Fernie Formation

Fernie Formation (Group)
Stratigraphic range: Jurassic

Fernie shales are 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 Morrissey Formation, 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
Coordinates 49°33′N 115°10′W / 49.55°N 115.16°WCoordinates: 49°33′N 115°10′W / 49.55°N 115.16°W
Region  Alberta,  British Columbia
Country  Canada
Type section
Named for Fernie, British Columbia
Named by Leach, 1914.

The Fernie Formation is a stratigraphic unit of Jurassic age. It is present in the western part of the Western Canada Sedimentary Basin in western Alberta and northeastern British Columbia.[2][3] In some interpretations it has Group status. It takes its name from the town of Fernie, British Columbia, and was first defined by Leach in 1914.[4]

Depositional history

The Fernie Formation is a marine unit that was deposited in the Western Interior Seaway. Deposition took place throughout most of the Jurassic period, from the Hettangian stage to the mid-Tithonian. The age is based on its fossil content, including ammonites, molluscs and microfossils.[3]

The sediments were sourced from the east during the deposition of the lower and middle units of the Fernie, where the coarser facies occur in the eastern part of the formation. In the uppermost Fernie, the coarsest material is found in the west, however, indicating a shift to sources in the west and south.[1][5]

Lithology

The Fernie Formation is composed primarily of brown and dark gray to black shales that range from massive with conchoidal fracture to laminated and highly fractured or papery. Phosphatic sandstone and limestone, including cherty limestone, occur locally in the lower parts of the formation; siltstone, sandstone, coquinas and oolitic limestone interbeds can occur in the center; glauconitic sandstone and siltstone can be present in the upper parts.[1][5]

Distribution

The Fernie Formation reaches a maximum thickness of 400 metres (1,310 ft) near Mount Allan in Alberta, and typically is about 70 to 150m thick. It thins toward the east, disappearing at about the longitude of Calgary. The formation is exposed in outcrops in the Kootenay region of southeastern British Columbia, in the foothills and front ranges of the Canadian Rockies in southwestern Alberta, and as far north as the Peace River Country in northeastern British Columbia.[1][5]

Relationship to other units

The Fernie Formation is conformably overlain by the Morrissey Formation in the south, by the Nikanassin Formation in central Alberta and by the Monteith Formation in northeastern British Columbia. It rests disconformably on Triassic units in the west, and unconformably on upper Paleozoic units such as the Schooler Creek Group and the Montney Formation farther east.[1][5]

Subdivisions

The Fernie Group has the following subdivisions from top to base:

Sub-unit Age Lithology Reference
Passage Beds Oxfordian to Tithonian dark grey splintery shale interbedded with siltstone [6][3]
Ribbon Creek Member Bathonian silty shale [7]
Green Beds Oxfordian glauconitic sandstone and siltstone, calcareous concretions, various fossils [8]
Grey Beds shale
Gryphaea Bed Bathonian coquina with Gryphaea impressimarginata, ammonites and belemnites, calcareous siltstone [9]
Corbula munda Beds Bathonian silty shale, calcareous sandstone [10]
Pigeon Creek Member Callovian calcareous siltstone and grey shale [11]
Highwood Member Bajocian dark grey shale, bioturbated sandstone [12]
Rock Creek Member Bajocian also called "Belemnite zone" - sandstone which may contain commercial gas reserves [13]
Lille Member Bajocian coquina with Gryphaea and Ostrea [14]
Poker Chip Shale Toarcian papery shale [15]
Red Deer Member Pliensbachian black shale, black laminated limestone [16]
Oxytoma Bed Sinemurian [17]
Nordegg Member Sinemurian dark chert, phosphate limestone, silty shale [18]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Lexicon of Canadian Geologic Units. "Fernie Formation". Retrieved 2009-02-10.
  2. ↑ Mossop, G.D. and Shetsen, I., (compilers), Canadian Society of Petroleum Geologists and Alberta Geological Survey (1994). "The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 18: Jurassic and Lowermost Cretaceous strata of the Western Canada Sedimentary Basin". Retrieved 2013-08-01.
  3. ↑ 3.0 3.1 3.2 Poulton, T.P., Tittemore, J. and Dolby, G. 1990. Jurassic strata of northwestern (and west-central) Alberta and northeastern British Columbia. Bulletin of Canadian Petroleum Geology 38A: 159-175.
  4. ↑ Leach, W.W., 1914. Blairmore map-area, Alberta; Geological Survey of Canada, Summary Report 1912, p. 234. with Map 107A, Blairmore, Alberta, Scale: 1 inch to 2 miles
  5. ↑ 5.0 5.1 5.2 5.3 Glass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. ISBN 0-920230-23-7.
  6. ↑ Lexicon of Canadian Geologic Units. "Passage Beds". Retrieved 2009-02-11.
  7. ↑ Lexicon of Canadian Geologic Units. "Ribbon Creek Member". Retrieved 2009-02-11.
  8. ↑ Lexicon of Canadian Geologic Units. "Green Beds". Retrieved 2009-02-11.
  9. ↑ Lexicon of Canadian Geologic Units. "Gryphaea Bed". Retrieved 2009-02-11.
  10. ↑ Lexicon of Canadian Geologic Units. "Corbula munda Beds". Retrieved 2009-02-11.
  11. ↑ Lexicon of Canadian Geologic Units. "Pigeon Creek Member". Retrieved 2009-02-11.
  12. ↑ Lexicon of Canadian Geologic Units. "Highwood Member". Retrieved 2009-02-11.
  13. ↑ Lexicon of Canadian Geologic Units. "Rock Creek Member". Retrieved 2009-02-11.
  14. ↑ Lexicon of Canadian Geologic Units. "Lille Member". Retrieved 2009-02-11.
  15. ↑ Lexicon of Canadian Geologic Units. "Poker Chip Shale". Retrieved 2009-02-11.
  16. ↑ Lexicon of Canadian Geologic Units. "Red Deer Member". Retrieved 2009-02-11.
  17. ↑ Lexicon of Canadian Geologic Units. "Oxytoma Bed". Retrieved 2009-02-11.
  18. ↑ Lexicon of Canadian Geologic Units. "Nordegg Member". Retrieved 2009-02-11.