Evaluating the Influence of Plate Boundary Friction and Mantle Viscosity on Plate Velocities

Abstract

AbstractLithospheric plates move over the low‐viscosity asthenosphere balancing several forces, which generate plate motions. We use a global 3‐D lithosphere‐asthenosphere model (SLIM3D) with visco‐elasto‐plastic rheology coupled to a spectral model of mantle flow at 300 km depth to quantify the influence of intra‐plate friction and asthenospheric viscosity on plate velocities. We account for the brittle‐ductile deformation at plate boundaries (yield stress) using a plate boundary friction coefficient to predict the present‐day plate motion and net rotation of the lithospheric plates. Previous modeling studies have suggested that small friction coefficients ( , yield stress MPa) can lead to plate tectonics in models of mantle convection. Here we show that in order to match the observed present‐day plate motion and net rotation, the frictional parameter must be less than 0.05. We obtain a good fit with the magnitude and orientation of the observed plate velocities (NUVEL‐1A) in a no‐net‐rotation (NNR) reference frame with and a minimum asthenosphere viscosity of Pas to 1020 Pas. Our estimates of net rotation (NR) of the lithosphere suggest that amplitudes ( /Ma), similar to most observation‐based estimates, can be obtained with asthenosphere viscosity cutoff values of Pas to Pas and friction coefficients .