HR: 16:30h
AN: PP24A-03    [Abstracts]
TI: Evaluating Whether Tropical Ocean/Atmospheric Changes Influenced the Timing of Deglaciation
AU: * Stott, L D
EM: stott@usc.edu
AF: University of Southern California, Department of Earth Sciences 3651 Trousdale Pkwy, Los Angeles, CA 90089 United States
AU: Thunell, R
EM: Thunell@geol.sc.edu
AF: University of South Carolina, Department of Geological Sciences University of South Carolina , Columbia, sc 29208 United States
AB: At the onset of the last glacial termination SSTs in the western tropical Pacific began to warm at 18ka but surface water δ¹⁸O_SMOW values, a proxy for both local salinity and global ice volume did not decrease until 14.6ka. In contrast, benthic δ¹⁸O values from the same sites (at water depths between 1800 and 2100m) decreased by 0.6‰ between 18 and 14.6ka. Benthic Mg/Ca paleothermometry indicate there was no substantial change in the temperature of intermediate waters prior to 14.6ka. The benthic δ¹⁸O decrease that began at 18ka therefore indicates there was a freshening of Pacific intermediate waters on the order of 0.5-1‰ or ¹⁶O-enriched water was added to the oceans from melting ice sheets well before 14.6ka. Recent studies have documented sea level rise starting as early as 19ka but evidence from deep sea benthic isotopic evidence has been lacking. We examine the possible implications of the tropical deep sea and surface water δ¹⁸O records in the context of fingerprinting potential mechanisms that were responsible for the sequence of events during the last glacial termination. One potential implication is that the warming of the tropical oceans that began around 18ka could help explain why the Antarctic began to warm earlier than the northern high latitudes when solar insolation was decreasing over the southern hemisphere and atmospheric CO₂ and CH₄ had not yet begun to increase substantially. The changes in tropical ocean/atmospheric conditions during deglaciation may therefore represent a key to understanding the phasing of climate changes between the high and low latitudes.
DE: 3030 Micropaleontology (0459, 4944)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4870 Stable isotopes (0454, 1041)
DE: 9604 Cenozoic
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005