Item type |
紀要論文(ELS) / Departmental Bulletin Paper(1) |
公開日 |
1991-03-01 |
タイトル |
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タイトル |
Petrological and geochemical study of the Yamato-74359 and Yamato-74360 achondrites |
言語 |
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言語 |
eng |
資源タイプ |
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資源タイプ識別子 |
http://purl.org/coar/resource_type/c_6501 |
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資源タイプ |
departmental bulletin paper |
ID登録 |
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ID登録 |
10.15094/00004541 |
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ID登録タイプ |
JaLC |
ページ属性 |
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内容記述タイプ |
Other |
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内容記述 |
P(論文) |
著者名(英) |
Ikeda, Yukio
Tsuchiyama, Akira
Ebihara, Mitsuru
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著者所属(英) |
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en |
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Department of Earth Sciences, Faculty of Science, Ibaraki University |
著者所属(英) |
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en |
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Department of Culture, Osaka University |
著者所属(英) |
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en |
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Department of Chemistry, Tokyo Metropolitan University |
抄録(英) |
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内容記述タイプ |
Other |
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内容記述 |
Two Antarctic achondrites, Yamato (Y)-74359 and Y-74360,are very similar in bulk chemical compositions to the silicate portions of H chondrites, but the siderophile elements are extremely depleted in comparison to those of H chondrites. They consist of olivine, pyroxene and cryptocrystalline feldspar with minor amounts of chromite, kamacite, and troilite, and the chemical compositions of the constituent minerals are similar to those in H chondrites. Taking into consideration that the two achondrites have oxygen isotopic compositions typical of H chondrites, they were produced from H chondrites or the precursors of H chondrites. Chondrules are not observed, and the texture of the two achondrites is similar to one another, although Y-74360 is coarser-grained than Y-74359. Olivine occurs as euhedral or subhedral grains, mostly smaller than 100 microns in diameter, and they show slight chemical zoning, from magnesian cores (Fo_<82-83>) to ferroan rims (Fo_<80-78>). Orthopyroxene occurs as euhedral grains, larger than olivine grains, and also shows slight chemical zoning, from Ca-poorer magnesian cores to Ca-richer ferroan rims. Clinopyroxene occurs as rims of orthopyroxenes and shows remarkable chemical zoning continuously from pigeonitic interiors to augitic rims. Cryptocrystalline feldspar occurs in interstitial spaces between olivine and/or pyroxene, and seems to have crystallized in interstitial liquids in a rapid cooling condition. The cryptocrystalline feldspars in Y-74359 are chemically heterogeneous, classified into three groups, albite (An_<1-4>Ab_<94-96>Or_<2-4>), anorthoclase (An_<6-10>Ab_<79-86>Or_<4-15>), and intermediate alkali feldspar (An_<1-2>Ab_<51-56>Or_<42-47>), and occur in different portions of the thin section. The two achondrites seem to have formed by partial melting from heterogeneous silicate precursors of unequilibrated H chondrites. |
雑誌書誌ID |
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収録物識別子タイプ |
NCID |
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収録物識別子 |
AA10784627 |
書誌情報 |
Proceedings of the NIPR Symposium on Antarctic Meteorites
巻 4,
p. 131-143,
発行日 1991-03
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出版者 |
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出版者 |
National Institute of Polar Research |