Water-susceptible primordial noble gas components in less-altered CR chondrites: A possible link to cometary materials
Water-susceptible primordial noble gas components in less-altered CR chondrites: A possible link to cometary materials
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变化较小的 CR 球粒陨石中易受水影响的原始惰性气体成分：与彗星材料的可能联系
DOI：
10.1016/j.gca.2021.08.012
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发表时间：
2021
影响因子：
5
通讯作者：
Nakamura Tomoki
中科院分区：
文献类型：
--
作者：
Obase Tomoya;Nakashima Daisuke;Choi Jisu;Enokido Yuma;Matsumoto Megumi;Nakamura Tomoki
我们报告了Renazzo型（CR）玄武岩EET 92048，MIL 090657，NWA 801和水热处理的MIL 090657样品的岩石学，矿物学和惰性气体特征的详细表征，以研究含水较少蚀变的CR玄武岩中由水敏感性材料承载的原始惰性气体。惰性气体的提取采用分步加热法。对MIL 090657的水热处理导致基质中的无定形硅酸盐的改变和在低温下从未处理的样品中释放的大量He和Ne的去除。EET 92048和MIL 090657中的36 Ar/132 Ar比值比Q惰性气体成分高5倍，尽管这两颗陨石都没有显示出任何太阳风惰性气体的证据。分析结果表明，含水较少改变的CR辉长岩包含两个不同的原始惰性气体组分托管的水敏感性材料：一个同位素类Q的富Ne组分和富Ar组分。类Q富Ne组分的特征与彗星物质中的类Q富Ne组分的特征一致。我们认为CR球粒陨石形成于更大的日心距离处，并且与彗星具有类似的含有类Q富Ne成分的物质。富Ar组分在CR球粒陨石、普通球粒陨石和其他无水碳质球粒陨石中的存在，提供了富Ar载体在普通球粒陨石和碳质球粒陨石形成区中的全球分布的证据。
We report detailed characterizations of the petrology, mineralogy, and noble gas signatures of Renazzo-type (CR) chondrites EET 92048, MIL 090657, NWA 801, and hydrothermally treated MIL 090657 samples to investigate primordial noble gases hosted by water-susceptible materials in aqueously less-altered CR chondrites. The noble gases were extracted by a stepwise heating method. The hydrothermal treatment on MIL 090657 resulted in the alteration of amorphous silicates in the matrix and the removal of large amounts of He and Ne that were released at low temperature from the untreated sample. The36Ar/132Xe ratios in EET 92048 and MIL 090657 are ~5 times higher than that of the Q noble gas component, although both meteorites do not show any evidence for solar wind noble gases. The analyses revealed that aqueously less-altered CR chondrites contain two distinct primordial noble gas components hosted by water-susceptible materials: an isotopically Q-like Ne-rich component and an Ar-rich component. The characteristics of the Q-like Ne-rich component are consistent with those of Q-like Ne in cometary materials. We propose that the CR chondrites formed at a greater heliocentric distance and share similar materials hosting the Q-like Ne-rich component with comets. The presence of the Ar-rich component in the CR chondrites, as well as in ordinary chondrites and other anhydrous carbonaceous chondrites, provides evidence of the global distribution of the Ar-rich carriers in the ordinary and carbonaceous chondrite forming regions.