The CaCO3–Fe interaction: Kinetic approach for carbonate subduction to the deep Earth's mantle

N. S. Martirosyan, T. Yoshino, A. Shatskiy, A. D. Chanyshev, K. D. Litasov

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    19 Citations (Scopus)

    Abstract

    The CaCO3–Fe0 system, as a model for redox reactions between carbonates and reduced lithologies at the slab-mantle interface during subduction or at core-mantle boundary, was investigated systematically at temperatures from 650 to 1400 °C and pressures from 4 to 16 GPa using multianvil apparatus. CaCO3 reduction via reaction: 3 CaCO3 (aragonite) + 13 Fe0 (metal) = Fe7C3 (carbide) + 3 CaFe2O3 (Ca-wüstite) was observed. The thickness of the reaction-product layer (Δx) increases linearly with the square root of time in the time-series experiments (t), indicating diffusion-controlled process. The reaction rate constant (k = Δx2/2t) is log-linear relative to 1/T. Its temperature dependences was determined to be k [m2/s] = 2.1 × 10−7exp(−162[kJ/mol]/RT) at 4–6 GPa and k [m2/s] = 2.6 × 10−11exp(−65[kJ/mol]/RT) at 16 GPa. The sluggish kinetics of established CaCO3–Fe0 interaction suggests that significant amount of carbonates could survive during subduction from metal saturation boundary near 250 km depth down to the transition zone and presumably to the lower mantle if melting of carbonates is not involved.

    Original languageEnglish
    Pages (from-to)1-9
    Number of pages9
    JournalPhysics of the Earth and Planetary Interiors
    Volume259
    DOIs
    Publication statusPublished - Oct 1 2016

    Keywords

    • Ca-carbonate
    • Ca-wüstite
    • Iron carbide
    • Kinetics
    • Redox reaction
    • Subducted slab

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Geophysics
    • Physics and Astronomy (miscellaneous)
    • Space and Planetary Science

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