Examination of the weathering hypothesis as a triggering cause of the Cretaceous OAEs

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03728
• 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: Waseda University
• Principal Investigator: Ohta Tohru 早稲田大学, 教育・総合科学学術院, 教授 (40409610)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 海洋無酸素事変 / 白亜紀 / 蝦夷層群 / 風化作用

Outline of Final Research Achievements

The ocean anoxia events (OAEs) that occurred in the Cretaceous period are an important research subject for understanding the Earth system in greenhouse periods. In this research, we verified the reality and impact of the "weathering hypothesis," which is attracting attention as a triggering factor for OAEs. As a result, it is known that ocean anoxia was caused during periods of extreme warming, but it became clear that the increased weathering of the continental crust is deeply involved in this phenomenon. Especially, the results of this time were detected not in a closed regional research case, but along the Pacific Ocean, which is a large ocean, suggesting a global climate change response associated with warming.

Free Research Field

堆積学

Academic Significance and Societal Importance of the Research Achievements

地球温暖化は様々な社会的・環境的・生態的な影響を及ぼすことが知られている．温暖化の影響としてあまり注目されていない応答として，大陸地殻の風化作用増大があげられる．風化作用の増大は海洋に流出する栄養塩を増加させる効果があり，これが一次生産性の増大と海洋中の溶存酸素の欠乏を招くことになる．この結果，海洋環境と生態系の悪化を招くことになるが，本研究ではこのシナリオが過去の地球温暖期に発動したことを明らかにした．したがって，本研究は温暖化が進行している近未来に発動し得るもう一つの環境摂動の警鐘となる．