A Comparison of Hydrogeochemistry and Brines evolution in Meyghan and Hoz-e-Soltan Playas

This research is focused on study of hydrogeochemistry and brines evolution of Mighan and Hoz-e-Soltan Playas, based on studying brines and hydrogeochemistry evidences. Meyghan and Hoz-e-Soltan Playas as an intra-continental sedimentary basins, are located in Qom watershed, in central part of Iran. Both Playas are influenced by the volume of input groundwater, intermittent streams, precipitation and evaporation. In order to study the brines and their evolution process, 19 and 25 water samples were taken from center of Playas to the margins, respectively by digging holes. Physico-chemical parameters were measured in the site and geochemical analysis of brines was performed in laboratory. In addition, 95 and 109 sediment samples were collected from Meighan and Hoz-e-Soltan playas, respectively by hand auger and their mineralogy and sedimentary characters were analyzed. Major cations of both Playas are Sodium, Chloride and Sulfate; dominant evaporative minerals are Calcite, Gypsum, Halite, Thernadite and Polyhalite. Hydrochemical studies of inlet waters of both Playas indicate that mole ratio is HCO3