Genetic Environments of High-magnesian andesite and Related Rocks.

高镁质安山岩及相关岩石的成因环境。

• 批准号: 61540593
• 负责人: SATO Hiroaki
• 金额: $ 1.47万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61540593/
• 关键词: 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

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.

对四国东北部、能登半岛和九州西北部的高镁质安山岩以及小笠原群岛的栲泥岩进行了地质学、岩石学和化学研究。四国东北部的高镁安山岩（sanukitoid）可能代表源自水合地幔橄榄岩的原生安山岩，尽管源区可能受到俯冲沉积物的严重影响。能登半岛和九州西北部的青铜安山岩可能是由原始玄武岩和英安岩或流纹岩岩浆混合形成的。小笠原群岛栉泥石微量元素组成特点是HFSE较低，碱含量较高，碱土金属含量中等。这种富集（例如高 Rb/Ba 和 Ba/La 比率）在目前研究的高镁质安山岩中很常见，并且可以从岛弧拉斑玄武岩中诊断出来。一些火山岩的大气压熔融研究提供了一种新的氧逸度计。它利用斜长石和岩浆之间的Mg-Fe分配关系。氧逸度计的灵敏度约为 。 log fo_2=-6 - -11，并且可能对斜长石质火山岩具有广泛的适用性。

项目成果

佐藤博明他: 地質学雑誌.

佐藤宏明等人：地质杂志。

久城育夫,他: "日本の火成岩" 岩波書店, (1987)

九条郁夫等人：《日本火成岩》岩波书店（1987）

佐藤博明 他: 地質学雑誌.

佐藤宏明等人：地质杂志。