3D litho-constrained inversion model of southern Sierra Grande de San Luis: New insights into the Famatinian tectonic setting

Unravelling the orogenic structure of the Sierra Grande de San Luis (Argentina) is essential to understand the geological evolution of the Famatinian orogen and the western margin of Gondwana. However, its structural organization is still poorly known and widely debated. In this contribution, a new interpretation of the complex geological structures in the southern sector of the Sierra Grande de San Luis is presented. This work is based on a litho-constrained joint inversion of gravity and magnetic datasets combining lithological, structural and rock properties information. Results are consistent with a large-scale doubly-vergent structure caused by a compressional tectonic setting as a consequence of the collision between an allochthonous terrane (Cuyania/Precordillera) and the proto margin of Western Gondwana. A convex morphology of the indenter is proposed to be responsible for producing a significant clockwise rotation of the horizontal deviatoric stresses. This stress field caused a small sinistral component of movement and gave rise to the doubly-vergent transpressive mega-structure. Fil: Christiansen, Rodolfo Omar. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina Fil: Morosini, Augusto Francisco. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; Argentina