The Sensitivity of Core Heat Flux to the Modeling of Plate‐Like Surface Motion

Abstract

AbstractThe generation of a magnetic field and the presence of tectonic plates are fundamental aspects of Earth's evolution. Viable dynamic models of terrestrial mantle convection therefore require the existence of heat transport from the core and a surface characterized by piecewise uniform surface velocity domains (i.e., plates). To test the compatibility of these two requirements, we varied energy input, rheology, and compositional heterogeneity in more than 70 mantle convection simulations. Calculations are performed in a spherical annulus geometry. By systematic investigation, we demonstrate that Earth‐like core heat flux can be obtained with self‐consistent model plates. We find that, given an initial condition where model parameters are chosen to ensure a mobile surface, the mobility is not strongly influenced when H is varied by up to a factor of three. Consequently, in spherical models with steady core temperatures and internal heating rates, the latter quantity can be used to regulate core heat flow to fit within the bounds inferred for terrestrial values. In contrast, core heat flow is strongly sensitive to model yield stress. We systematically vary thermal viscosity contrast, an intrinsic depth‐dependent viscosity and the depth‐dependence of a stress‐dependent rheology and analyze how each factor affects both surface velocities and core heat flux. Finally, we show that the addition of an intrinsically dense component comprising 5% or less of the mantle volume does not affect surface mobility or plateness, although it can have a profound impact on heat loss from the core.