Numerical modeling of stress and topography coupling during subduction: Inferences on global vs. regional observables interpretation

Abstract

The mechanical strength of the oceanic lithospheres exerts a fundamental control on the dynamics and tectonics of convergent margins. Here, we use numerical models of coupled subducting-upper plates and mantle to investigate the impact of the subducting lithosphere properties on the parameters commonly measured at subduction zones. The models predict a correlation among parameters such as subducting and convergence velocities, slab dip and curvature, and stress coupling with the upper plates, such signature emerges in a dynamic system through the slab buoyancy. Similar trends are found when assessing the impact of laboratory-constrained non-linear rheologies uncertainties on the mechanical strength and mantle flow, although some features are more affected. When the role of upper plate thickness is tested, we find a positive correlation of upper plate subsidence and fore-arc topography with the buoyancy of the down-going plate. However, plasticity in the crust limits the development of topography, becoming increasingly relevant with thinner upper plates, so that no correlation can be established. Similar control is found on the width of the long-wavelength dynamic subsidence, due to flexure, which increases non-linearly with the upper plate thickness. The models constrain relations among parameters within the dynamic system driven that allow inferences on the observable parameters. The comparisons supports the idea that the subduction dynamics emerges as a global phenomenon in plate motions, bending and dynamic subsidence, yet Andean-type margin tectonics is best addressed in a regional context.