As a primary feature of ocean circulation and key component of the global carbon cycle, changes in the thermocline must be accounted for if we are to understand the processes involved in Quaternary climatic fluctuation. Preliminary results, based on the benthic foraminiferal 018 and 13c records in cores from the mid-and lower-thermocline at Little Bahama Bank, suggest the glacial thermocline at about 540 meters wataer depth was approximately 2oC cooler and more 13c enriched that it is today. The objective for this project is to determine how bathymetric profiles of nutrients and physical properties within the thermocline have evolved from the last glacial maximum to the present. The goal is to relate thermocline evolution in the North Atlantic subtropical gyre to glacial- interglacial changes of physical forcing factors, the global carbon budget/atmospheric pCO2 and intermediate/deep water circulation. In order to accomplish this goal, a suite of cores from the well-sedimented southern flank of Little Bahama Bank will be collected Over the depth range 400 to 1700 meters. %%% A primary feature of ocean circulation is the depth of the thermocline where warm, well-mixed surface water lies on top of colder deep water. the depth to this fundamental boundary must be known for glacial periods in order to reconstruct the history of oceans during the last glacial maximum. This project will use oxygen and carbon iosotopes in benthic foraminifera found in sedimentary cores from the flanks of Little Bahama Bank to document the fluctuations of the thermocline during fluctuations of the climate. The evolution of patterns in theromcline thickness, temperature, and nutrient supply will be determined for the first time in an open ocean environment where local coastal effects will be absent.
