THE EFFECTS OF PLATE COUPLING ON DYNAMIC TOPOGRAPHY AND SUBDUCTING PLATE VELOCITY: INSIGHTS INTO OCEANIC PLATEAU SUBDUCTION

Properties of subducting slabs can have a first order control on the surface deformation of overriding plates. For example, the subduction of a shallow plateau can result in an increase in coupling between the downgoing and overriding plates. In the Alaska subduction zone, which is accommodating convergence between the Pacific and North American plates, the oceanic Yakutat plateau is currently colliding with the plate boundary and subducting beneath North America. As a first step in understanding the dynamics of oceanic plateau subduction, a set of two-dimensional (2D) geodynamic models using a non-Newtonian rheology investigate the effects of slab dip and the degree of interplate coupling on dynamic topography and subducting plate velocity. These results show that an increase in plate coupling reduces the subducting plate velocity and can lead to an increase in uplift on the overriding plate accompanied with deformation moving further inland. As a first step in implementing the Yakutat plateau into geodynamic models, we have also constructed a three-dimensional (3D) configuration of the Yakutat plateau based on geological and geophysical constraints. The 3D configuration shows the geometry of the modern Yakutat plateau as well as its relation to the subducting Pacific plate and highlights the complexities associated with adding realistic properties of geologic structures into 3D computational models.