Shidian meteorite, a new fall analog of near‐Earth asteroid (101955) Bennu

作者：Yan Fan, Shijie Li, Shen Liu, Qing‐Zhu Yin, Guangming Song, Rui Xu, Jiang Zhang, Pengfei Zhang, Chengyu Liu, Rong Wang, Thomas Smith · 发表于：Meteoritics and Planetary Science · 年份：2022 · DOI：10.1111/maps.13925 · 被引用次数：9 · 研究领域：Astro and Planetary Science、Planetary Science and Exploration、Geological and Geochemical Analysis

Abstract Shidian is a recent meteorite which fell in Yunnan province, China, on November 27, 2017, and has been classified as a CM2 chondrite. Petrography, mineralogy, oxygen and chromium isotopic composition, reflectance spectrum, and density studies of Shidian are reported in this study. Clasts with different aqueous alteration degree, two type 1 clasts with nontypical CM petrography, and one metamorphic clast are observed in Shidian. Mineralogically, Shidian main body consists of phyllosilicates (∼70 vol%), forsterite (∼13 vol%), fayalitic olivine, carbonates, sulfide, high‐Ca pyroxene, magnetite framboids, and Fe‐Ni metal. The average electron microprobe analysis (EMPA) analytical totals of phyllosilicates are 84.07 ± 1.75 wt%, with average FeO/SiO 2 of tochilinite–cronstedtite intergrowths (TCIs) in different clasts ranging from 1.18 to 3.29. The bulk geochemical composition is characterized by flat rare earth element pattern, and by depletion of highly volatile elements. The whole rock oxygen isotopic composition is −0.51 ± 0.73‰, 5.44 ± 1.01‰, and −3.38 ± 0.20‰ for δ 17 O, δ 18 O, and Δ 17 O, respectively, with bulk chromium isotopic composition as ε 54 Cr = 1.00 ± 0.11. The grain density, bulk density, and porosity are 2.758 ± 0.008 g cm −3 , 2.500 ± 0.004 g cm −3 , and 9.37 ± 0.59%, respectively. The reflectance spectrum shows “blue” (negative) continuum slope across the visible and near‐infrared range, with characteristic absorption features (such as 0.765, 0.923, a...