Many terranes in the North American Cordillera contain Paleozoic arc and basinal assemblages of uncertain paleogeographic origin. Standard facies and biogeographic analysis have not been able to conclusively separate those terranes that originated along the North American margin from those that experienced greater transport. This project will expand and develop a promising new technique to help fingerprint the source of detritus now found in these detrital zircons may provide a unique signature of major precambrian cratons that would allow the separation of locally derived terranes from long-traveled allochthonous ones. The work will consist of extensive sampling in several terranes in the Pacific Northwest and single-crystal zircon age determination. Results will help build a data base and will contribute to understanding the correlation, paleogeographic setting and displacement history of Paleozoic arc and basinal sequences along the continental margin.