Hydrogeochemical modeling and dedolomitization processes in the Patagonian Boulders and Patagonia Formation in the eastern Patagonia, Argentina

The aim of this study was to contribute to the understanding of the hydrogeological system of the Argentine Patagonia Extra-Andina region, focused on the Atlantic coastal area at 46° south latitude. The hydrogeochemical aspects of this aquifer system were taken into consideration for this purpose. The database includes 193 chemical analyses of major ions obtained through standard laboratory methods. A statistical analysis of the data, as well as the realization of hydrochemical models using PHREEQC software, was performed. The regional groundwater flows from west to east, with the recharge water being a sodium–chloride–bicarbonate type, and the discharge of water is typified as a sodium–sulfate–chloride type. The hydrogeochemical evolution of the aquifer shows a general augmentation of salinity and major ions in the groundwater-flow path, except for HCO 3 − . Inverse hydrochemical modeling showed that gypsum dissolution with calcite precipitation, Ca 2+ /Na + and Mg 2+ /Na + ionic exchange, and dedolomitization are the main processes along the groundwater flow pathway.