Abstract This sequence comprises the strata between the Woodbend Group (Chapter 8) and the Wabamun Group (Chapter 10). Stratigraphically it includes carbonates of the Nisku Formation and a succession of strata that comprise the "upper" Winterburn (Figure 2). This succession includes carbonates of the Blue Ridge Member of the Graminia Formation and fine siliciclastic sediments of the Calmar and Graminia "silt" intervals. Figure 1 depicts the basin configuration towards the end of Winterburn "time". It marks a major departure from the Woodbend configuration when a northeasterly opening to the basin existed between the Peace River Arch landmass and the Grosmont Platform Complex. Towards the end of Upper Nisku "time" a lobe of shale, along with coarser detrital sediment had blocked this entryway. This divided the Winterburn Basin into two geographic domains: firstly, a basin in central Alberta bordered by the "Meekwap" shelf to the north and northeast, the West Pembina shelf to the southeast and a less continuous shelf system in the Devonian "Deep Basin" to the west that presumably connected to an open seaway; and secondly, north and northwest of the Peace River Arch landmass, an early Winterburn basin that became infilled by shales of the upper part of the Fort Simpson Formation as far to the northwest as northeast British Columbia and contiguous areas of the Northwest Territories. Limestones of the Jean Marie Member of the Redknife Formation form a shelf bordering the open seaway to the west (Figure 1). The Winterburn Group consists of a lower transgressive phase and an upper regressive phase of deposition. In the lower transgressive phase shelfal carbonates of the Nisku Formation backstep away from the basin in central Alberta. During the upper regressive phase, carbonate platforms with varying amounts of evaporitic and terrigenous components, forestep into the basin.

Abstract Thick basinal sequences comprising very fine-grained sediments are common in the geological record. For the most part they present a monotonous succession of poorly defined lithologies. Although not the direct focus of exploration efforts these intervals are important in terms of permeability seals and more importantly the accumulation of hydrocarbon source sections. This article examines the nature and controls on basin filling during the Upper Devonian - Early Mississippian of the WCSB. It focuses primarily on the Ireton and Duvernay intervals of the Woodbend sequence (see Chapter 8). However, conclusions and general inferences are then related to other basin-fill successions, namely the Waterways Formation of the Beaverhill Lake Group (Chapter 7), the Winterburn shales of the Winterburn Group (Chapter 9) and finally the Exshaw - Banff shales of the early Mississippian (Chapter 11). Volumetrically basin-fill successions comprise a significant portion of the Upper Devonian to Lower Mississippian section in the WCSB. They may be grouped into three types based on gross lithology: 1) Evaporitic 2) Carbonate-rich 3) Shale-rich

Abstract This sequence comprises the strata between the Beaverhill Lake Group (Chapter 7) and the Winterburn Group (Chapter 9). The stratigraphic section includes shallow-water carbonates of the Cooking Lake, Leduc and Grosmont formations and deep-water carbonates and shales of the Majeau Lake Member, Duvernay and Ireton formations. The isolate reef complexes of the Leduc Formation are especially well known because they contain some of the largest oil reserves in the WCSB. In central Alberta, the basin-fill succession of the Woodbend Group differs markedly from that of the underlying Beaverhill Lake Group. Rather than being comprised dominantly of carbonate muds derived from coeval carbonate banks to the east, Woodbend basin-fill units have a significant clay shale content. The occurrence of these shales marks the initial delivery of terrigenous deposits into the central Alberta Basin from an extrabasinal northerly source. The configuration of these shale "banks" controls the distribution of some overlying carbonate platform deposits. Figure 1 depicts the configuration of the Alberta Basin during the Woodbend which marks the furthest incursion of the open-marine Devonian seaway onto the craton. Shallow-water platform carbonates occur along the periphery of this basin in east-central Alberta, in the Devonian "Deep Basin" area of west-central Alberta and around the Peace River Arch landmass.