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The Uinta Mountains in northeastern Utah and northwestern Colorado are among the rare major structures in the western United States with east-west trends.
The east-west trend may have an ancestry in a Precambrian aulacogen and a lower Paleozoic arch. The area was quiescent until the Paleocene or Eocene when the mountain block began to rise and the basins on the north and south subsided. The mountain block cuts across north-south-trending arches formed during the Cretaceous, and it uplifted the belt of Sevier-Laramide overthrusts. The eastern part of the mountain block collapsed during the mid-Tertiary.
The range is an anticline with a core of Precambrian metasediments and steeply dipping Paleozoic and Mesozoic rocks on the flanks. Tertiary debris from the mountains overlaps onto older rocks.
Anticlines along the flanks of the mountains produce oil and gas from Paleozoic and Mesozoic rocks. Stratigraphic traps on the structures cut by the mountain block are enhanced by the intersection, and they produce from Cretaceous and Tertiary rocks. Uplift of the mountains was important in creating unconformity and stratigraphic traps in several oil and gas fields and in bituminous sand deposits.
Geophysical work and drilling have shown the flanks of the mountains to be thrust over or to overhang the adjacent basins.
The numerous structural intersections, overhanging flanks, and the facies changes caused by the Uinta Mountains provide good opportunities for continued exploration and success.
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