Ishbel Group
Introduction 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, 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.
Lithology The Ishbel Group is composed of carbonate rocks (limestone and dolomite) and sandstone, with minor chert and siltstone. Depositional conditions were similar to those of the Phosphoria Formation to the south in United States.
Paleontology Among the fossils that have been found in the Ishbel Group are corals, bryozoa, crinoids, and conodonts, as well as productid, chonetid and spiriferid brachiopods, omphalotrochid gastropods, and edestid elasmobranch fish.
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.
Subdivisions  Sub-unit  Age  Lithology  Max.Thickness  ReferenceKindle Formation  Asselian to early Artinskian  siltstone, shale  Belloy Formation  Permian  limestone, dolomite,  and sandstone  Fantasque Formation  Permian  spicular chert, shale, and siltstone  Mowitch Formation  Roadian to Wordian  sandstone with gypsum  Ranger Canyon Formation  Roadian to Wordian  dark chert, silicified sandstone, evaporite minerals  Ross Creek Formation  late Sakmarian to Artinskian  shaly siltstone, calcareous siltstone, silty carbonate, phosphatic coquinas  Telford Formation  Asselian to Sakmarian  sandy limestone and dolomite  Johnston Canyon Formation  late Sakmarian to Artinskian  phosphatic siltstone, calcareous siltstone, and silty limestone and dolomite  Belcourt Formation  Asselian to Sakmarian  silty dolomite with chert
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. It is partly equivalent to the Phosphoria Formation of Montana, Idaho, Wyoming, and Utah.
References