Origin of a metamorphosed lithic clast in CM chondrite Grove Mountains 021536 |
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| Authors: | Aicheng ZHANG Yunbin GUAN Weibiao HSU Yang LIU Lawrence A TAYLOR |
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| Institution: | 1. Laboratory for Astrochemistry and Planetary Science, Lunar and Planetary Science Center, Purple Mountain Observatory, Nanjing 210008, China;2. Department of Earth & Planetary Sciences, Planetary Geosciences Institute, University of Tennessee, Knoxville, Tennessee 37996, USA;3. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA;4. Faculty of Earth Science, China University of Geosciences, Wuhan 430074, China |
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| Abstract: | Abstract– A metamorphosed lithic clast was discovered in the CM chondrite Grove Mountains 021536, which was collected in the Antarctica by the Chinese Antarctic Research Exploration team. The lithic clast is composed mainly of Fe‐rich olivine (Fo62) with minor diopside (Fs9.7–11.1Wo48.3–51.6), plagioclase (An43–46.5), nepheline, merrillite, Al‐rich chromite (21.8 wt% Al2O3; 4.43 wt% TiO2), and pentlandite. Δ17O values of olivine in the lithic clast vary from ?3.9‰ to ?0.8‰. Mineral compositions and oxygen isotopic compositions of olivine suggest that the lithic clast has an exotic source different from the CM chondrite parent body. The clast could be derived from strong thermal metamorphism of pre‐existing chondrule that has experienced low‐temperature anhydrous alteration. The lithic clast is similar in mineral assemblage and chemistry to a few clasts observed in oxidized CV3 chondrites (Mokoia and Yamato‐86009) and might have been derived from the interior of the primitive CV asteroid. The apparent lack of hydration in the lithic clast indicates that the clast accreted into the CM chondrite after hydration of the CM components. |
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