In western Utah, large-scale older-over-younger thrusting and folding occurred along the northeast-trending Sevier orogenic belt (Armstrong, 1968a). Sevier deformation has been described primarily in western Utah and was extended by various early workers into the eastern and southern portions of Nevada. The timing of Sevier thrusting is poorly constrained, but appears to have been initiated by the Middle-Jurassic in southeastern Nevada. Total tectonic shortening across the Sevier belt is estimated at perhaps 40 to 60 miles, with individual major thrusts commonly displaying 10 to 20 miles of displacement (Armstrong, 1963).

The distribution of Sevier structures is poorly understood in northeastern Nevada. The analysis done during this study suggests that there is little in the way of demonstrable Sevier thrusting in northeastern Nevada. Most of the low-angle faults originally attributed to Sevier thrusting in northeastern Nevada are actually younger-over-older low-angle normal faults which attenuate rather than repeat stratigraphic section. It seems clear that some of the Cenozoic low-angle normal faults are at least partially reactivated Mesozoic thrusts which are probably related to Sevier deformation. Still, major thrust faults with tens of miles of horizontal displacement are simply not present in northeastern Nevada.

Minor thrusts with less than 2 miles of displacement are present in various ranges including the Pancake and Antelope Ranges, and may represent local vestiges of Sevier thrusting. Preliminary work by Bartley and others (1985) and Fryxell (personal communication, 1985) suggest that the Sevier belt may reach into the northern Quinn Canyon and southern Grant Ranges as well. Thrusts placing Cambrian and Lower Ordovician Limestones over the Devonian Guilmette are present in the Sawmill and Hooper Canyon areas of the northern Quinn Canyon Range and adjacent areas of the southernmost Grant Range. The age constraints on this thrusting remain fairly loose. In at least one place the Oligocene Currant Tuff unconformably overlies a thrust placing an upper limit on the deformation.

It is important to note that apparent older-over-younger thrust relationships can also be generated locally along low-angle normal fault systems. This is particularly true in areas where several low-angle normal faults of various ages intersect one another. This kind of faulting exists in nearly all of the areas where local thrusts with minor horizontal displacements have been noted in northeastern Nevada. This suggests that even the local "thrust" relationships may be extensional rather than compressional in origin.

It appears that much of northeastern Nevada is within the hinterland of the Sevier belt and retains little of the compressional Mesozoic overprint obvious to the southeast in western Utah and southern Nevada. Instead this hinterland is marked by relatively intact broadly arched and folded ranges and major monoclinal fault blocks adjacent to structurally thrashed terrane characterized by low-angle normal fault denudation.