How a subducting plateau impacts regional and global tectonics?

<p>Plateau subduction is a common process at different plate convergent margins, and they often modify subduction and affect slab behaviour. However, fewer studies have been conducted in the intraoceanic subduction context, and the physical and rheological parameters involved imply a strong hypothesis on the initial conditions (thermal state, no flow in the mantle, no interaction with the tectonic network). Here, we use global three-dimensional spherical mantle convection models to investigate the potential impacts of a subducting plateau on subduction zones and plate reorganization from regional to global scales in a fully self-consistent plate-like tectonics system. Our models show that plateaus with different sizes (length, width and thickness) can locally slow down the trench retreat rate. A larger plateau prevents trench migration, eventually terminating the subduction. The buoyancy of plateaus is found to influence the shape of the trench. Low buoyancy plateaus do not deform the trench as they subduct while in models with buoyant plateaus, the trench advances landward in front of a plateau forming an arcuate shape in the map. This arcuate shape of the trench is further enhanced with decreasing buoyancy and increasing viscosity. If the oceanic plateau has a higher yield stress, it will always drive the formation of the arcuate trench before fully subducted, regardless of the buoyancy. The simulations suggest that any single plateau rheology variable (buoyancy, or yield stress) except the viscosity can influence trench migration behaviour on a regional scale. We will also explore how plateau subduction modifies the global tectonic evolution over 100 My.</p>