Geochemistry of Mo, U, V, and Re in Continental Margin Sediments

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9402830 EMERSON This is a study of the geochemistry of Mo, V, U, and Re in a series of cores on the continental margins of the Atlantic, Pacific, and Indian Oceans. These elements are conservative, or nearly so, in sea water and highly enriched in sediments overlain by anoxic or very low oxygen-content bottom water. The concentration of these elements in sea water may have changed in the past in response to the changing area of anoxic sediments in the ocean. Quantitative interpretation of the changes, however, requires better understanding of how these elements behave in continental margin sediments. Thus, their burial rates over the past 20 Ka. will be studied in five box-core transects from the continental shelf to the deep sea. Cores from the Atlantic and Pacific Ocean continental margins were raised on previous pore water investigations, and sediments from a transect across the oxygen minimum zone in the Arabian Sea to be sampled in the Indian Ocean Program in 1995, will be provided from other investigations. In the latter study, a year-long suite of sediment trap samples will also be analyzed. All transects cross a strong gradient in sediment redox conditions, and some also experience dramatic changes in the level of bottom water oxygen concentration. Both the organic carbon rain rate to the sediment-water interface and the bottom water oxygen concentration influence the burial rate of these metals and will be determined.