Type Locality:

Mount Dalhousie, northern spur. Located in southeastern Jasper National Park, immediately south of the junction of the Southesk and Cairn rivers; 63 km (39 mi) west-northwest of Nordegg townsite, 52°38'N, 116°58'W. Where the Cairn can be subdivided the Socony Entice No. 1 well, in 12-25-28-24W4M has been designated the type section of the upper Cairn Members between 2,183.8 and 2,304 m (7,165 and 7,560 ft) (Belyea and McLaren, 1956).

Distribution:

The Cairn Formation, including the Flume Member is between 140 and 230 m (459 and 755 ft) thick. If the Flume Member is omitted the Cairn Formation ranges from 80 to 180 m (262 to 590 ft) in thickness. Exceptionally thick sections have been reported by McLaren (1955) at Mount Coleman, and Mountjoy (1978) at Coronation Mountain. At Mount Coleman the full Cairn is 255 m (837 ft) and the upper Cairn Member 141 m (463 ft) in thickness; at Coronation Mountain they are 320 m (1,050 ft) and 156 m (512 ft) thick respectively. The Cairn Formation outcrops in the carbonate buildups of Fairholme Group of the Rocky Mountain front and main ranges, from Kakwa Lake in northeastern British Columbia to south of the Bow Valley. The lower Flume Member is also recognized in basin sections, where it has been given formation rank. The Cairn Formation does not occur in the Flathead area farther to the south (Price, 1964b), and relationships in the intervening area have not been established. The Cairn Formation is recognized in the subsurface southern Alberta carbonate shelf south of about Twp. 30 and also east of a line between Drumheller and Vermilion.

Locality Data:

WELL 100122502824W400; SOCONY ENTICE NO. 1 WELL. Thickness(m): Minimum 140, Maximum 230. Interval(m): From 2183.8, To 2304.

Lithology:

The lower cherty dolomite member (Flume Member) consists of dark grey, fine- to medium-crystalline dolomite in medium to thick beds. The dolomites may be slightly silty toward the base. The member contains Amphipora and scattered stromatoporoids, but is principally distinguished by the abundant dark grey chert nodules and stringers present in the unit. The upper organic dolomite member is composed of dark grey dolomites containing abundant Amphipora and bulbous stromatoporoid remains. Fresh rock surfaces often have a fetid odor and the unit is variably argillaceous. The thicker, more massive weathering beds contain mainly bulbous stromatoporoids with scattered Amphipora and corals, the thinner beds have abundant Amphipora and fewer stromatoporoids. There also appears to be a lateral gradation of fossil content, with stromatoporoids most abundant near the buildup margins and Amphipora dominant in the interior of buildups. The bulbous stromatoporoid beds are often lenticular in shape and probably represent low-relief biostromes. Noble (1970) divided the Cairn into five biofacies. The upper member may contain limited chert, but is distinguished from the lower (Flume) member by its thicker and more massive bedding, larger average stromatoporoid size and absence of abundant chert. Although the Cairn Formation is generally dolomitized, some limestone interbeds do occur. They are mainly peloid-intraclast wackestones and packstones, with rare grainstones. Fossils are nondiagnostic but include calcispheres, ostracods, bryozoans, corals, brachiopods, algae and foraminifera in addition to Amphipora and stromatoporoids.

Relationship:

The Cairn Formation is areally restricted to carbonate buildup and shelf facies of the Fairholme Group, although the lower Flume Member is also recognized as a formation in basin sections in the mountains. The Cairn Formation overlies the pre-Fairholme subgroup in the mountains and is overlain by the Southesk Formation. At carbonate buildup margins the Cairn may interfinger with or be or lapped by the Perdrix Formation. Subsurface relationships at the southern Alberta carbonate shelf margin between the Cairn and Duvernay formations appear to be similar. The Cairn is equivalent to the lower Leduc and Cooking Lake formations of central Alberta and to the lower Duperow Formation and possibly to the upper Souris River Formation of the Williston Basin. The Flume Member is in part equivalent to the upper Beaverhill Lake Group. The Cairn Formation in the southern Alberta carbonate shelf overlies the Beaverhill Lake Formation or Souris River Formation. The Cairn is homotaxial with the Borsato and Hollebecke of the Crowsnest area, but the exact relationships are not yet established.

History:

McLaren (1955) raised the Fairholme Formation of Beach (1943) to group status and named the former lower member the Cairn Formation. McLaren designated a new type section on Mount Dalhousie, within the Southesk-Cairn carbonate buildup. Raymond (1930) had earlier erected the Flume Formation to describe the carbonate platform underlying basin sections of Fairholme Group in the Jasper area (see Flume Formation). Correlation has since shown Raymond's Flume Formation to be equivalent to McLaren's cherty dolomite member of the Cairn Formation of carbonate buildups of the Fairholme Group. Although most geologists now recognize that the Flume Formation is a widespread carbonate platform upon which areally restricted carbonate buildups later developed (i.e., the Flume is present beneath both buildup and basin sections), the Cairn Formation has never been formally restricted to McLaren's upper organic dolomite member. Thus modern studies have called the Flume a formation in the basin, but a member of the Cairn Formation in the buildups (e.g. Cook, 1972; Mountjoy, 1965; Mountjoy and Mackenzie, 1973; Noble, 1970). Part of the reason for this situation is related to the stratigraphy of the Fairholme carbonate shelf of the southern Alberta Plains. There the lithostratigraphic equivalent of the Flume (i.e., the Cooking Lake) is not recognized where continuous organic buildup occurs, and the Cairn Formation encompasses all beds between the top of the Beaverhill Lake Group and the base of the Southesk Formation (Belyea and McLaren, 1956).

References:

Beach, H.H., 1943. Moose Mountain and Morley map-areas, Alberta; Geological Survey of Canada, Memoir 236, 74 p.

Belyea, H.R. and McLaren, D.J., 1956. Devonian sediments of the Bow Valley and adjacent areas: Alberta Society of Petroleum Geologists, Sixth Annual Field Conference Guide Book, pp. 66-91.

Cook, H.E., 1972. Miette platform evolution and relation to overlying bank ('reef') localization, upper Devonian, Alberta; in, Bulletin of Canadian Petroleum Geology, Vol. 20, Issue 3, pp. 375A.

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.

McLaren, D.J., 1955. Devonian formations in the Alberta Rocky Mountains between Bow and Athabasca rivers; Geological Survey of Canada, Bulletin 35.

Mountjoy, E.W., 1965. Stratigraphy of the Devonian Miette reef complex and associated strata, eastern Jasper National Park, Alberta; Geological Survey of Canada, Bulletin 110, 132 p.

Noble, J.P.A., 1970. Biofacies analysis, Cairn Formation of Miette reef complex (Upper Devonian), Jasper National Park, Alberta; in, Bulletin of Canadian Petroleum Geology, Vol. 18, Issue 4, pp. 493-543.

Price, R.A., 1964b. The Devonian Fairholme-Sassenach succession and evolution of reef-front geometry in the Flathead-Crowsnest Pass area, Alberta and British Columbia, in, Flathead Valley, Special Guide Book Issue, Fourteenth Annual Field Conference, Goodman, A.J. (Jack) (Ed.); The Alberta Society of Petroleum Geologists, Bulletin of Canadian Petroleum Geology, vol. 12 (August), pp. 427-451.

Raymond, P.E, 1930. The Paleozoic formations in Jasper Park, Alberta. Amer. J. Sci., 5th Ser., v. 20, p. 289-300.