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Mississippian, Pennsylvanian, Permian and Lower Triassic strata in the eastern Great Basin aggregate almost 12,250 m (40,000 ft) of dominantly marine clastics and carbonates that accumulated in the eastern part of the miogeosynclinal belt of the Cordilleran geosyncline. Subsidence and hypersubsidence created depocenters in the Oquirrh, Sublett, Arcturus, Park City, Bird Spring and other sedimentary basins within this region. Late Paleozoic (Antler and Sonoma) and early Mesozoic (ancestral Sevier) tectonism within and west of but adjacent to the miogeosynclinal belt controlled contrasting realms of clastic and carbonate sedimentation within and near these basins. Various highlands in western and northwestern Utah, in eastern and northeastern Nevada, in southern Nevada, and in orogenic belts (Antler and Sonoma) lying still farther west were stripped, in some instances into their Precambrian cores, to provide some sediment to the adjacent mobile depocenters. The Emery, Uncompahgre, and Kaibab uplifts southeast of the miogeosynclinal belt also were source areas at times. However, the continental craton to the east and northeast provided most of the sediment which makes up the abnormal thickness of clastic strata in the basins described. Sediment derived from Precambrian and younger rocks in Wyoming, Montana, and Alberta was transported southerly, then westerly, and dumped into the various depocenters.

Although the Sonoma orogeny was a major tectonic event farther west during Late Permian and Early Triassic times, the transition from Permian to Early Triassic was not marked by major deformation in the eastern part of the miogeosynclinal belt Only a paraconformity marks the Permian-Triassic boundary at many places in the miogeosynclinal belt, although significant disconformities are present locally. Up to 1225 m (4000 ft) of Lower Triassic sediments accumulated during the waning stages of deposition, but by mid-Triassic time a major tectonic reversal occurred. The region that had been a negative mobile belt since late Precambrian time was then uplifted, whereas the region east of the Las Vegas-Wasatch hinge line became negative, and the hinge line was the fulcrum. The Cordilleran geosyncline was destroyed before the end of the Triassic, and throughout much of the Late Triassic, Jurassic, and Cretaceous some of its sediments were stripped away, to be recycled and deposited in the Rocky Mountain geosyncline to the east. The tectonic behavior of the Las Vegas-Wasatch hinge line thus controlled sedimentation over a large region throughout Paleozoic and Mesozoic time.

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