Permo-Triassic oblique extension along an ancient lithospheric anisotropy

L. GIAMBIAGI Y A. MARTINEZ

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

Pergamon

Año: 2008 vol. 26 p. 252 - 260

0895-9811

The Permo-Triassic evolution of southwestern South America was characterized by the development of a great amount of volcanism under extensional conditions. Structural analyses of faults developed coetaneously with this volcanism in the key area of Potrerillos-Uspallata, suggest the existence of an oblique-extensional setting primary controlled by the presence of a pre-existing lithospheric anisotropy. A clear parallelism between the trace of an inferred Devonian suture zone, the Late Paleozoic San Rafael orogenic belt, and the Permo-Triassic rifting, suggests that Early and Late Paleozoic tectonic inheritance permitted the reactivation of a NNW-trending long-live lithospheric weakness zone. The reactivation of this pre-existing weakness zone during Late Permian to Early Triassic time has resulted in the generation of a new complex fault system, which concentrated the oblique-slip normal displacement related to a NNE-SSW stretching (N23ºE).