Origin of Cratonic Peridotite and Komatiite: Evidence for Melting in the Wet Archean Mantle.:Evidence for Melting in the Wet Archean Mantle

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概要

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• We have conducted melting experiments of pyrolite containing 1 and 2wt.% of water at 6.5GPa by a multianvil high pressure apparatus. We observed melting at temperatures above 1550°C and 1700°C for pyrolite+2%H2O and pyrolite+1%H2O respectively at 6.5GPa. A small amount of water reduces the solidus temperature by 250-100°C. Another important observation is expansion of the stability field of orthopyroxene above the solidus, and reduction of the stability field of olivine+liquid. The present observation of expansion of the orthopyroxene stability field above the solidus at 6.5GPa implies that the harzburgite residue can be formed by partial melting of the primitive mantle under the hydrous conditions at the depth of around 200km. Hydrous melting is a key process to fill the missing link between the cratonic peridotite and komatiite; i.e., cratonic peridotite was formed as a residue of the komatiite extraction in a wet Archean mantle.

• 日本学士院の論文

著者

• Ohtani Eiji

  Institute Of Mineralogy Petrology And Economic Geology Faculty Of Science Tohoku University

• KATO Takumi

  Institute of Geosciences, University of Tsukuba

• MIBE Kenji

  Earthquake Research Institute, University of Tokyo

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• Application of FIB system to ultra-high-pressure Earth science
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• Flotation of Olivine in the Peridotite Melt at High Pressure.
• Origin of Cratonic Peridotite and Komatiite: Evidence for Melting in the Wet Archean Mantle.:Evidence for Melting in the Wet Archean Mantle

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