ABSTRACT

Recent drilling in the northwest Saskatchewan sedimentary basin has supplied a number of key wells to clarify relationships between Alberta and Saskatchewan Elk Point units. In wells of the Meadow Lake area a series of evaporites and redbeds are found below the typical Saskatchewan Ashern formation. These have no equivalent further east in Saskatchewan and Manitoba and are called in this paper the Meadow Lake beds. They are interpreted as belonging to the lower two thirds of the Alberta Elk Point group, which is here split up into an upper unit, extending to the base of the Ashern, and a lower, Pre-Ashern unit.

The Saskatchewan Ashern is correlative with Crickmay's Member 4, or Alberta's Second Redbed. The Winnipegosis is correlative with Belyea's Stromotoporoid-coral-algal zone and the upper part of Crickmay's Member 3.

The Sub-Devonian unconformity is evident in the Meadow Lake area, where the Meadow Lake beds rest unconformably on Cambro-Ordovician sands, with Siluro-Ordovician entirely removed. To the south-east a feather edge of Pre-Ashern Elk Point evaporite is indicated in 15 feet of anhydrite resting on truncated Siluro-Ordovician in Big River No. 6 well. The Dawson Bay formation of Manitoba and Saskatchewan decreases in thickness to 30 feet and less in the Meadow Lake area. Further thinning westwards into Alberta is in evidence where the First Redbed, Dawson Bay and Second Redbed of Saskatchewan converge to Crickmay's Member No. 1, or McGehee's First Redbed of Alberta. The Dawson Bay formation is included in the Elk Point group.

The above features are expressed in a cross section.

Possible Lower Devonian age is advocated for the Pre-Ashern Elk Point of Alberta and Meadow Lake regions.

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