Abstract

ANALIA LAURA, Casa; CORTES, José María  and  BORGNIA, María Marcela. Pleistocene evidences of deformation in the La Carrera fault system (32º40'-33º15'LS), Cordillera Frontal of Mendoza. Rev. Asoc. Geol. Argent. [online]. 2010, vol.67, n.1, pp.91-104. ISSN 0004-4822.

Between 32º25' and 33º15' LS, Cenozoic uplifting front of the Cordillera Frontal, shows evidence of Pleistocene reactivations and is represented by the La Carrera fault system. In the eastern margin of the Del Plata range, the distribution of Quaternary deformation is not homogeneous. At the latitude of the El Salto village, such evidence is concentrated in a stretch between the 32º55' and 33º05' LS, both in mountain front and in the adjacent piedmont. In the mountain, neotectonic activity is associated with the Río Blanco fault, which delimits the front. In the piedmont a splay of this fault affected a rock pediment and its alluvial Pleistocene coverage, while a second Quaternary fault (the El Salto fault) uplift three levels of Quaternary pediments. Piedmont fault scarps are also presented in the alluvium. In this mountainous stretch drainage basins are poorly developed, there are calculated low values of mountain front sinuosity index (Smf) and valley-floor width to valley height ratio (Vf), and high values of stream-gradient index (SL). This set of evidence suggests a persistent Quaternary tectonic activity along the structural segment of the mountain front of the Del Plata range and the piedmont area associated. The evidence identified in latitude of the El Salto, seem to be the northern continuation of the La Aguadita fault and expand the scope of Quaternary deformation within the La Carrera fault system.

Keywords : Neotectonics; Quaternary; Morphometric indexes; Cordillera Frontal.

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