Mackenzie hotspot

The Mackenzie hotspot was a volcanic hotspot that existed about 1.3 billion years ago across Canada from the Northwest Territories and Nunavut.

MLIP igneous figures
Tectonic and magmatic features associated with the Mackenzie Large Igneous Province, including the rifting that created the Poseidon Ocean. Red star shows the initial Mackenzie plume zone relative to the lithosphere.

Extent

The Mackenzie hotspot is responsible for the creation of the Mackenzie Large Igneous Province, which contains the largest dike swarm on Earth.[1] During its formation, eruption of plateau lavas near the Coppermine River, built an extensive volcanic plateau about 1,200 million years ago with an area of about 170,000 km2 (66,000 sq mi) representing a volume of lavas of at least 500,000 km3 (120,000 cu mi).

The Mackenzie hotspot also resulted in the opening of the Mesoproterozoic Poseidon Ocean.

See also

References

  1. ^ 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.
Hotspot (geology)

In geology, the places known as hotspots or hot spots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. Their position on the Earth's surface is independent of tectonic plate boundaries. There are two hypotheses that attempt to explain their origins. One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. The other hypothesis is that lithospheric extension permits the passive rising of melt from shallow depths. This hypothesis considers the term "hotspot" to be a misnomer, asserting that the mantle source beneath them is, in fact, not anomalously hot at all. Well-known examples include the Hawaii, Iceland and Yellowstone hotspots.

Large igneous province

A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics. The formation of some of the LIPs the past 500 million years coincide in time with mass extinctions and rapid climatic changes, which has led to numerous hypotheses about the causal relationships. LIPs are fundamentally different from any other currently active volcanoes or volcanic systems.

Lava field

A lava field, also called a lava plain or lava bed, is a large expanse of nearly flat-lying lava flows. Such features are generally composed of highly fluid basalt lava, and can extend for tens or even hundreds of miles across the underlying terrain. The extent of large lava fields is most readily grasped from the air or in satellite photos, where their typically dark, nearly black color contrasts sharply with the rest of the landscape.

According to the US Geological Survey, monogenetic volcanic fields are collections of cinder cones, and/or maar vents and associated lava flows and pyroclastic deposits. Sometimes a stratovolcano

is at the center of the field, as at the San Francisco Volcanic Field in Arizona.

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 plateau about 1200 million years ago with an area of about 170,000 km2 (66,000 sq mi), representing a volume of lavas of at least 500,000 km3 (120,000 cu mi). The lavas are thought to have originated from a mantle plume center called the Mackenzie hotspot.

List of Scottish place names in Canada

This is a list of placenames in Scotland that have been applied to parts of Canada by Scottish emigrants or explorers.

For Nova Scotian names in Scottish Gaelic (not necessarily the same as the English versions) see Canadian communities with Scottish Gaelic speakers and Scottish Gaelic placenames in Canada

Note that, unless otherwise stated, province names are not Scottish.

Mackenzie Large Igneous Province

The Mackenzie Large Igneous Province (MLIP) is a major Mesoproterozoic large igneous province of the southwestern, western and northwestern Canadian Shield in Canada. It consists of a group of related igneous rocks that were formed during a massive igneous event starting about 1,270 million years ago. The large igneous province extends from the Arctic in Nunavut to near the Great Lakes in Northwestern Ontario where it meets with the smaller Matachewan dike swarm. Included in the Mackenzie Large Igneous Province are the large Muskox layered intrusion, the Coppermine River flood basalt sequence and the massive northwesterly trending Mackenzie dike swarm.

As a large igneous province, it is an extremely large area of related igneous rocks that were emplaced over an extremely short geological time span. The igneous rocks comprising the Mackenzie Large Igneous Province originated from processes not associated with normal plate tectonics and seafloor spreading. It is one of the several large igneous provinces scattered throughout the Canadian landscape, which can be thousands of kilometres in volume and area. The Mackenzie Large Igneous Province is one of the world's largest Proterozoic magmatic provinces, as well as one of the most well-preserved continental flood basalt terrains on Earth. Igneous rocks of the Mackenzie Large Igneous Province are generally mafic in composition, including basalt and gabbro.

Even though the Mackenzie Large Igneous Province is classified as a large igneous province like other extremely large accumulations of igneous rocks on Earth, it is much larger than large igneous province standards. The standard size classification for large igneous provinces is a minimum areal extent of 100,000 km2 (39,000 sq mi). However, the Mackenzie dike swarm itself occupies an area of at least 2,700,000 km2 (1,000,000 sq mi), making the Mackenzie Large Igneous Province larger than the Ontong Java Plateau (in the southwestern Pacific Ocean) and the U.S. state of Alaska.

Mackenzie dike swarm

The Mackenzie dike swarm, also called the Mackenzie dikes, form a large igneous province in the western Canadian Shield of Canada. It is part of the larger Mackenzie Large Igneous Province and is one of more than three dozen dike swarms in various parts of the Canadian Shield.

The Mackenzie dike swarm is the largest dike swarm known on Earth, more than 500 km (310 mi) wide and 3,000 km (1,900 mi) long, extending in a northwesterly direction across the whole of Canada from the Arctic to the Great Lakes. The mafic dikes cut Archean and Proterozoic rocks, including those in the Athabasca Basin in Saskatchewan, Thelon Basin in Nunavut and the Baker Lake Basin in the Northwest Territories.

The source for the Mackenzie dike swarm is considered to have been a mantle plume center called the Mackenzie hotspot. About 1,268 million years ago, the Slave craton was partly uplifted and intruded by the giant Mackenzie dike swarm. This was the last major event to affect the core of the Slave craton, although later on some younger mafic magmatism registered along its edges.

Matachewan hotspot

The Matachewan hotspot was a volcanic hotspot responsible for the creation of the large 2,500 to 2,450 million year old Matachewan dike swarm, as well as continental rifting of the Superior and Hearne cratons during the Paleoproterozoic period.

Muskox intrusion

The Muskox intrusion is a layered intrusion in Nunavut, Canada. It is located 144 km (89 mi) northeast of Great Bear Lake and 90 km (56 mi) south of Kugluktuk on Coronation Gulf. It was formed during a large magmatic event during the Proterozoic by hotspot or mantle plume volcanism that emplaced the widespread Coppermine River Group flood basalts.

The intrusion is a tilted trough shaped body with an exposed length of 120 km (75 mi) and a thickness or original vertical dimension of over 6 km (3.7 mi). Rock types include picrite, peridotite, dunite, pyroxenite, gabbro and granophyre. A feeder dike of olivine gabbro is exposed "below" the now tilted sequence.Potassium argon dating in the region provides an age of 1095 - 1155 Ma for the Muskox intrusion, 1100 - 1200 Ma for the Mackenzie dike swarm and 740 - 1200 Ma for the Coppermine basalt flows (younger dates are interpreted as having been reset by later intrusion of gabbro sills at 604 - 718 Ma). Further stratigraphic and structural evidence provides further support that the Muskox, the MacKenzie dikes and the Coppermine flows are of the same magmatic event that formed the Mackenzie Large Igneous Province and the Muskox is interpreted as occupying the magma chamber which fed the volcanism.

Poseidon Ocean

The Poseidon Ocean was an ocean that existed during the Mesoproterozoic period (from 1.6 to 1.0 billion years ago) of the geologic timescale. It began to form when a hotspot collided with lithosphere that was already in an extensional regime that allowed rifting to occur at the onset of hotspot volcanism that created the Mackenzie Large Igneous Province. This hotspot, known as the Mackenzie hotspot, produced passive rifting to form a triple junction. As two of the rift arms continued to grow, they created the Poseidon Ocean basin. The third rift arm failed to open fully, creating an aulacogen.

Volcanology of Canada

Volcanology of Canada includes lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes, and maars, along with examples of more less common volcanic forms such as tuyas and subglacial mounds. It has a very complex volcanological history spanning from the Precambrian eon at least 3.11 billion years ago when this part of the North American continent began to form.Although the country's volcanic activity dates back to the Precambrian eon, volcanism continues to occur in Western and Northern Canada where it forms part of an encircling chain of volcanoes and frequent earthquakes around the Pacific Ocean called the Pacific Ring of Fire. But because volcanoes in Western and Northern Canada are in remote rugged areas and the level of volcanic activity is less frequent than with other volcanoes around the Pacific Ocean, Canada is commonly thought to occupy a gap in the Pacific Ring of Fire between the volcanoes of western United States to the south and the Aleutian volcanoes of Alaska to the north. However, the mountainous landscape of Western and Northern Canada includes more than 100 volcanoes that have been active during the past two million years and whose eruptions have claimed many lives. Volcanic activity has been responsible for many of Canada's geological and geographical features and mineralization, including the nucleus of North America called the Canadian Shield.

Volcanism has led to the formation of hundreds of volcanic areas and extensive lava formations across Canada, indicating volcanism played a major role in shaping its surface. 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. They are 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 (3,800–2,500 million years ago) age greenstone belts containing a rare volcanic rock called komatiite.

Volcanology of Northern Canada

Volcanology of Northern Canada includes hundreds of volcanic areas and extensive lava formations across Northern Canada. The region'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. Northern Canada has a record of very large volumes of magmatic rock called large igneous provinces. They are represented by deep-level plumbing systems consisting of giant dike swarms, sill provinces and layered intrusions.

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