Geological studies of the greenstones in the northern Hidaka Zone

日高地区北部绿岩的地质研究

• 批准号: 02640595
• 负责人: MIYASHITA Sumio
• 金额: $ 1.15万
• 依托单位: Niigata 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: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02640595/
• 关键词: ophiolite; Hidaka zone; Shimokawa complex; Hokkaido; ocean ridge; オフィオラィト; 緑色岩; 四万十帯; 海嶺玄武岩

The results obtained from this research project are summarized as follows. 1) Geological and petrological studies on the Shimokawa, and Rurochi greenstone complexes of the northern Hidaka zone, the greenstones from the Makimine and Mugi Formations reveal that these greenstones are accompanied with no pelagic sediments such as chert and limestone, and extruded upon or intruded into terrigenous clastic sediments. 2) Geochemical signatures of these greenstones in terms of major and minor element chemistries exhibit that these greenstones are comparable with typical mid-ocean ridge basalts (N-MORB) and apparently different from island arc basalts. 3) Mineral chemistries of these greenstones are also similar with those of N-MORB and distinctive from those of island arc basalts and oceanic island basalts. Chemical zonings of plagioclases and clinopyroxenes of the greenstones indicate magmatic processes such as magma mixing and abrupt change of physical conditions during the crystallization of these greenstones. 4) On the basis of these lines of evidence, the greenstones are regarded to be extruded upon or intruded into unsolidified terrigenous sediments due to the collision of ocean ridge with trench.

从该研究项目中获得的结果总结如下。1)通过对北方日高带的下川、流内绿岩杂岩、真峰组和木木组绿岩的地质和岩石学研究，发现这些绿岩不含燧石、石灰岩等远洋沉积物，而是挤压或侵入陆源碎屑沉积物中。2)这些绿岩的地球化学特征的主要和次要元素化学方面显示，这些绿岩是典型的洋中脊玄武岩（N-MORB），显然不同于岛弧玄武岩。3)这些绿岩的矿物化学特征也与N-MORB相似，而与岛弧玄武岩和洋岛玄武岩不同。绿岩中斜长石和单斜辉石的化学分带指示了这些绿岩结晶过程中的岩浆混合和物理条件突变等岩浆作用。4)根据这些证据，认为绿岩是由于洋脊与海沟的碰撞而挤压或侵入到未固化的陆源沉积物中的。

项目成果

君波 和雄: "上部白亜系牟岐累層中のinーsitu緑色岩類の産状とその意義" 地質学雑誌. (1992)

Kazuo Kiminami：“上白垩统 Mugi 地层中原位绿岩的出现和意义”地质杂志（1992 年）。

君波 和雄: "上部白亜系四万十累層群槙峰層(九州)中の緑色岩の産状と化学組織" 地質学雑誌. 98. 391-400 (1992)

Kazuo Kiminami：“上白垩统四万十群（九州）马根组绿岩的产状和化学结构”地质杂志 98. 391-400 (1992)。

君波 和雄: "日高累層群中からの古第三紀放散虫化石の発見とその意義:特に海嶺の沈み込みについて" 地質学雑誌. 96. 323-326 (1990)

Kazuo Kiminami：“日高组古近纪放射虫化石的发现及其意义：特别是关于洋脊俯冲”地质杂志 96. 323-326 (1990)。

Sumio Miyashita: "A preliminary study on the zonings of plagioclase and clinopyroxene from the Shimokawa ophiolite, northern Hidaka zone, Hokkaido" Contrib. Dept. Geol. Min., Niigata Univ.7. 85-101 (1992)

Sumio Miyashita：“北海道日高地区北部下川蛇绿岩斜长石和单斜辉石分区的初步研究”Contrib。

Miyashita,S.: "Geology and bulkchemistry of the Shimokawa Ophiolite:ophiolite possibly generated near R-T-T triple junction" Proc.29th International Geol Cong.(1993)

Miyashita,S.：“下川蛇绿岩的地质学和整体化学：可能在 R-T-T 三重连接点附近生成蛇绿岩”Proc.29th International Geol Cong.(1993)