Cold Lake Oil Sands Area: Formation Picks and Correlation of Associated Stratigraphy

The present preliminary assessment of regional stratigraphy of the Cold Lake oil sands area involved a comprehensive literature review, followed by detailed picking of logs, construction of a grid of cross sections, and assembling of a database of regional picks for the area. At least four major transgressive surfaces subdivide the Clearwater into the following units (in ascending order): the T31, marking the top of the Clearwater C; the T41 the top of the Clearwater B; the T51, a surface below the top of the Clearwater A; and, the T61, the top of the Clearwater A. Each of these T surfaces is a transgressive surface of erosion, and indicates a transgression of the Clearwater Sea and the base of a more regionally mappable, coarsening-upward shallow-marine succession. In the sequence-stratigraphic model the various units clinoform-downsection from Lloydminster in the south to Athabasca in the north. Each of the original shoreline successions, near the Cold Lake oil sands/ Lloydminster heavy-oil contact, is the result of a fall in relative sea level, followed by cut and backfill of associated estuarine incised valley-fills. The estuarine incised valley-fills terminate northward (seaward), discharging into lowstand delta lobe, shoreface, and submarine non-deltaic lobes in areas of low accommodation space. Further detailed work in the Cold Lake oil sands deposit will reconcile differences in correlation and definition of formation tops used by various workers in the study area.