The formations of the Elk Point Group were deposited in a marine embayment that stretched from an open ocean in the present-day Northwest Territories of Canada to North Dakota in the United States, covering an area roughly half as large as that covered by today's Mediterranean Sea. At times of low water levels and excessive evaporation, halite and other evaporite minerals were deposited in sabkha, supratidal flat and coastal lagoon environments, and at times of higher water levels carbonate platform sedimentation and reef growth were dominant.[1][4]
The Elk Point Group was named for the town of Elk Point, Alberta by J.R. McGehee in 1949.[3]Core from a well that was drilled near Elk Point has been designated as the type section (Anglo-Canadian Elk Point No. 11, 2-11-57-5W4).[1] The group is subdivided into the Lower and Upper Elk Point Group, each of which is further subdivided into formations according to the dominant lithologies,[1][2] as shown in the tables below.
The Lower Elk Point Group comprises all strata lying below the Winnipegosis Formation (in the south) or the Keg River Formation (in the north) and is present only in the deepest parts of the basin. The Upper Elk Point Group, which is present throughout the basin, includes those formations and all overlying formations to the base of the Manitoba Group (in the south) or the Beaverhill Lake Group (in the north).[1]
The Elk Point Group is conformably overlain by the Manitoba Group in Manitoba and Saskatchewan, and by the Beaverhill Lake Group in Alberta. It rests unconformably on Precambrianbasement rocks in northern Alberta, on Cambrian strata in northeastern Alberta and in Saskatchewan, and on Ordovician to Silurian[1] formations in western Alberta, Saskatchewan and southwestern Manitoba.[2] In the Northwest Territories, some of its uppermost units are exposed at surface or are unconformably overlain by Cretaceous strata.[1]
The Lower Elk Point Group is equivalent to the Stone Formation and its equivalents, and the Headless and Nahanni Formations, in northerneastern British Columbia and the southwestern Northwest Territories. In the same areas, the Upper Elk Point includes the Pine Point Group, and is equivalent to parts of the Horn River Formation, Besa River Formation, and others.[2]
Petroleum and Natural Gasedit
The porous carbonate rocks of the Elk Point Group host major petroleum and natural gasreservoirs. As of 1994, the Initial Established Recoverable Petroleum Reserves and the Cumulative Petroleum Production for the group were estimated at 339.3 and 240.4 million cubic metres, respectively. For natural gas, the Initial Established Marketable Reserves and the Cumulative Production were estimated at 142.7 and 79.5 billion cubic metres, respectively.[5]
Referencesedit
^ abcdefghMeijer Drees, N.C. 1986. Evaporitic deposits of western Canada. Geological Survey of Canada, paper 85-20.
^ abcdefghijklmnopqrstuvwxyGlass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. ISBN0-920230-23-7.
^ abMossop, 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". Retrieved 2016-06-20.{{cite web}}: CS1 maint: multiple names: authors list (link)
^ abcMossop, G.D. and Shetsen, I. (compilers) Canadian Society of Petroleum Geologists (1994). "The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 32: Oil and Gas Resources of the Western Canada Sedimentary Basin". Retrieved 2016-06-20.{{cite web}}: CS1 maint: multiple names: authors list (link)
^Schneider, C.L.; Grobe, F.J.; Hein (2018-01-24) [2012]. "ERCB/AGS Open File Report 2012-20 Outcrops of the La Loche, Contact Rapids, and Keg River Formations (Devonian) on the Clearwater River: Alberta (NTS 74D/9) and Saskatchewan (NTS 74C/12)" (PDF). Energy Resources Conservation Board Alberta Geological Survey. Her Majesty the Queen in Right of Alberta, 2013. ISBN978-1-4601-0089-9. Retrieved 2018-01-24.
May 10, 2024
point, group, stratigraphic, unit, early, middle, devonian, western, canada, williston, sedimentary, basins, underlies, large, area, that, extends, from, southern, boundary, northwest, territories, canada, north, dakota, united, states, been, subdivided, into,. The Elk Point Group is a stratigraphic unit of Early to Middle Devonian age in the Western Canada and Williston sedimentary basins It underlies a large area that extends from the southern boundary of the Northwest Territories in Canada to North Dakota in the United States It has been subdivided into numerous formations 4 number of which host major petroleum and natural gas reservoirs 5 Elk Point GroupStratigraphic range Early to Middle Devonian PreꞒ Ꞓ O S D C P T J K Pg NBlue halite Prairie Evaporite Formation upper Elk Point Group Middle Devonian from SaskatchewanTypeGeological formationSub unitsUpper and Lower Elk Point GroupUnderliesBeaverhill Lake Group Manitoba GroupOverliesPrecambrian to Silurian formations 1 Thicknessup to 610 metres 2 000 ft 2 LithologyPrimarydolomite halite anhydriteOtherLimestone shale potashLocationCoordinates53 54 19 N 110 37 49 W 53 9053 N 110 6304 W 53 9053 110 6304 Elk Point Group RegionNorthern plainsCountry Canada United StatesType sectionNamed forElk PointNamed byJ R McGehee 3 Contents 1 Lithology 2 Paleontology 3 Environment of Deposition 4 Distribution and Thickness 5 Stratigraphy 5 1 Subdivisions 6 Relationship to Other Units 7 Petroleum and Natural Gas 8 ReferencesLithology editThe formations of the Elk Point Group are composed primarily of carbonate rocks dolomite and limestone and evaporitic rocks halite anhydrite and potash with lesser amounts of dolomitic mudstone and shale 2 Paleontology editSome of the carbonate formations of the Elk Point Group contain rich assemblages of marine invertebrate fossils including many species of brachiopods gastropods bivalves cephalopods crinoids ostracods and corals The evaporitic formations are unfossiliferous or contain a few spores and algal remains 2 Environment of Deposition editThe formations of the Elk Point Group were deposited in a marine embayment that stretched from an open ocean in the present day Northwest Territories of Canada to North Dakota in the United States covering an area roughly half as large as that covered by today s Mediterranean Sea At times of low water levels and excessive evaporation halite and other evaporite minerals were deposited in sabkha supratidal flat and coastal lagoon environments and at times of higher water levels carbonate platform sedimentation and reef growth were dominant 1 4 Distribution and Thickness editThe Elk Point Group extends from the southern boundary of the Northwest Territories through northwestern British Columbia Alberta Saskatchewan and southwestern Manitoba in Canada and continues into eastern Montana and North Dakota in the United States 1 It reaches a maximum thickness of about 610 metres 2 000 ft in eastern Alberta 2 Stratigraphy editThe Elk Point Group was named for the town of Elk Point Alberta by J R McGehee in 1949 3 Core from a well that was drilled near Elk Point has been designated as the type section Anglo Canadian Elk Point No 11 2 11 57 5W4 1 The group is subdivided into the Lower and Upper Elk Point Group each of which is further subdivided into formations according to the dominant lithologies 1 2 as shown in the tables below The Lower Elk Point Group comprises all strata lying below the Winnipegosis Formation in the south or the Keg River Formation in the north and is present only in the deepest parts of the basin The Upper Elk Point Group which is present throughout the basin includes those formations and all overlying formations to the base of the Manitoba Group in the south or the Beaverhill Lake Group in the north 1 Subdivisions edit In northern Alberta and central Alberta the Elk Point Group contains the following subdivisions from top to base Sub unit Age Lithology Max Thickness Reference Watt Mountain Formation Givetian red and green shale sandstone anhydrite dolomite limestone 74 4 m 240 ft 2 Gilwood Member Givetian coarse quartz and feldspathic sandstone 15 2 m 50 ft 2 Presqu ile Formation Givetian crystalline dolomite 300 m 980 ft 2 Sulphur Point Formation Givetian fossiliferous limestone green shale 106 m 350 ft 2 Muskeg Formation Givetian anhydrite salt dolomite limestone 270 m 890 ft 2 Zama Member Givetian sucrosic dolomite 24 m 80 ft 2 Keg River Formation Givetian porous dolomite wackestone limestone includes the Rainbow Member dolomitized reef 300 m 980 ft 2 Contact Rapids Formation Eifelian to Givetian argillaceous dolomite dolomitic shale 48 8 m 160 ft 2 Chinchaga Formation Eifelian to Givetian anhydrite crystalline dolomite quartz sandstone dolomitic shale halite 76 m 250 ft 2 Cold Lake Formation Eifelian halite dolomitic shale 117 m 380 ft 2 Ernestina Lake Formation Eifelian red shale base carbonates anhydrite top 23 m 80 ft 2 Lotsberg Formation Eifelian halite calcareous shale 229 m 750 ft 2 La Loche Formation Basal red beds Eifelian red dolomitic or calcareous shales silty or sandy quartzose sandstone 30 m 100 ft 2 5 6 In southern Alberta The Elk Point Group is dolomitic and is not differentiated In Saskatchewan Manitoba and Montana Sub unit Age Lithology Max Thickness Reference Dawson Bay Formation Givetian dolomitic mudstone crystalline limestone argillaceous carbonate bituminous limestone dolomite anhydrite halite 50 m 160 ft 2 Prairie Evaporite Formation Givetian halite anhydrite dolomite dolomitic mudstone limestone potash 218 m 720 ft 2 Winnipegosis Formation Givetian dolomite bituminous carbonates anhydrite 100 m 330 ft 2 Ashern Formation Eifelian to Givetian argillaceous dolomite and dolomitic shale and siltstone minor anhydrite 55 m 180 ft 2 Meadow Lake Formation Eifelian dolomite with mudstone interbeds limestone and sandstone at base 56 m 180 ft 2 Relationship to Other Units editThe Elk Point Group is conformably overlain by the Manitoba Group in Manitoba and Saskatchewan and by the Beaverhill Lake Group in Alberta It rests unconformably on Precambrian basement rocks in northern Alberta on Cambrian strata in northeastern Alberta and in Saskatchewan and on Ordovician to Silurian 1 formations in western Alberta Saskatchewan and southwestern Manitoba 2 In the Northwest Territories some of its uppermost units are exposed at surface or are unconformably overlain by Cretaceous strata 1 The Lower Elk Point Group is equivalent to the Stone Formation and its equivalents and the Headless and Nahanni Formations in northerneastern British Columbia and the southwestern Northwest Territories In the same areas the Upper Elk Point includes the Pine Point Group and is equivalent to parts of the Horn River Formation Besa River Formation and others 2 Petroleum and Natural Gas editThe porous carbonate rocks of the Elk Point Group host major petroleum and natural gas reservoirs As of 1994 the Initial Established Recoverable Petroleum Reserves and the Cumulative Petroleum Production for the group were estimated at 339 3 and 240 4 million cubic metres respectively For natural gas the Initial Established Marketable Reserves and the Cumulative Production were estimated at 142 7 and 79 5 billion cubic metres respectively 5 References edit a b c d e f g h Meijer Drees N C 1986 Evaporitic deposits of western Canada Geological Survey of Canada paper 85 20 a b c d e f g h i j k l m n o p q r s t u v w x y Glass D J editor 1997 Lexicon of Canadian Stratigraphy vol 4 Western Canada including eastern British Columbia Alberta Saskatchewan and southern Manitoba Canadian Society of Petroleum Geologists Calgary 1423 p on CD ROM ISBN 0 920230 23 7 a b McGehee J R 1949 Pre Waterways Paleozoic stratigraphy of Alberta Plains Bull American Association of Petroleum Geologists 33 4 p 603 613 a b 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 Retrieved 2016 06 20 a href Template Cite web html title Template Cite web cite web a CS1 maint multiple names authors list link a b c Mossop G D and Shetsen I compilers Canadian Society of Petroleum Geologists 1994 The Geological Atlas of the Western Canada Sedimentary Basin Chapter 32 Oil and Gas Resources of the Western Canada Sedimentary Basin Retrieved 2016 06 20 a href Template Cite web html title Template Cite web cite web a CS1 maint multiple names authors list link Schneider C L Grobe F J Hein 2018 01 24 2012 ERCB AGS Open File Report 2012 20 Outcrops of the La Loche Contact Rapids and Keg River Formations Devonian on the Clearwater River Alberta NTS 74D 9 and Saskatchewan NTS 74C 12 PDF Energy Resources Conservation Board Alberta Geological Survey Her Majesty the Queen in Right of Alberta 2013 ISBN 978 1 4601 0089 9 Retrieved 2018 01 24 Retrieved from https en wikipedia org w index php title Elk Point Group amp oldid 1190501466 Subdivisions, wikipedia, wiki, book, books, library,
