Late Quaternary carbonate accumulation along eastern South Atlantic Ocean

Water masses originating from both the North Atlantic Ocean and the Southern Ocean intersect the Walvis Ridge and Namibian margin of southwest Africa. Changes in the distribution and properties of these water masses through time are reflected by variations in the nature of the sediments accumulating along this margin. As part of our ongoing studies, we are investigating the interrelationships between oceanographic/climatic change and the accumulation of carbonate minerals during the late Quaternary. A suite of cores that possess sediment records corresponding to the most recent glacial-interglacial cycles was collected from the water depth range of 500 to 3000 meters. Cores that preserve records of key water masses were selected for detailed analyses. Sediment bulk density, the concentration of calcium carbonate, and the relative proportions of carbonate minerals were precisely determined at regular depth intervals in these cores. Foraminiferal d18O and C-14 dates provide chronologic control. Results will be used to calculate how the accumulation rates of carbonate minerals on the seafloor vary through time, and the correspondence of such variation to changes in ocean circulation and climate will be assessed.