Kotcho Formation
The Kotcho Formation is a stratigraphical unit of middle Famennian age in the Western Canadian Sedimentary Basin.
| Kotcho Formation Stratigraphic range: Middle Famennian | |
|---|---|
| Type | Geological formation |
| Underlies | Exshaw Formation |
| Overlies | Tetcho Formation |
| Thickness | up to 210.9 metres (690 ft)[1] |
| Lithology | |
| Primary | Shale |
| Other | Limestone |
| Location | |
| Coordinates | 60.15500°N 121.30444°W |
| Region |  British Columbia Northwest Territories |
| Country | .svg.png.webp){kind=small} Canada |
| Type section | |
| Named for | Kotcho Lake |
| Named by | H.R. Belyea, D.J. McLaren, 1962 |
It takes the name from Kotcho Lake, and was first described in the Imperial Island River No. 1 by H.R. Belyea and D.J. McLaren in 1962.[2]
Lithology
The Kotcho Formation is composed of green-grey shale, locally bituminous, with thin argillaceous limestone beds or lenses. [1]
Distribution
The Kotcho Formation reaches a maximum thickness of 210.9 metres (690 ft).[1]It is up to 30 metres (100 ft) thick in the Fort Nelson area, and thins down southwards, disappearing completely on the northern flank of the Peace River Arch.
Relationship to other units
The Kotcho Formation is overlain by the Exshaw Formation and conformably overlays the Tetcho Formation.[1]
To the east, it grades into the upper Wabamun Group carbonate, and to the south-west into the Palliser Formation. To the east it is replaced by the Besa River Formation shale.
References
- Lexicon of Canadian Geologic Units. "Kotcho Formation". Retrieved 2009-03-01.
- Belyea, H.R. and McLaren, D.J., 1962. Upper Devonian formations, southern pan of Northwest Territories, northeastern British Columbia and northwestern Alberta. Geological Survey of Canada, Paper 61-29.