Evolution of Resource-Rich Foreland and Intennontane Basins in Eastern Utah and Western Colorado: Salt Lake City, Utah to Grand Junction, Colorado, July 20-24, 1989

Upper Cretaceous and lower Tertiary rocks in central and eastern Utah record the transition from deposition in a marine foreland basin, bounded on the west by a thrust belt, and deposition in a regionally extensive set of continental intermontane basins. Similar structural domain-linked rock sequences characterize much of the eastern Cordillera of the United States and Canada, but the timing of events and the local structural and depositional style vary from area to area. The formation of these foreland and intermontane complexes has given rise to a remarkably diverse and extensive complex of energy and mineral deposits whose occurrences commonly are depositionally controlled.

In Utah, Albian(?) to late Campanian tectonism characterized by thrust faults and coeval folds and synorogenic sedimentation in a marine foreland basin is a part of, and coincident with, the Cretaceous Sevier orogeny of Armstrong (1968) (fig. 1). Rocks reflecting these sedimentologic and structural characteristics are commonly referred to as having resulted from "Sevier-style" tectonism and sedimentation. The development of a large internal drainage system or a series of local basins bounded by faults of varied types is used to indicate new or renewed uplift on structural elements far to the east of the thrust belt, and movement in the thrust terrain, that segmented the foreland basin (fig. 2). The local uplift and intermontane system in this area is characteristic of "Laramide-style" tectonism and sedimentation (Fouch and others, 1983) which, in the Guide area, extended from late Campanian/early Maastrichtian to late Eocene/early Oligocene(?) time. The term "Laramide" has been variably applied for many years for Upper Cretaceous to Eocene tectonism and synorogenic rocks of similar origin in the Rocky Mountains and is commonly used in the region's literature.