| Title | Effects of major fault zones on geothermal reservoirs – a case study at Villarrica Volcano, southern Chile |
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| Authors | Held, S; Schill, E; Pavez, M; Diaz, D; Morata, D; Kohl, T |
| Year | 2016 |
| Conference | European Geothermal Congress |
| Keywords | Multidisciplinary exploration, magnetotellurics, chlorofluorocarbons, strontiumisotopy |
| Abstract | Near Villarrica volcano, located in southern Chile, a high number of thermal springs indicate moderate geothermal activity with reservoir temperatures between 80 and 140 °C. Although being one of the most active volcanoes in Chile, high temperature geothermal manifestations are not observed. Moreover, the area is characterized by a complex tectonic pattern of two major fault zones intersecting each other. Geochemical analysis disclose meteoric origin of the water with contributions >60 yrs and recent rain water. Local circulation patterns are characterised by low reservoir temperatures and low dilution along the LOFS and moderate reservoir temperatures and a higher amount of dilution away from the fault zones. A deep water component has not been detected. Strontium isotopy indicates equilibrium between thewater and surrounding rock. Geophysical data indicate mid- and upper crustal conductors that can be attributed to major fault zones. A connection between the structures in the different crustal levels cannot be excluded from geophysical measurements, but geochemical data point to a barrier between deep and meteoric fluids. We can conclude that the active faults govern the geothermal system by controlling the fluid movements in local small-scale circulation pattern. |