Structure Along the Arlington Fault Zone, Pass Creek Area, Southern Hanna Basin, Wyoming

Seismic and well data along the Arlington fault trend in the Pass Creek area of the southern Hanna Basin define a sharp, basin-edge flexure. Evidence for deeper faulting is equivocal. No faulting can be recognized on the logs or dipmeter in a well drilled through the steep dip zone, nor can the fault or no-fault situation be differentiated based on seismic evidence alone. However, it seems likely that thrust faulting exists at the deeper Precambrian basement level. The envisioned genetic sequence is one which, in response to regional compression, begins with development of an intra-basement thrust fault. The fault zone propagates upward under continued stress and attenuates into a sharp fold at shallower Cretaceous levels. The observed field structure has been easily duplicated in a corn starch-"Play-doh", thrust-fold model experiment under laterally directed stress.