The temperature and pressure dependence of Ni partitioning between olivine and MgO-rich silicate melt

Melting of the Hawaiian plume occurs at high T and P (e.g., ~1600°C, 4 GPa [1]), and so it is important that Ni partitioning data are obtained at these conditions to test competing hypothesis for the high Ni contents of Hawaiian olivines. Available data for DNi (NiO^(°1)/NiO^(liq)) are, however, dominated by the results of 1-atm experiments where T and MgO^(liq) are strongly correlated, making it difficult to separate the effects of liquid composition from that of T on DNi. Indeed, most simple parameterizations of D_(Ni) rely on MgO^(liq) as the principal independent variable [2, 3]. This approach, although adequate for many applications, is problematic for addressing Ni partitioning in the mantle because liquids with the same MgO content can coexist with olivine over a range of P and T. We studied Ni partitioning in olivine-liquid pairs at near constant MgO^(liq) over a significant P-T range in order to separate the effects of P, T, and liquid composition on D_(Ni).