2000 Fiscal Year Final Research Report Summary
Geochemical relationships between psammitic-pelitic rocks from the Sanbagawa Metamorphic Belt and Jurassic-Cretaceous accretionary complexes (Southern Chichibu-Nrothern Shimanto Belts)
| Project/Area Number |
09640546
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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 | Yamaguchi University |
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Principal Investigator |
KIMINAMI Kazuo Yamaguchi Univ., Fac.of Science, Professor, 理学部, 教授 (20127757)
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| Project Period (FY) |
1997 – 2000
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| Keywords | Shimanto Belt / Chichibu Belt / Sanbagawa Metamorphic Belt / clastic rock / chemical composition / Cretaceous / Jurassic |
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| Research Abstract |
Geochemical and petrological studies (meta-)sandstones and (meta-) pelite from the Sanbagawa Metamorphic Belt (chlorite zone), Jurassic Chichibu Belt and Cretaceous Shimanto Belt in Shikoku have been performed to find the non-metamorphic equivalents of the Sanbagawa metamorphic rocks. Following conclusions are obtained.
1. In the Chichibu Belt, Early Jurassic sandstones differ from Late Jurassic ones in terms of petrography and geochemistry.
2. Cretaceous sandstones in the Shimanto Belt, which are rich in volcanic rock fragments, change in petrological and geochemical featrures during the Turonian-Coniacian, and Can be divided into older KSI (I') and younger KSII (II') units. This classification is applicable from Kyushu to the Akaishi Nountains.
3. Metasandstones and metapelites from the Sanbagawa Metamorphic Belt have geochemical affinities with sandstones and shales in the Cretaceous Shimanto Belt. This evidence suggests that most of the sanbagawa metamorphic rocks are deeply underthrust facies of the Cretaceous Shimanto Supergroup.
4. the Oboke unil mainly composed of metasandstones is presumed to be the deeply underthrust facies of the Campanian Hiwasa Formation and/or its equivarent on the basis of lithofacies and geochemistry.
5. The Beshi unit of the Asemi area can be divided on the basis of chemical features into northern and southern parts of which metasandstones and metapelite are chemically similar to KSII and KSI units in the northern Shimanto Belt, respectively.
6. Metamorphosed units on the northern margin of the Chichibu Belt, westernmost Shikoku, can be partly correlative to the Togano unit and the rest with KSI/I' unit in the Cretaceous Shimanto Belt.
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