[S-CG56] 海洋底地球科学

[SCG56-09] 南鳥島EEZの拓洋第5海山東方海域におけるレアアース泥の地球化学的特徴と分布状況

*藤永 公一郎^1,2、安川 和孝^3,1、野崎 達生^4,2,1,5、町田 嗣樹^1,2、高谷 雄太郎^6,2,1、大田 隼一郎^1,2、矢野 萌生³、下村 遼³、田中 えりか³、見邨 和英³、堀之内 航一³、松本 賢治³、臼井 洋一⁴、山本 浩文⁴、中村 謙太郎³、加藤 泰浩^2,3,1、KM17-14C航海 乗船者一同 (1.千葉工業大学 次世代海洋資源研究センター、2.東京大学 大学院工学系研究科 エネルギー・資源フロンティアセンター、3.東京大学 大学院工学系研究科 システム創成学専攻、4.海洋研究開発機構、5.神戸大学 大学院理学研究科 惑星学専攻、6.早稲田大学 創造理工学部 環境資源工学科)

キーワード：レアアース、レアアース泥、深海堆積物、南鳥島、海底鉱物資源

In 2013, we discovered deep-sea sediment containing 400 – 8,000 ppm of total rare-earth elements and yttrium (REY), which was termed “REY-rich mud”, within the Japanese exclusive economic zone (EEZ) around the Minamitorishima Island (Kato et al., 2013; Iijima et al., 2016; Fujinaga et al., 2016; Ohta et al., 2016; Nakamura et al., 2016; Takaya et al., 2018; Yasukawa et al., 2018). To clarify the mineralogical/chemical characteristics and distribution of the REY-rich mud in the Minamitorishima EEZ, we conducted nine research cruises over five years. During the KM17-14C cruise by R/V KAIMEI from December 16th, 2017 to January 7th, 2018, we investigated the distribution of the REY-rich mud in the eastern off the Takuyo-Daigo Seamount within the Minamitorishima EEZ, one of the most promising areas for REY-rich mud development. We collected five sediment cores by piston/gravity coring, and implemented bulk chemical analyses by using inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) for trace and rare-earth elements, and X-ray fluorescence (XRF) for major elements. In this presentation, we report the sedimentological and geochemical features of the deep-sea sediments including REY-rich mud, and discuss the distribution of the REY-rich mud in the eastern off the Takuyo-Daigo Seamount.