Unit Name: Tathlina Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Late Devonian (385.3 - 359.2 ma)
Age Justification: A brachiopod has been recovered from surface exposures.
Province/Territory: Alberta; Northwest Territories
Originator: Belyea and McLaren, 1962.
Type Locality:
Briggs Tathlina Lake No. 3 well, 60 deg 40'49"N, 117 deg 31'9.56"W, between 103.6 to 237.7 m (340 to 780 ft).
Distribution:
Type section is 134 m (440 ft) thick. It ranges from approximately 91 m (280 ft) to 134 m (440 ft) thick. It outcrops on Hay River 4.2 km (2.5 mi) to 6.4 km (4 mi) upstream from Grumbler Rapids. It occupies a narrow belt between the Tathlina Lake area and the Peace River west of Fort Vermilion, Alberta. It grades into shales of the Fort Simpson Fm to the west of the 116 th meridian and is truncated to the northeast by pre-Cretaceous erosion. It is not mappable south of 58 deg 30'N, 116 deg W where the underlying Twin Falls Fm grades to shales.
Locality Data:
Thickness(m): Minimum 91, Maximum 134, Typical 134.
Lithology:
Grey, calcareous siltstones, silty and sandy mudstones; limestones, fossiliferous; underlain in descending stratigraphic order by: micaceous siltstones with interbedded greenish-grey to grey shales; silty limestones and siltstones; and greenish-grey to grey shales.
Relationship:
The Tathlina Fm overlies the Twin Falls Fm and is overlain by the Redknife Fm. It grades westward into the Fort Simpson Fm. It correlates with a dolomite-siltstone unit that overlies the Grosmont in north-central Alberta and may be equivalent to thickened Winterburn and/ or upper Woodbend.
Other Citations:
Belyea, 1964; Belyea and McLaren, 1962; Douglas et al., 1970.
References:
Belyea, H.R. and McLaren, D.J., 1962. Upper Devonian formations, southern part of Northwest Territories, northeastern British Columbia and northwestern Alberta; Geological Survey of Canada, Paper 61-29, 74 p.
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: H.R. Balkwill; D.W. Morrow
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 13 Mar 2009