Unit Name: Coalspur Beds
Unit Type: Lithostratigraphic
Age Interval: Late Cretaceous - Early Tertiary (99.6 - 23.03 ma)
Originator: Mackay, 1949.
None specified. Partially exposed in the Coal Valley area in the vicinity of Coalspur, west-central Alberta, in Twp. 48, Rge. 21W5M, and in the Saunders area, in Twp. 40, Rge. 13W5M.
The name Coalspur beds to date has been used only between the North Saskatchewan and Athabasca rivers, but it may be applicable north and south of these boundaries. The name is only applied in the outer Alberta Foothills. No complete sections are known but the estimated thickness is in the order of 550 m.
Massive to thin interbedded sandstone, siltstone, mudstone and coal, with subordinate conglomerate, bentonite and tuff. The basal unit is conglomeratic and is represented by the Entrance Conglomerate in the vicinity of the Athabasca River. Thick to massive, fine- to very coarse-grained, abrupt based sandstone beds are a prominent component. Several thick coal seams occur over an interval of 100 to 200 m (328 to 656 ft) 270 m (886 ft) above the base. Interbedded olive-grey to greenish grey mudstone, siltstone and very fine-grained sandstone form thick, but often recessive units. Bentonite and tuff beds are minor but conspicuous components. One tuff bed, named the Saunders Tuff (Sanderson, 1931b) may be useful in correlation.
Overlies the Brazeau Formation abruptly. It is not certain if the contact is conformable or not. It is overlain abruptly but conformably by the Paskapoo Formation. Laterally it is equivalent to an upper part of the Wapiti Formation in the west-central Alberta Plains, approximately equivalent to the Scollard Formation of the Edmonton Group in the central plains, a lower part of the Willow Creek Formation in the southwestern Alberta plains, and part or all of the Ravenscrag Formation in southern Saskatchewan.
Used by Mackay (1949) for the interval between the Brazeau and Paskapoo formations to separate the major coal seam zone from those formations. He showed them on two of his maps, numbers 16 and 17, of the Coalspur and Saunders blocks. 'Coalspur beds' was used by Jerzykiewicz and McLean (1980) as a formation name in the Coal Valley area, but only in an informal sense because of lack of a suitable type section. However, its use has considerable merit as a lithostratigraphic unit between the Athabasca and North Saskatchewan rivers, as discussed by Jerzykiewicz and McLean (1980).
See Coalspur Formation
Jerzykiewicz, T. and McLean, J.R., 1980. Lithostratigraphic and sedimentological framework of coal-bearing Upper Cretaceous-lower Tertiary strata, Coal Valley area, central Alberta Foothills; Geological Survey of Canada, Paper 79-12.
Mackay, B.R., 1949. Coal areas of Alberta. Geological Survey of Canada, Atlas to accompany estimate of coal reserves for the Royal Commission on Coal.
Sanderson, J.O.G., 1931b. Upper Cretaceous volcanic ash beds in Alberta. Trans. Roy. Soc. Can., Ser. 3. v. 25, s. 4, p. 61-70.
Source: GEOLOGICAL SURVEY OF CANADA, CALGARY
Contributor: J.R. McLean; G.E. McCune
Entry Reviewed: No
Name Set: Lithostratigraphic Lexicon
LastChange: 29 Sep 2010