The proposed research is to study flow and chemical transport in the mantle resulting from convection and plate tectonics. It is motivated by the discordant inferences about mantle structure from geophysical observations of seismic structure and the geoid, and geochemical observations of isotopes in basalts at mid-ocean ridges and ocean islands. This is a major discrepancy in our understanding of mantle dynamics and evolution. The work will involve the calculation of mass transport, stirring and deformation in simple convective systems that incorporate lithospheric plate motions, evolution of plate geometry, viscosity variations with depth, as well as rheological heterogeneities. The proposed work will evaluate these effects and assess the likelihood that such processes can account for the diverse geophysical and geochemical observations.
