Large igneous province
1589341
219810703
2008-06-16T23:47:13Z
193.190.253.149
other languages: more close description in Nederlands
{{Nofootnotes|article|date=February 2008}}
'''Large [[Igneous rock|Igneous]] provinces''' (LIPS) were originally defined by Coffin and Eldholm (1992) as areas of [[Earth's crust|Earth's surface]] that contain very large volumes of magmatic rocks (typically [[basalt]] but including [[rhyolite]]s) erupted over extremely short [[geological time]] intervals of a few million years or less. These provinces are not associated with normal [[plate tectonic]] magmatism, ie, [[mid-ocean ridge]]s and [[island arc]]s. LIPS include continental [[flood basalt]]s, [[oceanic plateau]]s, large [[dike swarm]]s (the eroded roots of a volcanic province), and [[volcanic margin|volcanic rifted margins]], recognized by the presence of dike swarms and "seaward dipping reflectors" -- seismically-imaged tabular features buried deep beneath sediment that lie parallel to a passive [[continental margin]] along the [[continental slope]], and interpreted to represent [[lava]] flows or sills that formed during rifting of the continent). Most LIPS consist of basalt, but some contain large volumes of associated rhyolite; the rhyolite is typically very dry compared to island arc rhyolites, with much higher eruption temperatures (850º to 1000º C) than normal rhyolites.
When created, LIPS often occupy a few million km² and have volumes on the order of 1 million km<sup>3</sup>. In most cases, the majority of a LIP's volume is emplaced in less than 1 million years. One of the conundra of LIPS origins is to understand how enormous volumes of basaltic magma are formed and erupted over such short time scales, with effusion rates up to an order of magnitude greater than mid-ocean ridge basalts.
==Theories of formation==
Large igneous provinces are often linked to active [[Hotspot (geology)|hotspots]] by linear chains of volcanic islands or volcanoes, leading to models that connect their origins to [[mantle plume]]s. In this hypothesis, mantle plumes consist of a bulbous head and a thin tail that feeds hot mantle into the head. When the rising plume head encounters the lithosphere, it spreads out and melts catastrophically to form large volumes of basalt magma in 1-2 million years. Subsequent volcanism originates with the plume tail. The movement of lithosphere across the surface of the Earth in response to plate tectonics causes the plume tail volcanics to form linear island chains. The impact of the plume on the base of continental lithosphere may cause rifting and breakup of the continent, creating conjugate LIPS on opposite sides of an ocean basin (e.g., the Parana-Etendeka pair of South America-Africa).
Alternate theories include delamination of eclogitic lower crust, edge effects of thick lithosphere, and meteorite impact (see [[Mantle plume]]s for more complete discussion of alternate models).
===Relationship to extinction events===
Because a LIP may in several cases have occurred simultaneously with [[oceanic anoxic event]]s and [[extinction event]]s, it has been proposed that the volcanic byproducts of LIP formation may have had a profound and deleterious effect on the global environment, perhaps contributing to extinction events. The most important examples are the [[Deccan Traps]] ([[Cretaceous–Tertiary extinction event]]), the [[Karoo-Ferrar]] ([[Pliensbachian-Toarcian extinction]]), the [[Central Atlantic Magmatic Province]] ([[Triassic-Jurassic extinction event]]), and the [[Siberian traps]] ([[Permian-Triassic extinction event]]).
LIPS have two impacts on environment that can cause extinction: first, they release large volumes of sulfate gas that forms sulfuric acid in the atmosphere; this absorbs heat and causes substantial cooling (e.g., the [[Laki (volcano)|Laki]] eruption in Iceland, 1783). Second, oceanic LIPS can reduce oxygen in seawater by either direct oxidation reactions with metals in hydrothermal fluids or by causing algal blooms that consume large amounts of oxygen (Kerr, 2005).
==Examples of LIPs==
These are well documented large igneous provinces in geological research.
'''Continental Flood basalts'''
*[[Ethiopian Highlands]]
*[[Columbia River Basalt Group]]
*[[Chilcotin Plateau Basalts]] (south-central British Columbia, Canada)
*[[Deccan Traps]] (India)
*[[Paraná and Etendeka traps]] (Brazil-Namibia)
*[[Brazilian Highlands]]
*[[Rio de la Plata Craton]] (Uruguay)
*[[Karoo-Ferrar]] (South Africa-Antarctica)
*[[Siberian Traps]] (Russia)
*[[Emeishan Traps]] (western China)
'''Oceanic Plateaux'''
*[[Caribbean large igneous province]] (Caribbean Sea)
*[[Kerguelen Plateau]] (Indian Ocean)
*[[Ontong Java Plateau]], [[Manihiki Plateau]] and [[Hikurangi Plateau]] (southwest Pacific Ocean)
*[[Jameson Land]]
'''Volcanic Rifted Margins'''
*[[High Arctic Large Igneous Province]] (includes the [[Ellesmere Island Volcanics]], [[Strand Fiord Formation]], [[Alpha Ridge]], [[Franz Josef Islands]] and [[Svalbard]].)
*[[North Atlantic Igneous Province]] (includes basalts in Greenland, Iceland, Ireland, Scotland, Faroes)
*[[Central Atlantic Magmatic Province]] (eastern United States and Canada, northern South America, northwest Africa)
'''Dike Swarms'''
*[[Mackenzie dike swarm|MacKenzie Dike Swarm, Coppermine basalts]] (Canada, Precambrian)
==See also==
*[[Igneous rock]]
*[[Geologic province]]
*[[Mantle plume]]s
*[[Hotspot (geology)|Hotspots]]
*[[Oceanic plateau]]
*[[Supervolcano]]
*[[Volcanic margins]]
==References==
<div class="references-small">
<references/>
</div>
* [[Don L. Anderson|Anderson, DL]], 2005, Large igneous provinces, delammination, and fertile mantle: Elements, vol. 1, December 2005, 271-275. http://www.elementsmagazine.org/
* Baragar WRA, R.E. Ernst, L. Hulbert, T. Peterson, Longitudinal petrochemical variation in the Mackenzie dyke swarm, northwestern Canadian Shield. J. Petrol. 37: 317-359, 1996.
* Campbell, IH, 2005, Large igneous provinces and the plume hypothesis: Elements, vol. 1, December 2005, 265-269. http://www.elementsmagazine.org/
* Coffin, M.F., Eldholm, O., 1992. Volcanism and continental break-up: a global compilation of large igneous provinces. In: Storey, B.C., Alabaster, T., Pankhurst, R.J. (Eds.), Magmatism and the Causes of Continental Breakup. Special Publication. Geological Society of London, London, pp. 17-30.
* Coffin, M and Eldholm, O, 1994, Large igneous provinces: crustal structure, dimensions, and external consequences. Reviews in Geophysics, vol. 32, 1-36.
* Cohen, B., Vasconcelos, P.M.D., Knesel, K. M., 2004 ''Tertiary magmatism in Southeast Queensland'' in, ''Dynamic Earth: Past, Present and Future'', pp. 256 - 256, Geological Society of Australia
* International Association of Volcanology and Chemistry of the Earth's Interior. Large Igneous Provinces Commission. Large Igneous Provinces Record: http://largeigneousprovinces.org/record.html
* Jones, AP, 2005, Meteor impacts as triggers to large igneous provinces: Elements, vol. 1, December 2005, 277-281. http://www.elementsmagazine.org/
* Kerr, AC, 2005, Oceanic LIPS: Kiss of death: Elements, vol. 1, December 2005, 289-292. http://www.elementsmagazine.org/
* Marsh, JS, Hooper PR, Rehacek J, Duncan RA, Duncan AR, 1997. Stratigraphy and age of Karoo basalts of Lesotho and implications for correlations within the Karoo igneous province. In: Mahoney JJ and Coffin MF, editors, Large Igneous Provinces: continental, oceanic, and planetary flood volcanism, Geophysical Monograph 100, American Geophysical Union, Washington, DC, 247-272.
* Peate DW, 1997. The Parana-Etendeka Province. In: Mahoney JJ and Coffin MF, editors, Large Igneous Provinces: continental, oceanic, and planetary flood volcanism, Geophysical Monograph 100, American Geophysical Union, Washington, DC, 247-272.
* Ratajeski, K. (November 25, 2005). [http://serc.carleton.edu/research_education/cretaceous/superplume.html The Cretaceous Superplume]
* Ritsema, J., H.J. van Heijst, and J.H. Woodhouse, ''Complex shear wave velocity structure imaged beneath Africa and Iceland,'' Science, 286, 1925-1928, 1999.
* Saunders, AD, 2005, Large igneous provinces: origin and environmental consequences: Elements, vol. 1, December 2005, 259-263. http://www.elementsmagazine.org/
* Wignall, P, 2005, The link between large igneous provinces eruptions and mass extinctions: Elements, vol. 1, December 2005, 293-297. http://www.elementsmagazine.org/
* R.E. Ernst, I.H. Campbell, and K.L. Buchan, 2005, Frontiers in Large Igneous Province Research. Lithos Special Issue 79, edited by A. Kerr, R. England, and P. Wignall, p. 271-297.
==External links==
*[http://www.largeigneousprovinces.org Large Igneous Provinces Commission]
[[Category:Petrology]]
[[Category:Volcanology]]
[[Category:Flood basalts]]
[[Category:Geological hazards]]
[[Category:Supervolcanoes]]
[[Category:Large igneous provinces| ]]
[[et:Suur magmaprovints]]
[[fr:Grande province ignée]]
[[nl:Large Igneous Province]]
[[pl:duża prowincja magmatyczna]]
[[fi:Laakiopurkaus]]