Geological and Tectonic Settings Preventing High-Temperature Geothermal Reservoir Development at Mt. Villarrica (Southern Volcanic Zone): Clay Mineralogy and Sulfate-Isotope Geothermometry

Abstract

In the vicinity of the volcano Villarrica (South-Central Chile), geothermal manifestations at the surface are evident revealing low-enthalpy geothermal processes in the subsurface. The structural geology of the area, postulated by (Sanchez et al., 2013), set up a first draft of a structural model but also naming the complexity of the structural geology in the area generated by the interaction of two major fault systems and a change in the basement geology. In the first phase of the actual research project, geochemical methods are used to characterize the geothermal system. Besides standard geochemical techniques, clay mineralogy and δ18O[SO4]/δ18O[H2O] isotopes are used to determine the characteristics of the geothermal reservoir. The results of these techniques, pointing at a low-enthalpy reservoir in the vicinity of the active Villarrica volcano, are discussed in context of the special tectonic characteristics in the investigation area.