Mackenzie Large Igneous Province

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Mackenzie Large Igneous Province
Mackenzie Large Igneous Province.png
Map of the Mackenzie Large Igneous Province and its sub-features. Blue star marks the approximate focal point for 1,270 magmatic activity.
Country Canada
Regions Northwest Territories, Nunavut, Yukon, Ontario, Manitoba, Saskatchewan
Part of Canadian Shield
Area 2,700,000 km² (1,042,476 sq mi)
Period Mesoproterozoic

The Mackenzie Large Igneous Province (MLIP) is a major Mesoproterozoic large igneous province of southwestern, western and northwestern Canada. It is a group of igneous rocks which 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.

MLIP is one of the largest Proterozoic magmatic provinces on Earth, as well as the world's largest and best-preserved continental flood basalt terrain.[1] This huge area of igneous rock was spewed out in a short time, geologically speaking. The MILP is much larger than other well-preserved large igneous provinces. The standard size classification for large igneous provinces is a minimum of 100,000 km2 (39,000 sq mi). However, the Mackenzie dyke 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 or the U.S. state of Alaska.[2]

The Mackenzie Large Igneous Province was caused by processes other than normal plate tectonics and seafloor spreading. Igneous rocks of the Mackenzie Large Igneous Province are generally mafic in composition, including basalt and gabbro.

Origins[change | change source]

Like most large igneous provinces, the Mackenzie Large Igneous Province was caused by a mantle plume—an upwelling zone of abnormally hot rock within the Earth's mantle. As the head of the Mackenzie plume reached the Earth's lithosphere, it spread out and melted catastrophically to form large volumes of basaltic magma. This resulted in the creation of a stationary volcanic zone west of Victoria Island, called the Mackenzie hotspot.[3]

Coppermine River Group[change | change source]

The Coppermine River Group is a sequence of Mesoproterozoic continental flood basalts forming part of the Mackenzie Large Igneous Province in the Northwest Territories and Nunavut, Canada. It is one of the largest flood basalt provinces on Earth, covering the area with a volume of approximately 650,000 km3 (155,943 cu mi).[4]

Between 1,200 and 740 million years ago, a series of flood basalt eruptions took place. At the northern portion of the Mackenzie Large Igneous Province, vast volumes of basaltic lava paved over a large area of the northwestern Canadian Shield. This extensive volcanism constructed a large lava plateau with an area of 170,000 km2 (66,000 sq mi), representing a volume of lavas of at least 500,000 km3 (120,000 cubic miles).[5] This extensive area of flood basalt lava flows has been termed the Coppermine River flood basalts hence given the location of the flood basalt sequence. With an area of 170,000 km2 (66,000 sq mi) and a volume of 650,000 km3 (120,000 cubic miles), the Coppermine River flood basalt sequence is larger than the Columbia River Basalt Group in the United States and comparable in size to the Deccan Traps in west-central India. This makes the Coppermine River flood basalts one of the largest flood basalt events ever to appear on the North American continent, as well as on Earth. The maximum thickness of the Coppermine River flood basalts is 4.7 km (2.9 mi) and consist of 150 lava flows, each 4 m (13 ft) to 100 m (330 ft) thick.[6]

The Coppermine River flood basalts were extruded shorty after a period of crustal uplift that later resulted in a short period of collapse in the associated landscape.[3] This sudden uplift was likely caused by rising magma of the Mackenzie plume, which later resulted in the appearance of the Mackenzie hotspot. The Coppermine River basalts comprising more than 100 individual lava flows.

References[change | change source]

  1. Muskox Property. Prize Mining Corporation. [1]
  2. Day J.M. 2008. The 1.27 Ga Mackenzie Large Igneous Province and Muskox layered intrusion. Large Igneous Provinces Commission. [2]
  3. 3.0 3.1 Ernst, Richard E. & Buchan, Kenneth L. 2001. Mantle plumes: their identification through time. Geological Society of America. pp. 143/8, 259. ISBN 0-8137-2352-3.
  4. Geological Report on the Muskox Property
  5. Lambert, Maurice B. 1978. Volcanoes. North Vancouver, British Columbia: Energy, Mines and Resources Canada. ISBN 0-88894-227-3.
  6. Yoshida M; Windley B.F & Dasgupta S. 2003. Proterozoic East Gondwana: supercontinent assembly and breakup. The Geological Society. p. 26. ISBN 1-86239-125-4.