Abstract Geochemical and petrologic analysis of three wells from the upper Member of the Wabamun Group in the Limestone gas field indicates a complex diagenetic history, including several episodes of dolomitization, silicification, and calcite cementation. Paleomagnetic analysis showed that several magnetization components are present in the reservoir rocks: (1) a high-temperature magnetization of probable Jurassic age (paleopole long. 81°E, lat. 78°N) carried by magnetite; (2) at least one dominant reversed-polarity characteristic remanence of Late Jurassic or Tertiary age (paleopoles long. 172°E, lat. 78°N; long. 139°E, lat. 79°N) carried by magnetite and pyrrhotite; and (3) a low-temperature and coercivity reversed-polarity magnetization (paleopole long. 235°E, lat. 77°N) that is either an uplift-induced magnetization or a late chemical remanent magnetization. The presence of several remagnetization events implies that the Laramide paleomagnetic history of the Cordillera is incompletely understood.

Abstract 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.