Global scale models of the mantle flow field predicted by synthetic tomography models

Abstract

Using a multi-disciplinary technique incorporating the heterogeneous resolution of seismic tomography, geodynamical models of mantle convection, and relationships derived from mineral physics, we investigate the method of using seismic observations to derive global-scale 3D models of the mantle flow field. We investigate the influence that both the resolution of the seismic model and the relationship used to interpret wavespeed anomalies in terms of density perturbations have on the calculated flow field. We create a synthetic seismic tomography model from a 3D spherical whole mantle geodynamic convection model and compare present-day global mantle flow fields from the original convection model and from a geodynamical model which uses the buoyancy field of the synthetic tomography model as an initial condition. We find that, to first order, the global velocity field predicted by the synthetic seismic model correlates well with the flow field from the original convection model throughout most of the mantle. However, in regions where the resolving power of the seismic model is low, agreement between the models is reduced. We also note that the flow field from the synthetic seismic model is relatively independent of the density–velocity scaling ratio used.