Mackenzie Large Igneous Province
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.
| Mackenzie Large Igneous Province | |
|---|---|
 | |
| Location | Northwest Territories, Canada |
| Area | 2,700,000 km2 (1,000,000 sq mi) |
| Age | Mesoproterozoic |
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 square kilometres (39,000 square miles). However, the Mackenzie dyke swarm itself occupies an area of at least 2,700,000 square kilometres (1,000,000 square miles), 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
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
The Coppermine River Group is a sequence of Mesoproterozoic continental flood basalts. They are part of the Mackenzie Large Igneous Province in the Northwest Territories and Nunavut, Canada. This is one of the largest flood basalt provinces on Earth, covering the area with a volume of approximately 650,000 cubic kilometres (155,943 cubic miles).[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 part of the northwestern Canadian Shield. This constructed a large lava plateau with an area of 170,000 square kilometres (66,000 square miles), 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 called the Coppermine River flood basalts. With an area of 170,000 square kilometres (66,000 square miles) 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. It compares 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 kilometres (2.9 miles) and has 150 lava flows, each 4 metres (13 feet) to 100 metres (330 feet) thick.[6]
The Coppermine River flood basalts occurred shortly after a period of crustal uplift. The uplift then collapsed.[3] This sudden uplift was likely caused by rising magma of the Mackenzie plume, which caused the Mackenzie hotspot. The Coppermine River basalts show over 100 individual lava flows.
Mackenzie Large Igneous Province Media
Tectonic and magmatic features associated with the Mackenzie Large Igneous Province. Red star shows the initial Mackenzie plume zone relative to the lithosphere; partial black circle is the estimate of the zone of plume influence on stress-field orientation; dark lines are dikes of the Mackenzie swarm; CRB indicates the Coppermine River basalts; M indicates the Muskox intrusion.
Geologic map of the Muskox intrusion and adjacent geologic groups
Map of the 1,267 million year old northwest trending Mackenzie dike swarm (black lines). Dots indicate areas where flow direction was determined. Red arcuate line indicates boundary between vertical flow and horizontal flow.
References
- ↑ Muskox Property. Prize Mining Corporation. [1] Archived 2009-04-08 at the Wayback Machine
- ↑ Day J.M. 2008. The 1.27 Ga Mackenzie Large Igneous Province and Muskox layered intrusion. Large Igneous Provinces Commission. [2]
- ↑ 3.0 3.1 Ernst, Richard E. & Buchan, Kenneth L. 2001 (January 2001). Mantle plumes: their identification through time. Geological Society of America. pp. 143/8, 259. ISBN 0-8137-2352-3.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ↑ "Geological Report on the Muskox Property" (PDF). Archived from the original (PDF) on 2011-07-15. Retrieved 2013-01-15.
- ↑ Lambert, Maurice B. 1978 (1978). Volcanoes. North Vancouver, British Columbia: Energy, Mines and Resources Canada. ISBN 0-88894-227-3.
- ↑ Yoshida M; Windley B.F & Dasgupta S. 2003 (2003). Proterozoic East Gondwana: supercontinent assembly and breakup. The Geological Society. p. 26. ISBN 1-86239-125-4. Retrieved 2008-12-15.
{{cite book}}: CS1 maint: multiple names: authors list (link)