| Fernie Formation (Group) Stratigraphic range: Jurassic |
|
|---|---|
Fernie shales exposed in the mountains near Fernie |
|
| Type | Geological formation |
| Sub-units | Nordegg Member, Red Deer Member, Poker Chip Shale, Lille Member, Rock Creek Member, Highwood Member, Pigeon Creek Member, Ribbon Creek Member |
| Underlies | Weary Ridge Member, Nikanassin Formation, Monteith Formation |
| Overlies | Schooler Creek Group, Montney Formation, Rundle Group |
| Thickness | up to 400 metres (1,310 ft)[1] |
| Lithology | |
| Primary | Shale |
| Other | Sandstone, siltstone, limestone |
| Location | |
| Named for | Fernie, British Columbia |
| Named by | Leach, 1914. |
| Region | Alberta, British Columbia |
| Country | Canada |
The Fernie Formation is a stratigraphical unit of Jurassic age in the Western Canadian Sedimentary Basin. In some interpretation it has Group status.
It takes the name from the town of Fernie, British Columbia, and was first defined by Leach in 1914.[2]
Contents |
The Fernie Formation is composed of brown and dark gray and black shale which can be fractured of papery. Phosphatic sandstone and limestone, as well as cherty limestone occur locally in the lower parts of the formation; siltstone, sandstones, coquinas and oolitic limestone interbeds can occur in the middle; glauconitic sandstone and siltstone can be present in the upper parts. The facies becomes transgressional at the top towards the eastern reaches of the formation, the direction from where most of the sediments originated. Five depositional cycles can be recognized within the formation.[1]
The Fernie Formation reaches a maximum thickness of 400 metres (1,310 ft) near Mount Allan, and typically has 70 to 150m. It thins out toward the east, and disappears at the longitude of Calgary.[1] The formation is exposed in outcrops in south-eastern British Columbia in the Kootenays region, in the foothills and front ranges of the Canadian Rockies in southern Alberta and as far north as the Peace River Country in north-western British Columbia
The Fernie Formation is conformably overlain by the Weary Ridge Member of the Morrissey Formation in the south, by the Nikanassin Formation in central Alberta and by the Monteith Formation in north-eastern British Columbia.[1] It disconformably overlays the Triassic of upper Paleozoic units such as the Schooler Creek Group or the Montney Formation.
The Fernie Group has the following sub-divisions from top to base:
| Sub-unit | Age | Lithology | Reference |
|---|---|---|---|
| Passage Beds | Oxfordian to Portlandian | dark grey splintery shale, silty beds | [3] |
| Ribbon Creek Member | Bathonian | silty shale | [4] |
| Green Beds | Oxfordian | glauconitic sandstone and siltstone, calcareous concretions, various fossils | [5] |
| Grey Beds | shale | ||
| Gryphaea Bed | Bathonian | coquina with Gryphaea impressimarginata, ammonites and belemnites, calcareous siltstone | [6] |
| Corbula munda Beds | Bathonian | silty shale, calcareous sandstone | [7] |
| Pigeon Creek Member | Callovian | calcareous siltstone and grey shale | [8] |
| Highwood Member | Bajocian | dark grey shale, bioturbated sandstone | [9] |
| Rock Creek Member | Bajocian | also called "Belemnite zone" - sandstone which may contain commercial gas reserves | [10] |
| Lille Member | Bajocian | coquina with Gryphaea and Ostrea | [11] |
| Poker Chip Shale | Toarcian | papery shale | [12] |
| Red Deer Member | Pliensbachian | black shale, black laminated limestone | [13] |
| Oxytoma Bed | Sinemurian | [14] | |
| Nordegg Member | Sinemurian | dark chert, phosphate limestone, silty shale | [15] |