Partitioning of Ru, Rh, Pd, Re, Ir, and Au between Cr-bearing spinel, olivine, pyroxene and silicate melts

A series of high temperature experiments was undertaken to study partitioning of several highly siderophile elements (HSE; Ru, Rh, Pd, Re, Os, Ir, Pt and Au) between Cr-rich spinel, olivine, pyroxene and silicate melt. Runs were carried out on a Hawaiian ankaramite, a synthetic eucrite basalt, and a DiAn eutectic melt, at one bar, 19 kbar, and 20 kbar, respectively, in the temperature range of 1200 to 1300 C, at oxygen fugacities between the nickel-nickel oxide (NNO) and hematite-magnetite (HM) oxygen buffers. High oxygen fugacities were used to suppress the formation of HSE-rich nuggets in the silicate melts. The resulting oxide and silicate crystals (<100 mum) were analyzed using both SIMS and LA-ICP-MS, with a spatial resolution of 15 to 50 mum. Rhenium, Au and Pd were all found to be incompatible in Cr-rich spinel (D-Re(sp/melt) = 0.0012-0.21, D-Au(sp/melt) = 0.076, D-Pd(sp/melt) = 0.14), whereas Rh, Ru and It were all found to be highly compatible (D-Rh(sp/melt) = 41-530, D-Ru(sp/melt) = 76-1143, D-Ir(sp/melt) = 5-22000). Rhenium, Pd,Au and Ru were all found to be incompatible in olivine (D-Re(oliv/melt) = 0.017-0.073, D-Pd(oliv/melt) = 0.12, D-Au(oliv/melt) = 0.12, D-Ru(oliv/melt) = 0.23), Re is incompatible in orthopyroxene and clinopyroxene (D-Re(opx/melt) = 0.013, D-Re(cpx/melt) = 0.18-0.21), and Pt is compatible in clinopyroxene (D-Pt(cpx/melt) = 1.5). The results are compared to and combined with previous work on HSE partitioning among spinet-structured oxides, and applied to some natural magmatic suites to demonstrate consistency. Copyright (C) 2004 Elsevier Ltd.