as Hedbergella monmouthensis (Olsson) by Sliter (PI. 3, Figs. 1-3) from Falkland Plateau DSDP Site 327. Figs. 7-9. Archaeoelobigerina australis n. sp. (juvenile form), previously identified as Hedbergella monmouthens is (Olsson) by Krasheninnikov and Basov (1983, PI. 6, Figs. 5, 7-8) from Falkland Plateau DSDP Site 511. Figs. 12-14. Archaeoglobigerlna australis n. sp, (gerontic form), previously identified as Rugoglobigerina ollula Belford by Sliter (1977, PI. 10, Figs. 7-9) from Falkland Plateau DSDP Site 327. Figs. 15-17. Archaeoglobigerlna australis n. sp. (gerontic form), previously identified as Rugoglobigerina pilula by Krasheninnikov and Basov (1983, PI. I, Figs. 4-6) from Falkland Plateau DSDP Site 511. Figs. 18-20. Archaeoglobigerlna australis n. sp. (gerontic form), previously identified as Rugoglobigerina pustulata Bronnimann by Krasheninnikov and Basov (1983, PI. 10, Figs. 10-12) from Falkland Plateau DSDP Site 511. Figs. 21-22, 26-27. Archaeoglob1yerina australis n. sp. (gerontic form), previously identified as Rugoglobigerina rotundata Bronnimann by Krasheninnikov and Basov (1983, PI. I, Figs. 7-11) from Falkland Plateau DSDP Site 511. Figs. 23-25. Archaeoglobigerina australis n. sp. (gerontic form), previously identified as Rugoglobiperina rotundata Bronnimann by Sliter (1977, PI. I. Figs. 1- 3) from Falkland Plateau DSDP Site 327. Scale bars represent 50 microns.

33 34

Plate I

(

f A i ) ^ ' J f .!*. £ ■ ? t- ' ■ - -' ' V * ; ' % .-s' ■%.. - i.*

S 0 * * ,1 - ■- f

■ * . ,-3 lfc«L f

**\‘ ±*ry-fi* n PLATE II. Juvenile, kummerform adult, and normalform adult planktonic foraminifers from Seymour Island (northern Antarctic Peninsula) previously designated by Huber (1988, p. 207, Figs. 29.1- 14, 30.5-10) as Rugoglobigerina? sp. 1, but presently included in Archaeoglobigerlna australis n. sp. Microradiographs of each specimen (Figs. 2, 6, 10) show the chamber arrangement in the penultimate and earlier whorls. Figs. 1-4. Juvenile form from sample 165. Figs. 5-8. Kummerform adult form from sample 165. Figs. 9-12. Normalform adult form from sample 415,

35 Kummwform Adutt (0.213 mm) 37

Because these morphotypes dominate the high latitude deep sea assemblages and are distributed throughout the southern South Atlantic region, a detailed taxonomic study was necessaryconducted before further biostratigraphic or paleoceanographic determinations could be made. Image analysis of x-radiographs and SEM observations of serial test dissections (described below) were used to reveal ontogenetic changes in planktonic foraminifer morphology. These afforded an improved means of comparing morphologically diverse populations of high latitude species with topotype populations of species previously assigned to the high latitude morphotypes.

The primary objective of this study is to provide a more stable taxonomic framework upon which subsequent high latitude biostratigraphic, paleobiogeographic, and paleoceanographic interpretations can be based. Future work will incorporate the stratophenetic approach, which may reveal information on evolutionary change and phylogenetic relationships among Upper Cretaceous planktonic foraminifers, in addition to enabling more detailed paleoceanographic and paleoclimatic reconstructions.

MATERIALS

A total of 574 adult and 64 juvenile (pre-adult) specimens of seven different planktonic foraminifer species were studied from collections made by the author from the Antarctic Peninsula and ODP

Leg 113 samples, the DSDP core repository at Scripps Institute for

Oceanography, American Gulf Coast samples collected by P.N. Webb and stored at The Ohio State University, and several other researchers. 38

Samples used in this study are from: 1) lower to middle Maastrichtian

Cores 113-689B-28X, 30X, -690C-19X, and -20X from ODP Leg 113, drilled on the Maud Rise, southern South Atlantic (640-650S, 1-3°E, 2084 m to

2920 m water depth; see Chapter III); 2) lower Maastrichtian Sample

71-511-24-5, 69-71 cm, DSDP Site 511, drilled on the Falkland Plateau, southern South Atlantic (51°S, 47DE, 2,589 m depth; see Krasheninnikov and Basov, 1983); 3) lower to middle Maastrichtian Sample 36-327A-10-

3, 22-24 cm from DSDP Site 327, from the Falkland Plateau, southern

South Atlantic (52°S, 46°W, 2410 m depth; see Sliter, 1977); 4) samples

165 and 415 from the lower Maastrichtian of the Lopez de Bertodano

Formation on Seymour Island, Antarctic Peninsula (64°S, 57°W; see

Huber, 1988); 5) Maastrichtian Kemp Clay, Austin County, Texas, (New

Zealand Geological Survey sample F101166 and F101167); 6) middle

Maastrichtian Redbank Formation, Sample NJK-3 (provided by R.K.

Olsson, Rutgers University); and 7) Santonian Toolonga Calcilutite, sample #71640043, Pillawara Hill, Western Australia (topotypes of

Costellaeerlna pllula (Belford) provided by Dr. G. Chaproni6re, Bureau of Mineral Resources, Australia).

APPROACH TO STUDY

SAMPLE PREPARATION

Sediment samples were dissaggregated in water by gentle stirring over a warm hotplate for five to ten minutes, then ultrasonically cleaned for about two minutes, stirred again and wet-sieved through a

63 micron screen. The seived residues were ultrasonically cleaned again for a few seconds then dried and picked for foraminifers. 39

Kyjstsr • Apmtm t trnmt A. - Apwtum w tti

Figure 9. Morphometric parameters measured from external views of planktonic foraminifers. Apertural heighf.width ratios measured only on specimens showing extraumbilical apertures. 40

MCWPHOMETHKi PJtfUMETgna

Uw/Jw, - Panuttm

cyt, + ^ - rr chw i»f pnaoMon gS0> * flb * P oaU an et ginirjng ounct

Figure 10. Morphometric parameters measured from x-radiograph images. Initial whorl dimensions were only obtained on the most evolutely coiled specimens. 41

MORPHOMETRIC PARAMETERS

P » Proloculus diameter Iw « Initial whorl diam eter # 's « Initial whorl cham ber num ber

Figure 11. Morphometric parameters measured from the initial whorl exposed after complete test dissection. The initial whorl chamber number is determined from the sequential count of chambers following the proloculus (P) to the point of overlap with the proloculus-deuteroconch (- first chamber) suture, recorded as 0.25 chamber increments. 42

EXTERNAL MORPHOLOGY

Features on the exterior of planktonic foraminifer tests are the primary morphocharacters used for conventional taxonomic classification schemes and phylogenetic reconstructions. Therefore, all foraminifer groups in this study are Illustrated with SEM micrographs showing the standard umbilical, edge, and spiral views and enlarged views of important external structures. Measurements of apertural height/width ratios (A^A*) on specimens with extra-umbilical apertures and test breadth/diameter ratios (B/D) (Fig. 9; Table 1) were taken using a Wild*" microscope with a camera lucida attachment, a mouse driver and a digitizing tablet linked with an IBM1™ personal computer. A Bioquant*” biometrics program was used to calculate the digitized size parameters.

Measurement precision using external views of specimens under the light microscope is considerably less than with the methods described below, particulary for specimens smaller than 250 microns. Although variation about the mean for 20 scale bar measurements was + or - 8 microns at 50X magnification, greater uncertainty (up to + or - 15 microns) occurs with measurement of three-dimensional images with reflective surfaces, such as foraminifer shells.

CONTACT MICRORADIOGRAPHY

Methods

Foraminifer microradiographs were obtained by adapting the methods described by Arnold (1982). A 2 x 5 inch cardboard sheet with a grid of 30 holes was backed with tracing paper and used to hold the 43 foraminifer specimens during the x-ray exposure. The tracing paper was coated with gum tragacanth so that the mounted specimens could be oriented to obtain a full axial image. The Image was recorded on 2 x

5 inch sheets of High Resolution KODAK Film #SO-343, with the emulsion side placed in contact with the bottom of the cardboard sheets. The film and mounted specimens were placed on the middle shelf of a

Hewlitt-Packard Faxitron x-ray unit and exposed at 40 KVP for 40 minutes. Developed film was cut, labelled, mounted on glass slides, and photographed through a Leitz4® Orthoplan microscope. The best images were obtained from low trochospiral specimens free of adhering matrix and without infilled chambers.

Morphometric data were collected from the microradiographs by measuring the x-ray images on a video screen using a digitizing tablet linked to an IBM personal computer, a video camera mounted on a

Leitz4® Orthoplan microscope and Bioquant4® biometrics software.

Because vertical portions of the chamber walls are opaque to x-rays, the cross-sectional outline of the axial periphery, chamber sutures, and whorl sutures appear as unexposed curves on the microradiographs

(e.g., see Fig. 10). Individual distances, size ratios, and area measurements can be rapidly and accurately obtained from the microradiographs using the biometrics software and hardware.

Precision in measuring the x-ray images was determined to be within + or - 2 microns at 160X magnification.

Morphometric Parameters

Morphometric characters measured from the x-ray images are 44

portrayed in Fig. 10 and listed in Table 1. The number of chambers in

the ultimate whorl (U) were accurately calculated by adding the number

of whole chambers to the ratio of the distance between the exterior

sutural contacts of the first chamber in the ultimate whorl (cx) and

the total of c1+c2, the length of the first ultimate whorl chamber

overlapped by the final chamber. The same method was used to

determine the number of chambers in the penultimate whorl (P). The

presence of kummerform (reduced) final chambers was determined based

on the ratio of the ultimate chamber width (Uwj) and the penultimate

chamber width (Uw2) ; values of less than one were recorded as

kummerform. The ratios of the size of the pultimate (Uw2) and

antepenultimate (Uw3) chambers were also recorded using this method.

The position of the generating curve in relation to the coiling axis

(see Raup, 1966) was determined by measuring the ratio of the distance

from the coiling axis to the umbilical edge of the penultimate chamber

(Si) to total to gi+gj, the width between umbilical edge of the penultimate chamber and the chamber's peripheral edge (Fig. 10).

SERIAL DISSECTIONS

Methods

The procedures for preparing specimens for serial dissection and

SEM analysis were modified from methods described by Huang (1981). A

small amount of xylol-free Canada balsam is evenly sprinkled on the surface of an SEM stub that is placed on a small lead block and heated on a hotplate at 140°C. When the balsam begins to melt, several drops of xylene are added until the mounting medium homogenizes into a 45 smooth coating about 0.5 mm thick. The stub is removed from the heat after about two minutes. Once cooled, the consistency of the balsam is tested in several areas by the pressure of a needle. The stub must be reheated if the cooled balsam is still soft, otherwise mounted specimens will move while being dissected. About 25 specimens are placed on the hardened balsam and aligned in several rows with their coiling axes perpendicular to the stub surface. The stub is then reheated to 150°C while viewed with a microscope. At this temperature, the balsam is too viscous to penetrate the walls of porous specimens, but soft enough to partially emplace the specimens in the medium by lightly pressing with a fine needle. If the specimens sink too far in the embedding medium or become infilled with balsam, they can be reheated, removed with a needle, and cleaned in a small vial of acetone. The stub is removed from the hotplate after all specimens are adjusted to their proper orientation.

Specimen dissection was made easier by using a homemade "universal stage". This stage was fabricated by filling a hollow 2" sphere with epoxy, cutting it in half after the epoxy hardened and placing the half sphere on a screw-on plastic lid of sufficient size and texture to allow the flat surface of the half sphere to be rotated to a near vertical position without slippage. The lid was glued to a flat piece of plexiglass which in turn was glued to the top of a laboratory jack stand. A 1/8" hole was drilled 3/8" deep in the center of the half sphere to accomodate the stem of an SEM stub.

Tests are dissected with a fine needle, sharpened to a wedge about ten microns in width. The needle is mounted on the end of a Sensaur1" 46 micromanipulator, which affords precise three-dimensional movement,

enabling dissection of chambers as small as 10 microns in diameter.

Foraminifer tests are dissected under a light microscope with the wedged needle oriented parallel to the plane of the axial periphery.

After each whorl is dissected, the specimens are cleaned in a ultra sonic bath and prepared for SEM study. High-spired specimens are the most difficult to dissect as the walls of the adult chambers obscure the view of the test interior. Care must be taken to avoid cutting chambers in the initial whorls beyond their maximum diameter so that accurate measurements could be obtained.

The most tedious aspect of this dissection method arises with serial dissection and SEM study of single specimens. In order to characterize their complete morphology, the umbilical, spiral and edge views of external morphology are recorded by SEM, then each specimen is mounted in balsam. Specimens chosen for dissection were previously x-rayed to confirm that the test chambers were not infilled.

Microradiographs of dissected specimens also provide a means of determining the maximum cross-sectional chamber sizes for specimens dissected beyond the maximum axial periphery. The specimen is photographed on the SEM after each whorl is removed until complete dissection is achieved. If the specimen is damaged during any stage of this process , the goal of illustrating the complete ontogeny of a single specimen cannot be reached. Therefore, several specimens of the same species were dissected at a time to improve the odds for complete success.

Morphometric information from the initial whorl was most rapidly 47

obtained by completely dissecting up to 25 specimens on a single SEM

stub immediately after being embedded, without the repeated SEM

photography subsequent to each whorl removal. The most cost- and

time-efficient way to record the information from the dissected

populations is by photographing with a 35 mm camera mounted on the

SEM. Morphometric parameters can then be easily measured on proof

sheets of the SEIM images with the light microscope and the biometrics

equipment described above.

Morphometric Parameters

Serial dissection of ventral chamber walls facilitates

identification of pre-adult growth stages inside the foraminifer

tests. The exterior of the early formed chambers provides several

Important criteria that can be used for supraspecific assignment.

These include the 1) degree of chamber compression, 2) angularity of chamber sutures, 3) changes in apertural position, and 4) surface ornament of the outer walls of interior chambers. Two types of

interior morphologies are recognized in this report: 1) hedbergellid

forms with axially compressed chambers that increase slowly in size, extra-umbilical apertures, smooth to finely pustulose wall surfaces, and radial to slightly angular sutures, and 2) globigerine forms with globular chambers that increase moderately to rapidly in size, umbilical-extraumbilical apertures, finely to coarsely pustulose wall surfaces, and radial sutures.

Brummer et al. (1987) cautioned that secondary calcification of earlier formed chambers may obscure their primary surface structure, 48 producing a smoothened surface ornament on the outer wall of interior chambers and a loss of test porosity. The presence of spines and pustules on early formed chambers, however, is considered a primary feature as these are not added after initial chamber calcification

(B6, 1979).

Morphometric parameters measured from the initial whorl of planktonic specimens in this study include the 1) proloculus (earliest formed chamber) diameter, 2) initial whorl diameter, and 3) initial whorl chamber number (Fig, 11), Only microradiographs of Hedbergella sliter!. a nearly evolute species, recorded accurate detail of the initial whorl chamber sutures. Therefore, the number of measurements for this species (51) far exceeds those for serially dissected specimens, which generally number less than 20 (Table 2).

Serial dissections also enable an accurate count of the maximum number of chambers in each species. Secondary calcification on the earliest chambers of trochospirally coiled planktonic specimens often smooths or obscures externally exposed chamber sutures, particularly in coarsely ornamented taxa, causing uncertainty in determining the total chamber number from the external view.

Changes in the rate of test size increase during the ontogeny of planktonic foraminifers were the basis for recognizing different stages of growth in modern populations of Globiperinoides saccullfer.

£. ruber. and £. aeauilateralis (Brummer et al., 1987). A measure of the increase in cross-sectional chamber area per successive chamber is proposed in this study as a more accurate means for characterizing ontogenetic changes in test size. This two-dimensional approach 49

accounts for changes in chamber size and shape, whereas the measure of

test length only recognizes growth increase in the direction of

coiling.

CRITERIA FOR TAXONOMIC CLASSIFICATION

CONVENTIONAL CLASSIFICATION SCHEMES

The standard approach to taxonomic classification of planktonic

foraminifers has been based primarily on observations of external

features of the foraminifer shell. A recent example of the hierarchy

of morphologic characters used by most workers to classify Upper

Cretaceous trochospiral genera was presented by Caron (1985, Fig. 1) and is reproduced in Fig. 8. The highest taxonomic categories are divided using the position of the primary aperture. These categories are then subdivided, in order of decreasing taxonomic rank, by the presence of supplementary apertures on the umbilical side, the type of protective cover of the aperture and umbilicus, the presence (and number) or absence of peripheral keels or an imperforate peripheral band, the exterior ornamentation of the chamber surface, and the character of umbilical sutures.

The classification scheme used by Caron (1985) and the European

Working Group on Planktonic Foraminifera (Robaszynski et al., 1984) works well for adult Upper Cretaceous planktonic assemblages from low

to middle latitude, normal marine environments. However, this classification is more difficult to apply to adult-poor populations deposited in shallow marine sediments or other depositional environments where fecundity was suppressed (such as strongly seasonal 50

high latitude oceans). Small (<150 microns), pre-adult forms that

dominate highly variable surface water environments bear little

resemblance to their adult counterparts (e.g., see Brummer et al.,

1986, 1987). Adult characters used to classify Upper Cretaceous

species, such as peripheral keels, umbilical cover plates, raised

sutures and meridionally aligned costellae, are not well developed until the later stages of foraminifer ontogeny. Because of this, many workers tend to ignore the <150 micron fraction of fossil samples to avoid taxonomic uncertainties.

Small planktonic foraminifers could not be ignored in a nearshore, clastic marine sequence of upper Campanian-Haastrichtian age exposed

In the James Ross Island region, where age diagnostic species are lacking. Some forms from that sequence exhibit faint meridional alignment of costellae, characteristic of the genus Rugoelobigerina. but the slightly extra-umbilical position of the aperture and absence of umbilical cover plates suggest classification in the genus

Hedbereella (see Huber, 1988, p. 207, Figs. 29.1-29.11, 30.5-30.17).

Although identical forms were illustrated from the Falkland Plateau

(e.g., PI. I, Figs. 6-11), their taxonomic identification was judged incorrect (see previous discussion). Recognition that those forms represent pre-adult or kummerform morphotypes of the same species (PI.

II, Figs. 1-8) was possible only after ontogenetic morphometric analysis of populations classified in this study as Archaeoglobigerlna australis n. sp. (see discussion below). 51

ONTOGENETIC MORPHOLOGY

Pessagno (1967, p. 250) stated that "Any study made of Upper

Cretaceous planktonic Foraminifera based on external characteristics

alone is hazardous [because] homeotnorphy or near homeomorphy is common

among many species...at least when they are studied on the basis of

their external morphology alone." Because the SEM was unavailable

during preparation of Pessagno's monograph on Upper Cretaceous

planktonic foraminifers from the Gulf Coast, he relied on thin

sectioning techniques to facilitate identification. As this method is

time consuming and provides only a two-dimensional view of individual

specimens, it was never widely used by other planktonic foraminifer

researchers.

Few subsequent studies have realized the potential wealth of

information revealed by morphometric study of planktonic foraminifer ontogenies. Huang (1981) pioneered the test dissection and SEM

analysis method, but without a precisely guided dissection tool, his study was limited to few specimens of different modern and Neogene

species groups; population statistics information was not presented.

Brummer (1986) and Brummer et al. (1987) followed Huang's approach by combining information from test dissections of adult specimens with study of pre-adult forms that were recovered from plankton tows.

Population statistics cited in that study were primarily obtained from whole specimens rather than test dissections. Sverdlove and B£ (1985) described a method for obtaining ontogenetic morphometric information

from light microscopic study of specimens embedded In plastic. Their

approach can only be used for modern or exceptionally well preserved 52

specimens with transluscent tests, however. Thus, the database for

comparison of morphometric parameters derived from serial dissection

of fossil planktonic foraminifers is very limited and, until this

study, is entirely lacking for Cretaceous planktonic foraminifers.

Several authors (e.g., Cifelli, 1969; Hart and Bailey, 1979;

Wonders, 1980; Cifelli and Scott, 1987) have noted the iterative

nature of planktonic foraminifer evolution. Repeated architectural

features have been related to structural function and adaptive

strategies to achieve depth positioning within the surface waters

(Hart, 1980; Caron and Homewood, 1983). Occurrence of some

homeomorphic characters has caused confusion in Upper Cretaceous

taxonomic classification schemes. For example, the species

Costellagerina pilula (Belford) was originally placed in the genus

Rueoglobigerina because of the meridional pattern of costellae

alignment (e.g., PI. Ill, Figs. 2, 5-7, 11). However, Belford (1983) observed that the absence of an umbilical cover plate and the earlier

(Santonian) stratigraphic range of this species was not consistent with the original definition of genus Rugoelobigerina. Petters et al.

(1983) subsequently erected a new genus, Costellagerina. to include pre-Campanian meridional costellate forms with rugoglobigerine test morphologies lacking umbilical cover plates.

Comparison of microradiographs and serial dissections of topotype specimens of C. pilula (PI. Ill, Figs. 1-11) and Gulf Coast specimens of RugoglobieerIna rueosa (Plummer) (PI. IV, Figs. 1-15) demonstrates major differences in their ontogenetic morphology that are not apparent in exterior views. The mean number of chambers in the PLATE III. Serial dissections and x~radiographs of topotype specimens of Costellaeerina pilula (Belford), Toolonga Calcilutite, Pillarawa Hill, Western Australia, sample 71640043. Figs. 1*4. Four chambered morphotype previously recognized as Costellaeerina bulbosa (Belford) by Petters et al. (1983) and Rugoelobigerina bulbosa Belford by Belford (1960) (216 pm). Figs. 6-10. Larger, 5.5 chambered morphotype (348 pm). Figs. 11-13. Five chambered morphotype (288 pm). Morphologic similarity of the ontogenies revealed by serial dissection of the four, five and 5.5 chambered morphotypes suggests these are ecophenotypes of a single species. C. pilula is retained as the name bearer of these forms. Measurements in microns in this and the following plates refer to the maximum test diameter unless otherwise stated,

PLATE IV. Juvenile and adult specimens of Rugoalobieerlna rueosa (Plummer) from the upper Maastrichtian Kemp Clay (Texas) near the location from which this species was originally described. Figs. 1-5. Exterior, microradiograph and interior views of a juvenile specimens (220 pm) . The juvenile morphology is characterized by the poor development of meridional alignment of costellae on the antepenultimate and earlier chamber surfaces and the continuing rapid rate of chamber size increase in the final whorl. Fig. 6. Complete serial dissection of a juvenile specimen (218 pm). Fig. 7, Enlarged view of a well developed tegillum on the juvenile specimen shown in Figs. 1-5. Figs. 8-13. Exterior, microradiograph, and interior views of a adult specimen (424 pm). Note that the chambers in the final whorl show well developed meridional costellate ornamentation and a diminished rate of size increase. Figs. 14-15. Complete serial dissection of adult specimens. 14: 435 pm, 15: 414 pm. Note the somewhat reniform morphology of the initial whorl chambers. These initial whorl morphologies are identical to the juvenile morphology shown in Fig. 6.

57 penultimate whorl, determined from 67 x-radiograph images, is 5.57 for

C. pilula whereas the mean value for R. rueosa is 6,90 for 62 specimens analyzed (Table 1). The mean number of chambers in the initial whorl, revealed after complete test dissection, is 5.62 for 18 specimens of C. pilula. whereas an average of 6.90 was present for £. rugosa (Table 2). Although dimensions of the initial whorls are similar in populations of both species, other characteristics of the pre-adult chambers show considerable differences. These are discussed in greater detail in the following section.

MORPHOMETRIC PARAMETERS

Results from Test Exterior Observations

Utility and Limitations. The main advantage of the x-ray method in morphometric analysis of foraminifers is the ease and rapidity with which large data sets can be generated. Statistical differences in the number of chambers within the penultimate whorl, chamber size parameters and position of the generating curve can readily be determined for different species populations of several hundreds to thousands of specimens. The microradiographs also show accurate detail of ontogenetic changes in chamber and whorl suture morphology particularly among the more evolute coiled taxa. An additional benefit is that the internal morphology of sufficiently preserved holotype or paratype specimens can be observed without recourse to test dissection or thin sectioning. Furthermore, the cost of obtaining the microradiographs is generally limited to the price of the film used, as the necessary equipment is available at most 58

research institutions.

This method can not be applied to specimens with coarsely

ornamented, heavily encrusted, or infilled tests, as these are opaque

to x-rays, and thus the chamber sutures cannot be differentiated. In addition, several morphometric parameters are difficult to measure in high-spired specimens because of the weak images produced by strongly overlapping chambers. Chamber overlap prevented accurate total chamber number counts and measurement of morphocharacters within the initial whorl in all but the most evolutely coiled taxa. Attempts at measuring ontogenetic changes in cross-sectional chamber area from the x-ray images were abandoned because of obscured chamber sutures and uncertainty in the position of the measurable chambers within the ontogeny.

The number of specimen measurements needed to sufficiently characterize planktonlc foraminifer populations depends on the morphologic variability of each species. For example, the mean number of ultimate whorl chambers was 5.28 for the first 20 measurements of

Hedbergella sliteri n. sp., a morphologically conservative species, and 5.34 for the total population of 52 specimens (Table 1), a difference of less than 2%. In contrast, the mean of the first 20 measurements of Archaeoglobieerina austral is n. sp., which shows considerable morphologic variability, differed by 6 % from the mean for

52 specimens. The mean for 42 more specimens of australis changed by only 1% from the values obtained for 52 specimens.

Ultimate whorl chamber number. The number of chambers that occurs in the final whorl is a function of the height of the coiling axis and 59

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«3 5 B M M H 15 u CU3 * S£3 B 8 8 & s 8 * a *Valuaa *Valuaa includa tha ‘Thia population atudy; ’Kubax, maan, 19BS; Yraahaninnikov atandard deviation (in paranthaaaa). and minimum to maximum rang*. Onlta of maaaura in mlcrona. 60

the rate of chamber size increase. Taxa with a low spire and a slow

rate of chamber size increase, such as G1obotruncana cretacea and

Hedbergella sliterl. will have a higher mean value for this parameter

than high spired forms with early chambers that increase rapidly in

size, such as A. bosauensis (Table 1). Variability of this parameter

is highest for A. bosquensis and A. mateola. which both tend to form

final chambers that strongly overlap previous chambers or the

umbilical region. Differences in standard deviation values of this

parameter among the species analyzed (Table 1) show that the degree of variability can be used as an additional criterion for taxonomic

comparisons.

Coiling direction frequencies. The frequency of dextral versus

sinistral coiling direction has been shown to strongly correlate with

temperature among modern and late Neogene populations of Globigerina bulloides d'Orbigny and Neogloboauadrina pachyderms (Ehrenberg), with an Increase in sinistral forms with decreasing temperature (Malmgren and Kennett, 1972, 1976). However, other modern species, such as

Globigerinoides sacculifer (Brady) and Globieerina falconensis Blow, have random coiling directions with no correlation to any measured physical environmental parameters (Be, 1977; Malmgren and Kennett,

1977).

Most species in this study had a dominantly dextral coiling direction (Table 1), with two species, G. cretacea and £. rugosa. approaching 100% dextral coiling. On the other hand, populations of

£• Pilula and £. sliteri have nearly equal abundances of dextrally and sinistrally coiled forms. Intraspecific variability of this parameter 61

Is demonstrated by A. australis. which has an 87% frequency of dextral forms among juvenile (<200 microns in diameter) populations at DSDP

Site 511, 76% dextral forms in adult populations from the same sample, and 94% dextral forms for coeval populations from nearshore marine sediments on Seymour Island (Table 1). As the database for comparison of the intra- and interspecific coiling direction frequencies is lacking for these Upper Cretaceous species, the taxonomic or paleoenvironmental significance of these values cannot be demonstrated. Nevertheless, this parameter is easily measured for large population sets, and could prove useful for evolutionary or paleoenvironmental reconstructions among some taxonomic groups.

Kummerform frequencies. Final chambers that are reduced or equal in size to penultimate chambers in planktonic foraminifers are termed kummerform chambers (e.g., see PI. II, Figs. 4-8; PI. VII, Figs. 1-

17). Several authors (e.g., Berger, 1969; Hecht and Savin, 1970;

Malmgren and Kennett, 1976) attributed the formation of kummerform chambers to abnormal ontogenetic development caused by environmental stress. Alternatively, formation of these chambers has been related to genetic control incorporated in the planktonic foramlnifer growth plan (Olsson, 1971, 1973). In a study of laboratory cultured specimens of Globigerinoides sacculifer. a species that frequently grows kummerform ultimate chambers, Hemleben et al. (1987) found no relationship between the formation of kummerform chambers and changes in salinity, temperature, light, and nutrient availability. Their study supported the conclusion of Anderson and Faber (1984) that the morphology of the final chamber is primarily dependent on the amount 62 of calcium stored in cell organelles just prior to gametogenesis.

The frequency of kummerform specimens among the planktonic foraminifers in this study varies between and sometimes within the species groups (Table 1). Highest values are shown for bosauensls

(55%), mateola (78%) and juvenile forms of A. australis (66%).

Kummerform specimens were absent in Rueoglobieerina rueosa and were relatively rare in H- sliteri. £. pilula. and Seymour Island populations of A. australis. As with the coiling direction frequency, there is no database for comparison of kummerform frequency among these populations. Nonetheless, the characteristics of Seymour Island populations of A. australis suggest that this parameter is not an indicator of environmental stress. Much higher frequencies of kummerform individuals would be expected from the nearshore, clastic facies of Seymour Island than from the open ocean environment if kummerform chambers were stress-related morphocharacters, Mostly normalform specimens were recorded from the Seymour Island samples, whereas deep sea assemblages of A. austral is (DSDP 511) show a higher frequency of kummerform chambers (Table 1).

Test breadth/diameter ratios. The ratio between maximum test breadth and maximum test diameter (Fig. 9) is a function of the height of the coiling axis and the size of the chambers in the final whorl.

High spired morphotypes (e.g., A. mateola) or forms with axially broad chambers (e.g., R. rugosa) show a higher ratio than low spired forms with axially narrow chambers (e.g., G. cretacea and H- sliteri). The lowest degree of variability in this parameter is shown by H. sliteri

(std. dev. - 0.03) whereas A- mateola and R. rugosa show much higher 63

variability (std. dev, — 0,09) (Table 1),

Apertural height/width ratios. The ratio of apertural

height:width (Fig. 9) was measured only for those forms with extra-

umbilical apertures. Results show a ratio near 1:1 for pre-adult

forms of australis but a much lower ratio for H. sliteri (Table 1).

Position of the generating curve. The position of the generating

curve, originally defined by Raup (1966), is shown on Fig. 10 as the

ratio of the distance from the coiling axis to the umbilical edge of

the penultimate chamber (gj) to the total distance from the coiling

axis to the penutlimate chamber axial periphery (gj + g2) . The

penultimate chamber is used rather than the ultimate chamber to avoid

bias from occurrences of kummerform specimens. These values reflect

the width of the umbilical region and the degree of axial compression

of the penultimate chamber. The lowest mean values (0.19) were

obtained from 4 . bosauensis and A. mateola. both of which frequently

show tight coiling about a high axis. R. rugosa shows a relatively

low value (0 .2 1 ) because of its axially broad penultimate whorl

chambers (Table 1). The mean values and standard deviations for the

remaining species show strong overlap, and therefore, this parameter

is not used as a distinguishing criterion for these taxa.

External ornamental features. Surface ornament features, such as

the size, density, and alignment of pustules, are used in taxonomic classification schemes to differentiate suprageneric categories of planktonic foraminifers. Development of these features, however, may vary with ontogenetic growth and significant variability may occur in

adult populations of the same species. For example, the first two 64 chambers in the final whorl of small (juvenile) specimens of R. rugosa have no evidence of meridional alignment of pustules or costellae (PI.

IV, Figs. 1-3), whereas a larger (adult) form has very well developed meridionally aligned costellae on all four chambers of the final whorl

(PI. IV, Figs. 8-10). Juvenile forms of A. austral is typically have finer development of surface pustules than the adult forms (e.g., compare juvenile forms on PI. VII, Figs. 1-3 with adult forms on PI.

IX, Figs. 1, 5-7, 11-12, 18).

Intraspecific variability of surface ornaments, particularly the presence of meridionally aligned costellae, which is unique to several

Upper Cretaceous planktonic foraminifer taxa, is apparent among populations of several species analyzed in this study. Costellae alignment may occur on all final whorl chambers of C. pilula (PI. Ill,

Fig. 2), on only the spiral side of the chambers (PI. Ill, Figs. 5-7), or be poorly developed on all of the final whorl chambers (PI. Ill,

Fig. 11). The costellae on all specimens of C. pilula differ from those of £. rueosa by occurring as discontinuous, rather than continuous, ridges. Specimens referred to as Archaeoglobigerina cf.

A. australis show faint meridional alignment on one (PI. VI, Fig. 1) or several (Pi. IX, Fig. 1) chambers. On the other hand, typical forms of australis show a completely random arrangement of pustules

(PI. I, Figs. 6-27; PI. VIII, Figs. 5-7, 11-12, 18). Belford (1983) and Petters et al. (1983) considered formation of surface pustules and meridionally aligned costellae to have been genetically regulated, but

Blow (1979) suggested that phenotypic variation in the expression of these features may have been environmentally regulated. 65

The occurrence and kind of apertural covers, in the form of portici (apertural flaps) or tegilla (umbilical cover plates), are also used as important criteria for distinguishing taxonomic groups of planktonic foramlnifers (Fig. 8 ). These features, also unique to

Upper Cretaceous planktonic foraminifers, are thought to have evolved as a means of protection of the protistan cell from predation (Blow,

1979). The presence of tegilla is one of the unifying characteristics used to classify species in the Globotruncanacea, which includes species of Archaeoglobigerina. Rugoglobjgerina. and Globotruncana

(Fig. 8 ). Well developed tegilla extend from above the aperture of the final chamber across the umbilicus to the umbilical edge of several previous chambers (Pi. IV, Figs. 1, 7, 8 ). Absence of tegilla from type specimens of Archaeoglobigerina was attributed by Pessagno

(1967, p. 315) to imperfect preservation, but it is important to note that no specimens of the earliest species of this genus, &. bosauensls

Pessagno, have been illustrated with this umbilical feature.

Furthermore, specimens identified as A. bosouensis and £. cretacea from Santonian sediments on the Falkland Plateau (Sliter, 1977;

Krasheninnikov and Basov, 1983) lack any evidence for the presence of tegilla, despite their excellent preservation (PI. 10, Figs. 1*10; PI.

I, Figs. 1-8).

Weakly developed "tegilla" were rarely found on specimens designated as &. cf. A. australis from Seymour Island (PI. VI, Fig. 1 ) and the Falkland Plateau (PI. IX, Figs. 1, 4). Portici are common in specimens of £. australis (Table 1), occurring as narrow extensions of an apertural lip (PI. VII, Figs. 1, 11, 14; PI. VIII, Figs. 1, 5, 9, 66

13; PI, IX, Figs. 11, 18) or an elongate flap (PI. VI, Fig. 8 ; PI.

IX, Fig. 5). Considerable variability in expression of the apertural cover plates suggest that this feature is not always a reliable criterion for taxonomic classification.

Results of Microradiograph Observations

Utility and limitations. The main advantage to the x-ray method for morphometric analysis of foraminifers is the ease and rapidity with which large data sets can be generated. Statistical differences in the number of chambers within the penultimate whorl, chamber size parameters and position of the generating curve can readily be determined for different species populations of several hundreds to thousands of specimens. The x-ray micrographs also show accurate detail of ontogenetic changes in chamber and whorl suture morphology particularly among the more evolute coiled taxa. An additional benefit is that the internal morphology of sufficiently preserved holotype or paratype specimens can be observed without recourse to test dissection or thin sectioning. Furthermore, the cost of obtaining the microradiographs is generally limited to the price of the film used, as the necessary equipment is available at most research institutions.

This method could not be applied to specimens with coarsely ornamented, heavily encrusted, or infilled tests, as these are opaque to x-rays and thus the chamber sutures cannot be differentiated. In addition, several morphometric parameters are difficult to measure in high-spired specimens because of the weak images produced by strongly 67

overlapping chambers. Chamber overlap prevented accurate total

chamber number counts and measurement of morphocharacters within the

initial whorl in all but the most evolutely coiled taxa. Attempts at measuring ontogenetic changes in cross-sectional chamber area from the x-ray images were abandoned because of obscured chamber sutures and uncertainty of where in the ontogeny the measurable chambers were positioned.

The number of specimen measurements needed to sufficiently characterize planktonic foraminifer populations depends on the morphologic variability of each species group. For example, the mean value for the number of ultimate whorl chambers was determined as 5.28 for the first 20 measurements of Hedbergella siiteri n. sp., a morphologically conservative species, and 5.34 for the total population of 52 specimens (Table 1), a difference of less than 2%.

On the other hand, the mean value of the first 20 measurements of

Archaeoglobigerina australis n. sp., which shows considerable morphologic variability, differed by 6 % from mean values obtained for

52 specimens. The mean values for 42 more specimens of australis. changed only by 1% from the values obtained for 52 specimens.

Penultimate whorl chamber number. Most species analyzed have a higher mean number of chambers in the penultimate whorl than in the final whorl chamber number (Table 1). This is particularly the case for £. pilula and R. rugosa (PI. Ill, Figs. 9, 12; PI, IV, Figs. 4,

1 1 ), which have an average of one more chamber in the penultimate whorl than in the ultimate whorl. Only G. cretacea has a lower mean number of chambers In the penultimate whorl. Although this parameter 68 has never been used for taxonomic comparisons, these results suggest that it can be a useful criterion for distinguishing between some species.

Penultimate/antepenultimate chamber ratios. This parameter is a measure of size increase in the final whorl of planktonic foramlnifer tests. Mean values for C. pilula and iJ. sliteri. 1.16 and 1.18, respectively, indicate that the penultimate chamber size increases by more than 20%, whereas the 0.99 mean value shown for G. cretacea indicates no increase in chamber size after the antepenultimate chamber (Table 1). The mean values for all other species fall within one standard deviation of each other and, thus, these species cannot be distinguished using this parameter.

Results from Serial Dissection Observations

Utility and Limitations. Serial dissections of ventral chambers coupled with SEM analysis are the best methods for characterizing morphologic changes that occur during the ontogeny of trochospirially coiled fossil planktonic foraminifers. Attributes of the pre-adult morphology exposed during test dissection provide a whole new suite of morphocharacters that can be used to supplement observations of the test exterior. The value of this information for improved taxonomic classification is demonstrated in this study, as is the potential for improved phylogenetic and paleoenvironmental reconstructions.

The disadvantage of this method is that it is a slow, laborious process requiring equipment not available at many institutions.

Careful dissections of the small, interior chambers of numerous 69 specimens could not have been made without the micromanipulator, a specialized and expensive tool. In addition, the amount of SEM work needed to complete each species analysis adds to the expense of this technique. This dissection method can be applied to specimens that are permeated by unconsolidated sediment, which can be ultrasonically removed, but it cannot be used on specimens infilled with lithified materials.

As with the X-radiographic method, the number of specimens needed to adequately characterize planktonic foraminifer populations using morphometric parameters derived from serial dissections depends on the degree of variablity within each species group. One species,

Archaeoglobiperina mateola n. sp., shows a bimodal distribution of proloculus and initial whorl diameters (see below), but this was only recognized after measurement of the first nine dissected specimens.

Addition of the two megalospheric specimens to the data set of 16 microspheric proloculus diameters changed the population mean by 9.2%.

This total is considered insufficient for an accurate representation of whole population variability. On the other hand, the proloculus diameter means of a less variable species, Costellaeerina oilula

(Belford) changed by less than 2% after eight specimen measurements were added to the first ten. Data sets of less than 20 specimens presented in this study can be used for preliminary interpretation, but more specimens should be measured to provide a more statistically reliable base for comparison.

Proloculus diameters. Proloculus and initial whorl diameters vary consideraby for all species analyzed in this study, as depicted on the TABU 2. HoipKoMtrlc And obitm U ontl data obtained from planktonic foraminifar aarial diaaactiona. SPECIES Arehaaogiob. Arehaaogi ob. Archaaoglob. Archaaogloh. Arcbaaoglob. Arehaaogiob. Coatallag. Rugoglob. Roctbarg. auatralla australis auatralla botqbantlt cratacaa aiataola pllula rugoaa alitan ()uvanila) (adult) (adult)

LOCALITY DSDP 511, DSDP 511, ODP 113 DSDP 511, DSDP 511, DSDP 690C, Ha atarn Taxaa DSDP 327A 23-1, 67-69 23-4, 67-69 20-3, 116-118 42-5, 34-4, 1-3 Auatralia 10-3, 22-24 ASK aarly aarly aarly Santonlan’ Campanian1 middla Santonlan1 Haaatrlcht.' aarly Haaatrlcht.1 Haaatrlcht.1 Maastricht.1 Haaatrlcht. ‘ Haaatrlcht

NUMBER 01 18 34 19 23 16 16 18 19 51 OBSEBV.

PROLOCULUS 13.9 15.1 16.62 15.3 19.8 17.4 14.5 15.3 16.9 DIAMETER (28) (l.») (1.62) (2.0) (2.3) (4.5) (1-1) (1.9) (1.8) 10.4-22.0 12.6-1B.7 14.1-21.4 12.3-19.4 16.2-23.4 12.7-27.8 12.6-17.1 10.9-18.5 13.6-20.3 IMIT, MHORL 61.1 71. B 71.7 74.9 92.2 74.1 67.6 62.7 74.3 DIAMXTIR (13.8) (7.9) (7.4) (122) (9.3) (18.8) (6.0) (7.8) (11.2) 41.2-91.3 61.8-93.2 58.9-83.2 50.4-95.8 77.1-115.2 51.6-117.0 57,4-78.2 57.4-7B.2 53.6-99.7

IMIT. MHORL 4.69 4.38 4.25 4.36 4.57 4.48 5.42 5.42 5.03 CHAMB NO. (0.33) (0.27) (0.19) (0.22) (0.28) (0.25) (0.33) (0.33) (0.16) 4.00-5.25 3.75-5.00 4.00-4.50 4.00-4.75 4.00-5.00 4.00-5.00 4.75-6.00 4.75-6.00 4.75-5.25 IMIT. MHORL Hadbargall. Hadbargall. Hadbargall. Hadbargall. Hadbargall. Hadbargall. Hadbargall. Hadbagall. Hadbargall. CHAMB.

IMIT. MHORL Smth. to fn. Smth. to £n . Smth. to fn. Smth. to fn, Smth. to fn. Flna Smooth Fina Smooth CHAMB. ORN puatulaa puatulaa puatulaa puatulaa puatulaa puatulaa puatulaa

PENULT. MHORL Globigarina Sloblgarlna Sloblgarlna Sloblgarlna Sloblgarlna Sloblgarlna Hadbargall. Sloblgarlna Hadbargall. SHARK

PENULT. MHORL tlna Tina Flna Fina Flna F n . to mad. Smth. to fn. Fn. to mad. Smth. to fn CHAMB. ORN. puatulaa puatulaa puatulaa puatulaa puatulaa puatulaa puatulaa puatulaa puatulaa EXTERN. MHORL lino Coataa Coaraa Coaraa Hod. puatula Cra. puatula Harldional Harldional Smth. to fn SORT. ORM. puatulaa puatulaa puatulaa puatulaa £n . kaalad lg. aplnaa coatallaa coatallaa puatulaa

MAX. CHAMB. 11 16 15 14 17 16 19 16 16 HUMBER

'Valua* lncluda population naan, standard daviation (in paranthaaa*), and minimum to maximum rang*. Unit a of maaaurwnant In mlcrona. ’Ttila study; 'Kraahaninnikov * Baaov, 1983; *Balford, 1960; ‘Paasagno, 1967. Figure 12. Scatter plots and least squares regression of proloculus and initial whorl diameter measurements for seven Upper Cretaceous species of planktonic foraminifers. Most species show strong correlation between these two parameters. Note the wide scatter of points shown by juvenile specimens of Archaeoglobigerina australis and the strongly bimodal point distribution portrayed by Archaeoglobigerina mateola. Least squares regression line equation, correlation coefficient (r) and number of measured spe imens (n) are presented for each species.

71 Initial Whort Diamatar (microns) Initial Whorl Diameter (microns) Initial Whort Diamatar (microns) 100 5 1 1 0 1 1 110 100 - 5 0 1 - 5 1 1 r- 120 105 120 5 0 1 110 120 100 0 9 5 4 5 6 5 8 0 5 5 6 80 5 4 0 6 5 6 80 0 6 90 5 5 5 7 60 0 9 5 9 45 5 6 85 - - Proloculus Diamalsr (microns) Diamalsr Proloculus iue 12. Figure Archaeogiobigenna bosquensis Archaeogiobigenna 12 Archaeoglobigerina australis Archatoglobtgerina australis Archaeoglobigerina austra/ts Archaeoglobigerina australis Archatoglobtgerina australis Archaeoglobigerina SPSl 1 (juvenile) 511 Silo DSOP Toolonga Caldlutite Toolonga 14 6 1 SPSl 511 Sile OSOP 16 m . i u i - i 1 . y - 4 0 4 i « 1264 1264 « i 4 0 4 - y }«2N * N 2 « ,} y 23 n - M V . f rt-21 K O • ( 1 18 18 U n - 20 n - U 20 20 9 22 22 19 8 2 4 2 6 2 6 2 8 2 0 1 1 0 0 1 5 0 1 115 0 2 1 5 1 1 5 0 1 110 100 100 5 0 1 5 1 1 no 120 5 8 5 4 5 9 0 8 0 5 5 6 5 5 0 7 0 9 0 6 - 0 6 so 75 0 9 0 6 0 6 0 6 5 7 5 9 5 7 4 1 6 2 2 2 18 14 0 Protoculua Diamatar (microns) Diamatar Protoculua - - - - 5 8 ------■ -g - - - 2 16 20 24 28 2 4 2 0 2 6 1 12 Archaeoglobigerina mat mat cola Archaeoglobigerina ■ « \ / _ DSUK 5 « e 5 > 4 1 14 r j i SP ie 511 Sile DSDP j r-2«ta* 1724 r-2«ta* */* * a Kemp Clay Kemp 3 9 S t * 2 9 I - r r . 0 7 l n » n l 7 0 . r 4 9 0 - r y-*47jc t / r - 0 77 n - 19 n - r 770 - ■ a 20 n • 1 13 «U 0 2 22 1 22 l&OUUf 4 2 6 2 /

29 - 0 0 1 5 1 1 0 1 1 5 0 1 0 2 1 5 0 1 100 110 5 1 1 100 5 1 1 110 120 105 5 9 5 5 0 9 0 6 5 4 5 4 - 0 8 0 5 5 6 0 7 5 7 00 0 9 5 9 5 5 so 0 5 0 6 0 9 5 4 Proloculus Diamatar (microns) Diamatar Proloculus 0 1 - * ------Globotruncana cretacta Globotruncana 2 1 8 2 4 2 0 2 16 12 12 12 SPSt 511 Sit© DSDP 8 22 26 2 2 2 18 4 1 4 1 Itedkergella sitieri Itedkergella DSDP Sits 511 Sits DSDP 16 uur *«« 1 DO 1 « « * 4 » f I S . n 4 1 . 1 ai r * 0 9 0 n - Iff - n 0 9 r 0 * 18 bite t»yu 20 20 22 22 24

6 2 29 72 73

2 0

£ 15

10 8 3 E I tf

120-1

g too V £ X 1 x: so ▼ o V x X o £ oo c

40 MM

Figure 13. Univariate plots of mean, 1 standard deviation about the mean, and total size range for proloculus and initial whorl diameters for the planktonic foraminifers analyzed in this study. Three population sets of Archaeoglobigerina australis were measured, including juvenile (juv.) and adult specimens from DSDP Site 511 and adult specimens from 0DP Site 690. Fig. 5 shows the number of specimens measured for each species. 74

bivariate scatter plots of Fig. 12. The mean, standard deviation, and

total range of proloculus and initial whorl diameters are plotted on

Fig. 13 and are listed in Table 2. Mean values for most species fall between 14 and 17 microns. The only exceptions to this are proloculus

diameter values obtained for G. cretacea. which average about 20 microns. Minimum diameters of 11 microns occur in specimens of A.

australis and R. rugosa. whereas maximum diameters of (3. cretacea and

A. mateola are well over twice those minimum values. Specimens of £. ollula show the least variability, with a standard deviation value of

1.1, whereas specimens of A. mateola and juvenile forms of A, australis are more variable, with standard deviation values of 4.5 and

2.7, respectively. In fact, the scatter plot of proloculus and

initial whorl diameters of A- mateola (Fig. 12) has a strongly bimodaldistribution, with most values ranging between 14 and 17 microns and two values of about 28 microns.

Several authors have demonstrated the wide intraspecific variability in proloculus diameters among modern populations of

Globiperinoldes (Brummer et al, 1987) and several other living planktonic foraminifer species (Huang, 1981; Sverdlove and B6 , 1985;

Brummer et al., 1987). However, only broadly unimodal size distributions have been recognized, suggesting that alternation of sexual (microspheric) and asexual (megalospheric) generations does not occur among the planktonic foraminifera, In fact, Brummer et al.

(1987) proposed that the terms megalospheric and microspheric may not be applicable to globigerinid species. A predominant or exclusive sexual reproductive mode was suggested by Brummer et al. (1987), based 75

on prolocular measurements and the fact that asexual reproductive

modes have never been observed In laboratory cultures of planktonic

foraminifers. The absence of mean proloculus diameter values between

the two clusters In A. mateola (Fig. 12; see also Pi. I, Figs. 13-15)

may suggest alternation of generations in the life cycle of this

species, but serial dissections of more specimens are needed to verify

this bimodal distribution.

Although Huang (1981) used proloculus shape as a taxonomically

significant character, recognizing both spherical and ovular forms in

his dissected globigerinid specimens, Brummer et al. (1987) observed a

considerable range of intra- and interspecific variability in

prolocular shapes. The latter authors suggested that proloculus shape

depends on the degree of flattening of the wall between the proloculus

and deuteroconch, which is a function of the differential size of the

initial two chambers and the extent of initial calcification. Since

these factors have significant variability among living populations, proloculus shape is not used in this study as a criterion for comparing fossil species populations. Nevertheless, the studies of modern species and results of this study demonstrate inherent taxonomic significance in the mean values, total range, and amount of variability of proloculus diameters.

Initial whorl diameter. The range of intraspecific variability In the initial whorl diameters generally parallels that of the proloculus diameters (Figs. 12, 13). The highest standard deviations occur in £. mateola (18.8 microns) and juvenile forms of A. australis (12.3 microns) (Table 2). The latter forms also have the lowest initial 76

whorl diameter (41.9 microns) and while A. mateola has the largest

initial whorl diameter (117 microns). The mean for £. cretacea of

92.2 microns is significantly larger than the mean initial whorl

diameter of all other species analyzed, which predominantly range

between 65 and 75 microns.

Least squares regression lines plotted on Fig. 12 clearly reveal

the interdependence between the proloculus and initial whorl

diameters, particularly among adult specimens of A. australis. A-

mateola. C. pilula. and H. sliteri. For these species, the proloculus

size strongly controls the early ontogenetic test size. Lower

correlation coefficients between these two parameters are depicted for

G. cretacea. A. bosquensis. and R. rugosa.

A bivariate plot of the mean proloculus and initial whorl

diameters of each of the species and morphotypes measured in this

study also demonstrates a strong positive correlation (Fig. 14). The considerable difference in the mean diameters for G. cretacea is distinctly demonstrated, but differences between the other species are not apparent. Juvenile forms of A. australIs have the lowest mean values, indicating that proloculus and initial whorl diameters control the final test size of A. australis. Dissection of several Leg 71 juvenile kummerform morphotypes of A. austral is revealed a pronounced difference in initial whorl morphology (PI. VIII, Figs. 1-8), includ ing smaller proloculus and initial whorl diameters, compared with the normalform juvenile and adult specimens (PI. VII, Figs. 1-19; PI. IX,

Figs. 1-19). However, more juvenile kummerform morphotypes need to be examined to determine the taxonomic significance of this observation. Initial Whorl (microns) Archaeoglobigerina australis sp,,Archaeoglobigerina from n.DSDP 511,Site show thantheanyof otherspeciesvalues (juv.) and juvenile specimens of hw nFg 13.Fig.shown on forstandarddeveations proloculusinitial and are diameters whorl values Mean species.toeachaccurately characterize their ontenies, SeeFigure the5for numberspecimens of of measured 690.Site0DP o adRs (ODP113)forRiseMaud Leg specimens Indicating the species, sameof australis forobtainedadult normalformand kummerform specimensof htti i sflcieinfrtxnmccmaios The isthisthatacriterionforusefultaxonomic comparisons. lowersignificantly thanvaluesadult specimens from 511Site and DSDP fordiametersCretaceousUpper foraminifers planktonicInanalyzed from the (DSDPfromFalkland PlateauLeg 71) those areto close obtained hs td. Globo thist study. rune (d'Orbigny)anacretacea larger shows much mean 100 -i 100 70 - 80 - 90 - 60 -I 3 4 5 6 7 8 9 20 19 18 17 16 15 14 13 ------iue 4 Bivariateofplotmeaninitial proloculus andwhorl 14,Figure auatalia tra a u a . A 1 ------*• □ C. C. ft ft Hutm □ | ) O .) » (|u mut t i l tt f u m . A baun la boaauanm . A 1 ------□ □ a rlcls (microns) Proloculus (B 1 1 ) ) 1 1 (B ^ 1 ------auatalia tra a u a . A H.alttarl <«•<>> 1 ------m#ri 1 ------1 ------G. 1 77 78

Initial whorl chamher number. The size of the proloculus

influences the number of successive chambers that comprise the initial whorl. A larger proloculus size results in a more rapid Increase in

test diameter per successive chamber and fewer chambers in the initial whorl than occurs with a small proloculus (e.g., compare PI. VIII,

Figs. 4, 6 , 16 and 17). The number of chambers in the initial whorl closely compares with the penultimate whorl chamber number in species with less than two and one-half whorls (Tables 1-2). Specimens that have a greater number of whorls (e.g., G. cretacea) show more pronounced differences in these two parameters. This indicates that the number of chambers in the penultimate whorl, measured from microradiograph images, is not as accurate for species comparisons as is the initial whorl chamber number, since there is inconsistency as to where in the ontogeny this measurement begins. This uncertainty is further illustrated by comparison of standard deviations of the two parameters; a greater range of variability is shown for the penultimate whorl values than for the initial whorl. Nevertheless, important interspecific differences are apparent for both x-ray and serial dissection data sets.

The number of chambers in the initial whorl is lower than in the ultimate whorl among specimens of G. cretacea and H. sllteri (Table

2). More chambers occur in the final whorl of these species because of their tendency toward a more evolute chamber arrangement (PI. V,

Figs. 11-18; PI. I, Figs. 1-8). High mean values of initial chamber number were obtained for £. pilula (5.57) and R. rueosa (5.31) relative to to their final whorl chamber number, whereas the mean 79

values for A. australis. A. bosauensls. and A. mateola do not

significantly vary during their ontogeny.

Ontogenetic growth curves. Composite plots of mean and standard

deviation values of the chamber-by-chamber increase in cross-sectional

chamber area are portrayed as growth curves for each species

population in Figs. 15-17. C. pilula and H. sliteri have the most

gradual chamber size increase and the least variability in the final

chamber areas. The smallest final chamber areas occur in C. pilula.

bosauensls. and A. mateola. which generally range below 12,000

microns2. The largest final chamber sizes occur in G. cretacea and E-

rugosa. which reach 20,000 microns2 and higher (Figs. 16, 17). All

species of Archaeoglobigerina. which frequently have kummerform

ultimate chambers, have the largest standard deviations in final

chamber area. Variability in the final chamber areas of £. pilula and

H- sliteri is significantly less than for the other species since kummerform frequencies are much lower.

Logarithmic curves of the mean values for each morphotype are portrayed below the arithmetic graphs. In every morphotype examined,

the deuteroconch (second chamber) is smaller than the proloculus, as

shown by the negative slope between these two chambers. The

logarithmic curves are nearly linear for the following seven to nine chambers, suggesting a nearly constant rate of size increase. A subsequent break in the log-linear slope occurs at different successive chambers for several of the species examined (Figs. 15-17).

It occurs after the ninth chamber in adult specimens of australis and &. bosouensis. after the tenth chamber in E. sliteri. and after 80

Figure 15. Arithmetic and logarithmic plots of the chamber-by- chamber increase in cross-sectional chamber area of juvenile and adult specimens of Archaeoglobigerina australis n. sp. from DSDP Leg 71 and adult specimens from ODP Leg 113. The arithmetic plots show 1 standard deviation about the mean and the logarithmic plots show only the mean values. The number (n) of specimens analyzed are also shown. Log Mean Chamber Ana Mean Chamber Area i 4 14 25000 3000 i 1 1 i rhegoieia australis Archaeoglobigerina. - IS - n 1 j I 7 la n 1 ii i i 12 n a l > • 7 I j e iue 15. Figure 050P Leg 71 (juvenile) ubr f hmbers Cham of Number ubr f o ben hom C of Number r- r , 14 t i n —i 14 0 1 2 2 1 rhegoieia australis Archaeoglobigerina 1 n * 12 3 S 7 C 1 1 1 1 11 11 14 ] 1 11 11 !C I • 7 « S 4 4 I . SP e 7 (adult) 71 Leg DSDP ubr f Chambers of Number « 10 12 1 4 II 1 2 2 4 4 2 2 1 rhegoieia australis Archaeoglobigerina • 12 • n i Number Number 7 1 1 1 1) 4 9 | 1 19 14 ) 1 12 11 10 1 I 7 * N u m b e r o f C h a m b e r s I 10 I • O Lg 113 Leg OOP of I Chamber* ii t i u l t CO 82

Figure 16. Arithmetic and logarithmic plots as in Fig. 8 for three Upper Cretaceous planktonic foraminifer species. Smaller standard deviation values for the 16th chambers of Archaeoglobigerina mateola and G. cretacea results from fewer number of measurements rather than actual population trend. Log Moon Ctiombv Aroo Moon Chombor Ar*o 20000 10000 ArcfULQogiohigeTvna bosqueTisis - 18 - n ubr f Chamber* of Number ubr f Chamber* of Number iue 16. Figure SP e 71 Leg DSDP u u 1 rhegoieia mateola Archaeoglobigerina 1 i 4 7 » 0 11 10 » • 7 « 4 4 T of r) e b m a h C f o r e b m u N of n e b m o h C f o r e b m u N 0D 9 a 113 1 1 Lag T t \3 \t 14 3 1013 Xi Globatruncana cretacea Globatruncana ubr f a ben ham C of Number ubr f hmbers Cham of Number I to I I BS0P Ltg 71 J * L CD Log Ueon Chamber Area Utnn Chamber Area y y f * f y y y y y t \

4 4 3 Costellagerina pilula Costellagerina 3 ubr f hmbers Cham of Number Figure Figure olna Calcilutite Toclonga ubr f hmbon o b Cham of Number a io a a t t , 7

11 • tO • I 17. 1 9 4 9 f I 19 14 19 t I 11 ■ .. r— r—— i— I* y y T ,—,—r ? f T y y y -y i 3 a t i i ii i i ii io t a t i a ♦ 3 i i n . 13 uolbgrn rugasa Rugoglobigerina Number of Chambers Number of Chombem am a • ..if *p Day K*mp 1 t 13 1 r—i— + a ta ia i+ 1 — ■yyyy?f^i, i 2 3 * n * 21 * n ebrel sliteri Hedbergella > a ubr f a ben ham C of Number Number of Chomben SP e 71 Leq DSDP 7 a o i a is ia ii to a a • ia ii1 ,,,,,,, ^4 ii s ia is Ln OD 8U

Figure 17. Arithmetic and logarithmic plots as in Fig. 8 for three Upper Cretaceaous planktonic foraminifer species. See Fig. 9 for explanation of diminishing trend in final chamber standard deviation values. 86 the eleventh chamber in G. cretacea. R. rugosa. and C. pilula. The amount of change in slope after the inflection point also varies between species. The growth rates of all morphotypes of

Archaeoglobigerina and G. cretacea strongly decrease in the final two chambers, as shown by a near horizontal or negative slope in the logarithmic curves. On the other hand, the slopes for the last chambers of R. rugosa. C. pilula. and H. sliteri diminish, but continue in the positive direction, indicating a reduced but persistent chamber size increase.

Mean values of chamber-by-chamber cross-sectional areas are plotted in Figure 18 for all species examined in this study.

Interspecific differences are quite apparent on these plots, as well as in the plate illustrations of complete serial dissections.

Costellagerina pilula and H. sliteri have the smallest mean proloculus diameters and the slowest and most gradual rate of chamber size increase (PI. Ill, Figs. 4, 10, 13; PI. V, Fig. 13). The first seven chambers of R. rugosa have a gradual increase in size, but the rate changes at about the eighth chamber, which initiates a faster size

Increase (PI. IV, Figs. 6 , 13-15). This species also has the largest final chamber size (Fig. 18). The plot for A. mateola closely parallels that of &. australis through the initial ten chambers, but the slope for &. mateola changes to zero after about the eleventh chamber. This decrease in rate of chamber size increase is also apparent in the complete serial dissection illustrations for this species (Pi. I, Figs. 13-15). A similar decrease in slope is shown for A. bosouensis after the tenth chamber (Fig. 18). The initial rate 87

4.5 A. o u s t r a l u A. bosqumsis

G. c r c f u t a A. mataola. R. ruffosa

i _ C. pilula

H. s l t i r r i JB 3.5 -

(_>

2.5 -

0 2 4 6 8 10 12 14 16 Number of Chambers

Figure 18. Wean logarithmic values of the chamber-by-chamber increase in cross-sectional chamber areas of all Upper Cretaceous planktonic forarainifer species analyzed in this study. Changes in slope reflect ontogenetic changes in the rate of chamber size increase. Note the smaller value of the deuteroconch (#2 chamber) relative to the proloculus (#1 chamber), Data sets from measurement of adult specimens of Archaeoglobigerina australis n. sp. from DSDP Site 511 and ODP Site 690 were combined on this graph. See Figures 15-17 for standard deviations and number of specimen measurements of each species. 88

of chamber size increase for A. bosouensis is higher than that of

The largest prolocular and juvenile chamber sizes occur in £. cretacea. which has a decreased rate of size increase beginning at about the twelfth chamber (Fig. 11; Pi. I, Fig. 7).

SEM observations. Observations of the initial and penultimate whorl morphology reveal important interspecific differences in chamber morphology, surface ornamentation, and apertural shape and position.

"Hedbergellid" morphologies (axially compressed chambers, extra- umbilical apertures) were found in the initial whorls of all species examined (e.g., PI. Ill, Fig. 3; PI. VII, Fig. 12; PI. VIII, Figs. 7-

8 ; PI. IX, Fig. 15). The penultimate whorl chambers of 4- australis

(PI. IX, Figs. 3, 8), 4- bosquensis (PI. 10, Figs. 5, 11, 14), 4 . mateola (PI. I, Fig. 12), G. cretacea (PI. I, Fig. 5), and E- rugosa

(PI. IV, Figs. 5, 12) show "globigerine" morphologies (strongly inflated chambers, nearly umbilical apertures), whereas the penultimate whorls chambers of C. Pilula and H. sliteri still show compression in the axial direction (PI. Ill, Figs. 3, 8 ; PI. V, Fig.

16).

The size and density of surface pustules decreases in successively earlier chambers in all groups observed (e.g, PI. VIII, Figs. 3, 7-8,

10-12; PI. I, Figs. 9-12). Although secondary calcification has been observed on the surface of interior chambers in some modern species,

(Brummer et al., 1987), thin chamber walls in the penultimate whorl, revealed by serial dissections (e.g., PI. VIII, Fig. 8), indicate that secondary calcification has not overprinted interior chamber surface 89

ornament. However,, secondary calcification may explain the absence

of pores in several of the chambers in the initial whorl (PI. IV, Fig.

15; PI. V, Fig. 18; PI. VII, Figs. 6 , 10, 19; PI. IX, Fig. 16; PI. 10,

Fig. 9; PI. I, Fig. 8).

DISCUSSION

ONTOGENETIC STAGES

Brummer et al. (1987) demonstrated that changes in test

morphology, particularly test diameter, correspond to changes in vital

behavior during the ontogenetic development of modern specimens of

Globjgerinoides sacculifer (Brady) and Globigerinoides ruber

(d'Orbigny). Based particularly on changes in rates of test size

increase, they recognized five ontogenetic stages: prolocular,

juvenile, neanic, adult, and terminal stages. Transition from the

juvenile to neanic stage typically occurred in test diameters between

65 and 95 microns, and transition from neanic to the adult stage

occurred at a test diameter between 160 and 200 microns. The terminal

stage was recognized after initiation of the reproductive process.

Specimens of G. sacculifer produce one or two chambers of diverse

morphology during this final stage.

Three ontogenetic stages can be discerned from the logarithmic

curves and SEM micrographs of the Upper Cretaceous planktonic species, based on changes in the chamber-by-chamber growth rate and test morphology. These include the prolocular, juvenile, and adult stages

(Fig. 19). The prolocular stage comprises formation of the first chamber of the planktonic foraminifer test, which is always larger 90

Archaeoglobigerina azistralis DSDP Lag 511

2.8 -

0 2 4 8 8 10 12 14 Numbar of Chambers

Figure 19. Logarithmic plots of cross-sectional chamber areas measured from one juvenile and two adult specimens of Archaeoglobigerina australis n. sp. from Sample 71-511-24-5,69-71, Transition from the juvenile to adult stage for this species does not occur abruptly and may vary among different specimens. It is characterized by movement of the aperture from an extra-umbilical to umbilical position, decreasing axial test compression, and a decrease in the rate of chamber size increase. Note that the sequential chamber size is strongly controlled by the size of the prolocular (first) chamber. 91 than the deuteroconch and usually smaller than subsequent chambers.

The external prolocular wall Is smooth and lacks pores and surface ornament.

The juvenile stage includes sequential chambers that show a log- linear size increase. Apertural position is extra-umbilical or umbilical-extra-umbilical but never entirely umbilical, and apertural shape is typically a low, wide arch. Surface ornament of the juvenile chambers typically increases with successive chambers and is not as well developed as in the adult chambers. Some kummerform Juvenile species of A. australis (PI. VIII, Figs. 7-8) have pronounced axial compression in the early chambers of the Initial whorl.

Transition from the juvenile to adult stage (Fig. 19) may be gradual or abrupt and typically varies within different specimens of a species. Nevertheless, the mean chamber size and successive chamber number where this occurs in a species population appears to be taxonomlcally distinctive. This transition is characterized by a decrease in the rate of chamber size increase, relative to the previous chambers, and a change in apertural position from extra- umbilical to umbilical in globigerine species. For A. australis and

A. bosQUensis. this transition typically occurs after the ninth or tenth chamber, at a chamber cross-sectional area of 5,000-8,000 microns2 and test diameter of 180-220 microns. The juvenile-adult transition in &. mateola also generally occurs after the ninth chamber, at chamber areas of 4,000-7,000 microns2 and test diameters of

150-200 microns. Onset of the adult stage generally occurs after the twelfth chamber for G, cretacea. C. pilula. g. rugosa. and H. sliteri. 92

G. cretacea and g. rugosa vary widely in chamber areas (7,000-18,000

microns2) and test diameters (200-250 microns) after initiation of the

adult stage. This range is considerably lower for C, pilula (3,000-

9,000 microns2 area; 170-200 microns test diameter) and H. sliteri

(5,000-10,000 microns2 area; 150-180 microns test diameter).

A change in the number of chambers in the final whorl relative to

the previous whorls may also occur during transition to the adult

stage, depending on the amount of change in chamber size and the

height of the coiling axis. In addition, external features, such as

surface pustules, portici, tegilla, or peripheral keels, attain their

maximum development during the adult stage. Formation of kummerform

or aberrant final chambers on some specimens of australis (PI. II,

Figs. 5-8), bosquensls (PI, IX, Figs. 1-2, 10), and &. mateola (PI.

I , Fig. 9) also occurs during this stage.

PALEOENVIR0NMENTAL INFERENCES

An overlay of logarithmic plots of mean cross-sectional chamber

area for the three data sets of A. australis is shown in Fig. 20.

Note that the plots for the adult morphotypes from DSDP Leg 71 and ODP

Leg 113 compare quite closely throughout their ontogeny, whereas the

plot for the juvenile forms shows lower mean values, particularly for

the last two chambers measured. The substantial range of morphologic

variability displayed by juvenile and adult morphotypes of &.

australis (see Tables 1-2; Figs. 5-7; PI. VII-8), is responsible for considerable taxonomic confusion (see systematics section below). 93

Archaeoglobigerina australis 4.5 -i DSDP Log 71 (j) DSDP Leg 71 (a) ODP Log 113

j Q 3.5 -

2.5 -

0 24 6 8 1 0 12 14 Number of Chambers

Figure 20. Logarithmic plots of the mean cross-sectional chamber area of juvenile and adult specimens of ArchaeoglobiEerlna austral1 & n. sp. from DSDP Leg 71 and adult specimens from ODP Leg 113. Note that the Leg 71 and Leg 113 adult morphotypes compare closely in their mean values, but the mean values of the juvenile specimens diminishes particularly after the eighth chamber. 94

The range of morphologic variability shown by A. australis is paralleled by the late Neogene and modern species of NeoEloboquadri na pachvderroa (Ehrenberg), Globigerina bulloides d'Orbigny, and

Globigerlnoides sacculifer (Brady), Kennett (1968) recognized three latitudinal variants of N. pachvderma in surface sediments of the

South Pacific based on systematic changes in test size, shell thickness, number of chambers and dominant coiling direction.

Subsequent studies on N. pachvderma (Malmgren and Kennett, 1972;

Keller, 1978) and G. bulloides (Malmgren and Kennett, 1976, 1977) have correlated changes in morphology primarily to temperature-related phenomena, although some authors used differences in exterior morphology to classify distinct new species (Cifelli, 1961, 1973;

Olsson, 1974, 1976).

Phenotypic variants of living specimens of Globleerinoides sacculifer were produced by varying temperature and salinity conditions in laboratory cultures (Hemleben et al., 1987). These authors found that differences in external appearance were so strong that the morphovariants could not be distinguished at the species level from five other planktonic taxa. Laboratory culture studies of

G. sacculifer have demonstrated a strong interdependence of test size, chamber morphology, and total lifespan on several important physical and chemical parameters. Rapid onset of gametogenesis, resulting in premature termination of the parent cell and stunted shell growth, was induced by reduction in light intensity (B6 et al., 1981), longer feeding frequency (Caron et al., 1981) and lowered salinity and temperature (Hemleben et al., 1987). Kununerform chambers were most 95

frequently formed on smaller tests, but their occurrence was not

correlated with temperature or salinity conditions (Hemleben et al.,

1987).

These above morphologic studies of modern and late Neogene

globigerine species indicate that extreme changes in morphologies can

be correlated with extreme changes in environment. Therefore, the

widest range in morphologic variability in planktonic foraminifers can

be expected in the most seasonally extreme environments, such as the

polar regions. Perhaps the high degree of morphologic variability

demonstrated by Archaeoglobieerina australis is caused by its

habitation in an intensely seasonal high latitude environment.

Juvenile forms of this species, which frequently produce kummerform

chambers and show the most extreme ontogenetic morphometric

variability (Tables 1-2; Figs. 12, 13), may represent growth and

premature gametogenesis during periods of low light and nutrient

availability. The relative abundances of Juvenile and adult forms of

this species could be used as a paleoenvironmental tool to reveal

stratigraphic and areal differences in seasonal variability of the

Cretaceous polar regions.

Differences in mean proloculus size of the A. australis morphotypes (Figs, 19, 20) may be an indicator of surface water conditions during the Late Cretaceous. Sverdlove and (1985) hypothesized that maximum prolocular size in planktonic foraminifers

is attained in conditions of high temperatures, high nutrient availability and strong light intensity. They suggested that prolocular (and successive) chamber size diminishes with decreased 96

levels of these parameters. The lower mean proloculus diameters shown

for juvenile forms of A. australis (Fig, 20) may provide additional

evidence of their growth in a limiting environment.

TAXONOMIC NOTES

Formal systematic description of the new species Hedbergella

sliteri. Archaeoeloblgerina australis and Archaeoglobigerina mateola

are presented in the Systematic Description section of Chapter III,

The section below summarizes important distinguishing features for all

species analyzed, as revealed in exterior view and from ontogenetic

morphometric study, and discusses their taxonomic classification and

phylogenetic relationships, Synonomy lists are limited to type

designations and reported occurrences in high southern latitude

regions. Results of morphometric measurements for each species are

presented in Tables 1-2 and Figs. 5-11.

HEDBERGELLA SLITERI N. SP.

(PI. I. Figs. 1-5; PI. V, Figs. 11-18)

Globorotalia monmouthensis (Olsson), Webb, 1973b, p. 552, PI. 3, Figs.

1 - 2 .

Hedbergella holmdelensis Olsson, Sliter, 1977, p. 542, PI. 2, Figs. 1-

Hedbergella monmouthenesis (Olsson), Huber, 1988, p. 206, Fig. 27.14-

27.17.

Hedbergella sliteri n. sp., (see Chap. III).

Remarks. This species differs from H. holmdelensis and |J. 97 monmouthensis by its larger size, wider umbilicus, and by having a more gradual rate of chamber size increase in the final whorl. It has a shallower and broader umbilicus than H. monmouthens is and a more symmetric apertural face than H. holmdelensis. Topotype specimens of

H- holmdelensis and H. monmouthensis (PI. V, Figs. 1-3, 6 -8 ), recovered from a sample of the Maastrichtian Redbank Formation (New

Jersey), were too rare and infilled with pyrite for detailed ontogenetic morphometric comparison. An additional form of

Hedbergella. shown in PI. V, Figs. 4-5, 9-10, occurs in the Redbank

Formation sample, but it is too rare for morphometric analysis.

H. sliteri first appears in lower Maastrichtian sediments at ODP

Sites 689 and 690, co-occurring with H. holmdelensis and H- monmouthensis. and it ranges with H. monmouthensis through the upper

Maastrichtian (see Chap, III), H. monmouthens is first appears in upper Campanian sediments at the Falkland Plateau, whereas H- holmdelensis ranges into sediments of probable early Campanian age.

It is difficult to determine, based on external morphology alone, from which hedbergellid species H. sliteri evolved. Greater similarity in chamber symmetry and wall surface texture suggest a closer phyletic relationship with H. monmouthensis than with H. holmdelensis (Fig.

14). Ontogenetic morphometric analysis of the older hedbergellid species may reveal more distinguishing taxonomic features than are presently recognized.

COSTF.I.IAGERINA BULBOSA (BELFORD)

(PI. Ill, Figs. 1-13) 98

Rugoglobieerina bulbosa Belford, 1960, p. 94, PI. 26, Figs. 1-10,

text-fig. 7.

RueoelobigerIna pilula Belford, 1960, p. 92, PI. 25, Figs. 7-13, text- flg. 6 . Robaszynski et al., 1984, p. 285, 302.

Whitenella bulbosa (Belford), Belford, 1983, p. 2-3, PI. I, Figs. 1-

12, PI 2, Figs. 1-2. whitenella pilula (Belford), Belford, 1983, p. 2-3, PI. 2, Figs. 3-8,

PI. 3, Figs. 1-5.

Costellagerina bulbosa (Belford), Petters et al., 1983, p. 250, PI. I,

Figs. 1-14.

Remarks. The taxonomic classification of this species has undergone several revisions since Belford's (1960) original description of Santonian specimens from Western Australia. Belford

(1983) noted that the meridional pattern of ornamentation, defined as a primary generic character of Rugoglobleerina by Banner and Blow

(1959), was repeated several times during the Cretaceous. Although he also considered this ornamental feature to be of generic importance,

Belford (1983) proposed that the absence of tegilla and imperforate peripheral bands and the extra-umbilical tendency of apertures in specimens of R. bulbosa and R. pilula warranted their removal from

Rugoglobigerina. Belford placed these species in Whitenella. but indicated that the type description of that genus (Pessagno, 1967) made no reference to surface ornamentation of the test.

Petters et al. (1983) subsequently described a new genus,

Costellagerina. to accomodate the Belford's species, and they designated C, bulbosa as the type species. They placed C. bulbosa and i ti

cmt *

Figure 21. Figure 21. Phylogenetic reconstruction inferred for Upper Cretaceous planktonic foraminifer species discussed in this study based on results of ontogenetic comparisons. Rupotruncana cimimnodifer and Marginotruncana pseudolinneiana Pessagno were not analyzed in this study; the phylogenetic link inferred for Rugotruncana and Rueoglobigerina is from Robaszynski et al. (1984). Ontogenetic study of G. cretacea suggests an marginotruncanid ancestral stock, rather than ancestral relationship with Whitenella. as proposed by Pessagno (1967) and Robaszynski et al. (1984).

99 101

£. pilula in the family Rotaliporidae and subfamily Hedbergellinae

because of the extra-umbilical-umbilical aperture and portici that

extend over the aperture.

Robaszynski et al. (1984) placed Belford's meridionally costellate

species In Rugoglob leerina and synonomized the four chambered

morphotype (-E- bulbosa of Belford, 1960) under R. pilula. They

indicated that R. pilula may have been the ancestral stock from which

Campanian-Maastrichtian rugoglobigerinid species evolved.

Differences in ontogenetic morphology of C. pilula from the

interior morphology of R.. rueosa demonstrates that Petters et al.

(1983) were clearly justified in removing C. bulbosa and C. pilula

from Rugoglobigerina and designating a new genus. Dissection of the

test interior of this species reveals a hedbergellid morphology

occurring throughout ontogeny (Table 2; Pi. III). Meridionally

aligned costellae do not appear on chambers in the initial whorl and

show variability in external expression on chambers of the ultimate whorl. The rate of chamber size increase is more similar to H-

sliteri than any other species analyzed; a near log linear size

increase occurs throughout most of the ontogeny of £, pilula (Figs.

17, 18). Retention of adult morphologic characteristics similar to

species of Hedbergella suggests a close phylogenetic relationship with

the hedbergellid lineage (Fig. 21).

Similarity in the ontogenies of the four to five chambered morphotype, originally designated as R. bulbosa. and the five to six chambered morphotype, originally named R. pilula (PI. Ill, Figs. 1-

13), suggests that these forms are ecophenotypes of the same species. 102

£• Pilula Is here regarded as considered here as senior synonym of the

two species because of its wider usage in the literature. Both

xnorphotypes have the same reported stratigraphic range (Santonian-

early Campanian) and frequently occur at the same outcrop localities

(Belford, 1960).

ARCHAEOGLOBIGERINA AUSTRALIS N. SP.

(PI. I, Figs. 6-27; PI. II, Figs. 1-12; PI. VI, Figs. 8-11;

PI. VII, Figs. 1-19; PI. VIII, Figs. 1-8; PI. IX, Figs. 5-9, 11-

19)

Hedbergella monmouthensis (Olsson), Sliter, 1977, p. 542, PI. 3, Figs.

1-3. Krasheninnikov and Basov, 1983, p. 804-805, PI. 6 , Figs. 5-8.

Rugoglobiperina pilula Belford, Sliter, 1977, p. 542, Pi. 10, Figs. 7-

9. Krasheninnikov and Basov, 1983, p. 807, PI. 1, Figs. 3-6.

Rugoglobleerina pustulata BrOnnimann, Krasheninnikov and Basov, 1983,

p. 806, PI. 10, Figs. 10-13.

Rugoglobigerina rotundata BrOnnimann, Sliter, 1977, p. 543, PI. 1,

Figs. 1-3. Krasheninnikov and Basov, 1983, p. 807, PI. 1, Figs. 7-11.

Huber, 1988, p. 206, Figs. 28.12-14.

Archaeoglobjgerina australis n. sp., (see Chap. III).

Remarks. The "typical" initial whorl morphology of £. australis

is demonstrated by adult normalform specimens from both the Falkland

Plateau and the Maud Rise (Pi. IX, Figs. 5-9, 11-19). The chambers have a rate of size increase that is rapid in the initial and penultimate whorls, then a more gradual size increase in the ultimate whorl. Seymour Island specimens included in this species have 103

identical exterior and interior morphologies to the normalform adult

specimens from the Falkland Plateau and Maud Rise.

More extreme variability occurs in the interiors of some

normalform juvenile (Pi. VII, Figs. 7-8, 11-19) and kummerform

juvenile (PI. VIII, Figs. 1-8) specimens. These have a wide range of

prolocular and initial whorl diameters, rate of chamber size increase,

and the number of chambers in both the initial and ultimate whorls.

As discussed above, the variability in these forms is considered to be

caused by ecophenotypic rather than genetic differences. More

detailed ontogenetic analysis of kummerform and juvenile populations

should be completed to confirm this, however. Surface ornamentation

on £. australis generally consists of fine to coarse pustules that are

randomly situated on the entire test surface. Portici are usually present, but no true tegilla have been identified.

Morphometric data (Tables 1, 2) and SEM illustrations (Plates IX,

X) demonstrate that adult A. australis specimens are very similar in ontogenetic morphology to specimens of A. bosauensis. Mean values of proloculus and initial whorl diameters, as well as number of initial whorl and penultimate whorl chambers, are nearly the same for both species. In fact, some A. australis specimens (e.g., PI. IX, Figs.

11-12) also appear Identical to specimens of A. bosauensis in external morphology. Populations of the two species differ primarily in the chamber arrangement of the final whorl, where A. bosauensis is more tightly coiled and higher spired and frequently has final chambers covering part or all of the umbilical region.

australis and bosauensis are separated by a considerable 104

span of geologic time. A. bosquensis has only been reported in

Coniacian-Santonian sediments, whereas A. australis first appears in

the middle Campanian of Falkland Plateaus DSDP Site 511 (pers. obs.).

Ontogenetic similarities of these two taxa indicates that A- bosauensis is probably the ancestral species from which A- australis was derived (Fig. 21). Perhaps further study of Campanian deep sea

sediments will reveal overlapping ranges of these species.

Inclusion of A- austral is. A. mateola. and A. bosauensis in

Archaeoglobieerina differs from the original description of that genus, which suggests that tegilla should be present in well preserved specimens (Pessagno, 1967, p. 315). Furthermore, the type species of this genus, A. blowi Pessagno, often bears an imperforate peripheral band occasionally aligned with two faint rows of pustules, whereas neither specimens of A. australis nor A* bosauensis bear faint suggestion of these features. Examination of topotype specimens of A. blowi revealed test infilling and insufficient preservation for ontogenetic comparison. A more definite determination of the taxonomic status of A. australis and A. bosauensis must await detailed study of better preserved specimens of A. blowi.

Two specimens have final whorl chamber arrangements that are very similar to A. mateola. but have a pustulose surface ornamentation similar to A* australis. The "bimodal" prolocular and initial whorl diameters of these forms (Fig. 12; PI. VIII, Figs. 9-17) suggests closer affinity to A- mateola. 105

ARCHAEOGLOBIGERINA CF. A. AUSTRAl.IS N. SP.

(PI. VI, Figs. 1-7, 12; PI. IX, Figs. 1-4, 10)

Rugoglobizerina rugosa (Plummer), Huber, 1988, p. 207, Figs. 28.1-11.

Remarks. Rare specimens from the Falkland Plateau and Seymour

Island have faint meridional alignment of pustules and apertural cover plates resembling a tegillum (PI. VI, Fig. 1; PI. IX, Figs. 1, 4).

Serial dissection of the Seymour Island and Falkland Plateau specimens reveals ontogenetic morphologies identical to randomly ornamented specimens of £. australis but have no resemblance to Rugoelobigerina. indicating possible parallel evolutionary development of this external ornamental feature. These forms were too rare at both localities for detailed morphometric study. Until more specimens of these meridionally costellate morphotypes are analyzed, they are tentatively classified with australis. but a possible evolutionary splitting during the late Campanian is postulated (Fig. 21).

ARCHAEOGLOBIGERINA BOSQUENSIS PESSAGNO

(PI. X, Figs. 1-16)

Archaeogloblgerlna bosquensis Pessagno, 1967, p. 316, PI. 60, Figs. 7-

12. Sliter, 1077, PI. 9, Figs. 3-5. Krasheninnikov and Basov, 1983, p.

805-806, PI. 8 , Figs. 1-8.

Remarks. Similarity of A. bosquensis to A. australis and their inferred close phylogenetic relationship (Fig. 14) was discussed above. The Gulf Coast holotype and paratypes of A. bosouensis are much more poorly preserved than Falkland Plateau specimens Included in this species, as their tests are completely infilled with silica. 106

Some Falkland Plateau forms differ from the type specimens by having a higher coiling axis and more tightly coiled chambers. The greater range of morphologic variability exhibited by the Falkland Plateau specimens may be related to their high latitude environment, as was suggested above to explain the highly variable morphologies of &. australis.

ARCHAEOGLOBIGERINA MATEOLA N. SP.

(PI. VIII, Figs. 9-17; Figs. 9-17; Pi. I, Figs. 9-16)

Rugoglobiperina sp. 2 Huber, 1988, p. 207, Figs. 31.12, 31.15-16.

Archaeoglobigerina mateola n . sp., (see Chap. III).

Remarks. This species is characterized by having very coarse pustules that sometimes protrude as spines, a high breadth/diameter ratio, and a high frequency of kummerform or aberrant final chambers.

Mean prolocular and initial whorl diameters are larger and have a greater range of variability in A. mateola than was found in australis. Extreme differences in prolocular diameter were exhibited in several specimens (PI. VIII, Figs. 9-17; PI. I, Fig. 14), and blmodalilty in plots of proloculus and initial whorl diameters was previouly noted (Fig. 12). Some forms included in this species strongly resemble specimens of A. bosquensis (e.g., PI. VIII, Fig. 9) and australis (e.g., PI. VIII, Figs. 13-14) in external view, but have marked differences from those species in their initial whorl morphology (PI. VIII, Figs. 16-17). Similarity in the initial and penultimate whorl morphology of most specimens of mateola (e.g.,

PI. VIII, Fig. 11; PI. I, Figs. 15, 16) to A. austral!s and &. 107 bosquensis suggests their close phylogenetic relationship (Fig. 14).

The oldest occurrence of A. mateola is uncertain, as this species was found in the oldest sediments recovered at ODP Site 690 (see Chap.

Ill) but was not found at the Falkland Plateau. It is inferred to have evolved from A. australis during the upper Campanian.

GLOBOTRUNCANA CRETACEA (D'ORBIGNY)

(PI. XI, Figs. 1-8)

Globlgerina cretacea d'Orbigny, 1840, p. 34, PI. 3, Figs. 12-14.

Archaeogloblgerina cretacea (d'Orbigny), Pessagno, 1967, p. 317, PI.

70, Figs, 3-8, Pi. 94, Figs. 4-5. Robaszynsky et al., 1984, p. 278,

PI. 47, Figs 3-6, PI. 48, Fig. 2.

Globotruncana cretacea (d'Orbigny), Krasheninnikov and Basov, 1983, p.

806, PI. 8 , Figs. 13-15.

Remarks. The large mean values obtained from measurement of the prolocular and initial whorl diameters in G. cretacea clearly demonstrates that this species shares no ontogenetic similarity to the other species analyzed. The reniforra penultimate and ultimate whorl chamber morphology, low test breadth/diameter ratio, and presence of an imperforate peripheral band suggests this species was derived from an ancestral marginotruncanid stock and not from the genus Whitenella. as was proposed by Pessagno (1967) and Robaszynski et al. (1984).

Measurement of the initial whorl chambers in other globotruncanid species should be done to reveal whether they have similarly large dimensions. 108

RUGOGLQBIGERTNA RUGOSA (PLUMMERS

(PI. V, Figs. 1-15; PI. VIII, Figs. 1-7)

Globigerina rueosa Plummer, 1927, p. 38, PI. 2, Fig. 10.

Rugoglobigerlna rugosa (Plummer), Webb, 1973b, p. 552, PI. 3, Fig. 3-

8 .

Remarks. Gulf Coast specimens of R. rugosa from the upper

Maastrichtian Kemp Clay, where this species was originally described, were studied for comparison with specimens that occur in very rare abundance in upper Campanian-Maastrichtian sediments on Seymour

Island. Huber (1988) noted that some Seymour Island specimens have umbilical tegllla and faint meridional alignment of pustules, but no specimens were found bearing well developed meridionally aligned costellae typical of low latitude forms of Rueoglobigerina. The few

Seymour Island specimens subjected to the serial dissection needle were victims of an inexperienced operating staff; only one measurement of initial whorl chamber dimensions was successfully obtained.

Nevertheless, complete dissection of faintly meridionally costellate specimens from Seymour Island (PI. VI, Figs. 12) and the Falkland

Plateau (PI. IX, Figs. 1-4, 19) reveals interior morphologies identical to forms included in A. australis. but unlike that of dissected topotype specimens of R. rueosa (PI. V, Figs. 6 , 13-16).

Therefore, the Antarctic and Falkland Plateau forms are presently designated as cf. A. australis.

The most distinguishing ontogenetic morphometric parameters of the

Gulf Coast morphotypes include the rate of chamber area increase and number of chambers in the initial whorl. These chambers show a very 109 gradual Increase In size, enabling a relatively large mean number

(5.42) to occur. The chamber size increases much more rapidly in the penultimate whorl and growth remains nearly log linear until the penultimate or ultimate chamber (Fig. 17). The initial whorl chambers are more reniform in cross-sectional view than specimens included in

Archaeoglobigerina and final whorl chamber sizes are larger for £. rueosa than for any other species measured.

Other high southern latitude occurrences of R. rugosa were reported from New Zealand (Webb, 1971) and DSDP Site 208 in the Tasman

Sea (Webb, 1973b). This species has not been found in deep sea sediments from the southern South Atlantic, however. The New Zealand forms and most of the Site 208 specimens have a considerably reduced density of meridionally aligned costellae and a more random orientation of surface pustules, as occurs with specimens designated in this study as A. cf. A. australis. The contrasts in low versus high latitude external morphologies of specimens included in £. rueosa suggests that there was a latitudinally differentiated morphologic cline that may have been genetically controlled. On the other hand, the high latitude mophotypes may all be descendants of the australis lineage (Fig. 21). Designation of a new high latitude species or subspecies is not warranted until more complete biogeographic and morphometric information is obtained for the mid to high latitude meridionally costellate forms of this species.

CONCLUSIONS

Ontogenetic morphometric characterization of individual species 110 populations enables a quantitative determination of the range of morphologic variability in a wide array of measurable parameters.

This leads to a more concise definition of species concepts and enables development of a more "natural" classification scheme, as well as a more reliable basis for reconstruction of phylogenetic histories.

Moreover, there is great potential for application of comparative ontogeny in biostratigraphy. Using this method to precisely define lineage zones may be particularly useful for improving biostratigraphic resolution in high latitude regions, where biostratigraphic datum events are usually widely separated in geologic time.

Although shape analysis of test exteriors has been successfully applied to several Cenozoic planktonic lineages (e.g., Malmgren and

Kennett, 1981, 1983; Healy-Williams and Williams, 1981), this method could not be used with Upper Cretaceous globular trochospiral foraminifers from the extra-tropical southern latitudes because of their highly variable morphologies. Ontogenetic morphometric comparison of Archaeoglobigerina australis n. sp. with topotype specimens of Costellagerina pilula and Hedbergella monmouthensis. in which australis was previously classified, clearly reveals very little similarity in their developmental morphology. Comparison of A. australis with Globotruncana cretacea. which has been frequently assigned to the genus Archaeoglobigerina. and Rueoglobigerlna rugosa also discloses little similarity. Much closer affinity is inferred between £. australis. Archaeoglobigerina mateola n. sp., and

Archaeoglobigerina bosauensis Pessagno based on the test interior I l l observations. More work is needed, however, before a hierarchial ordering of test Interior taxonomic characters can be established in classification schemes for Upper Cretaceous planktonic foraminifers.

Comparative ontogeny of species also enables recognition of pre adult growth stages, affording identification of juvenile forms deposited in unstable depositional environments where adult specimens may be rare. This approach was effectively used in this study to identify immature and aberrent forms of A, australis recovered from upper Campanian-Maastrichtian nearshore marine sediments on Seymour

Island (Antarctic Peninsula). Recognizing that growth morphologies of modern planktonic foraminifers are strongly affected by the ambient surface water environment in which they grow (e.g., Be et al., 1981;

Caron et al., 1981; Hemleben et al., 1987) suggests potential application of the ontogenetic morphometric approach for characterizing ancient surface water environments. Plate V. Serial dissections and x-radiographs of species of Hedbergella. Figs. 1-3. Hedbergella holmdelensis Olsson, Redbank Formation, sample NJK-3, New Jersey (210 pm) . Figs, 4-5, 9-10. Hedbergella sp., Redbank Formation, sample NJK-3, New Jersey (214 pm). Figs. 6 -8 , Hedbergella monmouthens is (Olsson), topotype from Redbank Formation, sample NJK-3 (170 pm). Figs. 11-18. external and internal views of Hedbergella sliteri n. sp., DSDP Site 327, Falkland Plateau. 11-13, 15: 236pm. 14: 282 pm, 16-17: 249 pm. 18: width of photo is 234 pm.

112 113 Plate V

O LT

3 Plate VI. Specimens of Archaeoglobigerina cf. A. austral!s n. sp. from lower Maastrichtian sediments on Seymour Island (Antarctic Peninsula). Figs. 1-7, 12. External and microradiograph views and serial dissections of a single specimen from sample 165. Note the similarity in external view to Rueq globieerina rugosa. with the presence of meridionally aligned pustules on the penultimate chamber and an umbilical tegillum. Complete serial dissection of this specimen reveals an initial whorl morphology with little resemblence to £• rugosa. but Identical morphology to randomly ornamented specimens of A- australis from the Maud Rise and Falkland Plateau. The initial whorl chambers in the Seymour Island specimen are more globular and increase more rapidly in size than the initial whorl chambers of R. rugosa (301 fim). Figs. 8-11. External, microradiograph views of a juvenile form of A. australis n. sp. , from sample 415 (208 ftm) .

114 115 Plate VI Plate VII. Juvenile forms of Archaeoglobigerina australis n. sp. from sample 71-511-24-5,69-71, Falkland Plateau. Note variability in the prolocular and initial whorl dimensions and the number of chambers occurring in the initial whorl. Figs. 1-6. External and x-radiograph views and serial dissections (178 pm). Figs. 7-8. External view and complete dissection (170 pm). Figs. 9-10. Complete dissection and ★enlarged view of the initial whorl (181 pm). Figs. 11-13. External view and serial dissections (199 pm). Figs. 14-15. External view and complete dissection (202 pm). Figs. 16-19. Microradiograph and serial dissections (197 pm).

116 Plate VII Plate VIII. Figs. 1-8. Kummerform juvenile specimens of Archaeoclobigerina australis n. sp. showing a higher number of initial whorl chambers than adult forms. 1-4, 7-8. Exterior and microradiograph views and serial dissections, Sample 71-511-23-4,67- 69. Note the transition from a globigerine morphology in the penultimate whorl to a more axially compressed hedbergellid morphology in the initial whorl (265 /an), 5-6. Exterior view and complete dissection, Sample 71-511-23-4,67-69 (170 /im). Figs. 9-17. Kummerform specimens designated as &. mateola n. sp. lacking the strong spinosity typical of this species, but having similar internal morphologies. 9- 12, 17. Exterior view and serial dissections. Sample 113-689B-28-3, 83-87 cm. Note the globigerine penultimate whorl morphology and very large proloculus (253 ^m). 13-16. Note that this specimen has a very small proloculus (12 /im) and the test consists of more than three whorls (376 .

118 Plate VIII Plate IX. Adult specimens of Archaeoplobieerina cf. &. australis n. sp. and Archaeoelobigerina australis n. sp. Figs. 1-4, 10. Archaeoglobigerina cf. A. australis n. sp,, Sample 71-511-24-5,69-71 (252 pm). External view, microradiograph, and serial dissection of a specimen bearing faintly developed meridional costellae and a weak umbilical teglllum. The specimen was damaged during removal of the initial whorl chambers. Note the similarity in external features to cf. &. australis from Seymour Island (PI. VI, Figs. 1-7, 12). Figs. 5-9. External views and complete serial dissections of a specimen from Falkland Plateau Sample 71-511-24-5,69-71 showing a broad portical flap (316 ftm). Figs. 11-13. External views and complete dissection Maud Rise specimen from Sample 113-690C-19X-3,119-123 (230 /an). Figs. 14-17. Complete dissections of several specimens from the Maud Rise (Sample 113-690C-20X-3,116-118) showing consistent similarity in their initial whorl morphologies. 14: 262 pan. 15: 253 pm. 16: Width of photo - 141 pm. 17: 310 /an. Figs. 18-19. External view and complete serial dissection of Falkland Plateau specimen from Sample 71-511-24- 5,69-71 (362 Mm).

120 121 Plate IX Plate X. Santonlan specimens of Archaeoglobieerina bosouensis Pessagno from Falkland Plateau Sample 71-511-42-5,27-29. Figs. 1-5. Exterior views, micrograph, and serial dissection of a kummerform adult specimen (355 pm) . Figs. 6-7. Exterior view and complete dissection of a juvenile specimen (273 /im) . Fig. 8 . Complete dissection of an adult specimen (288 pm). Fig. 9. Enlarged view of an adult specimen showing the initial whorl morphology (width of photo - 75 pm). Figs. 10-15. External view and serial dissections of an adult specimen. Note the globigerine morphology of the penultimate whorl showing an umbilical-extra-umbilical aperture and more axially compressed, hedbergellid morphology of the initial whorl showing an extra-umbilical aperture and smooth outer chamber walls (325 pm). Fig. 16. Complete dissection of an adult specimen (292 pm).

122 123 Plate X Plate XI. Figs. 1-8. External and micrograph views and serial dissections of a single specimen of Globotruncana cretacea (d'Orbigny) from Campanian Sample 71-511-34-4,1-3. Note the reniform chamber morphology that appears in the initial whorl and continues throughout the ontogeny (424 pm). Figs. 9-16. Specimens of Archaeoelobigerina mateola n. sp. from upper Maastrichtian Sample 113-690C-18X-2,119-123. 9-12: External views of specimen with an aberrant final chamber and view showing dissected ultimate whorl. Note the smooth surface of the penultimate whorl chambers (280 pm). 13, 16: Serial dissection of a strongly spinose specimen revealing penultimate whorl chamber and initial whorl mophology (306 pm). 14: Complete dissection of a specimen with a large (28 pm) prolocular chamber. 15: Complete dissection showing initial whorl morphology (278 pm).

124 125 Plate XI CHAPTER I I I

MAESTRICHTIAN PLANKTONIC FORAMINIFERS FROM THE MAUD RISE

(SOUTHERN SOUTH ATLANTIC), OCEAN DRILLING PROGRAM LEG 113

ABSTRACT

An excellently preserved Maestrichtian planktonlc foraminifer fauna was recovered from ODP Leg 113 Holes 689B and 690C on the Maud

Rise (southern South Atlantic). Total diversity is 22 species, with dominance by species of Heterohelix. Globigerlnelloides. and

Hedbergella. Foraminifers endemic to the Austral Province are recognized for the first time, including Archaeoglobiperina australis n. sp., which dominates the polar assemblages, Hedbergella sliterl n. sp., and Archaeoglobigerina mateola n. sp. The former two species were previously illustrated in reports on Upper Cretaceous foraminifers from the Falkland Plateau and the northern Antarctic

Peninsula.

Three zones are proposed for correlation of high southern latitude sites, including the Globiperinelloides impensus Zone (upper

Campanian-lower Campanian), Globotruncanella havanensis Zone (lower to middle Maestrichtian), and Abathomphalus mavaroensis Zone (upper

Maestrichtian). The G. impensus Zone and lower G. havanensis Zone are correlated intervals in cores recovered from Falkland Plateau DSDP

126 127

Sites 327 and 511, but the upper G. havanensis Zone and all of the &.

mavaroensis Zone were not recovered from the Falkland Plateau.

A significant migration of keeled planktonic foraminifers to the

south polar regions is recognized at the Maud Rise. This occurs in

the upper G. havanensis Zone and continues through the &, mavaroensis

Zone. Two models are proposed to explain this event: 1) warming in

the polar regions and poleward expansion of the subtropical

Transitional Province, beginning in the middle Maestrichtian and

lasting through the late Maestrichtian; 2) polar surface waters

changed from being highly convective to vertically stratified through

the same time interval, enabling incursion of deeper dwelling

planktonic foraminifers.

INTRODUCTION

Maestrichtian foraminifers were recovered from Holes 689B

(64°31'S, 03°06* E) and 690C (65°10'S, 1°12'E) on the Maud Rise

(southern South Atlantic Ocean) during Ocean Drilling Program Leg 113

(Fig. 22). These well preserved assemblages are of particular

significance because they represent the southernmost Cretaceous

foraminifers recovered from deep sea sediments, providing valuable

information for high southern latitude biostratigraphic and paleobiogeographic reconstructions. In addition, the Maud Rise

sequence fills an important stratigraphic gap in the southern South

Atlantic region, because upper Maestrichtian sediments were not

recovered at DSDP Sites 327 and 511 on the Falkland Plateau (51°S), which were the southernmost Cretaceous deep sea sites prior to Leg 128

3 0 * S

40*S

511 EARLY MAESTRICHTIAN PALEOQEOGRAPHY JRI ,689 6 9 0

®o*s

Figure 22. Paleogeographic map for the early Maestrichtian showing the regional setting of Maud Rise Sites 689 and 690 and DSDP Sites 327 and 511. JRI refers to the James Ross Island region of Antarctic Peninsula. Small dots represent other DSDP and ODP sites drilled in the South Atlantic. Paleogeographic reconstruction after Barron (1987). 129

113. The nearest other occurrence of Upper Cretaceous foraminifers in

the high southern latitudes is from the James Ross Island region

(64°S) in the northern Antarctic Peninsula (Fig. 22). The faunal

distributions in that sequence were probably influenced by nearshore

depositional processes, however, and they are not considered useful

for extra-basinal correlation (Huber, 1988).

Uncertainties in cross-latitudinal correlation have inhibited previous efforts to accurately portray high southern latitude paleoceanic and paleoclimatic evolution during the Late Cretaceous.

Factors that have caused poor biostratigraphic accuracy in this region

include: 1) absence of thermophilic planktonic foraminifers used in

low latitude zonations, 2) low species diversity and equitability, with dominance by long-ranging, eurytopic taxa, 3) paleoenvironmental

influence on faunal distributions, causing diachronous first and last occurrences of some species, 4) provincialism and morphologic variability of several planktonic species, causing uncertainties in phyletlc relationships and taxonomic concepts, and 5) limited stratigraphlc and areal distribution of circum-polar sites yielding

Cretaceous sediments. In spite of these difficulties, several key marker species, previously not found in the south polar regions, occur at the Maud Rise. By correlating the Maud Rise foraminifers with calcareous nannoplankton distributions (Pospichal and Wise, in prep.) and the geomagnetic reversal stratigraphy (Hamilton, in prep,), a more precise biostratigraphic framework can be developed to emerge for the late Campanian-Maestrichtian time period. Thus, the paleoceanographic 130

and paleoclimatic history of this region can be reconstructed more

accurately than has hitherto been possible.

METHOD OF STUDY

Core-catcher samples and one sample per section were obtained from

the Cretaceous sequences recovered at Holes 689B and 690C. These were

disaggregated in warm water, ultrasonically cleaned, and seived

through a 63 micron screen. The dried residues were seived through a

150 micron screen and relative species abundances for 300 specimens

were counted in both the >150 micron and <150 micron fractions of each

sample (Appendices A-D). Foraminifers occurred in sufficient

abundance for complete counts of all samples studied.

Planktonic/benthic ratios and relative abundances were calculated from

the count totals.

Relative abundance rankings are as follows: abundant - 26-100%,

common - 16-25%, few - 6-15%, rare - 2-5% and very rare - <1%.

Species that were questionably present in samples were not included in

counts of species diversity.

Preservation of the Cretaceous foraminifers ranges from moderate

to excellent. Specimens distinguished as having moderate preservation

are fragmented and strongly etched or overgrown with secondary

calcite. Samples with good preservation yield mostly whole

foraminifer tests showing minor evidence of dissolution or secondary calcite overgrowth. Foraminifers whose preservation was judged as excellent show no evidence of diagenetic alteration in transmitted

light and their test walls are optically transluscent. 131

Core sample notation follows the standard ODP format, listing the

leg number, hole designation, core number and coring method, section number, and the centimeter interval within the section.

FORAMINIFER BIOSTRATIGRAPHY

HOLE 689B

A 64,6 m thick sequence of Maestrichtian chalk was recovered from

Hole 689B, situated at the crest of the Maud Rise 2,084 m below sea level in the southeastern South Atlantic Ocean (Fig. 22). The uppermost 3.9 m of the sequence, from 232.4 meters below sea floor

(mbsf) to 236.3 mbsf, are included in lithologic Subunit Ilia (Fig.

23), which is composed of moderately bloturbated, white nannofossil and foraminifer ooze with some finely dispersed ash interbeds. The remainder of the Maestrichtian sequence comprises Subunit Illb. This portion is more indurated than Subunit Ilia and is composed of moderately to strongly bioturbated, white to grey nannofossil chalk and foraminifer nannofossil chalk. Thin chert beds dispersed throughout Subunit Illb caused poor drilling recovery (33%) and eventual abandonment of this hole. The Cretaceous-Tertiary boundary interval was recovered just above Core 113-689B-26X, between 84 and 85 cm in Section -25X-5. It is discussed in detail elsewhere (Pospichal and Wise, in prep.; Stott and Kennett, in prep.).

The Cretaceous samples at Hole 689B all yield abundant foraminifers whose preservation ranges from excellent, typically In the middle of the section, to good in all but the lowermost sample, Figure 23. Summary of the drilling recovery, lithology, planktonic/benthic ratios, and planktonic foraminifer species diversity graphs for samples analyzed from the Cretaceous sequence of Hole 689B. These were taxonomically differentiated by family using the classification of Loeblich and Tappan (1988). Samples above Core 119-689B-27X were unavailable for this study.

132 133

* hole W% 1 : ! IS FORAMINIFERS 0 c o «* • _ Plank tonic Spoctas Wvofalty (*) i 1 » °s i* J10 12 I 14 I 16 I. _l28 50 I 75 L.

2 4 0 .

2*8 +T+ tr-u

i n i , •

2 8 0 ■f-*u JB*

288- M-l, •7 , CC< ■

*-r+ INI »-«t. 2 8 0 . »-< ININ

2 8 8 - tfl. 0C - ft-1, INI IMT'

2 7 0

2 7 8 n . c « +~+ I 280

2 8 8 • m

2 8 0 *

m , ee. 2 8 8 I *«■«

ForimMIirfta m FofwHlif mw i*< NiimofoiiN ehlli Chert

Figure 23. Figure 24. Distribution and relative abundance of upper Campanian through Maestrichtian planktonic foraminifers from Hole 689B, The plots are based on combined totals for 300 specimen counts of the >150 micron and <150 micron size fractions (Appendices A-B). Relative abundance rankings and planktonic foraminifer zones are shown at the bottom of the figure.

134 135

3 0 i- 3 0 (V • C 0 '4 01 .4 <4 <* -.4 t C 3 a 0 M ‘■4 k ■Q tu 14 0 0 0 0 0 (ft 0 0 TJ 0 k k C 0 •4 a k C k» c ■-* 3 -4 0 ♦- V 4- -4 0 0 V 0 V '4 &O •4 0 o 0 a 0 c 0 4- «- 3 c TJ 3 PI T1 c X 3 a 3 c 0 3 0 m Pi m 0 0 o 0 0 0 3 0 •4 6 0 £ 0 0 C s 0 3 0 c i. 4- E O 0 #4 +- c 0 0 •4 * '4 o e 0 k <_ 0 4 0 0 0 3 4 #4 k a +- k 0 tm. f- t- 4- o O 0* k 4 •4 0 0 k k k O 0 'P. 0 0 X i- o O 0 X X •4 0 £ £ £ XX 0 0 0 0 X X £ X 8 0 x £ X +- 4“ X Wl U o o *0 T3 4“ 4- 4» X o 0 O u 0 OI o O 0 It 0 0 X k *4 0 0 0 0 0 0 k H 4 0 3 3 4* X X e* 3 a o I XX X X (A X to 13 X 13 QC a a o a a U o ISS2S4x s as s a a s ESSt S :s s s sr at S* 3 St s :s s =s:= == *:= = :s s s s s a s s s t s

2 7 -iras-as 27-2,83-07 8 I 27-3,03-87 27, CC : 28-1,76-80 28-2,80-84 28-3,83-87 I 28-4, 83-87 H; O 28, CC E 28-1,83-87 H CO 28-2,83-87 UI 28-3,83-87 < 28, CC 30-1,83-85 30-2,88-82 30-3,78-83 30, CC 32-1,41-43 < 32, CC o 33, CC i I Very Rare (0-1 Percent) Rare (2-5 Percent) 1 - Abathomphalus mayaroensis Zone Few (6-15 Percent) Common (16-25 Percent) 2 = Globotruncanella havanensis Zone Abundant (26-100 Percent) Not Present 3 » Globigennelbkies impensus Zone

Figure 24. 136

which was rated as moderately preserved (Fig. 23). Planktonic/benthic

ratios are lowest at the base of the sequence (33% in Sample 113-689B-

33X,CC), and range between 6% and 25% above that level. Total planktonic species diversity is low throughout the studied interval compared with coeval assemblages from lower latitudes, with fewer than

11 species in the lower through middle Maestrichtian interval, and up

to 15 species in the upper Maestrichtian (Fig. 23).

Assemblages throughout the sequence are dominated by

Globieerinelloldes multisoinatus. Heterohelix spp., and a new species designated as ArchaeoglobiEerina australis (Fig. 24; Appendices A, B).

Globigerinelloides impensus. which was previously known only from upper Campanian sediments at the FalkLand Plateau (Sliter, 1977;

Krasheninnikov and Basov, 1983), comprises a significant proportion of the assemblages in the lowermost part of the sequence. This species was not present above Section 113-689B-32X-1. Hedbergella holmdelensls occurs only in Sample 113-689C-33X,CC, whereas monmouthensis is present in all Hole 689B samples. A distinctive new species, Archaeoelobigerina mateola. ranges through most of the sequence, with very rare to common abundance. Specimens of

Globotruncane11a havanensis and the new species Hedbergella sliteri both appear in Section 113-698B-30X-1 and range through Core 113-689B-

27X. The Maestrichtian species Globotruneane11a petaloidea and

Globleerinelloides subcarinatus first occur in Samples 113-689B-28X-

3,83-87 and -28X-1,76-80 respectively.

The most pronounced assemblage change in this section occurs with the appearance of the double keeled planktonic species Rueotruncana 137

circumnodlfer in Sample 113-689B-29X-2,83-87 (267.5 mbsf) and first

occurrences of G 1ob o t rune ana area and £. subcircumnnrii far in Sample

113-689B-28X,CC (265 mbsf). The diversity of double keeled taxa

Increases with the appearance of the upper Maestrichtian marker

species Abathomphalus intermedius and A. mavaroensis (Fig. 23;

Appendix A). The former species ranges from Section 113-689B-28X-2

through -28X-1, whereas A. mavaroensis occurs from Section 113-689B-

28X-1 through the top of the Cretaceous sequence. A decline in planktonic species diversity above Sample 119-689B-27X,83-87 (Fig.

23), corresponds with an increase in the relative abundance of benthic

taxa.

HOLE 690C

Hole 690C is located on the southwestern flank of the Maud Rise,

116 km southwest of Site 689 (Fig. 22) in 2920 m water depth. Cores

113-690C-16X through -22X penetrated 69.2 m of Maestrichtian chalk

that differs from material recovered at Hole 689B by its higher terrigenous component of fine-grained quartz, clay, and mica.

Drilling recovery averaged 66% for this sequence. The

Cretaceous/Tertiary boundary was determined to occur just above Core

113-690C-16X, between 68 and 50 cm in Section 113-690C-15X-4 and is discussed elswhere (Pospichal and Wise, in prep.; Stott and Kennett,

in prep.).

Two lithologic units are shown differentiated in the Cretaceous

sequence based on the relative amounts of nannofossil and terrigenous components (Fig. 25). Subunit IVc (252.5-281.1 mbsf) contains a Figure 25. Summary of the drilling recovery, lithology, planktonic/benthic ratios, and planktonic foraminifer species diversity graphs for samples analyzed from the Cretaceous sequence of Hole 690C. These were taxonomically differentiated by family using the classification of Loeblich and Tappan (1988). Samples above the core-catcher of Core 119-690C-16X were unavailable for this study.

138 139 o h m AGE UnH Zon* M u b#ptti (m) b#ptti I I I ChrDO C»OW C»OW 1 1 1 1 1 t! 1 t! 1 1 1 1 1 1 |-H~i |-H~i 1 1 m*)t C31W IV c IV i*t* 1 M if 1 M if 1 1 1 f i M 1 i f 1 bitM m ptiln .3 1 ! M1 ! 1 ? ? T 2 i is i 2 t 1 n it 1 = it 1 o n iJ j f i n 1 n i f j iJ 1 1 1 . _ - im

1 H1 h 1 MAESTNICHIAN 1 frbf 1 frbf 1 iiiis 1 1 1 1M1 1 1 1 1 1 U l M I * ? f t A f T T T ? A T rfrt i h I) I) h i rfrt 1 1 1 1 1 1 1 1 n h hh h h m i h b h «h anm bh hhh hn bh h i n h

1 )i )i 1 1 h airly n h h n

BltliotrMCMiHi h 1 trM 1 trM 1 1 c«n 1 1 H I t fit ( sSilssi si # i 5 8 i i i i 8 5 i # si sSilssi 1 1 J* ri 1 ri 1 1 m 1 - N nn?n,n! nnn 1 1 h n n nn n n n n h a i ini i i ini i III* C31N ism CAMPANIA i h h n n h h i r ~1 i j _____ e g g

Figure 25. 140

lesser amount of terrigenous material than the underlying sequence.

It includes white to pale brown, laminated to strongly bloturbated,

foraminifer-bearing muddy nannofossil chalk and muddy nannofossil

chalk. Unit V (281.1-317 mbsf) includes light gray to pale brown

muddy chalk, calcareous mudstone, and nannofossil-bearing mudstone

showing minor to moderate bioturbation. Chert beds and an ash horizon

occur In Core 113-690C-22X. A sharp contact between Unit V and

basaltic basement rock occurs at 317 mbsf in Core 113-690C-22X,CC.

As expected from the close proximity of Sites 689 and 690, the

foraminifer distribution patterns at Hole 690C are very similar to

those of Hole 689B. Foraminifer preservation is excellent in Unit V between Samples 113-690C-19X-2,119-123 and -21,CC (284-310 mbsf), where clay content is high. Preservation is good in all other samples examined (Fig. 25). Planktonic/benthic ratios are lower than for Hole

689B, with highest values (22%) just above basaltic basement. Benthic

foraminifers are less common in the overlying Cretaceous sequence, comprising less than 6% of the total diversity. Total planktonic diversity is less than 12 species for most of the sequence and reaches a maximum of 16 species in Sample 113-690C-19X-1,19-123 (Fig. 25).

Diversity is high in the upper Maestrichtian sequence below Sample

119-690C-16X,CC. This latter sample shows a decline in planktonic species diversity and an increase in the relative abundance of benthic

taxa.

The dominant planktonic foraminifers at Hole 690C are the same species that are most abundant in the Cretaceous sequence of Hole 689B

(Fig. 26; Appendices C, D). Archaeo globieerina australis is common to Figure 26. Distribution and relative abundance of upper Campanian through Maestrichtian planktonic foraminifers at Hole 690C. The plots are based on combined totals for 300 specimen counts of the >150 micron and <150 micron size fractions (Appendices C-D). Magnetostratigraphic information from Hamilton (in prep.). See Figure 24 for the key to relative abundance rankings and planktonic foraminifer zonal subdivisions.

141 H 2

* 3 +- i. m o m c • - - » 4 - 4 3 Q, M - T) 4 * — • « « • Q XJ 4 i- O C - « i. c C - 3 ♦* • * 4- - mm* e O •* 4 • *- a - • c 9 *• 3 C 3 V - V C 3 m E 3 c 9 3 * -> * 'I 0 o 4 m ■ - g • Z • » C H 3 V <- c O *• c o m -> i* -» u - 4 4 t> i- 4 m m * m * 3 m — z a. m z ( - 4 0 3 4 a 4 4 4 c c a • n 0 t 3 X • • • (- -0 O 0 ♦- 7 4 ODP SITE ■„ — TJ T3 m s i t n u - tj m 4 3 i- j» 4 C 4 4 c * o — ,» -.4 .4 — (• 4 - 4 4 (- m * o o o 0 — — 3 - o — — O o a » » — - z 1 w t» a 3 ~ • a 4 4 4 « 4 4 690 C C 4 C 4 C C 3 3 O a a • • * m x • <1 4 - 4 C 4 4 — -4 Q o o c c - X c o h L u 4 U 0 4 4 C - C — C U C C £ £ 4 o* o> t~ i- m « • 9 - *- 3 4 - 3 C 3 3 a a c o o « • t? £ Z Z O 9 t . a» ~ 3 <- i_ f i 4 - « ■ o> » O 0 0 ) i I f f i « +- i- +- 1- o O L- m m - — m L. L. i. 0-0 4 - 0 0 4- 0 O £ £ 4 z z a a z « « «l • J1 il £ 6 £ 0 £ £ *- — O O O O TJ «- ♦- zoo 3 4 0 9 O O 4 m a i. l. — n m • • * Q H ^ 4 3 - 3 — — £ a 3

16, CC 17-1, 119-123 17-3, 119-123 I 17, CC 18-1, 119-123 IB-2, 99-103 18-3, 98-102 18-4, 95-99 IB-3, 46-49 18,CC 19-1, 119-123 19-2, 119-123 19-3, 119-123 19-4, 119-123 O 19-3, 110-112 5 E 19-6, 119-121 E h 19, CC to 20-1, 118-121 20-2, 118-120 20-3, 116-110 20-4, 96-98 20-5, 108-1lO 20-6, 119-123 20, CC 21-1, 118-122 21 -2, 1 IB-122 21 -3, 118-122 21-4, 118-122 21 -3, 118-122 21, CC 22-1, 118-122 a. 22-2, 118-122 S 22-3, 107-111 < 22-4, 118-122 o 8 i

Figure 26. 143

abundant In nearly all samples, with the exception of the uppermost

Maestrlchtian. Archaeoplobieerina mateola also ranges throughout the

Cretaceous sequence at Hole 690C, occurring as a minor component of

the planktonic assemblages. Specimens of Globieerlnelloides impensns occur only at the bottom of Hole 690C (314 mbsf to 316 rabsf>, as at

Hole 689B. Both Globotruncanella havanensis and Hedbereella sliteri

first occur in lower Maestrlchtian Sample 113-690C-21X-5,118-122 and have a sporadic distribution above. The latter species is consistently present at higher abundances within the upper

Maestrlchtian sequence.

The conspicuous appearance of double keeled planktonic foraminifers in the upper middle Maestrlchtian sequence also occurs at

Hole 690C, beginning in Sample 113-690C-19,CC (Fig. 26; Appendix C).

Specimens of Rugotruncana circumnodifer and G1obo t rune ana subcircumnodifer are both present in this sample. These are followed by first appearances of G1obotruneana area in Section 113-69QC-19X-4,

Abathomohalus intermedius in Section 113-690C-19-1, and mavaroensis in Section 113-690C-18-5. The latter two species are key markers for the upper Maestrlchtian.

AGE DETERMINATIONS

Absence of upper Campanian and lower Maestrlchtian Tethyan planktonic foraminifer zonal species from the southern South Atlantic regions precludes recognition of the Campanian-Maestrichtian boundary by correlation with standard low latitude biostratigraphic zonal schemes (e.g., Caron, 1985). Nevertheless, Pospichal and Wise (in 144

prep.) state that Campanian sediments were not penetrated at either

Maud Rise site, based on the absence of several key calcareous

nannnoplankton species that have been found at other high southern

latitude sites. The magnetic polarity reversal stratigraphy at Site

690 (Hamilton, in prep.) is consistent with their findings, indicating

that the lowermost sequence recovered falls within Chron 33N, probably

just above the Campanian-Maestrlchtian boundary.

Globigerinelloides Imoensus Sliter occurs only in the lowermost

sections of Sites 689 and 690 at the Maud Rise. At Hole 689B, Q.

imoensus ranges from the base of the sedimentary sequence to Sample

113-689B-32X-1,41-43 (298.5-291.0 mbsf). Its range at Hole 690C is

from Sample 113-690C-22X-4,118-122 to Sample 113-690C-22X-3,107-111

(316.6-314.5 mbsf). Sliter (1977) reported that this species was

restricted to upper Campanian sediments at Falkland Plateau DSDP Site

327, occurring only in Core 36-327A-13R. This latter core is

separated from overlying Maestrlchtian sediments by a 23 m coring gap

(Fig. 27). Although Krasheninnikov and Basov (1983) reported £S.

lmpensus to range from Core 71-511-26R to -23R at Falkland Plateau

DSDP Site 511 (Fig. 22), re-examination of samples from that sequence suggests that this species is absent from the uppermost Cretaceous core. This species was probably mistaken for a similar form,

Globieerinelloides alvarezi (Eternod Olvera), which occurs in low abundance in Core 71-511-23R. Therefore, the last appearance datum

(LAD) of G. impensus at Site 511 is shown at the top of Core 71-51-24R

(Fig. 27), which was assigned to the late Campanian by Wind and Wise

(1983). Figure 27. Correlation of southern South Atlantic and Tasman Sea deep sea sites based on the highest occurrence (T) of Globigerinelloides impensus. the first appearance (B) of Globotruncanelia havanensis. and the highest occurrence of Abathomphalus mavaroensis. or absence of these species. All core sections (numbered in boxes) are scaled to their stratigraphic thickness and those that have relatively complete Cretaceous-Tertiary boundaries are scaled from the top of the Cretaceous sediments.

U 5 LATE CRETACEOUS CAMPANIAN MAE8TRICHTIAN lata•arly

■H

■>

m 147

Lower to middle Maestrichtlan sediments cannot be differentiated

based on planktonic foraminifers at either Maud Rise site because of

the absence of the zonal marker species Globotruncana falsostuarti. G.

tricarlnata. and G. ganserrl Bolli. Although the FAD (first

appearance datum) of G1ob o t rune ana subcircumnodifer is used to define

the lowermost Maestrlchtian in some low latitude sequences (e.g.,

Pessagno, 1967; Premoli Silva and Boersma, 1977), it has a delayed

first appearance at the Maud Rise. The FAD of this species is in

sediments assigned by Hamilton (in prep.) to the middle Maestrlchtian

at both Hole 689B and Hole 690C.

The first occurrence at Site 690 of Rueotruneana eircumnndifer is

within Chron 32N (291 mbsf), near the early-middle Maestrlchtian

boundary (Figs. 25), as determined by Hamilton (in prep.). g.

clrcumnodifer was present below the first appearance of 4 - intermedius

and A. mavaroensls at both Maud Rise sites, and also ranges below the

first occurrence of A. mavaroensis at DSDP Site 208 in the south

Tasman Sea (Webb, 1973b). Appearance of R. clrcumnodifer near the

early-middle Maestrlchtian boundary, within Chron 32N (Hamilton, in

prep.), suggests that this species may be a useful indicator for the

middle Maestrlchtian in high latitude regions.

The only Tethyan Cretaceous zonal marker species to occur at the

Maud Rise are Abathomphalus intermedius. which first appears in

Samples 113-689B-28X-2,80-84 and -690C-18X,CC, and 4- mavaroensis. which occurs just above A, intermedius at both sites. The FAD of 4. mavaroensis at Site 690 is within Chron 31R, which correlates with the upper Maestrlchtian, as defined at the Bottacione section near Gubbio, 148

Italy (Monechi and Thierstein, 1985). Based on the first occurrence

of 4* Intermedius. the boundary between the middle and late

Maestrichtian is placed about 258.5 mbsf in the Hole 689B sequence

(Fig. 23) and about 283.5 mbsf in Hole 690C (Fig. 25). The calcareous

nannoplankton zonal marker, Nephrolithis freauens Gorkd, has a

distribution at Sites 689 and 690 similar to that of mavaroensis

(Pospichal and Wise, in prep.) and thus confirms the late

Maestrichtian age assignment.

ZONAL SCHEME

Previous studies of Upper Cretaceous planktonic foraminifer

assemblages from the southern South Atlantic region were unable to

apply low latitude biostratigraphic schemes because zonal marker

species were absent (Sliter, 1977; Krasheninnikov and Basov, 1983,

1986; Huber, 1988). Foraminifer zonations proposed for Upper

Cretaceous high latitude sequences in New Zealand (Webb, 1971) and the

Antarctic Peninsula (Huber, 1988), shown in Fig. 28, are of limited

interregional utility because of incomplete stratigraphic reference

sections or local facies control on faunal distributions. Maud Rise

Sites 689 and 690 provide the most complete biostratigraphic range data for Maestrichtian planktonic foraminifers yet recovered from the high southern latitudes. Because low latitude zonal marker species are absent in much of the Maestrichtian sequence, a separate high latitude zonal scheme is proposed (Fig. 28). Applicability of this zonation for interregional correlation will be tested as other sites 149

SOUTHERN SOUTH ATLANTIC TASMAN Location SEA N Falkland Plataau 6 8 8 8 «00C 327A S11 208 Hoi*

24102820 1S46 Water depth (ro)

2 3 3 .4 247.8 186 676.S Top Cretaceoua (mbsf)

-10 3 4 - 1 5

-20

- 2 5 26 18

-30

- 3 5

18 -40 a late 30 - 4 5 {M\ 20

- 50 31

- 70 13 75 Figure 28. 151

yielding Upper Cretaceous foraminifers are recovered from the circum-

Antarctic region.

Globigerinelloides imoensus Total Range Zone

Definition. Interval from the first to last occurrence of £.

imoensus Sliter.

Age. Late Campanian to early Maestrichtian

Distribution. 113-689B-33X,CC through -32X-1,41-31 (298.3-291.2 mbsf); 113 -690C-22X-4,118-122 through -22X-3,107 - 111 (315.6-314.5 mbsf).

Globotruncanella havanensls Interval Zone

Definition. Interval from the last occurrence of

Globigerinelloides impensus to the first appearance of Abathomphalus mavaroensis.

Age. Early to middle Maestrichtian.

Diagnostic species. Globotruncanella havanensis (Voorwijk),

Archaeoelobigerlna australis n. sp,, A. mateola n. sp., Hedbereella monmouthensis (Olsson), and E. sliteri n. sp.

Distribution. 113-689B-30,CC through -28-2,80-84 (284.5-267.5 mbsf); -690C-22-2,118-122 through -18,CC (313.1-281.1 mbsf).

Aba thompha1us mavaroensis Total Range Zone

Definition. Interval from the first occurrence of &. mavaroensis to the extinction of planktonic foraminifers at the Cretaceous-

Tertiary boundary. 152

Age. Late Maestrichtian.

Distribution. L13-689B-28-1,76-80 through -25-5,90-88 (256.3-

233.7 mbsf); -690C-18-5,46-49 through -15-4,52-50 (277.9-247.9 mbsf).

CORRELATION OF HIGH SOUTHERN LATITUDE SITES

The three nominal taxa used in the zonal scheme presented above

are useful for high southern latitude correlation of upper Campanian

through upper Maestrichtian sequences. The LAD of Globigerinelloides

imoensus is 57.8 m below the Cretaceous-Tertiary boundary (K-T) at

Hole 689B, whereas the last appearance of this species at Hole 690C is

66.5 m below the youngest Cretaceous sediments (Fig. 27). The FAD of

Globotruncanella havanensis occurs at 42.3 m below the K-T at Hole

689B, whereas it occurs 16.9 m lower at Hole 690C. Abathompha1us mavaroensis first appears 22,9 m below the K-T at Hole 689B, but its

FAD is 10.3 m lower at Hole 690C. Thus, the Cretaceous sequence at

Site 690 is expanded relative to Site 689 by at least 9 m, probably as a result of the higher terrigineous input.

The upper Maestrichtian marker £. mavaroensis Zone was not recovered at either DSDP Sites 327 and 511 at the Falkland Plateau

(Fig. 27), and the nominal taxon of the £. havanensis Zone was found only at Site 327. The upper Campanian species G. impensus occurs in all samples from Core 13 at Site 327 and below the top of Core 24 at

Site 511.

The foraminifer distributions at these sites and their inferred ages are consistent with the revised calcareous nannoplankton biostratigraphy of Sites 327 and 511 proposed by Wind and Wise (1983). 153

These authors suggested an early to earliest middle Maestrichtian age for Cores 10 through 12 at Site 327. Core 13 from this site was dated as latest Campanian. Wind and Wise placed Core 23 of Site 511 in the earliest Maestrichtian and Core 24 in the latest Campanian.

DSDP Site 208 (Tasman Sea) also occupied a high paleolatitude

(50°S) during the Late Cretaceous. Webb (1973b) reported the FAD of mavaroensis in Section 21-208-33-2, 4.5 m below the top of the

Cretaceous sediments. Coring terminated at this site only 10 m below the A- mavaroensis Zone and therefore the FAD of G. havanensis and the

LAD of G. impensus were not reached (Fig. 7).

PALE0BI0GE0GRAPHY

THE AUSTRAL BIOGEOGRAPHIC PROVINCE

Upper Cretaceous planktonic foraminifers from the Maud Rise and other sites that occupied paleolatitudes poleward of 50°S are Included in the Austral Province. Scheibnerova (1971, 1973), Sliter (1977) and

Krashenninikov and Basov (1983, 1986) distinguished this cool- temperate biogeographic province from the Transitional (subtropical) and Tethyan (tropical) Provinces based on the absence of Upper

Cretaceous thermophilic planktonic foraminifers. Species of

Pseudotextularia. Racepuembelina. Ventrillabella. Planoelobullna.

Pseudogeumbelina. Plummerita. Trinitella and single keeled

Globotruncanlta are completely absent from the Austral Province and double keeled globotruncanids are very rare. No species were previously recognized as having distributions restricted to any of the extra-tropical provinces. Instead, Austral Province assemblages were 154

identified by having low species diversity and dominance of simple

globular species of the Heterohelicidae, Planomalinidae,

Hedbergellidae, and rare Rugoglobigerlnidae (Scheibnerova, 1971; Webb,

1973a; Sliter, 1977; Krasheninnikov and Basov, 1983).

Analysis of the Cretaceous foraminifer assemblages from the Maud

Rise, Falkland Plateau, and Kerguelen Plateau (see Chapter I) reveals

that several planktonic foraminifer species were restricted in their

paleobiogeographic distribution to the high southern latitudes.

Globigerinelloides impensus was previously known only from the

Falkland Plateau (Sliter, 1977; Krasheninnikov and Basov, 1983), but

its occurrence at the Maud Rise extends its paleobiogeographic range

to the eastern side of the southern South Atlantic. The new species

Archaeoglobleerina australis is not only a dominant component of the

Maud Rise assemblages, but it is also dominates the upper Campanian-

Maestrichtian assemblages at Sites 327 and 511. Considerable

morphologic variability of this species (see systematic discussion)

has led to substantial confusion in taxonomic concepts of the high

latitude morphotypes and incorrect age assignments for the species

that were misidentified. Detailed comparison and morphometric study

of large populations of australis from the Falkland Plateau and the

Maud Rise (Chapter II) has shown that specimens previously referred to

Rugoglobiyerina pilula Belford, £. rotundata Brdnniraann, and

Hedbergella monmouthensis (Olsson) by several authors (Sliter, 1977;

Krasheninnikov and Basov 1983; Huber, 1988) are in fact morphovariants

of the same species, here designated as Archaeoelobigerina australis.

Topotypes of the incorrectlyt identified species were morphometrically 155 compared with £. australis and their taxonomic distinction has been documented (Chapter II).

A third species determined to be restricted to the Austral

Province is Hedbergella sliteri (previously designated as fl. holmdelensis by Sliter, 1977 and H. monmouthensis by Huber, 1988).

Morphometric comparison of populations of this species from the Haud

Rise and the Falkland Plateau with topotypes of H. holmdelensis and H. monmouthensis (Chapter II) has also clarified their taxonomic differences (see also systematic discussion, this chapter). The paleobiogeographic range of H. sliteri extends to the southwest

Pacific, as Webb (1973b) reported identical forms, referred to as H. monmouthensis. from the Maestrichtian sequence of DSDP Site 208.

Planktonic specimens similar in morphology to the distinctive new species Archaeoglobiperina mateola (distinguished as Rugoglobigerlna sp. 2 by Huber, 1988) were found In one sample from lower

Maestrichtian sediments on Seymour Island (northern Antarctic

Peninsula). The absence of mateola from other austral localities is puzzling. The range of this species at the Maud Rise does overlap with the age of sediments recovered in Cores 10 through 12 of Falkland

Plateau Hole 327A (Fig. 27), but examination of samples from these cores has failed to reveal its presence. A. mateola is quite rare and somewhat sporadic in its occurrence within the lower to middle

Maestrichtian part of its range at the Maud Rise. Thus its absence from the Falkland Plateau cannot be entirely substantiated until the existing material is studied further or until younger Maestrichtian sediments are recovered from that region. 156

PALEOENVIRONMENTAL INFERENCES

The most important factor controlling Cretaceous planktonic foraminifer paleobiogeography has been interpreted to be the arrangement of paleoclimatic belts (Douglas, 1969; Sliter, 1972, 1977;

Krashininnikov and Basov, 1986). On the basis of foraminifer distributions on the Falkland Plateau, Krasheninnikov and Basov (1983,

1986) constructed a paleoclimatic curve for the Early and Late

Cretaceous in the southern South Atlantic region (see Chapter I, Fig.

7). Absence of keeled taxa and dominance of simple globigerine species of Heterohelix. Globigerinelloides. and Hedbereella were used as indicators of cold conditions, while warm periods were recognized by the presence of high diversity assemblages yielding stenothermal keeled species.

If this model is used to reconstruct the paleoclimatic history of the Maud Rise, a significantly different history of late Campanian-

Maestrichtian climate arises. The curves of Krasheninnikov and Basov

(1983, Fig. 5; 1986, Fig. 7) show a stepwise cooling from the late

Campanian through the Maestrichtian, with a substantial cooling at the

Cretaceous-Tertiary boundary. However, the late Maestrichtian part of the curve was drawn without data from southern South Atlantic planktonic foraminifer assemblages of that time period. The trend in diversity of the Maud Rise fauna increases through the Maestrichtian and reaches a maximum in the early part of the late Maestrlchtian

(Figs. 23, 25). This diversity increase is accompanied by an influx of keeled planktonic foraminifers, morphotypes that are completely 157

absent from the Globigerinelloides Impensus Zone and the lower part of

the Globotruncanella havanensis Zone at Sites 689 and 690. The FAD of

the keeled species Globotruncana subcircumnodifer and G. area at both

Maud Rise sites is In the upper part of the G, havanensis Zone,

although these species range into older sediments elsewhere.

The diachronous appearance of thermophilic keeled species with

other low latitude marker species, including Globotruncanella

petaloidea and Globigerinelloides subcarinatus. in the middle and

upper Maestrichtian sequence may have been caused by a poleward

expansion of the warmer biogeographic provinces. This interpretation

is consistent with results from middle latitude paleobotanical and

plant physiogonomy studies in the Northern Hemisphere by Wolfe (1987), which indicate a late Maestrichtian warming event. However, this expansion has not been recognized in previous oxygen isotope paleotemperature studies (e.g.. Savin, 1975; Barrera et al,, 1987), nor from isotopic paleotemperture analyses of the Maud Rise foraminifers (Barrera and Huber, in prep.).

On the other hand, the increase in species diversity and poleward migration of keeled morphotypes may have been caused by enhanced vertical stratification of the high southern latitude surface waters.

Keeled Cretaceous species, inferred to have grown in deep surface water habitats (Hart, 1980), were probably excluded from highly convective surface waters, as their inferred longer life cycles would have required a density-stratified water column (Caron and Homewood,

1983). Because of the more strongly seasonal environment, it can be assumed that surface waters in high latitude regions have always been 158 more poorly stratified than those in the tropics. If Cretaceous planktonic morphotype diversity was directly dependent on surface water stratification, than the dominance of simple, globular forms in

the Maud Rise sequence reflects predominantly convective surface water conditions during the late Campanian through early middle

Maestrichtian. The influx of keeled species during the late middle and late Maestrichtian suggests a period of increased surface water stratification, perhaps due to higher temperatures and more sluggish surface water circulation. However, oxygen and carbon isotope analyses of planktonic and benthic foraminifers from the Maud Rise

(Barrera and Huber, in prep.), reveal no correlative changes in vertical and latitudinal temperature gradients to support the increased surface water stratification model.

As Cifelli and Scott (1986, p. 66) noted, "...the parallels of latitude are man-made constructs and not, in themselves, natural phenomena". Cretaceous planktonic foraminifer distributions were probably influenced by many factors other than the arrangement of climatic belts or stratification of the surface waters. It is well known that many biotic and abiotic parameters affecting modern foraminifer distributions cannot be measured in the fossil record.

Therefore, it should not be surprising when stratigraphic changes in diversity and relative abundance of planktonic foraminifers do not parallel changes in the stable isotopic composition of the seawater in which they grew. A better understanding of factors controlling the distribution patterns observed from the Upper Cretaceous planktonic 159

foraminifers from the Maud Rise must await detailed analysis of coeval

assemblages from other high latitude, deep sea sites.

SYSTEMATIC DESCRIPTIONS

All planktonic foraminifer species encountered in this study are discussed below and are illustrated on Plates 12-17. Synonomy lists

are limited to the original reference, with additional synonomies added for clarification of taxonomic uncertainties among some species.

Three species are formally described as new. Details of their morphologic variability, distinction from other taxa, size range, and stratigraphic distribution are also provided, Holotypes and paratypes of each new species will be deposited at the U.S. National Museum in

Washington, D.C. Discussion of some previously described taxa is included to elucidate differences in morphologically similar or phyletically related forms.

GUEMBELITRIA CRETACEA CUSHMAN

(PI. XII, Fig. 1)

Guembelltria cretacea Cushman, 1933, p. 37, PI. 4, Figs. 12a-b,

Occurrence. First appears in Samples 113 -689B-29X,CC and -690C-

21X-5,116-122 and sporadically occurs in low abundance through the younger Maestrlchtian sequence. Caron (1985) and other authors have noted that the range of this species is restricted to the

Maestrichtian stage. 160

HETEROHELIX GLABRANS (CUSHMAN)

(PI. XII, Fig. 2)

Guembelina elabrans Cushman, 1938, p. 15, PI. 3, Figs. 1-2.

Occurrence. Occurs in all Cretaceous samples at Sites 689 and 690 in very rare to high abundance. Ranges from the upper Campanian through Maestrichtian elsewhere.

HETEROHELIX GL0BUL0SA (EHRENBERG)

(PI. XII, Fig. 3)

Textularia globulosa Ehrenberg, 1840 (1838), p. 135, PI. 4, Figs. 2B,

4B, 5B, 7B, 8B.

Occurrence. Present in all Cretaceous samples at Sites 689 and

690 in rare to high abundance. A common component of Upper Cretaceous assemblages worldwide.

HETEROHELIX PULCHRA (BROTZEN)

(PI. XII, Figs. 4-6)

Guembelina pulchra Brotzen, 1936, p. 121, PI. 9, Figs. 3a-b.

Occurrence. Occurs throughout the Cretaceous of Sites 689 and

690, occurring in rare to high abundance. Its range has been established as Coniacian through Maestrichtian elsewhere,

GUBLERINA COMPRESSA (VAN DER SLUIS)

(PI. XII, Fig. 7)

Ventilabrella compressa van der Sluis, 1950, p. 20, PI. 1, Figs. la- c . 161

Occurrence. Restricted to the Abathomphalus mavaroensi s Zone at

Sites 689 and 690. Originally reported from the Maestrichtian of

Indonesia.

GLOBIGERINELLOIDES ALVAREZI (ETERNOD OLVERA)

(PI. XII, Figs. 10, 16)

Planomallna alvarezl Eternod Olvera, 1959, p. 91, PI. 4, Figs. 5-7.

Remarks. This species differs from Globigerinelloides multisoinatus (Lalicker) by its greater number of chambers in the final whorl (commonly 6-7), finer surface ornament, thinner test and broader umbilicus. It is distinguished from G. impensus Sliter by having fewer chambers in the final whorl, its smaller size, and having a more broadly rounded equatorial periphery.

Occurrence. Sporadically is very rare throughout the Cretaceous at Sites 689 and 690. It was originally described from Garapanian-

Maestrichtlan sediments from Mexico and has been reported from the

Santonian-Maestrichtian elsewhere.

GLOBIGERINELLOIDES IMPENSUS SLITER

(PI. XII, Figs. 8-9)

Globigerinelloides imoensus Sliter, 1977, p. 541, PI. 6, Figs. 1-3.

Krasheninnikov and Basov, 1983, p. 803, PI. 2, Figs. 4-6.

Occurrence. This is the nominal taxon of the £. im p e n su s Zone, ranging within the uppermost Campanian at the Maud Rise and Falkland

Plateau. It occurs from the bottom of Holes 689B and 690C to Samples

113-689B-32X-1,41-43 and -690C-22X-3,107- 111. 162

GLOBIGERINELLOIDES MULTISFINATUS (LALICKER)

(PI. XII, Figs. 11-13)

Bieloblgerinella multlspinatus Lalicker, 1948, p. 624, PI. 92, Figs.

1-3.

Occurrence. One of the most common components of upper Campanian-

Maestrlchtian assemblages from the high southern latitudes. Uni- and bicameral forms occur in few to high abundance throughout the upper

Carapanian-Maestrichtian sequence at the Maud Rise.

GLOBIGERINELLOIDES SUBCARINATUS (BRONNIMANN)

(PI. XII, Figs. 14-15)

Globigerlne11a messinae subcarinata Brdnnimann, 1952, p. 44-45, PI. 1,

Figs. 10-11, Text-figs. 21a-m.

Occurrence. Restricted to the Abathomphalus mavaroensis Zone at the Maud Rise. Bronnimann originally described this species from

Trinidad strata also assignable to the A. mavaroensis Zone and it is restricted to this zone in the American Gulf Coast region (Pessagno,

1967).

SCHACKOINA MULTISPINATA (CUSHMAN AND WICKENDEN)

(PI. XIII, Fig. 1)

Hantkenlna multispinata Cushman and Wickenden, 1930, p. 40, PI. 6,

Figs. 4-6.

Occurrence. This species occurs in very rare abundance from the base of the Globigerinelloides impensus Zone at both Maud Rise sites 163

up to the base of the Abathomphalus mavaroensis Zone. It is commonly

found in Upper Cretaceous sediments worldwide.

HEDBERGELLA HOLMDELENSIS OLSSON

(PI. XIII, Figs. 2-4; PI. XVII, Fig. 1)

Hedbereella holmdelensis Olsson, 1964, p. 160, PI. 12, Figs. 1-2.

not Hedbereella holmdelensis Olsson. Sliter, 1977, p. 542, PI, 3,

Figs. 1-3.

Remarks. This species is distinguished from H. monmouthensis

(Olsson) by its larger size (up to 300 microns in diameter), by having

a more compressed test and by the asymmetry of the final chamber face.

Topotypes of this species were compared with the Maud Rise specimens

and found to be identical in external and internal (Pi. XVII, Fig. 6)

morphology. It differs from H. sliteri by its smaller size and

narrower, deeper umbilicus.

Occurrence. Very rare at the Maud Rise, occurring in the

Globigerinelloides impensus Zone and the lower Globotruncanella havanensis Zone. Re-examination of material from the Falkland Plateau

indicates its range extends from Section 36-327A-13R-2 through -12R-2 and Section 71-511-41R-3 through -28R-7, which have been dated as

Campanian through early to early middle Maestrichtian (Wind and Wise,

1983). Caron (1985) reported that H. holmdelensis ranges from the

Coniacian through Maestrichtian, but this extensive range is probably an artifact of confused taxonomic concepts. 16 4

HEDBERGELLA MONMOUTHENSIS (OLSSON)

(PI. XIII, Figs. 6-8; PI. XVII, Fig. 2)

Globorotalia monmouthensis Olsson, 1960, p. 74, PI. 9, Figs. 22-24.

not Hedbergella monmouthensis (Olsson). Sliter, 1977, p. 542, Pi. 3,

Figs. 1-3. Krasheninnikov and Basov, 1983, p. 805-806, PI. 6, Figs.

5-8. Huber, 1988, p. 206, Figs. 24.14-17.

Remarks. This species has frequently been confused with similar juvenile forms of other species. It is distinguished by its small size (less than 200 microns diameter), chambers that increase moderately in size, and symmetrically globular final chamber face.

The ontogenetic morphology of the Maud Rise forms were compared with topotypes (PI. XVII, Fig. 2) of this species and found to be identical.

Occurrence. Incorrect identifications of IJ. monraouthens 1 s have led to uncertainty in its stratigraphic distribution. Robaszynski et al, (1984) suggest that it ranges from the lowermost Campanian through the Maestrichtian, whereas Olsson (1987) maintains that this species evolved from H. holmdelensis during the early Maestrichtian. At the

Maud Rise, H. monmouthensis ranges from the Globigerinelloides impensus Zone through the Abathomphalus mavaroensis Zone. Re - examination of the stratigraphic distribution of H. monmouthens is at the Falkland Plateau indicates its first appearance is in upper

Campanian Samples 36-327A-13R-2 and 71-511-24R-7.

HEDBERGELLA SXITERI N. SP.

(PI. XIII, Figs. 5, 9-10; PI. XVII, Figs. 4-5) 165

Hedberyella monmouthens is (Olsson). Webb, 1973b, p. 552, PI. 3, Figs.

1- 2 .

Hedbereella holmdelensis Olsson. Sliter, 1977, p. 542, PI. 2, Figs. 1-

Hedbereella monmouthensis (Olsson). Huber, 1988, p. 206, Figs. 27.14-

17.

Etymology. Named for W. V. Sliter (USGS, Menlo Park), a pioneer

in the study of Upper Cretaceous planktonic foraminifer biogeography

of the southern South Atlantic.

Diagnosis. Test nearly planlspiral to low trochospiral, chambers

gradually increasing in size, five to six in final whorl, umbilicus broad and shallow, aperture a low extra-umbilical arch bordered by a porticus near the equatorial periphery.

Description. Test coiled in a low trochospire and sometimes nearly planlspiral, often flattened on the spiral side, convex on the umbilical side, average diameter 273 microns, average breadth 123 microns. Chambers inflated, slightly reniform to globular, increasing gradually in size, usually five to six in the final whorl, four and one-half to six in the penultimate whorl, 12 to 15 comprising the entire test of adult specimens, final chamber normalform or kummerform. Proloculus diameter averaging 17 microns, initial whorl diameter averaging 74 microns, with a mean of 5.0 chambers in the initial whorl. Sutures strongly depressed, radial and straight on the spiral and umbilical sides. Umbilicus shallow, broad, averaging 28% of the maximum test diameter. Aperture a low, interiomarginal arch, extra-umbilical, sometimes positioned very near the equatorial 166

periphery, bordered by a narrow porticus. Relict apertures and

apertural flaps well-developed. Test surface nearly smooth to finely

pustulose, outer wall radial hyaline, finely perforate.

Remarks. Populations of this species were compared with topotypes

of H. H. monmouthensis (Olsson) from the Red Bank Formation (New

Jersey) and illustrations of H. holmdelensis Olsson and g.

monmouthens 1s provided by R. K. Olsson (pers, comm., 1987). H.

sliteri differs by its larger size, chambers that increase more

gradually in size, fewer number of chambers in the penultimate whorl

and broader umbilical region. The frequency of specimens with

kuramerform final chambers is higher among the Maud Rise assemblages

than those of the Falkland Plateau.

Occurrence. At the Maud Rise, H. siiteri ranges from the

Globotruncanella havanensis Zone through the Abathompha1us mavaroensis

Zone, occurring in very rare to common abundance. It is a common

component of samples correlated with the G. havanensis Zone at the

Falkland Plateau, occurring only within Cores 36-327A-12 through 36-

327A-10. It was not in any samples examined from the

Globigerinelloides impensus Zone. Forms described by Webb (1973b)

from Lord Howe Rise DSDP Site 208 are also middle to late

Maestrichtian in age. This species is considered to be endemic to the

Austral Province.

Holotype. (PI. XIII, Figs. 5, 9-10). Maximum diameter: 370 microns, maximum breadth: 155 microns.

Type locality. Maud Rise, southern South Atlantic, Sample 113-

690C-18X-5,46-49. 167

ARCHAEOCLOBIGERINA AUSTRALIS N. SP.

(PI. XIII, Figs. 11-13, PI. XIV, Figs. 1-7; PI. XVII, Figs. 7-9)

Hedbereella monmouthensis (Olsson), Sliter, 1977, p. 542, PI. 3, Figs.

1-3. Krasheninnikov and Basov, 1983, p. 804-805, PI. 6, Figs, 5-8.

Rugoglobieerina pilula Belford, Sliter, 1977, p. 542, PI. 120, Figs.

7-9. Krasheninnikov and Basov, 1983, p. 807, PI. 11, Figs. 3-6.

RueoglobleerIna pustulate BrOnnimann, Krasheninnikov and Basov, 1983, p. 806, PI. 10, Figs. 10-13.

Rugog1obieerlna rotundata Bronnimann, Sliter, 1977, p. 543, Pi. 11,

Figs. 1-3. Krasheninnikov and Basov, 1983, p. 807, Pi. 11, Figs. 7-

11. Huber, 1988, p. 206, Figs. 28.12-14.

Etymology. From australis (latin), referring to the southern latitude region where it is found.

Diagnosis. Test biconvex, moderate to high spired, chambers strongly inflated, globular, final whorl chambers on adult specimens four to six, Increasing moderately in size, adult apertures umbilical to slightly extra-umbilical with a broad flap, surface composed of randomly situated pustules.

Description. Test coiled in a moderate to high spire, inequally biconvex, spiral side usually more convex than umbilical side, average diameter of adult specimens 280 microns, average breadth 150 microns.

Chambers strongly inflated, globular, increasing moderately in size with four to five and one-half In the penultimate whorl, increasing gradually in size with three and three-quarters to five and three- quarters in the ultimate whorl, 12 to 15 comprising the tests of adult 168 specimens, final chambers usually kummerform. Proloculus diameter of adult specimens averaging 16 microns, initial whorl diameter averaging

71 microns, with a mean of 4.4 chambers in the initial whorl. Sutures moderately to strongly depressed, radial and straight on both the spiral and umbilical sides. Apertures of juvenile specimens extra- umbilical in position, having greater width than height, bordered by a narrow, thickened lip. Apertures of adult specimens umbilical to slightly extra-umbilical in position, often bordered by a broad flap that may completely extend across the umblicus, with relict apertural flaps sometimes coalescing to form a pseudo-tegillum. Umbilicus deep, narrow to broad, comprising an average of 28% of the maximum test diameter. Test surface covered with fine to coarse, randomly situated pustules, surface of final chamber usually with finer pustulose ornament than previous chambers. Outer wall radial hyaline and finely perforate.

Remarks. Although end member morphotypes included in this species show considerable differences in chamber development and apertural characteristics (e.g., compare PI. XIII, Figs. 11-12 with PI. 3, Figs.

2-4), no distinct populations could be recognized as a separate species in the Maud Rise and Falkland Plateau assemblages. Serial dissection of large, adult specimens (PI. XIII, Fig. 13) and x-ray micrographs (PI. XVII, Figs. 7-9) reveal penultimate whorl morphologies identical to small forms (PI. XIII, Figs. 11-12), here considered as neanic specimens of australis.

Gerontic forms of australis resemble specimens of bosauensls

Pessagno that were described from Santonian sediments in the western 169

Gulf Coastal Plain (Pessagno, 1967) and the Falkland Plateau (Sliter,

1977; Krasheninnikov and Basov, 1983). The Gulf Coast holotype and paratype of A- bosauensis differ from A- australis by having a smoother test surface and lacking kummerforoi chambers and apertural flaps. However, poor preservation of the type material and uncertainty of the morphologic variability among Gulf Coast populations of A- bosauensis preclude an adequate comparison of these taxa. Falkland Plateau specimens described as A* bosauensis. which are very well preserved and occur in high abundance, do not bear apertural flaps, are generally higher spired and have a narrower, deeper umbilicus than most forms of A. australis. although some forms of the latter species (e.g., PI. XIV, Fig. 7) are very similar. The stratigraphic interval separating these two species and their morphologic similarity suggest that A- australis is a descendant of A- bosauensis.

No specimens had well developed tegilla, imperforate peripheral margins, peripheral keels, or meridionally arranged costellae.

Therefore, this species is not placed in Rugoglobigerina or

Rugotruneana. Inclusion in Archaeoelobigerina differs from the original description of that genus, which suggests that tegilla should be observed in "perfectly preserved specimens" (Pessagno, 1967, p.

315). Because this structure is absent from the Gulf Coast type species of Archaeoglobigerina (A- blowi Pessagno) and A- bosquensis. it is not considered as a primary generic character. Either the definition of this genus needs to be modified, or a new genus should be created to accomodate the non-keeled, non-tegillate forms. 170

Occurrence. australis dominates the Maud Rise planktonic foraminifers from near the bottom of the Cretaceous sections at Holes

689B and 690C up to the middle Abathomnhalus mavaroensis Zone. It is also a dominant component of the upper Campanian through lower

Maestrichtian assemblages at Falkland Plateau DSDP Sites 327 and 511 and is very rare on Seymour Island (see synonomy above). Its first appearance at the Falkland Plateau is in lower Campanian Sample

71-511-30-4,61-63 (pers. observ.).

Holotype. (Pi. XIV, Figs. 2-4). Maximum diameter: 334 microns, maximum breadth: 190 microns.

Type locality. Maud Rise, southern South Atlantic, Sample 113-

690C-19X-3,119-123.

ARCHAEOCLOBIGERINA MATEOLA N. SP.

Rueoglobieerina? sp. 2, Huber, 1988, p. 207, Figs. 31.12, 15-16.

Etymology. From mateus (latin), a medieval war club with a blunt, spiny terminus.

Diagnosis. Test moderate to high spired, often inequally biconvex, chambers increasing moderately in size, three and three- quarters to four and one-half in final adult whorl, adult aperture umbilical, often covered by a flap or thickened bulla, final chambers usually kummerform, surface distinctly ornamented by coarse pustules or long, narrow spines.

Deacription. Test coiled in a moderate to high spire, equally to inequally biconvex, spiral side often more convex than umbilical side, 171

average diameter of adult specimens 280 microns, average breadth 190

microns. Chambers globular, inflated, increasing moderately in size,

three and three-quarters to four and one-half in the final adult

whorl, four to four and one-half in the penultimate whorl, 10-12

comprising the tests of adult specimens, final chambers usually

kummerform. Proloculus diameter averaging 17 microns, initial whorl

diameter averaging 74 microns, with a mean of 4.5 chambers in the

initial whorl. Sutures radial and straight, strongly depressed on

umbilical side, moderately depressed on spiral side. Aperture

umbilical in position on adult specimens, usually obscured by a broad

flap or thickened umbilical bulla. Apertures of juvenile specimens umbilical to extra-umbilical, having greater width than height.

Surface distinctly ornamented with randomly situated, large pustules or high, narrow spines on adult specimens, smooth to finely pustulose

on juveniles. Outer wall radial hyaline and finely perforate.

Remarks. This species has a very unusual external morphology compared with other known Upper Cretaceous planktonic foramlnifer

taxa. Similarity in the ontogenetic development of this species suggests a close ancestral relationship with australis (Huber, in prep.). Inclusion in Archaeoplobigerina is primarily because of the rugoglobigerine chamber arrangement and absence of meridional costellae. No tegilla nor peripheral keel bands were present among the Maud Rise populations, however, so similarity to the original definition of Archaeoelobigerina (see Pessagno, 1967, p. 315) is limited. 172

Occurrence, At the Maud Rise, this species occurs in very rare abundance in the Globigerinelloldes imoensus Zone and lower

Globotruncana havanenesls Zone, and rare to common abundance through the Abathomphalus mavaroensls Zone. Very rare occurrences of this species were reported by Huber (1988; see synonomy above) from one sample in the lower Maestrichtian of Seymour Island (Antarctic

Peninsula).

Holotype. (PI. XIV, Figs, 8-10). Maximum diameter: 301 microns, maximum breadth: 215 microns.

Type locality. Maud Rise, southern South Atlantic, Sample 113-

690C-20X-3,116-118.

RUGOTRUNCANA CIRCUMNODIFER (FINLAY)

(PI. XV, Figs. 4-10; PI. XVII, Fig. 3)

Globigerina circumnodifer Finlay, 1940, p. 469, PI. 65, Figs. 150-157.

Globotruncana (Rueotruncana) circumnodifer (Finlay), Uebb, 1973b, p.

552, PI. 4, Figs. 1-4.

Remarks. This species is distinguished by having strongly inflated chambers numbering four to five and one-half in the final whorl and paired keels on the equatorial periphery. The keels are usually not visible on the ultimate chambers and are sometimes only expressed by an imperforate peripheral band (e.g., PI. XV, Figs 8-9).

Surface ornament varies from randomly situated, small pustules to well-developed costellae aligned in a meridional pattern. Tegilla are usually preserved on the Maud Rise specimens. 173

Occurrence. This species was first described by Finlay (1940)

from New Zealand where it occurs with Abathomphalus mavaroensis (Webb,

1971). g. ci rcvunnodlfer was also reported from DSDP Site 208 in the

Tasman Sea (Webb, 1973b). A single specimen resembling this species,

referred to as Rueotruncana cf. g. circumnodifer. was found on Seymour

Island (Antarctic Peninsula) in the lower Hedbergella monmouthens1s

Zone (Huber, 1988). At the Maud Rise, E- circumnodifer first appears

in the upper Globotruncanella havanensis Zone and ranges through the

Abathomphalus mavaroensis Zone. It is uncertain whether g. circumnodifer was restricted to the Austral Province, as it may have been confused with other globular, double keeled species, such as

Rugotruneana subpennyi (Gandolfi).

GLOBOTRUNCANELLA HAVANENSIS (VOORWIJK)

(PI. XVI, Figs. 1-2)

Globotruncana havanensis Voorwijk, 1937, p. 195, Pi. 1, Figs. 25-26.

Occurrence. This is the nominal taxon of the G. havanensis Zone at the Maud Rise. It appears above the 1AD of Globigerinelloides lmpensus in Samples 113-689B-30X-1,83-85 and 113-690C-21X-5,118-122 and ranges into the Abathomphalus mavaroensis Zone, occurring in very rare to rare abundance. Caron (1985) and others report that £. havanensis ranges from the uppermost Campanian through the

Maestrichtian.

GLOBOTRUNCANELLA PETALOIDEA (GANDOLFI)

(PI. XV, Fig. 11) 174

Globotruncana (Rupoglobieerina) petaloldea Gandolfi, 1955, p. 52, PI,

3, Fig. 13.

Globotruncanella? sp., Huber, 1988, p. 208, Figs. 31.4., 31.7-31.8.

Occurrence. This species is restricted to the Abathomphalus mavaroensis Zone at the Maud Rise. A single specimen of £. petaloidea. previously identified as Globotruncanella? sp., occur only in the uppermost Maestrichtian beds on Seymour Island in the northern

Antarctic Peninsula (Huber, 1988). Its stratigraphic range is from the lower through upper Maestrichtian at other localities.

ABATHOMPHALUS INTERMEDIUS (BOLLI)

(PI. XVI, Figs. 5-6)

Globotruncana intermedia Bolli, 1951, Pi. 35, Figs. 7-9.

Occurrence. This species appears just below the FAD of £- mayaroensis at Maud Rise Sites 689 and 690, occurring in very rare abundance, Caron (1985) reports that the stratigraphic distribution of 4- intermedius is limited to the upper Maestrichtian, ranging from the middle of the tropical Gansserina panserri Zone through the mavaroensis Zone.

ABATHOMPHALUS MAYAROKNSIS (BOLLI)

(PI. XVI, Figs. 3-4)

Globotruncana mavaroensis Bolli, 1951, p. 190, 198, PI. 35, Figs, 10-

12.

Occurrence. This is the nominal taxon for the mavaroensis

Zone, which is recognized worldwide as being late Maestrichtian in 175

age. The FAD of this species at the Maud Rise is in Samples 113-689B-

28X-1,76-80 and 113-690C-18,CC and it occurs up to the Cretaceous-

Tertiary boundary contact at both sites.

GLOBOTRUNCANA ARCA (CUSHMAN)

(PI. XVI, Figs. 9-11)

Pulvinullna area Cushman, 1926, p. 23, PI, 3, Figs. la-c.

Occurrence. This species first appears in the middle of the

G1obotruneane11a havanensis Zone and occurs sporadically in very rare

abundance in the Abathomphalus mavaroensis Zone at the Maud Rise. It was also found in the uppermost Cretaceous samples at Falkland Plateau

Hole 327A (Sliter, 1977), which are correlative to the

Globotruncanella havanensis Zone. G. area is reported as ranging from the G. elevata Zone to within the A. mavaroensis Zone at lower latitude sites (Caron, 1985). Thus, Its first occurrence in the middle Maestrichtian at the Maud Rise considerably post-dates its first evolutionary appearance in tropical to subtropical regions.

This poleward migration may have occurred because of meridional expansion of the warmer water Transitional Province.

GLOBOTRUNCANA SUBCIRCUMNODIFER (GANDOLFI)

(PI. XVI, Figs. 7-8, 12)

Globotruncana (Rugoelobigerina) subcircumnodifer Gandolfi, 1955, p.

44, PI. 2, Figs. 7a-c.

Occurrence. This species ranges from the upper part of the

Globotruncana havanensis Zone through the Abathomphalus mavaroensis 176

Zone at the Maud Rise, occuring in very rare to rare abundance. As it

is reported to first appear in the upper Globotruncana calcarata Zone

(upper Campanian) at lower latitude sites (Caron, 1985), the FAD of G.

subcircumnodifer in the southern South Atlantic is regarded as

resulting from its poleward migration from warmer water regions.

CONCLUSIONS

The oldest sediments recovered from Maud Rise Sites 689 and 690

are determined to be earliest Maestrichtian in age. Absence of key

marker species from all but the upper Maestrichtian part of both sites

precludes accurate determination of sedimentation rates and hiatuses

in the Cretaceous sediments. Nevertheless, some conclusions may be

drawn from stratigraphic comparisons of the distribution of several

planktonic foraminifer species between the two sites: 1). The oldest

sediments at both Maud Rise sites are nearly the same age, with the

bottom of the Hole 689B sequence determined to be slightly older than

that of Hole 690C; 2). The thickness of Cretaceous sediments at Site

690C is expanded by at least 10 m relative to those of Site 689B, probably because of higher terrigenous input; and 3). Sediments

asssigned to the upper Maestrichtian comprise 42%-50% of the total

Maestrichtian sequence, which is considerably greater than at complete

sections recovered from other localities. This may be attributed to

the presence of one or several hiatuses in the lower to middle

Maestrichtian units. 177

An important result of drilling the Maud Rise sites is a

substantially improved biostratigraphic framework for the upper

Campanian through Maestrichtian in high southern latitudes. In the

present study, the Globieerinelloides imoensus Zone is only recognized

at sites in the southern South Atlantic region, but it may be found at

other Austral Province sequences in the southern Indian Ocean and

southwest Pacific. The Globotruncanella havanensis Zone and

Abathomphalus mavaroensis Zone can be correlated with lower latitude

zonal schemes, and thus permit subdivision of Maestrichtian sediments

in the extra-tropical regions.

Foraminifer assemblages from the G. impensus and lower £.

havanensis Zones at the Maud Rise are identical to upper Campanian and

lower Maestrichtian assemblages reported from Falkland Plateau DSDP

Sites 327 and 511. They are characterized by low diversity, absence

of keeled and strongly ornamented forms, and share three species whose

distribution is presently known only from the Austral Province. A

watermass boundary separating a warm, subtropical gyre from a cool,

extra-tropical gyre was inferred to have been situated over the

northern Falkland Plateau during late Campanian through early

Maestrichtian time (Cielsielski et al., 1977). Occurrence of

thermophilic keeled planktonic foraminifers in the upper £. havanensis

Zone and A. mavaroensis Zone suggests that this boundary either moved

poleward or vanished during the late middle Maestrichtian through late

Maestrichtian. This may have been caused by a high latitude warming

event that has not been recognized by previous oxygen isotope

paleotemperature studies. On the other hand, the poleward migrations 178

of thermophilic species may have resulted from enhanced vertical

stratification of the water column in the high latitudes due to less

vigorous surface water convection. However, neither model is

substantiated based on results from oxygen and carbon isotopic analyses of Cretaceous Maud Rise planktonic and benthlc foraminifers

(Barrera and Huber, in prep.). Plate XII. 1. Guembelitria cretacea Cushman, Sample 119-690C-20X- 3.116-118. 2. Heterohellx glabrans (Cushman), Sample 119-690C-19X- 1.119-123, 3, Heterohelix globulosa (Ehrenberg), Sample 119-690C-17X- 3.119-123. 4, Heterohelix pulchra (Brotzen), Sample 119-690C-19X- 1.119-123, 5-6. Heterohelix Pulchra (Brotzen), Sample 119-690C-20X- 3.116-118. 7. Gublerina compressa (van der Sluis), Sample 119-690C- 18X-4,95-99. Globleerinelloides alvarezi (Eternod Olvera), Sample 119-689B-30X-3,78-83. Globieerlnelloides impensus Sliter, Sample 119- 690C-22X-4,118-122. 11-12. Globigerinelloides multispinatus (Lalicker), Sample 119-690C-20X-5,108-110. 14-15. Globleerinelloides subcarinatus (Bronnimann), Sample 119-690C-17X-3,119-123. Scale bar for Fig. 1 is 25 microns and for Figs. 2-16 is 50 microns.

179 180 Plate XII Plate XIII. 1. Schackolna multlspinata (Cushman and Ulckenden), Sample 119-690C-20X-5, 108-110. 2-4. Hedbereella holmdelensis Olsson, Sample 119-690C-21X-4, 118-122. 5, 9-10. Hedberpella sliterl n. sp., holotype, Sample 119-690C-18X-5,46-49. 6-8. Hedbereella monmouthensis (Olsson), Sample 119-690C-20X-5, 108-110. 11-12. Archaeogloblgerlna australis n, sp., neanic specimen, Sample 119-690C-19X,CC. 13. Archaeoglobigerlna australis n. sp., Sample 119-690C-20X-3. View of with final adult whorl removed, showing similarity of penultimate whorl chambers to neanic specimen of Figs. 11-12. Scale bar for Figs. 1 -13 is 50 microns.

181 182

Plate XIII Plate XIV. 1, Archaeoglobigerina australis n . sp., s .s., Sample 119-690C-19X-3,119-123. Note the considerable varlablity of chamber development, umbilical size, and apertural flaps. 2-4. Archaeoglobigerina australis n. sp., holotype, Sample 119-690C-19X-3, 119-123. 5. Archaeoglobigerina australis n. sp., s.l. , Sample 119- 690C-19X-3,119-123. 6. Archaeoelobiperina austral is n. sp., s.l., Sample 119-689B-30X-3,83-87. 7. Archaeoglobigerina australis n. sp., s.l., Sample 119-689B-28X-3,83-87. 8-10. Archaeoglobigerina mateola n. sp., holotype, Sample 119-690C-20X-3,119-123. Scale bar for Figs. 1-10 is 50 microns.

183 184

Plate XIV Plate XV. 1. Archaeoglobigerina mateola n. sp., Sample 119-690C- 20X-3,119-123. 2. Archaeoglobigerina mateola n. sp., Sample 119-689B- 28X-1,76-80. 3. Archaeoglobigerina mateola n. sp., Sample 119-690C- 18X-2,99-103. Enlarged cross-sectional view of the outer wall showing microstructure of distinctive large spines that characterize this species. 4. Rugotruneana circumnodifer (Finlay), Sample 119-690C-17X- 3,119-123. 5-7. Rugotruneana circumnodifer (Finlay), Sample 119-690C- 19X-3,119-123. 8-9. Rugotruncana circumnodifer (Finlay), Sample 119- 690C-18X-5,46-49. Note the absence of a visible keel, but presence of an imperforate peripheral band. 10. Rugotruncana cirruinnodifer (Finlay), Sample 119-690C-17X-3,119-123. 11. G1obotruncane 11a petaloldea (Gandolfi), Sample 119-690C-18X-1,119-123. Scale bar for Figs. 1-2, 4-11 is 50 microns and for Fig. 3 is 10 microns.

185

Plate XVI. 1-2. Clobotruncanella havanensis (Voorvljk), Sample 119-689B-28X-3,83-87. 3-4. Abathomohalus wavaroensls (Bolli), Sample 119-690C-17X-3,119-123. 5-6. Abathomphalus Intermedlus (Bolll), Sample 119-690C-18X-5,46-49. 7-8, 12. Globotruncana subcircuranodifer (Gandolfi), Sample 119-690C-18X,CC. 9-11. Globotruncana area (Cushman), Sample 119-690C-18X-5,46-49. Scale bar for Figs. 1-12 Is 50 microns.

187 188

Plate XVI Plate XVII. Microradiographs of holotypes and several other species described in this study. 1. Hedbergella holmdelensls Olsson, Sample 119-690C-21X-4, 118-122. 2. Hedbergella monmouthesis (Olsson), Sample 119-690C-20X-5, 108-110. 3. Rugotruneana clrcumnodifer (Finlay), Sample 119-690C-18X-5,46-49. 4. Hedbergella sliteri n. sp., holotype, Sample 119-690C-18X-5,46-49. 5. Hedbergella sliterl n. sp., from Falkland Plateau DSDP Site 327, Sample 71-327-10- 3,22-24. Note the differences in ontogenetic morphology between the microradiographs of H. sliteri and those of H. holmdelensls and H. monmouthensis. 6. Archaeoelobigerlna mateola n. sp. , holotype. Sample 119-690C-20X-3,119-123. 7. Archaeoglobieerina australis n. sp., holotype, Sample 119-690C-19X-3,119-123, 8. Archaeoglohi gerlna australis n. sp. Juvenile form from DSDP Site 511, Sample 71-511-23- 4,67-69. 9. Archaeoglobigerina australis n. sp., Sample 113-690-19- 6,119-121. Edge view showing ontogenetic changes in morphology. Scale bar for Figs. 1-9 is 50 microns.

189 190

Plate XVII CHAPTER IV

PLANKTONIC FORAHINIFER BIOSTRATIGRAPHY OF UPPER CAMPANIAN-

MAESTRICHTIAN SEDIMENTS FROM ODP LEG 114, SOUTHERN SOUTH ATLANTIC

ABSTRACT

Upper Campanian through Maestrichtian planktonic foraminifers were

recovered from ODP Sites 698 and 700 on the northeast Georgia Rise in

the southern South Atlantic Ocean. The low diversity of the fauna and

the dominance by species of Heterohelix. Globigerinelloides.

Hedbergella. and Archaeoglobieerina are characteristic of Austral

Province assemblages described from other high southern latitude sites. Five species, including Globigerine1loides lmoensus.

Archaeoglobigerina australis. Archaeoelobigerina mateola. Hedbergella sliteri. and Rueotruneana ci rcumnodifer. are considered to be endemic to the Austral Province.

Biostratlgraphic ranges of provincial and cosmopolitan taxa are correlated with those in other southern South Atlantic deep sea sites and age determinations for several datum events are discussed.

Diversity plots show a significant increase in total and keeled species diversity during the late Maestrichtian, as was observed at

ODP Sites 689 and 690 (Maud Rise). This corresponds with an influx of several Tethyan marker species, suggesting a poleward expansion of the

Tethyan Province during the late Maestrichtian. However, no

191 192

corroborating evidence for a warming event has been observed from

calcareous nannoplankton distributions or oxygen isotope

paleotemperature studies of the high latitude South Atlantic region.

INTRODUCTION

Two of seven sites drilled during Ocean Drilling Program (ODP) Leg

114 penetrated chalk and limestone sediments yielding Upper Cretaceous

foraminifers. Well preserved Maestrichtian assemblages were obtained

from a chalk sequence drilled at Hole 698A, which is located near the

eastern edge of the Northeast Georgia Rise (51°28'S, 33°6'U) at a water depth of 2128 m (Figs. 29, 30). Hole 700B is located about 85 km to

the east of Hole 698A on the northeastern slope of the Northeast

Georgia Rise (51°32' S, 30°17'W) at 3611 m water depth (Figs. 29, 30).

Moderately to poorly preserved foraminifer assemblages, ranging from

Santonian (late Turonian?) to late Maestrichtian in age, were recovered from a thick limestone section at this deeper water site.

Planktonic foraminifers from the upper Campanian-Maestrichtian sections of both holes were analyzed for comparison of their blostratigraphic and biogeographic distributions with other assemblages reported from the high latitude South Atlantic region.

Campanian-Maestrichtian foraminifers have been previously recovered from several sites in the southern South Atlantic and

Weddell Sea region (Fig. 29). These include Deep Sea Drilling Program

(DSDP) Sites 327 and 511 on the Falkland Plateau (Siiter, 1977;

Krasheninnikov and Basov, 1983), the James Ross Island region of the northeastern Antarctic Peninsula (Huber, 1988), and ODP Sites 689 and 4

193 Figure 29. Figure 30. Vertically exaggerated cross-section of the southern South Atlantic sea floor at about 51°S showing the locations of ODP Sites 698 and 700.

195 1000

I 3000 700

3000 1000 k»

Figure 30.

O' 197

690 on the Maud Rise (Chapter III). Planktonic foraminifer

assemblages from all of these sites are characterized by 1) low

taxonomic diversity, 2) dominance by long-ranging globulose species,

and 3) rare occurrence of zonal markers used in low latitude zonalschemes, particularly forms bearing peripheral keels. The distinctive extra-tropical character of these high latitude assemblages was the basis for their inclusion in the Austral Province

(Sliter, 1977; Krasheninnikov and Basov, 1983; Huber, 1988; Chapter

III).

No planktonic foraminifers were recognized as being endemic to the

Austral Province prior to study of the Maud Rise assemblages and systematic comparison with assemblages from the Falkland Plateau and the James Ross Island region (Chapters II, III). As a result of the taxonomic comparisons, three species were proposed as new and five species were suggested to occur only within the high southern latitude regions of the Austral Province, The total stratigraphic ranges of these species were uncertain, however, because of hiatuses and incomplete core recovery at the Falkland Plateau and non-recovery of pre-Maestrlchtian sediments at the Maud Rise (Fig. 31).

Because most of the Campanian was not recovered during Leg 114

(Fig. 31), resolution of the lowest appearance datums for several of the Austral Province species must await recovery of a more complete

Campanian section from the high southern latitudes. Nevertheless,

Site 700 does provide a more continuous upper Campanian to

Maestrlchtian transition than that recovered at the other southern

South Atlantic sites. Documentation of foraminifer distributions Figure 31. Correlation of Santonian through Maestrlchtian deep sea sites in the southern South Atlantic based on recognition of the Globigerinelloides imoensus Zone, Globotruncanella havanensis Zone, and Abathomohalus mavaroensis Zone, as defined in Chapter III.

198 SOUTHEHN SOUTH ATLANTIC Him

7 0 0 6 680C 3 2 7 A

2128 2 4 1 0 W s M O a p t h (m) Top Cutacoout 330.7 233.4 1 9 6 .0 1 1 6 .0 (mbaf)

3 9 20 DU

4 0

4 3 24 6 0 22 HL L

- 8 0

100 ■£

4 9

30 - 1 2 0 £

3 2

- 1 4 0

1 6 0 35

ISO

200

m 4 0

220

Figure 31, 200 within this time frame at Sites 698 and 700 enables refinement of a new zonal scheme proposed for the high southern latitudes and demonstrates regional synchroneity of changes in species diversity and composition. These results will provide a better understanding of the paleoenvironmental evolution of this region.

METHOD OF STUDY

Samples used in this study are from Cores 114-698A-16R through -

20R (137 to 181 meters below sea floor), and from Cores 114-700B-37R through -32R (330.7 to 470 mbsf). One sample per section was obtained from each available core. The samples were disaggregated in water, stirred over a warm hotplate, ultrasonically cleaned, and then sieved through a 63 micron screen. Numerical abundance counts of 300 specimens were performed for the >130 and <150 micron size fractions of samples yielding well preserved foraminifers. Counts of 300 specimens from only the >63 micron size fraction were done on all moderately and some poorly preserved samples. Specimens found after the initial 300 specimen count are denoted by an X on Tables 3 and 4.

Relative abundances of foraminifers and other biogenic constituents were determined for poorly preserved samples based on grain counts of the >63 micron size fraction from one field of view at low magnification. Relative abundance values for each species or microfossil constituent are as follows: abundant - >26%, common - 16-

25%, rare - <5%. Total foraminifer abundances ranked as rare reflect predominance of indurated grain aggregegates rather than dominance of other biogenic constituents. 201

Preservation of the Leg 114 Cretaceous foraminifers ranges from

good to very poor (Tables 3, 4). Assemblages designated as having

good (G) preservation show little or no test fragmentation, etching,

or recrystallization. A moderate (M) preservation rating is assigned

to assemblages with fragmented, strongly etched tests that are

infilled with sediment, and/or overgrown with secondary calcite, Poor

(P) preservation ratings are assigned to assemblages that were more severely fragmented, etched, and/or overgrown and difficult to

identify to the species level. Very poor (VP) preservation was noted for assemblages with very few or no identifiable specimens.

The zonal scheme applied in this study was previously proposed for the high southern latitudes based on Maestrichtian foraminifer distributions at Maud Rise ODP Sites 689 and 690 and their correlation with sections recovered from DSDP Sites 327 and 511 (Chapter III).

The following three planktonic foraminifer zones are recognized: 1) the Abathomphalus mavaroensis Total Range Zone (upper Maestrichtian),

2) the Globotruncanella havanensls Interval Zone (lower to middle

Maestrichtian), and 3) the Globigerlnelloides impensus Total Range

Zone (upper Campanian through lower Maestrichtian).

Core sample notation follows the standard ODP format, listing the leg number, hole designation, core number and coring method, section number, and the downcore centimeter interval.

BIOSTRATIGRAPHY

HOLE 698A

Continuous rotary drilling at Hole 698A penetrated 72.5 m of Figure 32. ODP Hole 698 lithostratigraphy, stratigraphic ranges of selected planktonic foraminifer and calcareous nannoplankton species, total and keeled planktonic foraminifer diversity plots, and planktonic/benthic foraminifer ratio plots. Calcareous nannoplankton plots based on data from Crux (in Ciesielski et al., in press).

202 203

BIOSTRATIGRAPHIC RANGES OF PUKNKTONIC TOTAL cc>- SELECTED SPECIES, UJ U I UJ DIVERSITY FORAMINIFER 9 ODP SITE 698 § s i §8Iu Calc. (No. of Spacm ) E Ptartoone Forvrinrfarv Nanno.

1 4 120 .3 3 X 15 I 130

16 140 I I I I l 3 O 1 S I 5 9 a 150

i f f ! i f f i i f f 160 rXT f f i i f f i f f

170 r f f i f f i f f i f f

180 21

• Total C l i d > Kaated E d Nannofoaail Chart Cha* Umaatona

Figure 32. 204

Cretaceous sediment, but only 13,2 m of section (18.2%) were recovered

(Fig. 32). The Cretaceous-Tertiary boundary was determined to occur in an unrecovered interval between the core catcher of Core 114-698A-

13R and the top of Core 114-698A-14R, at about 118 meters below sea floor (mbsf) (Ciesielski et al., in press). Occurrence of chert stringers within the Cretaceous sequence hampered drilling effortsand probably caused zero recovery in Cores 114-698A-18R -19R, and -22R.

Drilling terminated at 237 mbsf after 27 m of basalt were recovered.

The Cretaceous sequence was subdivided into two lithologic units and five subunits. The upper 28 ra, from Cores 114-698A-14R though -

16R, are included in Subunit lib, which consists of a moderately bioturbated nannofossil chalk with sporadic intercalations of foraminifer-bearing nannofossil ooze and chert. Subunit lie comprises

Cores 114-698A-17R through -21R and ranges from 146.5 to 190.5 mbsf.

This is a faintly to moderately bioturbated, fine-grained limestone with chert intercalations increasing in number towards the bottom of the subunit. Minor constituents in Subunit lib include volcanic ash, radiolarians, diatom fragments, zeolites, and clay (Ciesielski et al., in press). The three subunits comprising Unit III include sandy muds

(Subunit Ilia), aphanitic basalt (Subunit Illb), and hematitic claystones (Subunit IIIc). Nannofossils found in Subunit Ilia are the only biogenic constituents reported for Unit III, and these are considered to be reworked (Ciesielski et al., in press).

A total of five samples from Hole 698A were available for this study. Numerical and relative abundance counts of foraminifers are portrayed in Table 3, together with foraminifer preservation ratings Table 3, Numerical abundance counts of planktonic foraminifers (totalling 300 specimens) and other biogenic constituents for Hole 698A. X — species found after to first 300 specimen counts; A — abundant, F — few and R - rare occurrence in the sieved residues; G — Good and P - poor preservation.

205 Table 3.

■ •

ODP ft z 0 o

ft w ft ft 1ft o X f t 8 2 } HOLE a Ml 8 8 ft Q u tn ft *4 X tft X — z 0 Ikl Ift if> c 1rcuanodIfir — • ft u M 9 # z 8 8 X 8 c c in ft ft tn 698A £ « «c 8 8 w 1. z 0 u o ut W 8 ■It tn Ifi 8 9 • • c f t ft. ft 111 3 m ft 3 ft f t X a Z 0 8 0 9 9 9 k u ■ L k i . X z 8 f t 8 0 a * 8 • ft ft ft ft • 0 8 o j £ ft 0 X X X ft X Ml 8 0 U £ £ 0 £ £ ft a a l> f t O « i t 9 0 x 8 8 J X O f t 0 ft ft Ml O O 8 a X 8 I X II X Globtgvrintllaidat •ubcarinatuc U 1 ft ft U in O 8

16-1,67-71 > 7 3 49 . * 30 27 9 24 , 6 11 X X X 69 C 6 137.67

< 26 61 4 3 81 SB 2 1 , 2 2 X • X 38 AS

16-2*67-71 >7 4 27 . B 28 34 42 . 13 27 9 • X X 3B A B 1 3 9 .1 7

<30 73 9 3 69 57 4 2 . 6 2 1 X X 40 A 6

17-1,29-32 > 130 28 . 29 - 1 9 1 5 -•- ■ 97 A S 14678

< 41 73 12 1 60 33 X , X X . X 77 *- ■ • A 6 R MAESTRICHTIAN

17 -2t 12-16 > 123 60 . 34 - * 8 6 X 2 3 2 42 A 6 R 1 4 8 .1 2

< 14 59 28 1 99 37 1 X 2 2 6 33 A B R

20-1,16-10 t X 33 t X 22 IB . 223 R P F 17516

> - gruiarthan 150 micron friction <**«» than 150 micron fraction t - g ra m thm 63 micron fraction 207 and relative abundance rankings for other biogenic constituents. The stratigraphic distribution of several important planktonic foraminifers is shown in Fig. 32, together with plots of total and keeled species diversity and planktonic/benthic ratios. Calcareous nannoplanktonic distributions of two important species, based on data from Crux (in Ciesielski et al., in press).

Preservation

Foraminifers from Cores 114-698A-16R and -17R show evidence of minor test recrystallization, but overall preservation is good. This permitted numerical abundance counts for both the >150 and <150 micron size fractions (300 specimens each), and reliable correlation with numerical abundance counts of Maud Rise Site 689 and 690 foraminifers.

Sample 114-698A-20R-1,16 -18 is too poorly preserved to allow specimen counts of the >150 micron size fraction and, therefore, counts were only performed for the >63 micron size fraction (Table 3).

Foraminifer Distributions

Samples 114-698A-16R-1,67-71 and -2,67-71 yield the planktonic foraminifer Abathomphalus mavaroensis (Bolli), enabling correlation with the upper Maestrichtian Abathomphalus mavaroensis Zone used in low latitude zonal schemes (e.g., Caron, 1985). This zone was also recognized at Maud Rise Sites 689 and 690 (Fig. 31). Other important marker species in the Core 114-700B-16R samples include

Globieerinelloides subcarlnatus (BrOnnimann), Globotruncanella petaloidea (Gandolfi), Rugotruneana circumnodifer (Finlay), and 208

G1obo t rune ana area (Cushman). The distribution of G. petaloidea and

£. subcarinatus at Site 698 and Maud Rise Sites 689 and 690 (Chapter

III) is limited to the A. mavaroensis Zone, but both species have been reported from lower through upper Maestrichtian sediments in tropical to subtropical regions (e.g., Pessagno, 1967; Caron, 1985). Maximum diversity of 13 species also occurs within this zone (Fig. 32).

The upper Maestrichtian calcareous nannoplankton marker species

Nephrolithus freouens (Gorka) was reported by Crux (In Ciesielski et al., in press) to range from Core 114-698A-14R through Core 114-698A-

16R at Hole 698A. However, Crux attributed the occurrence of this species in the core catcher of Core 114-698A-16R to downhole contamination because of its co-occurrence with Reinhardtites levis

Sissingh and Prins (Fig. 32). The latter calcareous nannoplankton species v,as a reported last appearance datum (LAD) of late middle

Maestrichtian (Sissingh, 1977). Wise (in Barker et al,, in press) also found overlap in the ranges of N. freauens and g. levis. but this was attributed to a diachronous (earlier) first appearance of g. freouens in high latitude regions. Occurrence of several specimens of

4- mavaroensis in 300 specimen counts for Samples 114-698A-16R-1,67-71 and -16R-2,67-71 (Table 3), and their co-occurrence with £. petaloidea and G. subcarinatus. suggests that their presence is not due to reworking. Therefore, upper Maestrichtian sediments are determined to range at least to the base of Section 114-698A-16R-2.

Large forms of R. circumnodifer occur in both samples from Core

114-698A-16R and smaller forms of this species first appear in Sample

114-698A-17R-2,12-16 (PI. XIX, Figs. 4-10). R. ci rcumnodifer shows a 209 similar stratigraphic distribution at the Maud Rise, ranging from the upper Globotruncanella havanensls Zone through the mavaroensis Zone

(late middle through late Maestrichtian). Occurrence of Hedbercella sliteri n. sp. in Cores 114-698A-16R and -17R is also consistent with the range of this species at the Falkland Plateau and the Maud Rise

(see Chapter III). G. area is reported to range from the latest

Santonian through late Maestrichtian (Caron, 1985), but this species was not found below the mavaroensis Zone at Site 698. Occurrence of Guembelitria cretacea Cushman in Sample 114-698A-17R-1,28-32 is consistent with its middle to upper Maestrichtian range reported from the Maud Rise (Chapter III) and other Cretaceous localities (Caron,

1985). Absence of the upper Maestrichtian marker species in Core 114-

698A-17R together with the presence of g. circuranodifer suggest a middle Maestrichtian age for Core 114-698A-17R..

Numerical abundance counts of the >150 micron size fractions from

Core 114-698A-16R and -17R samples (Table 3) show that

Archaeoelobigerina australis n. sp. is the dominant species in the coarser sediment residues. This is also the most common taxon in

Maestrichtian sediments from the Maud Rise and the Falkland Plateau

(Chapter III). Occurrence of A. australis. together with

Archaeoglobigerina mateola n. sp. and Hedbereella sliteri. at Site 698 demonstrates a broader regional distribution within the high southern latitudes than was hitherto known.

Poor foraminifer preservation and absence of age diagnostic species preclude an accurate age determination for Sample 114-698A-

20R,16-18. Globieerine1loides multispinatus (Lalicker), Heterohelix 210

globulosa (Ehrenberg), and Heterohellx pulchra (Brotzen) are the

dominant planktonic foraminifer species in this sample. All have long

stratigraphic ranges in the Upper Cretaceous. The presence of

Archaeoglobigerina australis n. sp., Hedbergella monmouthensis

(Olsson), and Heterohelix glabrans (Cushman), which are very rare,

suggests a late Campanian-Maestrichtian age. Absence of

Globigerinelloides impensus Siiter from this sample indicates an age

no older than early Maestrichtian, Persistent occurrence of the

latter species, which is the nominal taxon of the upper Campanian-

lower Maestrichtian Globigerinelloides impensus Zone, at Site 700

suggests that its absence at Site 698 is not an artifact of poor

preservation.

The high relative abundance of benthic foraminifers (Fig. 32;

Table 3) and strong etching of foraminifer tests in Sample 11A-698A-

20R-1,16-18 suggest strongly corrosive conditions, perhaps due to

deposition below the foraminifer lysocline.

HOLE 700B

A thick (158.3 m) sequence of Santonian (late Turonian?) through

Maestrichtian limestone was continuously cored with the rotary bit from 330.7 to A89 mbsf at Hole 700B (Fig. 33), Recovery of the

Cretaceous sediments, averaging 66.8% (105.7 m), was much better at this site than in Hole 698A, probably due to the near absence of chert interbeds. The Cretaceous-Tertiary boundary was not recovered at Hole

700B, as Cretaceous calcareous nannoplankton were reported from the top of Core 114-70QB-37R and Tertiary species were found in the core Figure 33. ODP Hole 700B lithostratigraphy, magnetostratigraphy, stratlgraphic ranges of selected planktonic foraminifer and calcareous nannoplankton species, total and keeled planktonic foraminifer diversity plots and planktonic/benthic foraminifer ratio plots. Calcareous nannoplankton distributions based on data from Crux (in Ciesielski et al., in press).

211 212

StOSTRATIGRAPHIC RANGES OF SELECTED PLANKTONIC ill U l Is SPECIES, OOP SITE 700 CMVERSITT S 5 ie- ^ ts* Cafcaroout (No. oI Spada*} Pltuttonk; Foramlniw* Manno- I » a »o 7* purtdon _l— I_U 1 3 7 V

340

3 5 0

e 360 I j > 41 1 z 370

300 43

3 9 0

I 4 5 400

4 1 0

4 7

§ 4 2 0

4 3 0 UtMMona

Clay-bMring Tout fcnaatona

Figure 33. catcher of Core 114-700B-36R (Crux, ,in Ciesielski et al., in press).

Drilling terminated at Hole 700B as a result of premature bit release after Core 114-700B-54R was retrieved.

The limestone sequence cored at Hole 700B extends from 319 mbsf to the bottom of the hole. This was included in lithologic Unit V, which was subdivided into three subunits using the degree of lithologic homogeneity and differences in the amount and type of non-biogenic constituents. Subunit Va (319 to 359 mbsf) consists predominantly of a strongly bioturbated, homogeneous nannofossil-bearing micritic limestone with occasional horizons of clay-bearing limestone. This is underlain by a faintly to moderately bioturbated, clay-bearing limestone, which comprises Subunit Vb (359 to 441.5 mbsf). Subunit Vc

(41.5-489 mbsf) is differentiated from the overlying sequence only by the presence of ash-bearing zeolitic clay horizons and a volcanic ash component that increases gradually downhole.

Preservation

Preservation of Cretaceous foraminifers at Site 700 ranges from moderate to very poor (Table 4). All specimens show evidence of test recrystallization and many samples yield foraminifer tests completely infilled with calcite. Several samples from Cores 114-700B-39R and -

40R show evidence of their deposition below the foraminifer lysocline.

Samples 114-700B-39R-2,72-76, -39R-4,72-76, and -40R-1,68-72 have much lower planktonic/benthic ratios than the other Cretaceous samples

(Fig. 33) and yield foraminifers with moderately to strongly etched tests. Foraminifer test dissolution was also apparent in the other Table 4. Numerical and relative abundance counts of planktonic foraminifers and other biogenic constituents for ODP Hole 700B. C — common abundance; M — moderate preservation; see Table 3 for key to other symbol abbreviations.

214 LTl IN » i n 4A a a ** 4 09-9C C - t f t LSitr * 4 4A a a a a 4 a a 111-40! f t - t f t £0 9 0 a * a 4A a a • ■ a a a a 111-4QI c - t f t a m a a a 8A a a * a a a * 4 a (11*401 Z - t f t £0ES» a a 4A a a * 4 a * a 111-401 I - t f t £ a o o 8 - a a a a * 4 a a a a 1 9 - 4C 9-Oft £ iO Stt « a a 4 3 a * * 4 a 4 A a a 4 a I9-4C G -B ft > f 85 £J* M * 4* a a * ■ L a E 9 - K ft-Oft z c 90 9 0 H a a JA a a 4 a a a * a a a 09* 9C G -B ft i w « » a a 4A a a " £ a * a ** a ft9-09 Z-Bft 0 1 0 9 a a 4A a a • • a 4 a a a ft9-09 l-B ft »£!► a a * a a 3 ct * I 9 zt 9Zt 19 4Z i ftZ cz 9 l * Z l C- 4ft ci 0 1 1 9 a a * a a 3 9 01 41 ftZ OCI 49 OZ 9 91 4Z-CZ ft-4ft 1 0 9 1 9 a a * 4 4A a a " ’ a a a a a Z G -9Z Z- 4ft 1 £ ttl9 a a a a dA a a '* a a 4 * I t - £ 8 I-Zft s 91 £09 j ' a a 3 i * R * cz It! 9ft V it 9Z1-ftZt E- 9ft WS09 a a a a a 3 9 I ft ft * E t 49 *4 Z ftOI e o i - t t Z-9ft 8£ 909 a a a a a 3 9 X I ■ t * Oft Zt GC 4 i 9 L 8Z1*ftZl t-9ft *»08C a a ■ * aA a a * a a a a c t - f t c t Z-Cft o n e a * dA a a * * * a z e i - G G i l-Cft z r n c a a a a a a ' * a a a a a 14-4t l-ftft a jsc a a a A a a 8C 9 C l * ftC Cft 9 C t B CC-tft 4-Gft w is e a a a d w 3 t ¥ ft CC * c z GC in i ft ftftt-Oftl 9-Eft 09 OK a a a a a U * (Z * ftZ Zfi CGI t ftftl-Oftl C-tft 00 OK a a a 4 a 4 8 4 zb * IE 91 48 i 9 f tf tt- O f tl ft-Cft 1 0*iSC a a a A M 4 ££ * Z9 I * Zft tz C t i Z ftftf-Oftl C-Eft d S K a 3 a A a a 99 * OZ t 9C o t It X ■ tftl-£Ct Z*Cft £C9«c a a d K 3 Cl 4 £ ft 4E ftft zee 9 ' I41-4EI t-Cft S8KC a A U 3 cz * rt ■ * * IfH Cft M C9 4 4C -C C G -C ft K S l t a a a a a 9C 9 19 E * CC Cft IB Cl * 4 C -S C Z -Z ft 9 ft o r u e a a a i u V Cl X 9 ftC 4 tz C9 ZOI t ftft-Oft 1-Zft a 1 o r iK a a a w a rz ' Cl 4 4Z 4 1 OCI B1 * ftft-Oft ft-(ft 5 1 09 IK a 3 It 3 CI E ftt 4 la 9ft 91 IZ ftft-Oft G - l f t i I o t s k a a A u V tz 9 9 IZ * 8 4 4Z SOI ftl * ftft-Oft Z - l f t z 1 09 9K a a a u a ►c 9 a ' BC 09 14 OZ * ftft-Oft 1-lft 81 IK a a a It V 4 I I e c * tz 08 91 B Z4-B9 G-O ft 88 « C a a a a u a tft I GC • 4G at tft t Z4-B9 ft-Oft 59 8 0 a a a H V IZ • Cft * o z 99 0 9 4 4 4 - S t C -O ft 8 1 8 0 a a 3 a 3 S9Z 1 L z zt C X Z4-B9 1-Oft 8 1 0 0 a a 9 u 3 izi C l IZ * Zft OZ cr ft 94*Z£ ft-4C * *8 89f a a a a N V £l % tz tz Clt C9 1C IZ 94-Z4 G -4 C 1 *t£9C a a 4 M a G*1 * ftt Z1 * 3Z IE 41 94-C4 Z-4C j 1 99 5K a a ' A W a OC C c z * IZ1 Cft Ct 9 04*99 t - t c 1 oitre a a a M a (G K X 01 t * za f tt t f t t * f t t - 0 4 C *4G Ofltt a H 3 CC Cl « t c 4CI 19 o c ftt-06 1-4G * 4 0 w it 4 ft 4 X a 8 > 1 X * X 8 X J n ft 0 f ft s n » a 0 ft « ft ■ ft fl ft ft ft O 4 X r 4 ft X % D 0 n 4 ft 7 ft 0 ft 0 fi 0 N * g ft > • •4 9 r V 7 ft ft ft 9 9 ft 9 9 T ft > 0 * ft t X t £ f « ft ft a ft T ft a ft a r <* 4 9 ft ■* 8 ft ft ■t i ft i ft * m m II • ft » 4 X E o « ft 0 7 « 0 « # 7 a fl ft S X * c e ft ft ft ft ■ C 8 — n C ft 4 ft ft 3 3 BOOZ l ft ft ft • ft ft 0 n 3 a ft 3 n Q 3 X 4 ft ft ft ft •• • 9 • ft ft • ft ft « ft ft 3 ft 3 •• «• c 7 • ft « 0 ft ft 9 ft C a ft fl 9 1 • 3 310H * t ft 1 p- t ft ft ft 9 n ft 7 Q ft ft ft 7 3 3 ft i • ft ft ft t 0 ft ft 3 ft ft 3 •4 ft ft ft ■ • 7 3 ft ft ft ft ft ft 3 C ft C ft dQO < 4 3 ft 3 ft ft ft ft ft < ■ ft 0 ft i 3 ft ft ft ft ft N ft C ft ft 3 • ft

■fr aiQBI 216

samples examined from Cores 114-700B-39R and -40R, as well as in

Sample 114-700B-42R-2,35 - 39. Numerical abundance counts were not

performed separately for sample splits from the >150 and <150 micron

size fractions because of the insufficient preservation. Counts of

300 specimens were made on the >63 micron fraction of all moderately

preserved and some poorly preserved foraminifer samples (Table 4).

Foraminifer Distributions

Planktonic foraminifer distributions in the Maestrichtian sequence of Site 700 (Table 4) are identical to those from Site 698 and to distributions reported from Maud Rise Sites 689 and 690 (Chapter III).

The only apparent difference is the relatively low numerical abundance value determined for Archaeoglobigerina australis n. sp. Much higher values were obtained at the other southern South Atlantic sites because 1) the size fraction in which A. australis is most abundant

(>150 microns) was not separated and counted at Site 700, and 2) preservation is much better at the other sites so that test breakage by harsh sample preparation was avoided. Other species considered as endemic to the Austral Province, including Archaeoglobigerina mateola.

Hedbergella sliteri. Rugotruneana circumnodifer and Globigerinelloides imnensus. also occur in low abundances at Site 700. Dominant species throughout the upper Campanian-Maestrichtian sequence at Site 700 include Heterohelix globulosa. Heterohelix pulchra. and

Globigerinelloides multisolnatus.

Samples 114-700B-37R-1,90-94 through -39-4,72-76 (331.6 to 350.2 mbsf) are correlated with the Abathomphalus mavaroensis Zone and are 217

designated as late Maestrichtian in age based on the distribution of

the nominal taxon (Fig. 33; Table 4). G. petaloidea and Q.

subcarinatus also range within this zone. Other significant species

in this interval are Heterohelix glabrans. Rugotruncana clrcumnodifer

(Finlay), and Globotruncana area (Cushman). The late Maestrichtian age assignment is consistent with the distribution of the calcareous nannoplankton species Nephrolithus freouens. which ranges from 353 mbsf to the top of the Cretaceous sequence (Fig. 33).

The early to middle Maestrichtian Globotruncanella havanensis Zone

is recognized from Samples 114-700B-40R-1,68-72 through -43R-2,137-141

(355.2 to 385.9 mbsf) by the sporadic occurrence of £. havanensis and the absence of Globigerinelloides impensus (Table 2). First occurrences of Rueotruncana circumnodifer in Sample 114-700B-40R-4.68-

72, Guembelltria cretacea in Sample 114-700B-40-3,95-99, and

Hedbereella sliteri n. sp. in Sample 114-700B-40R-5,68-72 indicate a middle Maestrichtian age based on correlation with their distributions at Maud Rise Sites 689 and 690 (Chapter III) . This age assignment is supported by the LAD of the calcareous nannoplankton species

Relnhardtltes levis at 350.5 mbsf (Fig. 33), which has been dated paleomagnetically at 71.50 Ma (uppermost middle Maestrichtian) (Kent and Gradstein, 1985). Absence of Globotruncana area and all other keeled species from the lower part of the Globotruncana havanensis

Zone is consistent with the Maud Rise foraminifer distributions.

No foraminifer datum events used in low latitude zonal schemes can be recognized In the upper Campanian through middle Maestrichtian sediments below the ft. mavaroensis Zone at Site 700. The 218

Campanian/Maestrlchtian boundary was placed at 408.40 inbsf based on

the LAD of the calcareous nannoplankton species Eiffellthus eximius

(Stover) at this level (Fig. 33) (Crux, in Ciesielski et al., in press). A blostratigraphic event that can be correlated among several high latitude South Atlantic sites is the LAD of GlobIgerlnelloides

impensus Sliter, which delimits the zonal boundary between the £. havanensis Zone and the £. impensus Zone. At Site 700, this datum occurs within the lower Maestrichtian Sample 114*700B-43R-3,140-144

(387.40 mbsf), 21 m above the LAD of E. eximius (Fig. 33). The earliest evolutionary appearance of £. impensus was probably not recorded at any of the southern South Atlantic drilling sites, including Hole 700B, because stratigraphic disconformities truncate its lower stratigraphic range (Fig. 31). Nevertheless, the first occurrence of £. impensus in Section 114-700B-49R-4, which was assigned a late Campanian age based on the range of the calcareous nannoplankton Eiffelithus eximius (Stover) (Crux, in Ciesielski et al., in press), is consistent with its first appearance in upper

Campanian sediments at the Falkland Plateau and Maud Rise (Sliter,

1977; Krashennnikov and Basov, 1983; Chapter III).

Evidence for a stratigraphic hiatus between Cores 114-700B-49R and

114-700B-50R (Fig. 31) is based on occurrence of early Campanian to

Santonian calcareous nannoplankton In the latter core (Crux, in

Ciesielski et al., in press). Foraminifers from samples below Core

114-700B-49R will discussed by Premoli Silva (In prep.). 219

Diversity Trends

Taxonomic diversity values are highest within the Abathomohalus

mavaroensls Zone, which yields a maximum of 14 planktonic foraminifer

species (Fig. 33). Total diversity diminishes below this zone,

ranging from between five and nine species in the Globotruncanella

havanensis Zone and between one and nine species in the

Clobigerinelloides impensus Zone. Diversity values in the lower part

of the sequence are biased by poor preservation quality, and thus do

not reflect a regionally significant trend. Nevertheless,

preservation is not considered a factor controlling diversity for

samples above Section 114-700B-43R-4, all of which have moderate preservation quality. Diminishing diversity values with increasing depth in the £. havanensis Zone were also observed at Maud Rise Sites

689 and 690 (Chapter III).

Keeled planktonic diversity is highest within the &. mavaroensls

Zone, with a maximum of three double keeled species (&. mavaroensls.

G. area■ and £. circmnnodifer^ occurring in several Core 114-700B-39R samples. Keeled mophotypes are nearly absent from the £. havanensis

Zone and a single species, Globotruncana linneiana (d'Orbigny), sporadically occurs in rare abundance within the Campanian section of the G . impensus Zone.

Magnetochronologic Correlation

Several discrepancies in correlation of planktonic foraminifer and calcareous nannoplankton datums with the magnetic reversal stratigraphy, determined by Clement (1q Ciesielski et al., in press). 220

are apparent at Site 700. The first appearance datums (FAD) of the

upper Maestrichtian species mavaroensls and N. frequens occur

within an interval designated by Clement as Chron 30R (Fig. 33).

However, the magnetostratigraphy of the Cretaceous sequence at Maud

Rise Site 690 (Chapter III) and the magnetostratigraphy of Kent and

Gradstein (1985) and Honechi and Thierstein (1985) show that the FAD

of these species occurs in Chron 31R. In addition, the LAD of the

Campanian/Maestrichtian boundary marker £. eximius occurs in sediments

assigned to Chron 32R at Site 700, but the extinction of this species

was found to be within Chron 33N by Kent and Gradstein (1985) and

Monechi and Thierstein (1985). These discrepancies could be resolved

if a longer hiatus, spanning from Chron 29R through most of Chron 30N

(about 1.0 m.y.), is recognized at the top of the Cretaceous sequence

at Site 700. Reinterpretation of the Site 700 magnetic reversal

stratigraphy is crucial for accurate inter- and extra-regional correlation of the high latitude Campanian-Maestrichtian sequences.

DISCUSSION

The upper Campanian-Maestrichtian planktonic foraminifer assemblages from Holes 698A and 700B are identical in species composition to Austral Province assemblages described from the

Falkland Plateau (Sliter, 1977; Krasheninnikov and Basov, 1983) and the Maud Rise (Chapter III). These are characterized by low taxonomic diversity and dominance by several species of Heterohelix and by

Globjgerinelloides. Hedbergella. and Archaeogloblgerina. Numerous species that are common components of Tethyan assemblages, 221

particularly those of the Globotruncanacea, are completely absent from

the southern South Atlantic assemblages.

Several planktonic foraminifer species were previously suggested

to be endemic to the Austral Province (Chapter III) . These include

Globjgerinelloides impensus. Hedbergella sliteri. Archaeoglobleerlna

australis. Archaeoglobieerlna mateola. and Ruyotruneana clrcumnodifer.

Occurrence of all of these species in the upper Campanian-

Maestrichtian sequences at Sites 698 and 700 enables a more accurate

determination of their stratigraphic and paleobiogeographic distributions. A summary of the high southern latitude occurrences of

these provincial species and their known stratigraphic ranges is presented in Table 5. Austral Province locations where each species is present are portrayed on a paleogeographic reconstruction for 80 Ma

(Fig, 34). Predominance of low diversity planktonic foraminifer assemblages and occurrence of species endemic to the Austral Province in the southern Indian Ocean (ODP Site 750; P. Quilty, pers. comm.), the Tasman Sea (DSDP Site 208; Webb, 1973), and New Zealand (Webb,

1971) demonstrates the circum-Antarctic biogeographic range of the

Austral Province assemblages. These paleobiogeographic distributions are proposed to record the presence of circum-Antarctic marine passages and divergent oceanic currents at the northern limit of the

Austral Province (see Chapter V for further discussion).

Stratigraphic changes in planktonic foraminifer species diversity at Holes 698A and 700B (Figs. 32, 33) are similar to those at Maud

Rise Sites 689 and 690 (Chapter III). Maximum values of keeled species diversity and total species diversity are within the lower &. 222

Table 5. Site locations and age ranges for planktonic foraminifer species that are endemic to the Austral Province.

ENDEMIC SPECIES SITES OF OCCURRENCE AGE RANGE

Globigerinelloides impensusFalkland Plateau late Campanian Maud Rise early Maestrichtian Northeast Georgia Rise late Campanian-early Maestnchtian Kerguelen Plateau late Campanian

HedbergeUa sliteri Falkland Plateau early Maestnchtian Maud Rise eariy-late Maestnchtian Northeast Georgia Rise middle-late Maestrichtian James Ross Island region eariy-late Maestrichtian Lord Howe Rise middle-late Maestrichtian

Archaeoglobigerina australisFalkland Plateau late Campanian-eariy Maestrichtian Maud Rise eariy-late Maestrichtian Northeast Georgia Rise late Campanian-late Maestrichtian James Ross Island region early-middle Maestrichtian

Archaeoglobigerina mateolaMaud Rise eariy-late Maestrichtian Northeast Georgia Rise eariy-late Maestrichtian James Ross Island region early Maestrichtian

Rugotruncana circumnodiferMaud Rise middle-late Maestrichtian Northeast Georgia Rise middle-late Maestrichtian James Roas Island region early Maestrichtian 223

AUSTRAL PROVINCE SPECIES

<> QloblQmrbfttoMai knpantut

-O Hadbargmlla rlltarl

O Arc/la«oslo6f0*rfna auttrmll*

•Hf Arebaaogloblgarlnm matwola

Figure 34. Paleogeographlc reconstruction map showing the circunt- Antarctic distribution of upper Campanian-Maestrichtian planktonic foraminifer species that are endemic to the Austral Province. Continental distributions are based on a reconstruction for 80 Ma by Smith et al. (1981). The paleogeography of South America and Africa are from a reconstruction of Barron (1987) for the early Maestrichtian. The basis for reconstruction of Antarctic land-sea distributions is discussed in Chapter V.zone at the Falkland Plateau and Maud Rise (Sliter, 1977; Krasheninnikov and Basov, 1983; Chapter III). Globotruncana linneiana is the only bicarinate species found within the lower £. lnroensus Zone, sporadically occurring at Site 700 in rare abundance (Table 4). Total planktonic species diversity is very low within this zone at all high southern latitude sites. 224 mavaroensls Zone at all southern South Atlantic sites. In addition, keeled specimens of R. circumnodifer and G. area attained their largest diameters (up to 600 microns) within this zone. The stratigraphic increase in test size also occurred at the Maud Rise sites.

Double keeled planktonic morphotypes are completely absent from the upper Globleerinelloides impensus Zone at Site 700 (between Cores

114-700C-41R and -46R) and do not occur in any samples within thatzone at the Falkland Plateau and Maud Rise (Sliter, 1977; Krasheninnikov and Basov, 1983; Chapter III). Globotruncana llnneiana is the only bicarinate species within the lower G. impensus Zone, sporadically occurring at Site 700 in rare abundance (Table 4). Total planktonic species diversity is very low within this zone at all high southern latitude sites.

Conventional paleobiogeographic models for Upper Cretaceous planktonic foraminifers (e.g., Douglas, 1969; Scheibnerova, 1973;

Sliter, 1977; Krasheninnikov and Basov, 1983, 1987) would suggest that the late first appearances and diversification of keeled morphotypes during the late Maestrichtian at the high latitude sites was caused by expansion of a warm, subtropical water mass into the high southern latitude region. However, such a warming event in the late

Maestrichtian has not been recognized in oxygen isotope paleotemperature studies of belemnites (e.g., Stevens and Clayton,

1971) or foraminifers (Douglas and Savin, 1975; Barrera et al., 1987;

Barrera and Huber, in prep.). In fact, each of these stable isotope studies, which together cover a broad latitudinal range, suggested a 225 gradual cooling from the early through late Maestrichtian, culminating with an abrupt cooling at the end of the Maestrichtian.

Calcareous nannoplankton distributions in the southern South

Atlantic region do not show changes in diversity and occurrence of

Tethyan species correlative with those observed for the planktonic foraminifers. Pospichal (pers. comm., 1988) reported that the

Maestrichtian nannoplankton assemblages from Maud Rise Sites 689 and

690 are dominated throughout by provincial species, with only rare and sporadic occurrences of Tethyan indicator taxa. Crux (ijj Ciesielski et al., in press) also noted the general absence of Tethyan species throughout the Cretaceous sections of Sites 698 and 700.

Several time series studies of calcareous nannoplankton and planktonic foraminifer paleobiogeography have proven that these microfossil groups responded similarly to watermass changes during the

Recent and Cenozoic (e.g., Cline and Hays, 1976; Haq et al., 1977).

Thus, the absence of correlative changes in taxonomic diversity and provinciality between these two groups during the Cretaceous is puzzling. With so little paleoceanographic data available for the

Late Cretaceous high southern latitudes, speculation on factors controlling the observed changes in the diversity and taxonomic composition of the southern South Atlantic planktonic foraminifers are premature. Greater insight will only be achieved when more stratigraphically complete and more closely spaced sites are recovered from the circum-Antarctic region. 226

TAXONOMIC NOTES

As the species composition of Cretaceous planktonic foraminifers from ODP Leg 114 is nearly identical to assemblages described from ODP

Leg 113 (Chapter III), only original references and brief remarks are presented below for selected taxa that are illustrated on Plates 18 through 20.

GLOBICERINELLOIDES IMPENSUS SLITER

(PI. XVIII, Fig. 1)

Globicerinelloldes impensus Sliter, 1977, p. 541, PI. 6, Figs. 1-3.

Remarks. The Northeast Georgia Rise specimens of this species are identical to specimens described from the Maud Rise (ODP Sites 689,

690) and the Falkland Plateau (DSDP Sites 327, 511). They are characterized by having nearly evolute tests with eight to ten chambers in the final whorl and a subangular equatorial periphery.

The last appearance datum of G. impensus appears to be a synchronous event in the southern South Atlantic Ocean.

HEDBERGELLA MONMOUTHENSIS (0LSS0N)

(PI, XVIII, Figs. 2-3)

Globorotalia monmouthensis Olsson, 1960, p. 74, PI. 9, Figs. 22-24.

Remarks. This species persistently occurs in low to moderate abundance throughout the Globotruncanella havanensis Zone and

Abathomphalus mavaroensls Zone of Sites 698 and 700. It is easily distinguished from Hedbergella sliteri n. sp. by its smaller size and narrower umbilical region. 227

HEDBERGELLA SLITERI N. S P .

(PI. XVIII, Figs. 4, 8)

Hedberqella sliter! n. sp., (see Chapter III).

Remarks. This species is distinguished by its large size, nearly

evolute chamber arrangement, and a broad, shallow umbilical region.

Its range at the northeast Georgia Rise was restricted to the upper

Globotruncanella havanensis Zone through Abathomohalus mavaroensls

Zone, which is comparable to its distribution at the Maud Rise and the

Falkland Plateau (see Chapter III).

HEDBERGELLA SP.

(PI. XVIII, Figs. 5-7)

Remarks. Poorly preserved specimens of this form occur in the £. impensus Zone below Core 114-700B-45R. It differs from fl. sllterl by having six to seven, rather than five to six, chambers in the final whorl and a more axially compressed test. It is also similar to

Hedbergella planisoira (Tappan), but the latter species is smaller, has a smoother test surface and has not been reported above the

Cenomanfan.

ARCHAEOGLOBIGERIMA AUSTRALIS N. SP.

(PI. XVIII, Figs. 9-12; PI. XIX, Fig. 1)

Archaeoglobigerina australis n. sp., (see Chapter III).

R em a rk s. The range of variability in ultimate chamber size, height of the coiling axis, and number of chambers in the ultimate 228

whorl among the Northeast Georgia Rise specimens is similar to the

range observed at the Maud Rise and the Falkland Plateau (see Chapters

II, III). Occurrence of this species throughout the upper Campanian

through upper Maestrichtian at the Leg 114 sites is consistent with

its range at elsewhere in the southern South Atlantic.

ARCHAEOGLOBIGERINA MATEOLA N. S P .

(PI. XIX, Figs. 2-3)

Archaeoglobigerina mateola n. sp., (see Chapter III).

Remarks. Forms of this species are identical to specimens

described from the Maud Rise (Chapter III) . It is distinguished by

its tightly coiled, moderately high spired test, having strong overlap

of the final chamber in the umbilical region, and having a coarsely

pustulose to strongly spinose surface. Its occurs in middle and upper

Maestrichtian sediments at Site 698 and ranges from the early to late

Maestrichtian at Site 700.

RUGOTRUNCANA CIRCUMNODIFER (FINLAY)

(PI. XIX, Figs. 4-10)

G1 ob o t rune ana el rr-umnodifer Finlay, 1940, p. 469, PI. 65, Figs. 150-

157.

Remarks. This species displays a wide range of test size, chamber

arrangement, and test surface ornamentation. Specimens occurring In

the earlier part of its stratigraphic range are generally smaller and

more tightly coiled than specimens from younger sediments (e.g., compare PI. XIX, Figs. 4-5 with Pi. XIX, Figs. 6-9). All specimens 229 display an imperforate peripheral band (PI. XIX, Fig. 10) and a variable degree of pustule alignment parallel to the equatorial periphery. Meridionlly aligned costellae on the umbilical and spiral chamber surfaces are either absent or faintly present.

GLOBOTRUNCANA ARCA (CUSHMAN)

(PI. XX, Figs. 1-2)

Fulvinulina area Cushman, 1926, p. 23, PI. 3, Figs. la-c.

Remarks. This species is very rare at Sites 698 and 700, occurring only from the upper G. havanensis Zone through the &. mavaroensls Zone at both sites,

GLOBOTRUNCANA LINNETANA (D'ORBICNY)

(PI. XX, Figs. 3, 4-7)

Rosalina linneiana d'Orbigny, 1839, p. 101, PI. 5, Figs. 10-12,

Remarks. This species is distinguished from £. area by having a more symmetrical biconvex profile in edge view and a keel band that is parallel to the coiling axis. Although some specimens appear similar to G. area (e.g., PI. XX, Figs. 4-5), they are too rare and too poorly preserved to warrant their distinction as a different species. G. linneiana sporadically occurs in rare within the upper Campanian section of Site 700. Its range elsewhere is reported as Campanian through middle Maestrichtian (Caron, 1985).

GL0B0TRUNCANELLA HAVANENSIS (V00RWIJK)

(PI. XX, Fig. 8) 230

Globotruncana havanensis Voorwijk, 1937, p. 195, PI. 1, Figs. 25-26.

Remarks. This species occurs in rare abundance below the

mavaroensls Zone in several lower to middle Maestrichtian samples at

Sites 698 and 700. It has a similar distribution at the Maud Rise and

the Falkland Plateau, and is the nominal taxon of the G. havanensis

Zone. The reported range in the lower latitudes is from the uppermost

Campanian through the Maestrichtian (Caron, 1985) .

GLOBOTRUNCANELIA PETALOIDEA (GANDOLFI)

(PI. XX, Fig. 9)

G1obo t rune ana (Rugoelobigerina) petaloidea Gandolfi, 1955, p. 52, Pi.

3, Fig. 13.

Remarks. This distinctive species occurs in rare abundance only

within the mavaroensls Zone at Sites 698 and 700. Its

stratigraphic range is from the lower through upp Maestrichtian at

lower latitude localities.

ABATHOMPHALU5 MAYAROENSIS (BOLLI)

(PI. XX, Fig. 10)

G1obo t rune ana mavaroensis Bolli, 1951, p. 190, PI. 35, Figs. 10-12.

Remarks. This species has proven to be an excellent marker in the high southern latitudes for the late Maestrichtian. 4- mavaroensis has a nearly identical range as the upper Maestrichtian calcareous nannoplankton species Nephrolithus freauens at the Maud Rise as well as at Sites 698 and 700. Plate XVIII. Fig, 1. Globjgerinelloides impensus Sliter, Sample 114-700B-43R-3,140-144. Figs. 2-3. Hedbergella monraouthensis (Olsson), Sample 114-698A-16R-2,67-71. Figs. 4, 8. Hedbergella sliteri n. sp., Sample 114-698A-16R-2,67-71. Figs. 5-6. Hedbergella sp., Sample 114-700B-47R-4,25-29. Fig. 7. Hedbergella sp., Sample 114-700B-46R-1,124-128. Figs. 9-10. Archaeoglobigerina australis n. sp., Sample 114-698A-17R-1,28-32. Figs. 11-12. Archaeoglobigerina australis n. sp. , Sample 114-698A-17R-2,12-16. Scale bar for all figures is 50 microns.

231 232

Plate XVIII Plate XIX. Fig. 1. Archaeoglobigerina australis n. sp., Sample 114-698A-17R-1,28-32. Fig. 2. Archaeoglobigerina mateola n. sp., Sample 114-698R-16R-1,67-71. Fig. 3. Archaeoe!obigerina mateola n. sp., Sample 114-16R-1,67-71. Figs. 4-5. Rugotruncana rirr.^nodlfer (Finlay), Sample 114-698A-17R-1,12-16. Figs. 6-7. Rugotruncana circuinnodifer (Finlay), Sample 114-698A-16R-1,67-71. Figs. 8-9. Rugotruncana clrcumnodifer (Finlay), Sample 114-698A-16R-1,67 - 71. Fig. 10. Closeup view of imperforate peripheral band and beaded keel of same specimen shown in Figs. 8-9. Scale bars for Figs. 1-9 is 50 microns and for Fig. 10 is 10 microns.

233 234

Plate XIX Place XX. Figs. 1-2. Globotruncana area (Cushman), Sample 114- 698A-16R-1,67-71. Figs. 3, 6-7. Globotruncana linneiana (d'Orbigny), Sample 114-700B-47R-5,12-16. Figs. 4-5. Globotruncana linneiana (d'Orbigny), Sample 114-700B-47R-4,25-29, Fig. 8. Globotruncanella havanensis (Voorwljk), Sample 114-698A-17R-2,12-16. Fig. 9. Globotruncanella petaloidea (Gandolfi), Sample 114-700B-39R-4,72-76. Fig. 10. Abathomphalus mavaroensls (Bolli), Sample 114-698A-16R-1,67- 71. Scale bars for Figs. 1-10 is 50 microns.

235 236

Plate XX

10 CHAPTER V

PALEOBIOGEOGRAPHY OF CAMPANIAN-MAASTRICHTIAN FORAMINIFERS IN THE

HIGH SOUTHERN LATITUDES

ABSTRACT

Distribution data for Campanian-Maastrichtian planktonic and benthic foraminifers are used to infer Antarctic land-sea distributions, depict changes in the positions of the Tethyan,

Transitional, and Austral provinces, and portray oceanic surface gyre configurations. Distinctive similarities among nearshore benthic and open ocean planktonic foraminifer assemblages from the southern South

Atlantic and southern southwest Pacific regions suggest the presence of shallow marine seaways within West Antarctica during the Late

Cretaceous. Occurrence of recycled Cretaceous marine microfossils at numerous Antarctic localities also argues for the former presence of intra-Antarctic marine basins. Plots of poleward changes in total and keeled planktonic species diversity in the Southern Hemisphere are compared for the early and late Campanian and early and late

Maastrichtian. Latitudinal diversity gradients are weakest during the early Campanian and become more pronounced during the late Campanian and early Maastrichtian. Five planktonic species endemic to the

Austral Province first appear during the late Campanian and the early

Maastrichtian. Progressive biogeographic isolation of Austral

237 238

Province assemblages is inferred to reflect development of a major

vatermass boundary separating cool surface waters south of about 50°S

paleolatitude from warmer surface waters to the north. An influx of

thermophilic planktonic foraminifers, including both keeled and non

keeled forms, to the high southern latitudes occurred during the late

Maastrichtian. This may have been caused by a temporary poleward

expansion of the Tethyan Province and a concommittant enhancement of

surface water stratification.

INTRODUCTION

Analysis of various geological data from the polar regions is

essential to reconstructing the Late Cretaceous paleoceanographic and

paleoclimatic history of the earth. Small changes in high latitude

land-sea distributions have strongly affected global atmospheric and

oceanic circulation patterns and temperature distributions during the

geologic past (Barron, 1983). High latitude planktonic foraminifers

are particularly well-suited as indicators of paleoclimatic change

since their patterns of areal and vertical distribution are regulated

by seasonal and long-term changes in surface water temperature,

density stratification and other climatically regulated physico

chemical parameters. Furthermore, polar foraminifers may be used to

record the minimum temperature extremes of global paleoclimate if 1)

the stable isotopic composition of their shells is unaltered and 2)

their distribution was not influenced by local basinal conditions.

High latitude sites yielding Upper Cretaceous foraminifer assemblages

that meet both of these criteria occur only in the Southern 239

Hemisphere. However, these are very limited in their stratigraphic

and areal extent.

Our ability to resolve the geologic history of the Late Cretaceous

polar regions is hampered by difficulties in cross -latitudinal

correlation resulting from poor biostratigraphic resolution. Results

from Ocean Drilling Program (ODP) Legs 113 and 114 (see Chapters III

and IV) mark an improvement in high southern latitude biostratigraphy,

but a more precise chronostratigraphic framework is still needed. The

most detailed information on climatic and oceanographic conditions in

the Late Cretaceous high latitudes has been obtained from Campanian-

Maastrichtian sediments in the southern South Atlantic and southwest

South Pacific Ocean. Therefore, this chapter will concentrate on

interpretation of that time period, with a brief review of existing data from older Cretaceous deposits from other circum-Antarctic

localities.

The taxonomic composition of nearshore benthic and planktonic and deep-sea planktonic foraminifer assemblages will be compared among sites in high paleolatitudes (poleward of 50°S) to enable interpret the extrinsic factors controlling their distribution. Stratigraphic and latitudinal variations in the Late Cretaceous paleobiogeographic distribution patterns will be discussed for the Campanian-

Maastrichtian time interval.

SOUTHERN HEMISPHERE FALEOGEOCRAPHY

CONTINENTAL DISTRIBUTIONS 240

The dispersal history of remnant Late Cretaceous Gondwana continents, which included Antarctica, Australia, South America, New

Zealand, and New Guinea, strongly affected biotic distributions because of resultant changes in marine circulation. Significant continent motion can be briefly summarized as follows: 1) migration of

New Zealand from 80°S at 95 Ma (Oliver et al., 1979) to 62°S by 75 Ma

(Grindley et al., 1977); 2) inception of slow rifting between the

Australian and Antarctic margins at about 95 Ma and initiation of rapid northward movement at about 48 Ma (Veevers, 1984; Cande and

Mutter, 1982); 3) slow northward movement of South America and separation from the Antarctic Peninsula throughout the Late Cretaceous

(Lawver et al., 1985); and 4) continued widening of the South Atlantic

(Smith et al., 1981). The southern tip of India was located at about

60°S during the late Albian and migrated northward to about 45°S by the early Maastrichtian (Barron, 1987). Geophysical studies suggest that the Kerguelen Plateau, which stretches between 46° and 64°S in the southern Indian Ocean, has remained in its present location throughout the breakup of the Gondwana continents (Schlich, 1982). Continental terranes comprising West Antarctica (Dalziel and Elliot, 1982) were rearranged into their present configuration by about 100 Ma (Watts et al., 1984). The Antarctic continent occupied a polar position throughout the Late Cretaceous (Smith et al., 1981; Lawver et al.,

1985; Barron, 1987).

Communication between the North and South Atlantic Ocean basins was probably established by the end of the Albian, but gateways for bottom water circulation were not present until at least the Santonian 241

(Berggren, 1982). Lawver et al. (1985) showed that the South Atlantic basin was little more than half its present size by the end of the

Cretaceous. The South Pacific basin, on the other hand, was very broad and effectively isolated from deep water communication with the other ocean basins (Smith et al., 1981).

ANTARCTIC PALEOGEOGRAPHY

The thick Ice sheet covering the Antarctic continent has inhibited our ability to sample sediments from the continental interior.

Consequently, inferences on the Cretaceous paleogeography of

Antarctica, which have an important bearing on paleoclimatic and paleoceanographic models, depend on indirect information from a very limited database. The primary indicators of Cretaceous Antarctic paleogeography come from: 1) in situ sediments deposited in peripheral

Antarctic localities; 2) distribution of recycled marine and non marine microfossils; 3) circum-Antarctic faunal and floral paleobiogeographic distributions; 4) the modern subglacial topography of Antarctica; and 5) the history of late Mesozoic tectonism in

Antarctica.

In situ Antarctic marine sediments of Cretaceous age are only known from the James Ross Basin and Alexander Island in the northern

Antarctic Peninsula (sites 1 and 7 on Figs. 35 and 36). Sediments on

Alexander Island have yielded Lower Cretaceous and older ammonites and bivalves (Crame, 1982; Thomson, 1982), but no Upper Cretaceous fossils. A thick succession of clastic, shallow marine sediments, ranging from Albian to early Tertiary in age (Fig. 36), crop out in Figure 35. Paleogeographic reconstruction map for 80 Ma (after Smith et al.p 1981) showing locations of land-based and deep sea sediments within the Cretaceous Austral Province that yield in situ marine invertebrates, including foraminifers (bold numbered sites 1-6, 9-14) and molluscs (bold numbered sites 1-8). Sites yielding reworked Cretaceous marine and terrestrial microfossils are also shown (bold numbered sites 15-20). In situ terrestrial microfossils were found at locality 21. 1 — James Ross Island region; 2 - southern Chile; 3 — southern Argentina; 4 — New Zealand; 5 — Great Artesian Basin; 6 — Otway Basin; 7 - Alexander Island; 8 - South Georgia; 9 - Falkland Plateau (DSDP Sites 327A and 511); 10a - Weddell Basin ODP Leg 113 (Sites 689, 690); 10b - Weddell Basin, ODP Leg 113 (Sites 692, 693); 11 - ODP Leg 114 (Sites 698 and 700); 12 - Lord Howe Rise DSDP Leg 21 (Site 208); 13 - Burdwood Bank; 14 - Kerguelen Plateau ODP Legs 119 and 120 (Sites 738, 748, 750); 15 - King George Island; 16 - Taylor Valley; 17 - Transantarctic Mountains; 18 - Weddell Basin; 19 - Ross Sea DSDP Leg 28 (Site 270); 20 - Prydz Bay ODP Leg 119 (Sites 739, 741); 21 — Operation Deep Freeze Core 38. Italicized numbers refer to Southern Hemisphere DSDP sites yielding Upper Cretaceous foraminifers. See text for references.

242 243

tan

E l f fit. t»BT If Ota. ttt« 1 Wannaft. iat2

AUSTAAL PROVINCE LOCALITIES k

In alia plank taMc I « baninic i«r«MiRir*i* Othar In ana marina foaalla Raeyelaa Cratscaoaa marina mtarafaaalia RncpelaE Cralaeaoaa lal mlarafaaalla

Figure 35. Figure 36. Stratigraphic ranges of Cretaceous land-based, deep- sea, and recycled marine sediments recovered from within the Austral Province. Numbers in parentheses correspond to site locations shown in Fig. 35. 9 H vn O ■< fn «• o 9 m C ►

* > a ' • n • 1 > m > • f ! f t 2 • O % • “• • b* < lTH b* * m A T mm 8 ■ ■ ■ ■■■■■i LATE CRETACEOUS S EARLY CRETACEOUS a

Figure 36. 246 several localities in the Janes Ross Island region (see map, Chapter

I, Fig. 2). This sequence has yielded abundant and well preserved remains of fossil invertebrates, vertebrates, and plants, and is a key site for a variety of late Mesozoic-early Tertiary paleontologic studies (see references in Ineson et al., 1986, and Feldmann and

Woodburne, 1988).

Provenance studies of clastic sedimentary rocks deposited along the eastern margin of the northern Antarctic Peninsula indicate that a major episode of uplift and volcanism led to the construction of an emergent arc terrain during the Early Cretaceous (Farquharson, 1982;

Dalziel & Elliot, 1982; Macellari, 1988). It is uncertain, however, whether the peninsula region existed as a continuous landmass or as a series of islands separated by shallow marine seaways. Pollen (Askin,

1988) and fossil wood (Francis, 1986) occur throughout the upper

Campanian through lower Tertiary sequence in the James Ross Island region, indicating that at least some parts of the Antarctic Peninsula were above sea level and forested during that time, Woodburne and

Zinsmeister (1984) favored a relatively continuous land connection, extending from southern South America to Australia, to explain the dispersal pattern of Upper Cretaceous and lower Tertiary marsupials.

On the other hand, Zinsmeister (1982), Macellari (1985), and Huber &

Webb (1986) deomnstrated strong taxonomic affinities among Upper

Cretaceous shallow marine invertebrates from southern South America, the northern Antarctic Peninsula, New Zealand, and southeast

Australia, and indicated that shelfal marine communication must have existed between these regions. The paleobiogeographic significance of 247

foraminifers from the James Ross Island region in reconstructing

Antarctic paleogeography will be discussed in a later section.

Seafloor magnetic anomaly data from the southeast Pacific and

geological evidence from the Antarctic Peninsula and southern South

America suggest that active subduction occurred along the western

margin of South America-Antarctic Peninsula in the early Jurassic and

continued through the Cretaceous (Dalziel and Elliot, 1982; Elliot, in

press), with concurrent back-arc spreading east of this zone.

Episodes of rifting between southern South America and the northern

Antarctic Peninsula, associated with the breakup of Gondwana, probably

allowed periodic deep water communication between the Pacific and

Atlantic Ocean basins (Elliot, pers. comm., 1988). It is Just as

likely that island arc volcanism and uplift could have interrupted the deep water flow, allowing terrestrial migration across a narrow

isthmus. Unfortunately, the geologic record is too poorly preserved to accurately reconstruct the timing of these inferred events (Dalziel and Elliot, 1982).

The only known in situ Cretaceous sediments in East Antarctica range from Aptian to Albian in age, and were deposited in non-marine environments. Domack et al. (1980) reported abundant pollen and spores of Aptian age from siltstones cored in a 1407 m deep basin off the George V Coast (site 21 on Fig. 35; Table 6). Aptian-Albian pollen and spores were in a laminated siltstone sequence cored during

ODP Leg 119, at Site 741 (site 20 on Fig. 35) on the Prydz Bay shelf

(Truswell, pers. comm., 1988). This interval was encountered 45 m below the sea floor and 551 m below sea level. 248

> 11: l o c a t i o n AGE DEPOSITIONAL DEPOSITIONAL REFERENCE (Lat., long., depth) ENVIRONMENT BASIN

IN SITU Offshore George V Coast Aptian non Marine Wilkes Basin DoMAck et a l ., (6T°S, TH6°E; 1H07 ■) (spores A pollen) 1930

Prydz Bay OOP Site 791 Aptlan~Albian non earlne Amery Basin Truswsl1, pars. (68°, 77 , 551 *) faporus & pollen) c o m m . * 1986

REWORKED Shackleton Ice Shelf late Paleocene* ■arine Aurora Basin Truawell, 1933 (65°, 96°) Eocene (dinocysts) latest Cretaceous* non Marine Aurora Basin Truawell, 1963 Paleocene (pollen) Late Jurassic- non marine Aurora Basin Truswell* 1963 Early Cretaceous (spores A pollen) Late Carboniferous* non earlne Aurora Basin Truawell, 1903 Persian (spores)

Offshore Wilkes Land latest Cretaceous- sarlne Wilkes or Truawell, 19B3 (65°, 134°) Eoccne (dlnoaysts) Aurora Basic aid Cretaceous non Marine Wilkes or Truswell, 1963 (spores & pollen) Aurora Basin

Offshore George V Eocene ■arlne Wilkes Basin Truswall, 1963 Land (66°, HUt°) (dinocysts) Late Cretaceous* non Marine Wilkes Basin Trusvell, 1963 Paleocone (spores A pollen) Early Cretaceous non Marine Wilkes Basin Truswsl1, 1963 (spores A pollen) Early Cretaceous ■arlne Wilkes Basin Truawell, 1967 (dinocysts)

Offshore Queen Maud Late Jurasslc- noamarine uncertain Truswsl1, 1963 Land (70°-T6°, 10-110°) Tertiary (pollen A spores) Cretaceous* ■arlne uncertain Truswell* 1963 early Tertiary (dinocysts)

Prydz Bay shelf Late Cretaceous* non Marine Amery Basin Keep, 1972 (66°, 77°) early Tertiary (spores k pollen) Albian non Marine Amery Basin Kemp, 1972 (spores A pollen) Persian non Marine Amery Basin Keep, 1972 (spores) Late Cretaceous Marine Amery Basin Thiers tain, per; (calc, nannos) c o m m .* 1966 Eocene ■arlne Aaery Basin Heap, 1972 (dinocysts)

Bo93 See region Late Cretaceous marine Ross or Byrd Webb A Neal I, (72°-77°, 161-170°) (foremf nlfera) Baa in 1972 Late CreLaceoua murine Russ or Byrd Ltrckle A Webb, (foraalnlfera) basin 1966 Early Cretaceous* non marine Rosa Sea basins Truswell, 1983 early Tertiary (pollen A spores) or Byrd Basin

Transantarctlc Hts. Late Cretaceous* ■arine Wilkes or Pen Webb et al. , (86°, 90°) Eocene (foraalnlfera) sacola Basin 193* 249

Reworked non-marine palynomorphs of Cretaceous age were reported

by Kemp (1972) and Truswell (1983) from numerous sites offshore East

Antarctica, including the margins of George V Land, Uilkes Land, Prydz

Bay, the Ueddell Sea, and the Ross Sea (Figs. 35, 36; Table 6). These

pollen and spores occur in Recent marine sediments and were probably

transported from their original sites of deposition by a variety of

glacial and submarine processes.

Recycled Cretaceous marine microfossils also occur at several

localities within and around East Antarctica (Fig. 35; Table 6).

Reworked Upper Cretaceous calcareous nannoplankton were occur in younger glaciomarine sediments at several of the Prydz Bay sites (Fig.

35 site 20) drilled during ODP Leg 119 (H. Thierstein, pers.comm.,

1988). Foraminifers of probable Campanian-Maastrichtian age were

reported from Taylor Valley (Fig. 35 site 16; Webb and Neall, 1972)

and DSDP Site 270 (Fig. 35 site 19; Leckie and Webb, 1986) in the Ross

Sea region, the Transantarctic Mountains (Fig, 35 site 17; Webb et

al., 1984), and from King George Island (Fig. 35 site 15; Birkenmajer et al., 1983). Reworked Cretaceous marine dinocysts were found offshore George V Land, Wilkes Land, and Queen Maud Land, and in the

Ross Sea (Fig. 35; Truswell, 1983; 1987). These occurrences of

reworked marine microfossils in Antarctic interior and peripheral localities suggest that the microfossils were derived from marine sediments preserved beneath the present Antarctic ice sheet.

The subglacial topographic map of Drewry (1983), which depicts the surface elevation of Antarctica with the modern ice sheet removed and bedrock isostatically adjusted, identifies several large intracratonic 250 depressions that may have been sites for marine deposition during non glacial times (Fig. 37). One of these depressions, the Wilkes

Subglacial Basin, extends about 1400 km south from the George V Coast to 83°S. It ranges between 600 and 100 km in width, and attains a depth In excess of 1000 m below sea level in some areas. The Wilkes

Subglacial Basin has been considered as a likely source for the reworked Cretaceous marine microfossils found on the western Wilkes

Land shelf and in the Transantarctic Mountains (Webb et al., 1984;

Truswell, 1987). Bradshaw (1987) postulated that the Wilkes

Subglacial Basin and other basins along the Antarctic-Australian margins formed over 100 Ma from extension and rifting during the breakup of Gondwana.

The Aurora Subglacial Basin is broader, but shallower, than the

Wilkes Subglacial Basin (Fig. 37). Recycled Jurassic to Eocene non marine palynomorphs occur seaward of the Aurora Subglacial Basin, and

Tertiary or older marine microfossils are absent. These characteristics suggest that this part of East Antarctica was subaerially exposed during the late Mesozoic, although the basin may have been periodically submerged during high stands of sea level.

Other intracratonic depressions that may have occasionally been flooded by marine seas during the non-glacial past include the

Pensacola and Amery Subglacial Basins in East Antarctica and the Ross and Byrd Subglacial Basins in West Antarctica (Fig. 37). The

Pensacola Subglacial Basin, which extends poleward of the Wilkes

Subglacial Basin and then continues northward, probably formed during extensional tectonics related to the late Mesozoic breakup of Gondwana T------1------7 o*

J a mss Ross is. Weddell Sta

Alexander ts.

Amundsen

Elevations rotative to current sea tevet Ross Sea

Figure 37. Subglacial topography map after Drewry (1983) showing the location of major 251 subglacial basins inferred to be sites of sediment deposition during the non-glacial past. 252

(Elliot,, pers. comm. , 1988). This basin was identified as

anotherpossible source of reworked marine microfossils in the

Transantarctic Mountains (Webb et al., 1984). Recycled Upper

Cretaceous calcareous nannoplankton on the Prydz Bay shelf (see above)

indicate that the Amery Subglacial Basin was covered by marine seas at

some time during the late Mesozoic, but the extent of coverage cannot

be determined in the absence of in situ marine sediments. Stagg

(1985) proposed that the Amery Subglacial Basin formed as a possible

failed rift arm of a triple junction during Early Cretaceous Indo-

Antarctic breakup.

Truswell and Drewry (1983) determined that the Victoria Land,

Central, and Eastern Basins (all beneath the Ross Sea) and Byrd

Subglacial Basin (north of the Transantarctic Mountains in West

Antarctica) may have been sources for recycled Cretaceous palynomorphs

found in Recent sediments of the Ross Sea. Their conclusion was based

on present patterns of ice drainage into the Ross Ice Shelf. The Ross

Sea basins probably formed during post-Paleozoic crustal extension and

rifting (Davey, 1987). The oldest in situ marine rocks from this

region, recovered from the CIROS-1 drillhole on the western edge of

the Victoria Land Basin, are dated as early Oligocene (Barrett et al.,

in press). Barrett et al. (in press, Fig. 2) estimate that up to 1 km

of post-Jurassic sediments underlie the early Oligocene sequence

drilled at the CIROS-1 site. Little is known about the late Mesozoic history of the Byrd Basin, which encompasses most of West Antarctica

(Fig. 37). Drewry's (1983) map shows that bedrock depth is more than

1000 m below sea level in large portions of this basin, and in some 253

areas, more than 2000 m In negative relief. These deep troughs may

have been generated from the same late Cenozoic extenslonal tectonic

processes observed in the Ross Sea basins and Transantarctic

Mountains, and therefore, should not be used to characterize the older

paleotopography (Elliot, pers. comm., 1988).

Uplift of the Transantarctic Mountains, which form the northern

margins of the Wilkes and Pensacola Subglacial Basins (Fig. 37),

probably occurred after about 50 Ma (Gleadow and Fitzgerald, in

press). The earlier Cenozoic and late Mesozoic topography of this

region is poorly constrained becaused of a lack of geologic

information. Plant remains and freshwater Invertebrates have been

found interbedded with the Jurassic Kirkpatrick Basalt and Ferrar

Dolerite at numerous localities in the Transantarctic Mountain belt,

indicating extrusion in a terrestrial environment (Barrett et al.,

1986). Thick accumulations of older Mesozoic and Paleozoic sediments

below the Jurassic basalts and dolerites suggest deposition at low

elevations (Barrett et al., 1986), but the duration and lateral extent

exposure event area cannot be determined from the existing sedimentary

record.

In summary, paleontologic, sedimentologic and geophysical data

from the Antarctic interior and circum-Antarctic regions afford

important generalizations on pre-glacial Antarctic paleogeography.

First, interior seaways probably traversed much of West Antarctica and parts of East Antarctica at various times in the late Mesozoic and

early Tertiary. Shallow, epeirlc seas may have inundated the Wilkes,

Pensacola, Amery, and Ross Sea basins, and possibly the Aurora Basin, 254 covering as much as 30% of the Antarctic continent during high stands of sea level. Second, marine communication between the Ross, Wilkes, and Pensacola Basins may have existed prior to the first (mid Eocene) phase of Transantarctic Mountain uplift. This would have enabled marine communication between East and West Antarctica, providing a source for heat transport to the polar center of Antarctica. There is no evidence that highlands existed along any part of the

Transantarctic Mountain belt prior to their Cenozoic uplift. Instead, this region was probably subaerially exposed along a narrow belt of lowlands that were bordered by and, in some places, dissected by shallow seaways. Finally, post-Paleozoic changes in plate motion and tectonism related to the breakup of Gondwana caused episodes of rifting, volcanism, and uplift resulting in dramatic paleogeographic changes within East and West Antarctica and between the Antarctic

Peninsula and southern South America. This may account for seemingly contradictory dispersal patterns inferred from terrestrial and marine fossil biota during the Late Cretaceous and early Tertiary. However, the timing and extent of these events is poorly constrained from the available geologic record.

CONSTRAINTS OF THE HIGH LATITUDE ENVIRONMENT

Seasonal changes in solar radiation are most pronounced in the polar regions. These produce dramatic variations in a vast array of physical environmental parameters, including temperature, salinity, nutrient upwelling, and depth of the photic zone, and are very important in regulating population dynamics and distributional 255

patterns in the marine biosphere. Valentine (1982) noted that the two

main adaptations to environmental instability caused by seasonality,

termed "seasonal strategies", are 1) to increase reproduction and 2)

to fortify the populations against decrease during inclement

conditions. Numerous examples of organisms that apply these

strategies are in modern high latitude marine and terrestrial

environments. Predominance of low diversity/high dominance fossil assemblages from polar regions suggests that these generalist

strategies have operated throughout geologic time.

Among foraminifer habitats, the effects of seasonality are most pronounced within the pelagic realm. This is indicated in modern oceans by the parallel between planktonic foraminifer species diversity gradients and latitude. Maximum species diversity is in tropical regions, where a total of 24 species are present, whereas only 5 species occur in polar waters (B6, 1977). Be (1977) noted that the ratio of indigenous to total species present within the modern

Arctic and Antarctic Provinces is much lower (1:5) than in the

Tropical Province (14:24). This would suggest that evolutionary rates of planktonic foraminifers are faster in the tropics than the high latitudes.

In addition to adapting to withstand environmental variablity caused by intense seasonality, polar biota must adapt to an environment which has a cooler mean annual temperature than lower latitude regions. Although this is much more severe during glacial times, it may still have been a limiting factor for many thermophilic taxa during pre-glacial periods. 25S

In modern polar oceans, the short duration of the summer season and intensity of surface wind shear inhibit density and temperature stratification in the surface waters, whereas tropical waters are well-stratified throughout the year (Fig. 38). The vertical structure of Cretaceous high latitude surface waters is poorly known, but it is probably safe to assume that surface to bottom water temperature and density gradients were not as well developed as in equatorial regions.

The limited diversity of planktonic foraminifer morphotypes from Late

Cretaceous high latitude sites may reflect habitation in a poorly stratified water column, as will be discussed below.

PLANKTONIC FORAMINIFER DEPTH STRATIFICATION

Meridional changes in the intensity of solar radiation and surface water density stratification have a strong control on the distribution of phytoplankton and zooplankton in the upper water column. In equatorial regions, the high insolation angle enables relatively deep penetration of solar radiation. In these latitudes, there is a stable magnitude of primary productivity, and the water column is well stratified. On the other hand, the euphotic zone in polar seas is much shallower during the peak summer season, the surface waters are more convective, and productivity is intensely seasonal. A transect across the North Pacific Ocean during late summer demonstrated that the chlorophyll maximum at 55°N comes to within 40 m of the surface, whereas this layer is at 120 m depth In the lower latitudes (Apel,

1987, Fig. 9.30a). These physical oceanographic differences between the high and low latitudes help to explain poleward changes in the 257

density j-.

23 24 25 26 7 28 0

EQUATOR IOOO TROPiCS

HIGH LATITUDE 2000

3 0 0 0

4 0 0 0 b

-5 0

E -100 ..Chlorophyll maximu ~ 75% of m a x i m u m '50% Of maximum

* - 1 55* W

-200

25 40 45 55 60 Latitudt. A Ideg)

Figure 38. a). Typical density/depth profiles for modern low and high latitude oceans showing differences in surface water stratification (from Pond and Pickard, 1984). b). North Pacific Ocean latitudinal changes in depth of the chlorophyll maximum zone, which reflects depths of peak phytoplankton productivity, measured along a transect at 155°W longitude during early summer. Note that the poleward shallowing of the chlorophyll maximum occur becaused of a shallowing photic zone (from Apel, 1987). 258 diversity, population dynamics, and vertical distribution of planktonic foraminifers.

MODERN SURFACE WATER DISTRIBUTIONS

A comprehensive review of the vertical distribution of modern planktonic foraminifers was provided by B6 (1977). He noted that planktonic foraminifers tend to live in the euphotic zone where food supplies, particularly the phytoplankton upon which foraminifers feed, are most plentiful. The highest concentrations are generally at depths below 10 m and above 100 m, but some living specimens have been encountered below 1000 m. Observations from plankton tows, suspended sediment traps, and oxygen isotope compositions of foraminifer test, have shown that planktonic foraminifers exhibit a marked depth stratification, with some species inhabiting greater depths than others.

(1977) recognized three broad groups which characterize particular depth habitats. These include "shallow water" species that inhabit depths above 50 m, "intermediate water" species inhabiting depths between 50 and 100 m, and "deep water" species where adult specimens occur predominantly below 100 m. Differences in shell morphology among these groups can be explained as adaptational strategies for inhabiting different levels of the surface water column. B6 (1980) suggested that depth control is regulated by the addition of calcite to the foraminifer shell during ontogeny.

Globulose, thin-walled juveniles, which inhabit the uppermost surface waters, transform their shells during development by chamber 259 thickening and addition of surface ornament, increasing their depth habitat with increased shell density. Maximum depth is attained just prior to reproduction (Be, 1980). Small, thin-walled, and globulose adult forms inhabit the surface waters throughout their relatively rapid reproductive cycle (Fig. 39). On the other hand, deep water species inhabit the euphotic zone as juveniles and migrate below 100 m as adults. Their life cycles are longer and their test morphologies change during ontogeny from thin walled, globulose juveniles to thicker walled, non spinose adults, including both globulose and compressed forms with peripheral keels (Fig. 39).

CRETACEOUS DEPTH STRATIFICATION

Depth stratification among Cretaceous planktonic foraminifers has been verified by oxygen isotope (Douglas and Savin, 1975) and biofacies profile studies (Eicher and Worstell, 1970; Sliter, 1972;

Hart and Bailey, 1979). Species with the lowest (warmest) i1B0 values dominate shallow water assemblages. These are predominantly biserial, planispiral and low trochospiral forms with globular chambers and thin test walls. Species yielding heavier (cooler) oxygen isotopic ratios are generally absent from shallow water biofacies and are inferred to have inhabited greater depths. The deepest dwelling Upper Cretaceous taxa are typically the most ornate forms with thick chamber walls, coarse surface costellae, and peripheral keels. These include most species of the Globotruncanidae.

Several authors have related Cretaceous planktonic foraminifer species diversity and evolutionary trends to iterative attempts at 260

OP/* N?* ( short \ I i f e - c y c le ) /uvenlles lit e-c yc les (feeding level) rapidly mature v ^ p r l m l t l v type 0H adults V V . V 0i more C O f l i p / « X ^ adults adults (sexual repro

duction level) stratification density d a a p a s adult t morphotype decreasing competition, opportunities for speciation, maintenance of species

Figure 39. Life cycles and depth stratification inferred for modern and Cretaceous shallow, intermediate, and deep water planktonic foraminifera. From Caron and Homewood, 1983. 261 colonizing deeper levels in the water column (Hart, 1980; Caron and

Homewood, 1983; Leckie, 1987). Caron and Homewood (1983) postulatedthat these trends have been regulated by changes in the marine environment. They suggest that globular ("simple"), shallow dwelling species were well adapted to highly convective ocean environments because of their rapid reproductive cycles and high fecundity. These authors also speculated that times of ocean stability and enhanced vertical density stratification allowed morphologic diversification among planktonic foraminifers because of increased competition to inhabit density-stratified niches in the surface waters.

Similar arguments could be used to explain meridional trends in the distribution of Upper Cretaceous planktonic foraminifers. High latitude assemblages of this age are characterized by low species diversity, dominated by simple, globular species, and lack complex, keeled taxa (see the following section for a more detailed discussion of the geographic distributions). The poleward reduction in planktonic foraminifer species diversity and loss of keeled morphotypes can be explained by a concomittant poleward shallowing of habitable niche space in the water column (Fig. 60). Adaptational strategies to occupy a shallower depth habitat in the polar regions would be favored because of: 1) the shallower zone of phytoplankton productivity (resulting from a lower insolation angle); 2) more convective, and therefore, poorly stratified surface waters; and 3) greater seasonality in food and nutrient supplies causing instability in the surface water environment. The Upper Cretaceous polar Figure AO. Diagrammatic portrayal of factors influencing the depth habitats of Upper Cretaceous planktonic foraminifers. The poleward loss of stenothermal, keeled (deeper dwelling) morphotypes may have been related to a concomitant shallowing of the photic zone (due to decreasing insolation angle and increased seasonality). Note the poleward reduction in meridional ornament on the figured rugoglobigerine morphotypes.

262 NORTH SOUTH POLE SUBTROPICS TROPICS SUBTROPICS POLE

Shallow Photic Zona

Shallowing Dapth Shallowing Dapth Habitat Habitat

Oacraaaing Vortical Oanalty Gradient 263

Figure 40 264 assemblages of planktonic foraminifers have all the morphologic characteristics of opportunistic colonizers (sensu Caron and Homewood,

1983) inhabiting shallow depths in a poorly stratified water column.

PREVIOUS STUDIES OF THE CRETACEOUS SOUTHERN. EXTRA-TROPICAL

BIOGEOGRAPHIC PROVINCE

A variety of criteria and several names have been used to distinguish a Cretaceous biogeographic province in the high southern latitudes, as shown in Table 7, The name "Palaeoaustral" was first introduced by Fleming (1963) and later used by Stevens (1980) to include localities in the circum-polar region that show similar taxonomic affinities among Mesozoic and Tertiary shelfal marine and terrestrial organisms. He characterized Palaeoaustral elements as having poor dispersal capabilities and suggested that their present distribution reflects past shallow marine linkages between southern

South America, Antarctica, Australia, New Caledonia, and New Zealand.

Fleming (1967) subsequently used the name "Austral" to define the same biogeographic unit. Variation in the number of endemic versus cosmopolitan species was correlated by Fleming (1967) with Mesozoic orogenic episodes in the southwest Pacific region.

Kauffman (1973) based definition of the Austral Province on an increase in the percentage of endemic bivalve species (22.6% Initial endemism) within the southwestern Pacific region during the latest

Jurassic or earliest Cretaceous. His concept of the Austral Province included Australia, New Zealand, New Caledonia, New Guinea, and smaller, poorly studied islands in the southwest Pacific region. 265

Kauffman ascribed a combination of tectonic and ecologic causes for the development of the Austral Province (Table 7).

Zinsmeister (1979, 1982) suggested that Kauffman's (1973) Austral

Province lost its identity during the Late Cretaceous due to continued separation of the Gondwana continents. He proposed the name

"Weddellian Province" to include Upper Cretaceous -lower Tertiary shelfal marine faunas remaining in the high southern latitude region, including southern South America, the Antarctic Peninsula, New

Zealand, and the eastern margin of Australia. Detailed analysis of the Southern Hemisphere distribution of Upper Cretaceous ammmonites led Macellari (1985, 1987) to adopt a similar usage of the Weddellian

Province concept.

Webb (jjj Hornibrook, 1969) favored the existence of a temperate climatic zone (southern, extra-Tethyan area of Webb, 1973a, b) in the high southern latitude region of New Zealand based on the absence of characteristically Tethyan planktonic foraminifer genera. He noted that New Zealand assemblages completely lacked species of Schackoina.

Clavihedbergella. Ticlnella. Rotallpora. Praeelobotruncana.

Planoelobulina. Fseudotextularia. and Globotruncana. whereas planktonic taxa such as Guembelitria. Heterohelix. Gublerina.

Hedberpella. Globlgerlnelloldes. Rueoglobigerlna. Rugotruneana. and

Abathomphalus are quite common.

The foraminifer Austral Province was recognized by Scheibnerova

(1971, p. 139) based on the dominance of agglutinated and calcareous benthic foraminifer assemblages "bearing clear features of forms living in cool environments" and low taxonomic diversity of planktonic Table 7. Biogeograpbio terminology of the southem, extra-tropical region during the Cretaceous.

DANE PALAEOAUSTRAL WEDDELLIAN AUSTRAL ELEMENT PROVINCE PROVINCE

AUTHOR Fleming, Stevens, Zlnsaeister, Macellari, Fleming, Kauffman, Scheibnerova, Sllter, 1977, This Study 1962 1980 1979, 1982 1985, 1987 1967 1973 1971, 1973 Krasheninnikov A Basov, 1983, 1986

FOSSIL shallow shallow bivalves A ammonites bivalves, bivalves planktonic planktonic planktonic GROUP marine, aarlne, gastropods gastropods and benthlc foraalnlfers A benthlc terras t. terrest. foraalnlfers foraalnlfers biota biota

BASIS POR faunal A fauaal A faunal faunal faunal faunal absenoe of absence of endealsa, RECOG. floral floral endealsa endealsa endealsa endealsa tropical tropical low div., •ndealsa end salsa speoies, speoies, absenoe of low divers. low divers. tropical species

TIME OF Early Early Late Late Aptian Early Early Aptian pre- DEVELOP. Cret. Cret. Cret. Cret. Cret. Cret. Caapanlan

GEOGRAPHIC oiroua- southern southern South circuit iust., oentral A south of south of DISTRIB. polar Gondwana Pacific Aoarlca, polar New Zeal. s.a. Aust. to°s A0°S continents continents margin New Zeal. continents New New Zeal, pale0 lat. paleolat. Antarctica Caledonia so. India, Hew New Guinea Madagascar, Caledonia, so. India so. South Australia America,

INFERRED changes In Gondwana Gondwana Gondwana Rengltata Gondwana Gondwana Gondwana Gondwana CAUSES circum- breakup, breakup breakup orogeny, breakup breakup, breakup, breakup, FOR Paciflc climate Gondwana clloate palaoclrc. paleoclrc. ISOLATION aobile change breakup change A paleoclla. A paleoclla. belts change change 6 6 2 assemblages. Forms endemic to the Austral Province were not

specifically identified by Scheibnerova, however. Instead, her

concept was based on the absence of Tethyan indicator taxa (including benthic species of the Orbitoidacea and planktonic species of the

Globotruncanacea) from marine sediments in central and southeast

Australia, New Zealand, peninsular India, Madagascar, and southern

South America. A warm, subtropical Transitional Province was also defined by Scheibnerova (1971, 1973) as being "intermediate in species composition" between the Austral and Tethyan Provinces. Like Webb (in

Hornibrook, 1969), Scheibnerova regarded latitudinal differences in climate as the primary cause for exclusion of Tethyan species from the extra-tropical provinces.

Sliter (1977) and Krasheninnikov and Basov (1983, 1986) applied

Scheibnerova's (1971, 1973) definition of the Austral Province in their discussion of Cretaceous planktonic foraminifer distributions in the high latitude Southern Hemisphere. These authors also noted the absence of indicator species of Pseudotextularia. Racecuembelina.

Planoglobulina. Ventrillabella. Pseudogeurabelina. Plunanerlta■

Trinitella. absence of nearly all species of Globotruncana and

Globotruncanita. and dominance of heterohelicids, hedbergellids, and rugoglobigerinids, Predominance of long-ranging species in the high latitude regions has caused considerable difficulties in cross- latitudinal correlation. 268

CAMPANIAN-MAASTRICHTIAN PLANKTONIC FORAMINIFER PALEOBIOGF.OGRAPHY

METHODS AND APPROACH

The geographic variations in total and keeled planktonic

foraminifer species diversity in the Southern Hemisphere are presented

for the early and late Campanian and the early and late Maastrichtian

in Figs. 41-43. These plots are based primarily on assemblages

recovered from deep sea sites with additional information from several

land-based sections. Paleolatitudes of each site, listed in Table 8,

were determined from recent paleogeographic reconstructions by Veevers

(1984) and Barron (1987). The site locations are plotted on

continental reconstructions (Figs. 42-43) modified after Smith et al.

(1981) for each time period. The species used as a taxonomic base for

this study were compiled from faunal lists of the various land-based

and deep sea reports from the Southern Hemisphere. These are presented, together with their paleolatitude ranges, in Appendix C.

Several factors contributing to inaccuracies in the species

diversity plots should be mentioned. First, local paleoceanographic and preservation factors may have influenced the taxonomic composition of assemblages of some sites. Faunas affected by dissolution or

current reworking lack the smaller, thinner walled components of their biocoenosis, leading to an underestimation of the total species diversity. In some cases, such as Site 364, only the keeled species diversity is reported since these forms are more resistant to dissolution and reworking. In contrast, keeled taxa may have been excluded from nearshore sequences, such as those of the Antarctic

Peninsula, because of their deeper life habitats. Sites where these 269

kind of biases are recognizable are noted in Table 8 with an asterisk.

Some faunal lists did not include foraminifers from the fine fraction

(<150 micron) residues, again causing an underestimation of the total

faunal diversity. Such cases are denoted in Table 8 with a cross,

A third form of bias is due to a lack of taxonomic uniformity

among different authors included in this report. For example, the number of species listed for the late Maastrichtian is nearly twice

the number listed for the early Campanian (Appendix C). This is caused more by the greater number of late Maastrichtian studies and differing taxonomic philosophies than an actual increase in species diversity. Consistency of identifications was evaluated only for sites where the planktonic faunas were illustrated. Nevertheless, the diversity plots are based on the diversity of morphotypes regardless of taxonomic nomenclature.

Finally, there is some inconsistency among different biostratigraphers in the way that the Campanian and Maastrichtian stages are differentiated and subdivided into early and late versus early, middle, and late ages. This lack of uniformity is largely caused by absence of age diagnostic species and magnetostratigraphic data from particular sections, and by ambiguities in the definitions of type sections. In order to achieve a more uniform definition of these four time intervals, the following criteria were used:

1) Early Campanian. Recognized based on correlation with the

Globotruncanlta elevata Partial Range Zone of Caron (1985); interval between the last appearance datum (LAD) of Globotruncana asymetrica

(Sigal) and the first appearance datum (FAD) of Globotruncana 270

ventricosa White or Globotruncanlta calcarata (Cushman). For high

latitude assemblages lacking these species, this time interval was

determined by correlation of species occurring above the LAD of

Mar g1notruncana pseudollnnelana Pessagno and co-occurrence with

calcareous nannoplankton species used to define the Marthasterites

furcatus Zone of Wise (1983).

2) Late Campanian. Recognized based on correlation with the

Globotruncanlta calcarata Total Range Zone of Caron (1985): interval

comprising the total stratigraphic range of G. calcarata (Cushman).

In the higher southern latitudes, this period of time is recognized by

the co-occurrences of Globlgerinelloldes imoensus Sliter and the

calcareous nannoplankton species Eifellithus eximius (Stover) and

Broinsonia oarca (Stradner).

3) Early Maastrichtian. Recognized based on correlation with the

Globotruncanella havanensis Partial Range Zone of Caron (1985):

interval, with Globotruncanella havanensis (Voorwijk), from the 1AD of

Globotruncanlta calcarata to the first appearance of Globotruncana aegyptiaca Nakkady. For sites where G. calcarata does not occur, this

interval was recognized based on occurrence of assemblages above the extinction of Eifellithus eximius and Broinsonia oarca and below the

first appearance of Rugotrueana circumnodifer (Finlay),

Globotruncanella petaloidea (Gandolfi), Globieerinelloldes subcarlnatus (Brdnnimann), or Abathomphalus spp.

4) Late Maastrichtian. Identified based on correlation with the

Abathomphalus mavaroensis Total Range Zone of Caron (1985): the

interval with the total range of Abathomphalus mavaroensis (Bolli). 271

For high southern latitude sites that lack this species, this interval

is identified based on the presence of Globotruneane11a petaloidea

(Gandolfi) or Globlgerinelioides subcarinatus (BrOnnimann).

The plots in Fig. 41 show broad latitudinal gaps in the number of sites occurring in the tropics, poleward of 65°S, and, in the

Campanian, between 35°S and 50°S. Furthermore, there are considerably fewer, data available for the Southern Hemisphere Campanian than there are for the Maastrichtian (see Table 8). Some sites that occur within the latitudinal gaps could not be used in this compilation because of obvious local facies influence on faunal distributions or incomplete faunal assemblage information. These stratigraphic and geographic gaps will probably remain until efforts are made to drill meridional transects along N-S trending continental margins in the polar regions.

FAUNAL PROVINCE DISTRIBUTIONS

Despite the limitations discussed above, important trends in Late

Cretaceous planktonic foraminifer distributions can be discerned in four time interval plots of total and keeled planktonic foraminifer species diversity for the Southern Hemisphere (Figs. 41-43). Analogy with modern planktonic foraminifer distributions suggests that differences in equator-to-pole diversity gradients for the early and late Campanian and the early and late Maastrichtian may reflect changes in the latitudinal positions of watermass boundaries and, perhaps, the distribution of Late Cretaceous climatic belts. B6

(1977) demonstrated that modern planktonic foraminifers show a sharp drop in species diversity between the 18°C and 10°C isotherms, TABLE 9. Canpaalao-Haaatrlchtian planlctoaic foraaialfaral spsolss diversity for Southarn Haalspbsra si tea. Huabar of kaalad spsclss la plottad in parentheses next to total auabar of spacias par site.

LOCATION EAftLI CAMPANIAN LATE CAMPANIAN EAHLT MAASTRICHTIAN LATE HA1STHI0BTIAN REFERENCES Palaolat. Sp. 01/. Palaolat. Sp. 01/. Palaolat, 3p. Olv. Palaolat. Sp. Dlv. <°3) Tot(Eld) (°S) Tot(Eld) (°S) Tot(Kld) (°3) Tot(Eld)

Pakistan 12 37(15). Hannah, 1992 Sita 3Sd, So. Atl. 22 (13)* 22 23(17) Caron, 1979 Sits 356, So. Atl. 33 30(1*) 33 32(17) 33 41(18) 33 49(27) Preaoli-Sllva A Boarsaa, 1977 Sita 516, So. Atl. 35 25(15) 35 29(13) 35 29(10) 35 53(17) Bains, 1994 Sita 357, So. Atl. 35 36(16) 35 *1 (2 6 ) Preaoll-Sllv* A Boarsaa, 1977 Sita 293, Pac. 0c. 35 12(9) 33 31(14) Hannah, 1982 31 India 39 10(5)* 35 24(9) 32 3K12) Oovlndan, 1972 Sita 217, Ind. 0c. *3 15(3) 39 28(11) Hannah, 1982 Sita 527, So. Atl. 41 30(14)* Boarsaa, 199* Sita 525, So. Atl. 42 30(16)* Boarsaa, 1984 Sita 524, So. Atl. 43 45(16) Saith A Poors, 1984 MW Australia *5 12(3) 45 23(7) Hannah, 1982 RV Australia 45 14(10) 45 20(7) Bright A Apthorps, 1976 M Australia 98 22(6) Hannah, 1982 ■■ W Australia 18 23(6) Hannah, 1992 Lord Hows Risa 49 13(2) Babb, 1973b N Australia 52 12(5) Hannah, 1982 W Australia 52 14(6)* Balford, I960 Sita 327, Pal/. PI. 5* 11(0) 54 12(1) Slitar, 1977 Sita 511, Falk. PI. 55 22(7) 55 15(0) 55 13(0) Erashennlnlitov A Basov, 1983 Maw Zealand 55 15(3) Babb, 1971 Sita 7*7, Narg. PI. 55 12(3) Qullty, pars, ooan., 19BB Sita 690, So. Atl. 56 12(1)* 56 13(3), This Study Sita TOO, So. Atl. 56 7(1)* 56 9(1) 56 14(3) This Study Sita 750, farg. PI. 57 (9)* 57 (1)* 57 CD* 57 12(5)* Qtiilty, pars, coaa., 1988 Sita 733, EarS. PI. 61 14(4) This Study Antarctic Peninsula 64 12(1)* 64 10(0) Hubar, 1998 Sita 609B, Haud Risa 64 12(0) 64 17(5) This Study Sita 690C, Maud Risa 65 12(0) 65 17(5) This Study

*Faunal distributions sffaotad by Local baainal conditions or poor preservation. *Ineonplate fauna! lists. 272 Figure 41. Diversity plots of total (squares) and keeled (crosses) planktonic foraminiferal species diversity in the Southern Hemisphere for the early and late Campanian and the early and late Maestrichtian. The boundaries between the Late Cretaceous Southern Hemisphere biogeographic provinces are designated by a dashed line. Sites listed in Table 8 have been adjusted to their Late Cretaceous paleolatitudes.

273 EARLY CAMPANIAN 10 ’ LATE CAMPANIAN t so- 1

so Tethyan 1 s Transitional SOI Tethyan Auatral 1 | Province Province «l ^ Province Province V u **' 1 £ a. V (/i VICL 1 * O 30- O 30 ° 1 I 1 = a « 1 * hD D1 e Q 20 - §20* 1 s z ■ 1 m 1 10 i °o 1° 1 □ a

10 20 30 «0 50 60 70 9 0 eo 10 20 JO 40 SO 60 70 flO 90 Degrees Soulh PoJeolotilude Degrees Soulh Paleolatitude

EARLY MAASTRICHTIAN LATE MAASTRICHTIAN I I Ml u 50 Tethyan £ > Auatral 50 Tethyan L I Austral O h* Jl §1 Province a Province Province 0 «1 Province 4) v 1111 t/la a \ l £ l o 30 O 3 0 o 1 I § 20 20 h z E 0 I db ■1 o l» o “ 10 10 ■

I- J ° 4 7 2 -I ■ I* 'T 20 30 40 50 60 70 10 20 30 40 50 60 70 60 90 Degrees Soulh Paieolalilude Degrees Soulh Poleoiptilude

Figure 41. Figure 42. Paleogeographic reconstruction showing continental and land-sea distributions for the early and late Campanian. Areas inferred to be above sea level are shown by the stippled pattern. Planktonic foraminifer species diversity is plotted according to paleolatitude positions of sites listed in Table 8. Inferred paleobiogeographic boundaries between the Tethyan, Transitional, and Austral Provinces are delimited by dashed lines. Continental distribution data from Smith et al. (1981) and Veevers (1984). Information on land-sea distributions in Antarctica based on the sublacial topography map of Drewry (1983) and paleobiogeographic distributions discussed in the text. Other land-sea distributions based on the reconstruction for the early Maastrichtian from Barron (1987).

275 ao-iB ■ «o 1 \ -1 «ao ■

► ► paolaa B teale k lan P lntno y a . l a a p . Planhtonlo laat \ Dlvaralty iue 42. Figure laat , Dlvaralty |Sltionai 276 Figure 43. Paleogeographic reconstruction showing continental and land-sea distributions for the early and late Maastrichtian. See Fig. 42 for additional information.

277 AL MAASTRICHTIAN EARLY

► ► Spaalaa Planktonic 10-14 >14 Planktonic S p ac|o a i a ac|o p S Planktonic • ao Figure 43 Figure 30-3S a i - O i ' 0 / 30* A' laat ' Dlvaralty {„ „ { 1 / o Kao Spaoloa Kaalod Ho. oa Sala Ho. Spaoloa Total k IA1 k \ N ' r i \V \

■A '■ 278 279 which delimit the Subtropical and Subpolar Provinces. This biogeographic boundary occurs between about 38° to 50° latitude today

(B6, 1977). If Cretaceous species distributions reflect the arrangement of paleoclimatic belts as they do in modern seas, then poleward shifts in total and keeled species diversity may reflect significant warming events.

Previous reviews of the Late Cretaceous distributions of planktonic foraminifers in the Southern Hemisphere lacked data from the late Maastrichtian in polar regions. In addition, no species were determined to be endemic to any of the defined biogeographic provinces. In light of the new information from the high latitude deep sea sites, a more concise portrayal of the Campanian through

Maastrichtian provincial boundaries and characteristic taxa is now possible.

Early Campanian

The latitudinal diversity plot for the early Campanian (Fig. 41) shows a low poleward diversity gradient relative to the other graphs.

Bicarinate species were abundant in the high latitudes during the early Campanian (Fig. 41, 42), with seven species occurring at the

DSDP Site 511 on the Falkland Plateau (Krashenninikov and Basov, 1983) and six species occurring in Western Australia (Edgell, 1957; Belford,

1960). Early Campanian total diversity values at Site 511, which was located at 55°S paleolatitude, are close to the total number of species reported at DSDP Site 516 on the Rio Grande Rise, which was located at about 35°S paleolatitude. The low number reported for Western 280

Australia (Table 8) results from an incomplete listing of smaller planktonic foraminifers in Belford's (1960) report.

Species composition at all South Atlantic and Western Australia sites is similar, with no endemic species recognized. Therefore, all planktonic faunas poleward of about 42°S paleolatitude are included in the Transitional Province, and an early Campanian Austral Province is not recognized (Figs. 41, 42). The planktonic foraminifer distributions indicate the presence of broad latitudinal climatic zones, and perhaps, quite warm polar temperatures. Paleotemperature studies of belemnites from New Zealand (Stevens and Clayton, 1971) and planktonic foraminifers from the western equatorial Pacific

(planktonic foraminifers) (Douglas and Savin, 1975) are consistent with this interpretation.

Late Campanian

Total and keeled species diversity diminished considerably at all high southern latitude sites during the late Campanian, and the poleward diversity gradient increased significantly (Figs. 41, 42;

Table 8). At the Falkland Plateau, total diversity dropped from 22 species during the early Campanian to 15 species during the late

Campanian, and diversity of keeled species decreased to zero.

G1obo t rune ana linneiana (d'Orbigny) is the only keeled planktonic species in the southern South Atlantic region at this time. This species occurs in low abundance at ODP Site 700, but it has not reported from the upper Campanian on the Falkland Plateau. With the diminished occurrence of G1ob o t rune ana during the late Campanian, the 281 high latitude assemblages become dominated by species of Heterohelix.

Globigerinelloides. Hedbergella. and especially Archaeoelobigerlna

(see Chapters III and IV).

Two species endemic to the Austral Province, Archaeoglobleerina australis n. sp. and Globigerinelloides lmoensus Sliter, first appeared during the late Campanian. australis is a dominant component of upper Campanian-Maastrichtian planktonic foraminifer assemblages throughout the southern South Atlantic region, but it has not been recognized elsewhere (Chapters III, IV). G. lmoensus occurs in upper Campanian-lower Maastrichtian sections in the southern South

Atlantic region (Chapters III, IV; Sliter, 1977; Krasheninnikov and

Basov, 1983)) and in upper Campanian sediments of ODP Site 750 in the southern Indian Ocean (P. Quilty, pers. comm., 1988).

In the South Atlantic, northward limit of the Austral Province during the late Campanian is defined at about 48°S paleolatitude based on the southern South Atlantic distribution of Archaeoelobigerlna australis and Globigerinelloides impensus and the nearly complete absence of ornate and keeled planktonic taxa from the polar areas.

The Transitional Province is inferred to occur between 38°S and 48°S during the late Campanian (Figs. 41, 42), but data are lacking for this latitudinal belt. The paleobiogeographic boundaries discussed are also inferred for the South Pacific Ocean, but data is lacking

Early Maastrichtian

As during the late Campanian, the early Maastrichtian diversity gradient was quite high, changing from 30 to 40 total species and 10 282

to 18 keeled species in the middle latitudes to 13 or fewer total

species and one or no keeled species in the high southern latitudes

(Figs. 41, 43; Table 8). # Assemblages are dominated by.^imple,

globulose planktonic species, and marker species are completely

absent.

Endemic taxa that first appear in lower Maastrichtian sections within the Austral Province and range through the late Maastrichtian

include Archaeogloblgerina mateola n, sp. and Hedbergella sllterl n.

sp. A. mateola occurs at the Maud Rise and northeast Georgia Rise

deep sea sites and in the James Ross Island region, but this species has not been found at the Falkland Plateau or outside the southern

South Atlantic region (see Table 5 in Chapter IV). Ji. sllteri is more useful to define the northern limits of the Austral Province as it

occurs at all southern South Atlantic sites and it also occurs in the

southwest Pacific Ocean.

Late Maastrichtian

The late Maastrichtian is characterized by an an increase in total and keeled species diversity and migration of several keeled taxa into

the polar regions (Figs. 41, 43; Table 8). Keeled specimens of

G1obo t runc ana area (Cushman), G1ob o t rune ana subcircumnodifer

(Gandolfi), Rugotruneana circumnodifer (Finlay), Abathomphalus

intermedius (Bolli), and Abathomphalus mavaroensis (Bolli) comprise a

significant proportion of assemblages from the Maud Rise, Northeast

Georgia Rise, and the Kerguelen Plateau (see Chapters III, IV).

Abathomohalus spp. and G, subcircumnndf fer were previously thought to 283 be restricted to the Tethyan Province (Douglas, 1969; Sliter, 1977), but the subsequent recovery of upper Maastrichtian sediments in the higher latitudes expanded their known biogeographic ranges. An earlier suggestion that species of Abathomphalus were excluded from the polar regions (Sliter, 1977) was based on an incorrect age assignment for the youngest Cretaceous sediments at the Falkland

Plateau (Fig. 27, Chapter III).

The southern limits of the Tethyan and Transitional Provinces are inferred to have moved poleward during the late Maastrichtian (Figs.

41, 43) based on the occurrences of several low latitude indicator species at 65°S at the Maud Rise and Site 738 on the Kerguelen Plateau.

The species Hedbereella sliteri. Archaeogloblgerina australis. and

Archaeogloblgerina mateola continued to be restricted to the Austral

Province during this time. Rugotruneana circumnodifer first appeared just prior to the late Maastrichtian. The distribution of this species extends from the southwest Pacific region (New Zealand and

DSDP Site 208 in the Tasman Sea) to the southern South Atlantic, including all the Maud Rise and northeast Georgia Rise ODP sites.

The late Maastrichtian poleward gradient remained high for both total and keeled species diversity, as shown on Fig. 41. Tethyan planktonic foraminifer assemblages show total diversity values as high as 53 species and keeled diversity of up to 27 species, whereas assemblages from the high latitudes show total diversity values of 17 or fewer species and keeled diversity values of five or fever species

(Table 8). Abrupt drops in diversity at about 44°S and 52°S (Fig. 41) 284

are the basis for inferring the northern limits of the Transitional

and Austral Provinces, respectively.

COMPARISON WITH NORTHERN HEMISPHERE ASSEMBLAGES

The poleward changes in Late Cretaceous planktonic foraminifer

distributions have been studied for North America (Douglas, 1969) and

the eastern margin of the Pacific Ocean (Sliter, 1972). Both authors

had limited information from the Campanian and early Maastrichtian

high northern latitudes, and no high latitude data for the late

Maastrichtian. Nevertheless, poleward trends similar to those

described for the Southern Hemisphere were recognized. Douglas (1969)

reported that taxonomic diversity during the Campanian decreased most

rapidly north of about 40°N. The Boreal Province faunas of the

Campanian and Maastrichtian were characterized by both authors as

having low species diversity and few keeled taxa. Douglas (1969)

noted that single keeled globotruncanids reached 60°N during the early

Campanian, but extended no further than 40°N by the early

Maastrichtian. In addition, Douglas (1969) suggested that double

keeled taxa were completely excluded from northern polar environments

during the early Maastrichtian, Sliter (1973) reported two double

keeled species from lower Maastrichtian sediments at Vancouver Island

(50°N). No endemic species of planktonic foraminifers were recognized

in the Boreal Province during the Campanian-Maastrichtian time.

Other studies from the North American high latitudes include

reports of Late Cretaceous foraminifers from nearshore biofacies, where some or all planktonic foraminifers are excluded. Campanian- 285

Maastrichtian planktonic foraminifers from Saskatchewan (North and

Caldwell, 1970) and Manitoba (McNeil and Caldwell, 1981) Include only species of Heterohelix. Globigerinelloides. and Ruglobieerlna. but no globotruncanids. Moreover, Arctic North Slope foraminifer assemblages are almost completely barren of planktonic foraminifers (Tappan, 1957;

McDougall, 1987).

Deep-sea cores with Maastrichtian microfossils were recovered from a site located at 66°N in the central Arctic Ocean (Clark, 1982),

However, the sediments contain no significant carbonate components. instead containing high percentages of biogenic silica and lacking evidence of bioturbation. Kitchell and Clark (1982) suggested that the sediments were deposited in a deep basin during periods of high primary productivity and intense upwelling. Thus, there is little chance that a foraminifer record will be obtained from this region.

So far, no Upper Cretaceous foraminifers have been recovered from marine sediments in Greenland, Ellesmere Island or surrounding islands in that region (H.J. Hansen, pers. comm., 1988)

The Maastrichtian planktonic foraminifer record reported from

Denmark and southern Sweden (Berggren, 1962) is quite diverse and enriched in single and double keeled species, despite the relatively high paleolatitude (52°N-60°N) and shallow water setting of that area.

Eight species of G1obo t rune ana and two species of Globotruncanita were recorded in Berggren's study. The greater diversity can be attributed to influence of warm, Tethyan waters carried well into northern

Europe. 286

Little information is available on the distribution of Late

Cretaceous planktonic foraminifers in northern Russia. Subbotina

(1971) reported the occurrence of several keeled planktonic species in

the Caucasus Mountains region (40°-45°N) , but only G1ob o trune ana

contusa was mentioned as occurring as far north as the Ural Mountains

(51°N). No mention of higher latitude occurrences of Upper Cretaceous

planktonic foraminifers were mentioned by Subbotina, however.

NEARSHORE BENTHIC FORAMINIFER PALEOBIOGEOGRAPHY

Shelfal assemblages of benthic foraminifers included in the

Austral Province have been characterized by the predominance of

agglutinated taxa, low diversity of calcareous benthic assemblages and

absence of larger foraminifers, such as the Orbitoididae and

Amphisteginidae (Scheibnerova, 1971; Webb, 1971). In addition, palmate nodosarids and species of Gaudrvina. Dorothia. and

Bolivinoides are conspicuously absent or present in low diversity.

Deep sea benthic assemblages are not considered useful in identifying the Austral Province, since their habitats were beyond the influence of the seasonally changing surface environment.

Biostratigraphic schemes proposed for the Upper Cretaceous of several nearshore, extra-tropical basins include both benthic and planktonic zonal taxa (Fig. 44). Diachroneity or abbreviated stratigraphic ranges of several of the benthic zonal species, such as

Gaudrvina healyi. suggest that their distribution is facies controlled and their biostratigraphic value is limited In inter-regional correlations (Huber, 1988). Figure 44. Biostratigraphic zonal schemes for Upper Cretaceous nearshore sites in New Zealand, southern South America and the Antarctic Peninsula. HJebb, 1971; 2Bertels, 1979; 3Malumlan and Masiuk, 1976; *Huber, 1988.

287 NEW ZEALAND ARGENTINA ANTARCTICA NEUOUIN BASIN HAQALLANES BASIN JAMES ROSS BASIN European L o c a l E u r o p e a n E u r o p e a n local European ZOA*' Z o n e 1 Z o n e 1 Z o n p 4 SUfl* S t a g e S t a g e S t a g * Stage S t a g e i nil ni mi

v S§ 1K I III < < O* o § £ 2 2 < II 2 o S * 3 ■3Sj 3 5 u 2 5 ° 3 9 * o 2 Q * ID Q£ 1! * x 1 X < u < 2 < o C 9 H x u X 2 r aI u •» o i u5 N 3 a * « < e* Q § 3

Figure 44. 288 289

Table 9. Distribution and age ranges of benthic foraminifers restricted to several localities within the Austral Province.

Spedea Mama* Age Rang** Relerencea

Cydammina d campianata Law Cam pan an to Maattnchban Maw Zealand (Webb. 1971) Chapman Mklde

Gaudryina h—fyi Finlay Lata Campanian to Meattriehtian N m Zetland (Wabb. 1971) EartyC?) to lata Maattrichtan Lord Howa Rita (Wabb, 1973b) Lata Campanian Jamat Rota Itland region (Hubor and Webb, 1966; blit ttudy) Earty Meattriehtian Southern Argentina (Matoman and Matiuk, 1976)

Domthm elongate Finlay Lata Campanian to lata Maaatrichtian New Zealand (Webb. 1971) Earty (?) to lata Maattrichban Lord Howa Rite (Wabb. 1973b) Middla(?) to lata Campanian Jamat R ott Itland region (Huber and Webb, 1966; tois ttudy)

Kamnpta aagra Finlay Lata Campanian to lata Maaatrichtian Naw Zealand (Wabb. 1971), Jamee Rots Itland region (Huber and Wabb, 1986; (hit ttudy)

Ftondcuiaria mkmtzoana Lata Maattnchban Naw Zealand (Wabb. 1971) (Finlay) Earty(7) to lata Meat tnch sen Lord Howa Rita (Wabb. 1973b) Lata Campanian to party Maaatridtban Jamat Rott Itland region (Huber and Wabb. 1966; Iti'n ttudy)

BuHminaHa crtta (Finlay) Lata Campanian to lata Maaatrichtian Jam at R ott Itland region (Huber and Webb. 1966; tort ttody) Paiaoeana Naw Zealand (Webb. 1971), Lord Howa Rite (Webb, 1973b)

BoMvtnotdat draco (Mariton) Law Maattnchban New Zealand (Webb. 1971), Lord Howa Rita dormant Finlay (Webb. 1973b), Soudiam Chile (Charrier and Lahten, 1969)

Afabamma crata (Finlay) Lata Campanian to law Maattrichtian Naw Zealand (Wabb, 1971), Jamet Rott Itland region (Huber and Wabb. 1996; that ttudy) Earty (?) to law Maattnchban Lord Howa Rita (Wabb. 1973b) 290

Benthic species apparently confined to the Austral Province during

the late Campanian-Maastrichtian are listed on Table 9. Huber and

Webb (1986) extended the paleobi>geographic range of Frondicularia

rakauroana (Finlay) from the southern southwest Pacific (New Zealand and Lord Howe Rise) to Seymour Island (Antarctic Peninsula). The agglutinated species Dorothia eloneata (Finlay) and Gaudrvina healvl

Finlay were also reported from these three sites (Huber, 1988). The additional occurrence of G. healvi in Tierra del Fuego was reported by

Malumian and Masiuk (1976).

The oldest reported occurrences of the agglutinated genus

Ovclflm m ina are from high southern latitude sites. Cvclam niin« cf. C. complanata Chapman occurred in nearly all of the upper Campanian-

Maastrichtian samples studied from the James Ross Island region

(Huber, 1988). It occurs in slightly younger Cretaceous nearshore sediments from the Burdwood Bank (Macfadyen, 1933), and New Zealand

(Webb, 1971), and In shelf sediments of late Paleoeene age in southeast Australia (Ludbrook, 1977). However, cyclamminids have not been reported In sediments older than the latest Paleoeene in lower latitude regions. This not only testifies to the high latitude origin of this genus, but also reflects its migration from shallow to deep water environments, as this taxon is rarely present above bathyal and abyssal depths in modern oceans (Akers, 1954).

Several species have only been recovered from Campanian-

Maastrichtian sediments in the James Ross Island region and New

Zealand. These Include Karrerlella aegra Finlay, Bulimlnella creta

(Finlay), and Alabamina creta (Finlay). None of the taxa listed In 291

Table 9 have been reported from the Late Cretaceous Neuquen Basin of southern South America (Bertels, 1979), Magallanes Basin of southern

Chile (Lahsen and Charrier, 1968), or southeastern Australia (Taylor,

1964). Nevertheless, the widely separated occurrences of these species raise the possibility that they will eventually be found throughout the southern basins, including subglacial basins identified within Antarctica.

INFERRED PATTERNS OF SURFACE CIRCULATION

Late Cretaceous positions of foraminifer biogeographic province boundaries are considered to have been controlled primarily by oceanic surface circulation patterns and gyre configurations (Sliter, 1977).

On this basis, analyses of biogeographic patterns of diversity and endemism for Campanian through Maastrichtian time can be used to reconstruct paleocirculation patterns of surface waters in the

Southern Hemisphere oceans (Fig. 45). Only one map is produced as a summary for the whole Campanian-Maastrichtian interval, as sample coverage and paieoenvironmental data are insufficient to enable more detailed time interval reconstructions.

The revised reconstruction of Antarctic paleogeography, discussed earlier in this chapter, allows for the presence of shallow marine seaways through much of West Antarctica. This would have enabled faunal communication from New Zealand along the southern margin of the

Pacific Ocean, across West Antarctica to southern South America (Fig.

45). Paleobiogeographic evidence for this faunal dispersal route is based on similar taxonomic affinities among a number of shelfal macro- 292

f Inferred surface circulation

Figure 45. Inferred patterns of surface circulation for the Southern Hemisphere during the Campanian through Maastrichtian. See Fig. 42 for explanation of paleogeographic reconstructions. 293 invertebrate (Zinsmeister, 1979; 1982; Macellari, 1985, 1987) and microfossil groups (Huber and Webb, 1986; Huber, 1988; Askin, 1988).

Uniformity in species distributions during the early Campanian suggests that a southern South Atlantic gyre did not exist at that time, but data are insufficient for further speculation. The configuration of oceanic gyres shown on Fig. 45 in the South Atlantic is inferred from the positions of late Campanian through late

Maastrichtian foraminifer province boundaries. The boundary between the Tethyan and Transitional Province, from about 35°S to 45°S (Fig.

45), is marked by a decrease in total and keeled planktonic foraminifer diversity, but not by the presence of endemic species.

Thus, a tropical-subtropical gyre is inferred to be well defined in the northern South Atlantic, but more diffuse with increasing latitude southward. The boundary between the Transitional Province and Austral

Province, between about 45°S to 50°S, is well constrained in the South

Atlantic Ocean based on the distribution of planktonic foraminifers.

The southern limit of a subtropical gyre is inferred to pass along the nothern edge of the Falkland Plateau and eastward, while a subantarctlc gyre is inferred to flow northward along the Antarctic

Peninsula to the Falkland Plateau and then eastward. Weak circumpolar flow is judged to continue eastward toward the Kerguelen Plateau from the southern South Atlantic Ocean (Fig. 45).

Influence of warmer water currents on foraminifer assemblages in western Australia is suggested by the moderate abundance of keeled planktonic foraminifers throughout the Campanian-Maastrichtian

(Edgell, 1957; Belford, 1960; Hannah, 1982). A broad tropical to 294

subtropical gyre is shown in the Indian Ocean and surrounding

Madagascar based on reports of Tethyan and Transitional Province

species in those regions (Govindan, 1972; Hannah, 1982).

The southern South Pacific Ocean was probably dominated by a very

broad counter-clockwise gyre with a western boundary current flowing

southward along the southern and eastern margin of Australia and past

the eastern and western margins of New Zealand. Shelfal marine

passages are inferred to allow penetration of surface currents through

West Antarctica and the Antarctic Peninsula. An eastern boundary

current is surmised to have flowed northward along the west coast of

South America.

Several factors may have influenced surface circulation and biotic

interchange in the high southern latitude region during Campanian-

Maastrichtian time. These include:

1) Tectonic activity in the Antarctic Peninsula region. Orogenic activity and episodes of volcanism are known to have occurred throughout the Late Cretaceous in the northern Antarctic Peninsula (Farquharson, 1982; Elliot, 1983; Macellari, 1988). Insufficient information is available to determine the extent of land connection from the Antarctic Peninsula region to southern South America during this time, but the presence of fossil wood (Francis, 1986) indicates that significant areas were above sea level. Episodes of intense tectonic activity may have periodically shut off shallow water flow between the southeastern Pacific and southern South Atlantic basins, resulting in biogeographic isolation of shallow marine organisms in the northern Antarctic Peninsula and southern South America.

2) Sea level changes. If this were an important factor, major eustatic rises in sea level would have enhanced communication across the West Antarctic shelf, whereas eustatic falls would have shut off faunal communication. However, too little data are available to evaluate the effects of sea level changes on the patterns of paleobiogeographic dispersal in the high southern latitudes.

3) Continental drift. Although New Zealand occupied a polar position throughout the Late Cretaceous, it underwent a rapid northward migration from about 80°S at 95 Ma (Oliver et al., 1979) to 295

62°S by 75 Ma (Grindley et al., 1977). This continental dispersal led to diminished taxonomic similarities between Maastrichtian and early Tertiary shallow marine bivalves and gastropods of the James Ross Island and New Zealand (Zinsmeister, 1979, 1982), but it seems to have had little effect on foraminifer distributions. Occurrence of Hedbereella sliteri and Rupotruncana circumnodifer in both regions attests to continued biotic dispersal between these areas through the late Maastrichtian. Rifting between the margins of southern Australia and East Antarctica beginning at about 95 Ma (Veevers, 1984) and inception of shallow water flow between those areas may also have influenced Austral Province distributions, but no effect can be discerned from the foraminifer distributional data.

Inability to correlate Campanian-Maastrichtian foraminifer distribution trends with any tectonic or eustatic events described above either speaks for a constancy in shelfal marine communication along the circum-Pacific margin or, more likely, points to a poor understanding of factors controlling the foraminifer distributions in the high southern latitude regions. Much more information is needed to further advance our understanding of circum-Antarctic paleoceanography during the Late Cretaceous.

CONCLUSIONS

Latitudinal changes in total and keeled species diversity and taxonomic compositions of Upper Cretaceous planktonic foraminifers in the Southern Hemisphere are presumed to reflect variations in the vertical stratification of surface waters, the distribution of paleoclimatic belts and oceanic surface circulation patterns.

Analysis of the Campanian-Maastrichtian time interval shows a rapid decrease in diversity at about 40°S during the early Campanian, about

35°S during the late Campanian and early Maastrichtian, and about 40°S during the late Maastrichtian. The extra-tropical Austral Province Is 296 not discernable during the early Campanian, but it is defined for the late Campanian and early and late Maastrichtian by the first occurrence of several endemic taxa, low species diversity, and nearly complete exclusion of keeled planktonic morphotypes. The northern boundary of this province is inferred to be about 48DS during the late

Campanian, 50°S during the early Maastrichtian, and 52°S during the late Maastrichtian.

The early Campanian planktonic foraminifer distributions represent the broadest expansion of the tropical climatic belt and perhaps the warmest paleotemperatures of the Campanian-Maastrichtian time period.

Increase in latitudinal taxonomic gradients during the late Campanian and early Maastrichtian suggests equatorward contraction of the

Tethyan Province and higher equator-to-pole thermal gradients. Nearly complete absence of keeled morphotypes from Austral Province sites during that time indicates poor surface water stratification in the polar regions. Migration of keeled species into the Austral Province during the late Maastrichtian suggests an episode of high latitude warming, resulting in reduced equator-to-pole thermal gradients and more stratified high latitude surface waters.

Recognition that shallow seas may have covered broad areas of the present Antarctic continent helps explain the equable climates that characterize the Cretaceous Period. The lower land-sea ratio results in a reduced surface albedo on the polar continent. Furthermore, a single, broad gyre system operating in the Pacific Ocean would have brought warm, equatorial waters into the continental interior of 297

Antarctica. Moisture laden air carried to the high latitudes would have been an additional cause for warmer polar temperatures.

The inferred Antarctic seaways would also have provided avenues for migration of nearshore, southern circum-Pacific benthic invertebrates, in addition to planktonic organisms. This would explain similarities in the distribution of Upper Cretaceous bivalves, gastropods, and ammonites included in the macrofossil Ueddellian

Province (Zinsmeister, 1982; Macellari, 1985, 1987) and shallow water benthic foraminifers included in the Austral Province. Except for its restriction to shallow marine facies, the limits of the Ueddellian

Province strongly parallel the boundaries of the planktonic foraminifer Austral Province.

Changes in the positions of the Late Cretaceous biogeographic provinces in the Southern Hemisphere were probably related to a complex interrelationship of eustatic fluctuations in sea level, major climatic changes, continental migrations resulting from the breakup of

Gondwana, and changes in surface circulation patterns. Isolation of

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314 APPENDIX A Counts ot lereminiters from (he > 150 moron size (rad o n tor all samples studied. See 689.

ODP SITE 689

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APPENDIX E. Southern Hemisphere planktonic foraminifers reported for the Campanian-Maastrichtian of the Late Cretaceous. Paleolatitudes for each reported occurrence are shown in parentheses and are listed with references on Table 8.

Early Campanian

Heterohelix globulosa (Ehrenberg) (33,35,52,55) Heterohelix globocarinata (Cushman) (33) //eteroftelix papula (Belford) (52) Heterohelix pulchra (Brotzen) (33,35,55) Heterohelix punctulata (Cushman) (33) Heterohelix reussi (Cushman) (35,55) Heterohelix striata (Ehrenberg) (33,35,52) Heterohelix planata (Cushman) (55) Gublerina sp. (33) Pseudogeumbelina costulata (Cushman) (33) Pseudotextularia elegans (Rzehak) (33,35) Ventilabre11a eggeri (Cushman) (35) Globigerlnelloides asperus (Ehrenberg) (52,55) Globigerinelloides bollii (Pessagno) (33,55) Globigerinelloides pauccensis (33) Globigerinelloides multispinatus (Lalicker) (55) Globigerinelloides volutus (33) Shackoina multispinata (Cushman & Wickenden) (33,55) Hedbergella loetterli (Nauss) (55) Hedbergella crassa (Bo111) (55) Hedbergella sp. (55) Loeblichella hessi (33) Whitenella baltica (Douglas & Rankin) (55) Archaeoglobigerina blowi (Pessagno) (33,35,55) Archaeoglobigerina cretacea (d'Orbigny) (33,52,55) Costellagerina bulbosa (Belford) (52) Costellagerina pilula (Belford) (33,52) Rugoglobigerina rugosa (Plummer) (33,35) Marginotrunctta marginata (Reuss) (52,55) Marginotzuncana renzi (Gandolfi) (35) Globotruncana area (Cushman) (33,35,55) Globotruncana asymetrica (Sigal) (35) Globotruncana bulloides (Vogler) (33,35,52,55) Globotruncana calciformis (Vogler) (33) Globotruncana coronata (White) (35) Globotruncana concavata (Barr) (35) Globotruncana fomicata (Plummer) (33,35,57) Globotruncana globlgerinoides (52,55) Globotruncana hilli (Pessagno) (33) Globotruncana lapparenti (Brotzen) (33,52,57) Globotruncana leuopoldi (33) Globotruncana linneiana (d'Orbigny) (33,35,55) Globotruncana oblique (Herm) (35) Globotruncana paraconcavata (Porthault) (35) Globotruncana plunmerae (Gandolfi) (33,55) 324

Globotruncana pseudolinneianna (Pessagno) (35) Globotruncana rosetta (Carsey) (33) Globotruncana sinuosa (Porthault) (35) Globotruncana stephensoni (Pessagno) (35) Globotruncana subspinosa (Pessagno) (35) Globotruncana crlcarinata (Quereau) (33,52) Globotruncana undulata (Lehmann) (35) Globotruncana ventricosa (White) (35,52) Globotruncanlta elevata (Brotzen) (33)

Late Campanian

Heterohelix glabrans (Cushman) (54,55,56,64,65) Heterohelix globocarinata (Cushman) (33) Heterohelix globulosa (Ehrenberg) (32,33,35,54,55,56,64,65) Heterohelix planata (Cushman) (35,52,55) Heterhelix pseudotessera (35) Heterohelix pulchra (Brotzen) (33,35,52,54,55,56,64,65) Heterohelix punctulata (Cushman) (33) Heterohelix rumseyensis (Douglas) (55) Heterohelix striata (Ehrenberg) (35,52) Heterohelix ultimatumlda (White) (32) Pseudogeumbelina costulata (Cushman) (35) Pseudoguembelina kempensis (Esker) (35) Gublerina robusta (Stenestad) (35) Gublerina cuvillieri (Kikoine) (35) Pseudotextularia elegans (Rzehak) (33,35) Planoglobulina carseyae (Plummer) (35,54,55) Planoglobulina multicamerata (de Klasz ) (35) Planoglobulina riograndensis (Martin) (35) Globigerinelloides asperus (Eherenberg) (55) Globigerinelloides bollii (Pessagno) (55) Globigerinelloides impensus (Sliter) (55,55,57,64,65) Globigerinelloides multispinata (Lalicker) (52,54,55) Globigerinelloides paucaensis (33) Globigerinelloides prairiehillensis (Pessagno) (52) Globigerinelloides volutus (White) (33) Schackoina multispinata (Cushman & Wickenden) (33,54,55,56,64.65) Hedbergella crassa (Bolli) (55) Hedbergella holmdelensis (Olsson) (52,54,55,64,65) Heterohelix monmouthensis (Olsson) (54,55,64,65) Hedbergella loetterli (Nauss) (55) Hedbergella sp. (55) Archaeoglobigerina australis n. sp. (54,55,56,64,65) Archaeoglobigerina blow! (Pessagno) (35,55) Archaeoglobigerina cretacea (d'Orbigny) (33,52,55) Rugoglobigerina hexacamerata (Brbnnimann) (33) Rugogloblgerina pustulate (BrOnnimann) (54) Rugoglobigerina rugosa (Plummer) (32,33,35,52) Globotruncana area (Cushman) (33,35) 325

Globotruncana asymetrica (Sigel) (35) Globotruncana bulloides (Vogler) (33,35,52) Globotruncana calciformis (Vogler) (33) Globotruncana coronota (Bolli) (55) Globotruncana fomicata (Plummer) (33,35,39) Globotruneana billi (Pessagno) (33) Globotruncana lapparenti (Brotzen) (39,33) Globotruncana leupoldi (Bolll) (33) Globotruncana linneiana (d'Orbigny) (33,35,52,55) Globotruncana marlei (Banner & Blow) (35) Globotruncana obliqua (Hemi) (35) Globotruncana plummerae (Gandolfi) (33,55) Globotz-uncana psuedolinnieana (Pessagno) (55) Globotruncana rosetta (Carsey) (33,35) Globotruncana stephonsoni (Pessagno) (35) Globotruncana stuartiformls (Dalbiez) (35,39) Globotruncana subcircuumodifer (Gandolfi) (39,33) Globotruncana subspinosa (Pessagno) (33) Globotruncana scutilla (35) Globotruncana tricarinata (Quereau) (33,39) Globotruncana ventricosa (White) (33,35,52) Globotruncanita calcarata (Cushman) (33) Globotruncanlta elevata (Brotzen) (33) Globotruncanella havsmensis (Voorwijk) (33,35,39)

Early Maastrlchtlan

Guembelitria cretacea Cushman (45,56,64,65) Heterohelix glabrans (Cushman) (35,39,54,56,64,64,65) Heterohelix globocarinata (Cushman) (33) Heterohelix globulosa (Ehrenberg) (33,35,35,35,39,45,54,56,64,64,65) Heterohelix navarroensis (Loeblich) (33,35) Heterohelix pseudotessera (35) Heterohelix pulchra (Brotzen) (33,35,35,35,39,45,45,54,56,64,64,65) Heterohelix punctulata (Cushman) (33,35) Heterohelix striata (Ehrenberg) (33,33,35,35,35,39,45,45) Heterohelix ultumitumida (White) (33,35,39) Gublerina cuvillieri (Kiklone) (35,35,39,45,45) Gublerina robusta (de Klasz) (33,35,35) Pseudoguembelina costulata (Cushman) (33,33,35,35,35,39) Pseudoguembelina excolata (Cushman) (33) Pseudoguembelina kempensis (Esker)(35) Pseudotextularia defonnis (Kikoine) (33,35,39) Pseudotextularia elegans (Rzehak) (33,33,35,35,39,45,45) Pseudotextularia varians (Rzehak) (35,39) Planoglobulina acervulinoides (Egger) (33,33,35,35,39) Planoglobulina carseyae (Plummer) (35,35,35,54) Planoglobulina multicamerata (de Klasz) (33,33,35,35,39) Planoglobulina riograndensis (Martin) (35) Globigerinelloides multispinata (Lalicker) (33,35,39,45,54,56,64,64,65) 326

Globigerinelloides pauccensis (33) Globigerinelloides prairiehillensis (Pessagno) (33,35,39,45) Globigerinelloides subcarinatus (BrOnnimann) (33,33,39) Globigerinelloides volutus (White) (33,35) Globigerinelloides yacoensis (35) Scbackoina multispinata (Cushman & Wickenden) (33,54,56,64,64,65) Hedbergella homdelensis (Olsson) (35,45,56,64,65) Hedbergella monmouthensis (Olsson) (45,54,56,64,64,65) Hedbergella sliteri n. sp. (54,56,64,64,65) Archaeoglobigerina australis n. sp. (54,56,64,64,65) Archaeoglobigerina blowi (Pessagno) (35,35) Archaeoglobigerina cretacea (d'Orbigny) (33,35) Rugoglobigerina hexacamerata (BrOnnimann) (33,35,35,35) Rugoglobigerina macrocephala (BrOnnimann) (35) Rugoglobigerina milamensis (Smith & Pessagno) (35) Rugoglobigerina pustulata (BrOnnimann) (35,45,54) Rugoglobigerina rotundata (BrOnnimann) (33) Rugoglobigerina rugosa (Plummer) (33,35,35,35,39,45,45) Trinitella scotti (BrOnnimann) (35) Globotruncana aegyptiaca (Nakkady) (33,35,39,45) Globotruncana andori (de Klasz) (33) Globotruncana area (Cushman) (22,33,33,35,35,35,39,45,45,54) Globotruncana asymetrica (Sigel) (35) Globotruncana bulloides (Vogler) (33,35,35,39,45,45) Globotruncana calciformis (Vogler) (33,35) Globotruncana contuse (Cushman) (22,35,45) Globotruncana coronata (White) (35) Globotruncana falsostuarti (Sigal) (33,35,45) Globotruncana fornicata (Plummer) (22,33,33,35,35,35,45,45,57) Globotruncana gagnebini (Tilev) (33,35,35) Globotruncana hilli (Pessagno) (22,33) Globotruncana lapparenti (Brotzen) (22,33,35,35,45) Globotruncana leupoldi (Boll!) (22,33,35) Globotruncana linneiana (d'Orbigny) (22,33,33,35,35,35,39,45) Globotruncana mariei (Banner & Blow) (35) Globotruncana obliqua (Herm) (35) Globotruncana plummerae (Gandolfi) (33,35) Globotruncana renzi (Thalman) (35) Globotruncana rosetta (Gandolfi) (33,35,35) Globotruncana stephensoni (Pessagno) (35) Globotruncana subcircuumodifer (Gandolfi) (33,35,35,45) Globotruncana scutilla (35) Globotruncana tricarinata (Quereau) (22,33,35,35,45) Globotruncana trinidadensis (Gandolfi) (35) Globotruncana ventricosa (White) (33,35,35,45,45) Globotruncanita elevata (Brotzen) (22) Globotruncanita gansserri (Bolli) (22,35) Globotruncanita stuarti (de Lapparent) (45) Globotruncanita stuartiformis (Dalbiez) (22,35,35,45) Rugotruncana circumnodifer (Finlay) (56,64,64,65) Rugotruncana subpennyi (Gandolfi) (33,35) Globotruncanella havanensis (Voorvijk) (33,35,35,35,39,45,54,64,64,65) 327

Lace Maastrichtian

Guembelitria cretacea (Cushman) (33,43,45,48,55,56,64,64,65) Heterohelix glabrans (Cushman) (12.32.39.43.45.45.48.48.56.61.64.64.65) Heterohelix globulosa (Ehrenberg) (32.33.35.39.41.42.43.45.55.56.61.64.64.65) Heterohelix navarroensis (Loeblich) (33,35,43) Heterohelix planata (Cushman) (12) Heterohelix pulchra (Brotzen) (12.32.35.35.39.41.42.43.45.45.48.56.61.64.65) Heterohelix punctulata (Cushman) (33,35) Heterohelix semicostata (Cushman) (35) Heterohelix striata (Ehrenberg) (12,32,33,33,35,35,39,41,43,45,45,48,48,55) Heterohelix ultimatumida (White) (32,33,39,48) Heterohelix planata (Cushman) (12,35,55) Gublerina cuvillieri (Kikoine) (12,32,33,35,39,45,45,48,48,55,64,65) Gublerina omatissima (41,43) Gublerina reniformis (Marie) (12,39,48,48) Gublerina robusta (de Klasz) (33,35,35,41,43) Pseudoguembelina costulata (Cushman) (12.32.33.33.35.35.35.39.42.43.48.48) Pseudoguembelina excolata (Cushman) (12,33,35,41,42) Pseudoguemblina kempensis (Esker) (12,35) Pseudoguembelina palpebra (BrOnnimann & Brown) (33,35) Pseudotextularia deformis (Kikoine) (12,33,33,35,35,39,43,45,48,48) Pseudotextularia elegans (Rzehak) (12.22.32.33.33.35.35.39.41.42.43.45.48.48) Pseudotextularia varians (Rzehak) (12,35,39,48) Raceguembellna fructicosa (Egger) (22,32,33,35,35,41,42,43,45) Raceguembelina intermedia (de Klasz) (35,43) Planoglobulina acervulinoides (Egger) (12,33,33,35,35,39,45,45,48) Planoglobulina brazoensis (Martin) (35,43) Planoglobulina carseyae (Plummer) (32,35,43) Planoglobulina glabrata (Cushman emend. Martin) (32,41,42) Planoglobulina multicamerata (de Klasz) (12,33,33,35,35,39,41,42,43) Planoglobulina riograndensis (Martin) (43) Globigerinelloides aspera (Ehrenburg) (41,42) Globigerinelloides nmltispinatus (Lalicker) (12,32,33,35,39,43,45,48,48,55,56, 61,64,64,65) Globigerinelloides prairiehillensis (Pessagno) (12.33.33.35.39.43.45.48.48) Globigerinelloides subcarinatus (BrOnnimann) (12.33.33.35.39.43.56.61.64.65) Globigerinelloides volutus (33,35) Globigerinelloides yacoensis (35) Schackoina multispinata (Cushman & Wickenden) (33) Hedbergella monmouthensis (Olsson) (32,45,55,56,64,64,65) Hedbergella sliteri n. sp, (55,56,64,64,65) Archaeoglobigerina australis n. sp, (56,64,64,65) ArchaeoglobIgerina blowi (Pessagno) (35) Archaeoglobigerina cretacea (d'Orbigny) (33) Rugoglobigerina hexacamerata (BrOnnimann) (12,33,35,35,43) Rugoglobigerina macrocephala (BrOnnimann) (22,32,33,33,35,43,55) Rugoglobigerina milamensis (Smith & Pessagno) (35,43) Rugoglobigerina pennyi (BrOnnimann) (32,43) Rugoglobigerina pustulate (BrOnnimann) (32,45,55) Rugoglobigerina rotundata (BrOnnimann) (33,35,42,55,57,61) Rugoglobigerina rugosa (Plummer) (12,22,32,33,35,35,39,41,42,43,45,45,48,55, 64) Bucherina sandidgei (BrOnnimann & Brown) (33,39) Trinitella scotti (BrOnnimann) (22,35,39) Globotruncana aegyptiaca (Nakkady) (12,22,33,33,35,35,39,43,45,48) Globotruncana andori (de Klasz) (33,35,39) Globotruncana area (Cushman) (12,22,32,33,33,35,35.41,42,43,45,45,48,48, 61,64,65 Globotruncana bulloides (Vogler) (33,35) Globotruncana calcifonnis (Vogler) (12,33,35,39,42) Globotruncana conica (White) (35) Globotruncana contusa (Cushman) (12,22,32.33,33,35,35,39,42,43,45,45,48,48,61) Globotruncana cf. coronata (41,42) Globotruncana duwi (43) Globotruncana falsostuarti (Sigal) (12,22,33,35,35,45 Globotruncana fornicata (Plummer) (12,33,41,42,57) Globotruncana fundiculosa (Subbotina) (42) Globotruncana gagnebini (Tilev) (32,33,35,35) Globotruncana hilli (Pessagno) (22,33) Globotruncana insignis (Chapman) (35) Globotruncana lamellosa (Sigel) (35) Globotruncana lapparenti (Brotzen) (22,35) Globotruncana leupoldi (Bolli) (22,33,35,35) Globotruncana linneiana (d'Orbigny) (12,22,32,33,33,35,35,39,45) Globotruncana navarroensis (Smith & Pessagno) (43) Globotruncana patelliformis (33,35,43) Globotruncana plunsnerae (Gandolfi) (33,35,43) Globotruncana rosetta (Gandolfi) (35) Globotruncana Stephensoni (Pessagno) (35,43) Globotruncana subcircumnodifer (Gandolfi) (33,35,42,64,65) Globotruncana tricarinata (Quereau) (22,33,33,35,42) Globotruncana trinidadensis (Gandolfi) (22,33,33,35,43) Globotruncana ventricosa (White) (12,33,35,39,45) Globotruncana sp. (12) Globotruncanita conica (White) (12,33,41,42,43) Globotruncanita elevata (Brotzen) (12,22,33,33,35,35,39,43,48,48) Globotruncanita ganserri (Bolli) (12,22,32,33,35,35,43) Globotruncanita stuarti (de Lapparent) (12,32,33,33,35,35,39,41,42,43,45) Globotruncanita stuartiformis (Dalbiez) (12,22,32,35,39,41,42,43,45,48) 329

Rugotruncana circwmodifer (Finlay) (55,56,64,64,65) Rugotruneana subpennyi (Gandolfi) (33,35,43,57) Abafrftoinpbalus interroedius (Bolli) (22,32,33,33,35,39,43,48,48,55,55,56,57, 61,64,65) Abathompbalus mayaroensis (Bolli) (12,32,33,33,35,35,39,42,43,45,45,48, 48,55,56,57,61,64,65) Globotruncanella bavanensis (Voorwijk) (12,22,33,33,35,35,39,42.45,48,56,57, 61,64,64) Globotruncanella petaloidea (Gandolfi) (22,43,32)