During Mesozoic and Tertiary time the western margin of North America developed by the accretion and rearrangement of numerous fault-bounded blocks or terranes. Detritus shed from these blocks accumulated in basins and may record some of the history of this tectonism. This project will address several questions by use of Sm-Nd and U-Pb isotopic studies of Mesozoic sequences in northern Washington State and southern British Columbia, including determining when the terranes arrived and began to contribute detritus to the basins and whether the volcanic activity recorded in the basins reflects oceanic or continental margin volcanic arcs. Results are expected to provide new insights to the tectonic development of northwestern North America and to further demonstrate the utility of this technique.
