| 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 | |
| Named for | Mount Ishbel |
| Named by | A. McGugan, 1963 |
| Region | WCSB |
| Country | Canada |
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).
Contents |
The Ishbel Group is composed of carbonate, sandstone, chert and siltstone. [1]
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.
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.
| 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] |
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.
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