2000 Fiscal Year Final Research Report Summary
Crust-Mantle Interaction in Continental Collision Zones
| Project/Area Number |
11691125
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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 | 海外学術 |
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| Research Field |
Geology
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| Research Institution | Nagoya University (2000)
Kyoto University (1999) |
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Principal Investigator |
WALLIS Simon Graduate School of Science, Nagoya University, Associate Professor, 大学院・理学研究科, 助教授 (30263065)
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| Co-Investigator(Kenkyū-buntansha) |
KATO Takenori Nagoya University, Center for Chronological Research, Instructor, 年代測定総合研究センター, 助手 (90293688)
SUZUKI Kazuhiro Nagoya University, Center for Chronological Research, Professor, 年代測定総合研究センター, 教授 (90111624)
ENAMI Masaki Graduate School of Science, Nagoya University, Professor, 大学院・理学研究科, 教授 (20168793)
HIROI Yoshikuni Chiba University, Faculty of Science, Professor, 理学部, 教授 (40019427)
HIRAJIMA Takao Kyoto University, Graduate School of Science, 大学院・理学研究科, 助教授 (90181156)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Continental Collision / Ultrahigh-Pressure Metamorphism / Eastern China / Pressure-Temperature Paths / Exhumation Rates / Chemical Recycling / Eclogite |
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| Research Abstract |
The main results of our work can be summarized as follows.
1) The northern part of the Sulu UHP terrane is characterized by isothermal decompression. In addition the prograde P-T path has been closely constrained and shows a very low thermal gradient. Both the prograde and decompression paths can be used in conjunction with quantitative thermal modelling to test tectonic models. Qualitatively both P-T paths suggest rapid burial and exhumation of the whole UHP Sulu terrane.
2) Studies of UHP metamorphic rocks have identified the carrier minerals for a variety of elements such as Sr important in understanding the recycling of continental crust in convergent plate margins. The stability of these minerals will control the regions in collision zones where the elements may be released.
3) A new discovery of a body of high-pressure eclogitic rocks in southwest Japan is particularly significant because it probably has a distinct P-T path from other similar rocks to the west. This difference can help constrain the along strike 3-d thermal history of the region.
4) Research on the age and rates of orogenesis has still to be published. However, preliminary results give an age of deformation of c. 230 Ma contemporaneous with metamorphism. The structures can, therefore, be used to constrain tectonic models related to metamorphism and collision. In addition, a study of the size and density of blocks entrained in the regional acidic gneisses of the Sulu terrane suggests that the exhumation rate was of the order of cm per year. This in turn places constraints on the possible viscosities of the lower crust - one of the least clear parameters in any quantitative model of collision.
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[Publications] Banno,S.,Enami,M.,Hirajima,T.,Ishiwatari,A.,and Wang,Q.: "Decompression P-T path of coesite-eclogite to granulite from Weihai, Eastern China."Lithos. (印刷中). (2000)
Description
「研究成果報告書概要(和文)」より
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