Ishbel Group
| Ishbel Group | |
|---|---|
| Stratigraphic range: | |
 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
- ^ a b c d Lexicon of Canadian Geologic Units. "Ishbel Group". Retrieved 2010-01-01.
- ^ McGugan, A., 1963. A Permian brachiopod and fusulinid fauna from Elk Valley, British Columbia, Canada. Journal of Paleontology, v. 37, p. 621-627.
- ^ Journal of Paleontology. "Biostratigraphy and faunas of the Permian Ishbel Group, Canadian Rocky Mountains". Retrieved 2010-01-10.
- ^ Lexicon of Canadian Geologic Units. "Kindle Formation". Retrieved 2010-01-09.
- ^ Lexicon of Canadian Geologic Units. "Belloy Formation". Retrieved 2010-01-09.
- ^ Lexicon of Canadian Geologic Units. "Fantasque Formation". Retrieved 2010-01-09.
- ^ Lexicon of Canadian Geologic Units. "Mowitch Formation". Retrieved 2010-01-09.
- ^ Lexicon of Canadian Geologic Units. "Ranger Canyon Formation". Retrieved 2010-01-09.
- ^ Lexicon of Canadian Geologic Units. "Ross Creek Formation". Retrieved 2010-01-09.
- ^ Lexicon of Canadian Geologic Units. "Telford Formation". Retrieved 2010-01-09.
- ^ Lexicon of Canadian Geologic Units. "Johnston Canyon Formation". Retrieved 2010-01-09.
- ^ Lexicon of Canadian Geologic Units. "Belcourt Formation". Retrieved 2010-01-09.