Morphological stability of hydrous liquid droplets at grain boundaries of eclogite minerals in the deep upper mantle

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Author(s)

    • MATSUKAGE Kyoko N.
    • Earth and Planetary Sciences, Tokyo Institute of Technology|Present address: Center for Fundamental Education, Teikyo University of Science

Abstract

<p>The morphological stability of hydrous liquid droplets at grain boundaries of eclogite minerals in the basaltic part of a subducting slab were investigated based on experimental constraints for the dihedral angles. We measured the dihedral angles in the eclogite–H<sub>2</sub>O system at a temperature of 1000 °C and at pressures ranging from 4 to 16 GPa. The dihedral angle of hydrous liquid versus garnet–garnet (<i>θ</i><sub>GG–L</sub>) increased with increasing pressure from 46° at 4 GPa to 66° at 12 GPa, although it showed a weak decreasing trend at pressures higher than 12 GPa. The dihedral angle of hydrous liquid versus clinopyroxene–clinopyroxene (<i>θ</i><sub>CC–L</sub>) was almost constant with increasing pressure (61 and 59° at 4 and 10 GPa, respectively). The dihedral angle of hydrous liquid versus garnet–clinopyroxene (<i>θ</i><sub>GC–L</sub>) was 73–76° at 4–10 GPa, and it was always higher than <i>θ</i><sub>GG–L</sub> and <i>θ</i><sub>CC–L</sub>. By applying the morphological stability criteria for liquid in a system with two solid phases (garnet and clinopyroxene) and bond percolation theory for a three–dimensional lattice of tetracoordination, we found that the hydrous liquid was isolated at the grain edges and corners of eclogite minerals in the cold slab under a wide range of pressure conditions of the upper mantle from 4–14 GPa when the grain size of garnet was equal to that of clinopyroxene. Thus, basaltic crust containing hydrous liquid droplets may carry water to the lowermost upper mantle and the mantle transition zone when the slab is cold.</p>

Journal

  • Journal of Mineralogical and Petrological Sciences

    Journal of Mineralogical and Petrological Sciences 112(6), 346-358, 2017

    Japan Association of Mineralogical Sciences

Codes

  • NII Article ID (NAID)
    130006287887
  • Text Lang
    ENG
  • ISSN
    1345-6296
  • Data Source
    J-STAGE 
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