Three-dimensional geo-electrical structure in Juncalito geothermal prospect, northern Chile

Abstract

Magnetotelluric (MT) data were recorded to investigate a geothermal prospect in northern Chile. The exploration area is located in the Atacama region, at the southern edge of the Chilean Altiplano, at an altitude of ∼4100masl. This area belongs to the southern end of the Central Volcanic Zone (CVZ), a segment of the Andean Volcanic Belt associated with the oblique subduction of the Nazca plate beneath the South American plate. In the surveyed area of 19 MT sites, a two-dimensional geometry and an almost N-S geo-electric strike angle were obtained. A 3-D inversion was carried out and the obtained resistivity model shows a low resistivity layer (<10Ωm) thicker westward of the profile. This result agrees with the classic pattern of the geo-electric structure in a geothermal system with potential (Anderson et al., 2000; Spichak and Manzella, 2009). The results from these magnetotelluric measurements were compared with different geophysical and geological information gathered in this area, helping to understand the geo-electrical structure obtained by magnetotellurics and to characterize this geothermal prospect. Different possible scenarios, given the available data, are shown.