GEOMORPHOLOGICAL AND GEOPHYSICAL EVALUATION OF QUATERNARY INTRAPLATE DEFORMATION IN THE NORTHERN WIND RIVER BASIN, WYOMING

The Stagner Creek Fault, near the southern margin of the Owl Creek Mountains is one of a handful of WNW-ESE striking faults in central Wyoming that exhibit quaternary activity. These faults are generally believed to be normal faults, but the geometry and kinematic behavior of the Stagner Creek Fault is not well defined – a previous shallow seismic investigation suggested the surface scarp may result from a north-dipping, reverse fault. In a regional tectonic context, these faults are nearly orthogonal to the orientation nearby Basin and Range extension. This study aims to refine understanding of the geometry, orientation, and sense of movement on the Stagner Creek Fault through shallow seismic reflection imaging. Two shallow seismic reflection profiles have been acquired. The first seismic reflection profile invovles short fixed spread line in order to attain high-resolution imagery of the upper portion of the fault and accurate seismic velocity control to improve upon the previous survey. The second seismic reflection profile is approximately 500 meters away from the first, and aims to reach a greater depth than previously imaged, through the use of a substantially longer rolling spread acquisition strategy. The second profile also provides constraints on the true fault geometry. Additionally, this study also improves the detailed micro-topographic mapping and geomorphic mapping of deformed, late Quaternary alluvial surfaces through the application of low-altitude aerial surveying. Re-assessing the late Quaternary behavior of the Stagner Creek Fault may help improve the understanding of the regional earthquake hazard for local infrastructure, particularly the Boysen Reservoir.