日本海拡大時の東北日本弧と西南日本弧の境界(<特集>関東平野下に伏在する東西日本の境界-地表および地下地質からのアプローチ-)  [in Japanese] Tectonic boundary between Northeast and Southwest Japan Arcs during Japan Sea opening(<Special Issue>Geotectonic boundary between Northeast and Southwest Japan concealed beneath the Kanto Plain-integrated approach of surface and subsurface geology-)  [in Japanese]

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Author(s)

    • 高橋 雅紀 Takahashi Masaki
    • 産業技術総合研究所地質情報研究部門地球変動史研究グループ Paleogeodynamics Research Group, Institute of Geology and Geoinformation, Geological Survey of Japan, AIST

Abstract

関東地方に分布する中新統の地理的および年代層序学的分布を総括し, 現在の利根川を挟んで岩相, 層厚, 地質構造, 堆積様式, 構造方向等に顕著な不連続を認めた.この地質学的不連続は, 西は赤城山の南麓下から伊勢崎と太田および館林の間を通り, さらに利根川に沿って柏付近から東方へ成田と竜ヶ崎の間に延び, さらに多古の北東付近で南東に向きを変え, 銚子の南の片貝海底谷へと延びる伏在断層である.この断層を挟んで東北日本弧と西南日本弧が大きく斜交しつつ接しており, その起源は前期中新世の日本海拡大時期に形成されたものと考えられる.断層に沿って相対的に東北日本弧が海溝側(東側)に数10km以上ずれており, また断層の西半部では落差の大きい南落ちの断層として, 平野側に厚い海成層を堆積させている.この断層をもって, 従来の利根川構造線を再定義した.

Tectonic boundary between Northeast (NE) and Southwest (SW) Japan arcs during Japan Sea opening is discussed based mainly on geographical and geochronological distribution of Miocene sediments in and around the Kanto district, central Japan. Geological discontinuity, such as thick marine sediments vs. volcaniclastics, and E-W vs. N-S structural trend of island arc, is recognized between the Kanto Mountains and the Ashio Mountains. The abrupt change in geological characters indicates a tectonic boundary between Miocene fore-arc region of SW Japan arc and volcanic province of NE Japan arc. This tectonic boundary can be traced to the east, where a sharp, steep, and straightlined submarine valley is recognized. Thus the previously presumed Tonegawa Tectonic Line is re-defined as a fault which was originated during Japan Sea opening in the Early Miocene, and divided the Japanese Islands into NE and SW Japan arcs in the Kanto district.

Journal

  • Journal of the Geological Society of Japan

    Journal of the Geological Society of Japan 112(1), 14-32, 2006-01-15

    The Geological Society of Japan

References:  115

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Cited by:  15

Codes

  • NII Article ID (NAID)
    110004027150
  • NII NACSIS-CAT ID (NCID)
    AN00141768
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    00167630
  • NDL Article ID
    7823331
  • NDL Source Classification
    ZM49(科学技術--地球科学--地質)
  • NDL Call No.
    Z15-174
  • Data Source
    CJP  CJPref  NDL  NII-ELS  J-STAGE 
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