[MZZ41-P05] Geochemical features of ferromanganese nodules in the Minamitorishima EEZ
Keywords:ferromanganese nodule, Deep-ocean mineral resources, Minamitorishima EEZ, critical metals, bulk chemical anaylsis
In 2010, a dense field of Fe-Mn nodules was discovered for the first time on a small seamount approximately 300 km east of Minamitorishima Island, in the Japanese Exclusive Economic Zone (EEZ) . Collected Fe-Mn samples are structurally and compositionally similar to Fe-Mn crusts in the Minamitorishima EEZ, suggesting that they originated from hydrogenetic precipitation of Fe-Mn-(oxyhydr)oxides .
In 2016, to investigate the distribution and variation in chemical composition of Fe-Mn nodules in the Minamitorishima EEZ, the cruise YK16-01 of R/V Yokosuka was conducted. During this cruise, we discovered several areas where Fe-Mn nodules were densely distributed in the eastern to southeastern part of the Minamitorishima EEZ. We collected Fe-Mn nodule samples by seven dives of the Shinkai 6500 in the eastern to southern parts of the Minamitorishima EEZ.
In this study, major and trace element analyses of collected samples have been performed to understand geochemical features, and the origin of Fe-Mn nodules in the Minamitorishima EEZ. In the presentation, we will discuss the cause of the variation in geochemical features and its implication for the growth process of the Fe-Mn nodules.
 Machida, S. et al. (2016) "Geology and geochemistry of ferromanganese nodules in the Japanese Exclusive Economic Zone around Minamitorishima Island." Geochemical Journal 50, 539-555.