An occurrence of metastable cristobalite in high-pressure garnet Granulite

R.S. Darling; I.-M. Chou; R.J. Bodnar

doi:10.1126/science.276.5309.91

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An occurrence of metastable cristobalite in high-pressure garnet Granulite

R.S. Darling·I.-M. Chou·R.J. Bodnar

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Abstract

High-pressure (0.8 gigapascals) granulite facies garnet from Gore Mountain, New York, hosts multiple solid inclusions containing the low- pressure silica polymorph cristobalite along with albite and minor ilmenite. Identification of cristobalite is based on Raman spectra, electron microprobe analysis, and microthermometric measurements on the ??/?? phase transformation. The cristobalite plus albite inclusions may have originated as small, trapped samples of hydrous sodium-aluminum-siliceous melt. Diffusive loss of water from these inclusions under isothermal, isochoric conditions may have resulted in a large enough internal pressure decrease to promote the metastable crystallization of cristobalite.

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R.S. Darling, I.-M. Chou, R.J. Bodnar. 1997. An occurrence of metastable cristobalite in high-pressure garnet Granulite. https://doi.org/10.1126/science.276.5309.91

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