High-Pressure and High-Temperature in situ X-ray Diffraction Study of Natural Garnet (Mg0. 72Fe0. l7Ca0. 11) 3Al2Si3O12 up to 32 GPa and 2000 K Using MA8-Type Apparatus

K. Oguri; N. Funamori; T. Uchida; T. Yagi; N. Miyajima; K. Fujino

doi:10.4131/jshpreview.7.59

High-Pressure and High-Temperature in situ X-ray Diffraction Study of Natural Garnet (Mg_{0. 72}Fe_{0. l7}Ca_{0. 11}) ₃Al₂Si₃O₁₂ up to 32 GPa and 2000 K Using MA8-Type Apparatus

K. Oguri, N. Funamori, T. Uchida, T. Yagi, N. Miyajima, K. Fujino

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Keywords: natural garnet, in situ x-ray observation, MA8-type apparatus, transition rate

JOURNAL FREE ACCESS

1998 Volume 7 Pages 59-61

DOI https://doi.org/10.4131/jshpreview.7.59

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Abstract

Breakdown reaction of natural garnet was studied by an in situ x-ray observation using an MA8-type multi-anvil apparatus up to about 32 GPa. Natural garnet with a composition (Mg_{0. 72}Fe_{0. l7}Ca_{0. 11}) ₃Al₂Si₃O₁₂ breaks down at a pressure between 24 and 27 GPa to a mixture of sub-aluminous orthorhombic silicate perovskite, stishovite, Al-rich phase with unknown structure, and possibly CaSiO₃ perovskite. The unreacted garnet was observed even after heating the sample at 31. 7 GPa and 2000 K for 6000 sec. This result implies that the transition rate of the garnet is lower than that of Al-free system such as olivine and pyroxene.

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