Predrilling Geothermal Studies at Mount Sabalan, NW Iran

Abstract

A detailed surface exploration survey at Mt. Sabalan conducted in 1998 has provided sufficiently good indications of geothermal resource potential to justify deep exploration drilling, the first to be undertaken in Iran. An integrated DC/ TEM/ MT geophysical survey has identified five low-resistivity anomalies to approximately 2000 m depth. Four of these are associated with areas of surface thermal springs. An exploration model is proposed which describes the key features of the Sabalan geothermal prospect. The primary heat source is an intrusive associated with resurgent caldera magmatism. The intrusive is locally exsolving magmatic volatiles at temperatures in excess of 300oC. These volatiles condense into an extensive carapace of shallow ground water and partially re-equilibrate at about 120?C. Peripheral to the magmatic system, and below the thermalized ground water system, there is a convective meteoric water system which receives heat and mass from the magmatic system. This is the main target for exploration drilling with the objective of developing a 100-MWe pilot power plant.