Oceanic basin

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 sea level. Geologically, there are other undersea geomorphological features such as the continental shelves, the deep ocean trenches, and the undersea mountain ranges (for example, the mid-Atlantic ridge) which are not considered to be part of the ocean basins; while hydrologically, oceanic basins include the flanking continental shelves and shallow, epeiric seas.

Some consider the oceanic basins to be the complement to the continents, with erosion dominating the latter, and the sediments so derived ending up in the ocean basins. Others regard the ocean basins more as basaltic plains, than as sedimentary depositories, since most sedimentation occurs on the continental shelves and not in the geologically-defined ocean basins.

Hydrologically some geologic basins are both above and below sea level, such as the Maracaibo Basin in Venezuela, although geologically it is not considered an oceanic basin because it is on the continental shelf and underlain by continental crust.

Earth is the only planet with bimodal hypsography, reflecting the different kinds of crust, oceanic crust and continental crust. Oceans cover 70% of the Earth's surface. Because oceans lie lower than continents, the former serve as sedimentary basins that collect sediment eroded from the continents, known as clastic sediments, as well as precipitation sediments. Ocean basins also serve as repositories for the skeletons of carbonate- and silica-secreting organisms such as coral reefs, diatoms, radiolarians, and foraminifera.

Geologically, oceanic basins may be actively changing size or may be inactive, depending on whether there is a moving plate tectonic boundary associated with it. The elements of an active - and growing - oceanic basin include an elevated mid-ocean ridge, flanking abyssal hills leading down to abyssal plains. The elements of an active oceanic basin often include the oceanic trench associated with a subduction zone.

The Atlantic ocean and the Arctic ocean are good examples of active, growing oceanic basins, whereas the Mediterranean Sea is shrinking. The Pacific Ocean is also an active, shrinking oceanic basin, even though it has both spreading ridge and oceanic trenches. Perhaps the best example of an inactive oceanic basin is the Gulf of Mexico, which formed in Jurassic times and has been doing nothing but collecting sediments since then. The Sea of Japan and Bering Sea are also good examples of inactive oceanic basins.

See also

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • 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

  • Basin — may mean:* Drainage basin, hydrological basin or catchment basin, a region of land where water drains downhill into a specified body of water * Tarim Basin, located in Xinjiang, China and is one of the largest drainage basins in the world. *… …   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 plateau — 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… …   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 ridge — Continuous, submarine mountain chain extending approximately 50,000 mi (80,000 km) through all the world s oceans, separating them into distinct basins. The main ridge extends down the middle of the Atlantic Ocean, passes between Africa and… …   Universalium

  • List of Oceanic basins — The following is a list of oceanic basins:*Aleutian Basin *Agulhus Basin *Amerasian Basin, Arctic Ocean *Angola Basin *Arabian Basin *Argentine Basin *Bauer Basin *Blake Basin, Atlantic Ocean *Brazil Basin * Canada Basin, Arctic Ocean *Canary… …   Wikipedia

  • North Polar Basin — For the region on Mars, see North Polar Basin (Mars). The North Polar Basin is an oceanic basin in the Arctic Ocean, consisting of two main parts, the Amerasian Basin (also Central Polar Basin) and the Eurasian Basin (also Norwegian Basin), which …   Wikipedia

  • Tsushima Basin — Infobox East Asian title=Tsushima Basin caption=Tsushima Basin where the Sea of Japan meets the Korea Strait sort=japanese2 kanji=対馬海盆 hiragana=つしまかいぼん hepburn=Tsushima Kaibon japanesetext=Lang en|Tsushima Basin koreanname=South Korean name… …   Wikipedia

  • Cape Verde Basin — ▪ basin, Atlantic Ocean Portuguese  Bacia Do Cabo Verde,         submarine depression in the Atlantic Ocean that rises to meet the submerged Mid Atlantic Ocean Ridge to the west and the western African coast to the east. With the contiguous… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.