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An overview of the Miocene tectonics in the Southwest Japan Arc from radiometric dating

Research Project

Project/Area Number 20K04136
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 17040:Solid earth sciences-related
Research InstitutionTokyo Keizai University

Principal Investigator

Shnjoe Hironao  東京経済大学, 全学共通教育センター, 教授 (60312013)

Co-Investigator(Kenkyū-buntansha) 平田 岳史  東京大学, 大学院理学系研究科(理学部), 教授 (10251612)
折橋 裕二  弘前大学, 理工学研究科, 教授 (70313046)
Project Period (FY) 2020-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2022: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2021: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2020: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Keywords西南日本弧 / 日本海形成 / 中新世 / マグマ活動 / ウラン・鉛年代 / 瀬戸内火山岩類 / 火成活動 / U-Pb年代 / フィリピン海プレート / 日本海拡大 / 即発γ線分析 / 沖縄トラフ / 放射年代測定
Outline of Research at the Start

日本列島がユーラシアが大陸から分離した時期(およそ2000万年~1500万年前)について,その当時活動したマグマ活動で形成された岩石の年齢の決定を中心に詳しく探求する.特に西日本は列島が時計廻りをして大陸と分離したとされるため,その回転の時期の決定を中心に探求する.化学分析から得られたマグマの性質やその活動時代の情報を合わせて総合的に検討し,当時の日本列島の周辺のプレート(岩盤)の配置の様子について解明し,日本列島,とりわけ西日本の地史の復元に役立つモデルを考察する.

Outline of Final Research Achievements

Southwest Japan underwent separation from the Asian continent through a clockwise rotation during the middle Miocene, yet numerous aspects concerning the timing and mechanisms of this event remain poorly understood. This study focused on examining the characteristics and dating the distinctive magmatic activities trench-proximal region of Southwest Japan, both preceding and following the rotation, to constrain the timing of this rotation and the contemporaneous plate configurations. Our findings reveal that the Setouchi Volcanic Rocks extend to the Amakusa area in western Kyushu. Furthermore, the formation age of the Murotomisaki Gabbro, which likely resulted from magma intrusion originating from the Shikoku Basin, is dated to approximately 15.6 million years ago. These results support the hypothesis that the rotation of Southwest Japan concluded 16 million years ago, with the Southwest Japan arc facing the Shikoku Basin on the Philippine Sea Plate at the cessation of this rotation.

Academic Significance and Societal Importance of the Research Achievements

日本海の形成は日本列島が大陸から分離し,ほぼ現在の弧状列島の形となった出来事であった.したがって,日本海形成前後に起こった様々な地質学的な現象は,日本列島の地史を復元する上で重要な研究対象であると言える.本研究は特に西南日本が時計回り回転をして大陸から離れた時期とほぼ同時に起こったマグマ活動に着目して,マグマ活動の起こった時期やその成因について考察し,当時の西南日本の地質発展史の解明に寄与するものである.

Report

(5 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Research-status Report
  • 2021 Research-status Report
  • 2020 Research-status Report
  • Research Products

    (11 results)

All 2023 2022 2021 2020

All Journal Article (6 results) (of which Peer Reviewed: 5 results,  Open Access: 2 results) Presentation (5 results) (of which Int'l Joint Research: 1 results)

  • [Journal Article] Geochronological and petrological investigations of Miocene felsic igneous rocks in the Amakusa Islands, southwest Japan: Possible extension of the Setouchi Volcanic Belt2023

    • Author(s)
      Shinjoe Hironao、Orihashi Yuji、Akasaka Mana、Niki Sota、Sasaki Minoru、Hirata Takafumi
    • Journal Title

      Island Arc

      Volume: 33 Issue: 1

    • DOI

      10.1111/iar.12506

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] 中部地方,設楽地域の津具火山岩類の全岩化学組成(予報)2023

    • Author(s)
      新正裕尚,折橋裕二
    • Journal Title

      東京経済大学人文自然科学論集

      Volume: 153

    • Related Report
      2022 Research-status Report
    • Open Access
  • [Journal Article] Zircon U-Pb age of the acidic tuff from the Miocene Kuma Group, western Shikoku2021

    • Author(s)
      新正裕尚.折橋裕二
    • Journal Title

      The Journal of the Geological Society of Japan

      Volume: 127 Issue: 10 Pages: 595-603

    • DOI

      10.5575/geosoc.2021.0020

    • NAID

      130008138600

    • ISSN
      0016-7630, 1349-9963
    • Year and Date
      2021-10-15
    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Journal Article] Zircon U-Pb ages of Miocene granitic rocks in the Koshikijima Islands: Implications for Neogene tectonics in the Kyushu region, SW Japan2021

    • Author(s)
      Hironao Shinjoe, Yuji Orihashi, Sota Niki, Aki Sato, Minoru Sasaki, Tomoaki Sumii, Takafumi Hirata
    • Journal Title

      Island Arc

      Volume: 30 Issue: 1

    • DOI

      10.1111/iar.12383

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Journal Article] Identification of the source caldera for the Middle Miocene ash‐flow tuffs in the Kii Peninsula based on apatite trace‐element composition2021

    • Author(s)
      Reishi Takashima, Hiroyuki Hoshi, Yutaka Wada, Hironao Shinjoe
    • Journal Title

      Island Arc

      Volume: 30 Issue: 1 Pages: 1-15

    • DOI

      10.1111/iar.12404

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Journal Article] Formation process of the vein in the Nakamura formation of the Mizunami Group2020

    • Author(s)
      古川邦之、西本昌司、金丸龍夫、和田穣隆、新正裕尚
    • Journal Title

      The Journal of the Geological Society of Japan

      Volume: 126 Issue: 12 Pages: 697-712

    • DOI

      10.5575/geosoc.2020.0039

    • NAID

      130008005151

    • ISSN
      0016-7630, 1349-9963
    • Year and Date
      2020-12-15
    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Presentation] 室戸岬斑れい岩体のジルコンU-Pb年代と中期中新世西南日本沈み込み縁辺における位置付け2023

    • Author(s)
      新正 裕尚・羽地 俊樹・仁木 創太・折橋 裕二・佐々木 実・平田 岳史
    • Organizer
      日本地質学会第130年学術大会
    • Related Report
      2023 Annual Research Report
  • [Presentation] Trench-proximal felsic magmatsim in Miocene southwest Japan2023

    • Author(s)
      Hironao Shinjoe, Yuji Orihashi
    • Organizer
      Xth Hutton Symposium
    • Related Report
      2023 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 放射年代と全岩化学組成に基づく九州西部天草地域の中新世貫入岩の起源の検討2022

    • Author(s)
      新正裕尚,赤坂真奈,折橋裕二,仁木創太,佐々木実,平田岳史
    • Organizer
      日本地質学会第129年学術大会
    • Related Report
      2022 Research-status Report
  • [Presentation] 西南日本海溝寄り地域の中新世火成岩の活動時期と西南日本回転直後のプレート配置の検討2022

    • Author(s)
      新正裕尚,折橋 裕二,安間了
    • Organizer
      東京大学大気海洋研究所研究集会「フィリピン海プレート北端部テクトニクスの再検討」
    • Related Report
      2022 Research-status Report
  • [Presentation] 紀伊半島の瀬戸内火山岩類の活動時期について2021

    • Author(s)
      新正 裕尚,和田 穣隆,折橋 裕二
    • Organizer
      日本地質学会第128年学術大会
    • Related Report
      2021 Research-status Report

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Published: 2020-04-28   Modified: 2025-01-30  

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