CHEMICAL CHARACTERISTICS (COMPOSITION, PH , AND EH) OF A ROCK-WATER SYSTEM .1. THE GRANITOIDS-WATER SYSTEM

Computer modeling was used to study interactions in a rock-water syste m for T ranging from 25 degrees C to the temperature of liquidus for e ach type of rocks and for P from 0.001 to 5 kbar. The results presente d in this paper were obtained by modeling the equilibrium of water wit h rocks of granitoid composition (granite, syenite), containing either no Cl, S, and C, or their clarke concentrations for these rocks. It i s shown that background concentrations of S and C in granite are suffi cient for them to act as the potential-controllers for these component s in the formation of redox conditions in the rock-water system. When S and C are present in granite in concentrations lower than clarke, an d in syenite, in clarke concentrations, the redox potential of the gra nitoids-water system is controlled by buffer redox-reactions of iron. On the whole for all the examined T and P, the liquid phase of the gra nitoids-water system has an alkaline and reducing effect relative to t he characteristics of pure water.