Last Glacial to Recent in the Gulf of California: A Sediment Trapping and Long Piston Coring Program

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Because of its geographic and oceanographic setting, the Gulf of California records a mix of oceanwide and regional oceanographic and climatic signals. The extremely high rates of sedimentation and frequent occurrence of annual laminae (varves) make the Gulf an ideal location for carrying out high resolution studies of paleoenvironmental change on the seasonal to millenial (and greater) scale. Despite the long interest in Gulf varves, this will be the first project to use sediment traps to directly determine the process of varve formation. The results will lead to a better understanding of how the climatic/oceanographic record is preserved, which will be used in the recover glacial as well as interglacial sediments. Following hypotheses will be tested: 1) that varve formation results from the seasonal input of wind-blown terrigenous material, 2) that the seasonal timing of light and dark laminae formation differs between the eastern and western sides of the Gulf, 3) that the deposition of nonlaminated sediment during glacial and Younger Dryas time resulted from increased oxygen and decreased nutrient content of intermediate depth waters in the Pacific Ocean, and 4) that deglacial oscillations of Gulf 18-0 resulted from episodes of lower salinity, perhaps caused by increased monsoonal circulation.