Lower Paleozoic strata of the Roberts Mountains allochthon were derived both directly and indirectly from Precambrian basement rocks. The Upper Cambrian(?) Harmony Formation was derived directly from erosion of Proterozoic crystalline rocks along the western margin of North America. Zircon data from feldspar-bearing strata of the Vinini Formation (Lower Ordovician) suggest a provenance link with the Harmony Formation. Compositionally mature, Middle Ordovician eugeoclinal (Palmetto Formation) and miogeoclinal (Eureka Quartzite) quartzites exhibit similar isotopic signatures except that the miogeoclinal quartzite unequivocally contains an Archean component. Volcaniclastic sediment within the Slaven Chert (Middle Devonian) contains Precambrian zircon but no evidence of neovolcanic zircon. New U-Pb isotopic data for detrital zircon from the allochthon are most consistent with models of Antler orogenesis that do not require significant interaction (collision) of a fringing volcanic arc with the continental margin.