| Project/Area Number |
04640705
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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 |
地質学一般
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
HARA Ikuo Hiroshima Univ., Faculty of Science, Professor., 理学部, 教授 (50033824)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASAKA Yasutaka Hiroshima Univ.Faculty of Science, Research Associate, 理学部, 助手 (10198830)
MIYAMOTO Takami Hiroshima Univ.Faculty of Science, Associate Professor, 理学部, 助教授 (00090548)
TAKESHITA Toru Hiroshima Univ., Faculty of Science, Associate Professor, 理学部, 助教授 (30216882)
櫻井 康博 広島大学, 理学部, 助手 (80205814)
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| Project Period (FY) |
1992 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1993: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Sambagawa megaunit / Chichibu megaunit / metamorphic rocks of high-pressure type / Subduction zone / tectonic erosion / underplating / P-T-t-D path / folding mechanism / ナップ / 運動像 / フレクシュラル・スリップ / シース褶曲 / 石英ファブリック / 放射年代 / 高圧変成岩の上昇機構 / two way Streets model / 付加体 / 雁行褶曲群 / 雁行石英脈群 / 左横ずれ剪断 |
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| Research Abstract |
The Outer Zone of Southwest Japan consists of the four megaunits.Chichibu megaunit II,Sambagawa megaunit.Chicibu megaunit I and Shimant megaunit in descending order of structural level.On the basis of microtextures of the Sambagawa megaunit rocks, especially Saruta nappe (I+II) schists and Fuyunose nappe schists, it has been clarified that in subduction channel sediment subduction occurs a accompanying tectonic crosion and mixing of the hanging wall rocks.From analysis of microtextures and P-T-t-D path of the Sogauchi nappe schists, it has been pointed out that they consist of three subnappes, ST subnappe, KAT subnappe and NOM subnappe in descending oreder of structural level, which are succesively underplated with downward decrease of pressure and temperature, and that the underplating processes is ascribed to upflow of subducted sehiments from control point of subduction channel.From relationship in microtextures and P-T-t-D path between the Sogauchi nappe schists and the Sakamoto-Niyodo nappe schists (Chichibu megaunit I), it has benn concluded that the Sambagawa megaunit schists as metamorphic rocks of high-pressure type were exhumed along the mechanial boundary of the Cretaceous convergence zone.The folding of the Sambagawa megaunit schists during the last phase of deformation shows a transition from flexural-flow type to flexural-slip type.
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