The Cutler Formation is composed of thick, arkosic, alluvial conglomerate, sandstone, and mudstone shed southwestward from the Uncompahgre Uplift into the Paradox Basin. More basin-ward the Cutler is recognized as a group consisting of differentiable formations. Discrete formations historically have not been distinguished near the uplift, but this study identified several separate successions in the Richardson Amphitheater. Research at the Richardson Amphitheater, ~12 km southwest of the uplift and ~30 km northeast of Moab, Utah, led to a systematic subdivision of the Permian Cutler Formation proximal to the uplift. Likely driven by channel cutting and migration across the alluvial fan, six 10-20 m thick successions are partially exposed. The dominant observed facies are basal conglomerate and channel-fill trough cross-stratified sandstone overlain by finer-grained distal sheetflood and frequently pedogenically altered sandstone. Down-warping of identified successions and the presence of additional sands within the area of flexure suggest that localized salt withdrawal created a sediment depocenter in the Richardson Amphitheater, ~6 km northwest of the Onion Creek salt diapir. The identified salt withdrawal feature is more proximal to the Uncompahgre Uplift than any of the major documented salt structures in the area and was not previously documented. Six measured stratigraphic sections and hundreds of high-precision differential GPS data points outlining major lateral erosional surfaces form the basis for interpretation. Five mapped erosional surfaces (bounding surfaces based upon differential GPS point interpolation) are laterally extensive within the approximately one square kilometer study area, and as such, represent stratigraphically significant surfaces. Within the generated structural geocellular model, stratigraphic data from measured sections informed facies modeling between major surfaces. This outcrop model may serve as an analogue for subsurface systems deposited in similar settings.



College and Department

Physical and Mathematical Sciences; Geological Sciences



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Alluvial fan, arkosic facies, bounding surface, Cutler Formation, conglomeratic sandstone, digital outcrop model, fluvial, pedogenic carbonate, Richardson Amphitheater, salt tectonics, trough cross-stratified sandstone, Utah



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