Abstract

CASA, Analía L. et al. Quaternary deformation associated with the eastern uplift front of  the Sierras de Velasco and Ambato, western Sierras Pampeanas. Rev. Asoc. Geol. Argent. [online]. 2010, vol.67, n.4, pp.425-438. ISSN 0004-4822.

Along the eastern front of  the Sierra de Velasco and at the southern end of  the Sierra de Ambato, western Sierras Pampeanas, have been found new evidences of  Quaternary tectonic activity near La Rioja city. Observed evidences correspond to different reactivated sections of  the faults that bound the mountain fronts, as well as to structures affecting the Quaternary deposits on the piedmont. The bounding faults of  the Sierra de Velasco Oriental-front exhibit a NNE trend and WNW dip, while structures at the southernmost Ambato range are characterized by NE trend and NW dip. The neotectonic faults of  the El Carrizal block are the result of  the interference of  both structural trends, resulting in a sector with higher structural complexity. The here described deformation show the persistence of  a compressive regime during the Quaternary, with eastern to southeastern verging reverse faults. It is considering that these faults are driving the current uplift of  the mountain ranges and constitute potential earthquake sources.

Keywords : Neotectonics; Quaternary; Sierras Pampeanas; Velasco range; Ambato range.

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