GEODYNAMIC CONSTRAINTS ON TERRANE ACCRETION ALONG THE WEST COAST OF NORTH AMERICA

The accretion of exotic terranes and their translation along the west coast of North America have fundamental implications on the growth of continental crust. Structural geology, paleomagnetic data, and seismic tomography illuminate on this process with variable constraining powers. However, the exact nature and evolution of terrane accretion remain unclear, so does its relationship with Mesozoic-Cenozoic surface geology of North America and with the history of subduction. Here I discuss potential geodynamic constraints on terrane accretion by summarizing recent works on modeling subduction and resulting surface tectonic evolution. In particular, I will focus on 1) possible time windows for terrane accretion, 2) accretion mechanisms involving different subduction polarities, and 3) relevant surface geology records. I attempt to address these questions in the context of past plate motion and subduction, resulting present-day mantle structures, and various surface expressions. Key observational records that may be useful include the continuous westward movement of North America since Early Cretaceous, the Cretaceous-aged Western Interior Seaway (WIS), latest Cretaceous-early Tertiary Laramide orogeny, and present-day complex mantle seismic images beneath North America.