| Title | Calabozos Hydrothermal System: An Approach from Petrology and Geochemistry of Hydrothermal Alteration. |
|---|---|
| Authors | Villarroel M, Morata D, Maza S, Ruprecht P |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | The Chilean Andes are characterized by extensive volcanic activity and contain some of the world’s most promising, yet underutilized, geothermal resources. The Calabozos Caldera Complex (CCC) is one such area with high geothermal potential due to its magmatic history, structural complexity, and outstanding hydrothermal activity. However, despite its potential, the CCC remains largely unexplored and there is no comprehensive geothermal model that integrates surface and subsurface data. The Calabozos Caldera Complex (35° 30' S, 70° 37' W), defined by Hildreth et al. (1984), is located in the Maule Region, 25 km northeast of the Descabezado Grande-Quizapu-Cerro Azul volcanic complex, at an elevation of 2,600 meters. Hildreth et al. (1984) mapped the caldera and determined its diameter to be 26 x 14 km, dating from the late Pleistocene. A notable feature of the CCC is the presence of thermal manifestations, with surface temperatures reaching up to 94°C (Benavente et al., 2016), which suggests the presence of a geothermal reservoir at depth. In 2009, Empresa Nacional de Geotermia S.A. (ENG) drilled the Llolli-1 well, reaching a depth of 901 meters, with a recorded temperature profile of 182°C at 889 meters. Preliminary analyses suggest that the CCC hosts a unique geothermal system that has developed within an alternating sequence of Mesozoic andesites and sedimentary (carbonates and evaporites) units. Based on alteration mineralogy studies (XRD and SEM) along the Llolli-1 drill core coupled with remote sensing analyses, we propose to develop a conceptual model of this caldera-related geothermal system. |