| Project/Area Number |
21H01169
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 17030:Human geosciences-related
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| Research Institution | Nagoya University |
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Principal Investigator |
Humblet Marc 名古屋大学, 環境学研究科, 准教授 (40623616)
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| Co-Investigator(Kenkyū-buntansha) |
井龍 康文 東北大学, 理学研究科, 教授 (00250671)
藤田 和彦 琉球大学, 理学部, 教授 (00343377)
横山 祐典 東京大学, 大気海洋研究所, 教授 (10359648)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥18,200,000 (Direct Cost: ¥14,000,000、Indirect Cost: ¥4,200,000)
Fiscal Year 2023: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2022: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
Fiscal Year 2021: ¥14,300,000 (Direct Cost: ¥11,000,000、Indirect Cost: ¥3,300,000)
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| Keywords | Coral reef / Sea level change / Climate change / Quaternary / Minatogawa Formation / Ryukyu Islands / Okinawa / Limestone / Sea-level change |
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| Outline of Research at the Start |
Information on Earth’s geological history contained in sediments and rocks is key to understand the past, present, and future evolution of our planet. Fossil coral reefs in particular are treasure troves of information concerning climate and sea-level changes because their growth is constrained by sea level and sea surface temperature. In this project, we will study fossil reef deposits in southern Okinawa to constrain the timing and amplitude of sea-level change during the Quaternary and investigate how coral reef ecosystems responded to these perturbations.
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| Outline of Final Research Achievements |
The Minatogawa Formation in Okinawa-jima represents a unique late Middle to Late Pleistocene record of carbonate sedimentation consisting of well-sorted foraminiferal grainstones and coral-rich limestones. This formation yields important information on Quaternary sea-level and reef growth history. In this study, we have recovered 188 m of core sections from twelve boreholes drilled into the Minatogawa Formation in southern Okinawa-jima. In order to record lateral variations in sedimentary facies, we have drilled along two transects about 1 km apart and perpendicular to the shoreline. Six boreholes (Hole 1-6) were drilled along the first transect and five (Hole 1b-5b) along the second. One borehole (Hole C) was drilled between the two transects. The older Pleistocene basement (Naha Formation) underlying the Minatogawa Formation was reached in all but one hole. The thickness of the Minatogawa Formation ranges from 0 m in the most inland holes to 24 m closer to the shoreline.
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| Academic Significance and Societal Importance of the Research Achievements |
The cores from the Minatogawa Formation provide a unique window into the late Middle to Late Pleistocene sea-level and reef growth history in the Northwest Pacific. This time window is particularly important to study rapid environmental changes and their impact on coral reef ecosystems.
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