Origin of a metamorphosed lithic clast in CM chondrite Grove Mountains 021536

• Published in: Meteoritics & Planetary Science
• Main Authors: Zhang, Aicheng, Guan, Yunbin, Hsu, Weibiao, Liu, Yang, Taylor, Lawrence A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Meteoritical Society 2010
• Subjects: Antarc*; Antarctic; Antarctica; Polar Research Institute of China
• Online Access: https://doi.org/10.1111/j.1945-5100.2010.01020.x

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 (Fs_(9.7–11.1)Wo_(48.3–51.6)), plagioclase (An_(43–46.5)), nepheline, merrillite, Al-rich chromite (21.8 wt% Al_2O_3; 4.43 wt% TiO_2), and pentlandite. Δ^(17)O 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. © 2010 The Meteoritical Society. Received 24 May 2009; revision accepted 26 October 2009. Published Online: 7 May 2010. The meteorite sample was graciously provided by the Polar Research Institute of China. We thank Allan Patchen for his kind assistance during electron probe analyses at the University of Tennessee. The authors would like to express their gratitude to Drs. Sasha Krot, Addi Bischoff, and Harold C. Connolly Jr. for their suggestions, comments, and helpful reviews and to the associate editor Dr. Cyrena Goodrich for her editorial efforts. The work was supported by National Science Foundation of China (Grants 40703015, 40773046), the Minor Planet Foundation of China, the Open Foundation of State Key Laboratory for Mineral Deposits Research, Nanjing University (Grant No. 14-8-6), and the Planetary Geosciences Institute at the University of Tennessee, ...