Unit Name: Johnston Canyon Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: ? late Sakmarian - Artinskian (294.6 - 275.6 ma)
Age Justification: Typified by occurrence of Zoophycos and spicular chert nodules. Fusulinaceans in silicified limestone lens at Crossing Creek (Sec. 26, McGugan et al., 1964). Conodonts from various sections from southeastern British Columbia to the type section in the Banff area have been recovered, indicating a late Sakmarian? to Artinskian age.
Province/Territory: Alberta; British Columbia

Originator: McGugan, A. and Rapson. J.E., 1963b, p. 56.

Type Locality:
West Flank of Mount Ishbel, Sawback Range, Banff National Park. Sec. 4, McGugan and Rapson, 1961b (51 deg 16'N, 115 deg 47'W).

Distribution:
57 m (187 ft) at the type section; maintains this thickness over most of the area from Crowsnest Pass to the Banff area. Apparently merges into thin, easternmost front range conglomeratic condensates in the southern Rockies. Absent in the foothills subsurface, except for the homotaxial Belloy Formation of the Peace River subsurface. Not recognized north of Mount Malloch, Clearwater River Section 86 (McGugan et al., 1964), although may be age equivalent to the lower part of the Mount Greene beds near Peace River (McGugan, 1967), and part of unit C, Chowade Group (Hovdebo, 1962).

Lithology:
Dark grey, rhythmic sequence of shaly, phosphate siltstones, calcareous siltstones and silty carbonates, with quartz vugs on bedding planes. Abundant black, spicular chert nodules and burrow fillings. Silicified limestone lens with fusulinaceans and other biota at Crossing Creek (Section 26, McGugan et al., 1964).

Relationship:
Paraconformably overlies Middle Pennsylvanian Kananaskis Formation where that formation is present. Overlies Lower Pennsylvanian Tunnel Mountain Formation in the westerly front ranges. Unconformably overlain by Ranger Canyon Formation with basal conglomerate everywhere except on Telford Creek Ridge, southeastern British Columbia (McGugan, 1963; McGugan and Rapson, 1963b), where it is overlain in conformable transition by the Telford Formation. Homotaxial in part with the Belcourt Formation, Mount Greene beds and Kindle Formation of the northern Rocky Mountains and foothills, as well as part of the Belloy Formation of the Peace River embayment. A unit lithologically similar, but older (Asselian) than the type Johnston Canyon, it underlies the Telford Formation at the Telford thrust plate section where it is referred to as the Johnston Canyon Formation ("Johnston Canyon Formation" in Henderson, 1989).

History:
McGugan and Rapson (1961b) proposed the name Ishbel Formation for the upper part of the Norquay formation in the Band area and divided the formation into upper Ishbel and lower Ishbel. The lower Ishbel was subsequently named Johnston Canyon Formation when the Ishbel was raised to group status.

Other Citations:
Henderson, 1939; Henderson et al, in press; Henderson and McGugan, 1986; Hovdebo, 1962; MacRae and McGugan, 1977; McGugan, 1974; McGugan et al., 1964; McGugan and Rapson, 1961b, 1963a, 1963b.

References:
McGugan, A, and Rapson, J.E., 1963b. Permo-Carboniferous stratigraphy between Banff and Jasper, Alberta; Bull. Can. Petrol. Geol., vol. 11, pp. 150-160.

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: C.M. Henderson; A. McGugan
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 23 Dec 2008