Hydrogeochemical and Hydrogeological Investigation of the Can Geothermal Field

Abstract

The Can Geothermal Field is located on a central part of the Biga Peninsula in northwest Turkey. Volcanics are the dominant rock type in this region. Alteration zones and clay minerals are very common in these rocks. Sedimentary rocks, low-grade metamorphics and alluvium are other geological units observed around Can. These units include common fracture zones because of the tectonic activity in the region. Thermal waters have reached the surface via these fracture zones. Alluvium is the most productive aquifer in all geological units. Wells drilled in this unit yield between 5-30 L/s. The transmissibility and permeability coefficients of this unit are of 50-421 m(2)/day and of 1.01-16.8 m/day, respectively. In this aquifer, groundwater depth changes between 0.1 and 8.3m. According to the IAH (1979) water classification, these thermal waters are of the Na-Ca-SO4 type, the cold waters are of the Ca-Mg-HCO3 type and the snow samples are of a mixed water type. Geothermal waters have a meteoric origin. The mean temperature, electrical conductivity and pH of the thermal waters have values of 44.4 degrees C, 2941 mu S/cm and 6.9, respectively. Geothermometer equations were used for prediction of reservoir fluid temperatures of the geothermal system and temperature values were obtained between 46 and 203 degrees C. delta D, delta T and delta O-18 isotope analysis showes that thermal waters in the Can region have a meteoric origin and are a minimum of 45-50 years old.