HR: 0800h
AN: PP31D-0650    [Abstracts]
TI: Laurentide Ice Sheet Meltwater and Sea Surface Temperature in the Gulf of Mexico During the Late Pleistocene
AU: * Whitaker, J L
EM: jwhitaker@marine.usf.edu
AF: College of Marine Science University of South Florida, 140 7th Avenue S., St. Petersburg, FL 33701, United States
AU: Flower, B P
EM: bflower@marine.usf.edu
AF: College of Marine Science University of South Florida, 140 7th Avenue S., St. Petersburg, FL 33701, United States
AU: Guilderson, T P
EM: tguilderson@llnl.gov
AF: Center for Accelerator Mass Spectrometry Lawrence Livermore National Laboratory, P.O. Box 808, L-397, Livermore, CA 94550, United States
AU: Hastings, D W
EM: hastindw@eckerd.edu
AF: Collegium of Natural Sciences Eckerd College, 4200 54th Avenue South, St. Petersburg, FL 33711, United States
AB: During Late Pleistocene glacial terminations Laurentide Ice Sheet (LIS) meltwater enters the Gulf of Mexico (GOM). As of yet, it is unclear whether or not weak warm periods, such as marine isotope stages (MIS) 3, 5a and 5c, were associated with meltwater discharge events. It is equally unknown how the timing of these events, if they existed, relates to millennial scale warm intervals determined from Greenland and Antarctic ice core records. To understand the dynamics of LIS melting we investigate the phasing between meltwater events and sea surface temperature (SST) changes. ODP site 625, drilled at a water depth of ~900 m near De Soto Canyon, provide continuous records of MIS 2-6 sampled at a mean temporal resolution of ~400 years. Results from paired Mg/Ca-SST and δ¹⁸O on Globigerinoides ruber (white and pink variety) provide evidence for orbital-to millennial influence on salinity and temperature in the GOM. Across the MIS 6/5 termination SST increases ~1000 years before changes in δ¹⁸O _seawater, a result similar to the most recent deglaciation. Considering that Holocene G. ruber (pink) δ¹⁸O values are -1.5‰, MIS 3 and 5 exhibit negative excursions of 0.5‰ or more with values reaching -2.8‰. The greater than 1‰ excursions, which cannot be attributed solely to temperature, suggest significant salinity changes. The timing of southern routing of LIS meltwater has implications for potential disruption of meridional overturning circulation (MOC) during late Pleistocene orbital- to millennial-scale climate changes. However, the initial forcing to instigate large meltwater perturbations is ambiguous. Determining the phasing of regional SST and LIS meltwater events in relationship to high latitude records will increase understanding of important climate feedbacks and the role of the tropics in climate change.
DE: 4870 Stable isotopes (0454, 1041)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4934 Insolation forcing
DE: 4940 Isotopic stage
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting