Rundle Group

Rundle Group
Stratigraphic range: Middle to Late Mississippian
The massive limestone beds form outcrops at the top of Mount Rundle
TypeGeological formation
Sub-unitsDebolt, Shunda, Pekisko, Mount Head, Livingstone, Turner Valley, Prophet
UnderliesFernie Formation, Belloy Formation
OverliesBanff Formation
Thicknessup to 741 metres (2,430 ft)[1]
Lithology
PrimaryLimestone
OtherChert
Location
Coordinates51°07′49″N 115°28′40″W / 51.13020°N 115.47765°W / 51.13020; -115.47765 (Rundle Group)
Region Alberta,  British Columbia
Country Canada
Type section
Named forMount Rundle
Named byR.J.W. Douglas, 1953

The Rundle Group is a stratigraphical unit of Mississippian age in the Western Canadian Sedimentary Basin.

It takes the name from Mount Rundle (itself taking the name from Robert Terrill Rundle), and was first described in outcrops at the northern side of the mountain in Banff National Park by R.J.W. Douglas in 1953.[2]

Lithology

The Rundle Group consists of massive limestone interbedded with dark argillaceous limestone. Chert nodules are observed in the shaley beds, and crinoids and brachiopods are observed in the clean massive beds.[1] Dolimitization is observed in the Elkton Member of the Turner Valley Formation.

Distribution

The Rundle Group reaches a maximum thickness of 741 feet (230 m) at Tunnel Mountain. It thins out toward east and north and is completely eroded or absent in east central and only the lower part occurs in southern Alberta.[1]

Relationship to other units

The Rundle Group is disconformably overlain by the Rocky Mountain Formation in the front ranges of the Canadian Rockies and by the Fernie Formation in the foothills and by Cretaceous beds in the prairies. It conformably overlies the Banff Formation.[1]

The Rundle Group can be correlated with the Mission Canyon Formation in southern Saskatchewan, northeastern Montana and North Dakota.

Subdivisions

The Rundle Group comprises the Mount Head Formation and Livingstone Formation in the Rocky Mountains; by the Turner Valley Formation, Shunda Formation and Pekisko Formation in the foothills and plains. It is equivalent to the Debolt Formation and Prophet Formation in north-eastern British Columbia and west-northern Alberta.[1] Debolt, Shunda and Pekisko Formations are staked in the Fort Nelson area.

Canadian Rockies

Sub-unit Age Lithology Max.
Thickness		 Reference
Mount Head Formation Visean Wileman Member - silty dolomite
Baril Member - ooid grainstone, dolomite
Salter Member - dolomite, boundstone and wackestone, ooid grainstone, anhydritechert
Loomis Member - massive grainstone
Marston Member - microcrystalline dolomite, boundstone, breccia, ooid limestone, shale, marlstone
Opal Member - grainstone, subordinate marlstone, chert packstone and wackestone, shale, marlstone, breccia
Carnarvon Member - wackestone to packstone, shale interbeds		 7.6 m (20 ft)
39 m (130 ft)
67 m (220 ft)
101 m (330 ft)
68 m (220 ft)
161 m (530 ft)
90 m (300 ft) 		[3]
Livingstone Formation Tournaisian to Visean crinoidal limestone, massive limestone, thin argillaceous limestone beds, dolomite 452 m (1,480 ft) [4]

Foothills and plains

Sub-unit Age Lithology Max.
Thickness		 Reference
Turner Valley Formation Visean crinoidal limestone and crystalline dolomite; two porous intervals are separated by a middle tight unit; diagenetically dolomitized in west southern Alberta; Lower porous zone is defined as Elkton Member 110 m (360 ft) [5]
Shunda Formation Tournaisian to Visean argillaceous limestone and dolomite, siltstone, sandstone, shale, breccia, anhydrite 122 m (400 ft) [6]
Pekisko Formation Tournaisian Upper Pekisko - lithographic limestone
Lower Pekisko - massive crinoidal limestone		 134 m (440 ft) [7]

Deep basin

Sub-unit Age Lithology Max.
Thickness		 Reference
Debolt Formation Meramecian Upper Debolt - crystalline dolomite, anhydrite, micritic limestone
Lower Debolt - cherty bioclastic (crinoidal) limestone, argillaceous in the north		 366 m (1,200 ft) [8]
Prophet Formation middle Tournaisian to late Visean chert, skeletal to ooid limestone, shale, marlstone, dolomite 760 m (2,490 ft) [9]

References

  1. ^ a b c d e Lexicon of Canadian Geologic Units. "Rundle Group". Retrieved 2009-02-12.
  2. ^ Douglas, R.J.W., 1953b. Carboniferous stratigraphy in the southern Foothills of Alberta; Alberta Soc. Petrol. Geol., 3rd Ann. Field Conf. Guidebook, p. 66–88.
  3. ^ Lexicon of Canadian Geologic Units. "Mount Head Formation". Retrieved 2009-02-12.
  4. ^ Lexicon of Canadian Geologic Units. "Livingstone Formation". Retrieved 2009-02-12.
  5. ^ Lexicon of Canadian Geologic Units. "Turner Valley Formation". Retrieved 2009-02-12.
  6. ^ Lexicon of Canadian Geologic Units. "Shunda Formation". Retrieved 2009-02-12.
  7. ^ Lexicon of Canadian Geologic Units. "Pekisko Formation". Retrieved 2009-02-12.
  8. ^ Lexicon of Canadian Geologic Units. "Debolt Formation". Retrieved 2009-02-12.
  9. ^ Lexicon of Canadian Geologic Units. "Prophet Formation". Retrieved 2009-02-12.