Initial stage of the hydrothermal ore accumulation within the field at 9°50′ N on the East Pacific Rise

In 2003, several hydrothermal mounds located at 9°50′ N on the East Pacific Rise were described and sampled during the expedition of R/V Akademik Mstislav Keldysh during dives of Mir deep-sea manned submersibles. These hydrothermal mounds were formed during a few recent years after the volcanic activity in this region that occurred in 1991. The studies of the chemical and mineralogical compositions of the hydrothermal deposits of these mounds and of the chemical composition of the principal sulfide minerals helped to describe the initial stage of the formation of the hydrothermal circulation system and the initiation of the hydrothermal ore formation.