Metamorphic diogenite Grosvenor Mountains 95555: Mineral chemistry of orthopyroxene and spinel and comparisons to the diogenite suite

Authors

  • J. J. PAPIKE,

    Corresponding author
    1. Institute of Meteoritics, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131-1126, USA
    Search for more papers by this author
  • C. K. SHEARER,

    1. Institute of Meteoritics, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131-1126, USA
    Search for more papers by this author
  • M. N. SPILDE,

    1. Institute of Meteoritics, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131-1126, USA
    Search for more papers by this author
  • J. M. KARNER

    1. Institute of Meteoritics, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131-1126, USA
    Search for more papers by this author

jpapike@unm.edu

Abstract

Abstract— Grosvenor Mountains (GRO) 95555 is a relatively newly discovered and unique metamorphic diogenite. It does not show the usual brecciated appearance of other diogenites or wide compositional variability of orthopyroxene or spinel. Electron microprobe analysis (EMPA) and secondary ion mass spectrometer (SIMS) analysis of orthopyroxene and EMPA of spinel show limited compositional variability. Compositions for orthopyroxene for Fe/(Fe + Mg) atomic, Al, Zr, Y, and Yb fall in the middle of the compositional ranges of the diogenite suite. Apparently, GRO 95555 formed at sufficient depth or location to escape brecciation by meteorite bombardment and in a thermal regime that led to high-grade metamorphism resulting in homogeneous mineral compositions.

Ancillary