Manitoba Group
The Manitoba Group is a stratigraphical unit of middle to late Devonian age in the Western Canadian Sedimentary Basin.
| Manitoba Group | |
|---|---|
| Stratigraphic range: | |
| Type | Geological group |
| Sub-units | Souris River Formation Hubbard Evaporite Dawson Bay Formation |
| Underlies | Duperow Formation 9Saskatchewan Group |
| Overlies | Prairie Evaporite Formation, Winnipegosis Formation (Elk Point Group) |
| Thickness | up to 244 metres (800 ft)[1] |
| Lithology | |
| Primary | Shale, carbonate, evaporite |
| Location | |
| Region | WCSB |
| Country | .svg.png.webp){kind=small} Canada |
| Type section | |
| Named for | Manitoba |
| Named by | A.D. Baillie, 1953 |
The group takes its name from the province of Manitoba, and was first defined by A.D. Baillie in 1953.[2]
Lithology
The Manitoba Group is composed of alternating cycles of shale, carbonate and evaporite. [1]
Distribution
The Manitoba Group occurs in outcrop in southwestern Manitoba and in the sub-surface in southern Saskatchewan, North Dakota and Montana.[1] It reaches a maximum thickness of 150 metres (490 ft) in outcrop and up to 244 metres (800 ft) in the sub-surface.
Subdivisions
The following formationas are recognised, from top to bottom:
- The Souris River Formation appears in the upper part of the Manitoba Group, is of Givetian to Frasnian age and consists of thin shale-carbonate-evaporite cycles.[3]
- The Hubbard Evaporite is recognised at the top of the Montana Group in the Elk Point Basin. Its age is Givetian[4]
- The Dawson Bay Formation is the lower part of the Manitoba Group. It is of Givetian age and consists of red shale (the "Second Red Bed") and a sequence of limestone and dolomitic limestone.[5]
Relationship to other units
The Manitoba Group is conformably overlain by the Duperow Formation and disconformably overlays the Prairie Evaporite Formation or Winnipegosis Formation of the Elk Point Group.[1]
The lower Manitoba Group is equivalent to the Muskeg Formation in northern Alberta, while the upper part correlates with the Beaverhill Lake Formation.
References
- Lexicon of Canadian Geologic Units. "Manitoba Group". Retrieved 2010-01-10.
- Baillie, A.D., 1953. Devonian System of the Williston Basin area. Manitoba Mines Branch, Pub. 52-5.
- Lexicon of Canadian Geologic Units. "Souris River Formation". Retrieved 2010-01-10.
- Lexicon of Canadian Geologic Units. "Hubbard Evaporite". Retrieved 2010-01-10.
- Lexicon of Canadian Geologic Units. "Dawson Bay Formation". Retrieved 2010-01-10.