Geologic History of Site of Uinta Basin, Utah

Abstract

The Uinta basin in northeastern Utah includes an area of 9,300 square miles and is a typical Rocky Mountain asymmetric basin. It developed during early Tertiary time and contains up to 18,000 feet of lower Tertiary fluviatile and lacustrine deposits. The configuration of the basin, which persists as a topographic depression, is controlled by pre-Tertiary structural trends. Oil and gas accumulations are situated in response to these structural trends and their effect on Tertiary sedimentation. Mississippian and Cambrian marine transgressions from the west caused deposition of sandstone and limestone in the Uinta basin area. Pennsylvanian orogeny uplifted the northwest-trending Uncompahgre Mountain Range in the southern part of the area, and conglomerate near the uplift grades northward into finer clastics and limestones. Permian through Jurassic deposits represent four major marine transgressions from the west and intertongue eastward into thinner, non-marine strata and overlap the Uncompahgre Mountain Range. During Cretaceous time the area was part of the Rocky Mountain geosyncline and received 6,000-12,000 feet of Mancos shale and Mesaverde sandstones derived from a major sources that was elevated in the west. Tertiary regional uplift of western United States elevated the rims of the Uinta basin more than the central part, creating the basin. The rims are largely pre-Tertiary structural blocks of various ages which were strong or buoyant enough to respond to the uplifting.