PHYSICOCHEMICAL MODELING OF THERMODYNAMIC EQUILIBRIA IN A CARBONATE-EVAPORITE SEDIMENTARY-ROCKS WATER-HYDROCARBONS SYSTEM DURING CONTACT-METAMORPHISM AND CATAGENESIS

Interactions in the hydrocarbons-water-sulfate-carbonate substrate mul tisystem upon heating it by trap intrusives at 100-700 degrees C are c onsidered. Possible reactions are calculated for various contents of t he initial chemical compounds. Sulfates and carbonates decompose to fo rm considerable amounts of hydrogen sulfide and carbon dioxide, respec tively. Mercaptans appear among hydrocarbons. Increasing the temperatu re leads to a growth of calcitization of sediments and, at temperature s above 500 degrees C, dolomite completely decomposes. The model is ap propriate for the sedimentary basins with flood magmatism and sulfate- carbonate sedimentation.