Английская Википедия:Fernie Formation

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Шаблон:Infobox Rockunit 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.[1][2][3] It takes its name from the town of Fernie, British Columbia, and was first defined by W.W. Leach in 1914.[4]

Depositional history

The Fernie Formation consists of marine sediments that were deposited in the Sundance Sea. Deposition took place throughout most of the Jurassic period, starting during the Hettangian stage in some parts of northeastern British Columbia and continuing until the mid-Tithonian, as determined from its fossil assemblages, including ammonites, molluscs and microfossils.[2][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.[5][6]

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.[5][6]

Distribution

The Fernie Formation reaches a maximum thickness of Шаблон:Convert near Mount Allan in Alberta, and typically is about 70 to 150m (230 to 492 ft) 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.[5][6]

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.[5][6]

Subdivisions

The Fernie Formation 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 [7][2]
Ribbon Creek Member Bathonian silty shale [8]
Green Beds Oxfordian glauconitic sandy mudstone, calcareous and phosphatic concretions [9][3]
Grey Beds Callovian dark platy shale with ammonites and concretions [3]
Gryphaea Bed Bathonian coquina with shells of Gryphaea impressimarginata, ammonites and belemnites; calcareous siltstone [10]
Corbula munda Beds Bathonian silty shale, calcareous sandstone [11]
Pigeon Creek Member Callovian calcareous siltstone and grey shale [12]
Highwood Member Bajocian dark grey shale, bioturbated sandstone [13]
Rock Creek Member Bajocian also called "Belemnite zone" - fine-grained grey sandstone that may contain commercial gas reserves [14][3]
Lille Member Bajocian coquina with Gryphaea and Ostrea shells [15]
Poker Chip Shale Toarcian fissile black calcareous shale, thin-bedded black argillaceous limestone [16][3]
Red Deer Member Pliensbachian black shale, black laminated limestone [17]
Oxytoma Bed Sinemurian coquina with Oxytoma shells [18]
Nordegg Member Sinemurian dark cherty and phosphatic limestone, calcareous shale [19][3]

See also

References

Шаблон:Reflist Шаблон:WCSB

Партнерские ресурсы
Криптовалюты
Магазины
Хостинг
Разное

  1. ↑ Шаблон:Cite web
  2. ↑ 2,0 2,1 2,2 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.
  3. ↑ 3,0 3,1 3,2 3,3 3,4 3,5 3,6 Stott, D.F. 1998. Fernie Formation and Minnes Group (Jurassic and lowermost Cretaceous), northern Rocky Mountain foothills, Alberta and British Columbia. Geological Survey of Canada, Bulletin 516.
  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 Ошибка цитирования Неверный тег <ref>; для сносок lexicon не указан текст
  6. ↑ 6,0 6,1 6,2 6,3 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. Шаблон:ISBN.
  7. ↑ Шаблон:Cite web
  8. ↑ Шаблон:Cite web
  9. ↑ Шаблон:Cite web
  10. ↑ Шаблон:Cite web
  11. ↑ Шаблон:Cite web
  12. ↑ Шаблон:Cite web
  13. ↑ Шаблон:Cite web
  14. ↑ Шаблон:Cite web
  15. ↑ Шаблон:Cite web
  16. ↑ Шаблон:Cite web
  17. ↑ Шаблон:Cite web
  18. ↑ Шаблон:Cite web
  19. ↑ Шаблон:Cite web
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