Geology and age of Miocene Series in the Minakami area, northern Gunma Prefecture, central Japan
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- Takahashi Masaki
- Geological Survey of Jpan
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- Saito Kazuo
- Department of Earth Sciences, Yamagata University
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- Umetsu Hiroyuki
- IG-Technical Research Inc.
Bibliographic Information
- Other Title
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- 群馬県北部水上地域に分布する中新統の地質と年代
- グンマケン ホクブ ミナカミ チイキ ニ ブンプスル チュウシントウ ノ チシ
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Abstract
Miocene fromations widely overlie the Mesozoic formation, ultramafic rocks and Cretaceous granite in the Minakami area, northern part of Gunma Prefecture. This series is divided into the following six formations, in ascending order: Okura Formation (300 m in thickness), Awazawa Formation (550 m), Gokan Formation (260-2600 m), AkayaFormation (200 m+), Mitsumineyama Formation (350 m) and Tone Welded Tuff (200 m). The Gokan Formation unconformably overlies the underlying formations. The Mitsumineyama Formation and Tone Welded Tuff unconformably cover the Gokan and the Akaya Formations. Late Cenozoic tectonic evolution in this area is summarized as follows. In the Early Miocene, a large amount of basalt erupted on land. Many dykes of basalt show NE-SW trendingσ_<H-max>. In the earliest Middle Miocene, felsic pyroclastics deposited in shallow seas. The feeder dykes of the andestie-rhyolite show NE-SW trending σ_<H-max>. In the early Middle Miocene (15-14 Ma), mud deposited in lower middle bathyal environment. In the latest Middle Miocene (11 Ma), dacitic pyroclastics deposited on land and no more major geologic deformation have not occurred since then.
Journal
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- Earth Science (Chikyu Kagaku)
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Earth Science (Chikyu Kagaku) 45 (6), 435-452, 1991
The Association for the Geological Collaboration in Japan
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Details 詳細情報について
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- CRID
- 1390282679210269056
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- NII Article ID
- 110007092690
- 10014709432
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- NII Book ID
- AN00141269
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- ISSN
- 21897212
- 03666611
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- NDL BIB ID
- 3740815
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- Text Lang
- ja
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- Data Source
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- JaLC
- NDL
- CiNii Articles
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- Abstract License Flag
- Disallowed