Timing and structural interaction between the thrust belt and foreland, Hoback basin, Wyoming

Detailed geologic mapping and structural analysis along the northeast margin of the Wyoming overthrust belt reveals a complex interaction between the thrust belt and foreland faults and folds. Palynologic dates and structural overprinting provide the primary age control for the timing of these events: (1) late Cretaceous to early Paleocene motion on the east-directed Granite Creek thrust; (2) middle to late Paleocene movement on the east-directed Granite Creek blind thrust and the genetically related (by triangle zone) west-directed Game Hill thrust; (3) possibly early to late Paleocene motion on the foreland Cache Creek fault system on the Cache Creek “blind” fault; (4) late Paleocene to early Eocene motion on the out-of-sequence, east-directed Prospect thrust system; (5) early Eocene motion on the foreland Cache Creek subfault and Cache Creek fault of the Cache Creek fault system; and (6) late normal faulting, which truncates the above structures. Thrusts within the out-of-sequence Prospect thrust system include, from east to west, the westward-younging Cliff Creek, Little Granite Creek, Bull Creek, Game Creek, and Bear thrusts. The evolving Gross Ventre foreland uplift provided a buttress against further eastward thrusting, thus primarily causing this westward-younging thrust sequence.