Computer models of mantle convection constrained by the history of Cenozoic and Mesozoic plate motions explain some deep-mantle structural heterogeneity imaged by seismic tomography, especially those related to subduction. They also reveal a 150-million-year time scale for generating thermal heterogeneity in the mantle, comparable to the record of plate motion reconstructions, so that the probl...

Bends in volcanic hotspot lineaments, best represented by the large elbow in the Hawaiian-Emperor chain, were thought to directly record changes in plate motion. Several lines of geophysical inquiry now suggest that a change in the locus of upwelling in the mantle induced by mantle dynamics causes bends in hotspot tracks. Inverse modeling suggests that although deep flow near the core-mantle bo...

[1] The thermal boundary layer beneath continental cratons extends into the Earth’s mantle to depths of at least 200 km. It has been proposed that chemical depletion of the lithospheric mantle during partial melting offsets the effect of increased density from conductive cooling, resulting in neutral buoyancy with respect to the underlying asthenosphere. Mineral compositions of garnet peridotit...

MD simulations with pairwise potential on MgO and MgSiO3 vacancies pair were conducted to obtain the Newtonian viscosity of lower mantle. The results of MgO are such that the viscosity of the upper half portion in the lower mantle shows uniform structure but in the lower half it rapidly decreases to the core mantle boundary by two order of magnitude. On the other hand, the viscosity of MgSiO3 p...

W e consider a series of simple calculations with a step-function change in thickness of the lithosphere and imposed, far-field boundary conditions to illustrate the influence of the lithosphere on mantle flow. We consider the effect of aspect ratio and far-field boundary conditions on the small-scale flow driven by a discontinuity in the thickness of the lithosphere. In an isothermal mantle, w...

"Lithosphere" is a mechanical concept implying strength and relative permanence. Unfortunately, the term has also been applied to the surface thermal boundary layer (TBL) and a shallow enriched geochemical reservoir, features having nothing to do with strength. The "strong" lithosphere is about one half the thickness of the TBL. The bottom of the elastic plate, the maximum depths of midplate an...

It has been claimed that focused hot cylindrical upwelling plumes cause many of the surface volcanic hotspots on Earth. It has also been argued that they must originate from thermal boundary layers. In this paper, we present spherical simulations of mantle circulation at close to Earth-like vigor with significant internal heating. These show, in addition to thermal boundary layer plumes, a new ...

The core mantle boundary (CMB) separates Earth's liquid iron outer core from the solid but slowly convecting mantle. The detailed structure and dynamics of the mantle within ~300 km of this interface remain enigmatic: it is a complex region, which exhibits thermal, compositional and phase-related heterogeneity, isolated pockets of partial melt and strong variations in seismic velocity and aniso...