Unit Name: Murray Ridge Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: early Sinemurian - late Sinemurian (196.5 - 189.6 ma)
Age Justification: Ammonites including Echioceras spp., brachiopods, bivalves, crinoids, palynomorphs, Foraminifera.
Province/Territory: Northwest Territories
Originator: Poulton, Leskiw and Audretsch, in press.
Type Locality:
On the western face of the north part of Murray Ridge, District of Mackenzie (68 deg 01'45"N, 136 deg 26'30"W). The type for the Scho Creek Member is on Bug Creek in the Aklavik Range, District of Mackenzie (68 deg 04'30"N, 135 deg 28'20"W).
Distribution:
It thickens westward and northward from 30 m (100 ft) in the Aklavik Range to about 80 m (265 ft) at Murray Ridge and north of White Mountains. It is widespread in the northernmost Richardson Mountains and western Mackenzie delta.
Lithology:
The Murray Ridge Fm is subdivided into two members, listed in ascending order: 1) Scho Creek Member, fine- to medium-grained, pebbly to conglomeratic sandstone with minor thin argillaceous interbeds; and 2) unnamed member, grey siltstone. Where the Scho Creek Member is absent, the basal one metre of the siltstone unit is generally ferruginous mudstone which is locally highly fossiliferous.
Relationship:
It paraconformably overlies Permian strata and is gradationally or sharply overlain by the Almstrom Creek Fm. South of a line joining Jurassic Butte (68 deg 01' 30"N, 135 deg 25'30"W) and the head of Scho Creek (67 deg 55'N, 136 deg 10'W), it is in paraconformable contact with the Richardson Mountains Fm. It corresponds to the informal "basal sandstone member" and "grey siltstone member" of the Bug Creek Fm (now Gp) of Jeletzky (1967). It is the "lower Kingak tongue" of Poulton (1978a).
Other Citations:
Jeletzky, 1967; Poulton, 1978a; Poulton et al., in press.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 2, Yukon Territory and District of Mackenzie; L.V. Hills, E.V. Sangster and L.B. Suneby (editor)
Contributor: T.P. Poulton; L.V. Hills
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 29 Apr 2003