Ishbel Group

Ishbel Group Stratigraphic range: Permian PreЄ Є O S D C P T J K Pg N
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. 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.