SUPERHEATING EFFECTS ON METAL-SILICATE PARTITIONING OF SIDEROPHILE ELEMENTS

Liquid metal-liquid silicate partition coefficients for several elemen ts at 100 kilobars and temperatures up to about 3000 kelvin in carbon capsules experimentally converge on unity with increasing temperature. The sense of change of the partition coefficients with temperature re sembles the extrapolation of Murthy and may partially contribute to, b ut by no means provide a complete resolution of, the ''excess'' sidero phile problem in the Earth's mantle. Sulfur and perhaps carbon success fully compete with oxygen for sites in the metallic liquid at these te mperatures and pressures. This observation casts doubt upon the hypoth esis that oxygen is the light element in the Earth's core.