9526329 Walker Despite its importance in understanding the chemical evolution of the Earth, the Os isotopic composition of the mantle is poorly constrained. This is to continue characterization of the Os isotopic composition of various mantle domains through time, via the analysis of ultramafic rocks that are otherwise geochemically and isotopically well-characterized, and that have relatively high Os concentrations and low Re/Os ratios. Specific targets for analysis will be ultramafic magmatic systems that represent upper oceanic lithospheric materials, and materials derived from likely mantle plumes. Both whole rock samples and mineral separates will be analyzed from each location. The resulting information should lead to: 1) a better understanding of how Os has evolved in plume and upper mantle reservoirs, and 2) provide insights into where Re and Os are sited in these types of rocks and what phases or combination of phases provide the most useful information about initial isotopic compositions.
