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ID 21460
本文ファイル
著者
Kikuchi, M.
Horie, K.
Gauthier-Lafaye, F.
NDC
地球科学・地学・地質学
抄録(英)
The isotopic analyses of rare earth elements (REE), Pb and U in several kinds of minerals from the clay and black shale layers above the Bangombe natural reactor, Gabon, were performed using a sensitive high-resolution microprobe (SHRIMP) to investigate the migration and retardation processes of fission products released from the reactor. REE isotopic data of the secondary minerals found in clays and black shales show that most of fission products were effectively trapped in the clays and not distributed into the black shales over the clays, which reveals that the clays play an important role in preventing fission products from spreading. Zircon crystals in the clays heterogeneously contain high-U regions (up to 28.3 wt%) with normal U-235/U-238 ratios (=0.00725) and significant amounts of fissiogenic REE, which suggest the occurrence of significant chemical fractionation between REE and U during the dissolution of reactor uraninite and the recrystallization of secondary U minerals. The Pb data suggest that galena grains in the clays were also formed by the mixing of the two components during a recent alteration event, and that a significant amount of Pb was derived from 2.05-Ga-old original uraninite rather than reactor uraninite. The U-Pb systematics of zircon provide chronological information on the old igneous activity associated with the basement rock formation at 2.8 Ga and geochemical evidence of the incomplete mixing of independent Pb and U sources. This result is consistent with previous chronological results in this area.
掲載誌名
Geochimica et Cosmochimica Acta
71巻
19号
開始ページ
4716
終了ページ
4726
出版年月日
2007-10
出版者
Pergamon-Elsevier Science Ltd
ISSN
0016-7037
NCID
出版者DOI
言語
英語
NII資源タイプ
学術雑誌論文
広大資料タイプ
学術雑誌論文
DCMIタイプ
text
フォーマット
application/pdf
著者版フラグ
author
権利情報
Copyright(c) 2007 Pergamon-Elsevier Science Ltd
関連情報URL(IsVersionOf)
http://dx.doi.org/10.1016/j.gca.2007.07.016
部局名
理学研究科