Collaborative Research: Evolution of the Deep South Atlantic Since the Last Interglacial Period Inferred from a Depth Transect of Cape Basin Sediment Cores

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There is considerable evidence that the deep ocean plays some role in governing the evolution of Pleistocene ice ages and interglacial periods. Yet after several decades of research, there is still debate over the degree to which sedimentary tracers can distinguish differences in deep ocean circulation between ice age oceans and the modern ocean. This collaborative project will investigate past ocean circulation changes by generating multi-proxy records for several common paleoceanographic tracers (including benthic d18O and d13C, radiocarbon, Cd/Ca, Zn/Ca and B/Ca) for eight time slices over the last glacial-interglacial cycle using cores along a depth transect from the Namibian margin and Cape Basin. These time slices would represent the step in evolution from interglacial state through a full glacial cycle. The research will focus around a series of questions concerning water mass evolution in the Atlantic Ocean, the connection between circulation and carbon cycling, differences between conservative and non-conservative proxies, and the possibility for major boundary condition changes distinct from ocean mixing effects. Broader impacts:This project will provide a detailed picture of the mixing between the two principal deep water masses of the world's ocean across a full ice cycle, which will be of widespread use to oceanographers and climate scientists. Funding will support two Ph.D. students and provide significant experience in proxy data collection and interpretation. The project will also serve as a platform for a summer REU fellow and provide support for several undergraduate students to learn research and laboratory techniques. Additionally, funding will help develop a lesson on deep earth circulation through the Deep Earth Academy at Texas A&M University.