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 km^2. The playa is located 135 km from the city of Qayen, South Khorasan Province, Iran at the border area known as Shahrakht. Some parts of the playa have stretched into Afghanistan. Thus, the present research was conducted to study the brines and their evolution, sampling was done from some of 95 brines based on an ordered network, and their location was spotted by the GPS. Depth and status of sampling were also recorded. The brines were analyzed using the Inductively Coupled Plasma–Mass Spectrometry (ICP–MS) method. The cations found in the brines showed an 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^2- 4,and HCD^- 3. The type of brines was as follows: Na^+,-SO^2- 4,and-CL^-. By pondering about fairly neutral acidity and chemical investigation of the ingress waters, it was inferred that, the waters are of ca^2+ SO^2- 3, CL^- + SO^2- 4 HCO^- 3,HCO^- 3 ca^2+ + mg 2+. molar ratios, that follows the geochemical route П in the brines’ geochemical evolution diagram, which is similar to the brines present 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, while the least abundant minerals are Muscovite, Clinochlore, and Albite. Accordingly, source of the brines would be meteoric waters as well as neutral waters and brines with hydrothermal source.