Unit Name: Kechika Group
Unit Type: Lithostratigraphic
Age Interval: Sandbian - Trempealeaun (460.9 - 488.3 ma)
Age Justification: Graptolites are the most common fossil in the type area, and minor trilobites, brachiopods, crinoid debris, bryozoans and cephalopods have been reported. These fauna range in age from latest Cambrian (Trempealeauan) to early Late Ordovician (Gabrielse, pers comm. 1982). Tipnis (1981, and pers. comm. 1982) has identified continuous conodont zone fauna from Trempealeauan to latest Early Ordovician in both condensed eastern (mountain front) and very thick western sections of the lower Kechika Group. Mid-Continent, North American, and mixed Early Ordovician conodont elements are present.
Province/Territory: British Columbia
Originator: Gabrielse, 1963.
Kechika Ranges, southeastern McDame Map area, British Columbia.
In the type area the Kechika Group varies in the thickness from 300 to more than 600 m (984 to more than 1968 ft). In the Ware Map area it ranges from 300 to 1,400 m (984 to 4,592 ft) due to depositional factors. Kechika Group strata are reported in the McDame, Tuchodi Lakes, Toodoggone River, Ware, Crutch and Halfway River map areas. Similar homotaxial beds are described in the Mesalinka, Kechika, Cry Lake, Rabbit River, Watson Lake and Coal River map-areas.
Thickness(m): Minimum 300, Maximum 1400.
At the type locality, shale, slate, calcareous phyllite, phyllite, limestone and limestone conglomerate. In the Ware Map area (NTS 94F) the lower Kechika Group is argillaceous, often nodular limestone, limestone, very calcareous mudstone and limestone conglomerate.
In the type area the nature of the contact with the underlying Atan Group is unknown, and the contact with the overlying Sandpile Group is a disconformity. The lower Kechika Group unconformably overlies Cambrian strata in the eastern and western part of the Ware Map area, but is conformable with Upper Cambrian beds in the east-central part of the same map area. Upper Kechika Group rocks have been included in the Road River Formation in the Ware and Toodoggone River map-areas. In the Ware map-area the Road River Formation (upper Kechika Group) is conformable and partly diachronous with the lower Kechika Group. The lower Kechika Group is partly correlative with the Rabbitkettle Formation in the Selwyn Basin, and the Broken Skull and Franklin Mountain formations on the Mackenzie Platform. The upper Kechika Group is correlative with parts of the Road River Formation in the Selwyn Basin and its platform equivalents. In the southern Cordillera the lower Kechika Group is correlative with, and lithologically similar to the Survey Peak and Outram formations. The entire Kechika Group is correlative with the McKay Formation, and the upper Kechika Group with the Glenogle Formation and its platform equivalents.
First described as Walker Group (Gabrielse, 1954) but later changed to Kechika Group (Gabrielse, 1963). The Kechika Group was renamed the Kechika Formation (Pyle and Barnes, 2000).
Gabrielse, H., 1954. McDame, British Columbia (Map with Marginal Notes); Geological Survey of Canada, Paper 54-10, Scale: One Inch to Four Miles (1:253 440)).
Gabrielse, H., 1963. McDame map-area, Cassiar District, British Columbia; Geological Survey of Canada, Memoir 319, 138 p.
Pyle, L.J. and Barnes, C.R. 2000. Upper Cambrian to Lower Silurian stratigraphic framework of platform-to-basin facies, northeast British Columbia; Bulletin of Canadian Petroleum Geology, v. 48, p. 123-149.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: M.P. Cecile; M. T. Adamson; P.H. Davenport
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 16 Jan 2009