Growth of ringwoodite reaction rims from MgSiO3 perovskite and periclase at 22.5 GPa and 1,800 °C

Akira Shimojuku, Asmaa Boujibar, Daisuke Yamazaki, Takashi Yoshino, Naotaka Tomioka, Junshan Xu

    Research output: Contribution to journalArticlepeer-review

    5 Citations (Scopus)

    Abstract

    The growth rate of ringwoodite reaction rims between MgSiO3 perovskite and periclase was investigated at 22.5 GPa and 1,800 °C for 1-24 h using the Kawai-type high-pressure apparatus. The reaction was likely to proceed by a diffusion-controlled mechanism in which the dominant diffusion mechanism was grain-boundary diffusion. The reaction constant (the width of the ringwoodite reaction rim squared divided by time) determined from these experiments was between 1.3 × 10-15 and 5.6 × 10-15 m2/s. A Pt inert marker experiment indicated that the MgO component migrated faster than the SiO2 component in ringwoodite. Thus, either Mg or O having the slower diffusion rate controlled the reaction. Because previous diffusion studies have shown that diffusion rates of O are slower than those of Mg, O would be a rate-controlling element for ringwoodite formation from MgSiO3 perovskite and periclase. The growth rate appeared to be too fast to explain the observed topographic rise (~10 km) inside mantle plumes at the 660-km discontinuity.

    Original languageEnglish
    Pages (from-to)555-567
    Number of pages13
    JournalPhysics and Chemistry of Minerals
    Volume41
    Issue number7
    DOIs
    Publication statusPublished - Jul 2014

    Keywords

    • Diffusion
    • Growth kinetics
    • Post-spinel transformation
    • Reaction rim
    • Ringwoodite

    ASJC Scopus subject areas

    • Materials Science(all)
    • Geochemistry and Petrology

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