Structural evolution of the Quebrada del Toro Basin: Influence of pre-cretaceous structures on the Andean fold-and-thrust belt in the Argentinian Eastern Cordillera

Abstract

The superimposition of the tectonic events recorded in the Argentinian Eastern Cordillera conditioned the current structural style. In the Quebrada del Toro Basin (Salta province), coinciding with the central section of the Calama-Olacapato-Toro lineament (COT), pre-cretaceous structures are recognized that would have favored the development of inverse structures during Andean tectonics. We present new structural, stratigraphic and sedimentological data which allowed an integral analysis through the generation of balanced geological sections, deformation restorations and 2D forward modeling. At least two deformation events were identified: the first, during the upper Tremadocian, corresponds to the Tumbaya extensional phase expressed through two NNW-SSE striking and ENE dipping normal synsedimentary faults (de la Cruz and Pascha). The second deformation event, of compressive nature, would have begun during the middle Eocene, with the generation of large-scale folds related to relatively shallow Gólgota thrust and their subsequent transport by two high angle reverse faults (Gólgota and Lampazar) with deeper detachment. In this sense, Paleozoic structures controlled the location and western vergence of the Gólgota thrust in the study area, a caracteristic that reinforces the hypothesis about the preponderant influence of Ordovician normal faults on western vergence thrusts.