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Unique igneous textures and shock metamorphism of the Northwest Africa 7203 angrite: Implications for crystallization processes and the evolutionary history of the angrite parent body

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Title
Unique igneous textures and shock metamorphism of the Northwest Africa 7203 angrite: Implications for crystallization processes and the evolutionary history of the angrite parent body
Other Titles
앵그라이트 NWA 7203의 화성 기원 조직과 충격 변성 특성 연구
Authors
Hayashi, Hideyuki
Mikouchi, Takashi
Kim, Nak Kyu
Park, Changkun
Sano, Yuji
Takenouchi, Atsushi
Yamaguchi, Akira
Kagi, Hiroyuki
Bizzarro, Martin
Subject
Geochemistry & Geophysics
Keywords
MARTIAN METEORITEPETROLOGYSAHARA-99555MINERALOGYDORBIGNYORIGINAGES
Issue Date
2022-01
Citation
Hayashi, Hideyuki, et al. 2022. "Unique igneous textures and shock metamorphism of the Northwest Africa 7203 angrite: Implications for crystallization processes and the evolutionary history of the angrite parent body". METEORITICS & PLANETARY SCIENCE, 57(1): 105-121.
Abstract
Northwest Africa (NWA) 7203 is a quenched angrite, showing mineralogical features typically not present in other quenched angrites. NWA 7203 exhibits textures whose grain size varies from fine grains (<10 mu m) to coarse grains (similar to 3 mm), while other quenched angrites show only single-sized textures. Fine-grained and coarse-grained lithologies have nearly the same bulk compositions. Cooling rates were estimated to be similar to 80 degrees C h(-1) for fine-grained lithologies and similar to 1 degrees C h(-1) for coarse-grained lithologies. Mg-rich olivines (similar to Fo(64)) were found only in fine-grained lithologies. Crystallization of NWA 7203 started in the fine-grained lithologies with Mg-rich olivine grains acting as seeds for crystallization. Coarse-grained lithologies were subsequently formed under conditions of slower cooling. NWA 7203 shows clear shock metamorphic textures unlike other quenched angrites except for NWA 1670. We confirm that the oxygen isotopic ratios of NWA 7203 plot on the angrite fractionation line within uncertainty. However, the obtained Pb-Pb age of NWA 7203 is 4543 +/- 19 Ma, younger than the ages of other quenched angrites, which might be a result of disturbance by shock metamorphism. The finding of shock metamorphism of NWA 7203 suggests that some angrites might be derived from asteroids that remained large (>10 km in diameter) during the late heavy bombardment.
URI
https://repository.kopri.re.kr/handle/201206/13263
DOI
http://dx.doi.org/10.1111/maps.13776
Type
Article
Station
기타(산소동위원소질량분석기)
Indexed
SCIE
Appears in Collections  
2021-2021, Mantle dynamics and tectonic evolutions of Zealandia-Antarctic domain (21-21) / Park, Sung Hyun (PE21050)
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