A lithosphere-dynamics constraint on mantle flow: Analysis of the Eurasian plate

Abstract

We present a method to estimate the poorly understood mechanical coupling between lithosphere and underlying mantle, and apply it to the Eurasian plate. Mechanical equilibrium of tectonic plates requires the torque from mantle tractions (T M) to be balanced by the torques from edge forces (T E) and lithospheric body forces (T B). The direction of T E proves tightly constrained by plate boundary nature but T B is affected uncertainties in the density structure of continents. We consistently find that the non-zero torque required from mantle tractions does not agree with the orientation of any published absolute motion model. We conclude that mechanical balance of the Eurasian plate requires an actively convecting mantle, which should result in a torque on the Eurasian plate located in the southwest Pacific. © 2010 by the American Geophysical Union.