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クロミタイト: 不思議なマントル構成岩
http://hdl.handle.net/2297/35951
http://hdl.handle.net/2297/35951f2b47a26-7bdc-4d6b-aa4f-278e09311809
| 名前 / ファイル | ライセンス | アクション |
|---|---|---|
SC-PR-ARAI-S-392.pdf (3.5 MB)
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| Item type | 学術雑誌論文 / Journal Article(1) | |||||
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| 公開日 | 2017-10-03 | |||||
| タイトル | ||||||
| タイトル | クロミタイト: 不思議なマントル構成岩 | |||||
| タイトル | ||||||
| タイトル | Chromitites: An Enigmatic Mantle Rock Type | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | jpn | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_6501 | |||||
| 資源タイプ | journal article | |||||
| 著者 |
荒井, 章司
× 荒井, 章司 |
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| 著者別表示 |
Arai, Shoji
× Arai, Shoji |
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| 書誌情報 |
地學雜誌 = Journal of geography 巻 119, 号 2, p. 392-410, 発行日 2010-01-01 |
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| ISSN | ||||||
| 収録物識別子タイプ | ISSN | |||||
| 収録物識別子 | 0022-135X | |||||
| NCID | ||||||
| 収録物識別子タイプ | NCID | |||||
| 収録物識別子 | AN00322536 | |||||
| DOI | ||||||
| 関連タイプ | isIdenticalTo | |||||
| 識別子タイプ | DOI | |||||
| 関連識別子 | 10.5026/jgeography.119.392 | |||||
| 出版者 | ||||||
| 出版者 | 東京地学協会 = Geographical Society | |||||
| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Various characteristics of podiform chromitites, an enigmatic mantle rock member, are reviewed in this article. Chromitites are composed of chromian spinel, with the general formula (Mg, Fe2+)(Cr, Al, Fe3+)2O4, and silicates (mainly olivine). The Fe3+ content is generally very low, being less than 0.1 to all trivalent cations, in mantle chromian spinels. The Mg/(Mg + Fe2+) ratio (= Mg#) changes inversely with the Cr/(Cr + Al) ratio (= Cr#), which increases with an increase of degree of partial melting of mantle peridotites. The Cr# of chromian spinel is generally higher than 0.4 (generally 0.6 to 0.8) in podiform chromitites, varying widely from 0.1 to 0.9 in the mantle peridotite. The podiform chromitite forms pod-like bodies (dimensions of up to 1.5 km × 150 m for an individual pod) with a dunite envelope, totally set within mantle harzburgite. In well-preserved ophiolites, they occur in the uppermost mantle, especially in and beneath the Moho transition zone, which is dominated by dunite. The Cr# of chromian spinel is relatively low (0.4 to 0.6) around the Moho transition zone, and high (>0.6) at deeper levels in the mantle section. Chromitites are denser and less anisotropic in Vp than peridotites, and the Vp is 8.5 to 9 km/sec depending on the proportion of chromian spinel, and higher in the former than in the latter. The podiform chromitite has been interpreted to be one of melt/rock interaction products within the uppermost mantle harzburgite; hybridization of relatively Si-rich melt formed by the breakdown of orthopyroxenes of the wall harzburgite and subsequently supplied primitive melt cause oversaturation in chromian spinel, giving rise to formation of chromitite with a dunite envelope. The fractionated melt leaving high-Cr# podiform chromitite is possibly of arc-magma affinity. Chromitites with low-Cr# (0.4 to 0.6) chromian spinel can be in equilibrium with MORB. Recently found ultra-high pressure minerals, such as diamond, moissanite, Fe-silicides and Ni-Fe-Cr-C alloys, within chromian spinel of podiform chromitites make the genetical history of chromitites highly enigmatic. A new story, which incorporates the genesis and involvement of these highly reducing, ultra-high pressure minerals, is required. | |||||
| 権利 | ||||||
| 権利情報 | Copyright © 東京地学協会 Geographical Society | 許可を得て登録 | |||||
| 著者版フラグ | ||||||
| 出版タイプ | VoR | |||||
| 出版タイプResource | http://purl.org/coar/version/c_970fb48d4fbd8a85 | |||||
| 関連URI | ||||||
| 識別子タイプ | URI | |||||
| 関連識別子 | http://www.geog.or.jp/journal/ja/information-ja/about-this-journal-ja.html | |||||
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| 識別子タイプ | URI | |||||
| 関連識別子 | http://www.geog.or.jp/ | |||||
| 関連URI | ||||||
| 識別子タイプ | URI | |||||
| 関連識別子 | https://www.jstage.jst.go.jp/browse/jgeography/-char/ja/ | |||||
