The influence of the transition zone water filter on convective circulation in the mantle

[1] The ‘‘transition zone water filter’’ model of mantle convection attempts to reconcile geochemical evidence for isolated mantle reservoirs with geophysical evidence for whole mantle circulation by decoupling incompatible elements from bulk mantle circulation via a melt layer above the 410 km discontinuity. This would result in a stratified heating distribution similar to layered convection models, but would permit bulk mass and heat transfer across mantle interfaces. Here we test the basic effect of the water filter mechanism on mantle flow, in particular to see whether it induces layered convection and/or strong upwelling plumes above strongly heated layers. We investigate the influence of ten likely heating distributions on the planform of convection. Excepting an extreme case where all heating occurs in the transition zone, convection is not significantly influenced by the heating distribution. For Earth-like internal heating, the flow is dominated by downwellings which extend across the entire model mantle, as in uniformly internally heated layers.