Deep water trench
Deep-sea trench
(ocean trench), a narrow, closed and deep trough of the ocean floor. Length from several hundred to 4000 km. Trenches are located along the margins of continents and the oceanic side of island arcs. Deep varies, from 5500 to 11 thousand m. They occupy less than 2% of the bottom area of the World Ocean. There are 40 known deep-sea trenches (30 in Pacific Ocean and 5 trenches in the Atlantic and Indian oceans). Along the periphery of the Pacific Ocean they form an almost continuous chain. The deepest are in the west. parts of it. These include: Mariana Trench, Philippine Trench, Kuril-Kamchatka Trench, Izu-Ogasawara, Tonga, Kermadec, New Hebrides Trench. The transverse profiles of the bottom of deep-sea trenches are asymmetrical, with a higher, steeper and dissected continental or island slope and a relatively low oceanic slope, which is sometimes bordered by an outer shaft of relatively low height. The bottom of the gutters is usually narrow, with a number of flat-bottomed depressions visible on it.
Trenches are part of the transition zone from continent to ocean, within which the type of earth's crust changes from continental to oceanic. The trenches are associated with high seismic activity, expressed in both surface and deep earthquakes. Deep-sea trenches were discovered in the last quarter of the 19th century. when laying transoceanic telegraph cables. A detailed study of the trenches began using echo sounder depth measurements.
Geography. Modern illustrated encyclopedia. - M.: Rosman. Edited by prof. A. P. Gorkina. 2006 .
See what a “deep-sea trench” is in other dictionaries:
Diagram of an oceanic trench A trench (ocean trench) is a deep and long depression on the ocean floor (5000-7000 m or more). Formed by pressing oceanic crust under another oceanic or continental crust (plate convergence).... ... Wikipedia
See deep-sea trench. Geography. Modern illustrated encyclopedia. M.: Rosman. Edited by prof. A. P. Gorkina. 2006 ... Geographical encyclopedia
The Philippine Trench is a deep-sea trench located east of the Philippine Islands. Its length is 1320 km, from the northern part of Luzon to the Molluc Islands. Deepest point 10540 m. Philippine... ... Wikipedia
A deep-sea trench in the western Pacific Ocean, east and south of the Mariana Islands. Length 1340 km, depth up to 11022 m (maximum depth of the World Ocean). * * * MARIANA THANGE MARIANA Trench, a deep-sea trench in the western part... ... encyclopedic Dictionary
An ocean trench is a long, narrow depression on the ocean floor, hidden deep underwater. These dark, mystical recesses can be found at depths of up to 10,994 meters. By comparison, if Mount Everest were placed at the bottom of its deepest depression, its summit would be approximately 2.1 kilometers below the surface of the water.
Formation of ocean trenches
Ocean trench
The world has many tall volcanoes and mountains, but deep oceanic trenches dwarf any of the continental highlands. How are these depressions formed? The short answer comes from geology and the study of tectonic plate movements, which relate to earthquakes as well as volcanic activity.
Scientists have discovered that deep blocks of the earth's crust are moving on the surface of the Earth's mantle. Typically, oceanic crust is subducted beneath island arcs or continental margins. The boundary where they meet is in places that are deep ocean trenches. For example, the Mariana Trench, located on the floor of the Pacific Ocean, next to the Mariana island arc, off the coast of Japan, is the result of what is called “subduction.” The Mariana Trench formed at the junction of the Eurasian and Philippine plates.
Gutter location
Ocean trenches exist throughout the world and are typically the deepest areas. These include: the Philippine Trench, Tonga Trench, South Sandwich Trench, Puerto Rico Trench, Peruvian-Chilean Trench, etc.
Many (but not all) are directly related to subduction. Interestingly, the Diamantina Trench was formed about 40 million years ago, when it was demarcated. Most of the deepest ocean trenches known are found in the Pacific Ocean.
The deepest point of the Mariana Trench is called the Challenger Deep, and it lies at a depth of almost 11 km. However, not all ocean trenches are as deep as the Mariana Trench. Gutters can fill up with age bottom sediments(sand, rocks, mud and dead organisms that settle to the ocean floor).
Exploring Ocean Trenches
Most gutters were not known until the late 20th century. Studying them requires specialized underwater vehicles, which did not exist until the second half of the 1900s.
Bathyscaphe "Trieste"
These deep ocean trenches are unsuitable for life for most living organisms. The water pressure at these depths would kill a person instantly, which is why no one dared to explore the bottom of the Mariana Trench for many years. However, in 1960, two researchers dived into the Challenger Deep using a bathyscaphe called Trieste. And only in 2012 (52 years later) another person dared to conquer the deepest point of the World Ocean. It was the film director (known for the films “Titanic”, “Avatar”, etc.) and underwater explorer James Cameron, who made a solo dive using the Deepsea Challenger bathyscaphe and reached the bottom in the Challenger Basin of the Mariana Trench. Most other deep-sea research vehicles, such as Alvin (used by the Woods Hole Oceanographic Institution in Massachusetts), have not dived to great depths so far, but can still go down to about 3,600 meters.
Is there life in deep sea trenches?
Surprisingly, despite high pressure water and cold temperatures that exist at the bottom of deep sea trenches, life thrives in these extreme conditions.
Tiny single-celled organisms live at great depths, as do some species of fish (including), tube worms and sea cucumbers.
Future exploration of the deep sea
Exploring the deep sea is expensive and complex, although the scientific and economic rewards can be significant. Human exploration (like Cameron's deep sea dive) is dangerous. Future exploration may well rely (at least in part) on automated drones, just as astronomers use them to study distant planets. There are many reasons to continue exploring the deep ocean; they remain the least studied terrestrial environments. Further research will help scientists understand the workings of plate tectonics, as well as identify new life forms that have adapted to some of the most inhospitable habitats on the planet.
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An amazingly perfect creation - man! He can not only see, hear, feel what is next to him or around him, but also mentally imagine what he has never seen. He can dream, he can imagine. Let us imagine the oceans and seas... without water, and for this we will look at the physical-geographical map of the ocean floor. We will see that at the bottom along the edges of the oceans there are long and very deep slit-like depressions. This - deep sea trenches. Their length reaches thousands of kilometers, and the bottom is three to six kilometers deeper than the bottom of the adjacent parts of the ocean.
Deep-sea trenches are not found everywhere. They are common near the mountainous edges of continents or along island arcs. Many of you probably know the Kuril-Kamchatka, Philippine, Peruvian, Chilean and other trenches in the Pacific Ocean, the Puerto Rican and South Sandwich trenches in the Atlantic. Deep-sea trenches border the Pacific Ocean on many sides. But there are few of them in Indian Ocean. They are almost completely absent along the periphery Atlantic Ocean and are completely absent in the Arctic basin. What's the matter?
Trenches are the deepest depressions on our planet. They are most often located near high mountain ranges of land. So mountain ranges on land or along the edges of the oceans and deep-sea trenches are actually adjacent to each other. We remind the reader that the highest point on Earth ( Mount Everest or Chomolungma) has a height of 8844 meters ( according to some sources 8882 meters), and the bottom of the deepest Mariana Trench is at a depth of 11,022 meters. The difference is 19866 meters! The vibration of the surface of our planet has such an almost twenty-kilometer range.
However, Chomolungma is several thousand kilometers away from the Mariana Trench. But at Mount Llullaillaco ( 6723 meters) in the Cordillera and the nearby Chilean Trench ( 8069 meters) the difference is 14792 meters. This is perhaps the most dramatic contrast of heights and depths on Earth.
During geological development, mountains rise up - the trenches deepen, the mountains are destroyed - the trenches are filled with sediment. Thus, mountain ranges and deep-sea trenches represent a single system. These are the “Siamese twins” of geology.
But the nature of the formation of these geological twins is a mystery of mysteries. Scientists cannot find a single answer to this to this day. It was assumed that in the places of the trenches the earth's crust, under the influence of some unknown forces, bends. Scientists then began to believe that the gutters formed at the site of deep cracks. Subsequently, scientists learned that trenches are formed where two lithospheric plates move against each other. Having collided, one of them “wins” - it crawls onto the other. But they continue their movement even after the collision, and at a fairly fast, from a geological point of view, speed - about 5 - 10 centimeters per year. Such rapid movement does not allow the edges of the slabs to wrinkle into folds. Therefore, one of the plates must give way to the other. The “winner” in the struggle between these two geological giants turns out to be the continental plate: it “crawls” onto the thinner oceanic crust, crushing it under itself. The “defeated” oceanic plate goes into the softened and highly heated mantle - into the asthenosphere. There it heats up greatly and again turns into a semi-molten substance - magma. According to the calculations of the Soviet scientist O. G. Sorokhotin, about 50 billion tons of oceanic crust matter sinks into the trenches under the continental plates per year. Consequently, the subsoil “devours” and melts down almost as much oceanic crust per year as it grows in the rift valleys of mid-ocean ridges.
The area where one plate is being pushed under another is called the underthrust zone. The oceanic plate there bends strongly downward. In the place of such a bend, deep and narrow depressions are formed - deep-sea trenches.
Many of you, dear readers, studying geographic Maps, noticed that island arcs and deep-sea trenches on maps have a horseshoe shape. You will ask why? Imagine that you are cutting an apple with a knife. We made a small incision and... stop! Take out the knife. Look at the cut above. It has the shape of a semicircle. The earth is round. The plates also have the shape of hemispheres. When one plate rises onto another, the place where they collide and move occurs along a plane directed, like the plane of a knife when cutting an apple, not perpendicular to the surface of the sphere ( Earth), but at some angle. This causes the formation of arc-shaped grooves. This form is very clearly visible if you look at the Kuril-Kamchatka region and the Aleutian Islands.
The continental crust advancing onto the oceanic plate cracks in areas of underthrust. Semi-molten substance - magma - rises into cracks from the depths of the Earth under the influence of enormous compression forces. Numerous volcanoes and volcanic mountains form along the edges of the cracked continental plate, often arranged in a long chain. This is how individual mountains or island arcs and mountain ranges with numerous active and extinct volcanoes are formed. These are the Aleutian, Kuril, Lesser Antilles and other islands, mountain ranges - the Cordillera and others. Such mountain ranges and island arcs with volcanoes surrounding oceans are called “rings of fire.”
Deep Sea Depressions- These are predominantly long (they stretch for hundreds and thousands of kilometers) and narrow (only tens of kilometers) troughs of the ocean floor with depths of more than 6000 m, which are located near the steep underwater slopes of continents and island chains. They are probably the most characteristic element of the bottom of the World Ocean.
Recently, the term "" is increasingly being replaced by the term " deep sea trench”, which more accurately conveys exactly the shape of depressions of this kind. Deep ocean trenches are among the most typical elements of the relief of the transition zone between the continent and the ocean.
Deep-sea trenches have the greatest depth in the entire oceans. According to Russian studies, the depth of such trenches can reach 11 km or more; this means that the trenches are twice as deep as the ocean floor in deep-sea basins. The gutters have steep, sheer slopes and an almost flat bottom. Geologically, deep sea trenches are modern geologically active structures. Currently, 20 such gutters are known. They are located on the periphery of the oceans, there are more of them in the Pacific Ocean (16 trenches are known), three in the Atlantic and one in the Indian Ocean. The most significant depressions, more than 10,000 m deep, are located in the Pacific Ocean - this is the oldest ocean on Earth.
They are usually parallel to the surrounding island arcs and young coastal mountain formations. Deep-sea trenches have a sharply asymmetrical transverse profile. On the ocean side they are adjacent to a deep-sea plain, on the opposite side - an island ridge or a high mountain range.
In some places, the tops of the mountains rise relative to the bottom of the trenches by 17 km, which is a record among terrestrial values.
All deep-sea depressions and trenches have oceanic crust. The trench is formed as a result of the pressing of oceanic crust when it goes under another oceanic or continental crust. Plates of the lithosphere usually have crust of different origins, sometimes it is continental crust, sometimes it is crust of oceanic origin. Due to the difference in the type of crust, different processes occur along their boundaries as the plates approach each other. When a plate with continental crust approaches a plate covered with oceanic crust, the lithospheric plate with continental crust always moves onto the plate with oceanic crust and crushes it under itself.
The oceanic plate bends and seems to “dive” under the continental plate, while the edge of the oceanic plate, plunging into the mantle, forms a deep-sea trench in the ocean along the coast. The opposite edge of the oceanic plate rises - island arcs form there. On land, mountains rise along the coast. For this reason, trench areas are often the epicenters of earthquakes, and the bottom is the base of many volcanoes. This happens because the trenches are adjacent to the edges of the lithospheric plates. Most scientists believe that deep-sea trenches are marginal troughs where intensive accumulation of sediments from destroyed rocks takes place.
The most typical example of such interaction between plates and crust is of various origins is the development of the Peru-Chile Trench in the Pacific Ocean off the coast South America and the Andes mountain range systems on the west coast of that continent. This development occurs because the American plate of the lithosphere is slowly moving towards the Pacific plate, crushing it under itself.
Magma, which mainly makes up top part mantle, translated from Greek language literally means "thick ointment".
Another type is transverse, or branch, gutters. They cross ocean ridges, plateaus and continental structures. These gutters are symmetrically built and rectilinear, have a transverse or diagonal structure. Sometimes they are lined up like scenes. There is usually no island near the front of these gutters. They are associated with faults that cross mid-ocean ridges.
Parallel to the deep-sea trenches there are intermediate depressions, near which there are twin island arcs or submerged ridges. The intermediate basin is always located between the inner volcanic and outer non-volcanic island arcs. Such depressions are never as deep as the neighboring trench.
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Deep sea trenches. These are relatively narrow depressions with steep, sheer slopes, stretching for hundreds and thousands of kilometers. The depth of such depressions is very great. Deep-sea trenches have an almost flat bottom. These are where the greatest depths of the oceans are located. Typically, trenches are located on the oceanic side of the arcs, repeating their bend, or stretch along the continents. Deep-sea trenches are a transition zone between the continent and the ocean.
The formation of gutters is associated with movement. The oceanic plate bends and seems to “dive” under the continental plate. In this case, the edge of the oceanic plate, plunging into the mantle, forms a trench. The areas of deep-sea trenches are in the zones of manifestation and high. This is explained by the fact that the trenches are adjacent to the edges of the lithospheric plates.
According to most scientists, deep-sea trenches are considered marginal troughs and it is there that intensive accumulation of sediments takes place.
The deepest on Earth - Mariana Trench. Its depth reaches 11,022 m. It was discovered in the 50s by an expedition on the Soviet research vessel Vityaz. The research of this expedition was very great importance to study gutters.
Deep sea trenches of the Earth
| Gutter name | Depth, m | Ocean |
|---|---|---|
| Mariana Trench | 11022 | Quiet |
| () | 10882 | Quiet |
| Philippine Trench | 10265 | Quiet |
| Kermadec (Oceania) | 10047 | Quiet |
| Izu-Ogasawara | 9810 | Quiet |
| Kuril-Kamchatka Trench | 9783 | Quiet |
| Puerto Rico Trench | 8742 | |
| Japanese gutter | 8412 | Quiet |
| South Sandwich Trench | 8264 | Atlantic |
| Chilean Trench | 8180 | Quiet |
| Aleutian Trench | 7855 | Quiet |
| Sunda Trench | 7729 | Indian |
| Central American Trench | 6639 | Quiet |
| Peruvian Trench | 6601 | Quiet |