208-240 M.Y. OLD JADEITE-GLAUCOPHANE SCHISTS IN THE KUPOSEGAWA TECTONIC ZONE NEAR KOCHI CITY, SHIKOKU
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- MARUYAMA SHIGENORI
- Department of Earth Sciences, Faculty of Science, Nagoya University Department of Earth Science, Faculty of Education, Toyama University
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- UEDA YOSHIO
- Institute of Mineralogy, Petrology and Economic Geology, Tohoku University
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- BANNO SHOHEI
- Department of Earth Sciences, Faculty of Science, Kanazawa University
Bibliographic Information
- Other Title
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- 四国高知市付近の黒瀬川構造帯に産する208-240 m.y.の放射性年代を示すヒスイ輝石-藍閃石片岩
Abstract
A new member of the Kurosegawa tectonic zone was found in the serpentinite near Kochi city. They are high P and low T schists derived from basalt and chert.<br> Three metamorphic events can be deciphered in the high-pressure schists, based upon the texture and mineral paragenesis: first, low P metamorphism at intermediate- to highgrade, second, high P and low T metamorphism of the jadeite-glaucophane facies and the thrid, retrograde crystallization of the second stage high P schists within the stability field of lawsonite+pumpellyite+glaucophane. Further, the formation of analcime replacing jadeite took place. The second and third metamorphism can be distinguished on pyroxene mineralogy that jadeite+quartz was stable in the second, but albite+quartz+aegirinejadeite in the third stage of metamorphism.<br> Not all of the high P and low T schists had suffered low P metamorphism before they were metamorphosed by the high P one. Some basaltic rocks directly changed to high P and low T schists.<br> Two muscovites in the schists give K-Ar ages of 208-240 m.y., and a relic igneous biotite, being partly replaced by chlorite, gives 225 m.y. of K-Ar age. These values are different not only from those of the Sanbagawa schists, but also from the other members of the Kurosegawa zone.
Journal
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- The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
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The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists 73 (10), 300-310, 1978
Japan Association of Mineralogical Sciences
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Details 詳細情報について
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- CRID
- 1390001206217147648
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- NII Article ID
- 130003728389
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- ISSN
- 18830765
- 00214825
- http://id.crossref.org/issn/03610128
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- Data Source
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- JaLC
- Crossref
- CiNii Articles
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- Abstract License Flag
- Disallowed