Timing of Deformation in Overthrust Belt and Foreland of Idaho, Wyoming, and Utah

ABSTRACT A review of the timing and displacement evidence of the major structures of the western Wyoming Overthrust belt and foreland shows there is a progression in thrust displacement, apparent duration of motion, and palinspastic position of thrust traces from west to east. Those toward the west moved farther for an apparently longer period of time and are more widely spaced in their restored positions than those toward the east. However, average thrust velocities are all on the order of 0.5 ± 0.5 cm/yr (0.2 in./yr). Foreland events are in part synchronous with thrust belt events and had an effect on them. Although dating precision varies widely on major normal faults, present evidence does not contradict the generally held view that all normal faults postdate the youngest thrusting.