Geochronology and geochemistry of the Huntington Formation, Olds Ferry terrane, Blue Mountains province, northern U.S. Cordillera: Implications for accreted terrane correlation and assembly

Abstract The Olds Ferry terrane is the more inboard of two accreted volcanic arc terranes in late Paleozoic–early Mesozoic Blue Mountains province northern U.S. Cordillera. We present geologic, geochronologic, and geochemical data from volcano-sedimentary Huntington Formation that place within a firm temporal tectonomagmatic context, establish its identity as fringing along Triassic to Early Jurassic Cordilleran margin. divided into unconformity-bounded informal members: Norian (ca. 220 Ma) lower member comprising sequence mafic-intermediate volcanics, massive volcaniclastic breccias, minor carbonates deposited unconformably onto 237.7 Ma Brownlee pluton intruded by 210.0 Iron Mountain pluton; Rhaetian through Pleinsbachian (<210–187.0 upper composed conglomerates, abundant rhyodacite rhyolite effusive pyroclastic flows, interlayered sandstone turbidites, with angular unconformity member. An erosional hiatus regional tilting produced an separating overlying basal conglomerates Middle Weatherby Izee forearc basin transgressive onlap sequence. rocks are isotopically enriched relative depleted mantle coeval igneous outboard Wallowa terrane. A evolution radiogenic 87Sr/86Sr ratios (0.7036–0.7057) εNd values (+5.4 +3.1) volcanics suggests increasing involvement continental-derived material their petrogenesis. Precambrian xenocrystic zircons both strongly support proximal location cratonal North America during much history. chronology tectonostratigraphic architecture allows robust correlation other fringing-arc Canadian