EAR-9505215 Lassiter, John C. Re-Os isotopic data from a suite of cogenetic basalts from Hawaii will be used to improve understanding of the behavior of Re and Os during melting of the mantle and melt transport through the crust. Because of the analytical difficulties in measuring Re and Os abundances in very low-concentration materials, it is only in the past few years that it has been possible to consider application of Re-Os systematics to problems of mantle convection and crustal evolution. Unlike other isotopic systems currently used to address these fundamental problems, Os behaves compatibly during melting. As a result, 187Os/186Os ratios are extremely sensitive to relative contributions of evolved and primitive materials. This project will (1) constrain the chemical behavior of Os (and Re) during melt production; (2) document the interaction of melts with the surrounding mantle and crust during transport to the surface; and (3) determine the degree of Os isotopic heterogeneity in the basalts and the relationship to possible mantle heterogeneities. These advances in the understanding of Re-Os systematics will permit their use in advancing the overall understanding of mantle evolution.
