Investigation on Hydrothermally Altered Rocks in Salmās Geothermal Region, NW-Iran

摘要: Salmās region has 145 km2 area and is located in the Southeast of Salmās city in the Northwestern part of Iran. Based on the classification of Iran Techtono-sedimentary zones, this region is positioned in metamorphic-Ophiolithic belt of Sanandaj-Sirjan zone. Due to the presence of 8 warm springs (with temperature range from 27-40 C) in this region, it is believed that there is a geothermal reservoir in deeper part of it. Geologically, this region is composed of metamorphic rocks (with unknown age), Ruteh formation (dolomite), conglomerate, and ophiolitic complex and Qushchi granite. Zindasht (with nearly EW strike) and Tamarshurgol (with nearly NS strike) strike-slip faults are the most important faults of Salmās region. In order to study on geothermal potential of prospect region, its altered rocks were investigated. In this region by using ASTER satellite images, sampling of altered rocks and analyzing the samples with microscope and XRD method it is found that there are four types of hydrothermal alteration. They are including argillic, propylitic, silicic and Fe-oxide alterations. Using altered rocks (especially argillic ones) and other available data such as gravity survey results, travertine outcrops, warm spring location and faults map, it is revealed that an area between Kanisefid and Shurgol villages has a proper potential of geothermal energy in Salmās region. This area is located in the west side of central part of Salmās region. There is not any outcrop of young volcanic rocks in the study region so it is believed that Salmas geothermal region is a low–temperature geothermal resource.