The Cascadia convergent margin in northwest Washington State marks the subduction boundary between North America and the Juan de Fuca plate. The Olympic mountains consist of an assemblage of Eocene to Miocene thrusts structurally overlain by Eocene basalts and Eocene to Miocene clastic rocks. Uplift of these rocks occurred during the late Miocene. These observations and available fission track data have resulted in a tectonic model involving accretion and underplating followed by uplift while accretion continues. This project will test between two end-member explanations for the timing and style of the uplift, simple doming or large scale normal faulting. Methods include fission track dating and structural analysis. Results should help understanding causes of uplift in active convergent orogens.
