Cairn Formation | |
---|---|
Stratigraphic range: Frasnian ~ | |
Type | Formation |
Unit of | Fairholme Group |
Underlies | Southesk Formation |
Overlies | Flume Formation |
Thickness | Up to 180 m (590 ft) |
Lithology | |
Primary | Dolomite |
Other | Limestone, chert |
Location | |
Coordinates | 52°38′N116°58′W / 52.633°N 116.967°W |
Approximate paleocoordinates | 13°30′S44°24′W / 13.5°S 44.4°W |
Region | Alberta |
Country | Canada |
Type section | |
Named for | Cairn River, Alberta |
Named by | D.J. McLaren |
Year defined | 1955 [1] |
The Cairn Formation is a geologic formation of Late Devonian (Frasnian) age in the Western Canada Sedimentary Basin. [2] It was named for the Cairn River near its junction with the Southesk River in Jasper National Park by D.J. McLaren in 1955. [1]
The Cairn Formation is stratigraphically equivalent to the Leduc Formation, which is a major oil-producing formation in central Alberta. Like the Leduc Formation, it was deposited in reef environments and is highly fossiliferous. [3] [4] Extensive outcrops of the Cairn Formation near Canmore, Alberta are a popular field trip destination for those wishing to learn about Devonian reefs. They are also popular with rock climbers who enjoy the challenges presented by their extremely irregular surfaces.
The Cairn Formation was originally deposited as limestones and mudstones in intertidal to subtidal reef environments, and was extensively dolomitized during later diagenesis. It now consists primarily of buff to dark grey, very fine to medium grained crystalline dolomite with good intercrystalline, biomoldic and vuggy porosity. Most of it is classified as floatstone, with stromatoporoids and other fossils supported in a dolomite matrix. [4] [5] The Cairn also includes minor amounts of undolomitized limestone and chert. [6]
Bulbous stromatoporoids are particularly common in the Cairn Formation and were the main reef-building organism. [7] There are also tabular stromatoporoids, Amphipora, horn corals, tabulate corals such as Thamnopora, brachiopods, crinoids, algae and foraminifera. [5] [8] The organisms are commonly either in growth position or have only been moved short distances. Some stromatoporoids show evidence of bioerosion by boring sponges. [4]
The Cairn Formation typically ranges from 80 m (260 ft) to 180 m (590 ft) in thickness. It occurs in outcrop in the front and main ranges of the Canadian Rockies from Kakwa Lake in northeastern British Columbia to south of the Bow River in Alberta. It is also recognized in the subsurface in some areas. [6]
The Cairn Formation rests conformably on the Flume Formation, which is considered to be the lower member of the Cairn Formation in some areas, and it is overlain by the Peechee Member of the Southesk Formation. [9] At reef margins the Cairn may interfinger with the Perdrix Formation which was deposited in deeper water, off-reef environments. [6]
The Cairn Formation is equivalent to, but not contiguous with, the lower Leduc Formation which lies farther to the east in central Alberta. It is also equivalent to the Cooking Lake Formation in central Alberta, and to the lower Duperow Formation and possibly the upper Souris River Formation in the Williston Basin. Its relationship to units in the Crowsnest Pass area of southern Alberta has not been established. [6]
The Leduc Formation is a stratigraphic unit of Late Devonian (Frasnian) age in the Western Canada Sedimentary Basin. It takes its name from the city of Leduc, and it was formally described from the B.A. Pyrz No. 1 well in central Alberta, between the depths of 1,623.7 m (5,327 ft) and 1,807.5 m (5,930 ft), by Imperial Oil Limited in 1950. Supplementary information came from a complete section of the formation that was cored in Imperial Oil's Leduc No. 530 well between 1,633 m (5,358 ft) and 1,863 m (6,112 ft).
The Exshaw Formation is a stratigraphic unit in the Western Canada Sedimentary Basin. It takes the name from the hamlet of Exshaw, Alberta in the Canadian Rockies, and was first described from outcrops on the banks of Jura Creek north of Exshaw by P.S. Warren in 1937. The formation is of Late Devonian to Early Mississippian age as determined by conodont biostratigraphy, and it straddles the Devonian-Carboniferous boundary.
The Horn River Formation is a stratigraphic unit of Devonian age in the Western Canadian Sedimentary Basin.
The Palliser Formation is a stratigraphic unit of Late Devonian (Famennian) age in the Western Canada Sedimentary Basin. It is a thick sequence of limestone and dolomitic limestone that is present in the Canadian Rockies and foothills of western Alberta. Tall cliffs formed of the Palliser Formation can be seen throughout Banff and Jasper National Parks.
The Beaverhill Lake Group is a geologic unit of Middle Devonian to Late Devonian age in the Western Canada Sedimentary Basin that is present in the southwestern Northwest Territories, northeastern British Columbia and Alberta. It was named by the geological staff of Imperial Oil in 1950 for Beaverhill Lake, Alberta, based on the core from a well that they had drilled southeast of the lake, near Ryley, Alberta.
The Elk Point Group is a stratigraphic unit of Early to Middle Devonian age in the Western Canada and Williston sedimentary basins. It underlies a large area that extends from the southern boundary of the Northwest Territories in Canada to North Dakota in the United States. It has been subdivided into numerous formations, number of which host major petroleum and natural gas reservoirs.
The Woodbend Group is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.
The Winterburn Group is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.
The Slave Point Formation is a stratigraphical unit of Middle Devonian age in the Western Canadian Sedimentary Basin.
The Upper and Lower Grassi Lakes lie at an elevation of about 1,525 m (5,003 ft) in the southern Canadian Rockies overlooking the town of Canmore, Alberta. They receive their water from the Spray Lakes Reservoir on the Spray River. The land is part of the Canmore Nordic Centre Provincial Park, which is part of the Kananaskis Country park system.
The Alexo Formation a stratigraphic unit of Late Devonian age. It is present on the western edge of the Western Canada Sedimentary Basin in the central Rocky Mountains and foothills of Alberta. The formation consists primarily of dolomite. It is locally fossiliferous and includes remains of marine animals such as brachiopods and conodonts.
The Mount Hawk Formation is a stratigraphic unit of Late Devonian age. It is present on the western edge of the Western Canada Sedimentary Basin in the Rocky Mountains and foothills of Alberta. It consists primarily of limestone and mudstone, and was named for Hawk Mountain in Jasper National Park by R. de Wit and D.J. McLaren in 1950.
The Flume Formation is a geologic formation in the Western Canada Sedimentary Basin in Alberta, Canada. It was deposited as an extensive carbonate platform along the western edge of the basin during Late Devonian (Frasnian) time and the reefs of the Cairn Formation subsequently developed on it.
The Perdrix Formation is a geologic formation of Late Devonian (Frasnian) age in the Western Canada Sedimentary Basin. It named for Roche à Perdrix in Jasper National Park, Alberta, by P.E. Raymond in 1930. It includes fossils of marine animals.
The Simla Formation is a stratigraphic unit of Late Devonian age. It is present on the western edge of the Western Canada Sedimentary Basin in the Rocky Mountains and foothills of west-central Alberta and east-central British Columbia. It consists primarily of carbonate rocks and siltstone, and was named for Mount Simla in northern Jasper National Park by D. J. McLaren and E. W. Mountjoy in 1962.
The Southesk Formation is a stratigraphic unit of Late Devonian age. It is present on the western edge of the Western Canada Sedimentary Basin in the Rocky Mountains and foothills of Alberta and southeastern British Columbia. It was named for the Southesk River in Jasper National Park by D.J. McLaren in 1955.
The Yahatinda Formation is a geologic formation of Middle Devonian (Givetian) age in the southwestern part of the Western Canada Sedimentary Basin in the mountains of southwestern Alberta. Its type locality lies the on the eastern face of Wapiti Mountain above Ya-Ha-Tinda Ranch at the eastern edge of Banff National Park. The Yahatinda contains a variety of Devonian fossils.
The Fairholme Group is a stratigraphic unit of Late Devonian (Frasnian) age. It is present on the western edge of the Western Canada Sedimentary Basin in the Rocky Mountains and foothills of Alberta and British Columbia. It was named for the Fairholme Range near Exshaw in the Canadian Rockies by H.H. Beach in 1943.
The La Loche Formation is a geologic formation of early Middle Devonian (Eifelian) age in the Western Canada Sedimentary Basin. It is present in northeastern Alberta and northwestern Saskatchewan and was first described by A. W. Norris in 1963, who named it for a Roman Catholic Mission at Lac La Loche. Its type section is located at Contact Rapids on the Clearwater River in Saskatchewan, northwest of Lac La Loche. It is not fossiliferous.
The Borsato Formation is a stratigraphic unit of Late Devonian (Frasnian) age. It is present on the western edge of the Western Canada Sedimentary Basin in the southern Rocky Mountains of Alberta and British Columbia. It consists of dolomite and was named for Mount Borsato in the Flathead Range near North Kootenay Pass by R.A. Price in 1965.
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