Two-stage spin transition of iron in FeAl-bearing phase D at lower mantle

Xiang Wu, Ye Wu, Jung Fu Lin, Jin Liu, Zhu Mao, Xinzhuan Guo, Takashi Yoshino, Catherine McCammon, Vitali B. Prakapenka, Yuming Xiao

    Research output: Contribution to journalArticlepeer-review

    9 Citations (Scopus)

    Abstract

    Hydrous magnesium silicate phase D plays a key role in the transport of water from the upper to the lower mantle via subducted slabs. Here we report pressure dependence hyperfine and lattice parameters of FeAl-bearing phase D up to megabar pressures using synchrotron nuclear forward scattering and X-ray diffraction in a diamond anvil cell at room temperature. FeAl-bearing phase D undergoes a two-stage high-spin to low-spin transition of iron for Fe2+ at 37–41 GPa and for Fe3+ at 64–68 GPa. These transitions are accompanied by an increase in density and a significant softening in the bulk modulus and bulk velocity at their respective pressure range. The occurrence of the dense low-spin FeAl-bearing phase D with relatively high velocity anisotropies in deep-subducted slabs can potentially contribute to small-scale seismic heterogeneities in the middle-lower mantle beneath the circum-Pacific area.

    Original languageEnglish
    Pages (from-to)6411-6420
    Number of pages10
    JournalJournal of Geophysical Research: Solid Earth
    Volume121
    Issue number9
    DOIs
    Publication statusPublished - Sep 1 2016

    Keywords

    • lower mantle
    • phase D
    • spin transition of iron

    ASJC Scopus subject areas

    • Geophysics
    • Geochemistry and Petrology
    • Earth and Planetary Sciences (miscellaneous)
    • Space and Planetary Science

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