Topography growth drives stress rotations in the central Andes: Observations and models

Recent numerical models that couple global mantel circulation with lithosphere dynamics show that growth of the central Andes controls the 30% reduction of convergence velocity between the Nazca and South America plates observed over the past 10 Ma. The increase of gravitational potential energy due to topographic growth is also a major control on the stress pattern. Here we use numerical models which reproduce the Nazca/South America convergence history to predict the change of stress pattern in the central Andes for the past 10 Ma. Comparison of the modeled stress orientations at present-day with the observed ones results in +/- 23.9 degrees mean deviation. Based on this good agreement we attempt to predict paleostress orientations 10 Ma ago. Interestingly, the modeled stress orientations 3.2 Ma ago are very similar to the present-day orientations. From this result we infer that stress rotations occurred between 10 and 3.2 Ma ago, when topography was considerably lower.