Hydrothermal Formations on the Pervenets Rise, Japan Sea

Abstract

This paper provides information on the structure, chemical composition, and concentrations of microelements in ferromanganese crusts and siliceous crusts sampled on the Pervenets Rise, Sea of Japan. The crusts were formed by cementation of small fragments of green clays (celadonite) by manganese hydroxides (todorokite and birnessite) or by silica. The primary process involved the generation of celadonite, which was deposited as ore-bearing hydrothermal brine that was discharged in the caldera of the volcano or on its slopes. The crusts have a structure that indicates their formation during diffuse percolation of gas-charged hydrothermal brine along fissures or weakened zones in volcanic rocks and subsequent cementation of the resulting celadonite deposits with manganese or siliceous oxides. The manganese and the siliceous mineralization are separated over time, as well as, frequently, in space, and are more local.