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

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Abstract

[1] 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° 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.

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