Studying Evolutionary Processes of Petergan Playa Brines in South Khorasan, East of Iran

The Petergan Playa lies in east of Iran, covering an area of 212.5 km2. The playa is located 135 km from the city of Qayen at the border area known as Shahrakht. Thus, in the present study, to study the brines and their evolution, sampling was conducted from some of 95 brines based on an ordered network. The brines were analyzed using the Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) method. The cations found in the brines showed abundance in the amounts of Na^+,Ca^(2+), Mg^(2+),〖and K〗^+.For the anions an abundance was observed in the amounts of Cl^-, SO_4^(2-), and HCO_3^-. The type of brines was as follows: Na^+-SO_4^(2-)-Cl^- , by pondering fairly neutral acidity and chemical investigation of the ingress waters, it can be inferred that, the waters are of Ca^(2+)>CO_3^(2-), Cl^-+ SO_4^(2-)>HCO_3^-,HCO_3^-≪Ca^(2+)+ Mg^(2+) molar ratios, following the geochemical route П in the brines’ geochemical evolution diagram, which is similar to the brines in Saline Valley and the Dead Valley in the United States. X-Ray Diffraction (XRD) results revealed that, the most abundant minerals in the brines are Quartz, Gypsum, Halite, and Calcite. Accordingly, source of the brines would be meteoric waters as well as neutral waters and brines with hydrothermal source.