Unit Name: Nikanassin Formation
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: Portlandian - Barremian (146 - 125 ma)
Age Justification: The Nikanassin Formation appears to range in age from Portlandian to Barremian, but fossil evidence is particularly scarce and ambiguous in the upper part of the succession.
Originator: MacKay, 1929a.
On Brown Creek, near Brulé, central Alberta Foothills in Sec. 4, Twp. 50, Rge. 27W5M. The name Nikanassin was first introduced by MacKay (1929) on G.S.C. Map 208A, Mountain Park. A type locality for the information was not designated. An incomplete section located farther to the north on Brown Creek in the Brulé Mines coal area was described by MacKay (1929). A complete section is located on Red Cap Mountain in Sec. 35, Twp. 45, Rge. 22W5M (D.F. Stott, pers. comm.).
The Nikanassin thickens northward from the foothills near North Saskatchewan River. The formation reaches about 400 m (1,312 ft) in the type area, but thins to the east due to pre-Cadomin erosion. In the plains the erosional edge curves northwestward from the Coalspur area (east of Jasper) to the vicinity of Fort St. John, and roughly parallels the Cadomin edge which lies 20 to 40 km (12 to 24 mi) to the east.
Marine and continental sandstones, and dark grey shales. The sandstones are grey, hard, mostly quartzose and are fine-grained, although the grain size increases to the north and east in the plains region. The lower beds are mainly marine and in the foothills the upper part is coastal to continental in origin, containing carbonaceous shales and small carbonaceous streaks but no commercial coal seams.
The Nikanassin sandstones grade into the underlying Jurassic Fernie shales through an interval of interbedded sandstones and shales ("Passage Beds"). The upper contact is sharp, as the Lower Cretaceous Cadomin conglomerates overlie eroded, progressively older Nikanassin beds in an easterly direction, forming a regional angular unconformity. The stratigraphic position of the Nikanassin is similar to that of the Kootenay Group in the southern foothills and to the Minnes Croup north of Smoky River. These three units represent northward regression of the sea, beginning in Late Jurassic; although generally related they are not entirely time equivalent.
Gussow, 1960; Irish, 1965; Loranger, 1958; MacKay, 1929; Mountjoy, 1962, 1962; Springer, MacDonald and Crockford, 1964; Stott, 1967, 1972; Ziegler and Pocock, 1960.
Mackay, B.R., 1929a. Mountain Park Sheet, West of Fifth Meridian, Alberta; Geological Survey of Canada, "A" Series Map 208A, Scale: 1:63 360 or 1 Inch to 1 Mile.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: R. deWit
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 02 May 2008