An oceanic or submarine plateau is a large, relatively flat elevation that is higher than the surrounding relief with one or more relatively steep sides.
There are 184 oceanic plateaus in the world, covering an area of or about 5.11% of the oceans. The South Pacific region around Australia and New Zealand contains the greatest number of oceanic plateaus (see map).
Oceanic plateaus produced by
large igneous province
A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation ...
s are often associated with
hotspots
Hotspot, Hot Spot or Hot spot may refer to:
Places
* Hot Spot, Kentucky, a community in the United States
Arts, entertainment, and media Fictional entities
* Hot Spot (comics), a name for the DC Comics character Isaiah Crockett
* Hot Spot (Tr ...
,
mantle plume
A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...
s, and
volcanic islands
Geologically, a high island or volcanic island is an island of volcanic origin. The term can be used to distinguish such islands from low islands, which are formed from sedimentation or the uplifting of coral reefs (which have often formed ...
— such as Iceland, Hawaii, Cape Verde, and Kerguelen. The three largest plateaus, the
Caribbean,
Ontong Java, and
Mid-Pacific Mountains
The Mid-Pacific Mountains (MPM) is a large oceanic plateau located in the central North Pacific Ocean or south of the Hawaiian–Emperor seamount chain. Of volcanic origin and Mesozoic in age, it is located on the oldest part of the Pacific Pla ...
, are located on
thermal swells. Other oceanic plateaus, however, are made of rifted continental crust, for example the
Falkland Plateau,
Lord Howe Rise, and parts of
Kerguelen
The Kerguelen Islands ( or ; in French commonly ' but officially ', ), also known as the Desolation Islands (' in French), are a group of islands in the sub-Antarctic constituting one of the two exposed parts of the Kerguelen Plateau, a large ...
,
Seychelles
Seychelles (, ; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic state consisting of 115 islands in the Indian Ocean. Its capital and largest city, ...
, and Arctic ridges.
Plateaus formed by large igneous provinces were formed by the equivalent of continental
flood basalt
A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reac ...
s such as the
Deccan Traps in India and the
Snake River Plain in the United States.
In contrast to continental flood basalts, most igneous oceanic plateaus erupt through young and thin ()
mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks incl ...
or
ultra-mafic crust and are therefore uncontaminated by felsic crust and representative for their mantle sources.
These plateaus often rise above the surrounding ocean floor and are more buoyant than oceanic crust. They therefore tend to withstand subduction, more-so when thick and when reaching subduction zones shortly after their formations. As a consequence, they tend to "dock" to continental margins and be preserved as
accreted terrane
In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust (geology), crust fragment formed on a tectonic plate (or broken off from it) and Accretion (geology), accreted or "Suture (geology), sutured" to crust lying on another pla ...
s. Such terranes are often better preserved than the exposed parts of continental flood basalts and are therefore a better record of large-scale volcanic eruptions throughout Earth's history. This "docking" also means that oceanic plateaus are important contributors to the growth of continental crust. Their formations often had a dramatic impact on global climate, such as the most recent plateaus formed, the three, large, Cretaceous oceanic plateaus in the Pacific and Indian Ocean: Ontong Java, Kerguelen, and Caribbean.
Role in crust–mantle recycling
Geologists believe that igneous oceanic plateaus may well represent a stage in the development of
continental crust
Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called '' sial'' be ...
as they are generally less dense than
oceanic crust
Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic ...
while still being denser than normal continental crust.
Density differences in crustal material largely arise from different ratios of various elements, especially
silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ta ...
. Continental crust has the highest amount of silicon (such rock is called
felsic). Oceanic crust has a smaller amount of silicon (
mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks incl ...
rock). Igneous oceanic plateaus have a ratio intermediate between continental and oceanic crust, although they are more mafic than felsic.
However, when a
plate
Plate may refer to:
Cooking
* Plate (dishware), a broad, mainly flat vessel commonly used to serve food
* Plates, tableware, dishes or dishware used for setting a table, serving food and dining
* Plate, the content of such a plate (for example: ...
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
*
Campbell Plateau
The Campbell Plateau is a large oceanic plateau south of New Zealand and the Chatham Rise. It originated in the Gondwanan breakup and is part of Zealandia, a largely submerged continent. The above sea level parts of the plateau — the Bounty ...
(South Pacific)
*
Challenger Plateau
The Challenger Plateau is a large submarine plateau west of New Zealand and south of the Lord Howe Rise. It has an approximate diameter of and an area of about . The water depth over the plateau varies between to and is covered by up to of s ...
(South Pacific)
*
Exmouth Plateau
The Exmouth Plateau is an elongate northeast striking extensional passive margin located in the Indian Ocean roughly 3,000 meters offshore from western and northwestern Western Australia.
The plateau makes up the westernmost structural unit of t ...
(Indian)
*
Falkland Plateau (South Atlantic)
*
Lord Howe Rise (South Pacific)
*
Rockall Plateau
The Rockall Trough ( gd, Clais Sgeir Rocail) is a deep-water bathymetric feature to the northwest of Scotland and Ireland, running roughly from southwest to northeast, flanked on the north by the Rockall Plateau and to the south by the Porcu ...
(North Atlantic)
Igneous oceanic plateaus
*
Agulhas Plateau
The Agulhas Plateau is an oceanic plateau located in the south-western Indian Ocean about south of South Africa. It is a remainder of a large igneous province (LIP), the Southeast African LIP, that formed (Ma) at or near the triple junction wher ...
(Southwest Indian)
*
Azores Plateau (North Atlantic)
*
Broken Plateau (Indian)
*
Caribbean-Colombian Plateau (Caribbean)
*
Exmouth Plateau
The Exmouth Plateau is an elongate northeast striking extensional passive margin located in the Indian Ocean roughly 3,000 meters offshore from western and northwestern Western Australia.
The plateau makes up the westernmost structural unit of t ...
(Indian)
*
Hikurangi Plateau
The Hikurangi Plateau is an oceanic plateau in the South Pacific Ocean east of the North Island of New Zealand. It is part of a large igneous province (LIP) together with Manihiki and Ontong Java, now located and north of Hikurangi respective ...
(Southwest Pacific)
*
Iceland Plateau
The Iceland Plateau or Icelandic Plateau is an oceanic plateau in the North Atlantic Ocean consisting of Iceland and its contiguous shelf and marginal slopes. The landscape is constantly experiencing deformation due to the continual addition of ma ...
(North Atlantic)
*
Kerguelen Plateau
The Kerguelen Plateau (, ), also known as the Kerguelen–Heard Plateau, is an oceanic plateau and a large igneous province (LIP) located on the Antarctic Plate, in the southern Indian Ocean. It is about to the southwest of Australia and is ...
(Indian)
*
Magellan Rise (Pacific)
*
Manihiki Plateau
The Manihiki Plateau is an oceanic plateau in the south-west Pacific Ocean. The Manihiki Plateau was formed by volcanic activity 125 to 120 million years ago during the mid- Cretaceous period at a triple junction plate boundary called the Tongarev ...
(Southwest Pacific)
*
Mascarene Plateau
The Mascarene Plateau is a submarine plateau in the Indian Ocean, north and east of Madagascar. The plateau extends approximately , from Seychelles in the north to Réunion in the south. The plateau covers an area of over of shallow water, wi ...
(Indian)
*
Naturaliste Plateau
The Naturaliste Plateau is one of several large submarine plateaus extending from Western Australia into the Indian Ocean. It is a rectilinear plateau that covers an area of 90,000 square kilometres. Its width is about east-west and north-so ...
(Indian)
*
Ontong Java Plateau
The Ontong Java Plateau (OJP) is a massive oceanic plateau located in the southwestern Pacific Ocean, north of the Solomon Islands.
The OJP was formed around (Ma) with a much smaller volcanic event around 90 Ma. Two other southwestern Pacific ...
(Southwest Pacific)
*
Shatsky Rise
The Shatsky Rise is Earth's third largest oceanic plateau, (after Ontong Java and Kerguelen) located in the north-west Pacific Ocean east of Japan. It is one of a series of Pacific Cretaceous large igneous provinces (LIPs) together with Hess R ...
(North Pacific)
*
Vøring Plateau (North Atlantic)
*
Wrangellia Terrane (Northeast Pacific)
*
Yermak Plateau
Yermak Timofeyevich ( rus, Ерма́к Тимофе́евич, p=jɪˈrmak tʲɪmɐˈfʲejɪvʲɪtɕ; born between 1532 and 1542 – August 5 or 6, 1585) was a Cossack ataman and is today a hero in Russian folklore and myths. During the reign ...
(Arctic)
See also
*
Abyssal plain
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between and . Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. ...
*
Bathymetry
Bathymetry (; ) is the study of underwater depth of ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water ...
*
Glossary of landforms
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
Landforms by process
Landforms organized by the processes that create them.
Aeoli ...
*
Ocean bank
References
Notes
Sources
*
*
* (updated February 2017)
*
*
*
External links
Gsa.confex.com: "Oceanic Plateaus: Nuclei for Archean Cratons"Tristan.ferroir.free.fr: "On the oceanic plateaux"
{{Tectonic plates
01
Coastal and oceanic landforms
Submarine topography
Physical oceanography
Plate tectonics
Oceanographical terminology
Abyssal plains
Aquatic ecology