Oceanic plateau

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Elevation model of the ocean floor of the southern Indian Ocean with the Kerguelen Plateau , which rises with the Kerguelen to the surface of the sea.

An oceanic plateau (also ocean plateau , submarine plateau or submarine plateau ) is an extensive, relatively flat area that rises significantly (at least 200 m) above the ocean floor. As a rule, it is evidence of large magmatic events that were created by the escape of large amounts of basaltic lava on the sea floor. Their geological counterparts on the continents are magmatic large provinces (English Large Igneous Province, created by flood basalts ), such as the Dekkan Trapp in India or the basalts of the Snake River Plain in the United States .

To distinguish from the oceanic plateau in the true sense are shelf plateaus consisting abgerifteter , thinned continental crust are made. These include Zealandia or the Rockall Plateau.

meaning

Since oceanic plateaus have a lower density than the surrounding ocean floor, they could represent a transition stage to continental crust. The differences in density arise from the different proportions of the various minerals that are involved in the structure of the rocks . On average, the continental crust has the highest proportion of felsic (feldsdpat and quartz-rich) rocks, while the oceanic crust consists to a significantly greater extent of mafic rocks . The rocks of oceanic plateaus are more rocky than normal oceanic crust, but even more mafic than continental crust.

In the event of a collision of an oceanic plate with an oceanic plateau, a significant part of the oceanic plateau may not be subducted, but rather welded to the continental plate. So-called accretion occurs . They could therefore play an important role in the currently assumed growth of continents.

List of ocean plateaus

See also

literature

  • Rajeev K. Nair and Thomas Chacko: Oceanic Plateaus: Nuclei for Archean Cratons . 2005 ( online abstract ).

Individual evidence

  1. ^ Oceanic Plateau. In: Encyclopædia Britannica. 2008, accessed January 28, 2010 .
  2. ↑ G. Uenzelmann-Neben, K. Gohl, A. Ehrhardt and M. Seargent: Agulhas Plateau, SW Indian Ocean: New Evidence for Excessive Volcanism . In: Geophysical Research Letters . tape 26 (13) , 1999, pp. 1941–1944 ( online abstract ).