HR: 0800h
AN: PP11A-0218    [Abstracts]
TI: Tropical sea Surface Temperature and Salinity Variability During Deglaciation Inferred From A new Tahitian Coral Oxygen Isotope and Sr/Ca Record
AU: * Coppola, A I
EM: acoppola@email.arizona.edu
AF: Department of Geosciences, University of Arizona 1040 East 4th Street, Tucson, AZ 85721, United States
AU: Cole, J
EM: jecole@email.arizona.edu
AF: Department of Geosciences, University of Arizona 1040 East 4th Street, Tucson, AZ 85721, United States
AU: Barnett, H
EM: hbarnett@email.arizona.edu
AF: Department of Geosciences, University of Arizona 1040 East 4th Street, Tucson, AZ 85721, United States
AU: Tudhope, A W
EM: sandy.tudhope@ed.ac.uk
AF: School of Geosciences, University of Edinburgh Kings Building West mains Road, Edinburgh, EH9 3JW, United Kingdom
AU: Ault, T R
EM: tault@email.arizona.edu
AF: Department of Geosciences, University of Arizona 1040 East 4th Street, Tucson, AZ 85721, United States
AB: We investigate tropical sea surface temperature (SST) variability during the last deglaciation from a subfossil Porites coral. Since this species is still growing in the same location today, this analysis allows for a direct comparison between modern and prehistoric behavior as deglaciation proceeded. The coral sample was recovered during IODP Leg 310 drilling of offshore fossil reefs (sample 310 11A 6R 1W 27,0-40,0). Stratigraphic evidence and mean δ¹⁸O values suggest that the coral grew as sea level began to rise just following the last glacial maximum; these inferences will be confirmed with U-series dating now in progress. Exploration for diagenetic features using SEM and thin sections has allowed us to identify the parts of the coral slab most suitable for paleoclimate analysis. To reconstruct sea surface conditions during this time, we measured δ¹⁸O and Sr/Ca at 0.5mm resolution; annual density banding indicates that our record spans roughly 15 years with an annual growth rate of 9-15 mm/yr. Mean oxygen isotope values fall about 2‰ heavier than a modern coral from neighboring Moorea. Assuming an ice volume correction of 0.8-1.0‰, our δ¹⁸O results suggest that cooler SSTs were probably accompanied by regional seawater δ¹⁸O increases, as a paleotemperature interpretation of the isotopic results yields values around 5- 6^oC, larger than expected. Modern Sr/Ca calibration data are planned to allow us to use Sr/Ca to partition the temperature and seawater isotope components of this signal, and replication of both Sr/Ca and δ¹⁸O will allow us to assess additional uncertainties. The annual cycle of coral δ¹⁸O is comparable or slightly reduced from the modern, although differences in site exposure may partly account for the difference we observe. We will compare our temperature inferences with additional data and with coupled model results.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 4215 Climate and interannual variability (1616, 1635, 3305, 3309, 4513)
DE: 4220 Coral reef systems (4916)
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting