Mantle Convection with Plates and Mobile, Faulted Plate Margins

Shijie Zhong and Michael Gurnis

Seismological Laboratory, 252-21, California Institute of Technology, Pasadena, CA 91125

A finite element formulation of faults has been incorporated into time-dependent models of mantle convection with realistic rheology, continents and phase changes. Realistic tectonic plates naturally form with self-consistent coupling between plate and mantle dynamics. Following the initiation of subduction, trenches rapidly rollback with subducted slabs temporarily laid out along the base of the transition zone. Following slab penetration into the lower mantle, the velocity of trench migration decreases markedly. The inhibition of slab penetration into the lower mantle by the 670-km phase change is greatly reduced compared to models without tectonic plates.