Early Cretaceous deposition in the western Wyoming, eastern Idaho, and northeastern Utah region reflects the interplay of tectonic and eustatic controls during the early development of the thrust belt in this area. A major marine withdrawal at the close of the Jurassic was closely preceded by initial movement of the Paris-Willard thrust. Two subsequent pulses of eastward movement along this thrust occurred: a poorly dated event in Early Cretaceous time and a final movement during Late Cretaceous (Turonian). These periods of uplift on the western margin of the foreland basin are reflected by the eastward progradation of coarse fluvial clastic wedges into the Cretaceous seaway.

Between pulses of thrust movement, tectonic quiescence was coupled with a decrease of clastic influx into the subsiding basin. During periods of marine regression, broad marl-dominated lacustrine depositional systems developed in the foreland basin. In contrast, during transgressive periods, depositional environments were characterized by mixed fluvial and lacustrine systems bordered down paleoslope by extensive marsh-dominated systems. Basin subsidence, instigated by tectonic loading of the Paris-Willard thrust allochthon and further enhanced by sediment loading of the coarse clastic wedges, controlled the distribution of lacustrine systems during periods of marine regression.

The Paris-Willard thrust allochthon throughout the Early Cretaceous was dominated by upper Paleozoic strata. Subsequent to the final movement of the thrust, the allochthon was carried passively eastward and uplifted by ramping along steps of the more eastern Absaroka thrust. This uplift resulted in the exposure of upper Precambrian and lower Paleozoic strata which dominate the allochthon today.

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