3-D modeling of magnetotelluric data in the San Pedro-Linzor volcanic chain, Central Andes, northern Chile.

Abstract:

The research is located in the San Pedro-Linzor volcanic chain, in the central volcanic zone of the Andes, northern Chile. This area is interesting because of its proximity to several active volcanic centers, the geysers field of El Tatio and the recently opened geothermal plant Cerro Pabellon.

Thermobarometry studies made in the area point to magma accumulated at 8 km below Chao Dacite, and depths greater than 16 km below Toconce, Cerro de Leon and Linzor volcanoes. Regional geophysical studies show a distribution of conductive bodies around the complex, but the resolution of these studies at shallow depths are not conclusive. Data from wells show the possible presence of a large geothermal system in the southwestern part of the complex, with depths of ~2 km.

Twenty broadband magnetotelluric (MT) stations were measured in the vicinity of the complex and combined with 15 long period MT stations measured in the 1990s, aiming at characterizing the deep conductive structures previously observed in the area, with magmatic bodies associated with the adjacent volcanic system.

The results of a 3-D inversion show several conductive anomalies around the complex. Analyses of conductivity together with the 3-D models obtained indicate the presence of a geothermal system to the southwest of the complex with maximum depths of about 5 km, and two possible magmatic chambers below Paniri volcano and between Paniri and San Pedro volcanoes. In addition, the presence of a highly conductive structure to the east is obtained, associated with the Altiplano-Puna magma body (APMB).