Hydrogeochemistry and Isotopic Investigation of Barudab and Malusan springs of Nahavand area output from Carboniferous-Permian limestones (Introduce ancients’ host rocks in Sanandaj-Sirjan zone in Iran)

Sanandaj-Sirjan zone is the most dynamic tectonic zone in Iran. The research method of the present study was survey-laboratory. The hydrogeochemical and isotopic properties of Malusan and Barudab springs (Nahavand) and their closest schist springs (Abolfazl and Siadreh) are investigated. To evaluate the water quality of springs, physical properties (electrical conductivity, temperature, TDS, and pH), turbidity, anion concentrations (Nitrate, nitrite, chloride, fluoride, and sulfate), carbonate and bicarbonate, main cations (sodium, potassium, calcium, and manganese), total concentration of 11 poisonous/heavy elements (ferric, arsenic, cadmium, cobalt, copper, zinc, lead, nickel, manganese, mercury and barium) and finally the stable isotopes δ18O and δ2H were analyzed. Discharge was measured with a volumetric and flowmetric method at the site. Based on alpha coefficient and field observations the karst of Barudab region is moderate karst and the karst of Melusan region is located between moderate karst and incomplete karst (Merv karst). Also, karst reservoir of Malusan has trinary porosity system due to the existence of cavity porosity and fractures along with primary porosity in synchronic, but karst reservoir of Barudab spring has only primary porosity. Stable oxygen isotopes 18 and deuterium of Baroudab spring have concentrations higher than Melousan spring due to high feeding height. Catchment area of ​​the springs is not the same as the surface boundary due to different slopes and drainage is done by stratifications and faults. so origin of karst springs is to some extent influenced by secondary and inter-structural processes, with autogenic recharge. Based on the findings, Malusan and Barudab springs are representatives of the oldest karst reservoirs in Sanandaj-Sirjan zone in Iran.