Lyleton Formation, Three Forks Group

Unit Name: Lyleton Formation, Three Forks Group
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Disused
Age Interval: Famennian (372.2 - 358.9 ma)
Province/Territory: Manitoba

Originator: Allan, J.D. and Kerr, L.B., 1950.

Type Locality:

Robert Moore No. 1 well, in 5-20-1-27WPM, in southwestern Manitoba, between 1,244 and 1,268 m (4,080 and 4,160 ft) (Baillie, 1953). The name is applied only in the Manitoba portion of the Williston Basin.

Distribution:

The Lyleton comprises an eastward thinning sedimentary wedge with its thickness controlled primarily by pre-Mississippian erosion. The unit ranges from about 38 m (125 ft) at the Saskatchewan border to 8 m (26 ft) at the eastern erosional limit, where Lyleton red beds subcrop beneath red beds of the Middle Jurassic (?) Amaranth Formation. Several occurrences of thickened Lyleton beds (up to 55 m, 180 ft) occur near the solution edge of the Devonian Prairie Evaporite, where salt solution during Bakken-Lyleton time has caused depositional thickening.

Lithology:

Consists of red to brownish red, dolomitic and slightly silty shale and argillaceous dolomite, locally reduced to shades of medium greenish grey; minor anhydrite and local interbeds of intraformational breccia are common.

Relationship:

The Lyleton red beds conformably and sharply overlie the clean carbonates of the Birdbear (Nisku) Formation. The top of the Lyleton is marked by a gentle angular unconformity, resulting in an eastward truncation of the unit beneath the siltstones of the middle Bakken Formation. Locally, in areas of Late Devonian to Early Mississippian salt solution, thickened Lyleton sections are overlain by black shales of the lower Bakken. To the west, in Saskatchewan strata equivalent to the Lyleton are referred to the Torquay Formation of the Three Forks Group (Christopher, 1961), and the Lyleton is not recognizable in the thicker and more diverse lithologic assemblages.

Remark:

Replaced by Torquay Formation.

Other Citations:

Allan and Kerr, 1950; Baillie, 1953; Christopher, 1961; McCabe, 1959.

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: H .R. McCabe; Michelle Nicolas
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 26 Nov 2015