U-PB ZIRCON GEOCHRONOLOGY OF LOWER JURASSIC AND PALEOZOIC STIKINIAN STRATA AND TERTIARY INTRUSIONS, NORTHWESTERN BRITISH-COLUMBIA

New U-Pb zircon ages are reported from western Stikinia. Devonian and Pennsylvanian ages of volcanic rocks at Oweegee dome confirm the prese nce of pre-Permian strata, and with Paleozoic and Triassic detrital zi rcons from Lower Jurassic sandstone, they help to demonstrate pre-lowe r Jurassic deformation and uplift. The absence of pre-Paleozoic inheri ted zircon from all samples is consistent with Nd-Sr isotopic data whi ch suggest that Stikinia consists mainly of juvenile crust. U-Pb ages for posttectonic intrusions suggest that structures in Skeena Fold Bel t in the Kinskuch area formed prior to Eocene time. Five ages for fels ic volcanic rocks from stratigraphically well-constrained upper parts of the Hazelton are are approximately 196-199 Ma and suggest near-cont emporaneity for cessation of volcanism in the areas studied. The Sinem urian or late Sinemurian - early Pliensbachian ages are older than pre viously reported U-Pb and biostratigraphic ages for presumed correlati ve rocks to the west, and westward-migrating volcanism is implied. Tog ether with Toarcian fossils from overlying sandstone, the new ages sug gest that a hiatus of moderate duration preceded regionally extensive sedimentation.