UPLIFT TECTONICS OF THE HIGH-PRESSURE SANBAGAWA METAMORPHIC BELT

高压三八川变质带隆起构造

• 批准号: 03640644
• 负责人: ISOZAKI Yukio
• 金额: $ 1.22万
• 依托单位: Yamaguchi 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: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03640644/
• 关键词: nappe; low-angle faults; accretionary complex; sandwich structure; geotectonic window; klippe; tectonic uplift; KーAr年代; 低温高圧型変成作用

Field survey and in-door works have been conducted in the 2 years research project, and following new results were obtained. 1) The Cretaceous Sanbagawa high-P/T metamorphic rocks occur tectonically above the weakly metamorphosed Late Cretaceous accretionary complex of the Shimanto belt in western, central and eastern Kii Peninsula, Southwest Japan. The boundary between them is a low-angle thrust which was recognized for the first time in Southwest Japan. 2) The Sanbagawa metamorphic rocks, on the contrary, tectonically underlie the weakly metamorphosed Jurassic accretionary complex of the Chichibu belt in central and eastern Shikoku. The boundary between them is a low-angle normal fault. These relations suggest that the Sanbagawa metamorphic rocks form a subhorizontal nappe, bounded from tectonically over-and under-lying units by low-angle faults. 3) Difference in metamorphic grades among these juxtaposed units forming a sandwich, indicates that the boundary faults represent remarkabl … More e pressure gap more than some kilobars. 4) The Sanbagawa belt in southwest Japan can be re-defined as an area of geotectonic window where the Sanbagawa metamorphic rocks are exposed by removal of tectonically overlying Jurassic accretionary complex. 5) The thickness of the Sanbagawa nappe is less than 2km, and this suggests its peculiar uplift tectonics from the metamorphic domain in the deeper part of subduction zone. 6) Judging from the timing of the Kula-Pacific ridge subduction, uplift of the Sanbagawa metamorphic rocks was led by wedge extrusion mechanism induced by ridge subduction along continental margin. These results are noteworthy because they not only renewed the total understanding of geotectonic history of Japan but also gave a new aspect in the study of orogeny, in particular, of the formation processes of the Cordilleran-type orogenic belts in general. Parts of the above-mentioned results were already presented orally and published in scientific articles elsewhere of this report. Less

在两年的研究项目中，进行了野外调查和室内工作，取得了以下新成果。1)白垩纪Sanbagawa高P/T变质岩产于日本西南部Kii半岛西部、中部和东部岛曼都带晚白垩世弱变质的增生杂岩之上。它们之间的边界是低角度逆冲，这在日本西南部首次被发现。2)四国中部和东部赤部带侏罗纪弱变质增生杂岩的构造背景为三巴川变质岩。它们之间的边界是一条低角度正断层。这些关系表明，三巴川变质岩形成了一种次水平推覆，由低角度断层从构造上、下单元包围。3)夹层状并置单元的变质级别不同，表明边界断裂代表明显的…。比千巴更大的压差。4)日本西南部的三叶川带可重新定义为三叶川变质岩通过剥离上覆侏罗纪增生杂岩而露出的大地构造窗口区。5)桑巴加瓦推覆体厚度不到2公里，表明其独特的隆升构造来自俯冲带深部的变质域。6)从库拉-太平洋海脊俯冲的时间来看，三巴川变质岩的抬升是由海脊俯冲导致的大陆边缘楔形挤压机制导致的。这些结果值得注意，因为它们不仅更新了对日本大地构造史的全面认识，而且为造山作用的研究，特别是科迪勒型造山带的形成过程提供了一个新的方面。上述部分成果已经口头提出，并在本报告其他地方的科学文章中发表。较少

项目成果

Isozaki, Y., Hashiguchi, T. and Itaya, T.: "The Kurosegawa klippe: an examination." Jour.Geol.Soc.Japan. vol.98,no.10. 917-941 (1992)

Isozaki, Y.、Hashiguchi, T. 和 Itaya, T.：“黑濑川飞来峰：一次检查。”

河戸 克志・磯崎 行雄・板谷 徹丸: "四国中央部における三波川・秩父累帯間の地体構造境界" 地質学雑誌. 97. 959-975 (1991)

Katsushi Kawato、Yukio Isozaki 和 Tetsumaru Itaya：“四国中部三波川带和秩父带之间的大地构造边界”地质杂志 97. 959-975 (1991)。

河戸 克志,磯崎 行雄,板谷 徹丸: "四国中央部における三波川帯・秩父累帯間の地体構造境界" 地質学雑誌. 97. 959-975 (1991)

Katsushi Kawato、Yukio Isozaki、Tetsumaru Itaya：“四国中部三波川带和秩父带之间的大地构造边界”地质杂志 97. 959-975 (1991)。

Isozaki,Y.and Itaya,T.: "Pre-Jurassic klippe in northern Chichibu belt in west-central Shikoku,Southwest Japan." Jour.Geol.Soc.Japan. vol.97,no.6. 431-450 (1991)

Isozaki,Y. 和 Itaya,T.：“日本西南部四国中西部秩父带北部的前侏罗纪飞来峰。”

佐々木 洋大,磯崎 行雄: "紀伊半島中央部、三波川帯・四万十帯間の低角度スラスト" 地質学雑誌. 98. 57-60 (1992)

佐佐木洋弘，矶崎由纪夫：“纪伊半岛中部三波川带和四万十带之间的低角度逆断层”地质杂志 98. 57-60 (1992)。