Investigating the Effect of Mantle Flow on Surface Deformation in Alaska, Northwestern Canada, and the Bering Sea Using 3-D Geodynamic Models

This research aims to examine the effect that mantle tractions have on surface deformation throughout the Pacific-North America plate boundary zone in Alaska, western Canada, and the Bering Sea region. We use 3-D geodynamic models to simulate the crust and upper mantle in order to investigate the tectonic force balance between plate boundary interactions, gravitational collapse, and basal tractions. We determine that mantle tractions with a magnitude of ~2.5-3.8 MPa, directed to the southeast, in conjunction with forces from the Yakutat flat slab, best fit the steady-state plate motion estimates in Alaska. We also show how these mantle tractions have likely aided in concentrating deformation to the northwest of incoming Yakutat oceanic plateau throughout the ~50 Ma evolution of flat slab subduction in this region. Finally, we conclude that mantle tractions also impact the broad zone of distributed deformation surrounding the Bering Sea. The confluence of basal forces and tectonic extrusion, due to the Yakutat flat slab, may lead to the evolution of a new plate boundary extending from northwest Alaska to the Kuril-Kamchatka subduction zone.