| 研究実績の概要 |
During FY 2022 research activities related to Grant-in-Aid for Scientific Research (C) project number 18K03824 were focused on two specific research themes: (1) the study of coral reef growth history at intermediate to mesophotic depths in the Great Barrier Reef of Australia since the end of the Last Glacial period, and (2) the study of the late Middle Pleistocene of the Minatogawa Formation in southern Okinawa Island. To address the first theme, the cores from two boreholes (M0040A and M0041A) drilled during IODP Expedition 325 were studied and the results presented in a manuscript finalized and submitted in 2022, and published now in the Special Publication 49 of the International Association of sedimentologists. This paper explores reef growth history at palaeo-water depths >20 m over a time period spanning the last 30,000 years. Palaeo-water depth interpretation of litho- and biofacies indicates palaeo-water depths ranging from 10 to 130 m. Reef ecosystems dominated by microbialite and corals developed at intermediate and mesophotic depths during the transition from MIS 3 to MIS 1 with maximum vertical accretion rates of 2 to 5 mm yr-1, depending on the calculation method. For the second research theme, focused on the late Middle Pleistocene of the Minatogawa Formation in southern Okinawa Island, data on the sedimentology and fossil content of limestones cropping out in Horikawa quarry (26°07’42” N, 127°45’54” E) acquired over the past few years are being compiled and summarized in a manuscript that will be submitted for publication during FY 2023.
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