This is a list of submarine topographical features, oceanic landforms and topographic elements.
This is a list of submarine topographical features, oceanic landforms and topographic elements.
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 meters (9,800 ft) and 6,000 meters (20,000 ft). Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains are among the flattest, smoothest and least explored regions on Earth. [1] Abyssal plains are key geologic elements of oceanic basins (the other elements being an elevated mid-ocean ridge and flanking abyssal hills). In addition to these elements, active oceanic basins (those that are associated with a moving plate tectonic boundary) also typically include an oceanic trench and a subduction zone. Abyssal plains cover more than 33% of the ocean floor (about 23% of Earth's surface), [2] but they are poorly preserved in the sedimentary record because they tend to be consumed by the subduction process. [1] [3] [4]
The abyssal plain is formed when the lower oceanic crust is melted and forced upwards by the asthenosphere layer of the upper mantle. As this basaltic material reaches the surface at mid-ocean ridges, it forms new oceanic crust. Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited from turbidity currents that have been channeled from the continental margins along submarine canyons down into deeper water. The remainder of the sediment is composed chiefly of pelagic sediments.
Use of a continuously recording fathometer enabled Tolstoy & Ewing in the summer of 1947 to identify and describe the first abyssal plain. [1] [5] This plain, located to the south of Newfoundland, is now known as the Sohm Abyssal Plain. [5] Following this discovery many other examples were found in all the oceans. [6] [7] [8] [9] [10]
Following is a list of named abyssal plains and oceanic basins: [1] [11] [12]
Oceanic trenches are long, narrow topographic depressions of the seabed. They are the deepest parts of the ocean floor, and they define one of the most important natural boundaries on the Earth's solid surface: the one between two lithospheric plates. Trenches are a distinctive morphological feature of plate boundaries. Trenches are found in all oceans with the exception of the Arctic Ocean and they are most common in the North and South Pacific Oceans. [2]
There are three types of lithospheric plate boundaries: 1.) divergent (where lithosphere and oceanic crust is created at mid-ocean ridges), 2.) convergent (where one lithospheric plate sinks beneath another and returns to the mantle), and 3.) transform (where two lithospheric plates slide past each other).
An oceanic trench is a type of convergent boundary at which two oceanic lithospheric slabs meet; the older (and therefore denser) of these slabs flexes and subducts beneath the other slab. Oceanic lithosphere moves into trenches at a global rate of about a tenth of a square meter per second. Trenches are generally parallel to a volcanic island arc, and about 200 km from a volcanic arc. Oceanic trenches typically extend 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor. The greatest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench, at a depth of 10,911 m (35,798 ft) below sea level.
The following is a list of the deepest parts of the Earth's oceans and seas (all depths are measured from sea level):
| Name | Location | Depth (meters) | Depth (feet) | Depth (miles) | |
|---|---|---|---|---|---|
| 1 | Challenger Deep | Izu–Bonin–Mariana Arc, Mariana Trench, Pacific Ocean | 11,034 | 36,197 | 6.86 |
| 2 | Tonga Trench | Pacific Ocean | 10,882 | 35,702 | 6.76 |
| 3 | Emden Deep | Philippine Trench, Pacific Ocean | 10,545 | 34,580 | 6.54 |
| 4 | Kuril–Kamchatka Trench | Pacific Ocean | 10,542 | 34,449 | 6.52 |
| 5 | Kermadec Trench | Pacific Ocean | 10,047 | 32,963 | 6.24 |
| 6 | Izu–Ogasawara Trench | Pacific Ocean | 9,810 | 32,087 | 6.08 |
| 7 | Japan Trench | Pacific Ocean | 9,000 | 29,527 | 5.59 |
| 8 | Puerto Rico Trench | Atlantic Ocean | 8,605 | 28,232 | 5.35 |
| 9 | Yap Trench | Pacific Ocean | 8,527 | 27,976 | 5.30 |
| 10 | Richards Deep | Peru–Chile Trench, Pacific Ocean | 8,065 | 26,456 | 5.01 |
| 11 | Diamantina Deep | Diamantina fracture zone, Indian Ocean | 8,047 | 26,401 | 5.00 |
| 12 | Romanche Trench | Atlantic Ocean | 7,760 | 25,460 | 4.82 |
| 13 | Cayman Trough | Caribbean | 7,687 | 25,238 | 4.78 |
| 14 | Aleutian Trench | Pacific Ocean | 7,679 | 25,194 | 4.77 |
| 15 | Sunda Trench | Indian Ocean | 7,455 | 24,460 | 4.63 |
| 16 | Weber Deep | Banda Sea | 7,351 | 24,117 | 4.56 |
| 17 | South Sandwich Trench | Atlantic Ocean | 7,431 | 24,380 | 4.62 |
| 18 | Dordrecht Deep | Indian Ocean | 7,019 | 23,028 | 4.36 |
| 19 | Middle America Trench | Pacific Ocean | 6,669 | 21,880 | 4.14 |
| 20 | Puysegur Trench | Pacific Ocean | 6,300 | 20,700 | 3.9 |
| 21 | Vityaz Trench | Pacific Ocean | 6,150 | 20,177 | 3.8 |
| 22 | Sulu Trench | South China Sea | 5,600 | 18,400 | 3.48 |
| 23 | Litke Deep | Eurasian Basin * , Arctic Ocean | 5,450 | 17,881 | 3.39 |
| 24 | Manila Trench | South China Sea | 5,400 | 17,700 | 3.36 |
| 25 | Calypso Deep | Hellenic Trench, Mediterranean | 5,267 | 17,280 | 3.27 |
| 26 | Ryukyu Trench | Pacific Ocean | 5,212 | 17,100 | 3.24 |
| 27 | Murray Canyon * | Southern Ocean, Australia | 5,000 | 16,400 | 3.1 |
^* Entries marked are the deepest parts of their respective water bodies, but are not oceanic trenches.
An oceanic plateau is a large, relatively flat submarine region that rises well above the level of the ambient seabed. [50] 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. Continental crust has the highest amount of silicon (such rock is called felsic). Oceanic crust has a smaller amount of silicon (mafic rock).
The anomalous volcanism associated with the formation of oceanic plateaux at the time of the Cenomanian–Turonian boundary (90.4 million years) ago may have been responsible for the environmental disturbances that occurred at that time. The physical manifestations of this were elevated atmospheric and oceanic temperatures, a significant sea-level transgression, and a period of widespread anoxia, leading to the extinction of 26% of all genera. [51] These eruptions would also have resulted in the emission of large quantities of carbon dioxide into the atmosphere, leading to global warming. Additionally, the emission of sulfur monoxide, hydrogen sulfide, carbon monoxide, and halogens into the oceans would have made seawater more acidic resulting in the dissolution of carbonate, and further release of CO2. This runaway greenhouse effect was probably put into reverse by the decline of the anomalous volcanic activity and by increased CO2-driven productivity in oceanic surface waters, leading to increased organic carbon burial, black shale deposition, anoxia and mass extinction in the ocean basins. [51]
A mid-ocean ridge is a general term for an underwater mountain system that consists of various mountain ranges (chains), typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading center, which is responsible for seafloor spreading.
Plate tectonics is the scientific theory that Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of continental drift, an idea developed during the first decades of the 20th century. Plate tectonics came to be accepted by geoscientists after seafloor spreading was validated in the mid-to-late 1960s. The processes that result in plates and shape Earth's crust are called tectonics. Tectonic plates also occur in other planets and moons.
Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically 50 to 100 kilometers wide and 3 to 4 km below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about 50,000 km (31,000 mi) of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of 10,994 m (36,070 ft) below sea level.
The Mid-Atlantic Ridge is a mid-ocean ridge located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North American from the Eurasian plate and the African plate, north and south of the Azores triple junction. In the South Atlantic, it separates the African and South American plates. The ridge extends from a junction with the Gakkel Ridge northeast of Greenland southward to the Bouvet triple junction in the South Atlantic. Although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it have enough elevation to extend above sea level, for example in Iceland. The ridge has an average spreading rate of about 2.5 centimetres (1 in) per year.
A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.
The richly textured landscape of the United States is a product of the dueling forces of plate tectonics, weathering and erosion. Over the 4.5 billion-year history of the Earth, tectonic upheavals and colliding plates have raised great mountain ranges while the forces of erosion and weathering worked to tear them down. Even after many millions of years, records of Earth's great upheavals remain imprinted as textural variations and surface patterns that define distinctive landscapes or provinces.
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 and 6,000 metres. 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. They are among the flattest, smoothest, and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins.
The Taconic orogeny was a mountain building period that ended 440 million years ago (Ma) and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the east coast of the United States. As the mountain chain eroded in the Silurian and Devonian periods, sediment spread throughout the present-day Appalachians and midcontinental North America.
In hydrology, an oceanic basin (or ocean basin) is anywhere on Earth that is covered by seawater. Geologically, most of the ocean basins are large geologic basins that are below sea level.
A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about 2,600 meters (8,500 ft) and rises about 2,000 meters (6,600 ft) above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a divergent plate boundary. The rate of seafloor spreading determines the morphology of the crest of the mid-ocean ridge and its width in an ocean basin.
The Bengal Fan, also known as the Ganges Fan, is the largest submarine fan on Earth.
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.
The Franciscan Complex or Franciscan Assemblage is a geologic term for a late Mesozoic terrane of heterogeneous rocks found throughout the California Coast Ranges, and particularly on the San Francisco Peninsula. It was named by geologist Andrew Lawson, who also named the San Andreas Fault that defines the western extent of the assemblage.
An accretionary wedge or accretionary prism forms from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust, but in some cases the wedge includes the erosional products of volcanic island arcs formed on the overriding plate.
The Wrangellia Terrane is a crustal fragment (terrane) extending from the south-central part of Alaska and along the Coast of British Columbia in Canada. Some geologists contend that Wrangellia extends southward to Oregon, although this is not generally accepted.
Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and the Hebridean Terrane in northwest Scotland. During other times in its past, Laurentia has been part of larger continents and supercontinents and consists of many smaller terranes assembled on a network of early Proterozoic orogenic belts. Small microcontinents and oceanic islands collided with and sutured onto the ever-growing Laurentia, and together formed the stable Precambrian craton seen today.
The evolution of tectonophysics is closely linked to the history of the continental drift and plate tectonics hypotheses. The continental drift/ Airy-Heiskanen isostasy hypothesis had many flaws and scarce data. The fixist/ Pratt-Hayford isostasy, the contracting Earth and the expanding Earth concepts had many flaws as well.
Project FAMOUS was the first-ever marine scientific exploration by manned submersibles of a diverging tectonic plate boundary on a mid-ocean ridge. It took place between 1971 and 1974, with a multi-national team of scientists concentrating numerous underwater surveys on an area of the Mid-Atlantic Ridge about 700 kilometers west of the Azores. By deploying new methods and specialized equipment, scientists were able to look at the sea floor in far greater detail than ever before. The project succeeded in defining the main mechanisms of creation of the median rift valley on the Mid-Atlantic Ridge, and in locating and mapping the zone of oceanic crustal accretion.
Marine geophysics is the scientific discipline that employs methods of geophysics to study the world's ocean basins and continental margins, particularly the solid earth beneath the ocean. It shares objectives with marine geology, which uses sedimentological, paleontological, and geochemical methods. Marine geophysical data analyses led to the theories of seafloor spreading and plate tectonics.
The South Fiji Basin is a large 4 to 4.7 km deep oceanic basin in the south-west Pacific Ocean, south of Fiji. It was formed from the then Indo-Australian plate and is delimited to the north west by the New Hebrides Trench, and the Hunter fracture zone, to the west by the Three Kings Ridge, to the east by the Lau-Colville Ridge, and to the south by the continental shelf of Zealandia.
The Norfolk Basin, which has been subdivided into the North Norfolk Basin and South Norfolk Basin, is an ocean floor sedimentary basin between the Norfolk Ridge to the east and the Three Kings Ridge to the west, on the edge of the submerged continent of Zealandia. The northern boundary is the Cook fracture zone and the southern is the Regina ridge projecting from Northland Peninsula, New Zealand. While it has back-arc basin characteristics its formation and structure are not able to be explained by historic back-arc basin theory.
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