- Volcanism in Canada
Canadahas examples of almost every type of volcanofound on earth, including stratovolcanoes, calderas, cinder cones, shield volcanoes, maars, submarine volcanoes and tuyas. Most of Canada's volcanoes are located in British Columbia. Several mountains that many British Columbians look at every day are dormant volcanoes. Most of them have erupted during the Pleistoceneor Holoceneepochs, and others have the potential to erupt in the near future.
Volcanism in Canada has been responsible for many of Canada's geographical features and mineralization. While the land's volcanic activity dates back to the
Precambrianera, activity continues today with eruptions occurring in Western Canadaapproximately every few hundred years. Because many of Canada's volcanoes are in remote, rugged areas and the level of activity is low, Canada is commonly thought to occupy a gap in the Pacific Ring of Firebetween the Cascade Volcanic Arc of the western United Statesand the Aleutian volcanoes of Alaska, yet British Columbia and Yukoninclude more than 100 separate volcanic centers that have been active during the Quaternary.
Volcanism in Western Canada
Western Canadalies in an area of active tectonics and volcanism, but the scattered population has witnessed few eruptions owing to the remoteness of the volcanoes and their low level of activity. There are over 200 potentially active volcanic centers that stretch northward from the Cascade Range, 49 of which have erupted in the past 10,000 years [ [http://www.springerlink.com/content/q5p6lq507879p481/ The Vulnerability of Canada to Volcanic Hazards] Retrieved on 2007-07-27] and many of which have been active in the past two million years.
Ten to fifteen million years ago, floods of basaltic lava erupted on a gently undulating topography with relief of about 7 000 m (2,000 ft) and built up flat-lying
plateaus in central British Columbia and Yukon Territory covering more than 39 000 km² (1500 sq mi).
shield volcanoes developed during the Tertiaryperiod in north-central British Columbia and some were active intermittently to recent times. Mount Edzizaand Level Mountainare most spectacular examples. Mount Edziza is a stratovolcanoconsisting of a basal shield of basaltic flows surmounted by a central vent and flanked by numerous satellite cones, ash beds and blocky lavas. The complex has a long history of volcanic eruption that began about 10 million years ago and ended about 1300 years ago. The volcanoes are grouped into several volcanic fields and volcanic belts:
Garibaldi Volcanic Beltis a north-south range of volcanoes in southwestern British Columbia. It is the northern extension of the Cascade Volcanic Arc in the northwestern United States(including Mount Rainierand Mount St. Helens), and contains the most explosive young volcanoes in Canada. It was formed by subductionof the Juan de Fuca Plateat the Cascadia subduction zone. Eruption styles within the belt range from effusive to explosive, with compositions from basaltto rhyolite. A major catastrophic eruption occurred in the Garibaldi Volcanic Belt about 2,350 years ago at a volcanic complex called Mount Meager. The eruption sent an ash column at least 20 km high into the stratosphereand dammed the Lillooet Riverwith breccia. The Garibaldi Volcanic Belt contains two further volcanic fields, the Franklin Glacier Volcanoand Mount Silverthrone, which lie 140 and 190 kilometres northwest of the main volcanic belt. These volcanoes are originally part of the eroded Miocene Pemberton Volcanic Belt.
Anahim Volcanic Beltis an east-west line of volcanoes stretching from just north of Vancouver Islandto near Quesnel, British Columbia. These volcanoes probably formed when the North American Platemoved over a hotspot, similar to the one feeding the Hawaiian Islandscalled the Anahim hotspot. It contains three major shield volcanoes called the Rainbow Range, Ilgachuz Rangeand Itcha Range. The last volcanic eruption within the belt was about 7000 years ago at a small tree-covered cinder conecalled Nazko Cone. The volcano's oldest eruption is approximately 340,000 years old.
Northern Cordilleran Volcanic Province(also called the Stikine Volcanic Belt) is the most active volcanic region in Canada, containing more than 100 potentially active volcanoes. Several eruptions are known to have occurred within this region in the past 400 years and it contains Canada's largest volcanoes. It formed as a result of faulting, cracking, rifting and the interaction between the Pacific Plateand the North American Plate. The Fort Selkirk Volcanic Fieldis Canada's northernmost Holocene volcanic field. The youngest cone, Volcano Mountain, produced young nephelinitic lava flows that remain unvegetated and appear to be only a few hundred years old. However, dating of sediments in a lake impounded by the lava flows indicated that the youngest flows could not be younger than mid-Holocene and could be early Holoceneor older.
Chilcotin Plateau Basaltsin southern British Columbia is an area of small lava flows about 150 kilometers ofrom the Pacific Ocean. It is thought to have formed as a result of back-arc extension behind the Cascadia subduction zone. Most of the volcanoes erupted while the Garibaldi Volcanic Belt was just forming. However, there have been smaller eruptions, during the Pleistoceneperiod.
Wells Gray-Clearwater Volcanic Fieldin southeastern British Columbia consists of numerous small, basaltic volcanoes and extensive lavaflows. The origin of the volcanism is yet unknown but is probably related to crust thinning. Many individual volcanoes have been active for the last 3 million years. Some of the lava flows are similar to those that erupted at Volcano Mountainin the Yukon, which is called olivine nephelinite. Canada's only maar-like volcano is found in the Wells Gray-Clearwater Volcanic Field. [ [http://gsc.nrcan.gc.ca/volcanoes/type_e.php Volcanoes of Canada - Types of volcanoes] ]
Wrangell Volcanic Fieldlies mostly in Alaska, but extends into southeastern Yukon. It was formed by subductionof the Pacific Platebeneath the North American Plateat the easternmost end of the Aleutian Trench. The Canadian portion is dominated by Tertiary lavas with minor alkaline and calc-alkaline lavas that overlie a leaky transform fault.
basaltic to rhyolitic volcanoes and hypabyssal rocks of the Alert Bay Volcanic Beltin northern Vancouver Islandare probably linked with the subducted margin flanked by the Explorer and Juan de Fuca plates at the Cascadia subduction zone. It appears to have been active during the Plioceneand Pleistocenetime. However, no Holoceneeruptions are known, and volcanic activity in the belt has likely ceased.
Monitoring Canadian volcanoes
Volcano monitoringin Canada is a lower priority than other hazards, such as earthquakes, tsunamis and landslides. Most of Canada's volcanoes are in remote locations, although some volcanoes pose a significant threat to local population. However, as for earthquakemonitoring, future eruptions in Canada are expected and could have a large effect on people that live in the region. Over the past 50 years, the Geological Survey of Canadahas known past activity at Canada's volcanoes. However, there is still not enough knowledge about the occurrence of their eruptions to expect which volcanoes will possibly erupt next and what their effects will be. Volcano monitoring in Canada is continuing, but none of the volcanoes is being satisfactorily monitored to let scientists verify how active their magma chambers and systems are. If a Canadian volcano turns highly tense, the seismic monitoring system will possibly sense the growing of movement at the volcanoes.
Recent volcanic activity
Many Canadian volcanoes continue to be geologically active. The most geologically recent volcanic eruptions include:
Level Mountain Range, Canada's most voluminous and most persistent eruptive center, might have erupted sometime during the Holocene.
Nazko Cone, the youngest volcano in the Anahim Volcanic Belt, erupted 7200 BP.
Hoodoo Mountainerupted 7050 BP.
Mount Meagererupted about 2350 BP, sending an ash column approximately Unit km|20|0 high into the stratosphere.
Mount Edziza, Canada's second largest eruptive center, erupted about 1340 BP.
Mount Silverthrone, might have eruptions younger than 1000.
* Possible eruptions in the
Wells Gray-Clearwater Volcanic Fieldin 1500.
Tseax River Coneerupted in 1775.
Ruby Mountainmight have erupted in 1898.
Lava Fork Valleymight have erupted in 1904. Western Canadais also seismically active. 11 volcanoes in Canada appear related to seismic activity since 1975, including: Mount Silverthrone, Mount Meager, Wells Gray-Clearwater Volcanic Field, Mount Garibaldi, Mount Cayley, Castle Rock, Lava Fork Valley, Mount Edziza, Hoodoo Mountainand Crow Lagoon. [ [http://www.bcminerals.ca/pdf/CanadianVolcanoes-CH2005.pdf Volcanoes of Canada] Retrieved on 2007-09-19] This suggests that these volcanoes still contain living magmaplumbing systems. Although the existing data do not allow a clear conclusion, these observations are further indications that some of Canada's volcanoes are potentially active, and that their associated hazards may be significant. It is noteworthy that the seismic activity correlates with some of Canada's most youthful volcanoes, and with long-lived volcanic centers with a history of significant explosive behavior, such as Mount Garibaldi, Mount Cayley, Mount Meagerand Mount Edziza.
The 1775 eruption of the
Tseax River Coneis Canada's worst known geophysical disaster. The eruption produced a 22.5 km long lava flow, destroying two Nisga'a villages and resulted in the death of approximately 2000 Nisga'a people by poisonous smoke and gases. The lava flows traveled south 5 km where they crossed the border into Alaskaand dammed the Blue River. The Nass Rivervalley was inundated by the lava flows and contain abundant tree molds and lava tubes. The event happened at the same time with the arrival of the first European explorers to penetrate the uncharted coastal waters of northern British Columbia. Today, the basaltic lava deposits are a draw to tourists and are part of the Nisga'a Memorial Lava Beds Provincial Park.
A series of <3.0 Magnitude earthquakes began October 9th, 2007 in the vicinity of
Nazko Conewhich could signal the resumption of intense subterraenean volcanic activity in the area. 34 such <3.0 Magnitude earthquakes were observed on October 10th, 2007 alone. Since then more than 1000 small earthquakes have been recorded. [ [http://americasvolcanoes.info/category/volcanoes-of-the-world/nazko-cone/ America's Volcanoes: Nazko Cone] Retrieved on 2007-11-17] These earthquakes are thought to have originated 25 kilometers below the surface, but none of these earthquakes have been felt by people. The cause of this seismic activity is believed to be the upwelling of 500,000 m2 [http://www.geog.ubc.ca/courses/geog376/students/class07/volcanic/index.html Effusive Volcanism Near Quesnel] Retrieved on 2008-01-06] of magmabecause the area is not close to any faults or tectonic plate boundaries. [ [http://earthquakescanada.nrcan.gc.ca/nazko/nazko_summary_e.php Natural Resources Canada: Nazko Cone] Retrieved on 2007-11-17] This is the first indication of potential volcanic activity in Canada since around 1830 to 1850 in northwestern British Columbia. [ [http://standeyo.com/NEWS/07_Earth_Changes/071017.CAN.volc.html Canada's Scientists Shaking With Excitement Over Quakes] Retrieved on 2007-11-04]
Volcanism outside Western Canada
Canadian Shield] Volcanism has occurred in other regions, apart from British Columbia and the Yukon. The Canadian Shieldcontains some of the most ancient volcanoes in Canada and on earth. It has over 150 volcanic belts (now deformed and eroded down to nearly flat plains) that range from 600 to 2800 million years old. Each belt probably grew by the coalescence of accumulations erupted from numerous vents, making the tally of volcanoes in the hundreds. Many of Canada's major oredeposits are associated with Precambrianvolcanoes. The Sturgeon Lake Calderain Kenora District, Ontariois one of the world's best preserved mineralized Neoarchean calderacomplexes, which is some 2.7 billion years old. [ [http://www.d.umn.edu/~rmorton/ronshome/Volcanoes/calderas.html Caldera Volcanoes] Retrieved on 2007-07-27] Pillow lavas in the Northwest Territoriesare about 2600 million years old and are preserved in the Cameron River Volcanic Belt. The pillow lavas in rocks over 2 billion years old in the Canadian Shield signify that great oceanic volcanoes existed during the early stages of the formation of the Earth's crust. Ancient volcanoes play an important role in estimating Canada's mineral potential. Many volcanic belts bear oredeposits that are related to the volcanism. Consequently geologists study volcanic belts to understand the volcanoes and the environment in which they erupted, and to provide a working model for mineralexploration.
Some of the most ancient geological remnants of basaltic plains lie in Canada's Precambrian Shield. Eruption of plateau lavas near the
Coppermine Riversouthwest of Coronation Gulfin the Arctic, built an extensive volcanic plateauabout 1200 million years ago with an area of about 170,000 km² (65,000 sq mi) representing a volume of lavas of at least 500,000 cu km (120,000 cu mi).
Slave cratonlocated in the Northwest Territoriescontains the Back River volcanic complex, located 480 km northwest of Yellowknife. It is an Archean stratovolcano, constituting the Back Group of the Yellowknife Supergroup and is somewhat anomalous in the Slave craton because it has undergone only a low degree of deformation and is subhorizontal. The southern half of the complex is exposed at the crest of a small dome. This is the eroded portion of the stratovolcano that has been preserved in an upright position. The complex comprises four volcanic sedimentary sequences (Innerring, Thlewyco, Boucher-Regan, Kelsh) that correspond to the phases of growth and destruction of this stratovolcano.
New England hotspot
About 200 million years ago, just as the
Atlantic Oceanwas beginning to form, the area northwest of Hudson Baywas over the New England hotspot. Kimberlitevolcanoes were formed, carrying diamonds to the Earth's surface. About 50 million years later, as the Atlantic Ocean opened slightly, the hotspot was under present-day Ontario. As the North American Plateslid westward over the hotspot, it created the magma intrusions of the Monteregian Hillsabout 125 million years ago in southern Quebec, Canada- including Mount Royal, in Canada's second-largest city, Montreal. In some cases, magma erupted at the surface, feeding volcanoes that have now completely disappeared. Since that time, erosionhas removed several kilometres of rock. The hills that are visible today represent the magma chambers and part of the conduits through which the molten rock rose toward the surface. Of all these features, Mont Saint-Hilaireis the best known as a source of rare specimens. Location of numerous kimberlite fields and clusters in Ontario and Quebec lie along the continental extension of the New England hotspot track and represents one of the best examples in the world of kimberlite magmatism activated by mantle plumes.
Midcontinent Rift System
Lavaflows created by the Midcontinent Rift Systemin the Lake Superiorarea were formed from basaltic magma. The upwelling of this magma may have been the result of a hotspot which produced a triple junctionin the vicinity of Lake Superior. The hotspot made a dome that covered the Lake Superior area. Voluminous basaltic lava flows erupted from the central axis of the rift, similar to the rifting of the Afar Depressionof the East African Riftsystem. The southwest and southeast extensions represent two arms of the triple junction while a third "failed arm" extends north into Ontario.cite journal
last = Van Schmus
first = W. R.
coauthors = Hinze, W. J.
title = The Midcontinent Rift System
journal = Annual Review of Earth and Planetary Sciences
volume = 13
pages = 345–83
date = May 1985
url = https://kuscholarworks.ku.edu/dspace/bitstream/1808/104/1/fac6cit13.pdf
doi = 10.1146/annurev.ea.13.050185.002021
accessdate = 2007-06-10 ] cite web
last = Kean
first = William F.
title = Keweenawan Rift System
work = Field Trips, Northern Wisconsin and Upper Michigan
publisher = University of Wisconsin-Milwaukee
date = 2000-11-24
url = http://www.uwm.edu/People/wkean/fieldtrip/ArCraig/keewenaw.htm
accessdate = 2007-06-08] This failed arm now forms
Lake Nipigon. It is also possible that the rift is the result of extensional forces behind the continental collision of the Grenville orogenyto the east which in part overlaps the timing of the rift development.
It is likely that later compressive forces from the Grenville orogeny also played a major role in the rift's eventual failure and closure. Had the rifting process continued, the eventual result would have been sundering of the North American craton and creation of a sea. The Midcontinent Rift appears to have progressed almost to the point where the ocean intruded.cite web
last = Reeves
first = T.K.
coauthors = Carroll, Herbert B.
title = Geologic Analysis of Priority Basins for Exploration and Drilling
publisher = U.S. Department of Energy, Office of Scientific and Technical Information
date = April 1999
url = http://www.osti.gov/bridge/servlets/purl/6060-JKD5at/webviewable/6060.PDF
accessdate = 2007-06-10 ] But after about 10-20 million years the rift failed.cite journal
last = Soofi
first = Muhammad A.
coauthors = King, Scott D.
title = Post-rift deformation of the Midcontinent Rift under Grenville tectonism
journal = Tectonophysics
volume = 359
issue = 3
pages = 209–23
publisher = Elsevier
date = 2002-12-06
url = http://web.ics.purdue.edu/~sking/reprints/SoofiKing02.pdf
doi = 10.1016/S0040-1951(02)00512-7
accessdate = 2007-06-10
format = dead link|date=June 2008 – [http://scholar.google.co.uk/scholar?hl=en&lr=&q=author%3A+intitle%3APost-rift+deformation+of+the+Midcontinent+Rift+under+Grenville+tectonism&as_publication=Tectonophysics&as_ylo=&as_yhi=&btnG=Search Scholar search] ] The Midcontinent Rift is the deepest closed or healed rift yet discovered; no deeper rift ever failed to become an ocean.
volcanic rockin the Arctic Cordillerarange from 1.2 billion to 65 million years old. [http://www.ec.ca/soer-ree/English/Vigettes/Terrestrial/ac/land.cfm Landforms and Climate of the Arctic Cordillera Ecozone] Retrieved on 2007-09-26] The Late Cretaceousvolcanics of northern Ellesmere Island has been uncertainly associated to both the early volcanic activity of the Iceland hotspotand the Alpha Ridge. Even though these volcanics are about 90 million years old, the volcanoes and cinderare still able to be seen. [ [http://www.earth.rochester.edu/pmag/arctic/arctic99/journalchris.html Chris's journal entries] Retrieved on 2007-08-05]
The Late Cretaceous
Strand Fiord Formationon Axel Heiberg Islandis interpreted to represent the cratonward extension of the Alpha Ridge, a volcanic ridge that was active during the formation of the Amerasian Basin. [http://www.blackwell-synergy.com/doi/abs/10.1111/j.1751-8369.1985.tb00497.x Volcanic style in the Strand Fiord Formation (Upper Cretaceous), Axel Heiberg Island, Canadian Arctic Archipelago] Retrieved on 2007-08-15] The formation contains flood basalts which are found at Dragon Cliffs300 meters tall. It contains columnar jointing units that are usually 1 to 3 meters in diameter.
Bravo Lake Formationon central Baffin Islandis a rare alkaline-suite that formed as a result of submarine rifting during the Paleoproterozoicperiod. [ [http://gac.esd.mun.ca/gac_2004/search_abs/sub_program.asp?sess=98&form=10&abs_no=280 Volcanology and geochemistry of the Bravo Lake Formation, Baffin Island, Nunavut] . Retrieved on 2007-11-05] Its lavas display geochemical characteristics similar to modern ocean-island-basalt groups. The range from moderately to intensely fractionated REE-profiles is similar to that from tholeiitic basalts to extremely alkalinelavas in Hawaii. Geochemical results of pillow lavas and chill boundaries along five transects across the Bravo Lake Formation suggest the existence of three chemically different magmatypes within the volcanic belt. [ [http://gsc.nrcan.gc.ca/baffin4d/proj/p21_e.php Central Baffin Island 4-D Project - Projects] : Paleoproterozoic mafic magmatism in central Baffin Island. Retrieved on 2007-10-18]
About 190 million years years ago, just as the
supercontinent Pangaeabegan to break up, a rift valleyformed. As the riftbegan to separate from mainland North America, volcanic activity occurred forming volcanoes and flood basalts. These flood basalts poured out over the landscape, covering much of southern Nova Scotia. Sections of these flood basalts has been eroded away, but still form a basaltic mountain rangeknown as North Mountain. The rift valley eventually failed as the Mid-Atlantic Ridgecontinued to separate North America and Europe, forming the Bay of Fundy.
The North Mountain volcanic range on the mainland portion of southwestern Nova Scotia, is a 201 million year old sequence of
tholeiitic basalts, which contains columnar jointing and forms the northern edge of Annapolis Valleyalong the shore of the Bay of Fundy. The basalts also extend under the Bay of Fundy and parts of it are exposed on the shore at Five Islands, east of Parrsboro on the north side of the bay. [ [http://www.stmarys.ca/conted/webcourses/GEO/GEO99/pubigneous/rifts.html Hot Spots and Rifts in Continental Crust] Retrieved on 2007-10-15] Numerous sediment-filled fissures are present near the upper surface of the range. North Mountain is believed to have formed during the opening of the Atlantic Ocean. [ [http://www.ldeo.columbia.edu/~polsen/nbcp/northmt1.html North Mountain Basalt] Retrieved on 2007-10-15] It is a portion of the Central Atlantic Magmatic Province, which is a gigantic flood basaltand intrusive complex along east coast of the United States, Europe, northwest Africaand South Americawith an area of 4,000 km³. A viscous (<175 m) North Mountain flow at McKay Headshows ~25-cm-thick distinguished layers separated by ~130 centimeter of basaltin its upper 34 meters. Upper layers (5 meters below the lavatop) are extremely vesicular while lower ones are pegmatitic and includes a narrow (~2 cm) rhyoliteband. The layering of the flow closely resemble that of some Hawaiian lava lakes. [ [http://www.springerlink.com/content/g2p9qp370r4406x2/ Cooling history and differentiation of a thick North Mountain Basalt flow (Nova Scotia, Canada)] Retrieved on 2007-10-15]
New Brunswicklies the large 17 x 12 kilometer eroded Late Devonian Mount Pleasant Caldera. It is one of few noticeable pre- Cenozoiccalderas. Its formation is associated to a period of crustal thinning that followed the Acadian orogenyin the northern Appalachian Mountains.
Large igneous provinces
Canada has a rich record of
large igneous provinces. At least 80 candidates are recognized in Canada and adjacent regions, with ages ranging from 3100 to 17 million years old. In the Paleozoicand Proterozoic, Large igneous provinces are typically deeply eroded. They are represented by deep-level plumbing systems consisting of giant dike swarms, sill provinces and layered intrusions. In the Archean the most promising Large igneous province candidates are greenstone belts containing komatiites. In Canada, most greenstone belts are related to mantle plumes.
The 1.2 billion year old
Mackenzie dike swarmis the largest dike swarmknown on Earth, [ [http://gdcinfo.agg.nrcan.gc.ca/app/dyke/index_e.html Supressing Varying Directional Trends] Retrieved on 2007-11-05] more than 500 kilometers (311 miles) wide and 3,000 kilometers (1,864 miles) long, extending in a northwesterly direction across the whole of Canada from the Arcticto the Great Lakes.
Bennett Lake Volcanic Complex
Level Mountain Range
Mount Pleasant Caldera
Sturgeon Lake Caldera
Blake River Megacaldera Complex
List of volcanoes in Canada
Geography of Canada
Geology of the Pacific Northwest
* [http://gsc.nrcan.gc.ca/volcanoes/intro_e.php Volcanoes of Canada - Introduction]
* [http://vulcan.wr.usgs.gov/Volcanoes/Canada/description_canadian_volcanics.html CVO Website - Canada Volcanoes and Volcanics]
* [http://www.cgu-ugc.ca/cnc-iugg/IAVCEI99.htm Volcanism in Canada]
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