Experimentally determined partitioning of high field strength- and selected transition elements between spinel and basaltic melt

Partition coefficients for the elements Ta, Nb, Hf, Zr, Sc, V, Ga, Zn and Co have been determined by laser ablation ICP-MS and/or electron microprobe between spinel and melt using an alkali olivine basalt at 1 atm. The D ^{sp lq} for high field strength elements (HFSE) are uniform (D ^{sp lq} _Nb = 0.08, D ^{sp lq} _Ta = 0.06, D ^{sp lq} _Hf = 0.05, D ^{sp lq} _Zr = 0.06), negating the possibility of intra-HFSE fractionation during partial melting or fractional crystallization processes. Results for D ^{sp lq} _V continue an approximately linear trend of decreasing D ^{sp lq} _V with increasing f_O2 from D ^{sp lq} _V = 68 at IW from previous studies to values of D ^{sp lq} _V = 0.09 at f_O2 = air. D ^{sp lq} _Sc is also f_O2 dependent (0.24-0.56 with increasing f_O2), whereas D ^{sp lq} _Ga is constant at 3.2. A compositional dependence of partitioning behaviour was found for the Ti-poor solid-solution series between chromite-and magnetite-rich spinels in the log f_O2 range from air to FMQ - 1 for Co, Zn and Sc. Zn and Co showed deviation from Henry's law behaviour. An approximate value for D ^{sp lq} _Zn of 4.5 agrees well with the observed partitioning in natural peridotites, but is much larger at lower temperatures. Cobalt partitioning shows a strong negative correlation with temperature and is complicated by f_O2 effects.