INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
Pre-Andean deformation of the southern sector of the Precordillera, Southern Central Andes
GIAMBIAGI, L. B.; MESCUA, J. F.; BECHIS, F.; MARTÍNEZ, A.; FOLGUERA, A.
GEOLOGICAL SOC AMER, INC
Año: 2011 vol. 7 p. 219 - 239
This paper presents a detailed investigation of the structure and evolution of the southern sector of the Precordillera. We document the development and successive reactivation of regional and discrete structural grain through time and discuss the existence of a large-scale mechanical anisotropy present in the lithosphere. Our kinematic studies indicate that the Permian orogeny generated a double-vergent fold and thrust belt of transpressive deformation, where strain was partitioned into two different types of deformation domain. The west-vergent western domain was characterised by partitioned transpression with shortening dominated and a strike-slip dominated subdomains. The east-vergent eastern domain was characterised by pure contractional deformation. Our model for the Late Permian to Early Triassic evolution of the Precordillera, NNE-directed extension affected a NNW-trending weakness zone, generating an area with transtensional deformation during the Choiyoi volcanism development. Afterward, during the Triassic generation of the Cuyana rift basin, the NE stretching direction was orthogonal to the rift trend, indicating a pure extensional deformation. We propose a model where the clear parallelism between the distributions of an inferred Eopaleozoic suture zone, a NNW-trending Late Paleozoic belt, and Permo-Triassic rift-related magmatism, indicates the reactivation of a NNW-trending long-live lithospheric weakness zone.