In the southern Central Andes (~32°S), subduction of the Nazca oceanic plate beneath the South American continental plate becomes horizontal. The growth of the Altiplano-Puna Plateau is covalently related to the southward migration of the flat subduction, but the role of subduction geometry and the plate strength on current and long-term deformation of the Andes remains poorly explored. This study takes a data-driven approach of integrating the previous structural and thermal model of the lithosphere of the southern central Andes into a 3D geodynamic model to explore the different parameters contributing to the localization of deformation. We simulate visco-plastic deformation using the geodynamic code ASPECT. The repository includes parameter files and input files for the reference model (S1) and the following alternative simulations: a series of models with variation in friction at the subduction interface (S2a-d), a series of models with variation in sedimentary strength (S3a-d), a series that studies the effect of topography (S4), and a series that studies the effect of plate velocities. In addition, a readme file gives all the instructions to run them.
The southern Andes are regarded as a typical subduction orogen formed by oblique plate convergence. Despite decades of studies, there is considerable uncertainty as to how deformation is kinematically partitioned in the upper plate. Using scaled analogue experiments modelling, we test the concept of dextral transpression for this orogen. We advocate that the GPS velocity field portrays interseismic deformation related to deformation of strong crust north, and weak crust south, of 37°S. Contrary to the popular hypotheses that the Liquiñe-Ofqui Fault Zone, a prominent intra-arc deformation zone, takes up most of the plate boundary-parallel dextral strike-slip, we find that dextral transpression affects the entire model orogen through tectonic segmentation of crust.
Moreover, prominent, regularly spaced sinistral oblique-slip thrust faults, interpreted as antithetic Riedel shears, developed spontaneously in all of our experiments and call into question the general believe that their NW-striking natural equivalents formed from pre-Andean discontinuities. Our experiments prompt us to reconsider the apparently well-established geodynamic concept that strain and margin-parallel displacement is localized on a few margin-parallel faults in the southern Andes.