Provenance of the Paleogene Colton Formation (Uinta Basin) and Cretaceous–Paleogene provenance evolution in the Utah foreland: Evidence from U-Pb ages of detrital zircons, paleocurrent trends, and sandstone petrofacies

摘要

The fl uviodeltaic Colton Formation (LatenPaleocene–Early Eocene) forms a lobatendepositional system that prograded fromnthe south into the Laramide Uinta Basin ofnnortheastern Utah (United States) with a preservednsediment volume of ~3000 km3 and anmaximum thickness of ~1000 m. Joint considerationnof detrital zircon ages, paleocurrentntrends, and sandstone petrofacies permits annassessment of Colton provenance relationsnin the context of evolving Cretaceous–Paleogenensedimentation in the Utah foreland.nGrains with U-Pb ages younger than 285 Manderived from the Cordilleran magmatic arcnform ~50% of the detrital zircons in arkosicnColton sand, and were transported ~750 kmnto the Uinta Basin from the Mojave segmentnof the arc by the California paleoriver.nColton sedimentation was the Paleogenenculmination of a persistent pattern of Cretaceousnsediment transport northward, subparallelnto the Sevier thrust front, to supplementneast-directed sediment delivery to thenretroarc foreland from the Sevier thrust belt.nThe ratio of longitudinally to transverselynderived sediment was enhanced in forelandnstrata after Laramide deformation producednintraforeland uplifts that screened the forelandnbelt from Sevier sources. The relativenabundance of arc-derived detrital zirconsnthat were contributed to strata of the Utahnforeland increased in late Campanian timenand remained high into Eocene time. Detritalnzircon populations in Paleogene forearcnstrata of southern California are compatiblenwith coeval derivation of arc-derived detritusnin the forearc sands and the Colton backarcnsand from a common paleodrainage dividencrossing the Mojave region to connect hinterlandnNevadaplano and Mexicoplano uplandsnto the north and south.