| Project/Area Number |
08404028
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geology
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| Research Institution | The University of Tokyo (1998)
Tokyo Institute of Technology (1996-1997) |
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Principal Investigator |
ISOZAKI Yuko The Univ.of Tokyo, Graduate School of Arts & Sciences, Associate Professor, 大学院・総合文化研究科, 助教授 (90144914)
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| Co-Investigator(Kenkyū-buntansha) |
TANIMOTO Toshiro The Univ.of California Santa Barbara Inst.for Physics, Professor, サンタバーバラ校, 教授 (20262256)
HIRATA Takafumi Tokyo Inst.for Tech., College of Science, Associate Professor, 理学部, 助教授 (10251612)
YURIMOTO Hisayoshi Tokyo Inst.for Tech., College of Science, Associate Professor, 理学部, 助教授 (80191485)
MARUYAMA Shigenori Tokyo Inst.for Tech., College of Science, Professor, 理学部, 教授 (50111737)
NAKAMURA Yasuo The Univ.of Tokyo, Graduate School of Arts & Sciences, Professor, 大学院・総合文化研究科, 教授 (50011599)
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| Project Period (FY) |
1996 – 1998
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| Keywords | circum-Pacific / orogenic belt / continental growth / rift zone / subduction zone / supercontinent break-up / accretionary complex / Miyashiro-type orogeny |
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| Research Abstract |
Under the oceanic subduction setting beneath continetal margins. the present circum-Pacific regions represent typical subduction-driven orogenic belts. In the earlier half of this project, two major orogenic processes, i.e., gowth of accretionary complexes and that of granite batholith belts, have been analyzed, and the geoteconic framework and evolution of the Japanese Islands have been clarified. This scheme was exported and applied to understand the Californian (Cordiellan) geology in the western North America. These essential processes of continental margin growth are called the Miyashiro-type orogeny which rpresents a general mode of orogeny during the Wilson cycle between the birth and death of a superocean.
The latter part of this project was devoted for the analysis of the origin of the Japanese continental margin with special focus on the oldest rock in Japan. This project has revealed that ca. 580 Million year old ophiolites in western Kyushu and in the Kitakami mountains represent a piece of the oldest Pacific seafloor attached to the Yangtze (South China) continental margin. These ophiolites wer probably formed through the initial break-up of the supercontinent Rodinia ca. 700-600 m.y. ago. These are Quite consistent with the growth polarity of accretionary orogen in Japan, and suggests a tectonic conversion of a passive continental margin into an active one.
Thus this project on the Japanese Islands has led a general evolution model of a continental margin from supercontinent break-up.
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