| Project/Area Number |
61540593
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
鉱物学(含岩石・鉱床学)
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
SATO Hiroaki Fac. Integ. Arts & Sci., Hiroshima Univ. Assoc. Prof., 総合科学部, 助教授 (60019495)
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| Project Period (FY) |
1986 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1988: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1987: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1986: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | High-magnesian andesite / Boninite / Sanukitoid / Sr-Nd isotopic ratios / Trace element composition / Element partitioning / Oxygen fugacity meter / 火山岩石基組織 / 元素配分 / 斜長石 / 酸素フェガシティ計 / 結晶核密度 / 高マグネシア安山岩類 / マグマ生成条件 / 元素分配 / 酸素分圧 / サヌカイト / 生成環境 / 初生安山岩 / 斜方輝石 / マグマ混合 |
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| Research Abstract |
Gelogical, petrographical and chemical studies were carried out on high-magnesian andesites of northeast Shikoku, Noto Peninsula, and northwest Kyushu, and boninite of Ogasawara Islands. High-magnesian andesite (sanukitoid) of northeast Shikoku may repesent primary andesite derived from hydrated mantle peridotite, though the source area may be aeverely affected by subducted sediments. Bronzite andesites of Noto Peninsula and NW Kyushu were probably formed by mixing of primitive basalt and dacite or rhyolite magmas. Trace element composition of boninite of Ogasawara Islands is characterized by low HFSE and rather high alkali contents with intermediate alkali earths. Such enrichement (e.g. high Rb/Ba and Ba/La ratios) is common among the high-magnesian andesites presently investigated, and is diagnostic from island arc tholeiites.
1-atmosphere melting studies of some volcanic rocks afforded a new oxygen fugacity meter. It uses Mg-Fe partition relationship between plagioclase and magma. The oxygen fugacity meter is sensitive at ca. log fo_2=-6 - -11, and may have wide applicability to plagioclase-phyric volcanics.
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