The Herald Formation is a
stratigraphic unit
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features ( facies) that characteriz ...
of
Late Ordovician
The Late Ordovician is the third and final epoch of the Ordovician period, lasting million years and spanning from around 458.2 to 443.1 million years ago. The rocks associated with this epoch are referred to as the Upper Ordovician Series.
At ...
age
Age or AGE may refer to:
Time and its effects
* Age, the amount of time someone has been alive or something has existed
** East Asian age reckoning, an Asian system of marking age starting at 1
* Ageing or aging, the process of becoming older
...
in the
Western Canadian Sedimentary Basin
The Western Canada Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary b ...
.
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.
[Saskatchewan Geological Society, 1958. Report of the Lower Paleozoic Names and Correlation Committee, Regina.]
Lithology
The Herald Formation is composed of
dolomitic limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
and
dolomite, which can be microcrystalline, argillaceous or microlaminated.
[
]
In the centre of the basin, it is represented by
anhydrite
Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the ...
.
Distribution
The Herald Formation reaches a maximum thickness of in the
Lake Alma area.
[
]
Relationship to other units
The Herald Formation is disconformably overlain by the Stony Mountain Formation and conformably overlays the Yeoman Formation.[
It can be correlated with the Fort Garry Member of the Red River Formation in ]Manitoba
Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...
and in the Williston Basin
The Williston Basin is a large intracratonic sedimentary basin in eastern Montana, western North Dakota, South Dakota, southern Saskatchewan, and south-western Manitoba that is known for its rich deposits of petroleum and potash. The basin is a ...
.
Subdivisions
In south-eastern Saskatchewan
Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...
, the formation is divided in three units, corresponding to three sedimentation cycles:
* Lake Alma Member
* Coronach Member
* Redvers Unit
References
{{Western Canadian Sedimentary Basin, Saskatchewan=yes
Geologic formations of Saskatchewan
Ordovician Saskatchewan
Western Canadian Sedimentary Basin
Limestone formations of Canada
Dolomite formations of Canada