This program involves experimental studies of the partitioning of siderophile and other elements between lithophile phases and silicate melts at pressures varying from 1 bar to in excess of 200 kbars and temperatures varying from 1300oC to in excess of 2300oC. Knowledge of these partition coefficients is essential to the interpretation of elemental systematics in the mantle and mantle- derived materials and specifically bears on the question of the early differentiation of the Earth. These experiments also bear directly on the thermodynamics and economic geology of the platinum group elements (PGE). During the next award period, the P.I.'s (i) continue ultrahigh pressure experiments between olivine/melt, majorite/melt, and Mg- perovskite/melt phase pairs, including ultrahigh pressure reversal experiments; (ii) continue the systematic study of noble melt solubilities in silicate melts and partitioning between coexisting phases as functions of intensive variables; and (iii) conduct experiments investigating the partitioning of Ga and Ge between garnet/melt and clinopyroxene/melt pairs. The results f the experiments will be applied to understanding the early thermal history and differentiation of the Earth and to the thermodynamics and economic geology of the PGE.
