- Oceanic plateau
An oceanic plateau (also submarine plateau) is a large, relatively flat submarine region that rises well above the level of the ambient seabed. While many oceanic plateaus are composed of continental crust, and often form a step interrupting the continental slope, some plateaus are undersea remnants of large igneous provinces. These were formed by 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.
Geologists believe that igneous 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 denser than normal continental crust.
Density differences in crustal material largely arise from different ratios of various elements, especially silicon. Continental crust has the highest amount of silicon (such rock is called felsic). Oceanic crust has a smaller amount of silicon (mafic rock). Igneous oceanic plateaus have a ratio intermediate between continental and oceanic crust, although they are more mafic than felsic.
However, when a plate carrying oceanic crust subducts under a plate carrying an igneous oceanic plateau, 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, being less dense and more buoyant. If an igneous 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
Continental oceanic plateaus
Igneous oceanic plateaus
- Agulhas Plateau (Southwest Indian)
- Caribbean-Colombian Plateau (Caribbean)
- Exmouth Plateau (Indian)
- Hikurangi Plateau (Southwest Pacific)
- Kerguelen Plateau (Indian)
- Manihiki Plateau (Southwest Pacific)
- Mascarene Plateau (Indian)
- Naturaliste Plateau (Indian)
- Ontong Java Plateau (Southwest Pacific)
- Shatsky Rise (North Pacific)
- Vøring Plateau (North Atlantic)
- Wrangellia Terrane (Northeast Pacific)
- Yermak Plateau (Arctic)
- ^ oceanic plateau. (2008). In Encyclopædia Britannica. Retrieved December 16, 2008, from Encyclopædia Britannica Online.
- ^ Uenzelmann-Neben, G., K. Gohl, A. Ehrhardt, and M. Seargent (1999). Agulhas Plateau, SW Indian Ocean: New Evidence for Excessive Volcanism, Geophysical Research Letters, 26(13), 1941–1944.
Wikimedia Foundation. 2010.
Look at other dictionaries:
oceanic plateau — or submarine plateau Large submarine elevation rising sharply at least 660 ft (200 m) above the surrounding seafloor and having an extensive, relatively flat or gently tilted summit. Most plateaus are steplike interruptions of the continental… … Universalium
Oceanic trench — Oceanic crust is formed at an oceanic ridge, while the lithosphere is subducted back into the asthenosphere at trenches. The oceanic trenches are hemispheric scale long but narrow topographic depressions of the sea floor. They are also the… … Wikipedia
Plateau (disambiguation) — Plateau has several meanings:*In geology or earth science, a plateau is an area of relative low relief (i.e., relatively flat) at an important altitude, usually attributed to tectonic uplift or by sediment accumulation. If the uplift was recent,… … Wikipedia
Oceanic crust — Age of oceanic crust. The red is most recent, and blue is the oldest. Oceanic crust is the part of Earth s lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and… … Wikipedia
Oceanic basin — Diagrammatic cross section of an ocean basin, showing the various geographic features Hydrologically, an oceanic basin may be anywhere on Earth that is covered by seawater, but geologically ocean basins are large geologic basins that are below… … Wikipedia
Oceanic zone — Marine habitats The oceanic zone is the deep open ocean water that lies off the continental slopes Littoral zone Intertidal zone … Wikipedia
oceanic — /oh shee an ik/, adj. 1. of, living in, or produced by the ocean: oceanic currents. 2. of or pertaining to the region of water lying above the bathyal, abyssal, and hadal zones of the sea bottom. Cf. neritic, pelagic. 3. immensely large; vast: an … Universalium
Plateau — For other meanings, see Plateau (disambiguation). Island in the Sky, Canyonlands National Park … Wikipedia
plateau — /pla toh / or, esp. Brit., /plat oh/, n., pl. plateaus, plateaux / tohz , tohz/, v., plateaued, plateauing. n. 1. a land area having a relatively level surface considerably raised above adjoining land on at least one side, and often cut by deep… … Universalium
Ontong Java Plateau — The Ontong Java Plateau is a huge oceanic plateau located in the Pacific Ocean, lying north of the Solomon Islands. The plateau covers an area of approximately 2,000,000 km2 (770,000 sq mi), or roughly the size of Alaska, and reaches a… … Wikipedia