1. The White Rim Sandstone Member of the Permian Cutler Formation in Canyonlands National Park, Utah, was deposited in an eolian system.
2. The White Rim contains three types of eolian depositsdune, interdune, and sabkhawhich can be differentiated on the basis of sedimentary structures and petrologic features.
3. Distinctive sedimentary structures of the dune deposits are large-scale, unidirectional, tabular planar crossbed sets; high-index ripples oriented parallel to dip direction of the foresets; and raindrop impressions. A strongly unidirectional, northwest to southeast orientation of the crossbedding suggests the dune forms were barchanoid or transverse ridges. The dune deposits are basically light-colored, fine-grained, well- to moderately well- sorted quartz arenites with little clay material.
4. Interdune deposits resulting from both deflationary and depositional processes and formed under varying degrees of wetness are present. Most of the interdune deposits occur as thin, discontinuous units intercalated with the dune deposits. Dry deflationary deposits occur as darker colored, thin, lenticular, bimodal, coarse-grained lags between crossbed sets. Other interdune deposits appear to have formed by a combination of damp and evaporitic depositional processes. Characteristic sedimentary structures of these interdunes are wavy, discontinuous, horizontally laminated bedding with dark- and light-color banding; adhesion ripples; bioturbation; and desiccation polygons, which may represent relict salt ridge structures. Their basic texture and mineralogy are similar to the dune deposits, but the depositional interdunes contain abundant euhedral to subhedral dolomite rhombohedrons, fecal pellets, a fossil fragment, and concentrations of heavy mineral grains in laminations.
5. A detrital-dominant, inland sabkha formed downwind of the main White Rim dune field. This can be seen in the eastern part of the study area, where the entire lower portion of the White Rim is flat-bedded sandstone and has most of the characteristics of depositional interdune deposits. Location of this sabkha was topographically controlled by early movement of the Monument upwarp, and grew as the result of a stable and slowly rising water table.
6. The White Rim dune field was deposited in a coastal setting by northwest-to-southeast onshore winds during a period of marine transgression. Evidence for a coastal setting includes Permian paleogeography, stratigraphic relationships, geometry of the sand body and dune form, and certain petrologic features such as glauconite pellets, a crinoid fragment, and heavy mineral concentrations.
Last Updated: 09-Nov-2009