Heterogeneous nature of the carbonaceous chondrite breccia Aguas Zarcas Cosmochemical characterization and origin of new carbonaceous chondrite lithologies
Heterogeneous nature of the carbonaceous chondrite breccia Aguas Zarcas Cosmochemical characterization and origin of new carbonaceous chondrite lithologies
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碳质球粒陨石角砾岩 Aguas Zarcas 的非均质性质 新碳质球粒陨石岩性的宇宙化学特征和起源
DOI：
10.1016/j.gca.2022.07.010
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发表时间：
2022
影响因子：
5
通讯作者：
Takahashi Yoshio et al.
中科院分区：
文献类型：
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作者：
Kerraouch Imene;Kebukawa Yoko;Bischoff Addi;Zolensky Michael E.;Wolfer Elias;Hellmann Jan L.;Ito Motoo;King Ashley;Trieloff Mario;Takahashi Yoshio et al.
2019年4月23日，哥斯达黎加发生了阿瓜斯扎卡斯陨石坠落事件。因为这块陨石很快就被发现了，它含有没有被地球过程污染的有价值的外星物质。我们的x射线计算机断层扫描（XCT）和扫描电子显微镜（SEM）对早期工作的各种雨前碎片（Kerraouch等人，2020;2021）的结果显示了几种不同的岩性：两种不同的富金属岩性（Met-1和Met-2）， ccm /2岩性，C1岩性和角化CM2岩性，由不同的岩石学类型组成。在这里，我们进一步研究了角砾岩Aguas Zarcas陨石的这些岩性，并报告了新的详细矿物学，化学，同位素和有机质特征。除了岩石学上的差异外，岩性也显示出不同的化学和同位素组成。它们的体积氧同位素组成的变化表明，不同的岩性形成于不同的环境和/或不同的条件下（如水/岩比）。每种岩性在演化过程中都经历了不同的水化时期。总之，这表明可能有多个前体母体参与了这些冲击角化、混合和重新组合的过程。CM -1 /2和Met-1岩性的Cr和Ti同位素数据与其他CM球粒陨石的数据一致，尽管Met-1的ε50Ti同位素组成明显较低，这可能是由于样品在大块陨石尺度上的非均质性，并且可能反映了Aguas Zarcas不同岩性中耐火相的丰度变化。最后，对各种岩性的有机物的检查也表明没有热事件的有力证据，但不能完全排除短期加热。拉曼参数表明，其峰值温度低于Yamato-793321 （CM2, ~ 400°C）。考虑到这项研究提供的新信息，我们现在可以更好地了解Aguas Zarcas子体的起源和形成历史。
On April 23rd, 2019, the Aguas Zarcas meteorite fall occurred in Costa Rica. Because the meteorite was quickly recovered, it contains valuable extraterrestrial materials that have not been contaminated by terrestrial processes. Our X-ray computed tomography (XCT) and scanning electron microscopy (SEM) results on various pre-rain fragments from earlier work (Kerraouch et al., 2020; 2021) revealed several distinct lithologies: Two distinct metal-rich lithologies (Met-1 and Met-2), a CM1/2 lithology, a C1 lithology, and a brecciated CM2 lithology consisting of different petrologic types. Here, we further examined these lithologies in the brecciated Aguas Zarcas meteorite and report new detailed mineralogical, chemical, isotopic, and organic matter characteristics. In addition to petrographic differences, the lithologies also display different chemical and isotopic compositions. The variations in their bulk oxygen isotopic compositions indicate that the various lithologies formed in different environments and/or under diverse conditions (e.g., water/rock ratios). Each lithology experienced a different hydration period during its evolution. Together, this suggests that multiple precursor parent bodies may have been involved in these processes of impact brecciation, mixing, and re-assembly. The Cr and Ti isotopic data for both the CM1/2 and Met-1 lithology are consistent with those of other CM chondrites, even though Met-1 displays a significantly lower ε50Ti isotopic composition that may be attributable to sample heterogeneities on the bulk meteorite scale and may reflect variable abundances of refractory phases in the different lithologies of Aguas Zarcas. Finally, examination of the organic matter of the various lithologies also suggests no strong evidence of thermal events, but a short-term heating cannot completely be excluded. Raman parameters indicate that the peak temperature has been lower than that for Yamato-793321 (CM2, ∼400 °C). Considering the new information presented in this study, we now better understand the origin and formation history of the Aguas Zarcas daughter body.