Abstract
The Permian White Rim Sandstone in the Elaterite basin (Canyonlands National Park) exhibits an unusual paleotopographic relief. The mapped portion of the exposed top of the formation indicates that the paleotopography has a prolate configuration in plan view. The major axis and crest of the relief trends N09°E. In cross section, the paleotopography is convex upward. The flanks of the structure are slightly terraced with two main levels. Dip angles on the flanks range from 0° to 16°, with the more gentle slopes located toward the crest of the topographic high and generally steepening as the structure disappears into the subsurface. The sedimentary structures and stratigraphy in the 1-5.3 m (3-17.4 ft) upper veneer of the White Rim Sandstone indicate that the topography was affected by marine wave processes in the Elaterite basin. Small-scale features in the basal contact of the veneer include scours up to 15 cm (6 in.) deep, sharp steplike cuts up to 45 cm (18 in.) deep, and rip-ups of the lower eolian part of the White Rim Sandstone averaging 30 cm (12 in.) in diameter. Lateral changes in structures and lithologic characteristics indicate that southwest of the Elaterite basin the veneer was deposited in a fluvial environment. The form of the paleotopographic high in the Elaterite basin is practically inherited from an eolian dune field. The uneven base and presence of chert pebbles in the veneer indicate erosion of Permian highs and an unconformable contact between the lower eolian and upper veneer of the White Rim Sandstone. Deposition of the veneer and partial reworking of the topography occurred during a marine transgression at the Permian-Triassic boundary. End_of_Article - Last_Page 938------------
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