日本地球惑星科学連合2019年大会

講演情報

[J] ポスター発表

セッション記号 M (領域外・複数領域) » M-GI 地球科学一般・情報地球科学

[M-GI34] 海底マンガン鉱床の環境,開発,地球史

2019年5月28日(火) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:臼井 朗(高知大学海洋コア総合研究センター)、高橋 嘉夫(東京大学大学院理学系研究科地球惑星科学専攻)、鈴木 勝彦(国立研究開発法人海洋研究開発機構・海底資源研究開発センター)、伊藤 孝(茨城大学教育学部)

[MGI34-P03] Geochemical characteristics of the nuclei of ferromanganese nodules in the Minamitorishima EEZ

*寺内 大貴1中村 謙太郎1下村 遼1堀之内 航一1安川 和孝1,2町田 嗣樹2,1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、2.千葉工業大学次世代海洋資源研究センター、3.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)

キーワード:鉄・マンガンノジュール、核、固結した遠洋性粘土、化学組成、南鳥島EEZ

Ferromanganese nodules are polymetallic concretion mainly composed of Mn- and Fe-oxyhydroxides with significant concentrations of valuable metals such as Ni, Cu and Co [1, 2]. The nodules can be found on deep-sea sediments worldwide, and their dense distribution has recently been discovered in the Japanese exclusive economic zone (EEZ) around Minamitorishima Island [3, 4].



It is well known that almost all ferromanganese nodules have nuclei, which clearly indicates that growth of a nodule generally starts on nucleus surface. Characterizing the nuclei of the nodules can, thus, provide important information on the conditions for the growth initiation of the nodules. Previous study [5] revealed that the nuclei of the nodules in the Minamitorishima EEZ can be classified into four types (nucleus I ~ IV), and that the majority of the nuclei is consolidated pelagic clay (nucleus I). However, detailed chemical characteristics of the nucleus I, as well as those of the other types of nuclei, have not yet been fully understood.



Here, we performed major and trace element analysis of the nuclei (especially of the nucleus I) in order to reveal their chemical features. In the presentation, we will show the results of the chemical characterization of the nuclei and then will discuss the origin of the nuclei of ferromanganese nodules in the Minamitorishima EEZ.





References
[1] Petersen et al. (2016) Marine Policy, 70, 175–187, [2] Hein et al. (2013) Ore Geology Reviews, 51, 1–14, [3] Machida et al. (2016) Geochemical Journal, 50, 539–555, [4] JAMSTEC press release, August 26, 2016, [5] Shimomura et al. (2018) JpGU meeting 2018.