Spatiotemporal paleoclimate transition in East Asia during Cretaceous

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K03787
• 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): 2018-04-01 – 2023-03-31
• Keywords: 古気候 / 東南アジア / 白亜紀

Outline of Final Research Achievements

In this study, we clarified the spatiotemporal changes in the ancient climate of Southeast Asia during the Cretaceous period. The specific survey areas were four locations: Yenchau, northern Vietnam (near 20°N); Nha Trang, central-southern Vietnam (near 15°N); Phu Khoq, southern Vietnam (near 10°N); and Kuching, Malaysia (near the equator). In the Early Cretaceous, all survey areas had an ancient climate equivalent to the tropical rainforest climate zone. However, during the mid-Cretaceous extreme warming period, extreme drought was detected at 20°N and moderate drought at around 15°N. From these results, it was revealed that extreme warming causes aridification in low-latitude regions, and the extent of this phenomenon was successfully identified.

Free Research Field

地質学

Academic Significance and Societal Importance of the Research Achievements

東南アジアが白亜紀中期に砂漠化した証拠は先行研究でも示されてきた．しかし先行研究は内陸域において実施されたものなので，内陸性気候特有のローカルな気候変化にすぎない可能性を否定できなかった．今回の研究では，全て沿岸域を研究対象として選定している．したがって，本結果は全球的な気候変動の表れであることが示された．また，白亜紀中期は温暖化が進行した代表的な地質時代であり，近未来，人類と地球が直面するであろう環境変動の予測に役立つ研究対象である．本研究では，温暖化が東南アジア低緯度地域の乾燥化を引き起こすことを示唆した．したがって，近未来，同様の環境変動が発動されうることが示唆された．