Ophiolites of Japan.
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- ISHIWATARI Akira
- Department of Earth Sciences Kanazawa University
Bibliographic Information
- Other Title
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- 日本のオフィオライト
- ニホン ノ オフィオライト
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Abstract
The Japanese ophiolites are divided into nappe type and melange type by their occurrences. The nappe type formed in a short period (a few 10Ma), and emplaced shortly after its igneous formation keeping its original igneous stratigraphy. They generally escaped from post-emplacement, high-pressure metamorphism. The melange type is a mixture of ophiolitic fragments of various ages (a few 100Ma) and lithologies, and most of them are affected by high-pressure metamorphism. The age of igneous formation of the Japanese ophiolites ranges from early Paleozoic to Cenzoic. Large nappe-type ophiolites formed in Ordovician, Permian, Jurassic, and Cretaceous periods, corresponding to the world-wide ophiolite pulses. The Paleozoic ophiolites are mainly distributed in Honshu, while the Mesozoic ophiolites are in Hokkaido. The Cenozoic melange-type ophiolites occur in front of the Izu arc, which collided against Japan in Miocene.<BR>The residual peridotite of Japanese ophiolites ranges from fertile lherzolite to highly depleted harzburgite. Mafic-ultramafic cumulates show diverse crystallization sequences including plagioclase, clinopyroxene, and orthopyroxene types. MORBs are dominant among the ophiolitic volcanics, while picrites and alkali basalts are also common among melangetype ophiolites. A few ophiolites bear calc-alkali rocks or hydrous mantle peridotite suggestive of island-arc origin. Pervasive pre-emplacement metamorphism of the cumulate rocks in the amphibolite and granulite facies as well as the absence of sheeted dike complexes are common features of the Japanese ophiolites.
Journal
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- Journal of Geography (Chigaku Zasshi)
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Journal of Geography (Chigaku Zasshi) 98 (3), 290-303, 1989
Tokyo Geographical Society
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Keywords
Details 詳細情報について
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- CRID
- 1390282679205489024
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- NII Article ID
- 130001001287
- 10003545737
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- NII Book ID
- AN00322536
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- ISSN
- 18840884
- 0022135X
- http://id.crossref.org/issn/0022135X
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- NDL BIB ID
- 3242527
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- Text Lang
- ja
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- Data Source
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- JaLC
- NDL
- Crossref
- CiNii Articles
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- Abstract License Flag
- Disallowed