Phase III of this project is a collaborative, multidisciplinary extension of earlier work. The PI's will combine isotope geochemistry with experimental petrology/geochemistry. Objectives are to: 1) Continue to precisely measure the 186Os/188Os of a variety of possibly plume-derived rocks for which Pb-Os relations suggest the involvement of non-crustal 187Os-enriched materials, and assess if there is a positive relation between 186Os and 187Os enrichment. 2) Experimentally examine the partitioning of Pt, Re and Os between liquid and solid metal phases at increasingly higher pressures and temperatures. The goal of this research is to assess whether the partitioning of Pt, Re and Os behave in larger planetary bodies as they do in asteroidal cores. 3) Precisely and accurately measure the concentrations of Pt and Pt/Os in a variety of mantle and crustal materials that may be recycled into the mantle. The goal of this aspect of the research is to confirm or deny the preliminary evidence that suggests recycling of crustal materials into the mantle little affects the Pt/Os ratio of mantle-crust mixtures.
