The influence of variations in crustal composition and lithospheric strength on the evolution of deformation processes in the southern Central Andes: insights from geodynamic models

Deformation in the orogen-foreland system of southern Central Andes between 33° and 36° S varies style, locus, amount shortening. The controls that determine these spatially variable characteristics have largely remained unknown, yet both subduction oceanic Nazca plate strength South American been invoked to play a major role. While parameters governing processes are similar S, lithospheric upper is due structures inherited from past geodynamic regimes associated compositional differences plate. Regional Mesozoic crustal horizontal extension generated < 40-km-thick crust with more mafic composition lower south 35°S; north this latitude, however, felsic inferred geophysical data. To assess influence different structural heterogeneities on style deformation Andes, we developed suite models intraplate shortening for two E–W transects (33° 40? S) across Andes. constrained by local geological information. Our results demonstrate decoupled mode brittle ductile those areas characterized (36° transect). In contrast, crust, such as transect, coupled mode. Furthermore, find thickness asymmetry lithosphere–asthenosphere boundary may promote formation crustal-scale, west-dipping detachment zone drives overall lateral expansion orogen. study represents first modeling effort aimed at understanding roles (crustal thickness) scale entire lithosphere well geometry respect mountain building.