HR: 16:50h
AN: PP54B-04    [Abstracts]
TI: From Greenhouse to Icehouse: Evidence for Late Early Eocene Concomitant Cooling of Southern Ocean Surface Waters and Global Deep Waters From Dinoflagellate Endemism
AU: * Brinkhuis, H
EM: H.Brinkhuis@bio.uu.nl
AF: Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, Utrecht, 3584 CD Netherlands
AU: Huber, M
EM: huberm@purdue.edu
AF: Earth & Atmospheric Science, Purdue University, 1397 Civil Engineering Bldg., Purdue University, West Lafayette, IN IN 47907 United States
AU: Sluijs, A
EM: A.Sluijs@bio.uu.nl
AF: Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, Utrecht, 3584 CD Netherlands
AU: Warnaar, J
EM: J.Warnaar@bio.uu.nl
AF: Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, Utrecht, 3584 CD Netherlands
AU: Bujak, J P
EM: jonathan@bujakmudge.com
AF: Bujak Research International, 105 North Park Drive, Blackpool, FY3 8NE United Kingdom
AU: Zachos, J C
EM: jzachos@es.ucsc.edu
AF: Department of Earth Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AB: ODP Leg 189 drilling around Tasmania retrieved continuous Eocene records from the Southern Ocean - Antarctic Margin. The shallow marine, pro-deltaic successions of Sites 1170, 1171 and 1172 include the interval representing the onset (55 Ma) and termination (50 Ma) of the Early Eocene Climatic Optimum (EECO). The end of the EECO is globally reflected in the oceans by the onset of increasingly cooler deep-water temperatures, and marks the onset of the trend towards the Icehouse world. Here we show that a strong increase of endemic Antarctic dinoflagellates precisely matches the termination of the EECO in the Southern (Pacific) Ocean. The record of these surface-dwelling organisms thus indicates that changes of surface water parameters, notably temperature, occurred near simultaneously with global deep-water temperature changes. Moreover, the signal coincides with the return to heavier d13C-values, and atmospheric CO2 decline. Comparison of the field data with predictions from fully coupled climate model simulations, and a new basic understanding of Eocene Southern Ocean circulation, suggests that changes in carbon burial was driving changes in atmospheric greenhouse gasses, and the apparently coupled surface- and deep-water temperature signals.
DE: 4805 Biogeochemical cycles (1615)
DE: 4870 Stable isotopes
DE: 3030 Micropaleontology
DE: 1635 Oceans (4203)
DE: 0325 Evolution of the atmosphere
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting