岡山県成羽町北西地域の地質

廣島大學地學研究報告 Issue 14 Page 397-425 published_at 1965-02-22
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Title ( jpn )
岡山県成羽町北西地域の地質
Title ( eng )
Geology of the Northwestern Part in Nariwa-machi, Okayama Prefecture, Japan
Creator
KUSUMI Hisashi
YOSHIMURA Norihisa
KATAYAMA Sadaaki
Source Title
廣島大學地學研究報告
Geological report of the Hiroshima University
Issue 14
Start Page 397
End Page 425
Abstract
This district is situated in the central part of the Kibi plateau which is considered as an elevated peneplain, and has been studied by a lot of geologists and palaeontologists because of abundant occurrences of animal and plant fossils and its complicated geologic structures.
The stratigraphy of the district is summarized as follows:
[Original table is skipped. For more details, please refer to the full text.]
The Palaeozoic rocks are composed of calcareous and non-calcareous groups. The latter consists of non-fossiliferous sandstone, shale and chert, and is named the Fuka formation. The former can be subdivided into 2 members by the lithofacies; the lower is the schalstein-bearing Nakamura limestone group, while the upper is called the Uji formation mainly composed of shale and schalstein sometimes with limestone nodules. From the evidence of fusulinids the calcareous formations are assigned to the Pennsylvanian-Middle Permian in age.
The "Inkstone" group, which forms a basin structure, can be subdivided into two parts by the presence of limestone conglomerate; i. e. the upper is composed of the thick red tuff beds, while the lower of the thick limestone conglomerate and thin red tuff layers. The limestone conglomerate is limited to occur in the vicinities of the huge limestone bodies. Judging from the lithofacies, the "Inkstone" group in this district might be the sediments mainly of pyroclastic materials and deposited in a small narrow basin which was due to the Ohga thrust movement.
The Palaeozoic Nakamura limestone group thrusts over the Norian Nariwa group, and both of them are covered unconformably by the "Inkstone" group and later extruded andesite and rhyolite masses successively. Therefore, the Ohga thrust movement might be happened in pre-"Inkstone" time.
Descriptions
今村外治教授退官記念特集号
Language
jpn
Resource Type departmental bulletin paper
Publisher
廣島大學理學部地學教室
Date of Issued 1965-02-22
Publish Type Version of Record
Access Rights open access
Source Identifier
[ISSN] 0073-2303
[NCID] AN00213676