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A shock‐produced (Mg, Fe)SiO 3 glass in the Suizhou meteorite
Author(s) -
CHEN Ming,
XIE Xiande,
GORESY Ahmed EL
Publication year - 2004
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2004.tb00076.x
Subject(s) - troilite , pyroxene , ringwoodite , meteorite , shock metamorphism , chondrite , mineralogy , geology , olivine , perovskite (structure) , materials science , chemistry , crystallography , astrobiology , physics
— Ovoid grains consisting of glass of stoichiometric (Mg, Fe)SiO 3 composition that is intimately associated with majorite were identified in the shock veins of the Suizhou meteorite. The glass is surrounded by a thick rim of polycrystalline majorite and is identical in composition to the parental low‐Ca pyroxene and majorite. These ovoid grains are surrounded by a fine‐grained matrix composed of majorite‐pyrope garnet, ringwoodite, magnesiowüstite, metal, and troilite. This study strongly suggests that some precursor pyroxene grains inside the shock veins were transformed to perovskite within the pyroxene due to a relatively low temperature, while at the rim region pyroxene grains transformed to majorite due to a higher temperature. After pressure release, perovskite vitrified at post‐shock temperature. The existence of vitrified perovskite indicates that the peak pressure in the shock veins exceeds 23 GPa. The post‐shock temperature in the meteorite could have been above 477 °C. This study indicates that the occurrence of high‐pressure minerals in the shock veins could not be used as a ubiquitous criterion for evaluating the shock stage of meteorites.