MAPPING IN MOAB, UTAH REVEALS UNRECOGNIZED FAULT STRANDS AND BASIN FILL DEPOSITS RECORDING LATE QUATERNARY SALT DEFORMATION

Moab-Spanish Valley, Utah is a collapsed salt-cored anticline that is actively deforming due to salt dissolution and evacuation. In the 1960’s and 1980’s, Quaternary researchers first hypothesized that surficial deposits within the valley were deformed by salt subsidence. Recent studies with geochronologic tools have quantified rates of deformation within the city limits of Moab using the surficial deposits as markers of deformation across the Kayenta Heights fault zone. The presence of a bedrock arch between the subsidence centers of Moab and Spanish Valleys, along with an incised bedrock reach of Pack Creek along the Kayenta Heights fault zone suggest the patterns of faulting and subsidence are more complicated than previously recognized. This study aims to document spatial patterns of subsidence, faulting, and incision across the bedrock arch by surficial mapping at 1:6000-scale utilizing VrTwo photogrammetry. OSL dating of key surficial deposits provides the necessary age control to quantify subsidence rates. Results indicate the Kayenta Heights fault zone is wider than previously recognized. Pack Creek runs parallel to the Kayenta Heights fault zone effectively concealing a portion of the fault, and resulting in previous researchers having missed up to 500 meters of offset. Along entrenched Pack Creek, the existence of a knickpoint through the arch may also mark active faulting. To the northwest flank of the bedrock arch, previously unrecognized Pleistocene basin fill deposits are exposed recording late Quaternary subsidence of Moab Valley. This unrecognized, late Quaternary deformation highlights active hazards within the town of Moab, Utah.