Unit Name: Perdrix Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Frasnian (385.3 - 374.5 ma)
Province/Territory: Alberta; British Columbia

Originator: Raymond, 1930

Type Locality:
Roche Miette, northeast shoulder, 34 km (21 mi) north-northeast or Jasper, Alberta, along Highway 16. (53 deg 10'N, 117 deg 55'W).

The Perdrix Formation is present in basinal sections of the Fairholme Group in the front and main ranges of the Rocky Mountains from the Kakwa Lake area of northeast British Columbia to the Ram River area of Alberta, a distance of 370 km (229 mi). The formation is also recognized in the subsurface immediately adjacent to the mountain front (Belyea, 1958). The Perdrix Formation is thickest adjacent to the buildups of the Fairholme Group, where it contains a higher proportion of carbonate than truly basinal sections. Within the basin sections it also appears to thicken southward. Mountjoy and Mackenzie (1973) record around 80 m (262 ft) at the Ancient Wall. Thicknesses of 110 m (361 ft) are common in basin sections in the Colin Range, while 140 m (460 ft) is more typical in the Brazeau and Cline River areas (McLaren, 1955).

The Perdrix Formation is composed of dark grey to black calcareous shale that weathers dark and recessive in outcrop. The upper half to one third of the Perdrix contains nodules or thin nodular beds of dark argillaceous limestone which increase in frequency upwards and laterally toward carbonate buildups of the Fairholme Group. The shales are generally bituminous, with fresh surfaces having a fetid odor. Hopkins (1972) found Perdrix shales in the area of the Ancient Wall and Miette buildups to contain 1 to 6% organic matter, and clays to be illitic in composition. The thin limestone interbeds and nodules consist of argillaceous, micro-sparry lime mudstone, with increasing amounts of skeletal wackestone and packstone near buildups. Brachiopods and pelecypods are present in more carbonate-rich sections, but the only ubiquitous fossils are tentaculitids.

The Perdrix Formation overlies the Maligne Formation, or the Flume Formation where the Maligne is absent, with apparent conformity, although paleontologic studies by Maurin and Raasch (1972) suggest that this boundary marks a hiatus. The Mount Hawk Formation overlies the Perdrix Formation conformably. The change is transitional, with the boundary being placed where limestone interbeds become prominent upwards. This transition corresponds to a weathering change, the Perdrix Formation being darker and recessive. Hopkins (1972) reinforced the validity of a formation break at this point with the finding that the Perdrix shales are composed of illite, whereas Mount Hawk shales contain both illite and appreciable amounts of chlorite. In basin sections the formation boundary appears sharp and is denoted by a marked weathering color change on talus covered ridges. Laterally the Perdrix Formation intertongues with most of the Peechee Member and also the upper Cairn Formation of the buildups of the Fairholme Group. The Perdrix Formation is lithostratigraphically the approximate equivalent of the subsurface Duvernay Formation and Majeau Lake Member of the Cooking Lake Formation.

The formation is named from Roche à Perdrix, 10 km (6 mi) northeast of Roche Miette. The type section of Raymond (1930) was revised by McLaren (1955), who removed the upper 47.5 m (156 ft) and added it to the Mount Hawk Formation, making the thickness of the Perdrix Formation at Roche Miette 116 m (380 ft).

Belyea, H.R., 1958. Designation of type section Camrose Tongue, Upper Devonian, Alberta; J. Alberta Soc. Petrol. Geol., vol. 6, pp. 105-110.
Mackenzie, W.S. and Mountjoy, E.W., 1973. Stratigraphy of the southern part of the Devonian ancient wall carbonate complex, Jasper National Park, Alberta; Geological Survey of Canada, Paper 72-20, 121 p.
Maurin, A.F. and Raasch, G.O., 1972. Notes et Memoires - Compagnie Francaise des Petroles Early-Frasnian stratigraphy, Kakwa-Cecilia Lakes, British Columbia, Canada; Notes et Memoires - Compagnie Francaise des Petroles, 1972, Vol. 10, 80 p.
McLaren, D.J., 1955. Devonian formations in the Alberta Rocky Mountains between Bow and Athabasca rivers; Geological Survey of Canada, Bulletin 35.
Raymond, P.E, 1930. The Paleozoic formations in Jasper Park, Alberta. Amer. J. Sci., 5th Ser., v. 20, p. 289-300.

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: E.W. Mountjoy; M.P Coppold
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 28 Mar 2014