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Encyclopedia > Large igneous province

Large Igneous provinces (LIPS) were originally defined by Coffin and Eldholm (1992) as areas of Earth's surface that contain very large volumes of magmatic rocks (typically basalt but including rhyolites) 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 ridges and island arcs. LIPS include continental flood basalts, oceanic plateaus, large dike swarms (the eroded roots of a volcanic province), and 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. Image File history File links This is a lossless scalable vector image. ... Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Earth cutaway from core to exosphere. ... Basalt Basalt (IPA: ) is a common gray to black extrusive volcanic rock. ... Rhyolite This page is about a volcanic rock. ... The table and timeline of geologic periods presented here is in accordance with the dates and nomenclature proposed by the International Commission on Stratigraphy. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. ... An island arc is a type of archipelago formed by plate tectonics as one oceanic tectonic plate subducts under another and produces magma. ... Moses Coulee showing multiple flood basalt flows of the Columbia River Basalt Group. ... An oceanic plateau is an undersea large igneous province, the equivalent of continental flood basalts such as the Deccan Traps in India and the Snake River Plain in the Pacific Northwest of the United States. ... Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ...


When created, LIPS often occupy a few million km² and have volumes on the order of 1 million km3. In most cases, the majority of a LIP's volume is emplaced in less than 1 million years. One of the conundrums 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.

Contents

Theories of formation

Large igneous provinces are often linked to active hotspots by linear chains of volcanic islands or volcanoes, leading to models that connect their origins to mantle plumes. 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). In geology, a hotspot is a location on the Earths surface that has experienced active volcanism for a long period of time. ... A lava lamp illustrates the basic concept of a mantle plume. ...


Alternate theories include delamination of eclogitic lower crust, edge effects of thick lithosphere, and meteorite impact (see Mantle plumes for more complete discussion of alternate models). A lava lamp illustrates the basic concept of a mantle plume. ...


Relationship to extinction events

Because a LIP may in several cases have occurred simultaneously with oceanic anoxic events and extinction events, 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 (extinction event at end of Cretaceous), the Karoo-Ferrar (extinction event at end of Toarcian), the Central Atlantic Magmatic province (extinction event at end of Triassic), and the Siberian traps (extinction event at end of Permian). Oceanic anoxic events occur when the Earths oceans become completely depleted of oxygen (O2) below the surface levels. ... An extinction event (also known as: mass extinction; extinction-level event, ELE) occurs when there is a sharp decrease in the number of species in a relatively short period of time. ...


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 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). Laki (Icelandic: Lakagígar) is a volcanic fissure situated in the south of Iceland, not far from the canyon of Eldgjá and the small town Kirkjubæjarklaustur, in Skaftafell National Park. ...


Examples of LIPs

These are well documented large igneous provinces in geological research.


Continental Flood basalts

Oceanic Plateaux Ethiopian Highlands with Ras Dashan in the background. ... The Columbia River Basalt Group encompasses portions of 3 states. ... The Deccan Traps is a large igneous province located in west-central India and is one of the largest volcanic features on Earth. ... The Paraná and Etendeka traps in Brazil, South America comprise a large igneous province which includes both the main Paraná traps as well as the smaller severed portions of the flood basalts at the Etendeka traps in Namibia and Angola. ... The Brazilian Highlands (or Planalto Brasileiro) are an extensive geographical region, covering most of the eastern, southern and central portions of Brazil, in all approximately half of the countrys land area, or some 4,000,000 km² (1,544,000 sq mi). ... The Karoo and Farrar provinces together comprise a major flood basalt province of the which is found in both South Africa and Antartica. ... The Siberian Traps (Russian: ) form a large igneous province in Siberia. ...

  • 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 The Caribbean large igneous province consists of a major flood basalt, which created this large igneous province. ... The Kerguelen Plateau is an underwater volcanic ridge—the largest in the Indian Ocean, and one of the largest in the world. ... The Ontong Java Plateau is a huge undersea plateau located in the Pacific Ocean, lying north of the Solomon Islands. ... Jameson Land is a peninsula in eastern Greenland, bounded to the southwest by Scoresby Sund (the worlds largest fjord), to the northwest by the Greenlandic mainland, and to the east by the Greenland Sea. ...

  • North Atlantic Igneous Province (includes basalts in Greenland, Iceland, Éire, Scotland, Faroes)
  • Central Atlantic Magmatic Province (eastern United States, northern South America, northwest Africa)

Dike Swarms CAMP, or the Central Atlantic Magmatic Province, was formed during the largest known volcanic event in Earth history. ...

  • MacKenzie Dike Swarm, Coppermine basalts (Canada, Precambrian)

See also

Volcanic rock on North America Plutonic rock on North America Igneous rocks form when rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... A geologic province is a spatial entity with common geologic attributes. ... A lava lamp illustrates the basic concept of a mantle plume. ... In geology, a hotspot is a location on the Earths surface that has experienced active volcanism for a long period of time. ... An oceanic plateau is an undersea large igneous province, the equivalent of continental flood basalts such as the Deccan Traps in India and the Snake River Plain in the Pacific Northwest of the United States. ... A supervolcano refers to a volcano that produces the largest and most voluminous kinds of eruption on Earth. ...

References

  • 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
  • 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). 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.

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