The source and heating mechanism for the Ahram, Mirahmad and Garu thermal springs, Zagros Mountains, Iran

The Ahram, Mirahmad and Garu low-temperature geothermal springs in the Zagros Mountains, Boshehr Province, Iran, emerge along the Ghatar-Kazeroon fault. The average temperature of the springs is about 40 °C and the waters have appreciable amounts of dissolved solids and hydrogen sulfide. Based on chemical analyses, including stable isotopes of the thermal waters and data interpretations, and on a comparison with fresh water springs and wells in the study area, we conclude that the hot waters are of meteoric origin. Because of the prevailing geothermal gradient, the waters are heated as they circulate deep in the system through joints, fractures and the Ghatar-Kazeroon fault. During their deep circulation, the waters come into contact with Hormoz Series evaporites and the oilfield brines, resulting in an increase in dissolved ion concentrations.