Ishbel Group

The Ishbel Group is a stratigraphic unit of Permian age in the Western Canadian Sedimentary Basin. It is present in the Canadian Rockies of Alberta and British Columbia. First defined by A. McGugan in 1963,[2] it is named for Mount Ishbel of the Sawback Range in Banff National Park, and parts of the group were first described in the vicinity of the mountain at Ranger Canyon and Johnston Canyon.[3]

Ishbel Group
Stratigraphic range:
Calcareous siltstone exposed along the Johnston Creek west of Banff
TypeGroup
UnderliesSpray River Group
OverliesTunnel Mountain Formation, Kananaskis Formation
ThicknessUp to about 425 m (1,394 ft)[1]
Lithology
PrimaryLimestone, dolomite, sandstone
OtherChert, siltstone
Location
Region Alberta
 British Columbia
Country Canada
ExtentWestern Canadian Sedimentary Basin
Type section
Named forMount Ishbel
Named byA. McGugan
Year defined1963

Lithology

The Ishbel Group is composed of carbonate rocks (limestone and dolomite) and sandstone, with minor chert and siltstone. [1][3] Depositional conditions were similar to those of the Phosphoria Formation to the south in United States.[3]

Paleontology

Among the fossils that have been found in the Ishbel Group are corals, bryozoa, crinoids, and conodonts,[3] as well as productid, chonetid and spiriferid brachiopods, omphalotrochid gastropods, and edestid elasmobranch fish.[4]

Distribution

The Ishbel Group reaches a maximum thickness of up to about 425 metres (1400 ft). It is present in the front ranges of the Canadian Rockies as far north as the Peace River.[1][3]

Subdivisions
Sub-unitAgeLithologyMax.
Thickness		Reference
Kindle FormationAsselian to early Artinskiansiltstone, shale200 m (660 ft) [5]
Belloy FormationPermianlimestone, dolomite, and sandstone274 m (900 ft) [6]
Fantasque FormationPermianspicular chert, shale, and siltstone55 m (180 ft) [7]
Mowitch FormationRoadian to Wordiansandstone with gypsum76 m (250 ft) [8]
Ranger Canyon FormationRoadian to Wordiandark chert, silicified sandstone, evaporite minerals30 m (100 ft) [9]
Ross Creek Formationlate Sakmarian to Artinskianshaly siltstone, calcareous siltstone, silty carbonate, phosphatic coquinas143 m (470 ft) [10]
Telford FormationAsselian to Sakmariansandy limestone and dolomite259 m (850 ft) [11]
Johnston Canyon Formationlate Sakmarian to Artinskianphosphatic siltstone, calcareous siltstone, and silty limestone and dolomite57 m (190 ft) [12]
Belcourt FormationAsselian to Sakmariansilty dolomite with chert130 m (430 ft) [13]

Relationship to other units

The Ishbel Group is disnconformably overlain by the Spray River Group and unconformably overlies the Tunnel Mountain Formation and the Kananaskis Formation.[1] It is partly equivalent to the Phosphoria Formation of Montana, Idaho, Wyoming, and Utah.[3]

References
  1. Lexicon of Canadian Geologic Units. "Ishbel Group". Retrieved 2010-01-01.
  2. McGugan, A., 1963. A Permian brachiopod and fusulinid fauna from Elk Valley, British Columbia, Canada. Journal of Paleontology, v. 37, p. 621-627.
  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.
  4. Journal of Paleontology. "Biostratigraphy and faunas of the Permian Ishbel Group, Canadian Rocky Mountains". Retrieved 2010-01-10.
  5. Lexicon of Canadian Geologic Units. "Kindle Formation". Retrieved 2010-01-09.
  6. Lexicon of Canadian Geologic Units. "Belloy Formation". Archived from the original on 2012-07-08. Retrieved 2010-01-09.
  7. Lexicon of Canadian Geologic Units. "Fantasque Formation". Retrieved 2010-01-09.
  8. Lexicon of Canadian Geologic Units. "Mowitch Formation". Retrieved 2010-01-09.
  9. Lexicon of Canadian Geologic Units. "Ranger Canyon Formation". Retrieved 2010-01-09.
  10. Lexicon of Canadian Geologic Units. "Ross Creek Formation". Retrieved 2010-01-09.
  11. Lexicon of Canadian Geologic Units. "Telford Formation". Retrieved 2010-01-09.
  12. Lexicon of Canadian Geologic Units. "Johnston Canyon Formation". Retrieved 2010-01-09.
  13. Lexicon of Canadian Geologic Units. "Belcourt Formation". Retrieved 2010-01-09.
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