Growth of ringwoodite reaction rims from MgSiO3 perovskite and periclase at 22.5 GPa and 1,800 °C - Université Clermont Auvergne Accéder directement au contenu
Article Dans Une Revue Physics and Chemistry of Minerals Année : 2014

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

Résumé

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.
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Dates et versions

hal-01133630 , version 1 (19-03-2015)

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Akira Shimojuku, Asmaa Boujibar, Daisuke Yamazaki, Takashi Yoshino, Naotaka Tomioka, et al.. Growth of ringwoodite reaction rims from MgSiO3 perovskite and periclase at 22.5 GPa and 1,800 °C. Physics and Chemistry of Minerals, 2014, 41, pp.555-567. ⟨10.1007/s00269-014-0669-x⟩. ⟨hal-01133630⟩
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