Relationship between slab dip and topography segmentation in an oblique subduction zone: Insights from numerical modeling

Abstract

Slab dip controls the state of stress in an overriding plate and affects mountain building. Analog and numerical models have shown variations in tectonic regime induced by slab folding over the 660 km depth discontinuity zone in orthogonal convergence. Here using a three-dimensional model of oblique subduction (30°) and accounting for free top surfaces, we show how slab folding generates an along-strike slab dip segmentation, inducing variations in topography of the overriding plate. When the subducting plate begins to curve forward, the elevation height rises inland and varies along the trench from 5 km to 2 km. The Andes are a suitable natural zone to compare our results with because of its linear margin and well-constrained plates kinematics. Thus, we provide a new explanation to the general decrease in elevation from the central to southern Andes, which still remains to be combined with other 3-D mechanisms to explain the actual Andean topography.