An Experimental Study of Trace Element Partitioning between Peridotite Minerals and Alkaline Basaltic Melts at 1250°C and 1 GPa: Crystal and Melt Composition Impacts on Partition Coefficients

Abstract Peridotite–magma interaction is important in establishing magma pathways through the mantle and metasomatism of lithospheric mantle. Reactions that consume orthopyroxene produce olivine clinopyroxene are particular interest because these reactions should lead to a redistribution trace elements between solid melt phases at equilibrium. This study examines silica-undersaturated alkaline basalt (basanite) with range peridotite compositions from dunite, harzburgite wehrlite 1250°C 1 GPa. Our experiments used natural concentration starting materials which allowed us measure mineral—olivine partition coefficients for Rb, Ca, Co, Sr, Sc, Ct, Y, Ti, V Zr. For orthopyroxene—and clinopyroxene—melt we additionally measured partitioning Cs, Ba, all rare earth (REE; except Pm), Hf, Th, U, Nb Ta. We show there subtle variations coefficients, particularly REEs related bulk composition system. also exception cations can have multiple valence states, e.g. vanadium, lattice strain model double fit routine gives excellent agreement calculated experimentally determined coefficients. The allows examine effect mineral on such preference M1 M2 sites pyroxenes. Although our results similar those previous studies, two main differences: first complete set every element measurable by LA-ICPMS material, where studies may be missing one or more middle REE pyroxenes Second, although comparable this typically factor 2–3 lower study. note correlations coefficient olivine, orthopyroxene, glass (melt). relation suggests some further development needed. Finally, predicted parameterized models clinopyroxene–melt partitioning, however, unresolved differences result substitution mechanisms vs. part coexisting melt.