Volcanic activity is a major part of the geology of Canada and is characterized by many types of volcanic landform, including lava flows, volcanic plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes, and maars, along with less common volcanic forms such as tuyas and subglacial mounds. Though Canada's volcanic history dates back to the Precambrian eon, at least 3.11 billion years ago, when its part of the North American continent began to form, volcanism continues to occur in Western and Northern Canada in modern times, where it forms part of an encircling chain of volcanoes and frequent earthquakes around the Pacific Ocean called the Pacific Ring of Fire. Because volcanoes in Western and Northern Canada are in relatively remote and sparsely populated areas and their activity is less frequent than with other volcanoes around the Pacific Ocean, Canada is commonly thought to occupy a gap in the Ring of Fire between the volcanoes of the western United States to the south and the Aleutian volcanoes of Alaska to the north. Even so, the mountainous landscapes of the Canadian provinces of Alberta, British Columbia, Yukon, and the Northwest Territories include more than 100 volcanoes that have been active during the past two million years and whose eruptions have claimed many lives. Volcanic activity is responsible for many of Canada's geological and geographical features and mineralization, including the nucleus of the North American continent, known as the Canadian Shield. Volcanism has led to the formation of hundreds of volcanic areas and extensive lava formations across Canada. The country's different volcano and lava types originate from different tectonic settings and types of volcanic eruptions, ranging from passive lava eruptions to violent explosive eruptions. Canada has a rich record of very large volumes of magmatic rock called large igneous provinces, represented by deep-level plumbing systems consisting of giant dike swarms, sill provinces and layered intrusions. The most capable large igneous provinces in Canada are Archean greenstone belts estimated at 3.8 to 2.5 billion years old, containing a rare volcanic rock called komatiite.
Eruption styles and volcano formations
Eastern Canada
The 2,677‑million-year-old Abitibi greenstone belt in Ontario and Quebec is one of the largest Archean greenstone belts on Earth and one of the youngest parts of the Superior craton which sequentially forms part of the Canadian Shield. Komatiite lavas in the Abitibi greenstone belt (pictured) occur in four lithotectonic assemblages known as Pacaud, Stoughton-Roquemaure, Kidd-Munro and Tisdale. The Swayze greenstone belt further south is interpreted to be a southwestern extension of the Abitibi greenstone belt. The Archean Red Lake greenstone belt in western Ontario consists of basaltic and komatiitic volcanics ranging in age from 2,925 to 2,940 million years old and younger rhyolite-andesite volcanics ranging in age from 2,730 to 2,750 million years old. It is situated in the western portion of the Uchi Subprovince, a volcanic sequence comprising a number of greenstone belts.
The 1884- to 1870‑million-year-old Circum-Superior Belt constitutes a large igneous province extending for more than 3,400 kilometres (2,100 mi) from the Labrador Trough in Labrador and northeastern Quebec though the Cape Smith Belt in northern Quebec, the Belcher Islands in southern Nunavut, the Fox River and Thompson belts in northern Manitoba, the Winnipegosis komatiite belt in central Manitoba, and on the southern side of the Superior craton in the Animikie Basin of northwestern Ontario. Two volcano-sedimentary sequences exist in the Labrador Trough with ages of 2,170–2,140 million years and 1,883–1,870 million years. In the Cape Smith Belt, two volcanic groups range in age from 2,040 to 1,870 million years old called the Povungnituk volcano-sedimentary Group and the Chukotat Group. The Belcher Islands in eastern Hudson Bay contain two volcanic sequences known as the Flaherty and Eskimo volcanics. The Fox River Belt consists of volcanics, sills and sediments some 1,883 million years old while magmatism of the Thompson Belt is dated to 1,880 million years old. To the south lies the 1,864‑million-year-old Winnipegosis komatiites. In the Animikie Basin near Lake Superior, volcanism is dated 1,880 million years old.
During the Mesoproterozoic era of the Precambrian eon 1,109 million years ago, northwestern Ontario began to split apart to form the Midcontinent Rift System, also called the Keweenawan Rift. Lava flows created by the rift in the Lake Superior area were formed from basaltic magma. The upwelling of this magma was 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 that formed the Atlantic Ocean. A failed arm extends 150 kilometres (93 mi) north into mainland Ontario where it forms a geological formation known as the Nipigon Embayment. This failed arm includes Lake Nipigon, the largest lake entirely within the boundaries of Ontario.
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