HR: 1340h
AN: PP13A-0600    [Abstracts]
TI: MILLENNIAL-SCALE CLIMATE VARIABILITY IN THE SUBTROPICAL ATLANTIC DURING THE MIDDLE PLEISTOCENE
AU: * Gibbons, F
EM: ferng@uchicago.edu
AF: University of Chicago, Dept of the Geophysical Sciences, chicago, IL 60637
AU: Fisler, J
EM: jaf328@psu.edu
AF: Penn State, Dept of Geosciences, University Park, PA 16802
AU: Martin, P
EM: pmartin@uchicago.edu
AF: University of Chicago, Dept of the Geophysical Sciences, chicago, IL 60637
AU: Billups, K
EM: kbillups@udel.edu
AF: University of Delaware, College of Marine Studies, Lewes, DE 19958
AB: We are generating Globigerinoides ruber (white, ss) oxygen isotope and Mg/Ca records from ODP Site 1058 to assess relative climate stability in subtropical northwestern Atlantic during the mid Pleistocene, Marine Isotope Stages (MIS) 11-22. Currently, our records span MIS 11 (a portion only) through MIS 15 with a temporal resolution of about 800-1000 years. The paired Mg/Ca and d18O records allow us to reconstruct fluctuations of sea surface temperatures (SST) and the regional oxygen isotopic composition of surface water on millennial time scales during one of the most extreme glacial-interglacial transitions of the Pleistocene. Our ultimate goal is to test the hypothesis that relative climate stability is linked to the extent of continental glaciation (ice volume). The d18O record displays rapid, high amplitude variability during glacial MIS 12 and the MIS 12 to MIS 11 deglaciation. The Mg/Ca results show that the long-term trends in the temperature record follow the general glacial-interglacial pattern implying SST changes concurrent with large-scale climate change. Portions of the Mg/Ca record generated at higher resolution reveal SST variability similar in timing to variability observed in the d18O record, particularly during MIS 13 and the MIS 13/12 transition. The total amplitude of SST changes implied by the Mg/Ca data is ~6øC, with absolute temperatures ranging from about 24 to 30øC. The current records show that this site is sensitive to millennial-scale variability during the extreme glacial MIS 12 and the MIS 12/11 deglaciation, but not in the older portion of the oxygen is record (MIS 14) thus far generated. Ultimately, the entire record will show if other glacial extremes such as MIS 16 contains similarly high variability, which would further support the hypothesis that ice sheet size plays an important role in determining the amplitude of millennial-scale climate change.
DE: 4870 Stable isotopes
DE: 4875 Trace elements
DE: 4267 Paleoceanography
DE: 1635 Oceans (4203)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting