CONICET | Buscador de Institutos y Recursos Humanos

The present work characterizes the deformation of the western margin of the Precordillera and its possible connection with major geological structures. In the western piedmont of the Sierra del Tigre (Western Precordillera of San juan), a series of minor fault scarps and folds of ~NNE-SSO trending strike is observed, which deforms the Pleistocene alluvial fans of the Sierra del Tigre. The present study investigates those fault scarps and folds, which are possibly linked to El Tigre fault to the west or to the backthrust with western vergence of the Sierra del Tigre. Three electrical resistive tomographies (north, central and south) were performed. Conductive features at high dip angle are observed and are interpreted as faults that generate different lateral configurations. The geological evidence and geophysical interpretations confirm the presence of neotectonic deformation in the western piedmont of the Sierra del Tigre, constituted by a main reverse fault with western vergence, an associated anticline and backthrusts with eastern vergence originated by tectonic adjustment. The deformation has greater magnitude to the north with Quaternary levels eroded in the anticlines, while to the south there are growing folds with Quaternary overlaps relations. The structural pattern allows us to conclude that the main fault would constitute a splay of the backthrust with western vergence of the Sierra del Tigre and confirms the propagation of a Pleistocene-Holocene deformation towards the west.