Geochemical characterization of thermal waters in the Borateras Geothermal Zone, Peru

Abstract

The Borateras Geothermal Zone (BGZ) is located in the Western Cordillera of the Andes in southern Peru. In Borateras volcanic chains which are NW-SE aligned, volcanic rocks have been deposited over sedimentary Cretaceous basement. The geochemical interpretation of the results using Langelier and Pipper diagrams show us that thermal waters are alkaline-chloride water type. The triangular diagram shows that most of geothermal waters plot close to the chloride corner which is typical of mature geothermal deep fluids. High B concentrations lead to a relatively high B/Cl ratio as shown on a B-Cl binary diagram. This can be used to elucidate the reactions of waters with sedimentary marine rocks at deep levels. The G18O vs GD diagram shows a relatively high temperature or poor permeability. The results for chemical geothermometry allowed us to estimate the temperature at the depth of the geothermal resources to be as high as 200°C.