WEKO3
アイテム
Noble gas and oxygen isotope studies of aubrites: A clue to origin and histories
http://hdl.handle.net/2261/21023
http://hdl.handle.net/2261/210236cd9d125-ecb7-4e5e-a2d4-53cab5b0e67e
| 名前 / ファイル | ライセンス | アクション |
|---|---|---|
GCA07_71_251_corr.pdf (499.5 kB)
|
|
| Item type | 学術雑誌論文 / Journal Article(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2008-11-05 | |||||
| タイトル | ||||||
| タイトル | Noble gas and oxygen isotope studies of aubrites: A clue to origin and histories | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源 | http://purl.org/coar/resource_type/c_6501 | |||||
| タイプ | journal article | |||||
| 著者 |
Miura, Yayoi N.
× Miura, Yayoi N.× Hidaka, Hiroshi× Nishiizumi, Kunihiko× Kusakabe, Minoru |
|||||
| 著者所属 | ||||||
| 著者所属 | Earthquake Research Institute, University of Tokyo | |||||
| 著者所属 | ||||||
| 著者所属 | Department of Earth and Planetary Systems Science, Hiroshima University | |||||
| 著者所属 | ||||||
| 著者所属 | Space Science Laboratory, University of California, Barkeley | |||||
| 著者所属 | ||||||
| 著者所属 | Institute for Study of the Earth’s Interior, Okayama University | |||||
| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Noble gas measurements were performed for nine aubrites: Bishopville, Cumberland Falls, Mayo Belwa, Mount Egerton, Norton County, Peña Blanca Spring, Shallowater, ALHA 78113 and LAP 02233. These data clarify the origins and histories, particularly cosmic-ray exposure and regolith histories, of the aubrites and their parent body(ies). Accurate cosmic-ray exposure ages were obtained using the 81Kr–Kr method for three meteorites: 52 ± 3, 49 ± 10 and 117 ± 14 Ma for Bishopville, Cumberland Falls and Mayo Belwa, respectively. Mayo Belwa shows the longest cosmic-ray exposure age determined by the 81Kr–Kr method so far, close to the age of 121 Ma for Norton County. These are the longest ages among stony meteorites. Distribution of cosmic-ray exposure ages of aubrites implies 4–9 break-up events (except anomalous aubrites) on the parent body. Six aubrites show “exposure at the surface” on their parent body(ies): (i) neutron capture 36Ar, 80Kr, 82Kr and/or 128Xe probably produced on the respective parent body (Bishopville, Cumberland Falls, Mayo Belwa, Peña Blanca Spring, Shallowater and ALHA 78113); and/or (ii) chondritic trapped noble gases, which were likely released from chondritic inclusions preserved in the aubrite hosts (Cumberland Falls, Peña Blanca Spring and ALHA 78113). The concentrations of 128Xe from neutron capture on 127I vary among four measured specimens of Cumberland Falls (0.5–76 × 10−14 cm3STP/g), but are correlated with those of radiogenic 129Xe, implying that the concentrations of (128Xe)n and (129Xe)rad reflect variable abundances of iodine among specimens. The ratios of (128Xe)n/(129Xe)rad obtained in this work are different for Mayo Belwa (0.045), Cumberland Falls (0.015) and Shallowater (0.001), meaning that neutron fluences, radiogenic 129Xe retention ages, or both, are different among these aubrites. Shallowater contains abundant trapped Ar, Kr and Xe (2.2 × 10−7, 9.4 × 10−10 and 2.8 × 10−10 cm3STP/g, respectively) as reported previously (Busemann and Eugster, 2002). Isotopic compositions of Kr and Xe in Shallowater are consistent with those of Q (a primordial noble gas component trapped in chondrites). The Ar/Kr/Xe compositions are somewhat fractionated from Q, favoring lighter elements. Because of the unbrecciated nature of Shallowater, Q-like noble gases are considered to be primordial in origin. Fission Xe is found in Cumberland Falls, Mayo Belwa, Peña Blanca Spring, ALHA 78113 and LAP 02233. The majority of fission Xe is most likely 244Pu-derived, and about 10–20% seems to be 238U-derived at 136Xe. The observed (136Xe)Pu corresponds to 0.019–0.16 ppb of 244Pu, from which the 244Pu/U ratios are calculated as 0.002–0.009. These ratios resemble those of chondrites and other achondrites like eucrites, suggesting that no thermal resetting of the Pu–Xe system occurred after 4.5 Ga ago. We also determined oxygen isotopic compositions for four aubrites with chondritic noble gases and a new aubrite LAP 02233. In spite of their chondritic noble gas signatures, oxygen with chondritic isotopic compositions was found only in a specimen of Cumberland Falls (Δ17O of 0.3‰). The other four aubrites and the other two measured specimens of Cumberland Falls are concurrent with the typical range for aubrites. | |||||
| 書誌情報 |
Geochimica et cosmochimica acta 巻 71, 号 1, p. 251-270, 発行日 2007-01-01 |
|||||
| ISSN | ||||||
| 収録物識別子タイプ | ISSN | |||||
| 収録物識別子 | 00167037 | |||||
| 書誌レコードID | ||||||
| 収録物識別子タイプ | NCID | |||||
| 収録物識別子 | AA00655038 | |||||
| DOI | ||||||
| 識別子タイプ | DOI | |||||
| 関連識別子 | info:doi/10.1016/j.gca.2006.07.040 | |||||
| 権利 | ||||||
| 権利情報 | Copyright c 2008 Elsevier Ltd. All rights reserved | |||||
| フォーマット | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | application/pdf | |||||
| 著者版フラグ | ||||||
| 値 | author | |||||
| 日本十進分類法 | ||||||
| 主題Scheme | NDC | |||||
| 主題 | 453 | |||||
| 出版者 | ||||||
| 出版者 | Elsevier | |||||
| 関係URI | ||||||
| 識別子タイプ | URI | |||||
| 関連識別子 | http://www.elsevier.com/wps/find/journaldescription.cws_home/212/description#description | |||||
