Method of exploitation, selection of mine site and design of mining system of cobalt-rich manganese deposits on seamounts would be greatly influenced by the distribution characteristics as well as the associated seabed features, such as the seabed topography, surface morphology and sediment characteristics. An example detailed analysis of the distribution characteristics of crusts, nodules and sediments on a seamount is introduced. On the basis of the results, a case study of their influences on the mining system is presented.


Cobalt-rich manganese deposits on Pacific seamounts are being viewed as potential reserve for strategic metal elements, such as cobalt, nickel, platinum, etc., besides manganese and iron, as they occur at relatively shallower depths and closer to the coast than deep-sea manganese nodules (Halbach and Manheim, 1984; Manheim, 1986). Several research groups have reported the distribution of cobalt-rich manganese deposits in various areas (Halbach et aI., 1982; Cronan, 1984; Hein et aI., 1985a, b; Pichocki and Hoffert, 1987; Misawa et aI., 1987; Yamazaki et aI., 1994b). Some studies have also attempted to evolve methods for their resource evaluation (Clark, 1985; Hawaii, 1987; Morgan et aI., 1988; Cronan et aI., 1991; Yamazaki et aI., 1992; Yamazaki, 1993; Yamazaki et aI., 1994a). Miner concepts only for the crust type deposits were proposed (Halkyard, 1985; Yamazaki et aI., 1995a). Influence of distribution characteristics of crusts, nodules and sediments and their morphological features, on method of the exploitation, selection of the mine site, as well as design of the suitable mining system is described. METHODS Results from a deep-tow survey with stereo cameras and video camera in an edge area of the seamount top during the R/V Hakurei-maru No.2 cruise, have been analyzed to characterize the distribution and association with the different seabed features.

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