ID | 117533 |
Title Alternative | The Mikabu and Chichibu belts in the Iya-gawa area, Tokushima Prefecture, Shikoku, SW Japan : An integrated research of geology and geomorphology
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Author |
Ishida, Keisuke
University of Tokushima
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Nishiyama, Ken-ichi
University of Tokushima
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Nakao, Ken-ichi
Tokushima Prefectural Museum
Motoyama, Shigeki
Tokushima City High School
Takaya, Seiji
Minami Kyushu University
Kozai, Takeshi
Naruto University of Education
Ozawa, Hiroaki
Naruto University of Education
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Keywords | terrane analysis
Mikabu Greenstone
North Chichibu Belt
landslide
swelling clay
environmental geology
Iya-gawa River
Tokushima Prefecture
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Content Type |
Departmental Bulletin Paper
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Description | The Mikabu and Chichibu belts in the Iya-gawa area are studied with respect to their composition, boundaries and the relation with landslides. The Kyobashira-Sugeoi Fault bound the Mikabu Greenstone Belt from the Sambagawa Belt. The Kubo Greenstone body, a part of the Mikabu Greenstone, distributes as an axial part of antiform in the southern margin of the Sambagawa Belt. The Mikabu Greenstone of the area is composed of tholeiitic and alkaline rocks. The Mikabu Greenstone thrust to the south with the Okoyatoko-Nagoro Fault upon the Jurassic accretionary complex of the North Chichibu Belt. Even the phillite generally dipping towards the north in the northern part of the North Chichibu Belt, the oceanic-plate successions of chert-mudstone sequences are stratigraphically upper towards the south. The radiolarian age, estimated at the lithological transition from chert to mudstone in the oceanic-plate sequences, is Early Jurassic. The landslides concentrate in the areas of the Mikabu Greenstone and valley walls along the Iya-gawa River. The linear depressions and ponds, arrange on the mountain ridge between the Miune and Tengu-Zuka along the southern border of the Mikabu Greenstone, are regarded as a sign of large-scale collapse by long-period gravitational mass rock deformation of the mountain body. The weathered zone of the Mikabu Greenstone often includes swelling clay that causes landslides in the area.
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Journal Title |
Natural Science Research
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ISSN | 09146385
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NCID | AN10065859
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Publisher | 徳島大学総合科学部
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Volume | 21
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Start Page | 47
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End Page | 64
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Sort Key | 47
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Published Date | 2007-12-21
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EDB ID | |
FullText File | |
language |
jpn
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TextVersion |
Publisher
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departments |
Science and Technology
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