FERROMANGANESE DEPOSITS IN THE ASHADZE-1 HYDROTHERMAL FIELD (MID-ATLANTIC RIDGE, 12°58′ N)

Abstract

Subaqueous ferromanganese deposits (FMD), except nodules, are commonly classified into hydrogenic and hydrothermal types. Both types are formed as a result of coprecipitation of Fe–Mn colloids that absorb chemical elements, including nonferrous metals (NFM), from seawater. It is assumed that the hydrothermal deposits should be depleted in NFM relative to the hydrogenic counterparts, because the duration of contact of colloids, which produce the hydrothermal deposits, with seawater is much shorter.