Abstract Here we present the abundances and isotopic compositions of the noble gases He, Ne, Ar, Kr, and Xe in five bulk ordinary chondrites from Antarctica, namely Grove Mountains (GRV)054472, GRV053690, GRV022403, GRV023149, and GRV052243. The cosmic ray exposure (CRE) ages of the three H chondrites GRV054472 (H3), GRV053690 (H4), and GRV022403 (H4) are 3.8 ​± ​0.3 ​Ma, 5.9 ​± ​0.4 ​Ma, and 16.6 ​± ​1.5 ​Ma, respectively. This finding is consistent with peaks in the exposure age histogram for H chondrites at 4 ​Ma and 7.2 ​Ma, respectively and also with the broad age cluster at 15–20 ​Ma, which is especially pronounced for H4 chondrites. The two L6 chondrites GRV023149 and GRV052243 are most likely paired with consistent exposure ages of 17.4 ​± ​1.1 ​Ma and 17.6 ​± ​1.5 ​Ma that both fall into the peak at 15 ​Ma for L6 chondrites. The two meteorites GRV054472 and GRV053690 show significant 3He or 3H diffusive losses of about 10% and 20–30%, respectively. The 4He gas retention ages for the three H chondrites are in the range 1.09–3.18 ​Ga, showing different degrees of degassing either at a thermal event on the parent body or during cosmic ray exposure after the ejection from the parent body. The low gas retention ages for the two L6 chondrites based on (U–Th)/He systematics are 259 ​Ma (mean age of two aliquots) and 320 ​Ma or 364 ​Ma (mean age of two aliquots) and 307 ​Ma based on K–Ar system. These ages indicate significant gas loss during the catastrophic break-up of the L-chondrite parent body. Trapped Kr in GRV054472 and GRV053690-2 is almost pure Kr-Q. In addition, other meteorites also contain Q as trapped Kr, but have discernable cosmogenic Kr. The excess 82Kr observed in GRV052243 and GRV022403 is due to the neutron capture on 81Br. Radiogenic 129Xe∗ from the decay of 129I was observed in all studied chondrites. Measured Xe isotopes in all the studied chondrites predominantly shows Q component with minor contributions from the terrestrial atmosphere. For the samples GRV053690-2 and GRV023149-2, measured Xe falls on a mixing line with Xe-SW and Xe-HL, although the later component contributes very little.

中文翻译：

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来自南极洲格罗夫山脉的五种普通球粒陨石中的惰性气体

摘要 在这里，我们介绍了来自南极洲的五种普通球粒陨石，即格罗夫山脉 (GRV)054472、GRV053690、GRV022403、GRV023149 和 GRV052243 中稀有气体 He、Ne、Ar、Kr 和 Xe 的丰度和同位素组成。三个H球粒陨石GRV054472（H3）、GRV053690（H4）和GRV022403（H4）的宇宙射线暴露（CRE）年龄分别为3.8±0.3Ma、5.9±0.4±6Ma和16。分别为 1.5 毫安。这一发现与 H 球粒陨石分别在 4 Ma 和 7.2 Ma 的暴露年龄直方图中的峰值一致，也与 15-20 Ma 的广泛年龄簇一致，这对于 H4 球粒陨石尤其明显。两个 L6 球粒陨石 GRV023149 和 GRV052243 最有可能与 17.4 ± 1.1 Ma 和 17.6 ± 1.5 Ma 的一致暴露年龄配对，它们都落入 L6 球粒陨石的 15 Ma 峰值。两颗陨石 GRV054472 和 GRV053690 显示出显着的 3He 或 3H 扩散损失，分别约为 10% 和 20-30%。三个 H 球粒陨石的 4He 气体保留年龄在 1.09-3.18 Ga 的范围内，在母体上的热事件或从母体喷射后的宇宙射线暴露期间显示出不同程度的脱气。基于 (U–Th)/He 系统学的两个 L6 球粒陨石的低气体保留年龄为 259 Ma（两等分试样的平均年龄）和 320 Ma 或 364 Ma（两等分试样的平均年龄）和 307 Ma基于 K-Ar 系统。这些年龄表明在 L 球粒陨石母体的灾难性破裂过程中发生了大量的气体损失。GRV054472 和 GRV053690-2 中捕获的 Kr 几乎是纯 Kr-Q。此外，其他陨石也含有 Q 作为捕获的 Kr，但具有可辨别的宇宙源 Kr。在 GRV052243 和 GRV022403 中观察到的过量 82Kr 是由于 81Br 上的中子俘获。在所有研究的球粒陨石中都观察到了来自 129I 衰变的放射性 129Xe*。在所有研究的球粒陨石中测量的 Xe 同位素主要显示 Q 分量，而来自陆地大气的贡献很小。对于样品 GRV053690-2 和 GRV023149-2，测量的 Xe 落在与 Xe-SW 和 Xe-HL 的混合线上，尽管后者的贡献很小。