Ishbel Group

Ishbel Group
Stratigraphic range: Permian

Calcareous siltstone exposed along the Johnston Creek west of Banff
Type Geological formation
Underlies Spray River Group
Overlies Tunnel Mountain Formation, Kananaskis Formation
Thickness up to 427 metres (1,400 ft)[1]
Lithology
Primary Carbonate, sandstone
Other Chert, siltstone
Location
Region WCSB
Country  Canada
Type section
Named for Mount Ishbel
Named by A. McGugan, 1963

The Ishbel Group is a stratigraphical unit of Permian age in the Western Canadian Sedimentary Basin.

It was first defined by A. McGugan in 1963.[2] It is named for Mount Ishbel of the Sawback Range, and parts of the group were first described in the vicinity of the mountain (Ranger Canyon, Johnston Canyon).

Lithology

The Ishbel Group is composed of carbonate, sandstone, chert and siltstone. [1]

Paleontology

The Ishbel Group was laid down under Phosphoria depositional conditions;[3] among the fossils that can be found are productid, chonetid and spiriferid brachiopods, omphalotrochid gastropod and edestid elasmobranch fish.

Distribution

The Ishbel Group reaches a maximum thickness of 427 metres (1,400 ft).[1] It occurs in the front ranges of the Canadian Rockies as far north as the Peace River.

Subdivisions

Sub-unit Age Lithology Max.
Thickness 		Reference
Kindle Formation Asselian to early Artinskian siltstone, shale 200 m (660 ft) [4]
Belloy Formation Permian carbonate and sandstone 274 m (900 ft) [5]
Fantasque Formation Permian spicular chert, shale and siltstone 55 m (180 ft) [6]
Mowitch Formation Roadian to Wordian sandstone with gypsum 76 m (250 ft) [7]
Ranger Canyon Formation Roadian to Wordian dark chert, silicified sandstone, evaporite 30 m (100 ft) [8]
Ross Creek Formation late Sakmarian to Artinskian shaly siltstone, calcareous siltstone, silty carbonate, phosphatic coquinas 143 m (470 ft) [9]
Telford Formation Asselian to Sakmarian sandy limestone and dolomite 259 m (850 ft) [10]
Johnston Canyon Formation late Sakmarian to Artinskian phosphate siltstone, calcareous siltstone and silty carbonate 57 m (190 ft) [11]
Belcourt Formation Asselian to Sakmarian silty dolomite with chert 130 m (430 ft) [12]

Relationship to other units

The Ishbel Group is disnconformably overlain by the Spray River Group and unconformably overlays the Tunnel Mountain Formation and the Kananaskis Formation in Kananaskis Country.[1]

It is equivalent to the Phosphoria Formation in Montana and Idaho.

References

  1. 1 2 3 4 Lexicon of Canadian Geologic Units. "Ishbel Group". Retrieved 2010-01-01.
  2. ↑ McGugan, A., 1963. A Permian brachiopod and fusulinid fauna from Elk Valley, British Columbia, Canada. Journal of Paleontology, v. 37, p. 621-627.
  3. ↑ Journal of Paleontology. "Biostratigraphy and faunas of the Permian Ishbel Group, Canadian Rocky Mountains". Retrieved 2010-01-10.
  4. ↑ Lexicon of Canadian Geologic Units. "Kindle Formation". Retrieved 2010-01-09.
  5. ↑ Lexicon of Canadian Geologic Units. "Belloy Formation". Retrieved 2010-01-09.
  6. ↑ Lexicon of Canadian Geologic Units. "Fantasque Formation". Retrieved 2010-01-09.
  7. ↑ Lexicon of Canadian Geologic Units. "Mowitch Formation". Retrieved 2010-01-09.
  8. ↑ Lexicon of Canadian Geologic Units. "Ranger Canyon Formation". Retrieved 2010-01-09.
  9. ↑ Lexicon of Canadian Geologic Units. "Ross Creek Formation". Retrieved 2010-01-09.
  10. ↑ Lexicon of Canadian Geologic Units. "Telford Formation". Retrieved 2010-01-09.
  11. ↑ Lexicon of Canadian Geologic Units. "Johnston Canyon Formation". Retrieved 2010-01-09.
  12. ↑ Lexicon of Canadian Geologic Units. "Belcourt Formation". Retrieved 2010-01-09.
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