Evolution of cordilleran foreland basins and basement uplifts in response to crustal imbrication and foreland partitioning, southwest Wyoming and northeastern Utah

Crustal shortening in the central Rocky Mountain foreland between Jurassic and Tertiary time accumulated as a result of plate convergence further west. It was accommodated by thin-skinned (Sevier-style) folding and faulting of the sedimentary cover and thick-skinned (Laramide-style) shortening of basement rocks, with basement structures spatially and temporally overlapping younger stratigraphic units. Sea-level changes and sediment influx added stratigraphic complexity.; In the greater Green River and Uinta basins, crustal shortening developed by three structural mechanisms: (1) basement uplift on reverse or thrust faults, (2) imbrication and tilt of discrete 100- to 300-km-long structural blocks, and (3) minor but significant long-wavelength crustal folding. Temporal tilting trends and apatite fission-track data show that Laramide-style crustal shortening began at 98 Ma. Imbrication of three crustal blocks (Wind River over Green River over Uinta basin) produced initial uplift in the Wind River Range and Uinta Mountains and foredeeps south of them. Back-thrust of the Uinta Mountains along the North Flank fault (83 Ma) deflected the greater Green River basin southward, contemporaneously with major structural partitioning and complex reorganization of tilting patterns within the basin.; Between 98 and 48 Ma, over 5.5 km of sediment accumulated in the greater Green River basin; over 7 km in the Uinta basin. Finite-length-plate flexural models most accurately reproduce sediment thickness profiles. About 60% accumulation was due to regional isostatic effects; 40% was due to flexural effects of over 12 km of uplift in the Uinta Mountains and over 14 km in the Wind River Range.; Sediment accumulation and dispersal were strongly controlled by foredeep location, regional tilt, and structural elevation of basin spill points. During deposition of the Fort Union and Wasatch formations, paleodrainages from the western greater Green River basin, Great Divide basin, and Piceance Creek basin merged near or at Washakie basin and continued to Hanna basin.; Laramide-style basement uplifts developed in a smooth and continuous process that began during the Sevier orogeny.