Volcanogenic Sedimentary Deposits

mineral deposits occurring in cases of the entry into ancient and modern sea and ocean basins of mineral products formed during volcanic eruptions on the sea floor, on islands, and along the shores and upon the precipitation of these products in the form of strata and nodules. The mineral products entered the areas of sedimentary accumulation in solutions of volcanic gases and hot waters of volcanic origin, in a state of adsorption on the surface of volcanic ash, or upon decomposition of cooled lavas and ash by sea water as a result of their leaching and removal from lava and ash by volcanic gaseous and liquid solutions.

Volcanogenic sedimentary deposits include large stratified deposits of iron and manganese ores composed of silicates, carbonates, oxides, and hydroxides of the above metals, as well as pyrite ores containing sulfide compounds of iron, copper, and zinc and occasionally lead, barite, and gypsum. Certain investigators believe that some phosphorite and bauxite deposits are also volcanogenic sedimentary deposits. They are deposited in layers of rock consisting of lavas, ash, and strata of siliceous rocks alternating with normal marine deposits. Accumulations of nodular iron and manganese ores, which are found on the bottom of the Pacific, Atlantic, and Indian oceans and contain admixtures of cobalt, nickel, molybdenum, and other valuable metals, may also have been produced as a result of submarine eruptions of young volcanoes. Volcanogenic sedimentary deposits of ancient and modern geological periods are known.