Back-transformation of high-pressure phases in a shock melt vein of an H-chondrite during atmospheric passage: Implications for the survival of high-pressure phases after decompression
書誌事項
- 公開日
- 2004-01
- 権利情報
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- https://www.elsevier.com/tdm/userlicense/1.0/
- https://www.elsevier.com/legal/tdmrep-license
- DOI
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- 10.1016/s0012-821x(03)00585-5
- 公開者
- Elsevier BV
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説明
Abstract We investigated the H6-chondrite Yamato 75267, in which a fusion crust cuts a shock melt vein. The shock vein region, more than 280 μm from the fusion crust, contains high-pressure phases, such as ringwoodite, majorite-pyrope ss garnet and NaAlSi 3 O 8 hollandite. However, the shock vein close to the fusion crust entirely consists of the low-pressure polymorphs, olivine, low-Ca pyroxene and plagioclase glass. The boundary between low- and high-pressure phase regions is parallel to the fusion crust. During the atmospheric passage, the peripheral part of the chondrite was melted to form the fusion crust. Our microscopic, laser micro-Raman, electron microprobe investigations and calculations indicate an area up to 300 μm from the fusion crust experienced a temperature of 1400°C after 3 s during the melting of the peripheral part. The high-pressure phases would, at this conditions, quickly transform back to their low-pressure polymorphs. The result obtained here indicates that post-shock temperatures in the interior part of the veins were much lower than 1400°C, thus leading to the survival of high-pressure phases in heavily shocked chondrites.
収録刊行物
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- Earth and Planetary Science Letters
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Earth and Planetary Science Letters 217 (1-2), 141-150, 2004-01
Elsevier BV