2000 Fiscal Year Final Research Report Summary
Time-Space of the evolution of the Hida metamorphic rocks based on CHIME age
| Project/Area Number |
10640435
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Toyama University |
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Principal Investigator |
SOHMA Tsuneo Toyama Univ., Faculty of Education, Professor, 教育学部, 教授 (40019039)
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| Co-Investigator(Kenkyū-buntansha) |
YOKOYAMA Kazumi National Science Museum, Department of Geology, Head, 地学研究部, 室長 (40126628)
GOTO Atsushi Himeji Institute of Technology, Faculty of Science, Research Assistant, 理学部, 助手 (50211917)
KUNUGIZA Keitaro Faculty of Education, Toyama University, Associate Professor, 教育学部, 助教授 (30225180)
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| Project Period (FY) |
1998 – 2000
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| Keywords | CHIME / U-Th-Pb chemical age / Hida metamorphic belt / Hida metagranitoid / Funatsu granitoid / Unazuki metamorphic belt / zircon / uraninite |
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| Research Abstract |
The time and space of the evolution of the Hida metamorphic belt were studied on the basis of U-Th-Pb chemical age (CHIME age) of zircon, monazite, uraninite and thorite. This study is an extention of the petrological studies of the Hida metamorphic rocks (Sohma et al., 1995), in which mother-daughter relationships (relative age relationship) of various rock types were determined. The followings are the major conclusions of this study.
1 CHIME age of U-Th-Pb minerals of a collision type metamorphic belt were controled by hydrothermal reactions rather than closure temperature of the minerals.
2 The majority of the so called Jurassic Funatsu granitoids show Carboniferous to Permian zircon ages in origin, and possess monazite and uraninite of the Hida metamorphic age of 240Ma. They are metamorphic rocks, and will be called the Hida metagranitoids.
3 The Unazuki metamorphic belt is not a separate one, but has been developed as a part of the Hida metamorphic belt, because of the association of the Unazuki metamorphic rocks and the Hida metagranitoids.
4 The Hida metamorphic belt is a polymetamorphic orogen, but its lithology were finally formed at about 270Ma.
5 The Hida metamorphism started with subduction zone granitic magmatism at about 270Ma, showed a thermal peak followed by a hydrothermal event in which uraninite of 240Ma age crystallized, and continued to the uplift and cooling of the metamorphic belt as indicated by K-Ar ages of hornblende and biotite.
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Research Products
(4 results)
