Reconstruction of late Quaternary sea-level and reef growth history in the Ryukyu Islands

琉球群岛晚第四纪海平面及礁体生长历史重建

• 批准号: 21H01169
• 负责人: HUMBLET Marc
• 金额: $ 11.65万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2021
• 资助国家: 日本
• 起止时间: 2021-04-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-21H01169/
• 关键词: Coral reef; Sea level change; Climate change; Quaternary; Okinawa; Sea-level change

Five boreholes (10-27 m in length) were drilled into late Middle Pleistocene limestone (Minatogawa Formation) along a transect perpendicular to shore in southern Okinawa Island in December 2022 and January 2022. The total cored length is 90 m. After shipping the cores to the Kochi Core Center for safe storage, each core was X-ray CT-scanned. The cores were then split in half, photographed, and their lithology, sedimentary structures, and major fossil biotic components, particularly corals, coralline algae, and foraminifers, were carefully described in September 2022. Seven additional boreholes (8-23 m in length) were drilled in the same geological formation in August and September 2022. The total cored length is 98 m. Five of these boreholes were drilled along a second transect perpendicular to shore situated 800 m to the south-west of the first transect. One borehole was drilled between the first and second transect, and another borehole was drilled along the first transect. The seven new cores were shipped to the Kochi Core Center for storage in January 2023. Sampling of the cores of the first transect was conducted at the Kochi Core Center in February 2023 for sedimentological analysis, radiometric dating, taxonomic identification of corals, crustose coralline algae, and foraminifers, as well as elemental and stable isotope geochemistry. In addition, the corals observed in the cores of the first transect were identified at the lower taxonomic level possible and their status (in situ vs. not in situ) duly noted. The thickness of coralline algal crust was also recorded.

2022年12月和2022年1月，将五个孔（长度为10-27 m）钻入沿冲绳岛南部的沿沿岸垂直于海岸的横断面的中期更新世的石灰石（Minatogawa组）。将核心运送到高知核心中心以进行安全存储后，每个核心将被X射线CT扫描。然后将核心分成两半，拍照，其岩性，沉积结构以及主要的化石生物成分，尤其是珊瑚，珊瑚藻类和有孔虫，在2022年9月进行了仔细描述。在8月和2022222222222年8月和9月98日，在8月和9月98日的8月，七个井眼（8-23 m的长度）进行了钻孔。这些钻孔中的五个沿垂直于沿岸的第二个横切钻至，位于第一个横除的西南800 m。在第一个和第二个横切之间钻了一个钻孔，另一个钻孔沿着第一个样带钻了一个钻孔。这七个新核心于2023年1月运往高知核心储存中心。第一个横切核心的取样是在2023年2月在高知核心中心进行的沉积学分析，辐射测定，分类学，核心，甲壳岩岩层藻类藻类和有孔的元素和元素和e元和St.此外，在较低的分类学水平上鉴定出在第一个横除的岩心中观察到的岩体，其状态（原位与非原位）的状态得到了正式指出。还记录了冠状藻壳的厚度。