Geochemical Interpretation of Bicarbonate Thermal Springs for the Comprehension of a Geothermal System: A Case Study at Cerro Machin Volcano, Colombia
Esteban GÓMEZ DIAZ
[EMR, RWTH Aachen University, Germany]
Cerro Machin volcano is an active volcano located on the eastern flank of the Cordillera Central of Colombia with thermal springs dominated by two types of bicarbonate waters; Na-HCO3 and Ca-HCO3 waters. The chemical components and δ18O and δ2H isotopes analyses were used to characterize the waters and their relationship with the geothermal system. Na-HCO3 springs are less affected by the dilutions/mixing processes and they were suitable for some geothermometers, whereas the Ca-HCO3 springs are more strongly affected by this subsurface process, and not suitable for geothermometry. The equilibration temperatures determined by geothermometry is between 158°C to 246°C. Application of the chloride enthalpy model suggests a hot parent water of about 282°C. The stable isotope compositions of the geothermal waters indicate a meteoric origin, and the waters became enriched in CO2 by steam-heating and gas adsorption. The geothermal system is a convection-dominated geothermal play associated to recent volcanism and, with an intermediate reservoir temperature around 200 - 230°C and, a possible deep high enthalpy reservoir around 280°C.
|        Topic: Geochemistry||Paper Number: 14023|