SEA SURFACE TEMPERATURE ESTIMATES FROM THE PLIOCENE BENGUELA CURRENT UPWELLING SYSTEM

Planktic foraminifer assemblages have been analyzed for ODP Site 1085, located in the Cape Basin off of the west coast of South Africa. This site is located in the South Atlantic Benguela Current system in a zone of upwelling and high primary productivity. Today the Benguela Current upwelling system supplies the coastal area of southwest Africa with cold, nutrient-rich water. Sea surface temperature (SST) records based on alkenone unsaturation indices indicate that surface waters in this upwelling zone were much warmer during the Pliocene. We have sampled mid-Piacenzian (3.264 to 3.025 Ma) sediments from ODP Site 1085 (26.37°S, 13.99°E, 1713m water depth) at an interval of ~4000 years for micropaleontological analyses. SST estimates based on planktic foraminifer assemblages will complement existing temperature estimates to better characterize this Pliocene upwelling system. This work will contribute to a larger project examining changes in the source waters at all the major upwelling systems of the Pliocene ocean. This research is part of the PRISM (Pliocene Research, Interpretation and Synoptic Mapping) Project at the U.S. Geological Survey.