THE USE OF OSTRACODA IN THE PALAEOENVIRONMENTAL RECONSTRUCTION OF THE GULF OF CARPENTARIA, AUSTRALIA, FROM THE LAST INTERGLACIAL TO PRESENT A thesis submitted in fulfilment of the requirements for the award of the degree DOCTOR OF PHILOSOPHY from the UNIVERSITY OF WOLLONGONG by JESSICA MARIE REEVES, BSc (Hons). SCHOOL OF EARTH AND ENVIRONMENTAL SCIENCES 2004 CERTIFICATION I, Jessica M. Reeves, declare that this thesis, submitted in fulfilment of the requirements for the award of Doctor of Philosophy, in the School of Earth and Environmental Sciences, University of Wollongong, is wholly my own work unless otherwise referenced or acknowledged. The document has not been submitted for qualifications at any other academic institution. Jessica M. Reeves 03 May 2004 Table of Contents List of figures…………………………………………………………………………………….v List of tables…………………………………………………………………………………….vii Abstract………………………………………………………………………………………….vii Acknowledgements………………………………………………………………………………ix INTRODUCTION………………………………………………………………………………1 Thesis outline……………………………………………………………………………………. 3 1. THE GULF OF CARPENTARIA………………………………………………………… 7 1.1 Location of the study area………………………………………………………………….7 1.2 Geological history of the Gulf of Carpentaria……………………………………………...8 1.3 Physiography of the modern basin………………………………………………………...13 1.4 Modern sedimentation in the gulf………………………………………………………….20 1.5 Meteorological context…………………………………………………………………….23 1.6 The modern environment………………………………………………………………….26 1.7 Summary…………………………………………………………………………………..28 2. THE STAT OF KNOWLEDGE…………………………………………………………….29 2.1 Pleistocene sea-level history………………………………………………………………29 2.2 The importance of the Gulf of Carpentaria………………………………………………..31 2.3 Previous studies of the gulf region………………………………………………………...32 2.3.1 Environments of the Gulf of Carpentaria – past and present………………………..32 2.3.2 Sea-level reconstructions of the gulf region…………………………………………37 2.3.3 Palaeoclimatic framework…………………………………………………………...38 2.4 Present coring and research program………………………………………………………42 2.5 Direction and purpose of this study………………………………………………………..43 3. MATERIALS AND METHODS……………………………………………………………..47 3.1 Background to the Gulf of Carpentaria project……………………………………………..47 3.2 Coring methodology and preliminary investigations……………………………………….48 3.3 Sampling method employed………………………………………………………………...49 3.4 Sediment particle-size analysis technique…………………………………………………..50 3.5 Micropalaeontological sample preparation………………………………………………….51 3.6 Microscopic analysis of sediment samples………………………………………………….52 3.7 XRD analysis of sediment samples…………………………………………………………52 3.8 Ostracod analysis methodology……………………………………………………………..52 3.9 SEM analysis methods………………………………………………………………………55 3.10 Stable-isotope analysis of ostracod valves…………………………………………………55 3.11 Dating methods…………………………………………………………………………….56 3.11.1 Radiocarbon dating…………………………………………………………………..56 3.11.2 Amino acid racemisation dating……………………………………………………..57 3.11.3 Luminescence dating………………………………………………………………...58 4. SEDIMENT ANALYSES……………………………………………………………………...59 4.1 Sedimentary parameters investigated from the core material……………………………….59 4.1.1 Particle-size……………………………………………………………………………..59 4.1.2 Colour…………………………………………………………………………………..59 4.1.3 Water content……………………………………………………………………………59 4.1.4 Mineralogy………………………………………………………………………………60 4.1.5 Microfauna………………………………………………………………………………62 4.2 Depositional facies defined from the gulf cores……………………………………………...63 4.4 Sampled sites…………………………………………………………………………………64 4.5 Sediment description of core MD-32…………………………………………………………69 4.6 Results of preliminary observation of the physical parameters………………………………71 4.6.1 Particle-size analysis……………………………………………………………………..71 4.6.2 Water content…………………………………………………………………………….73 4.7 Microscopic observation of the sediment of core MD-32……………………………………74 4.8 Discussion and interpretation of the sediment of core MD-32……………………………….80 4.9 Comparison with other cores…………………………………………………………………98 4.9.1 Sediments of core MD-33………………………………………………………………..101 4.9.2 Sediments of core MD-31………………………………………………………………..109 4.9.3 Sediments of core MD-30………………………………………………………………..117 4.9.4 Sediments of core MD-29………………………………………………………………..123 4.9.5 Sediments of core MD-28………………………………………………………………..129 4.10 Palaeoenvironments of the gulf, as observed through the core sediment…………………..135 5. OSTRACOD ANALYSES…………………………………………………………………..146 5.1 Introduction to ostracods………………………………………………………………….146 5.1.1 Overview of ostracods………………………………………………………………...146 5.1.2 Ontogeny………………………………………………………………………………147 5.1.3 Valve structure and taxonomy………………………………………………………...150 5.2 Ostracods as palaeoenvironmental indicators……………………………………………...152 5.2.1 Ecology………………………………………………………………………………...152 5.2.2 Marine environment……………………………………………………………………155 5.2.3 Marginal marine environment………………………………………………………….157 5.2.4 Non-marine environment……………………………………………………………….159 5.2.5 Environmentally cued polymorphism…………………………………………………..164 5.2.6 Depositional environment………………………………………………………………167 5.3 Modern ostracod fauna………………………………………………………………………172 5.3.1 Ostracods from surface samples of the Gulf of Carpentaria……………………………172 5.3.2 Previous regional studies………………………………………………………………..179 5.4 Results of the ostracod analysis of core MD-32……………………………………………...198 5.4.1 Ostracod fauna present in core samples………………………………………………..198 5.4.2 Ostracod assemblages from core MD-32……………………………………………….205 5.5 Cluster analysis………………………………………………………………………………223 5.5.1 R-mode cluster analysis………………………………………………………………….224 5.5.2 Q-mode cluster analysis………………………………………………………………….226 5.6 Discussion and interpretation of the ostracod observations………………………………….235 6. STABLE-ISOTOPE ANALYSES…………………………………………………………….252 6.1 Introduction to stable-isotopes………………………………………………………………252 6.2 Oxygen stable-isotope composition…………………………………………………………253 6.2.1 Relationship between δ180 of water and δ180 of inorganically precipitated carbonates……………………………………………………………………….253 6.2.2 δ180 of meteoric water…………………………………………………………………..255 6.2.3 δ180 of seawater…………………………………………………………………………256 6.2.4 δ180 of marginal marine water…………………………………………………………..257 6.2.5 δ180 of lake water……………………………………………………………………….257 6.3 Stable carbon isotope composition…………………………………………………………..260 6.3.1 Relationship between δ13C of water and δ13C of precipitated carbonates………………260 6.3.2 δ13C of plants…………………………………………………………………………….262 6.3.3 δ13C of seawater…………………………………………………………………………263 6.3.4 δ13C of marginal marine water…………………………………………………………..264 6.3.5 δ13C of non-marine water………………………………………………………………..264 6.4 Ostracods and stable-isotope analysis……………………………………………………….264 6.5 Vital effects………………………………………………………………………………….266 6.6 δ18O and δ13C of ostracod valves as palaeoenvironmental indicators………………………268 6.6.1 Marine environment…………………………………………………………………….268 6.6.2 Marginal marine environment………………………………………………………….269 6.6.3 Non-marine environment……………………………………………………………….270 6.7 Covariance of δ18O and δ13C………………………………………………………………...272 6.8 δ18O of the modern Gulf of Carpentaria……………………………………………………..277 6.9 Stable-isotope analyses from core MD-32…………………………………………………..283 6.10 Results………………………………………………………………………………………284 6.11 Discussion and interpretation……………………………………………………………….301 6.12 Other palaeoenvironmental indicators………………………………………………………317 6.12.1 Pollen analyses…………………………………………………………………………317 6.12.2 Other geochemical analyses……………………………………………………………323 7. SYNTHESIS…………………………………………………………………………………..335 7.1 Sea level……………………………………………………………………………………335 7.2 Climate and Hydrology…………………………………………………………………….353 7.3 Conclusion………………………………………………………………………………… 364 REFERENCES…………………………………………………………………………………..366 APPENDICES……………………………………………………………………………………395 Appendix 1a. Core log of core MD-28…………………………………………………………397 Appendix 1b. Core log of core MD-29………………………………………………………….399 Appendix 1c. Core log of core MD-30………………………………………………………….401 Appendix 1d. Core log of core MD-31………………………………………………………….403 Appendix 1e. Core log of core MD-33………………………………………………………….405 Appendix 2a. Sedimentary parameters of core MD-31…………………………………………407 Appendix 2b. Sedimentary parameters of core MD-32…………………………………………415 Appendix 2c. Sedimentary parameters of core MD-33…………………………………………423 Appendix 3a. Quartz grains of unit 7, MD-32…………………………………………………..427 Appendix 3b. Quartz grains of unit 4, MD-32…………………………………………………..427 Appendix 4a. Results of EDX analyses of material from core MD-32…………………………429 Appendix 4b. Results of XRD analyses of material of cores MD-28, 29, 30, 32………………429 Appendix 5a. 14C AMS dates from the Gulf of Carpentaria cores………………………………431 Appendix 5b. Marine reservoir correction for NE Australia……………………………………433 Appendix 6. Taxonomic list of ostracods described from core MD-32………………………...435 Appendix 7. Ostracod plates…………………………………………………………………….450 Appendix 8. Ostracod genus distribution……………………………………………………….470 Appendix 9. Stabel isotope results from core MD-32………………………………………….473 List of figures Chapter 1 1.1 Locality map of the Gulf of Carpentaria region. 5 1.2a Location of basins within the Gulf of Carpentaria region. 9 1.2b Outline of the basin stratigraphy and lithology of the Gulf of Carpentaria. 9 1.3 Interpretive line drawing of seismic line 17 across the Gulf of Carpentaria. 11 1.4 Geomorphic units of the Gulf of Carpentaria, Australia. 15 1.5 Geomorphic units of the southern lowlands of New Guinea. 15 1.6 Major surficial sedimentary zones of the Gulf of Carpentaria. 19 1.7 Map showing the location