Crustal anatomy and evolution of a subduction-related orogenic system: Insights from the Southern Central Andes (22-35°S)

As the archetype of mountain building in subduction zones, the Central Andes has constituted an excellent example for investigating mountain-building processes for decades, but the mechanism by which orogenic growth occurs remains debated. In this study we investigate the Southern Central Andes, between 22° and 35°S, by examining the along-strike variations in Cenozoic uplift history (<45 Ma) and the amount of tectonic shortening-thickening, allowing us to construct seven continental-scale cross-sections that are constrained by a new thermomechanical model. Our goal is to reconcile the kinematic model explaining crustal shortening-thickening and deformation with the geological constraints of this subduction-related orogen. To achieve this goal a representation of the thermomechanical structure of the orogen is constructed, and the results are applied to constrain the main decollement active for the last 15 Myr. Afterwards, the structural evolution of each transect is kinematically reconstructed through forward modeling, and the proposed deformation evolution is analyzed from a geodynamic perspective through the development of a numerical 2D geodynamic model of upper-plate lithospheric shortening.