Manitoba Group
Encyclopedia
The Manitoba Group is a stratigraphical
unit of middle to late Devonian
age
in the Western Canadian Sedimentary Basin
.
It takes the name from the province of Manitoba
, and was first defined by A.D. Baillie in 1953.
, carbonate
and evaporite
.
and in the sub-surface in southern Saskatchewan
, North Dakota
and Montana
. It reaches a maximum thickness of 150 metres (492.1 ft) in outcrop and up to 244 metres (800.5 ft) in the sub-surface.
overlays the Prairie Evaporite Formation or Winnipegosis Formation of the Elk Point Group
.
The lower Manitoba Group is equivalent to the Muskeg Formation
in northern Alberta
, while the upper part correlates with the Beaverhill Lake 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 middle to late Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
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 province of 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...
, and was first defined by A.D. Baillie in 1953.
Lithology
The Manitoba Group is composed of alternating cycles of shaleShale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
, carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
and evaporite
Evaporite
Evaporite is a name for a water-soluble mineral sediment that result from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporate deposits, marine which can also be described as ocean deposits, and non-marine which are found in standing bodies of...
.
Distribution
The Manitoba Group occurs in outcrop in southwestern ManitobaManitoba
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...
and in the sub-surface in southern 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....
, North Dakota
North Dakota
North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....
and Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
. It reaches a maximum thickness of 150 metres (492.1 ft) in outcrop and up to 244 metres (800.5 ft) in the sub-surface.
Subdivisions
The following formationas are recognised, from top to bottom:- The Souris River Formation appears in the upper part of the Manitoba Group, is of Givetian to FrasnianFrasnianThe Frasnian is one of two faunal stages in the Late Devonian epoch. It lasted from 385.3 ± 2.6 million years ago to 374.5 ± 2.6 million years ago. It was preceded by the Givetian stage and followed by the Famennian stage...
age and consists of thin shale-carbonate-evaporite cycles. - The Hubbard Evaporite is recognised at the top of the Montana Group in the Elk Point Basin. Its age is Givetian
- The Dawson Bay Formation is the lower part of the Manitoba Group. It is of Givetian age and consists of red shale (the "Second Red Bed") and a sequence of 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....
and dolomiticDolomiteDolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
limestone.
Relationship to other units
The Manitoba Group is conformably overlain by the Duperow Formation and disconformablyUnconformity
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...
overlays the Prairie Evaporite Formation or Winnipegosis Formation of the Elk Point Group
Elk Point Group
The Elk Point Group is a stratigraphical unit of Middle Devonian age in the Western Canadian Sedimentary Basin.It takes the name from the town of Elk Point, and was first described in the Anglo-Canadian Elk Point No...
.
The lower Manitoba Group is equivalent to the Muskeg Formation
Muskeg Formation
The Muskeg Formation is a stratigraphical unit of Givetian age in the Western Canadian Sedimentary Basin.It takes the name from the Muskeg arctic soil that covers the northern reaches of western Canada, and was first described in the California Standard Steen River 2-22-117-5W6M well by J...
in northern Alberta
Northern Alberta
Northern Alberta is a region located in the Canadian province of Alberta.Its primary industry is oil and gas, with large heavy oil reserves being exploited at the Athabasca Oil Sands and Wabasca Area in the east of the region...
, while the upper part correlates with the Beaverhill Lake Formation.