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 m) were analyzed using both SIMS and LA-ICP-MS, with a spatial resolution of 15 to 50 m. Rhenium, Au and Pd were all found to be incompatible in Cr-rich spinel (DRe sp/melt 0.0012–0.21, DAu sp/melt 0.076, DPd sp/melt 0.14), whereas Rh, Ru and Ir were all found to be highly compatible (DRh sp/melt 41–530, DRu sp/melt 76–1143, DIr sp/melt 5–22000). Rhenium, Pd, Au and Ru were all found to be incompatible in olivine (DRe oliv/melt 0.017–0.073, DPd oliv/melt 0.12, DAu oliv/melt 0.12, DRu oliv/melt 0.23), Re is incompatible in orthopyroxene and clinopyroxene (DRe opx/melt 0.013, DRe cpx/melt 0.18–0.21), and Pt is compatible in clinopyroxene (DPt cpx/melt 1.5). The results are compared to and combined with previous work on HSE partitioning among spinel-structured oxides, and applied to some natural magmatic suites to demonstrate consistency. Copyright © 2004 Elsevier Ltd