The western margin of North America has experienced several episodes of tectonic activity, culminating in large-scale accretion of allochthonous terranes in the Mesozoic. The Kootenay Arc is an arcuate belt of Proterozoic to Jurassic rocks extending from east-central Washington to SE British Columbia. This study will examine and attempt to date the emplacement of early Paleozoic eugeoclinal sedimentary and volcanic rocks over Cambrian and older miogeoclinal rocks. Emplacement of the allochthonous rocks could have occurred either during the mid-Paleozoic Antler orogeny, or during Jura-Cretaceous accretion of outboard tectonic fragments. Results will have considerable impact on models of the tectonic evolution of the western continental margin of North America including indication of how close some of the allochthonous terranes were to the margin during the Jurassic and perhaps Paleozoic time.
