Herald Formation

(Redirected from Lake Alma Member)

The Herald Formation is a stratigraphical unit of Late Ordovician age in the Western Canadian Sedimentary Basin.

Herald Formation
Stratigraphic range: Late Ordovician
TypeGeological formation
Sub-unitsLake Alma Member
Coronach Member
Redvers Unit
UnderliesStony Mountain Formation
OverliesYeoman Formation
Thicknessup to 38 metres (120 ft)[1]
Lithology
Primarylimestone, dolomite, anhydrite
Location
Coordinates49°04′29″N 104°39′08″W / 49.0746°N 104.6521°W / 49.0746; -104.6521 (Herald Formation)
RegionWCSB
Country Canada
Type section
Named bySaskatchewan Geological Society, 1958.

It was defined in well Imperial Herald 1-31-1-20W2M by the Lower Paleozoic Names and Correlations Committee of the Saskatchewan Geological Society in 1958.[2]

Lithology

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The Herald Formation is composed of dolomitic limestone and dolomite, which can be microcrystalline, argillaceous or microlaminated. [1] In the centre of the basin, it is represented by anhydrite.

Distribution

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The Herald Formation reaches a maximum thickness of 38 metres (120 ft) in the Lake Alma area.[1]

Relationship to other units

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The Herald Formation is disconformably overlain by the Stony Mountain Formation and conformably overlays the Yeoman Formation.[1]

It can be correlated with the Fort Garry Member of the Red River Formation in Manitoba and in the Williston Basin.

Subdivisions

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In south-eastern Saskatchewan, the formation is divided in three units, corresponding to three sedimentation cycles:

References

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  1. ^ a b c d Lexicon of Canadian Geologic Units. "Herald Formation". Archived from the original on 2013-02-21. Retrieved 2010-02-01.
  2. ^ Saskatchewan Geological Society, 1958. Report of the Lower Paleozoic Names and Correlation Committee, Regina.