| Abstract |
The Paucarani geothermal zone is located in the Western Cordillera of the Andes of southern Peru, is characterized by the presence of fumarolic vapor (solfataras) and thermal spring discharge, associated to volcanic rocks (less 3 Ma), that overlie Mesozoic sedimentary rocks and Paleogene-Neogene volcanism controlled by the Incapuquio regional fault system and dextral Paucarani fault that exerts the structural control of the volcanic rocks. The NW-SE lineaments established the boundary between the pyroclastic and epiclastic sequences, with the andesite-dacitic Barroso Group lavas, the last event correspond Paucarani volcano lavas (less1 Ma). The hot-springs chemical composition with surface temperature between 17.2°C – 81°C, are classifying in following waters types Na-Cl, Ca.Mg-SO4.Cl and Ca.Mg-HCO3, and the geothermometers estimated the reservoir temperatures from 221°C (SiO2), 120°C (K / Mg) and less 260°C (Na-K-Ca), the fluid-rock interactions have been not reached to full equilibrium; probably related to an active magmatic system manifested by the presence of highly acidic fluids (strong smell sulfurs). The pH of hot-springs fluids shows variation from 1.5 to 8.7. The values of δ2H and δ18O indicate that the fluids originate from a mixture of magmatic fluid and meteoric water that infiltrate at a deep level by fault systems of NW-SE and ENE-WSW direction. The geophysical magnetotelluric method identified a conductive anomaly (less10 Ohm * m) from the surface to 2000 meters deep, associated with the clay cap, with a thickness of 1200m and a resistive anomaly (8 -70 Ohm * m) with an average thickness of 1500 meters linked to the reservoir. In addition of this detected a conductive anomaly from 7000 meters, related to geothermal fluid ascent. Also, was identified the presence of negative anomalies to SW and SE of the study area related to the geothermal flow associated with the fault system and fractures of NW-SW, EW and NE-SW direction. The Geological, geochemical and geophysical results was integrated for to elaborate conceptual model for the Paucarani geothermal system, that indicate the geothermal fluids are associated with magmatic sources. In addition was determined the geothermal potential of 72 MWe at a 62% probability for a minimum area of 10 km2. |