Volcanism in Canada

Canada has examples of almost every type of volcano found 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 Pleistocene or Holocene epochs, 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 Precambrian era, activity continues today with eruptions occurring in Western Canada approximately 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 Fire between the Cascade Volcanic Arc of the western United States and the Aleutian volcanoes of Alaska, yet British Columbia and Yukon include more than 100 separate volcanic centers that have been active during the Quaternary.

Volcanism in Western Canada

Western Canada lies 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).

Numerous shield volcanoes developed during the Tertiary period in north-central British Columbia and some were active intermittently to recent times. Mount Edziza and Level Mountain are most spectacular examples. Mount Edziza is a stratovolcano consisting 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:

The Garibaldi Volcanic Belt is 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 Rainier and Mount St. Helens), and contains the most explosive young volcanoes in Canada. It was formed by subduction of the Juan de Fuca Plate at the Cascadia subduction zone. Eruption styles within the belt range from effusive to explosive, with compositions from basalt to 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 stratosphere and dammed the Lillooet River with breccia. The Garibaldi Volcanic Belt contains two further volcanic fields, the Franklin Glacier Volcano and 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.

The Anahim Volcanic Belt is an east-west line of volcanoes stretching from just north of Vancouver Island to near Quesnel, British Columbia. These volcanoes probably formed when the North American Plate moved over a hotspot, similar to the one feeding the Hawaiian Islands called the Anahim hotspot. It contains three major shield volcanoes called the Rainbow Range, Ilgachuz Range and Itcha Range. The last volcanic eruption within the belt was about 7000 years ago at a small tree-covered cinder cone called Nazko Cone. The volcano's oldest eruption is approximately 340,000 years old.

The 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 Plate and the North American Plate. The Fort Selkirk Volcanic Field is 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 Holocene or older.

The Chilcotin Plateau Basalts in 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 Pleistocene period.

The Wells Gray-Clearwater Volcanic Field in southeastern British Columbia consists of numerous small, basaltic volcanoes and extensive lava flows. 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 Mountain in 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] ]

The Wrangell Volcanic Field lies mostly in Alaska, but extends into southeastern Yukon. It was formed by subduction of the Pacific Plate beneath the North American Plate at 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.

Eruptions of basaltic to rhyolitic volcanoes and hypabyssal rocks of the Alert Bay Volcanic Belt in northern Vancouver Island are 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 Pliocene and Pleistocene time. However, no Holocene eruptions are known, and volcanic activity in the belt has likely ceased.

Monitoring Canadian volcanoes

Volcano monitoring in 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 earthquake monitoring, 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 Canada has 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 Mountain erupted 7050 BP.
* Mount Meager erupted 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 Field in 1500.
* The Tseax River Cone erupted in 1775.
* Ruby Mountain might have erupted in 1898.
* Lava Fork Valley might have erupted in 1904.

Western Canada is 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 Mountain and 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 magma plumbing 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 Meager and Mount Edziza.

The 1775 eruption of the Tseax River Cone is 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 Alaska and dammed the Blue River. The Nass River valley 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 Cone which 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 magma because 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

[
left|thumb|Canadian Shield] Volcanism has occurred in other regions, apart from British Columbia and the Yukon. The Canadian Shield contains 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 ore deposits are associated with Precambrian volcanoes. The Sturgeon Lake Caldera in Kenora District, Ontario is one of the world's best preserved mineralized Neoarchean caldera complexes, 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 Territories are 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 ore deposits 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 mineral exploration.

Some of the most ancient geological remnants of basaltic plains lie in Canada's Precambrian Shield. Eruption of plateau lavas near the Coppermine River southwest of Coronation Gulf in the Arctic, built an extensive volcanic plateau about 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).

The Slave craton located in the Northwest Territories contains 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 Ocean was beginning to form, the area northwest of Hudson Bay was over the New England hotspot. Kimberlite volcanoes 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 Plate slid westward over the hotspot, it created the magma intrusions of the Monteregian Hills about 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, erosion has 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-Hilaire is 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

Lava flows created by the Midcontinent Rift System in the Lake Superior area were formed from basaltic magma. The upwelling of this magma may have been the result of a hotspot which produced a triple junction in 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 Depression of the East African Rift system. 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.
authorlink =
coauthors = Hinze, W. J.
title = The Midcontinent Rift System
journal = Annual Review of Earth and Planetary Sciences
volume = 13
issue =
pages = 345–83
publisher =
date = May 1985
url = https://kuscholarworks.ku.edu/dspace/bitstream/1808/104/1/fac6cit13.pdf
doi = 10.1146/annurev.ea.13.050185.002021
id =
accessdate = 2007-06-10 ] cite web
last = Kean
first = William F.
authorlink =
coauthors =
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
format =
doi =
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 orogeny to 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.
authorlink =
coauthors = Carroll, Herbert B.
title = Geologic Analysis of Priority Basins for Exploration and Drilling
work =
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
format =
doi =
accessdate = 2007-06-10 ] But after about 10-20 million years the rift failed.cite journal
last = Soofi
first = Muhammad A.
authorlink =
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
id =
accessdate = 2007-06-10
format = dead link|date=June 2008 &ndash; ^{[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.

Canadian Arctic

Mountains of volcanic rock in the Arctic Cordillera range 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 Cretaceous volcanics of northern Ellesmere Island has been uncertainly associated to both the early volcanic activity of the Iceland hotspot and the Alpha Ridge. Even though these volcanics are about 90 million years old, the volcanoes and cinder are 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 Formation on Axel Heiberg Island is 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 Cliffs 300 meters tall. It contains columnar jointing units that are usually 1 to 3 meters in diameter.

The Bravo Lake Formation on central Baffin Island is a rare alkaline-suite that formed as a result of submarine rifting during the Paleoproterozoic period. [ [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 alkaline lavas 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 magma types 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]

Eastern Canada

About 190 million years years ago, just as the supercontinent Pangaea began to break up, a rift valley formed. As the rift began 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 range known as North Mountain. The rift valley eventually failed as the Mid-Atlantic Ridge continued 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 Valley along 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 basalt and intrusive complex along east coast of the United States, Europe, northwest Africa and South America with an area of 4,000 km³. A viscous (<175 m) North Mountain flow at McKay Head shows ~25-cm-thick distinguished layers separated by ~130 centimeter of basalt in its upper 34 meters. Upper layers (5 meters below the lava top) are extremely vesicular while lower ones are pegmatitic and includes a narrow (~2 cm) rhyolite band. 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]

In southwestern New Brunswick lies the large 17 x 12 kilometer eroded Late Devonian Mount Pleasant Caldera. It is one of few noticeable pre-Cenozoic calderas. Its formation is associated to a period of crustal thinning that followed the Acadian orogeny in 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 Paleozoic and 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 swarm is the largest dike swarm known 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 Arctic to the Great Lakes.

Major volcanoes

*Mount Edziza
*Mount Meager
*Ilgachuz Range
*Itcha Range
*Rainbow Range
*Bennett Lake Volcanic Complex
*Level Mountain Range
*Mount Garibaldi
*Mount Cayley
*Mount Silverthrone
*Mount Pleasant Caldera
*Sturgeon Lake Caldera
*Blake River Megacaldera Complex

ee also

*List of volcanoes in Canada
*Canadian Shield
*Cascade Volcanoes
*Geography of Canada
*Geology of the Pacific Northwest

Major eruptions

Notes: pf=pyroclastic flows, lf=lava flows, lm=lahar mudflows, ex=explosive eruption ld=lava dome collapse, cc=caldera collapse, fl=Flood.

References

External links

* [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]