Geochemical Studies of Ocean Basin Evolution

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The P.I. has carried out significant research on isotope and trace element geochemistry of EPR (9o30'N, 13p30'-15oN), MAR(36oN), the Gorda Ridge, President Jackson Seamounts, & S. Atlantic hot spot tracks. He now wishes to continue this effort and analyze trace element abundances in basalts from both Pacific and Atlantic oceans with the objective of characterizing source compositions and magmatic processes in the two ridge systems that have very different spreading rates. Additionally, he will analyze zero age and somewhat older basalts from the EPR area in order to evaluate the processes which cause temporal geochemical variations in magma evolution along the EPR. An important thrust of the present project is the determination of the U, Th and Pb abundances of oceanic basalts from EPR, FAMOUS, and some ocean island areas. The purpose is to characterize U/Pb and Th/U ratios of mantle plumes vs. the depleted N-MORB reservoir. The ultimate goal of this project is to quantify geochemical models of mantle sources (plumes, depleted reservoirs) and the processes which affect crust formation at mid-oceanic ridges.