Abstract

The Lower Cretaceous Viking Formation in south-central Alberta is an asymmetrical transgressive-progradational cyclic succession within which two major progradational sequences are recognizable. Cores of the Viking Formation depict a range of facies sequences depending upon geographic position within the depositional basin, and upon stratigraphic position within the overall cyclic succession. This variability in facies association is amply illustrated by comparison of cores from the Joffre and Caroline oil fields. Individual core sequences from Joffre exhibit evidence for both wave-dominated and current-influenced shallow shelf settings. The composite sequence is interpreted to reflect shoreface progradation in a wave-dominant setting, followed by transgression and subsequent deposition of coarse-grained detritus by inner shelf currents, seaward of the shoreface toe. The cored sequence at Caroline is part of a younger progradational sequence, and is characterized by a shoreline-attached, prograding shoreface sand wedge, within which the influence of storm-wave deposition was prevalent. The Caroline sandstone is also truncated by conglomeratic sandstone deposits, which are thought to record the onset of another major transgressive event.