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Exposure history, petrology, and shock‐induced sulfidization reaction of Alatage Mountain 001 strewn field samples
Author(s) -
Li Shijie,
Leya Ingo,
Wang Shijie,
Smith Thomas,
Bao Huiming,
Fan Yan,
Mo Bing
Publication year - 2021
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/maps.13710
Subject(s) - troilite , meteorite , geology , chondrite , petrography , geochemistry , pyroxene , parent body , olivine , mineralogy , partial melting , iron meteorite , basalt , astrobiology , physics
Several hundred meteorites with a total mass of over 100 kg were collected as the Alatage Mountain (AM) strewn field located in the Kumtag desert, Xinjiang Province, China. Twelve AM meteorites were studied in this work. Petrography, mineralogy, bulk chemistry, bulk oxygen isotopic compositions, and light noble gas concentrations and isotopic compositions were determined for all or for a selection of the meteorites. The studied meteorites are L‐chondrites that suffered a very strong impact; impact melt veins and melt pockets are widely distributed. More than 50% of the troilite exists in the form of blebs and veins in olivine and pyroxene. Some of these meteorites are impact melt recrystallized rocks (e.g., AM 037). The strong impact caused the decomposition of troilite, which led in AM 034 to the sulfidization reaction of olivine. The metal in most meteorites is almost completely altered, and the troilite has been significantly oxidized. Weathering resulted in the depletion of Mg, Fe, Co, and Ni, and the enrichment of Sr, Ba, Pb, and U in these meteorites. The cosmic ray exposure (CRE) ages measured for these specimens range between 6.2 ± 1.9 Ma and 9.0 ± 2.7 Ma, depending on the cosmogenic nuclide used. The average CRE age is 7.6 ± 1.3 Ma. Both 4 He and 40 Ar gas retention ages indicate that the strong impact which caused the shock effects occurred about 320 Ma ago.