Red River Formation
Encyclopedia
The Red River Formation is a stratigraphical
unit of Upper Ordovician
age
in the Western Canadian Sedimentary Basin
.
It takes the name from the Red River of the North
, and was first described in outcrop in the Tyndall Stone
quarries and along the Red River Valley by A.F. Foerste in 1929.
. At the along the Manitoba outcrop belt, it is 150 metres (492.1 ft) thick and thins out northwards.
overlain by the Stony Mountain Formation
and sharply overlays the Winnipeg Formation in manitoba
, the Deadwood Formation in western Saskatchewan
and the Canadian Shield
in northern Manitoba.
The lower Red River Formation is equivalent to the Yeoman Formation, while the Fort Garry Member correlates with the Herald Formation
.
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
unit of Upper Ordovician
Ordovician
The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...
age
Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...
in the Western Canadian Sedimentary Basin
Western Canadian Sedimentary Basin
The Western Canadian Sedimentary Basin is a vast sedimentary basin underlying of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. It consists of a massive wedge of sedimentary rock...
.
It takes the name from the Red River of the North
Red River of the North
The Red River is a North American river. Originating at the confluence of the Bois de Sioux and Otter Tail rivers in the United States, it flows northward through the Red River Valley and forms the border between the U.S. states of Minnesota and North Dakota before continuing into Manitoba, Canada...
, and was first described in outcrop in the Tyndall Stone
Tyndall Stone
Tyndall stone is a dolomitic limestone quarried from the Selkirk member of the Ordovician Red River Formation, in the vicinity of Tyndall, Manitoba, Canada. It was first used in 1832 for building Lower Fort Garry, and has since become popular for building purposes throughout Canada and the United...
quarries and along the Red River Valley by A.F. Foerste in 1929.
Subdivisions
The Red River Formation is composed of the following subdivisions from top to base:- Fort Garry Member: crystalline and micritic dolomiteDolomiteDolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
with a argillaceous dolomite brecciaBrecciaBreccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix, that can be either similar to or different from the composition of the fragments....
in the middle - Selkirk Member: fossiliferous dolomitic limestoneLimestoneLimestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
- Cat Head Member: chertChertChert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
y dolomiteDolomiteDolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
, becoming calcareous to the south - Dog Head Member: fossiliferous dolomitic limestoneLimestoneLimestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
Distribution
The Red River Formation reaches a maximum thickness of 215 metres (705.4 ft) in the center of the Williston BasinWilliston Basin
The Williston Basin is a large intracratonic sedimentary basin in eastern Montana, western North and South Dakota, and southern Saskatchewan known for its rich deposits of petroleum and potash. The basin is a geologic structural basin but not a topographic depression; it is transected by the...
. At the along the Manitoba outcrop belt, it is 150 metres (492.1 ft) thick and thins out northwards.
Relationship to other units
The Red River Formation is slightly unconformablyUnconformity
An unconformity is a buried erosion surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe...
overlain by the Stony Mountain Formation
Stony Mountain Formation
The Stony Mountain Formation is a stratigraphical unit of Ashgill age in the Western Canadian Sedimentary Basin.It takes the name from the community Stony Mountain, Manitoba, and was first described in the town quarry by D.B...
and sharply overlays the Winnipeg Formation in manitoba
Manitoba
Manitoba is a Canadian prairie province with an area of . The province has over 110,000 lakes and has a largely continental climate because of its flat topography. Agriculture, mostly concentrated in the fertile southern and western parts of the province, is vital to the province's economy; other...
, the Deadwood Formation in western Saskatchewan
Saskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....
and the Canadian Shield
Canadian Shield
The Canadian Shield, also called the Laurentian Plateau, or Bouclier Canadien , is a vast geological shield covered by a thin layer of soil that forms the nucleus of the North American or Laurentia craton. It is an area mostly composed of igneous rock which relates to its long volcanic history...
in northern Manitoba.
The lower Red River Formation is equivalent to the Yeoman Formation, while the Fort Garry Member correlates with the Herald Formation
Herald Formation
The Herald Formation is a stratigraphical unit of Late Ordovician age in the Western Canadian Sedimentary Basin.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.-Lithology:The Herald Formation...
.