HR: 1340h
AN: PP43A-0669    [Abstracts]
TI: Holocene sea surface temperature reconstructions from the Arabian Sea
AU: * Dahl, K A
EM: kdahl@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Geology and Geophysics WHOI MS #22, Woods Hole, MA 02543 United States
AU: Oppo, D W
EM: doppo@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Geology and Geophysics WHOI MS #22, Woods Hole, MA 02543 United States
AB: Sea surface temperature (SST) and the oxygen isotopic composition of seawater (δ¹⁸O_w) were reconstructed at ODP Site 723B on the Oman Margin for the time period from the Last Glacial Maximum (LGM, ~20,000 years ago) to the present and at Site 39KG/56KA on the Pakistan Margin from 5,000 years ago (5~ka) to the present. This was accomplished using paired Mg/Ca and δ¹⁸O analyses on two species of planktonic foraminifera, Globigernoides ruber and Globigerina bulloides. At Site 723B we find low SSTs during the Early Holocene, implying stronger than present summer monsoon upwelling, and a gradual increase in SSTs after 6~ka, implying a weakening of summer monsoon upwelling during this time. Comparison of our Mg/Ca SST results with other published SST records from this site reveals a consistent LGM to Holocene warming of 2-3°C; however, the Holocene temperature trends suggested by the different records vary greatly. These differences are likely a function of differences in the seasonality of proxy production. In contrast to the Oman Margin records, our Mg/Ca record from the Pakistan Margin agrees well with a previously published alkenone record from the same site, with both proxies suggesting a long term increase in SST (and therefore a decrease in winter monsoon strength) from 5~ka to the present. As SST at these sites can be an indicator of the strength of the Indian Monsoon, it is critical that we consider and understand the inherent seasonality of our SST proxies.
DE: 1620 Climate dynamics (0429, 3309)
DE: 1637 Regional climate change
DE: 4954 Sea surface temperature
DE: 4964 Upwelling (4279)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005