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Abstract: Provenance, Geometry, Depositional Facies, and Age of the Upper Cretaceous Wahweap Formation, Cordilleran Foreland Basin, Southern Utah

POLLOCK, STONNIE L., New Mexico State University, Dept. of Geological Sciences, Las Cruces, NM

The Wahweap Formation, exposed along the flanks of the southern High Plateaus and the Kaiparowits Plateau of Utah comprises 360-460 m of interbedded conglomeratic sandstone, sandstone, and shale. During the end of the Campanian, Wahweap strata were deposited by fluvial systems within a subsiding foreland basin. Preliminary petrographic analysis of Wahweap sandstones suggests that detritus was derived from both the Mogollon highlands and the Sevier thrust belt. Like other Upper Cretaceous sandstone bodies to the north, the upper part of the Wahweap, Formation appears to form an extensive sheet of sandstone of relatively uniform thickness across the foreland basin.

The purpose of the proposed research is to determine the provenance, geometry, depositional facies, and a better age constraint for the Wahweap Formation. This research also seeks to test previous workers' correlation of the Wahweap Formation with the Castlegate Sandstone. Geologic investigation of the Wahweap is being achieved by the following methods: 1) Measurement of stratigraphic sections to determine thicknesses and depositional facies; 2) petrographic analysis of field samples for sandstone detrital modes and provenance; 3) paleocurrent analysis to delineate source area; 4) palynological analysis for age.

This research will help refine biostratigraphic age constraints and enable more precise correlations with other Upper Cretaceous Formations such as the Castlegate. Improved correlation may permit better understanding of the origins of large-scale stratigraphic architecture in this foreland basin. Interpretation of the depositional facies, geometries, and provenance of the Wahweap will also provide a better understanding of foreland-basin dynamics and Late Cretaceous paleogeography.

AAPG Search and Discovery Article #90931©1998 AAPG Foundation Grants-in-Aid