More constraints on internal heating rate of the Earth's mantle from plume observations

Abstract

Our previous numerical studies of plume dynamics without secular cooling effects demonstrated that the internal heating rate of the Earth's mantle is constrained to be ∼70% by inferred plume heat flux and plume excess temperature in the upper mantle. In this paper, by integrating the secular cooling effects into the numerical studies, we demonstrate that the dependence of plumerelated observations on internal heating rate is not affected by secular cooling and that the plume-related observations are only dependent on the internal heating rate and insensitive to its partitioning between radiogenic heating and secular cooling, thus confirming the conclusions of ∼70% internal heating rate from our previous numerical studies. Furthermore, we present a new analysis to constrain the internal heating rate with the plume-related observations based on the energy balance of mantle convection. The analysis shows that the internal heating rate of the mantle has a lower bound of ∼60% to satisfy the energy balance of the mantle with current plume observations, which is consistent with the conclusions from our numerical studies. Copyright 2009 by the American Geophysical Union.