Shallow anatomy of hydrothermal systems controlled by the Liquiñe-Ofqui Fault System and the Andean Transverse Faults: Geophysical imaging of fluid pathways and practical implications for geothermal exploration

Abstract

We combined geoelectric and seismic ambient noise methods to image the shallow depth (<30 m) distribution of thermal waters in two fault-controlled hydrothermal systems located in southern Chile. The bedrock depth was constrained with seismics, while hotsprings and mapped faults were imaged by low-electrical-resistivity domains (<160 ?m) de?ned with electrical resistivity tomographies (ERT). The distribution and shape of low-resistivity- domains suggest that thermal ?uids follow complex pathways, including deep vertical conduits hosted in frac-tured rock and shallow horizontal bodies hosted in sediments. These results indicate that the studied hydro-thermal systems are at least twice longer within the sediments than the super?cial area covered by hotsprings.