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Canadian Shield

January 13, 2023

The Canadian Shield (French: Bouclier canadien [buklje kanadjɛ̃]), also called the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton (or Laurentia), the ancient geologic core of the North American continent. Glaciation has left the area with only a thin layer of soil, through which exposures of igneous bedrock resulting from its long volcanic history are frequently visible.[3] As a deep, common, joined bedrock region in eastern and central Canada, the Shield stretches north from the Great Lakes to the Arctic Ocean, covering over half of Canada and most of Greenland; it also extends south into the northern reaches of the United States.

Canadian Shield
Stratigraphic range:
Precambrian
TypeShield
Unit ofNorth American craton
Sub-unitsLaurentian Upland
Kazan[1]
Area8,000,000 km2[2]
Location
Coordinates52°00′N 71°00′W / 52.000°N 71.000°W / 52.000; -71.000Coordinates: 52°00′N 71°00′W / 52.000°N 71.000°W / 52.000; -71.000
RegionNorth America
CountryCanada
United States
Greenland

The Canadian Shield is a broad region of Precambrian rock (pictured in shades of red) that encircles Hudson Bay. It spans eastern, northeastern, and east-central Canada and the upper midwestern United States.

Geographical extent

The Canadian Shield is a physiographic division comprising four smaller physiographic provinces: the Laurentian Upland, Kazan Region, Davis and James.[1] The shield extends into the United States as the Adirondack Mountains (connected by the Frontenac Axis) and the Superior Upland. The Canadian Shield is a U-shaped subsection of the Laurentia craton signifying the area of greatest glacial impact (scraping down to bare rock) creating the thin soils. The age of the Canadian Shield is estimated to be 4.28 Ga. The Canadian Shield once had jagged peaks, higher than any of today's mountains, but millions of years of erosion have changed these mountains to rolling hills.[4]

The Canadian Shield is a collage of Archean plates and accreted juvenile arc terranes and sedimentary basins of the Proterozoic Eon that were progressively amalgamated during the interval 2.45–1.24 Ga, with the most substantial growth period occurring during the Trans-Hudson orogeny, between c. 1.90–1.80 Ga.[5] The Canadian Shield was the first part of North America to be permanently elevated above sea level and has remained almost wholly untouched by successive encroachments of the sea upon the continent. It is the Earth's greatest area of exposed Archean rock. The metamorphic base rocks are mostly from the Precambrian (between 4.5 billion and 540 million years ago) and have been repeatedly uplifted and eroded. Today it consists largely of an area of low relief 300–610 m (980–2,000 ft) above sea level with a few monadnocks and low mountain ranges (including the Laurentian Mountains) probably eroded from the plateau during the Cenozoic Era. During the Pleistocene Epoch, continental ice sheets depressed the land surface (creating Hudson Bay) but also tilted up its northeastern "rim" (the Torngat), scooped out thousands of lake basins, and carried away much of the region's soil. The northeastern portion, however, became tilted up so that, in northern Labrador and Baffin Island, the land rises to more than 1,500 metres (5,000 feet) above sea level.

When the Greenland section is included, the Canadian Shield is approximately circular, bounded on the northeast by the northeast edge of Greenland, with Hudson Bay in the middle. It covers much of Greenland, all of Labrador and the Great Northern Peninsula of Newfoundland, most of Quebec north of the St. Lawrence River, much of Ontario including northern sections of the Ontario Peninsula, the Adirondack Mountains[6] of New York, the northernmost part of Lower Michigan and all of Upper Michigan, northern Wisconsin, northeastern Minnesota, the central and northern portions of Manitoba away from Hudson Bay, northern Saskatchewan, a small portion of northeastern Alberta,[7] mainland Northwest Territories to the east of a line extended north from the Saskatchewan-Alberta border, most of Nunavut's mainland and, of its Arctic Archipelago, Baffin Island and significant bands through Somerset, Southampton, Devon and Ellesmere islands.[2] In total, the exposed area of the Shield covers approximately 8,000,000 km2 (3,100,000 sq mi). The true extent of the Shield is greater still and stretches from the Western Cordillera in the west to the Appalachians in the east and as far south as Texas, but these regions are overlaid with much younger rocks and sediment.

 
Panorama of Canadian Shield geography in the Flin Flon, Manitoba, region. Big Island Lake is in the background.

Geology

The Canadian Shield is among the oldest on Earth, with regions dating from 2.5 to 4.2 billion years.[8] The multitude of rivers and lakes in the region is classical example of a deranged drainage system, caused by the watersheds of the area being disturbed by glaciation and the effect of post-glacial rebound.[9] The Shield was originally an area of very large, very tall mountains (about 12,000 m or 39,000 ft)[10] with much volcanic activity, but the area was eroded to nearly its current topographic appearance of relatively low relief over 500 million years ago.[11][12] Erosion has exposed the roots of the mountains, which take the form of greenstone belts in which belts of volcanic rock that have been altered by metamorphism are surrounded by granitic rock. These belts range in age from 3600 to 2680 million years old.[13] Much of the granitic rock belongs to the distinctive tonalite–trondhjemite–granodiorite family of rocks, which are characteristic of Archean continental crust.[14] Many of Canada's major ore deposits are associated with greenstone belts.[15]

The Sturgeon Lake Caldera in Kenora District, Ontario, is one of the world's best preserved mineralized Neoarchean caldera complexes, which is 2.7 billion years old.[16] The Canadian Shield also contains the Mackenzie dike swarm, which is the largest dike swarm known on Earth.[17]

Mountains have deep roots and float on the denser mantle much like an iceberg at sea. As mountains erode, their roots rise and are eroded in turn. The rocks that now form the surface of the Shield were once far below the Earth's surface.

The high pressures and temperatures at those depths provided ideal conditions for mineralization. Although these mountains are now heavily eroded, many large mountains still exist in Canada's far north called the Arctic Cordillera. This is a vast, deeply dissected mountain range, stretching from northernmost Ellesmere Island to the northernmost tip of Labrador. The range's highest peak is Nunavut's Barbeau Peak at 2,616 metres (8,583 ft) above sea level.[18] Precambrian rock is the major component of the bedrock.

The North American craton is the bedrock forming the heart of the North American continent and the Canadian Shield is the largest exposed part of the craton's bedrock.

The Canadian Shield is part of an ancient continent called Arctica, which was formed about 2.5 billion years ago during the Neoarchean era. It[clarification needed] was split[when?] into Greenland, Laurentia, Scotland, and Siberia, and is now roughly situated in the Arctic around the current North Pole.

Ecology

 
Typical shield landscape in a southern Ontario region with very few old growth trees, due to a history of logging and fires. Black River, Queen Elizabeth II Wildlands Provincial Park.

The current surface expression of the Shield is one of very thin soil lying on top of the bedrock, with many bare outcrops. This arrangement was caused by severe glaciation during the ice age, which covered the Shield and scraped the rock clean.

The lowlands of the Canadian Shield have a very dense soil that is not suitable for forestation; it also contains many marshes and bogs (muskegs). The rest of the region has coarse soil that does not retain moisture well and is frozen with permafrost throughout the year. Forests are not as dense in the north.

The Shield is covered in parts by vast boreal forests in the south that support natural ecosystems as well as a major logging industry. The boreal forest area gives way to the Eastern Canadian Shield taiga that covers northern Quebec and most of Labrador. The Midwestern Canadian Shield forests that run westwards from Northwestern Ontario have boreal forests that give way to taiga in the most northerly parts of Manitoba and Saskatchewan. Hydrologic drainage is generally poor, the soil compacting effects of glaciation being one of the many causes. Tundra typically prevails in the northern regions. Many mammals such as caribou, white-tailed deer, moose, wolves, wolverines, weasels, mink, otters, grizzly bear, polar bears and black bears are present.[19] In the case of polar bears (Ursus maritimus), the Shield area contains many of their denning locations, such as the Wapusk National Park.[20]

Mining and economics

The Canadian Shield is one of the world's richest areas in terms of mineral ores. It is filled with substantial deposits of nickel, gold, silver, and copper. Throughout the Shield there are many mining towns extracting these minerals. The largest, and one of the best known, is Sudbury, Ontario. Sudbury is an exception to the normal process of forming minerals in the Shield since the Sudbury Basin is an ancient meteorite impact crater. Ejecta from the meteorite impact was found in the Rove Formation in May 2007. The nearby but less-known Temagami Magnetic Anomaly has striking similarities to the Sudbury Basin. This suggests it could be a second metal-rich impact crater.[21]

In northeastern Quebec, the giant Manicouagan Reservoir is the site of an extensive hydroelectric project (Manic-cinq, or Manic-5). This is one of the largest-known meteorite impact craters on Earth, though not as large as the Sudbury crater; it is currently ranked 5th, while Sudbury is 3rd.

The Flin Flon greenstone belt in central Manitoba and east-central Saskatchewan "is one of the largest Paleoproterozoic volcanic-hosted massive sulfide (VMS) districts in the world, containing 27 copper-zinc-(gold) deposits from which more than 183 million tonnes of sulfide have been mined."[22]

The Canadian Shield, particularly the portion in the Northwest Territories, has recently been the site of several major diamond discoveries. The kimberlite pipes in which the diamonds are found are closely associated with cratons, which provide the deep lithospheric mantle required to stabilize diamond as a mineral. The kimberlite eruptions then bring the diamonds from over 150 kilometres (93 mi) depth to the surface. The Ekati and Diavik mines are actively mining kimberlite diamonds.

See also

References

  1. ^ a b The Atlas of Canada (12 September 2016). "Physiographic Regions Map". Natural Resources Canada. Retrieved 2019-11-15.
  2. ^ a b "Canadian Shield". Encyclopædia Britannica. from the original on 2015-06-24. Retrieved 2009-02-10.
  3. ^ Marshak, Stephen (2009). Essentials of geology (3rd ed.). New York: W.W. Norton. ISBN 978-0393932386.
  4. ^ James-Abra, Erin. "Canadian Shield". Canadian Encyclopedia. from the original on 11 January 2018. Retrieved 24 January 2018.
  5. ^ Corrigan, D. (2008). (PDF). Archived from the original (PDF) on April 9, 2008. Retrieved 2008-03-05.
  6. ^ Peterson Field Guide to Geology of Eastern North America by Roberts, David & Roger Tory Peterson.
  7. ^ Alberta Heritage - Alberta Online Encyclopedia Archived 2010-12-08 at Archive-It - The Canadian Shield Region of Alberta
  8. ^ Tsuyoshi Iizuka, at al., "Geology and Zircon Geochronology of the Acasta Gneiss Complex", Precambrian Research, 153 (2007) pp. 179–208
  9. ^ Pidwirny, M. (2006). "The Drainage Basin Concept". Fundamentals of Physical Geography (2nd ed.).
  10. ^ Clark, Bruce W. (1999). "Geologic History". Making Connections: Canada's geography. Scarborough, Ontario: Prentice Hall Ginn Canada. pp. 95. ISBN 978-0-13-012635-1.
  11. ^ Ambrose, J. W. (1 September 1964). "Exhumed paleoplains of the Precambrian Shield of North America". American Journal of Science. 262 (7): 817–857. Bibcode:1964AmJS..262..817A. doi:10.2475/ajs.262.7.817.
  12. ^ Shilts, William W.; Aylsworth, Janice M.; Kaszycki, Christine A.; Klassen, Rodney A. (1987). "Canadian Shield". Geomorphic Systems of North America: 119–161. doi:10.1130/DNAG-CENT-v2.119. ISBN 0813753023.
  13. ^ Card, K.D. (August 1990). "A review of the Superior Province of the Canadian Shield, a product of Archean accretion". Precambrian Research. 48 (1–2): 99–156. Bibcode:1990PreR...48...99C. doi:10.1016/0301-9268(90)90059-Y.
  14. ^ Smithies, R.H (15 October 2000). "The Archaean tonalite–trondhjemite–granodiorite (TTG) series is not an analogue of Cenozoic adakite". Earth and Planetary Science Letters. 182 (1): 115–125. Bibcode:2000E&PSL.182..115S. doi:10.1016/S0012-821X(00)00236-3.
  15. ^ de Geoffroy, J.; Wignall, T. K. (1 May 1971). "A probabilistic appraisal of mineral resources in a portion of the Grenville Province of the Canadian shield". Economic Geology. 66 (3): 466–479. doi:10.2113/gsecongeo.66.3.466.
  16. ^ Caldera Volcanoes 2012-08-14 at the Wayback Machine Retrieved on 2007-07-20
  17. ^ Pilkington, Mark; Roest, Walter R. (1998). "Removing varying directional trends in aeromagnetic data". Geophysics. 63 (2): 446–453. Bibcode:1998Geop...63..446P. doi:10.1190/1.1444345.
  18. ^ "Barbeau Peak". Bivouac.com.
  19. ^ World Wildlife Fund, ed. (2001). . WildWorld Ecoregion Profile. National Geographic Society. Archived from the original on 2010-03-08.
  20. ^ C. Michael Hogan (2008) Polar Bear: Ursus maritimus, Globaltwitcher.com, ed. Nicklas Stromberg December 24, 2008, at the Wayback Machine
  21. ^ 3-D Magnetic Imaging using Conjugate Gradients: Temagami anomaly 2009-07-11 at the Wayback Machine Retrieved on 2008-03-12
  22. ^ Troymet Exploration, , by Jessica Norris & Tracy Hurley (Whitehorse, Yukon: Aurora Geosciences, 2007‑09‑24).

Further reading

  • Schwartzenberger, Tina (2005), The Canadian Shield, Weigl Educational, ISBN 1-55388-141-9

January 13, 2023
canadian, shield, french, bouclier, canadien, buklje, kanadjɛ, also, called, laurentian, plateau, geologic, shield, large, area, exposed, precambrian, igneous, high, grade, metamorphic, rocks, forms, north, american, craton, laurentia, ancient, geologic, core,. The Canadian Shield French Bouclier canadien buklje kanadjɛ also called the Laurentian Plateau is a geologic shield a large area of exposed Precambrian igneous and high grade metamorphic rocks It forms the North American Craton or Laurentia the ancient geologic core of the North American continent Glaciation has left the area with only a thin layer of soil through which exposures of igneous bedrock resulting from its long volcanic history are frequently visible 3 As a deep common joined bedrock region in eastern and central Canada the Shield stretches north from the Great Lakes to the Arctic Ocean covering over half of Canada and most of Greenland it also extends south into the northern reaches of the United States Canadian ShieldStratigraphic range Precambrian Pha Proterozoic Archean Had nTypeShieldUnit ofNorth American cratonSub unitsLaurentian UplandKazan 1 Area8 000 000 km2 2 LocationCoordinates52 00 N 71 00 W 52 000 N 71 000 W 52 000 71 000 Coordinates 52 00 N 71 00 W 52 000 N 71 000 W 52 000 71 000RegionNorth AmericaCountryCanadaUnited StatesGreenlandThe Canadian Shield is a broad region of Precambrian rock pictured in shades of red that encircles Hudson Bay It spans eastern northeastern and east central Canada and the upper midwestern United States Contents 1 Geographical extent 2 Geology 3 Ecology 4 Mining and economics 5 See also 6 References 7 Further readingGeographical extent EditThe Canadian Shield is a physiographic division comprising four smaller physiographic provinces the Laurentian Upland Kazan Region Davis and James 1 The shield extends into the United States as the Adirondack Mountains connected by the Frontenac Axis and the Superior Upland The Canadian Shield is a U shaped subsection of the Laurentia craton signifying the area of greatest glacial impact scraping down to bare rock creating the thin soils The age of the Canadian Shield is estimated to be 4 28 Ga The Canadian Shield once had jagged peaks higher than any of today s mountains but millions of years of erosion have changed these mountains to rolling hills 4 The Canadian Shield is a collage of Archean plates and accreted juvenile arc terranes and sedimentary basins of the Proterozoic Eon that were progressively amalgamated during the interval 2 45 1 24 Ga with the most substantial growth period occurring during the Trans Hudson orogeny between c 1 90 1 80 Ga 5 The Canadian Shield was the first part of North America to be permanently elevated above sea level and has remained almost wholly untouched by successive encroachments of the sea upon the continent It is the Earth s greatest area of exposed Archean rock The metamorphic base rocks are mostly from the Precambrian between 4 5 billion and 540 million years ago and have been repeatedly uplifted and eroded Today it consists largely of an area of low relief 300 610 m 980 2 000 ft above sea level with a few monadnocks and low mountain ranges including the Laurentian Mountains probably eroded from the plateau during the Cenozoic Era During the Pleistocene Epoch continental ice sheets depressed the land surface creating Hudson Bay but also tilted up its northeastern rim the Torngat scooped out thousands of lake basins and carried away much of the region s soil The northeastern portion however became tilted up so that in northern Labrador and Baffin Island the land rises to more than 1 500 metres 5 000 feet above sea level When the Greenland section is included the Canadian Shield is approximately circular bounded on the northeast by the northeast edge of Greenland with Hudson Bay in the middle It covers much of Greenland all of Labrador and the Great Northern Peninsula of Newfoundland most of Quebec north of the St Lawrence River much of Ontario including northern sections of the Ontario Peninsula the Adirondack Mountains 6 of New York the northernmost part of Lower Michigan and all of Upper Michigan northern Wisconsin northeastern Minnesota the central and northern portions of Manitoba away from Hudson Bay northern Saskatchewan a small portion of northeastern Alberta 7 mainland Northwest Territories to the east of a line extended north from the Saskatchewan Alberta border most of Nunavut s mainland and of its Arctic Archipelago Baffin Island and significant bands through Somerset Southampton Devon and Ellesmere islands 2 In total the exposed area of the Shield covers approximately 8 000 000 km2 3 100 000 sq mi The true extent of the Shield is greater still and stretches from the Western Cordillera in the west to the Appalachians in the east and as far south as Texas but these regions are overlaid with much younger rocks and sediment Panorama of Canadian Shield geography in the Flin Flon Manitoba region Big Island Lake is in the background Geology EditThe Canadian Shield is among the oldest on Earth with regions dating from 2 5 to 4 2 billion years 8 The multitude of rivers and lakes in the region is classical example of a deranged drainage system caused by the watersheds of the area being disturbed by glaciation and the effect of post glacial rebound 9 The Shield was originally an area of very large very tall mountains about 12 000 m or 39 000 ft 10 with much volcanic activity but the area was eroded to nearly its current topographic appearance of relatively low relief over 500 million years ago 11 12 Erosion has exposed the roots of the mountains which take the form of greenstone belts in which belts of volcanic rock that have been altered by metamorphism are surrounded by granitic rock These belts range in age from 3600 to 2680 million years old 13 Much of the granitic rock belongs to the distinctive tonalite trondhjemite granodiorite family of rocks which are characteristic of Archean continental crust 14 Many of Canada s major ore deposits are associated with greenstone belts 15 The Sturgeon Lake Caldera in Kenora District Ontario is one of the world s best preserved mineralized Neoarchean caldera complexes which is 2 7 billion years old 16 The Canadian Shield also contains the Mackenzie dike swarm which is the largest dike swarm known on Earth 17 Mountains have deep roots and float on the denser mantle much like an iceberg at sea As mountains erode their roots rise and are eroded in turn The rocks that now form the surface of the Shield were once far below the Earth s surface The high pressures and temperatures at those depths provided ideal conditions for mineralization Although these mountains are now heavily eroded many large mountains still exist in Canada s far north called the Arctic Cordillera This is a vast deeply dissected mountain range stretching from northernmost Ellesmere Island to the northernmost tip of Labrador The range s highest peak is Nunavut s Barbeau Peak at 2 616 metres 8 583 ft above sea level 18 Precambrian rock is the major component of the bedrock The North American craton is the bedrock forming the heart of the North American continent and the Canadian Shield is the largest exposed part of the craton s bedrock The Canadian Shield is part of an ancient continent called Arctica which was formed about 2 5 billion years ago during the Neoarchean era It clarification needed was split when into Greenland Laurentia Scotland and Siberia and is now roughly situated in the Arctic around the current North Pole Weathered Precambrian pillow lava in the Temagami Greenstone Belt Folded Precambrian gneiss of the Canadian Shield in Georgian Bay Ontario Typical Canadian Shield landscape spruce lakes bogs and rockEcology Edit Typical shield landscape in a southern Ontario region with very few old growth trees due to a history of logging and fires Black River Queen Elizabeth II Wildlands Provincial Park The current surface expression of the Shield is one of very thin soil lying on top of the bedrock with many bare outcrops This arrangement was caused by severe glaciation during the ice age which covered the Shield and scraped the rock clean The lowlands of the Canadian Shield have a very dense soil that is not suitable for forestation it also contains many marshes and bogs muskegs The rest of the region has coarse soil that does not retain moisture well and is frozen with permafrost throughout the year Forests are not as dense in the north The Shield is covered in parts by vast boreal forests in the south that support natural ecosystems as well as a major logging industry The boreal forest area gives way to the Eastern Canadian Shield taiga that covers northern Quebec and most of Labrador The Midwestern Canadian Shield forests that run westwards from Northwestern Ontario have boreal forests that give way to taiga in the most northerly parts of Manitoba and Saskatchewan Hydrologic drainage is generally poor the soil compacting effects of glaciation being one of the many causes Tundra typically prevails in the northern regions Many mammals such as caribou white tailed deer moose wolves wolverines weasels mink otters grizzly bear polar bears and black bears are present 19 In the case of polar bears Ursus maritimus the Shield area contains many of their denning locations such as the Wapusk National Park 20 Mining and economics EditThe Canadian Shield is one of the world s richest areas in terms of mineral ores It is filled with substantial deposits of nickel gold silver and copper Throughout the Shield there are many mining towns extracting these minerals The largest and one of the best known is Sudbury Ontario Sudbury is an exception to the normal process of forming minerals in the Shield since the Sudbury Basin is an ancient meteorite impact crater Ejecta from the meteorite impact was found in the Rove Formation in May 2007 The nearby but less known Temagami Magnetic Anomaly has striking similarities to the Sudbury Basin This suggests it could be a second metal rich impact crater 21 In northeastern Quebec the giant Manicouagan Reservoir is the site of an extensive hydroelectric project Manic cinq or Manic 5 This is one of the largest known meteorite impact craters on Earth though not as large as the Sudbury crater it is currently ranked 5th while Sudbury is 3rd The Flin Flon greenstone belt in central Manitoba and east central Saskatchewan is one of the largest Paleoproterozoic volcanic hosted massive sulfide VMS districts in the world containing 27 copper zinc gold deposits from which more than 183 million tonnes of sulfide have been mined 22 The Canadian Shield particularly the portion in the Northwest Territories has recently been the site of several major diamond discoveries The kimberlite pipes in which the diamonds are found are closely associated with cratons which provide the deep lithospheric mantle required to stabilize diamond as a mineral The kimberlite eruptions then bring the diamonds from over 150 kilometres 93 mi depth to the surface The Ekati and Diavik mines are actively mining kimberlite diamonds See also Edit Geography portal Canada portalBaltic Shield Athabasca Basin Geology of Ontario Platform geology Oldest rock Basement geology Volcanology of Canada Wisconsin Glaciation Glacial history of MinnesotaReferences Edit a b The Atlas of Canada 12 September 2016 Physiographic Regions Map Natural Resources Canada Retrieved 2019 11 15 a b Canadian Shield Encyclopaedia Britannica Archived from the original on 2015 06 24 Retrieved 2009 02 10 Marshak Stephen 2009 Essentials of geology 3rd ed New York W W Norton ISBN 978 0393932386 James Abra Erin Canadian Shield Canadian Encyclopedia Archived from the original on 11 January 2018 Retrieved 24 January 2018 Corrigan D 2008 Metallogeny and Tectonic Evolution of the Trans Hudson Orogen PDF Archived from the original PDF on April 9 2008 Retrieved 2008 03 05 Peterson Field Guide to Geology of Eastern North America by Roberts David amp Roger Tory Peterson Alberta Heritage Alberta Online Encyclopedia Archived 2010 12 08 at Archive It The Canadian Shield Region of Alberta Tsuyoshi Iizuka at al Geology and Zircon Geochronology of the Acasta Gneiss Complex Precambrian Research 153 2007 pp 179 208 Pidwirny M 2006 The Drainage Basin Concept Fundamentals of Physical Geography 2nd ed Clark Bruce W 1999 Geologic History Making Connections Canada s geography Scarborough Ontario Prentice Hall Ginn Canada pp 95 ISBN 978 0 13 012635 1 Ambrose J W 1 September 1964 Exhumed paleoplains of the Precambrian Shield of North America American Journal of Science 262 7 817 857 Bibcode 1964AmJS 262 817A doi 10 2475 ajs 262 7 817 Shilts William W Aylsworth Janice M Kaszycki Christine A Klassen Rodney A 1987 Canadian Shield Geomorphic Systems of North America 119 161 doi 10 1130 DNAG CENT v2 119 ISBN 0813753023 Card K D August 1990 A review of the Superior Province of the Canadian Shield a product of Archean accretion Precambrian Research 48 1 2 99 156 Bibcode 1990PreR 48 99C doi 10 1016 0301 9268 90 90059 Y Smithies R H 15 October 2000 The Archaean tonalite trondhjemite granodiorite TTG series is not an analogue of Cenozoic adakite Earth and Planetary Science Letters 182 1 115 125 Bibcode 2000E amp PSL 182 115S doi 10 1016 S0012 821X 00 00236 3 de Geoffroy J Wignall T K 1 May 1971 A probabilistic appraisal of mineral resources in a portion of the Grenville Province of the Canadian shield Economic Geology 66 3 466 479 doi 10 2113 gsecongeo 66 3 466 Caldera Volcanoes Archived 2012 08 14 at the Wayback Machine Retrieved on 2007 07 20 Pilkington Mark Roest Walter R 1998 Removing varying directional trends in aeromagnetic data Geophysics 63 2 446 453 Bibcode 1998Geop 63 446P doi 10 1190 1 1444345 Barbeau Peak Bivouac com World Wildlife Fund ed 2001 Northern Canadian Shield taiga WildWorld Ecoregion Profile National Geographic Society Archived from the original on 2010 03 08 C Michael Hogan 2008 Polar Bear Ursus maritimus Globaltwitcher com ed Nicklas Stromberg Archived December 24 2008 at the Wayback Machine 3 D Magnetic Imaging using Conjugate Gradients Temagami anomaly Archived 2009 07 11 at the Wayback Machine Retrieved on 2008 03 12 Troymet Exploration Report on the 2007 Diamond Drilling Program McClarty Lake Project Manitoba The Pas Mining District NTS 63 K 08 UTM ZONE 14 N 415938 E 6038968 N 54 29 28 N 100 17 52 W by Jessica Norris amp Tracy Hurley Whitehorse Yukon Aurora Geosciences 2007 09 24 Further reading EditSchwartzenberger Tina 2005 The Canadian Shield Weigl Educational ISBN 1 55388 141 9 Retrieved from https en wikipedia org w index php title Canadian Shield amp oldid 1131290757, wikipedia, wiki, book, books, library,

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