Plate Motions in 3D Cartesian Convection: The Role of Internal Heating and Plate Reorganization

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KingEAR-0207222The investigators have documented a mode of convection in both 2D and 3D Cartesian convection calculations with mobile plates where the plate motion changes on a time scale comparable to the time scales of plate reorganizations observed on Earth. This proposal will further our understanding of coupled plate-mantle convection. Over the past few years, the field has developed a substantial understanding of the interaction of geometrically fixed plates and mantle convection; and it is appropriate to consider calculations where the plate boundaries evolve with time. It is proposed to use a yield-strength constitutive-law rheology in a series of calculations using the aspect ratio, Rayleigh number and internal heating values used in the plate reorganization studies by Lowman, King and Gable (2001, submitted). There are two specific questions that this proposal will address: When plate boundaries are allowed to evolve dynamically in the yield-strength rheology calculations, are the rapid plate reorganizations that we have seen in previous calculations accompanied by changes in plate boundaries? Second, under what conditions (i.e., what activation energies and critical yield-strengths) are the constitutive-based plate methods able to produce plate-like surface velocities during and after a plate reorganization event?