[B-PT05] 地球史解読：冥王代から現代まで

[BPT05-02] 南鳥島周辺EEZ南部における高濃度/超高濃度レアアース泥層の分布：主成分・微量元素組成からの示唆

*中村 謙太郎¹、安川 和孝¹、藤永 公一郎¹、加藤 泰浩^1,2,3 (1.東京大学大学院工学系研究科システム創成学専攻、2.東京大学大学院工学系研究科附属エネルギー・資源フロンティアセンター、3.国立研究開発法人海洋研究開発機構)

キーワード：高濃度/超高濃度レアアース泥層、南鳥島EEZ、地球化学

Since the discovery of highly/extremely REY-rich mud layer (more than 2000/6000 ppm ΣREY) within the Japanese Exclusive Economic Zone (EEZ) around the Minamitorishima Island [1], exploitation of REY-rich mud has attracted particular interest because of its high potential as a REY resource. Detailed investigation by subbottom profiling and piston coring conducted over the last three years has revealed the distribution of REY-rich mud (>400 ppm ΣREY) and overlying non-REY-rich sediments within the Minamitorishima EEZ [Nakamura et al., in revision]. However, both lateral and vertical distributions of the highly/extremely REY-rich mud layers are still uncertain. Here we examine major and trace element compositions of deep-sea sediments cored from the Minamitorishima EEZ. On the basis of geochemical characteristics, REY-rich mud can be subdivided into six types including highly/extremely REY-rich mud, and the highly/extremely REY-rich mud layer is the second top layer of the REY-rich mud succession. In the presentation, we discuss the distribution of each layer of the REY-rich mud and its paleoceanographic implication.