Share on Facebook Share on Twitter Email
Answers.com

Oceanic plateau

 
Britannica Concise Encyclopedia: oceanic plateau
Home > Library > Miscellaneous > Britannica Concise Encyclopedia

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 slopes. Some, however, occur well beyond the continental margins. They stand alone, high above the surrounding seafloor, and are believed to be fragments of continents that were isolated during continental drift and seafloor spreading.

For more information on oceanic plateau, visit Britannica.com.

Search unanswered questions...

Enter a question here...
Search: All sources Community Q&A Reference topics

Wikipedia: Oceanic plateau
Top
Home > Library > Miscellaneous > Wikipedia

An oceanic plateau (also submarine plateau) is a large, relatively flat submarine region that rises well above the level of the ambient seabed.[1] 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.

Contents

List of oceanic plateaus

Continental oceanic plateaus

Igneous oceanic plateaus

References

  1. ^ oceanic plateau. (2008). In Encyclopædia Britannica. Retrieved December 16, 2008, from Encyclopædia Britannica Online.
  2. ^ 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.

See also


This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

 
 

 

Copyrights:

Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 2006 Encyclopædia Britannica, Inc. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Oceanic plateau".  Read more