Petrology, mineralogy, porosity, and cosmic-ray exposure history of Huaxi ordinary chondrite

1Shijie Li, 2Shijie Wang, 3Ingo Leya, 1Yang Li, 1Xiongyao Li, 3Thomas Smith
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.12842]
1Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
2State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
3Physikalisches Institut, Universität Bern, Switzerland
Published by arrangement with John Wiley&Sons

A meteorite fall was heard and collected on July 13, 2010 at about 18:00 (local time) in the Shibanjing village of the Huaxi district of Guiyang, Guizhou province, China. The total mass of the fall is estimated to be at least 1.6 kg; some fragments are missing. The meteorite consists mainly of olivine, low-Ca pyroxene, high-Ca pyroxene, plagioclase, kamacite, taenite, and troilite. Minor phases include chromite and apatite. Various textural types of chondrules exist in this meteorite: most chondrule textures can be easily defined. The grain sizes of secondary plagioclase in this meteorite range from 2 to 50 μm. The chemical composition of olivine and low-Ca pyroxene are uniform; Fa in olivine and Fs in low-Ca pyroxene are, respectively, 19.6 ± 0.2 and 17.0 ± 0.3 (mole%). Huaxi has been classified as an H5 ordinary chondrite, with a shock grade S2, and weathering W0. The weak shock features, rare fractures, and the high porosity (17.6%) indicates that Huaxi is a less compacted meteorite. The preatmospheric radius of Huaxi is ~11 cm, corresponding to ~21 kg. The meteorite experienced a relatively short cosmic-ray exposure of about 1.6 ± 0.1 Ma. The 4He and 40Ar retention ages are older than 4.6 Ga implying that Huaxi did not degas after thermal metamorphism on its parent body.

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