Contributions to Mineralogy and Petrology

, Volume 145, Issue 4, pp 391–405

Mineral/melt partitioning of trace elements during hydrous peridotite partial melting

Authors

    • Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of Technology
    • Division of Geological and Planetary SciencesCalifornia Institute of Technology
    • Department of Geology and GeophysicsWoods Hole Oceanographic Institution
  • Adam J. R. Kent
    • Division of Geological and Planetary SciencesCalifornia Institute of Technology
    • Analytical and Nuclear Chemistry DivisionLawrence Livermore National Laboratory
    • Department of GeosciencesOregon State University
  • Timothy L. Grove
    • Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of Technology
  • Ian D. Hutcheon
    • Analytical and Nuclear Chemistry DivisionLawrence Livermore National Laboratory
  • Edward M. Stolper
    • Division of Geological and Planetary SciencesCalifornia Institute of Technology
Original Paper

DOI: 10.1007/s00410-003-0447-0

Cite this article as:
Gaetani, G.A., Kent, A.J.R., Grove, T.L. et al. Contrib Mineral Petrol (2003) 145: 391. doi:10.1007/s00410-003-0447-0

Abstract

This experimental study examines the mineral/melt partitioning of incompatible trace elements among high-Ca clinopyroxene, garnet, and hydrous silicate melt at upper mantle pressure and temperature conditions. Experiments were performed at pressures of 1.2 and 1.6 GPa and temperatures of 1,185 to 1,370 °C. Experimentally produced silicate melts contain up to 6.3 wt% dissolved H2O, and are saturated with an upper mantle peridotite mineral assemblage of olivine+orthopyroxene+clinopyroxene+spinel or garnet. Clinopyroxene/melt and garnet/melt partition coefficients were measured for Li, B, K, Sr, Y, Zr, Nb, and select rare earth elements by secondary ion mass spectrometry. A comparison of our experimental results for trivalent cations (REEs and Y) with the results from calculations carried out using the Wood-Blundy partitioning model indicates that H2O dissolved in the silicate melt has a discernible effect on trace element partitioning. Experiments carried out at 1.2 GPa, 1,315 °C and 1.6 GPa, 1,370 °C produced clinopyroxene containing 15.0 and 13.9 wt% CaO, respectively, coexisting with silicate melts containing ~1–2 wt% H2O. Partition coefficients measured in these experiments are consistent with the Wood-Blundy model. However, partition coefficients determined in an experiment carried out at 1.2 GPa and 1,185 °C, which produced clinopyroxene containing 19.3 wt% CaO coexisting with a high-H2O (6.26±0.10 wt%) silicate melt, are significantly smaller than predicted by the Wood-Blundy model. Accounting for the depolymerized structure of the H2O-rich melt eliminates the mismatch between experimental result and model prediction. Therefore, the increased Ca2+ content of clinopyroxene at low-temperature, hydrous conditions does not enhance compatibility to the extent indicated by results from anhydrous experiments, and models used to predict mineral/melt partition coefficients during hydrous peridotite partial melting in the sub-arc mantle must take into account the effects of H2O on the structure of silicate melts.

Copyright information

© Springer-Verlag 2003