Sequence Stratigraphy and Resulting Reservoir and Non-reservoir Facies Distribution, Upper Devonian Winterburn Nikanassin Range Outcrops, Alberta Canada

Weissenberger, John A.; Wong, Pak K.; Gilhooly, Murray G.

Upper Devonian (Frasnian) Winterburn Group carbonates, adjacent argillaeous carbonates and shales are exposed in the Front Ranges of the Canadian Rockies along the McConnell thrust fault southwest of the town of Cadomin, Alberta. The outcrops span a transition from shallow water platform carbonates to basin-filling shale and carbonates along the flanks of the Jasper Basin, a significant Frasnian/Famennian-aged basinal embayment within the western portion of the Western Canadian Sedimentary Basin. Over six kilometres of continuous outcrop, on the vertical to sub-vertical walls of three adjoining cirques, allow an understanding of the stratigraphic relationships and facies patterns within and between 3rd order depositional sequences of the late Frasnian Winterburn Group.

Detailed section description and tracing of bedding relationships on photomontages define the overall basin-fill pattern in these sequences, with each sequence defined by geometries, stratal stacking and facies patterns.

The studied interval is represented by a succession of 3rd and constituent 4th order sequences recording systematic changes in stratal stacking pattern and resultant depositional styles. From the oldest to the youngest 4th order sequence, the following changes are noted: a) sequence 1 (upper part exposed): progradation, b) sequence 2: aggradation-progradation-downstepping, c) sequence 3: progradation-downstepping-lowstand, d) sequence 4: progradation-lowstand and e) sequence 5: aggradation-progradation-lowstand(?).

Sequences 1 to 4 depict a pattern of decreasing accommodation in the late Frasnian. This is manifested by decreasing aggradation and increasing progradation. The youngest sequences are characterized by no aggradation, limited progadation and well developed lowstand deposits and erosional truncation of foresets.

Sequence 5 depicts a turnaround to increasing accommodation as evidenced by an aggradational lower section characterized by patch reef inception.

At the Nikanassin Range, a high resolution sequence stratigraphic framework can be constructed from the excellent exposure, leading to a better understanding of accommodation change in the late Frasnian.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013