Estudio de tomografía de resistividad eléctrica en estructuras de los Andes Nordpatagónicos

BRAN, D. M.; LOZANO, J. G.; A.A. TASSONE; ALMARAZ, F,; VILLAROSA, G.; VILAS, J. F,

Tucuman

Congreso; XX Congreso Geológico Argentino-Tectónico de los Andes argentino-chilenos; 2017

Asociación Geológica Argentina

This work deals with the results of a Resistivity Tomography (ERT) survey, carried out in the northern sector of the North Patagonian Andes in order to investigate the subsurface continuity and geometric features of the Catedral and Pantanoso faults and some morphological lineaments. Resistivity profiles were measured using a 48 channel Syscal R1 switch. The equidistance between electrodes was 10 meters and the chosen array was the Wenner-Schlumberger, resulting in a penetration depth of around 70 meters. The inversion of resistivity data was achieved with the Res2D-Inv software of Geotomo Software Inc. The geophysical data was constrained with the analysis of outcrop measurements. The Catedral fault ERT showed a zone of low resistivity that correlates with an outcropping consolidated breccia, where several NW trending fault planes with inverse kynematics and medium to high inclinations were measured. Consequently, the Catedral fault could be characterized as a high angle fault zone of 100 meters width. The Pantanoso thrust ERT revealed a flexured low resistivity strip that was associated with an inverse structure, but in this case, with a gentle dip to the SW. The interpreted fault zone is truncated by a high resistivity wedge, attributed to the alluvial deposits that cover the surveyed area. On the other hand, the resistivity profiles accross the NE trending lineaments gave results that support their structural character, being controlled by the activity of faults with normal displacements. In addition, resistivity ranges were obtained for several lithological units of the area on the basis of outcrop correlation.