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: Middle Devonian to Late Devonian PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
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	Canada
Type section
Named for	Manitoba
Named by	A.D. Baillie, 1953

It takes the 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

1. Lexicon of Canadian Geologic Units. "Manitoba Group". Retrieved 2010-01-10.
2. Baillie, A.D., 1953. Devonian System of the Williston Basin area. Manitoba Mines Branch, Pub. 52-5.
3. Lexicon of Canadian Geologic Units. "Souris River Formation". Retrieved 2010-01-10.
4. Lexicon of Canadian Geologic Units. "Hubbard Evaporite". Retrieved 2010-01-10.
5. Lexicon of Canadian Geologic Units. "Dawson Bay Formation". Retrieved 2010-01-10.