Unit Name: Belcourt Formation
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: Asselian - Sakmarian (299 - 284.4 ma)
Province/Territory: Alberta; British Columbia
Originator: McGugan and Rapson, 1963b.
At elevation of 2,164 m (7,100 ft) on west end of west trending ridge, northwest side of Muinok Mountain; 54 deg 20'28"N, 120 deg 24'41"W, NTS 93I/8, eastern Rocky Mountain front ranges, east-central British Columbia (McGugan and Rapson, 1963; Bamber and Macqueen, 1979).
Confined to the eastern Rocky Mountains, the Belcourt extends from northern Jasper National Park in west-central Alberta to Mountain Creek south of Pine Pass in east-central British Columbia (Bamber and Macqueen, 1979; McGugan and Rapson-McGugan, 1976). The formation varies greatly and abruptly in thickness because of block faulting and accompanying erosion prior to deposition of overlying Permian and Triassic units (McGugan and Rapson-McGugan, 1976; Bamber and Macqueen, 1979; Richards, 1989). In the Wapiti Lake region of east-central British Columbia local southwestward thinning occurs, but to the south a general southwestward thickening trend is evident. The thickest deposits lie west of Sukunka River in the northwest, where the Belcourt is over 130 m (426 ft) thick. At its faulted and poorly exposed type section the formation is between 47.8 m (157 ft) (McGugan and Rapson, 1963) and 41.6 m (137 ft) thick.
The resistant Belcourt Formation is dominantly yellowish grey, dolomitized skeletal wackestone and packestone, ooid grainstone and very fine to finely crystalline dolostone containing sand and silt (McGugan and Rapson-McGugan, 1976; Bamber and Macqueen, 1979; Henderson et al., in press). Light to medium grey skeletal and oolitic limestone (mudstone to packstone and grainstone) predominates at some northwestern outcrops in east-central British Columbia. Abundant nodules and irregular masses of grey chert are preserved in most dolostone and many limestone beds. Many carbonate beds in the eastern Belcourt contain fusulinaceans, commonly best preserved in chert nodules; other beds contain numerous colonial rugose corals. Tabular boundstone units, possibly dominated by the ?hydrozoan Palaeoaplysina lie locally in east-central British Columbia. Most sections include a basal chert and carbonate granule to boulder conglomerate or conglomeratic carbonate ranging in thickness from less than 10 cm to 5.8 m (4 in to 19 ft). Above the basal beds there are from one to several conglomerate beds that overlie intraformational erosion surfaces. Conglomerate and grainstone beds locally show medium to large scale cross-bedding. Northwestern occurrences of the formation are rhythmically bedded and show sharp based graded beds and debris flow conglomerate. Elsewhere the medium- to thick-bedded Belcourt consists of lenticular beds and massive, undulose beds.
In most areas the Belcourt unconformably overlies lower to middle Visean carbonates of the Rundle Group (Bamber and Macqueen, 1979). West of Sukunka River in east-central British Columbia it unconformably overlies uppermost Devonian shale of the Besa River Formation (Richards, 1989). The Belcourt is generally unconformably overlain by the Permian Mowitch Formation in the northeast and by the Permian Fantasque Formation to the southwest. Artinskian sandstone and siltstone (?Kindle Formation) unconformably overlie the Belcourt northwest of Sukunka River, and Triassic deposits locally overlie it to the southeast near Hook Lake. Toward the northeast the Belcourt passes into the partly coeval subsurface Belloy Formation, and is separated from the latter by an arbitrary nomenclatural boundary at the northeastern margin of the Rocky Mountains (Henderson et al., in press).
The Belcourt Formation of McGugan and Rapson (1963) is equivalent to the lower unit of Forbes and McGugan (1959) and to the Hanington Formation of Bamber and Macqueen (1979). The Hanington is known from two localities in east-central British Columbia (Bamber and Macqueen, 1979). It was differentiated from the Belcourt because the Hanington contains foraminifers that were erroneously interpreted to be of Late Carboniferous age (Ross and Bamber, 1978) and was thought to be separated from overlying Permian carbonates of the Belcourt by a regional unconformity. New, unpublished foraminiferal (pers. comm., S. Penard) and conodont data from the Hanington indicates that unit is Early Permian in age. Because Permian carbonates of the Hanington cannot be distinguished from those of the Belcourt Formation Richards (1989) and Richards et al. (in press) assigned the unit to the Belcourt. The name Hanington Formation should be abandoned.
Bamber and Macqueen, 1979; Forbes and McGugan, 1959; Henderson et al., in press; McGugan and Rapson, 1963; McGugan and Rapson-McGugan, 1976; Richards, 1989; Richards et al., in press; Ross and Bamber, 1978.
Bamber, E.W. and Macqueen, R.W., 1979. "Upper Carboniferous and Permian stratigraphy of the Monkman Pass and southern Pine Pass areas, northeastern British Columbia"; Geological Survey of Canada, Bulletin 30, 27 p.
McGugan, A, and Rapson, J.E., 1963b. Permo-Carboniferous stratigraphy between Banff and Jasper, Alberta; Bull. Can. Petrol. Geol., vol. 11, pp. 150-160.
McGugan, A. and Rapson-McGugan, J.E., 1976. Permian and Carboniferous stratigraphy, Wapiti Lake area, northeastern British Columbia. Bull. Can. Petrol. Geol., v. 25, p. 193-210.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: B.C. Richards; E.W. Bamber; C.M. Henderson
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 24 Mar 2009