CO2-rich thermomineral groundwater in the Betic Cordilleras, southeastern Spain: Genesis and tectonic implications

The CO2-rich thermal groundwater in the Betic Cordilleras in Spain has been studied with regard to the geological and hydrogeological setting, physical and chemical characteristics, and 13C-isotope content. The study area is about 60 km northeast of Almería city, in southeastern Spain. The thermomineral waters are plentiful and are related to regional geothermal anomalies. Temperatures of 20-41°C, high bicarbonate concentrations (183-1824 mg/L), and high amounts of PCO2 (<1.1 bar) characterize the groundwater. CO2 spatial variations are related to proximity to the Carboneras, Palomares, and Guadalentín fault systems, which may be the surface representation of the zone of crustal thinning and magmatism. δ13C values probably indicate a deep source for the CO2, either the mantle or perhaps carbonate rocks in the metamorphic substratum. The high amount of CO2 in the groundwater causes problems in wells and severely restricts water usage. The hydrothermal features of this area are probably related to neotectonic activity.