[M-ZZ41] Marine manganese deposits: from basic to applied sciences

[MZZ41-06] Factors controlling the distribution of ferromanganese nodules in the Minamitorishima EEZ

*Kentaro Nakamura¹, Ryo Shimomura¹, Koichi Horinouchi¹, Shiki Machida^2,3, Kazutaka Yasukawa^1,2, Koichiro Fujinaga^2,1, Yasuhiro Kato^1,2,3 (1.Department of Systems Innovation, School of Engineering, University of Tokyo, 2.ORCeNG, Chiba Institute of Technology, 3.JAMSTEC)

Keywords:ferromanganese nodules, Minamitorishima EEZ, distribution, underlying sediments, deep-sea currents

Ferromanganese nodules are polymetallic concretions consisting mainly of manganese and iron, which are found in deep-sea surficial sediments in many areas of the world ocean [1]. Since 1960s, the nodules are of high economic interest due to their enrichment of valuable metals such as Ni, Cu, and Co [2]. Very recently, large-scale distribution of ferromanganese nodules has also been confirmed within Japanese exclusive economic zone (EEZ) around Minamitorishima island [3, 4] and, for future exploitation of the nodules in the Minamitorishima EEZ, detailed investigation to elucidate the origin and distribution of the nodules is needed.

Ferromanganese nodules have long been studied extensively, especially those occurring between the Clarion and Clipperton fracture zones [5]. However, many important questions still remain unanswered regarding the formation and distribution of the nodules. In particular, factors controlling the distribution of ferromanganese nodules have been one of the most important problems to solve. Correlation between nodule distribution and deep-sea currents has long been pointed out in the southern Pacific and southern Indian Oceans [6, 7]. Moreover, it has been considered that hiatus of the underlying sediments, caused by deep-sea currents, is also related to the occurrence of ferromanganese nodules [6, 8].

In this presentation, we will discuss the factors controlling the distribution of ferromanganese nodules in the Minamitorishima EEZ in relation to underlying sediments and deep-sea currents.

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] ISA (2012) Briefing Paper 01/12, [6] Kennett and Watkins (1975) Science, 188, 1011–1013, [7] Wright et al. (2005) New Zealand Journal of Geology and Geophysics, 48, 27–41, [8] Usui et al. (1987) Marine Geology, 74, 237–275.