Geochemical interpretation of the Masaya-Granada-Nandaime chemical data Nicaragua

Abstract

The available chemical data for the Masaya-Granada-Nandaime area have been evaluated applying HCO3-Cl-SO4 and Na-K-Mg ternary diagrams, geothermometry (silica and cation), isotopes, mixing models and speciation using the WATCH program. According to the HCO3-Cl-SO4 ternary diagram, only the water samples from Apoyo Lagoon and Granada City region show potential for a geothermal system, and also a possible region with high permeability. According to the Na-K-Mg ternary diagram, the water samples are possibly composed of a mixture of geothermal water and surface waters or plain surface waters. The temperatures predicted using silica and cation geothermometers are not in a good agreement, with the predicted silica temperatures always lower than the predicted cation temperatures. The results suggest the existence of a geothermal system with the Apoyo Lagoon region at its centre.