Formation of metastable assemblages and mechanisms of the grain-size reduction in the postspinel transformation of Mg2SiO4

Tomoaki Kubo; Eiji Ohtani; Takumi Kato; Satoru Urakawa; Akio Suzuki; Yuichi Kanbe; Ken Ichi Funakoshi; Wataru Utsumi; Kiyoshi Fujino

doi:10.1029/1999GL008430

Formation of metastable assemblages and mechanisms of the grain-size reduction in the postspinel transformation of Mg₂SiO₄

Tomoaki Kubo, Eiji Ohtani, Takumi Kato, Satoru Urakawa, Akio Suzuki, Yuichi Kanbe, Ken Ichi Funakoshi, Wataru Utsumi, Kiyoshi Fujino

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33 Citations (Scopus)

Abstract

An in situ X-ray observation of the postspinel transformation kinetics was made using intense synchroton radiation. We confirmed that Mg₂SiO₄ spinel transforms into fine lamellae of SiO₂ stishovite and periclase, and/or MgSiO₃ ilmenite and periclase as an intermediate step in the postspinel transformation. These metastable assemblages eventually disappear and form the stable assemblages of MgSiO₃ perovskite and periclase. Initial grain size just after the postspinel transformation drastically changes with overpressure. Viscosity of the subducting slab into the lower mantle, which is thought to be deformed by grain-size-sensitive creep, would depend on overpressure needed for the postspinel transformation at geological time scale.

Original language	English
Pages (from-to)	807-810
Number of pages	4
Journal	Geophysical Research Letters
Volume	27
Issue number	6
DOIs	https://doi.org/10.1029/1999GL008430
Publication status	Published - Mar 15 2000
Externally published	Yes

All Science Journal Classification (ASJC) codes

Geophysics
Earth and Planetary Sciences(all)

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10.1029/1999GL008430

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title = "Formation of metastable assemblages and mechanisms of the grain-size reduction in the postspinel transformation of Mg2SiO4",

abstract = "An in situ X-ray observation of the postspinel transformation kinetics was made using intense synchroton radiation. We confirmed that Mg2SiO4 spinel transforms into fine lamellae of SiO2 stishovite and periclase, and/or MgSiO3 ilmenite and periclase as an intermediate step in the postspinel transformation. These metastable assemblages eventually disappear and form the stable assemblages of MgSiO3 perovskite and periclase. Initial grain size just after the postspinel transformation drastically changes with overpressure. Viscosity of the subducting slab into the lower mantle, which is thought to be deformed by grain-size-sensitive creep, would depend on overpressure needed for the postspinel transformation at geological time scale.",

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T1 - Formation of metastable assemblages and mechanisms of the grain-size reduction in the postspinel transformation of Mg2SiO4

AU - Kubo, Tomoaki

AU - Ohtani, Eiji

AU - Kato, Takumi

AU - Urakawa, Satoru

AU - Suzuki, Akio

AU - Kanbe, Yuichi

AU - Funakoshi, Ken Ichi

AU - Utsumi, Wataru

AU - Fujino, Kiyoshi

PY - 2000/3/15

Y1 - 2000/3/15

N2 - An in situ X-ray observation of the postspinel transformation kinetics was made using intense synchroton radiation. We confirmed that Mg2SiO4 spinel transforms into fine lamellae of SiO2 stishovite and periclase, and/or MgSiO3 ilmenite and periclase as an intermediate step in the postspinel transformation. These metastable assemblages eventually disappear and form the stable assemblages of MgSiO3 perovskite and periclase. Initial grain size just after the postspinel transformation drastically changes with overpressure. Viscosity of the subducting slab into the lower mantle, which is thought to be deformed by grain-size-sensitive creep, would depend on overpressure needed for the postspinel transformation at geological time scale.

AB - An in situ X-ray observation of the postspinel transformation kinetics was made using intense synchroton radiation. We confirmed that Mg2SiO4 spinel transforms into fine lamellae of SiO2 stishovite and periclase, and/or MgSiO3 ilmenite and periclase as an intermediate step in the postspinel transformation. These metastable assemblages eventually disappear and form the stable assemblages of MgSiO3 perovskite and periclase. Initial grain size just after the postspinel transformation drastically changes with overpressure. Viscosity of the subducting slab into the lower mantle, which is thought to be deformed by grain-size-sensitive creep, would depend on overpressure needed for the postspinel transformation at geological time scale.

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Formation of metastable assemblages and mechanisms of the grain-size reduction in the postspinel transformation of Mg₂SiO₄

Abstract

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