Geochemical interpretation of thermal fluids from the Arbaer low-temperature field, S-Iceland

Abstract

Various physical and geological processes define the chemical properties of different geothermal fluids. Thermal waters ascending in geothermal systems may cool due to conduction of heat to the surrounding rocks; mixing with cooler water; boiling; or by more than one of these factors or a combination of them. In the same way, the origin of groundwater can make a difference to the final chemical composition. In this study, attempts are made to understand the different processes taking place in the Arbaer low-temperature geothermal field in the Southern Lowlands of Iceland, using all information available on the chemistry of the thermal fluids produced from the field. Applying different geothermometry and mixing models, it is estimated that the reservoir temperature may be as high as 170 C. The geothermal fluids are believed to originate partly from local heat-mining within the geothermal field and partly from sources far inland.