| Abstract |
Chile has a huge potential for the utilization of geothermal energy that is associated with active volcanism. This resource has remained largely untapped so far but efforts on geothermal exploration have been increased recently and are also part of this study. The study area is located in the vicinity of the mt. Villarica in southern chile, which is one of the most active volcanoes of chile (Ortiz 2003). Numerous hot springs can be found in the surrounding area that indicate a large geothermal system (Fig. 1). As part of the south volcanic zone mt. Villarica belongs to a nw‐se striking chain of three major stratovolcanoes (Villarrica‐quetrupillan‐lanín). This chain and a related parallel fault zone crosscut and offset the major n‐s striking liquIñe‐ofquI fault zone (Lofz) (Cembrano et al. 1996) By a few kilometers at the surface (Rosenau et al. 2006). In the villarica area, a large number of natural hot springs distributes over an area of 2000 km2. Temperatures of thermal waters at the outlets do not exceed 80 °c and reservoir temperatures determined using δ18o isotopes of so4 and h2o to be about 130‐140°c (Held et al. 2015). The tectonic situation, including the over >1000 km n‐s extending lofz, may be responsible for the presence of a high number of geothermal springs. Furthermore a change in basement geology is observed. South of the volcanic chain granitoid basement rocks are present, including the tonalite used in this study (Part of the north patagonian batholite). North of the volcanic chain those granitoid basement rocks are continuously replaced by a volcano‐sedimentary unit called cura‐mallín formation that contains the porphyric andesite used. The purpose of the ongoing kit‐cega collaborative research project multigeoex is to establish diverse geochemical (Source‐rock deduction, geothermometry) And geophysical exploration methods (E.G. Magnetotellurics) To assess the impact of the volcano and cross‐cutting major fault zones on subsurface fluid migration. Within a broader context of geothermal exploration the aim of this work is to study the geochemical characteristics of natural fluids, which have been in contact to reservoir rocks, in order to derive information about the subsurface conditions (Temperature, fluid migration paths, mineralogy of the reservoir). Because it is expected that the natural geothermal fluids carry distinct chemical signatures, fluid‐rock‐experiments have been performed in the laboratory. The results can assist to better understand the reactivity of these rocks and enable to test the application of geochemical tools, such as source‐rock deduction and geothermometry. Preliminary results from the experimental campaign are presented and tested in this particular geological setting. |