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 | Galathea Depth | 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 | Java 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 about 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.
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 10,920 m (35,830 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.
In marine geology, a guyot, also called a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than 200 m (660 ft) below the surface of the sea. The diameters of these flat summits can exceed 10 km (6.2 mi). Guyots are most commonly found in the Pacific Ocean, but they have been identified in all the oceans except the Arctic Ocean. They are analogous to tables on land.
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.
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 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, sediments from the mountain chain 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.
The Bengal Fan, also known as the Ganges Fan, is the largest submarine fan on Earth.
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.
A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from tensional forces, caused by a process known as oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics.
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.
The Leech River Fault extends across the southern tip of Vancouver Island in British Columbia, Canada, creating the distinctively straight, narrow, and steep-sided valley, occupied by Loss Creek and two reservoirs, that runs from Sombrio Point due east to the Leech River, and then turns southeast to run past Victoria. It is a thrust fault that marks the northernmost exposure of the Crescent Terrane, where basalt of the Metchosin Igneous Complex is dragged under Vancouver Island by the subducting Juan de Fuca Plate. About ten kilometers north the nearly parallel San Juan Fault marks the southern limit of rock of the Wrangellia terrane, which underlies most of Vancouver Island. Between these two northeast-dipping thrust faults are the Leech River Complex and the Pandora Peak Unit. These, along with the Pacific Rim Complex further up the coast, are remnants of the Pacific Rim Terrane which was crushed between Wrangellia and Siletzia. The contact between the bottom of Wrangellia and the top of the subducted PRT continues northwest along the coast as the West Coast Fault, and southeast towards Victoria as the Survey Mountain Fault. The Leach River Fault (LRF) extends off-shore towards Cape Flattery, where the Crescent—Pacific Rim contact continues northwest as the Tofino Fault (TF).
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.
The plate theory is a model of volcanism that attributes all volcanic activity on Earth, even that which appears superficially to be anomalous, to the operation of plate tectonics. According to the plate theory, the principal cause of volcanism is extension of the lithosphere. Extension of the lithosphere is a function of the lithospheric stress field. The global distribution of volcanic activity at a given time reflects the contemporaneous lithospheric stress field, and changes in the spatial and temporal distribution of volcanoes reflect changes in the stress field. The main factors governing the evolution of the stress field are:
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 East Luzon Trough is an oceanic trench north of the Philippine Trench and east of the island of Luzon. The trench is located near the Philippine orogeny and located in the southeastern region of the Philippine Sea Plate. The depth of the trough is 5,700 meters. The East Luzon Trough formed during the Eocene and Oligocene epoch, 40–24 million years ago.
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.
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