A rapid tectonic plate reorganization event dynamically modelled by subduction cessation

The linearity of current-day ocean floor fracture zones demonstrates the longevity of periods of relatively steady plate motion, characterized by little to very slow movement of the associated Euler poles that describe the motion of the plates on a spherical surface. However, the geologic record also holds evidence that periods of nearly steady plate motion have been interrupted by comparatively rapid plate reorganization events, occurring in less than 10 Myr, that are well described by considering the associated change in the history of the Euler vector directions and/or magnitudes of the affected plates. One category of proposals for the driving mechanism for plate reorganization events makes a case for deeper mantle derived forces instigating surface motion change. A key factor in starting the initiation of mantle driven plate reorganization events may be the mantle’s radiogenically derived internal heating, which acts to form unstable reservoirs of buoyancy below the oldest sections of a plate, adjacent to mature slabs. The potential for internal heating to produce focused hot parcels in the mantle, capable of disrupting the steadiness of convection patterns, was described in previous numerical studies of thermal convection in momentum free fluids. Determination of the degree of success of plate generation is dependent on identifying all potential plate boundaries and inverting the implied intra-plate velocities to test their agreement on a common rotation axis (i.e., the plate’s Euler pole). Here, we utilize an iterative method for implementing a previously described tool for identifying potential plate boundaries in the output of a 3D numerical model of mantle convection. Post-processing model output for a period simulating nearly 150 Myr of evolution we track the history of several neighbouring plates and find that they maintain rigidity well demonstrated by Euler vector fitting of the intra-plate velocities. We find that generally, as their sizes and position change, the plates exhibit motion that changes direction and magnitude slowly. However, we also find that steady evolution can be punctuated by major but relatively short duration reorganization events, that we identify as being driven by the impact of mantle internal heating on the loss of slab-pull at a mature convergent plate boundary.