The Eclogite-Garnetite transformation in the MORB + H2O system

Kazuaki Okamoto, Shigenori Maruyama

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    83 Citations (Scopus)


    To decipher phase relations of oceanic crust in the coldest slab at the mantle transition zone, multi-anvil experiments were conducted in the MORB+H2O system at pressures of 10-19 GPa, and temperatures of 700-1500 °C. Garnet and stishovite were recognized in all run charges. Above 15 GPa, garnet drastically increases NaSi (Na2MSi5O12) component (M = Ca, Mg, Fe2+), jadeite occurs instead of omphacite. Na-, K-hollandite containing 7 mol% NaAlSi3O8 and Ca-perovskite with 60 mol% CaTiO3, were observed at P> 17 GPa. With decomposition of omphacite and increase of modal ratio of garnet, there is a sharp increase of density at 440 km. The density increase due to appearance of Ca-perovskite at 570 km, is estimated approximately 100 km shallower than that of previous estimation.

    Original languageEnglish
    Pages (from-to)283-296
    Number of pages14
    JournalPhysics of the Earth and Planetary Interiors
    Issue number1-2
    Publication statusPublished - Aug 16 2004


    • Ca-perovskite
    • Eclogite-garnetite transformation
    • Jadeite
    • Na(Ca,Mg,Fe SiO-component in garnet
    • UHP experiments

    ASJC Scopus subject areas

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


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