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Stratigraphic correlation using tephra beds and calcareous nannofossil bioevents for understanding forearc tectonics

Research Project

Project/Area Number 20K14568
Research Category

Grant-in-Aid for Early-Career Scientists

Allocation TypeMulti-year Fund
Review Section Basic Section 17030:Human geosciences-related
Research InstitutionNational Institute of Advanced Industrial Science and Technology

Principal Investigator

Utsunomiya Masayuki  国立研究開発法人産業技術総合研究所, 地質調査総合センター, 主任研究員 (10738313)

Project Period (FY) 2020-04-01 – 2023-03-31
Project Status Completed (Fiscal Year 2022)
Budget Amount *help
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2022: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2021: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Keywords石灰質ナノ化石 / テフラ / 不整合 / 層序 / 海底地すべり / 前弧海盆 / 年代層序 / 黒滝不整合 / 堆積盆 / 新生代 / テクトニクス
Outline of Research at the Start

南関東は海洋プレートが沈み込むとともに島弧同士が衝突している世界で最も活動的な地域の一つである.この結果,約500万~50万年前の相模トラフ沿いでは海溝斜面盆と前弧海盆が発達し,衝突帯でも堆積盆が発達した.これら異なる堆積盆に記録された地質学的イベントの前後関係が明らかになれば,プレート沈み込みと島弧衝突テクトニクスの解明に大きく貢献できる.本研究ではテフラ層(火山灰など火山噴出物)のカタログ的記載と化学分析,及び海成層の年代決定にきわめて有効な微化石である石灰質ナノ化石によって堆積盆間の高精度対比を行い,各堆積盆が記録する地質学的イベントの前後関係を明らかにする.

Outline of Final Research Achievements

Forearc sedimentary basins developed in the southern Kanto region during the Late Cenozoic under the influence of plate subduction and collision tectonics. In this study, tephra and calcareous nannofossil are utilized to correlate geotectonic events between sedimentary basins. The detailed tephro- and calcareous nannofossil biostratigraphy were established from the upper Miura Group to the lower Kazusaa Group. As results, an erosional surface covered by submarine landslide deposits and pebbly sandstone layers was recognized just below the upper limit of the Mammoth reverse subcronozone (3.2 Ma), which can be recognized as a marker event indicating that the forearc basin was segmented east to west by the growth of local uplift zones. In addition, the tephra beds were correlated between the Chikura and Kazusa groups in the age interval of about 2.3 to 2.0 Ma.

Academic Significance and Societal Importance of the Research Achievements

国内でも最も人口密度が高い地域の一つである南関東の基盤は後期新生代の前弧域で堆積した堆積層から成る.それらの地層は陸上に露出して直接特徴と年代を調査することが可能である.地質学的な時間スケールの堆積速度の変化や構造運動,不整合の形成との関係を明らかにすることで,しばしば大規模な地震被害に見舞われてきた南関東がどのような構造運動の元に発達してきたのかを理解することにつながる.また海底地すべり堆積物の研究から活動的な海底斜面の長期的な安定性を理解する上で知見が得られると期待される.

Report

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

    (6 results)

All 2023 2022 2021 Other

All Journal Article (2 results) (of which Peer Reviewed: 2 results,  Open Access: 1 results) Presentation (3 results) Remarks (1 results)

  • [Journal Article] Basin-wide erosion and segmentation of the Plio-Pleistocene forearc basin in central Japan revealed by tephro- and biostratigraphy2023

    • Author(s)
      Utsunomiya, M., Tamura, I., Nozaki, A., Nakajima, T.
    • Journal Title

      Progress in Earth and Planetary Science

      Volume: in press

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Speciation of extant Umbilicosphaera (Prymnesiophyceae) during the Pliocene2021

    • Author(s)
      Utsunomiya, M., Hagino, K., Tanaka, Y.
    • Journal Title

      Marine Micropaleontology

      Volume: 169 Pages: 102037-102037

    • DOI

      10.1016/j.marmicro.2021.102037

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Presentation] 南関東の前弧海盆の分化と海底地すべり: 鮮新世の指標テフラと生層序による年代制約2022

    • Author(s)
      宇都宮正志・田村糸子・野崎篤・中嶋輝允
    • Organizer
      日本地質学会第129年学術大会
    • Related Report
      2022 Annual Research Report
  • [Presentation] 東京湾周辺の前弧海盆堆積物を繋ぐ鮮新世の指標テフラと海底地すべりによる地層の欠如2022

    • Author(s)
      宇都宮正志,田村糸子,野崎篤
    • Organizer
      Japan Geoscience Union Meeting 2022
    • Related Report
      2021 Research-status Report
  • [Presentation] 微化石・テフラに基づく南関東の前弧海盆堆積物の層序学的実態2021

    • Author(s)
      宇都宮正志
    • Organizer
      日本古生物学会第170回例会
    • Related Report
      2020 Research-status Report
  • [Remarks] Researchmap

    • URL

      https://researchmap.jp/Masa.U

    • Related Report
      2022 Annual Research Report

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Published: 2020-04-28   Modified: 2024-01-30  

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