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Encyclopedia > Oceanic plateau

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. An oceanic plateau, as its name suggests, rises above the level of the ambient seabed. A large igneous province (LIP) is an extensive region of basalts resulting from flood basalt volcanism. ... A flood basalt is a giant volcanic eruption that coats large stretches of land with basalt lava. ... The Deccan Traps is a large igneous province located in west-central India and is one of the largest volcanic features on Earth. ... Big Southern Butte The Snake River Plain is a geological feature of (primarily) the American state of Idaho. ... Darker red states are always considered part of the Pacific Northwest. ...


Geologists believe that oceanic plateaus may well represent a stage in the development of continental crust as they are generally less dense than oceanic crust while still being more dense than normal continental crust. The continental crust is the layer of granitic, sedimentary and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. ... Age of oceanic crust Oceanic crust is the part of Earths lithosphere which underlies the ocean basins. ...


Density differences in crustal material largely arise from different ratios of various elements, especially silicon. Continental crust has the highest amount of silicon and is called "felsic". Oceanic crust has a smaller amount and is called "mafic". Oceanic plateaus have a ratio intermediate between continental and oceanic crust, although they are more mafic than felsic. General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ... Felsic is a term used in geology to refer to silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silica, oxygen, aluminium, sodium, and potassium. ... In geology, mafic minerals and rocks are silicate minerals, magmas, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier elements. ...


However, when a plate carrying an oceanic plateau subducts a plate carrying oceanic crust, the volcanism which erupts on the plateau as the oceanic crust heats up on its descent into the mantle erupts material which is more felsic than the material which makes up the plateau. This represents a step toward creating crust which is increasingly continental in character, less dense and more buoyant. If an oceanic plateau is subducted underneath another one, or under existing continental crust, the eruptions produced thereby produce material that is yet more felsic, and so on through geologic time.


List of Oceanic Plateaus

Kerguelen Plateau (Indian Ocean) The Kerguelen Plateau is an underwater volcanic ridge—the largest in the Indian Ocean, and one of the largest in the world. ...


Ontong Java Plateau (South Pacific)


Caribbean-Colombian Plateau (Caribbean)


Central Atlantic Magmatic Province (North Atlantic) CAMP, or the Central Atlantic Magmatic Province, was formed during the largest known volcanic event in Earth history. ...


Shatsky Rise (North Pacific)


Agulhas Plateau (South Atlantic)


References

  • Oceanic Plateaus: Nuclei for Archean Cratons

 
 

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