Partitioning of Tungsten and Molybdenum Between Metallic Liquid and Silicate Melt

Science  17 Nov 1995:
Vol. 270, Issue 5239, pp. 1186-1189
DOI: 10.1126/science.270.5239.1186


The “excess” of siderophile elements in Earth's mantle is a long-standing problem in understanding the evolution of Earth. Determination of the partitioning behavior of tungsten and molybdenum between liquid metal and silicate melt at high pressure and temperature shows that partition coefficients (Dmetal/silicate) vary by two orders of magnitude depending on whether metal segregated from a basaltic or peridotitic melt. This compositional dependence is likely a response to changes in the degree of polymerization of the silicate melt caused by compositional variations of the network-modifying cations Mg2+and Fe2+. Silicate melt compositional effects on partition coefficients for siderophile elements are potentially more important than the effects of high pressure and temperature.