THE VIKING (ALBIAN) RESERVOIR SANDSTONES OF CENTRAL AND SOUTH-CENTRAL ALBERTA, CANADA .2. LITHOFACIES ANALYSIS, DEPOSITIONAL-ENVIRONMENTS AND PALEOGRAPHIC SETTING

During Upper Albian times, the Haplophragmoides gigas and Inoceramus comancheanus sea occupied the interior of the North American continent. Deltas draining the Cordilleran mountains around Jasper and Long. 49d̀ funnelled clastics into the Albertan sector of this sea, particularly during Viking time (early Late Albian). These Viking reservoir sands were distributed along the strandline and offshore environments during a relatively still‐stand phase of the sea. Along the western shoreline, wave, longshore and tidal currents shaped these sands into NW—SE trending barrier islands, comprising 11 sub‐facies (ebb‐tidal delta, marginal spillover channel, middle shoreface, marine shale, upper shore‐beach, dune, back‐barrier mudflat, lagoon‐washover, mixed tidal flat, tidal‐creek channel and overbank), about 32‐m thick and over 116‐kms long. These sandstone islands migrated imbricatedly in a NE direction. In the offshore setting, about 20–250 kms from shore, tidal currents fashioned the sands into NW ‐ SE trending, parallel, linear, large‐scale sandridges, two to 30‐m thick, and about 25‐to 75‐kms long on average. The tidal sandridge sub‐facies, from base to top, include: lower bioturbated, heterolithic, cross‐stratified, upper bioturbated and chert pebble conglomerate units. Deposition of some of the ridges occurred below effective wave‐base. Storm‐and gravity‐induced currents complemented tidal currents in places. Copyright © 1990, Wiley Blackwell. All rights reserved