PHYSICOCHEMICAL FOUNDATIONS OF HYDROGEOCH EMICAL AND HYDROTHERMAL PROCESSES

The regularities of variation of equilibrium constants and reaction ra tes of predominant physico-chemical processes determining the water/ro ck system state as well as element behavior in hydrogeochemical and hy drothermal processes is considered. Redox and complex forming processe s are goverming the chemical behavior of elements in the aqueous phase defining local equilibrium Eh and pH values of the aqueous solution. The processes of dissolution, adsorption and ionic exchange are sugges ted to determine the water/rock heterogeneous system state thus the ch emical behavior of elements forming the solid and gaseous phases. ff t he aqueous fluid flux rate in relation to that of other phases is belo w the mass exchange reaction rate, the water/ rock system should be co nsidered as a system near to the local equilibrium.