群馬県高崎地域に分布する中新統 : とくに庭谷不整合形成過程について

• 大石, 雅之

• 高橋, 雅紀

書誌事項

タイトル別名

• グンマケン タカサキ チイキ ニ ブンプスル チュウシントウ トクニ ニワヤ
• Miocene formations in the Takasaki district, central Japan : With special reference to the developmental process of the Niwaya Unconformity

抄録

application/pdf

Miocene formations in the Takasaki district are distributed along the northern margin of the Kanto Mountains. These Miocene strata unconformably overlie pre-Neogene granitic rocks, the Kanohara Conglomerate and the Kottateyama Tuff and are in fault contact with the Sanbagawa metamorphic rocks. This series is divided into the following seven units, in ascending order : Ushibuse Formation (400m+thick), Obata Formation (900m), Idozawa Formation (450m), Haratajino Formation (40m), Niwaya Formation (400m-), Haraichi Formation (550m)and Itahana Formation (1200m). The Niwaya Formation overlies the Haratajino, Idozawa and Obata Formations with partial unconformity. Miocene tectonic evolution in this area is summarized as follows. In the early Middle Miocene (zone N. 8), arkosic sand and silt were deposited in an upper～middle bathyal environment (Konda, 1980). At the time of zone N. 9, the Takasaki area underwent NE-SW shortening deformation : reverse faulting and folding. Many minor faults formed in this time show NE-SW trending σ_1. The eastern part of the study area was uplifted on account of this deformation and the crests of the folded strata were eroded to form the Niwaya Unconformity. While in the western area, sedimentation continued during this period. This unconformity seems to have progressed in association with the opening of the Japan Sea (14.9Ma : Otofuji et al., 1985). In the middle to late Middle Miocene (zone N.10～N.14), sand and silt were deposited in a lower sublittoral～upper bathyal environment. The low sediment accumulation rate indicates slow subsidence of the Takasaki district. Many normal faults were formed during (or after) this period under E-W～NW-SE extensional stress field. In the late Middle Miocene time, coarse sand and gravel filled the shallow sea to lead to land areas accreting gradually.

紀要類(bulletin)

1513375 bytes

収録刊行物

• 東北大學理學部地質學古生物學教室研究邦文報告

  東北大學理學部地質學古生物學教室研究邦文報告 92 1-17, 1990-04-15

  東北大學

詳細情報

• CRID: 1050282677707939200
• NII論文ID: 110004645403
• NII書誌ID: AN00171452
• ISSN: 00824658
• HANDLE: 10097/33213
• NDL書誌ID: 3676416
• Web Site: https://tohoku.repo.nii.ac.jp/records/13086
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I3676416
• 本文言語コード: ja
• 資料種別: departmental bulletin paper
• データソース種別:
  • IRDB
  • NDL
  • CiNii Articles