Modelling and Interpreting the Surface Evolution of the Earth in Terms of Mantle Convection: Global Implications of High Heat Flow at the Core-Mantle Boundary

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The ultimate goal of this proposal is a fundamental revision of our current understanding of how convection in Earth's mantle works and how this internal dynamics controls the surface geological evolution of the Earth. This admittedly challenging goal is motivated by recent developments from a wide range of fields that point to deficiencies in the current, widespread view that mantle dynamics is dominantly controlled by the subduction of cold lithosphere and hence that Earth's thermal evolution occurs mainly by 'top-down' cooling. New work on seismic tomographic inversions of 3-D mantle structure, incorporating constraints from geodynamics and mineral physics, coupled with very recent mineral physical results on high heat flow at the core-mantle boundary (CMB), and the latest interpretations of Cenozoic plate motions showing the lateral stability of Earth's most active oceanic ridge system (the East Pacific Rise) indicate that the current standard model is, at best, incomplete. There is therefore a pressing need to develop a revised model of mantle convection capable of satisfying the new findings. I therefore propose a program of research involving a 'bottom-up' approach, encompassing the entire depth-extent of the mantle. This work will focus on a number of objectives: (1) Mantle tomography - to significantly improve resolution of the 3-D structures in the lower-mantle below the Pacific Ocean where large-scale upwellings of hot mantle material have been predicted, (2) Thermal evolution - to understand how the evolution of Earth's interior is affected by strong upward heat transport in thermal plumes originating at the CMB, (3) Data assimilation - to obtain high-resolution, accurate reconstructions of thermal structure and mantle flow over the course of the Cenozoic era, and (4) Plate-tectonic evolution - to develop state-of-the-art mantle convection models with complex rheology that yield self-consistent plates dynamically coupled to underlying mantle. One of the most important objectives of this proposal is the training of highly qualified personnel. Their participation will be a key component of this effort to establish a comprehensive new view of the functioning of our planet's internal dynamics.