Prairie Evaporite Formation
| Prairie Evaporite Formation | |
|---|---|
| Stratigraphic range: | |
Winnipegosis Formation | |
| Thickness | Up to 300 metres (980 ft)[1] |
| Lithology | |
| Primary | Halite, anhydrite |
| Other | dolomite, mudstone |
| Location | |
| Region |  Alberta  Saskatchewan Manitoba  North Dakota Montana |
| Country |  Canada  United States |
| Type section | |
| Named by | A.D. Baillie (1953)[2] |
The Prairie Evaporite Formation, also known as the Prairie Formation, is a
The formation is a major source of potash, most of which is used for fertilizer production.[5][6] Salt is also produced from the formation,[7] and solution caverns are created in its thick salt beds for natural gas storage.[8]
Lithology
The Prairie Evaporite Formation consists thick beds of halite, with interbeds of
Environment of Deposition
The Prairie Evaporite Formation was deposited in an
Groundwater has gained access to Prairie Evaporite Formation along its eastern and southern margins, dissolving the halite and other soluble minerals. That process, which is ongoing today, produced a breccia that consists of fragments of overlying formations that collapsed when their support was removed, as well as insoluble material from within the Prairie Evaporite itself.[1][3]
Distribution, Thickness and Depth
The Prairie Evaporite Formation is present in the subsurface in the Western Canada and Williston sedimentary basins, extending from northern Alberta to northern North Dakota, a distance of more than 1,500 kilometres (930 mi). It reaches thicknesses of more than 200 metres (660 ft) near Saskatoon in Saskatchewan,[5] and more than 300 metres (980 ft) north of Fort McMurray in Alberta.[1]
The formation is nowhere exposed in
Stratigraphy
The Prairie Evaporite Formation is part of the Elk Point Group and was named by A.D. Baillie in 1953 based on a core from a well (Imperial Davidson No. 1, 16-8-27-1W3) that was drilled in southern Saskatchewan.[2] There are no geophysical well logs for that core, however, and some intervals were removed for analysis, so in 1969 M.E. Holter designated a more complete reference section from another well (White Rose et al. Drake 4-29-32-22W2) to supplement it.[5][11]
The formation is usually divided into three members in Alberta. The Whitkow Member at the base, which is present locally in the deepest parts of the basin, consists of coarsely crystalline halite with minor anhydrite. The overlying Shell Lake Member consists primarily of anhydrite interbedded with dolomite. The Leofnard Member at the top consists of halite with minor interbeds of dolomite, anhydrite and mudstone.[5][9]
Additional units are present in the potash-bearing areas of Saskatchewan and North Dakota. They overlie, or are considered to be submembers of, the Leofnard Member.[9] From base to top, they are the Esterhazy, White Bear, Belle Plaine, Patience Lake Members[5][7] which, in North Dakota, are overlain by the Mountrail and White Lake Members.[4] They are separated by unnamed zones of halite.[4][7]
Relationship to Other Units
The contact between the Prairie Evaporite Formation and the underlying
The northern limit of the formation occurs at about 58° north latitude in Alberta, where the Prairie Evaporite grades into the anyhdritic Muskeg Formation through a decrease in its halite content and an increase in its anhydrite content. Along its eastern and southern margins the formation grades into the breccia that results from the dissolution of its halite and anhydrite. Along its western margin it thins to zero at its depositional limit.[1][3]
Economic Significance
Potash and Salt
In Saskatchewan,
Salt is produced primarily as a byproduct of potash mining. For practical purposes, the salt reserves of the Prairie Evaporite Formation are essentially unlimited.[7]
Petroleum and Natural Gas
The thick halite beds of the Prairie Evaporite Formation are essentially
References
- ^ a b c d e f Grobe, M. Alberta Energy and Utilities Board, EUB/AGS Earth Sciences Report 2000-02 (2000). "Distribution and thickness of salt within the Devonian Elk Point Group, Western Canada Sedimentary Basin" (PDF). Retrieved 2015-03-26.
{{cite web}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link) - ^ a b Baillie, A.D. 1953. Devonian system of the Williston Basin area. Manitoba Mines Branch, Publication 52-5.
- ^ a b c d Mossop, G.D. and Shetsen, I. (compilers). Canadian Society of Petroleum Geologists and Alberta Geological Survey (1994). "The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 10: Devonian Elk Point Group of the Western Canada Sedimentary Basin". Archived from the original on 2016-07-01. Retrieved 2016-06-20.
{{cite web}}: CS1 maint: multiple names: authors list (link) - ^ a b c d e Kruger, N. North Dakota Geological Survey, Report of Investigations No. 113 (2014). "The potash members of the Prairie Formation in North Dakota" (PDF). Retrieved 2015-12-30.
{{cite web}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link) - ^ a b c d e f Holter, M.E. 1969. The Middle Devonian Prairie Evaporite of Saskatchewan. Saskatchewan Department of Mineral Resources, Report No. 123.
- ^ Burton, J. University of Regina and Canadian Plains Research Center (2007). "Potash industry". Retrieved 2015-12-30.
- ^ a b c d e Harper, C.T. (editor) 2003. Geology, and mineral and petroleum resources of Saskatchewan. Saskatchewan Industry and Resources, Saskatchewan Geological Survey, Miscellaneous Report 2003-7, 173 p.
- ^ a b Crossley, N.G. 1998. Conversion of LPG salt caverns to natural gas storage, "A TransGas Experience". Journal of Canadian Petroleum Technology, v. 37, no. 12, p. 37-47.
- ^ a b c Meijer Drees, N.C. 1986. Evaporitic deposits of western Canada. Geological Survey of Canada, Paper 85-20.
- ^ Rouchy, J.M. and Caruso, A. 2006. The Messinian salinity crisis in the Mediterranean basin: A reassessment of the data and an integrated scenario. Sedimentary Geology 188-189, p. 36-67.
- ^ ISBN 0-920230-23-7.