Regolith history of the aubritic meteorite parent body revealed by neutron capture effects on Sm and Gd isotopes

Geochimica et Cosmochimica Acta 70 巻 13 号 3449-3456 頁 2006-07 発行
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タイトル ( eng )
Regolith history of the aubritic meteorite parent body revealed by neutron capture effects on Sm and Gd isotopes
作成者
Yoneda Shigekazu
Marti Kurt
収録物名
Geochimica et Cosmochimica Acta
70
13
開始ページ 3449
終了ページ 3456
抄録
Enstatite achondrites (aubrites) when compared to other stone meteorites have unusually long cosmic-ray exposure (CRE) ages. We report here the 150Sm/149Sm and 158Gd/157Gd ratios in six different structural phases, i.e., light and dark (shocked) grains and in matrix materials of Pesyanoe, in three different fragments from Pena Blanca Spring, and in one from Norton County, Shallowater, and Khor Temiki, to investigate the regolith history on the aubrite parent body. The results from phases components of Pesyanoe confirm earlier reported evidence for regolith irradiation of several aubrites. The inferred neutron fluences for six Pesyanoe separates vary between (2.13 and 2.82) × 1016 n cm-2. The fluences also significantly exceed those expected from cosmic-ray irradiation during transit to Earth and approach those observed in the lunar regolith. These observations confirm that the brecciated Pesyanoe meteorite, which contains solar wind (SW) gases only in dark phases, was processed in a regolith and that structural phases were differentially irradiated before compaction. On the other hand, in some aubrites (Mt. Egerton, Shallowater, Pena Blanca Spring, Norton County) neutron capture effects may entirely be due to space irradiation.
NDC分類
天文学・宇宙科学 [ 440 ]
言語
英語
資源タイプ 学術雑誌論文
出版者
Elsevier Inc.
発行日 2006-07
権利情報
Copyright (c) 2006 Elsevier Inc.
出版タイプ Author’s Original(十分な品質であるとして、著者から正式な査読に提出される版)
アクセス権 オープンアクセス
収録物識別子
[ISSN] 0016-7037
[DOI] 10.1016/j.gca.2006.04.009
[NCID] AA00655038
[DOI] http://dx.doi.org/10.1016/j.gca.2006.04.009 ~の異版である