Archean zircons in Cretaceous strata of the western Canadian Cordillera: The "Baja BC" hypothesis fails a "crucial test"

The magnitude of late Mesozoic terrane translation along the western North American continental margin is controversial. paleomagnetic data suggest mo re than 3000 km of dextral displacement of the Insular superterrane and ass ociated assemblages between ca, 74 and 50 Ma. Conversely, geologic evidence is more compatible with less than 500 km of offset during this time. Preca mbrian cratonic rocks older than 25 Ga are restricted to northern latitudes (above 40 degrees N) in North America, and the presence or absence of Arch ean zircons within easterly derived Cretaceous strata has been proposed as a "crucial test" of the major translation hypothesis, There is no plausible source of Archean and Early Proterozoic zircons found in the Queen Charlot te, Nanaimo, and Methow basins other than the Canadian Shield or closely as sociated Proterozoic strata, The coexistence of Archean-Early Proterozoic, Middle Proterozoic (1.5-1.6 Ga) and Mississippian detrital zircon in these basins indicates deposition in northern latitudes, incompatible with the Ba ja B.C. hypothesis.