Architecture and kinematics of the Famatinian deformation in the Sierra Grande de San Luis: A record of a collisional history at 33° S latitude

Abstract

An improved understanding of the evolution of the Famatinian basement in the Sierra Grande de San Luis (SGSL) in Argentina is presented. Combining geological, geophysical and petrological data, a 3D inversion model for the basement rocks and their shear zones in the study area was constructed. The inversion model and the ground data show that the main deformation mechanism that affected the metamorphic complexes is related to a significant number of shear zones which delineate the architecture of the basement. Results suggest that the regional scale shear system (~40 km wide and ~120 km long) and the internal structural elements of the different tectonic domains are the product of an important crustal shortening. A contractional tectonic framework related to the indentation of the Cuyania/Precordillera microcontinent on the western Gondwana margin is proposed to be the cause of the tectonic mechanisms that led to a pop-up megastructure in the western sector of the SGSL and the closing of the Famatinian backarc.