Early Eocene sedimentary rocks in SW Oregon offer an ideal opportunity to test models for the surface response to collision of the oceanic Siletz terrane with western North America, and regional post-collision adjustments, that affected the PNW region between ~ 55 and 40 million years ago.
The events associated with collision of Siletzia are central to understanding the origins of the Coast Ranges in western Oregon and Washington, and crustal structure that governs processes in the modern Cascadia subduction zone. The results of our study will generate new insights into the surface response to collision-related mountain building and post-collision reorganization associated with this major terrane-accretion event.
This research applies a novel combination of field and analytical techniques including sandstone petrography, detrital zircon dating, Hf isotope analyses, Ar/Ar dating of detrital micas, and detrital thermochronology, all tied to detailed geologic mapping and stratigraphic analysis. The study provides a unique opportunity for students to conduct place-based research by investigating the deep-time geologic history of Oregon. Local communities benefit through collaboration, team teaching, and sharing of data and resources among the University of Oregon, Oregon State University, Lane Community College, and the Oregon Department of Geology and Mineral Industries (DOGAMI).