Melting experiments on peridotite to lowermost mantle conditions

Shigehiko Tateno, Kei Hirose, Yasuo Ohishi

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    52 Citations (Scopus)

    Abstract

    Melting experiments on a pyrolitic mantle material were performed in a pressure range from 34 to 179GPa based on laser-heated diamond-anvil cell (DAC) techniques. The textural and chemical characterizations of quenched samples were made by using field-emission-type electron microprobe (FE-EPMA). Melts formed by 46 to 77wt.% partial melting in this study were ultrabasic in composition and became more depleted in SiO2 and more enriched in FeO with increasing pressure. Melting textures indicate that the liquidus phase changed from ferropericlase to MgSiO3-rich perovskite at least above 34GPa and further to post-perovskite. The first phase to melt (disappear) changed from CaSiO3 perovskite to (Mg,Fe)O ferropericlase between 68 and 82GPa. The stability of ferropericlase above solidus temperature shrinks with increasing pressure (melting last below 34GPa and first 82GPa), resulting in higher (MgO+FeO)/SiO2 ratio in partial melt at higher pressure. Additionally, the Fe-Mg distribution coefficients (KD) between perovskite/post-perovskite and melt decreased considerably with increasing pressure, leading to strong Fe-enrichment in partial melts. It supports dense partial melts in a deep lower mantle, which migrate downward to the core mantle boundary (CMB). Key Points Melting relations and chemical compositions of melt and solid to CMB conditions Partial melt become more ultrabasic with increasing pressure Strong Fe enrichment in partial melts formed at deep lower mantle

    Original languageEnglish
    Pages (from-to)4684-4694
    Number of pages11
    JournalJournal of Geophysical Research: Solid Earth
    Volume119
    Issue number6
    DOIs
    Publication statusPublished - Jun 2014

    Keywords

    • diamond-anvil cell
    • lower mantle
    • melting
    • peridotite

    ASJC Scopus subject areas

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

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