Paleoceanography in the marginal seas of the western North Pacific based on siliceous microfossils

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K12222
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Kyushu University
• Principal Investigator: Okazaki Yusuke 九州大学, 理学研究院, 教授 (80426288)
• Co-Investigator(Kenkyū-buntansha): 小野寺 丈尚太郎 国立研究開発法人海洋研究開発機構, 地球環境部門(北極環境変動総合研究センター), 主任研究員 (50467859)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 北太平洋 / 縁海 / 珪質微化石 / 最終氷期 / 海流

Outline of Final Research Achievements

We have investigated siliceous microfossils such as diatoms, radiolarians, and silicoflagellates in sediment samples from the East China Sea, Japan Sea, Sea of Okhotsk, and Bering Sea. Our study on paleoceanographic changes for the past 20 kyrs since the last glacial maximum suggests that(1) surface water change from the Chinese coastal water to the Kuroshio water in the northern East China Sea; (2) annual mean surface water temperature in the southern Japan Sea was ~4 degree C, comparable to the present Sea of Okhotsk; and (3) to prepare a catalog of silicoflagellates in the North Pacific surface sediments.

Free Research Field

古海洋学

Academic Significance and Societal Importance of the Research Achievements

わたしたちが暮らす日本列島の気候や風土がどのような環境変動を経て成立したか、2万年前の最終氷期最盛期における日本海古水温復元に初めて成功し、日本海への対馬暖流に流入タイミングを新たに成約した。大陸氷床消長にともなう海水準変動によって日本列島周辺域の海流が大きく変化し、現在の日本列島の気候が成立していった様子について新たな知見を得た。