PHYSICOCHEMICAL FACTORS OF HYPOGENIC ZONING OF HYDROTHERMAL MINERALIZATION DURING ONE- AND MULTI-STAGE INFLOW OF SOLUTIONS

Abstract

The role of physicochemical factors in the natural processes of mineralogenesis during the formation of hypogene zonation of hydrothermal mineralization is analysed. Among them, the temperature of mineral formation (regional and local), acid-alkaline properties of solutions, re-dox potential, stability of mineral-forming complexes, ion activity, and pressure are the most im-portant. All these factors are interconnected and mutually determined. An illustrative example of the effect of temperature on the aggregate state of solutions is the Kariiske gold ore deposit in Eastern Transbaikalia: if the solutions are liquid, then sulphides crystallize, if they are gaseous, then oxides. In this case, we are talking about a one-stage supply of solutions. The processes of ore formation are not only staged, but also cyclical. During the multi-stage inflow of solutions, the values of temperature, pressure, pH, etc. change repeatedly. At each of the stages, directed crystallization of minerals (quartz–silicates–sulphides–carbonates) takes place and the corresponding metasomatosis is manifested – from moderately acidic to moderately alkaline. Different temporal paragenesises are often localized in raised structural blocks that de-veloped according to the keyboard principle. The composition and aggregate state of different time portions of solutions are different, and therefore their mineral products, impurity elements, physicochemical conditions of formation, etc. are different – the whole set of mineralogical and geochemical features is actually based on this. Therefore, physicochemical factors and their change over time and in space are the main rea-son for different mineral, geochemical and thermobarogeochemical zoning of hydrothermal min-eralization. Temperature is the main factor in mineral formation, which acts independently (as a dissolution stimulator) and complexly, since the values of pH, Eh, pressure, activity of elements, etc., depend on its change. Changes in the acid-alkaline properties of solutions are perhaps the most important indicator of post-magmatic mineralization. A change in the redox potential of the environment of mineral formation determines the zonation of ores with metals of variable valen-cy.