International Research Fellowship Program: Sediment Transport in Marine Environments: Processes, Timescales, and Paleoclimatic Implications

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0853110LeeThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Victoria E. Lee to work with Dr. Gideon M. Henderson at Oxford University in the United Kingdom.The aim of this project is to determine the timescales and processes involved in the formation and evolution of marine sediment deposits. This information is necessary for accurate interpretation of the paleoclimatic and paleoceanographic proxy records hosted in marine sediments. Of particular interest are proxy records in deep-sea drift deposits. Lateral advection of fine-grained sediment to drifts causes high sedimentation rates that are desirable for high-resolution paleoclimate studies. However, this process can also cause spatial and temporal decoupling of proxies associated with different grain sizes ? lateral advection of fine-grained sediment by deep ocean currents can transport older proxies recording non-local environmental conditions to a given depositional site. Therefore, deciphering a given location?s paleoproxy record requires information about the transport history of the fine-grained sediment fraction. The PI is investigating the effects of glacial-interglacial sea level changes on the transport history of the Bermuda Rise sediments, which comprise a deep-sea drift site of paleoclimatic importance. This is being done by applying a suite of relatively new geochemical tools, which are: the uranium-series comminution age method, excess thorium-230 for determining sediment focusing factors, optically stimulated luminescence dating, and compound-specific carbon-14 dating, as well as conventional neodymium and strontium isotopes for provenance. The sum of the information obtained by conducting these measurements will provide quantitative marine sediment transport and storage timescales, insight into the related drift-forming processes, and a better understanding of how to interpret multiproxy paleoclimate records. This has direct relevance for understanding the Earth?s climate system, which presently is of societal concern.