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The units studied have been assigned to two groups, the Winterburn group and the overlying Wabamun group.
Normal Marine episode
Biostromal and Evaporite episode
The Winterburn group reflects two sedimentary episodes. The lower of these episodes embraces, in turn, two phases. The initial phase consists of the formation of biostromes in the form of shoals in the more basinal portion of the area. On the south, stratigraphically equivalent deposits on the shelf area are characterized by a series of beaches and bars of bioclastic material. This first phase is governed by the termination of the tectonism which prevailed during deposition of the underlying Woodbend sediments. The overlying deposits, which consist of evaporites and carbonates, form a second phase that marks the initiation of a tectonically and environmentally controlled restriction of sedimentation which remains evident during most of the remainder of Devonian sedimentation.
Clastics in the form of sand, silt, and shale were supplied to the area during the second episode of Winterburn time. The amount of clastic material, diluted to varying degrees with carbonates, and evaporites, is quantitatively not great except in those areas which were presumably nearest to two separated source areas. Evidence is present of a clastic depositional basin marginal and west of the intracratonic evaporite basin.
The evaporite deposits of the basal unit of the Wabamun group constitute by far the greatest thickness of strata studied. Post-depositional solution of the extensive salt and anhydrite deposits make necessary reconstruction of both isopachous and lithofacies maps. The thickness and patterns of sediments in the west suggest a tectonic and environmental history wherein the major factor in the restriction of the evaporite basin is a carbonate buildup which is petrographically and physiographically similar to the Bahama Banks.
The uppermost unit of the Wabamun in the area signals a return to normal marine and unstable shelf conditions--a forerunner for the deposition of the shales of the overlying Mississippian.
Prospective horizons for hydrocarbon accumulation occur at the transition between the Wabamun "Banks" and the evaporite basin, and in the organic deposits of the lower Winterburn.
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