Subsurface facies analysis of Upper Permian evaporites and red beds of the Palo Duro basin, Texas, provides information important in evaluations for potential hydrocarbons, uranium, copper, and evaporite minerals. Cores, cuttings, and well logs were used for analysis. Stratigraphic units include the Clear Fork Group, Glorieta and San Andres Formations, and post-San Andres Guadalupian and Ochoan strata.

Evaporites and associated carbonate rocks show basinward

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(southerly) facies changes from supratidal to subtidal; facies exhibit many features of modern, low-relief, coastal sabkhas. Lithofacies include (1) salt formed in upper sabkha evaporating ponds, (2) lower sabkha anhydrite in bedded units, (3) supratidal to subtidal dolomite with nodular and bedded anhydrite, and (4) highly burrowed subtidal-shelf carbonates. Red beds occur as sheets (up to 300 ft or 100 m thick) of shale and fine sandstone, which intertongue basinward with evaporites and dolomite. It is suggested that these formed largely in tidal mudflats grading basinward into tidal sandflats. Clastic input was by eolian and/or low-energy alluvial processes. The genetic aspect of the stratigraphy is a general southerly facies shift through time.

Potential for potash minerals is best in the upper sabkha facies associated with salt, whereas anhydrite is abundant in the lower sabkha deposits. Copper may be present in the tidal-flat systems. Lack of large gamma ray anomalies suggests that ore-grade uranium concentrations are unlikely. Hydrocarbons are present in Guadalupian facies equivalents on the southern basin margin, and knowledge of facies relations will aid exploration.

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