Alexo Formation

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Alexo Formation
Stratigraphic range: late Frasnian to early Famennian
Type Formation
Underlies Palliser Formation
Overlies Southesk Formation, Mount Hawk Formation
ThicknessUp to about 100 metres (330 ft) [1]
Lithology
Primary Dolomite
Other Siltstone
Location
Coordinates 52°26′00″N115°54′00″W / 52.43333°N 115.90000°W / 52.43333; -115.90000 (Alexo Formation)
RegionFlag of Alberta.svg  Alberta
CountryFlag of Canada (Pantone).svg  Canada
Type section
Named for Alexo, Alberta
Named byR. de Wit and D.J. McLaren, 1950. [2]

The Alexo Formation a stratigraphic unit of Late Devonian (late Frasnian to early Famennian) 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 [2] and conodonts. [3] [4]

Contents

Lithology and thickness

The Alexo Formation was deposited in a marine setting and consists of dolomite, silty and argillaceous dolomite, dolomitic siltstone, and vuggy dolomite. It has a maximum thickness of about 100 metres (330 ft), and is thinner in areas where it covers carbonate buildups (reefs) in the underlying formations. [1]

Distribution and relationship to other units

The Alexo Formation is present in the central Rocky Mountains of Alberta and the adjacent foothills, extending from the Crows Nest Pass area in the south to the North Saskatchewan River in the north. It overlies the Southesk or Mount Hawk Formation, depending on the location. It is overlain by the Palliser Formation. [1] [5]

The Alexo was originally considered to extend as far north as Jasper but was revised by McLaren and Mountjoy in 1962. In the area between the North Saskatchewan River and Jasper, they designated the upper beds of the Alexo as the Sassenach Formation, and the lower beds as part of the upper Southesk Formation. [6]

See also

Related Research Articles

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.

<span class="mw-page-title-main">Palliser Formation</span>

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 Winterburn Group is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.

The Crowfoot Formation is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.

<span class="mw-page-title-main">Tunnel Mountain Formation</span> Geologic formation in Alberta, Canada

The Tunnel Mountain Formation is a geologic formation that is present on the western edge of the Western Canada Sedimentary Basin in the Canadian Rockies of western Alberta. Named after Tunnel Mountain near Banff, it was deposited during the Early Pennsylvanian sub-period of the Carboniferous period.

<span class="mw-page-title-main">Cairn Formation</span>

The Cairn Formation is a geologic formation of Late Devonian (Frasnian) age in the Western Canada Sedimentary Basin. It was named for the Cairn River near its junction with the Southesk River in Jasper National Park by D.J. McLaren in 1955.

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 Beaverfoot Formation is a stratigraphic unit of Late Ordovician to Early Silurian (Llandovery) age. It is present on the western edge of the Western Canada Sedimentary Basin in the Rocky Mountains of British Columbia and Alberta, and the Purcell Mountains of British Columbia. It consists of carbonate rocks, and was named for the Beaverfoot Range at Pedley Pass southeast of Golden, British Columbia by L.D. Burling in 1922.

The Skoki Formation is a stratigraphic unit of Early to Middle Ordovician age that is present on the western edge of the Western Canada Sedimentary Basin in the Canadian Rockies of Alberta and British Columbia. It was named for Skoki Mountain near Lake Louise in Banff National Park by Charles Doolittle Walcott in 1928. The Skoki Formation is fossiliferous and includes remains of brachiopods and other marine invertebrates, as well as conodonts and oncolites.

The Sulphur Mountain Formation is a geologic formation of Early to Middle Triassic age. It is present on the western edge of the Western Canada Sedimentary Basin in the foothills and Rocky Mountains of western Alberta and northeastern British Columbia. It includes marine fossils from the time shortly after the Permian-Triassic extinction event.

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.

Toad Formation, Grayling Formation, and Toad-Grayling Formation are obsolete names for the strata of the Early to Middle Triassic Doig and Montney Formations. They were applied in the foothills and Rocky Mountains of northeastern British Columbia, on the western edge of the Western Canada Sedimentary Basin. Although the names are considered obsolete, their usage persists.

<span class="mw-page-title-main">Spray River Group</span>

The Spray River Group is a stratigraphic unit of Triassic age. It is present on the western edge of the Western Canada Sedimentary Basin in the foothills and Rocky Mountains of western Alberta. It was originally described as the Spray River Formation by E.M. Kindle in 1924 and was later raised to group status. Its type section is located in the Spray River gorge at the southern end of Sulphur Mountain.

The Sassenach 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 mudstone, siltstone, and silty carbonate rocks, and was named for Mount Sassenach in Jasper National Park by D. J. McLaren and E. W. Mountjoy in 1962.

The Maligne 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 Rocky Mountains and foothills of Alberta and British Columbia. It consists primarily of argillaceous limestone and calcareous mudstone, and was named for the Maligne River in Jasper National Park by P.W. Taylor in 1957.

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.

References

  1. 1 2 3 Glass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. ISBN   0-920230-23-7.
  2. 1 2 de Wit, R. and McLaren, D.J. 1950. Devonian sections in the Rocky Mountains between Crows Nest Pass and Jasper, Alberta. Geological Survey of Canada, Paper 50-23, 66 p.
  3. ↑ Clark, D.L. and Ethington, R.L. 1965. Conodont biostratigraphy of part of the Devonian of the Alberta Rocky Mountains. Bulletin of Canadian Petroleum Geology, vol. 13, no. 3, p. 382-388.
  4. ↑ McLean, R.A. and Klapper, G. 1998. Biostratigraphy of Frasnian (Upper Devonian) strata in western Canada, based on conodonts and rugose corals. Bulletin of Canadian Petroleum Geology, vol. 46, no. 4, p. 515-563.
  5. ↑ Alberta Geological Survey. "Alberta Table of Formations, May 2019" (PDF). Alberta Energy Regulator. Retrieved 24 March 2020.
  6. ↑ McLaren, D.J. and Mountjoy, E.W. 1962. Alexo equivalents in the Jasper region. Geological Survey of Canada, Paper 62-23.
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