Development of the age model for the Pleistocene around the Northwestern Pacific region

• Project/Area Number: 18K03771
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: Chiba University
• Principal Investigator: Kameo Koji 千葉大学, 大学院理学研究院, 准教授 (00312968)
• Co-Investigator(Kenkyū-buntansha): 林 広樹 島根大学, 学術研究院環境システム科学系, 准教授 (80399360) ; 久保田 好美 独立行政法人国立科学博物館, 地学研究部, 研究員 (80710946)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2018: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 年代モデル / 更新世 / 石灰質ナノ化石 / 浮遊性有孔虫 / 酸素同位体曲線 / 前期更新世 / 上総層群 / 黄和田層 / 太田代層 / 梅ヶ瀬層 / 複合年代尺度 / 北西太平洋 / 浮遊性有孔虫化石 / 酸素同位体

Outline of Final Research Achievements

This study investigated calcareous microfossils and oxygen isotopes of foraminifera of the Kazusa Group in the Boso Peninsula, Japan, to establish an age model around the northwestern Pacific region. A high-resolution age model from ca. 1100 to 700 kyrs was firstly constructed based on oxygen isotope stratigraphy of planktonic and benthic foraminifera. Quaternary biohorizons of calcareous nannofossils were evaluated in comparison with the age model and new bioevents were found. The age model constructed by this study can be applicable to clarify geologic ages of formations and understand paleoceanographic changes around the northwestern Pacific.

Academic Significance and Societal Importance of the Research Achievements

本研究で構築した新しい年代モデルは，とくにこれまでデータの空白地域であった北西太平洋海域の更新世における地球科学的研究を行う上で，重要な年代学的基盤となる．また，評価された石灰質微化石の基準面は，最新の年代が付けられることとなった．この年代モデルはこれまでよりも詳細な年代決定を可能にするため，様々な地域の地層の年代決定に適用されることにより，地層の形成過程をこれまでよりも詳しく復元することが可能になる．

Research Products

• [Journal Article] Formal ratification of the Global Boundary Stratotype Section and Point (GSSP) for the Chibanian Stage and Middle Pleistocene Subseries of the Quaternary System: the Chiba Section, Japan (2021)
  • Author(s): 3.Suganuma, Y., Okada, M., Head, M.J., Kameo, K., Haneda, Y., Hayashi, H., Irizuki, T., Itaki, T., Izumi, K., Kubota, Y., Nakazato, H., Nishida, N., Okuda, M., Satoguchi, Y., Simon, Q., Takeshita, Y
  • Journal Title: Episodes Volume: -
  • Peer Reviewed / Open Access
• [Journal Article] Calcareous nannofossil biostratigraphy of the Lower?Middle Pleistocene boundary of the GSSP, Chiba composite section in the Kokumoto Formation, Kazusa Group, central Japan, and implications for sea-surface environmental changes (2020)
  • Author(s): Kameo Koji、Kubota Yoshimi、Haneda Yuki、Suganuma Yusuke、Okada Makoto
  • Journal Title: Progress in Earth and Planetary Science Volume: 7 Issue: 1
  • DOI: 10.1186/s40645-020-00355-x
  • Peer Reviewed / Open Access
• [Presentation] Morphologic change of a calcareous nannofossil species, Coccolithus pelagicus (Wallich) Schiller, during the Quaternary (2020)
  • Author(s): Kuwano, D., Suzuki, K. and Kameo, K.
  • Organizer: The Micropaleontological Society 50th Anniversary Conference 2020
  • Int'l Joint Research
• [Presentation] Orbital-scale paleoceanographic changes around the Pacific side of Japan in Early Pleistocene based on calcareous nannofossil records (2020)
  • Author(s): 4.Kuwano, D., Kameo, K., Kubota, Y., Mantoku, K., Utsunomiya, M. and Okada, M.
  • Organizer: JpGU-AGU Joint Meeting 2020
• [Presentation] 上総層群黄和田層上部の石灰質ナノ化石層序と推定される海洋環境の変化 (2018)
  • Author(s): 桑野太輔・亀尾浩司
  • Organizer: 日本地球惑星科学連合2018年大会
  • Int'l Joint Research
• [Presentation] 房総半島および銚子地域に分布する下部更新統の石灰質ナノ化石群集と推定される海洋表層環境 (2018)
  • Author(s): 椙﨑翔太・亀尾浩司
  • Organizer: 日本地球惑星科学連合2018年大会
  • Int'l Joint Research