F.A. Stoakes, 1992. "Early Mississippian Megasequences", 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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Early Mississippian sediments of the Western Canada Sedimentary Basin comprise a thick sequence of basinal shales, shallow-water carbonates and isolate Waulsortian reefs. The sediments described in this section are assigned to the uppermost Wabamun Group and the Exshaw Formation of largely Famennian age and the Banff, Pekisko and Shunda formations of Tournaisian age (Figure 1). This section comprises at least two transgressive-regressive cycles of sedimentation. The lowermost cycle, termed the Banff cycle by Stoakes, (1987a), actually commences in the uppermost Wabamun (Figure 2). It terminates with progradation of ramp deposits of the lower part of the Pekisko Formation. The second cycle commences with backstepping of the Pekisko ramps and initiation, in downslope positions, of isolate Waulsortian reefs. The cycle terminates with progradation and basin-filling of the Shunda Formation. Although the overall picture is still not that clear it would appear that each Mississippian cycle represents increased reflooding of the WCSB and as such is part of a much large depositional phase. The area where these patterns are perhaps best known is in the area of the Peace River Arch where an anomalously thick sedimentary succession of Carboniferous age is preserved (O'Connell, 1990).
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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.