Evidences of active transpression in the northern area of the Western Precordillera (Provinces of San Juan and La Rioja, Argentina

PERUCCA, L. Y BASTIAS, H.

Cenozoic Geology of the Central Andes of Argentina

SCS PUBLISHER

Lugar: SALTA; Año: 2011; p. 329 - 336

We present in this paper some geomorphic, stratigraphic, and structural data indicating neotectonic deformation in the northern Western Precordillera region of San Juan and La Rioja provinces (Argentine Central Andes) which includes a significant contractional component associated with a translational strain. Neotectonic deformation in the area is dominated by strike-slip faults with NS-trending and right-lateral displacements. Most of the contractional features appear to be related to some combination of transpressive strains along the La Bolsa, Las Majaditas and Punilla faults. It is possible to consider tentatively sierra de La Punilla structure as a positive flower structure, with a central right-lateral strike-slip fault and reverse or strike-slip faults in the flanks, with associated folding. Existence of a recurrent zone of weakness through time in coincidence with the present occidental border of Precordillera is indicated too by the magmatic events recognized in the area in the Ordovician, Late Paleozoic-Early Mesozoic, and Middle to Late Tertiary.