日本地球惑星科学連合2018年大会

講演情報

[JJ] Eveningポスター発表

セッション記号 S (固体地球科学) » S-CG 固体地球科学複合領域・一般

[S-CG61] 海洋底地球科学

2018年5月23日(水) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:沖野 郷子(東京大学大気海洋研究所)

[SCG61-P15] Characterization of nuclei of ferromanganese nodules in the Minamitorishima EEZ using X-ray CT

*下村 遼1中村 謙太郎1町田 嗣樹2,3安川 和孝1,2藤永 公一郎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.海洋研究開発機構)

キーワード:マンガンノジュール、X線CT分析、南鳥島EEZ

It is well known that ferromanganese nodules start to grow around nuclei. Thus, characterizing the nuclei of the nodules can provide important information on the conditions for the growth initiation of the nodules. However, detailed investigation on nuclei of ferromanganese nodules has so far been scarce.
In this study, X-ray CT is used as a method to analyze nondestructively the nuclei of ferromanganese nodules. Due to the difference in the shape and the X - ray absorption rate, we classified the nuclei of the nodules into 4 types: nucleus I, nucleus II, nucleus III, and nucleus IV. Comparison with XRF mapping analysis and ICP-MS measurement of the nuclei revealed that nucleus I (showing a low X-ray absorption rate and exhibiting lumpy shape) corresponds to consolidated pelagic clay. We also identified silica, fish teeth, phosphorite, basalt and ironstone. In addition, based on the identification of nuclei by X-ray CT analysis, it is revealed that the majority of the nuclei of the nodules in the Minamitorishima EEZ is consolidated pelagic clay (“nucleus I”).
In the presentation, we will discuss the origin of the nuclei of ferromanganese nodules and its relation to the growth initiation of the nodules in the Minamitorishima EEZ.