F.A. Stoakes, 1992. "Wabamun Megasequence", Devonian-Early Mississippian Carbonates of the Western Canada Sedimentary Basin: A Sequence Stratigraphic Framework, Jack Wendte, Frank A. Stoakes, Clarence V. Campbell
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This sequence comprises a thick succession of shallow-water ramp carbonates assigned to the Wabamun Group of Famennian age (Figure 1). In southern Alberta the section becomes evaporitic and is subdivided into the Stettler and Big Valley formations. In this account the open-marine Big Valley Formation is grouped within the overlying Banff cycle of sedimentation and as such is detailed in the next chapter. To the north and west, in northeast British Columbia, the Wabamun interval has equivalents into the Tetcho and Kotcho formations which shale out into the basinal Besa River Formation.
The Wabamun cycle marks a reflooding of the WCSB following the Winterburn cycle of basin fill (Figure 2). At the initiation of this cycle the underlying Winterburn succession had infilled practically all of the existing topography throughout most of Alberta and northeast British Columbia. Consequently, the lack of any significant precursor topography, meant that the Wabamun megasequence preserves a rather monotonous succession of low angle, mud-dominated ramps. The exception to this is around the Peace River Arch which existed, at least initially, as an "island" in the Wabamun sea. Here a number of shallow, fringing platforms existed. The superposition of muddy ramp cycles makes discerning depositional patterns and lateral shifts of facies belts in the Wabamun relatively difficult other than at its distal prolongation in northeast British Columbia or its landward transition into evaporites in southeast Alberta (Figure 4). Examination of these areas reveals that the bulk of the Wabamun section comprises an initial transgressive phase and a subsequent regressive phase.
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Devonian-Early Mississippian Carbonates of the Western Canada Sedimentary Basin: A Sequence Stratigraphic Framework
The Devonian and early Mississippian strata in the Western Canada Sedimentary Basin include a wide diversity of shallow-water carbonate and basin filling carbonate, shale and evaporite facies. Of these, the large Devonian platform-reef complexes are the most spectacular. They occur in magnificent exposures in the Front Ranges of the Canadian Rockies and in the subsurface of Alberta. In the subsurface, these complexes pool many of the largest oil and gas accumulations in Western Canada. This short course is intended to provide a summary of Devonian and early Mississippian deposits in the subsurface of the Western Canada Sedimentary Basin. One of the major goals is to present the evolution of these strata in a sequence-stratigraphic context. The role of sea-level, tectonic and depositional controls on “stacking” and facies patterns are considered. A second major goal is to relate the occurrence of hydrocarbon pools to this sequence-stratigraphic framework.