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A comprehensive stratigraphic analysis of the Palo Duro basin, emphasizing facies and depositional systems, provides a framework for resource analysis and exploration. A pre-Pennsylvanian section consists of thin, basal, Cambrian sandstone overlain by Ordovician and Mississippian shallow-shelf carbonate rocks. Pennsylvanian and Lower Permian rocks consist of 1,000 m of basin and slope shales, massive shelf-margin carbonate rocks, and deltaic sandstones. Facies distributions define a major episode of basin subsidence and transgression (Pennsylvanian) with shelf-margin retreat, followed by regression (southward), and basin filling (Early Permian). In Late Permian time, the basin was an extensive sabkha-shelf platform on which salt (upper sabkha), anhydrite-gypsum (lower sab ha), dolomite (subtidal to intertidal shelf), and red beds were deposited. Two continuous 1,220-m cores drilled to the base of the evaporites provide a unique opportunity for calibration of well logs with petrographic studies, and for resource evaluation (fluid tests, uranium and copper analyses, etc).
The subsurface analysis has been coordinated with geomorphic and hydrologic studies in the same area (climate, slope, stream, and eolian process monitoring and field surveys of selected drainage basins) to demonstrate surface and subsurface interrelations. For example, locations of salt solution zones in the evaporite section coincide with surface erosional features, suggesting control of solution rate and position by drainage. High solute loads of area streams are probably derived from subsurface evaporite solution and result from regional surface discharge of groundwater circulation systems.
Lack of proven oil and gas reserves in the basin may be attributable to a limited volume of thermally mature source rocks.
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