Thermochemical structure and dynamics of the African superplume

We present a new three‐dimensional (3‐D) model of the thermochemical structure of the African superplume region obtained from simultaneous inversion of global seismic and convection‐related data. Convection‐related observations include the global free‐air gravity field, tectonic plate motions, dynamic surface topography and the excess ellipticity of the core‐mantle boundary. A 3‐D image of the chemically‐induced density perturbations provides direct evidence that intrinsically‐dense material is entrained within the superplume and concentrated into a rounded structure ∼1000 km above the core‐mantle boundary. The thermally‐induced density perturbations are greater in magnitude than the chemically‐induced implying overall positive buoyancy throughout the superplume. The observed morphology and density signatures are consistent with a thermochemical plume that has risen from a compositionally‐distinct ‘pile’ at the base of the mantle and may be currently deforming under the influence of its intrinsic negative chemical buoyancy.