Global Change During the Paleocene – Eocene Thermal Maximum Appy
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Global change during the Paleocene – Eocene thermal maximum Appy Sluijs LPP Foundation 2006 Appy Sluijs Palaeoecology Institute of Environmental Biology Department of Biology Faculty of Science Utrecht University Laboratory of Palaeobotany and Palynology Budapestlaan 4 3584 CD Utrecht The Netherlands [email protected] ISBN 9039343020 NSG publication No. 2006 09 06 LPP Contributions Series No. 21 Cover design by Puck Sluijs and Fieke Sluijs. Photography and digital editing by Daan Verschuur and Martijn Houtkamp Global change during the Paleocene – Eocene thermal maximum Mondiale klimaatsveranderingen gedurende het Paleoceen-Eoceen temperatuur maximum (Met een samenvatting in het Nederlands) Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht, op gezag van de Rector Magnificus, Prof. Dr. W.H. Gispen, ingevolge het besluit van het College voor Promoties in het openbaar te verdedigen op woensdag 6 september 2006 des ochtends om 10.30 uur door Appy Sluijs Geboren op 16 maart 1980 te Woerden (Nederland) Promotor: Prof. Dr. André F. Lotter Palaeoecology, Institute of Environmental Biology, Utrecht University Laboratory of Palaeobotany and Palynology Co-Promotor: Dr. Henk Brinkhuis Palaeoecology, Institute of Environmental Biology, Utrecht University Laboratory of Palaeobotany and Palynology The research reported in this thesis was carried out at the Laboratory of Palaeobotany and Palynology, section Palaeoecology within the Institute of Environmental Biology, Utrecht University. The research was financially supported by the LPP Foundation and the TNO-Utrecht University Biogeology Center. Contents GENERAL INTRODUCTION AND SYNOPSIS 9 CHAPTER 1 Rapid acidification of the ocean at the Paleocene – Eocene 17 thermal maximum with James C. Zachos, Ursula Röhl, Stephen A.Schellenberg, David A. Hodell, Daniel C. Kelly, Ellen Thomas, Micah Nicolo, Isabella Raffi, Lucas J. Lourens, Heather McCarren and Dick Kroon Published in Science, 308: 1611-1615 (2005) CHAPTER 2 Astronomical pacing of late Paleocene to early Eocene 27 global warming events with Lucas J. Lourens, Dick Kroon, James C. Zachos, Ellen Thomas, Ursula Röhl, Julie Bowles and Isabella Raffi Published in Nature, 435: 1083-1087 (2005) CHAPTER 3 Subtropical Arctic Ocean temperatures during the 39 Paleocene-Eocene thermal maximum with Stefan Schouten, Mark Pagani, Martijn Woltering, Henk Brinkhuis, Jaap S. Sinninghe Damsté, Gerald R. Dickens, Matthew Huber, Gert-Jan Reichart, Ruediger Stein, Jens Matthiessen, Lucas J. Lourens, Nikolai Pedentchouk, Jan Backman, Kathryn Moran and the Expedition 302 Scientists Published in Nature, 441: 610-613 (2006). CHAPTER 4 Extreme warming of mid-latitude coastal ocean during 49 the Paleocene-Eocene Thermal Maximum: Inferences from TEX86 and Isotope Data with James C. Zachos, Stefan Schouten, Steven Bohaty, Thomas Quattlebaum, Henk Brinkhuis, Samantha Gibbs and Timothy J. Bralower Published in Geology (in press) 6 CHAPTER 5 The Paleocene-Eocene thermal maximum super 61 greenhouse: biotic and geochemical signatures, age models and mechanisms of climate change. with Gabriel J. Bowen, Henk Brinkhuis, Lucas Lourens and Ellen Thomas. Submitted for publication in: M. Williams, A. Haywood, J. Gregory and D. Schmdt (Editors), Deep time perspectives on Climate Change. Geological Society of London, London, UK. CHAPTER 6 Eustatic sea level rise during the Paleocene – Eocene 89 thermal maximum with Henk Brinkhuis, Erica M. Crouch, Steven Bohaty, Cédric M. John, Gert-Jan Reichart, Stefan Schouten, James C. Zachos, Gerald R. Dickens, Jaap S. Sinninghe Damsté and André F. Lotter CHAPTER 7 Global warming precedes the carbon isotope excursion 107 at the Paleocene – Eocene thermal maximum With Henk Brinkhuis, Stefan Schouten, Robin Deltrap, Cédric M. John, Steve Bohaty, Gert-Jan Reichart, Lucas J. Lourens, Jaap S. Sinninghe Damsté, Erica Crouch and James C. Zachos APPENDIX 1 From greenhouse to icehouse: organic-walled 117 dinoflagellate cysts as paleoenvironmental indicators in the Paleogene With Jörg Pross and Henk Brinkhuis. Published in Earth-Science Reviews 68: 281-315 (2006) APPENDIX 2-5 Supporting information to Chapters 1, 2, 3 and 7 155 REFERENCES 191 ALGEMENE INLEIDING EN SAMENVATTING 213 ACKNOWLEDGEMENTS 221 CURRICULUM VITAE 225 7 8 General introduction and synopsis 9 Introduction Atmospheric CO2 concentrations expected for the next centuries have not been equaled since the early Paleogene, approximately 66 to 45 Million years (Ma) ago. The early Paleogene global climate appears to have been substantially warmer than that of present day, likely in response to high greenhouse gas concentrations. For example, large ice sheets were absent during most of this period. Understanding of the impact of such ‘greenhouse’ conditions on early Paleogene global climate is vital to identify and quantify present and future climate feedbacks related to rising atmospheric carbon concentrations. The research I have carried out focused on a wide range of early Paleogene time intervals, including the late Paleocene, early Eocene and Middle Eocene, late Eocene, and earliest Oligocene (see CV on p. 226). In this thesis, I shall specifically focus on global change that occurred during a brief period of extreme global warming called the Paleocene- Eocene thermal maximum (PETM), approximately 55.5 Ma ago. Close to the Selandian - Thanetian boundary (~59 Ma), a long-term global warming trend initiated, which culminated in the Early Eocene Climatic Optimum (EECO; 52-50 Ma). During the middle and late Eocene long term cooling occurred, eventually resulting in significant expansion of Antarctic ice sheets during the earliest Oligocene. Although greenhouse gas concentrations are likely to have played an important role, the mechanisms behind these long-term trends are still poorly understood. The PETM, which characterizes the Paleocene-Eocene boundary, is almost certainly associated with increased greenhouse gas concentrations. The warming is evidenced by large oxygen isotope (δ18O) excursions in marine and terrestrial carbonates and increased Mg/Ca ratios in foraminifera. Furthermore, poleward migration of (sub)tropical marine and terrestrial biota characterizes the PETM. Associated with this warming is a negative 2.5-6 ‰ stable carbon isotope (δ13C) excursion (CIE), evidencing the fast injection 12 of C-enriched carbon in the form of CO2 or CH4 into the global exogenic carbon pool. The apparent conjunction between the carbon input and warming has fuelled the hypothesis that the increased atmospheric CO2 and/or CH4 concentrations caused an enhanced greenhouse effect at the PETM, superimposed on the already high greenhouse gas concentrations of the earliest Paleogene. The duration of the negative δ13C excursion and the subsequent recovery is in the order of 170 kyr. Although many studies have focussed on the PETM, basic questions on the nature of this event have remained unanswered. First of all, why did the PETM occur when it did and is it unique in Earth’s history? Second, to which degree is the input of light carbon that caused the CIE causally related to global change? In deep marine sections, the CIE and the δ18O excursion occur at the same level, but these sections are relatively condensed and are not suitable for detecting (sub)millennial-scale leads and lags. Many PETM sections from the deep sea show strong dissolution of carbonate related to a shoaling of the lysocline, but 10 Introduction the effect of elevated carbon concentrations on ocean carbon chemistry has not been quantified. Moreover, although reasonable estimates for low latitude warming exist, the question remains what the magnitude of warming on a global scale has been? And what effect did this warming have on sea level?, This thesis addresses all of the above questions by detailed multi-proxy analyses of a variety of sites from the deep sea to the shelf and from extreme high to low latitudes. Among the most important proxies that have been used to detect paleoenvironmental changes reported in this thesis are the organic-walled cysts of dinoflagellates (dinocysts). Dinoflagellates are protists. The different species have a wide range of ecological preference: for instance some are heterotrophic, some are autotrophic, and some are more competitive in warm waters, whereas others thrive better in cold waters. Over the past decades, the ecology of extant species and the paleoecology of extinct taxa (although we only know their cysts) have been mapped increasingly well. Dinocyst assemblages in sediments can, hence, be used to reconstruct the ecology of the waters in which the dinoflagellates lived. By presenting case-studies from around the globe, Appendix 1 provides a concise state-of-the-art review of our present understanding of the paleoenvironmental significance of dinocysts in the Paleogene (~ 65-25 Ma). Representing long-term as well as transient warming and cooling, this episode holds the key to the understanding of dinocyst paleoecology as well as their potential in reconstructing paleoenvironments. We discuss how dinocysts can be used for the reconstruction of Paleogene sea-surface productivity, temperature, salinity, stratification, and paleo-oxygenation along with their applications in sequence stratigraphy, oceanic circulation, and general water mass reconstructions. Many data in this thesis are generated on sediment cores that were drilled in the framework of Ocean Drilling Program (ODP) Leg 208 on the Walvis Ridge in the subtropical Southeast Atlantic (2003) and Integrated