Gravelbourg Formation

Gravelbourg Formation
Gravelbourg Formation
Stratigraphic range: Bajocian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Gravelbourg, Saskatchewan
Named by	R.L. Milner and G.E. Thomas, 1954

The Gravelbourg Formation is a stratigraphical unit of Bajocian age in the Western Canadian Sedimentary Basin.

It takes the name from the town of

Gravelbourg, and was first described in well Tidewater Eastend Crown No. 1 by R.L. Milner and G.E. Thomas in 1954.^[2]

Lithology

The Gravelbourg Formation is divided in two members, Lower and Upper Gravelbourg. The lower member is composed of

chalcedonic chert and anhydrite in the lower part and a basal shale bed with fish scales and anhydrite. The upper Gravelbourg consists of dark shale with sandstone and argillaceous limestone stringers and a tan mudstone

bed at the top. [1]

Distribution

The Gravelbourg Formation reaches a maximum thickness of 60 metres (200 ft) in the Williston Basin. At its type locality in southwestern Saskatchewan, it is 27 metres (90 ft) thick.^[1] It thins out westwards at the eastern flank of the Sweetgrass Arch in southern Alberta and eastwards into southwestern Manitoba.

Relationship to other units

The Gravelbourg Formation is conformably overlain by the Shaunavon Formation. It conformably overlies the Watrous Formation in Manitoba and southeastern Saskatchewan, and unconformably overlays the Madison Group in south-eastern Alberta.^[1]

The Lower Gravelbourg is equivalent to the

Piper Formation

in North Dakota and Montana.

References

^ ^a ^b ^c ^d Lexicon of Canadian Geologic Units. "Gravelbourg Formation". Retrieved 2010-01-31.
^ Milner, R.L. and Thomas, G E., 1954. Jurassic System in Saskatchewan. In: Western Canada Sedimentary Basin, American Association of Petroleum Geologists, p. 250-267

[lexicon-1] Lexicon of Canadian Geologic Units. "Gravelbourg Formation". Retrieved 2010-01-31.

[2] Milner, R.L. and Thomas, G E., 1954. Jurassic System in Saskatchewan. In: Western Canada Sedimentary Basin, American Association of Petroleum Geologists, p. 250-267

[2]

[1]

v t e Western Canadian Sedimentary Basin
Hydrocarbon history	Oil sands and heavy oil Frontier exploration and development Natural gas liquids Natural gas
Depositional regions	Southern Alberta Central Alberta Northwestern Alberta Plains South-central Canadian Rockies foothills North-east Plains North-central foothills Liard River Fort Nelson Northern Rocky Mountains Fort St. John Saskatchewan Western Manitoba
Saskatchewan	Cypress Hills FM Ravenscrag FM Frenchman FM Whitemud FM Eastend FM Bearpaw FM Judith River GRP Belly River FM Oldman FM Foremost FM Lea Park FM Pakowki FM Milk River FM Colorado GRP Viking FM Mannville GRP Pense FM Cantuar FM Success FM Vanguard FM Ellis GRP Swift FM Rierdon FM Sawtooth FM Shaunavon FM Piper FM Gravelbourg FM Gypsum Springs FM Watrous FM Big Snowy GRP Madison GRP Charles FM Poplar Ratcliffe Midale Mission Canyon FM Kisbey SS Alida Tilston Lodgepole FM Souris Valley Three Forks GRP Bakken FM Big Valley FM Torquay FM Saskatchewan GRP Birdbear FM Duperow FM Manitoba GRP Souris River FM Elk Point GRP Davson Bay FM Prairie FM Winnipegosis FM Ashern FM Interlake FM Stonewall FM Stony Mountain FM Herald FM Yeoman FM Winnipeg FM Deadwood FM Canadian Shield