[B-PT23] 地球史解読：冥王代から現代まで

★ [BPT23-22] サブボトムプロファイラによる深海堆積物の解析とその南鳥島EEZにおけるレアアース泥分布への示唆

*中村 謙太郎¹、町田 嗣樹²、正木 裕香³、沖野 郷子⁴、飯島 耕一³、鈴木 勝彦³、加藤 泰浩¹、KR13-02 乗船者一同 ³、MR13-E02 Leg2 乗船者一同 ³、KR14-02 乗船者一同 ³、MR14-E02 乗船者一同 ³ (1.東京大学工学系研究科、2.早稲田大学、3.海洋研究開発機構、4.東京大学大気海洋研究所)

Subbottom profiling was conducted in the Japanese Exclusive Economic Zone (EEZ) around Minamitorishima Island to reveal the distribution of REY-rich mud in the Minamitorishima EEZ. Based on the shape and pattern of the reflectors, three discrete acoustic facies of opaque (O) type, transparent (T) type, and layered (L) type were distinguished. Distribution of the O-type facies is restricted to just on or immediate vicinity of seamounts, suggesting that this acaustic facies corresponds to rocky outcrop without soft sediment cover. The T-type facies occurs in northern part and southern to southeastern part of the Minamitorishima EEZ, whereas the L-type facies widely covers central part of the area. By comparing the sub-bottom profiler record with sediment core samples obtained by piston coring shows that the acoustic facies T corresponds to REY-rich mud, whereas acoustic facies L corresponds to non-REY-rich terrigenous sediment.