Distribution, timing, and causes of Andean deformation across South America

COBBOLD, P.R., E.A. ROSSELLO, P. ROPERCH, C. ARRIAGADA, L.A. GÓMEZ Y C. LIMA

Deformation of the continental crust: The legacy of Mike Coward

Geological Society of London Special Publications

Lugar: Londres, Reino Unido; Año: 2007; p. 321 - 343

Abstract: The Andean Orogeny in South America has lasted over 100 Ma. It comprises thePeruvian, Incaic and Quechuan phases. The Nazca and South American plates have beenconverging at varying rates since the Palaeocene. The active tectonics of South America arerelatively clear, from seismological and Global Positioning System (GPS) data. Horizontalshortening is responsible for a thick crust and high topography in the Andes, as well as in SEBrazil and Patagonia. We have integrated available data and have compiled four fault maps atthe scale of South America, for the mid-Cretaceous, Late Cretaceous, Palaeogene and Neogeneperiods. Andean compression has been widespread since the Aptian. The continentalmargins have registered more deformation than the interior. For the Peruvian phase, notenough information is available to establish a tectonic context. During the Incaic phase,strike-slip faulting was common. During the Quechuan phase, crustal thickening has beenthe dominant mode of deformation. To investigate the mechanics of deformation, we havecarried out 10 properly scaled experiments on physical models of the lithosphere, containingvarious plates. The dominant response to plate motion was subduction of oceanic lithospherebeneath continental South America. However, the model continent also deformed internally,especially at the margins and initial weaknesses.