The lithospheric plate is continental. Plate tectonics. The process of formation of lithospheric plates
Geography - region scientific research, which solve the problems of the relationship between the peculiarities of nature with the surface of the Earth and human life.
The lithosphere is the hard shell of the Earth, which affects the formation of the surface relief. The structure of the lithosphere is formed by the earth's crust and the upper movable layer of the mantle. The formation of the earth's surface occurs due to lithospheric blocks.
Rice. 1. Lithosphere in geography
Lithospheric plates are huge and stable areas of the Earth's crust. These blocks lie on the movable upper layer of the mantle - a molten layer of igneous rocks. Therefore, the blocks are in constant horizontal motion. The plates are displaced relative to each other. The movement speed reaches 5 - 18 cm per year.
Rice. 2. Lithospheric plates in geography. What parts are the plates of the lithosphere made of?
There are two types of the earth's crust: continental - continents or continents, oceanic - under the thickness of the oceans. The lithospheric plate can be, for example, only oceanic - this is the Pacific plate. Others are composed of continental and oceanic. The thickness of the earth's crust reaches 150 - 350 km. - mainland, and 5 - 90 km. - oceanic. The displacement of lithospheric platforms leads to their tectonic impact on each other, the dynamics and structure of the earth's surface depend on this.
Rice. 3. Components of the lithosphere. Lithospheric plates on the map and their names.
Rice. 4. Names of lithospheric plates on the World Map. The main list of lithospheric plates is made up of huge blocks with an area of more than 20 million km². A significant part of the continental mass is concentrated on these blocks and the waters of the World Ocean are concentrated.
- Pacific plate - oceanic tectonic plate under the Pacific Ocean - 103.300.000 km²;
- North American tectonic platform, includes the continents: North America, the eastern part of Eurasia and the island of Greenland - with an area of 75.900.000 km²;
- Eurasian platform - tectonic block, includes part of the continent Eurasia - 67.800.000 km²;
- African- lies at the heart of Africa - 61.300.000 km²;
- Antarctic- is the mainland Antarctica and the ocean floor under the surrounding oceans - 60.900.000 km²;
- Indo-Australian- The main tectonic platform, formed by the confluence of Indian and Australian plates - 58.900.000 km². Often divided into two blocks: Australian plate, originally part of the ancient continent of Gondwana - 47,000,000 km², Indian or Hindustan- was also part of the supercontinent Gondwana - 11.900.000 km²;
- South American- tectonic platform, which includes part of South America and part of the South Atlantic - 43.600.000 km².
How many lithospheric plates are there on earth?
There are 7 large lithospheric plates, if we take into account the Indo-Australian platform as a whole. This part of the earth's surface is usually divided into the Hindustan and Australian plates. Then there are 8 large blocks.
Summarize. The lithosphere is the earth's crust and the upper movable part of the mantle. The earthly basis is continental and oceanic. The earth's surface is divided into parts - lithospheric plates. They drift across the mantle like floating icebergs in the ocean. See Figure 5 -. The answer to the question about the number of lithospheric plates on Earth can be formulated as follows: In total, there are 8 large lithospheric platforms - with an area of more than 20 million km². and a large number of small platforms - less than 20 million km². The processes of interaction of plates with each other affect the structure of the Earth's surface, which is studied by science - tectonics of lithospheric plates.
Lithospheric plates - these are large blocks of the earth's crust and parts of the upper mantle, of which the lithosphere is composed.
What is the structure of the lithosphere.
At this time, on the border opposite from the fault, lithospheric plate collision... This collision can proceed in different ways depending on the types of colliding plates.
- If the oceanic and continental plates collide, the first sinks under the second. In this case, deep-sea trenches, island arcs (Japanese islands) or mountain ranges (Andes) arise.
- If two continental lithospheric plates collide, then at this point the edges of the plates are crumpled into folds, which leads to the formation of volcanoes and mountain ranges. Thus, the Himalayas arose on the border of the Eurasian and Indo-Australian plates. In general, if there are mountains in the center of the mainland, this means that it was once a place of collision of two lithospheric plates that had been fused into one.
Thus, the earth's crust is in constant motion. In its irreversible development, mobile areas are geosynclines- are transformed through long-term transformations into relatively calm areas - platform.
Lithospheric plates of Russia.
Russia is located on four lithospheric plates.
- Eurasian plate- most of the western and northern parts of the country,
- North American Plate- northeastern part of Russia,
- Amur lithospheric plate- the south of Siberia,
- Okhotsk plate- Sea of Okhotsk and its coast.
Fig 2. Map of lithospheric plates in Russia.
Relatively flat ancient platforms and mobile folded belts are distinguished in the structure of lithospheric plates. Plains are located on stable parts of the platforms, and mountain ranges are located in the area of folded belts.
Fig 3. Tectonic structure of Russia.
Russia is located on two ancient platforms (East European and Siberian). Within platforms stand out slabs and shields... A slab is an area of the earth's crust, the folded base of which is covered with a layer of sedimentary rocks. Shields, in contrast to slabs, have very little sediment and only a thin layer of soil.
In Russia, the Baltic shield on the East European platform and the Aldan and Anabar shields on the Siberian platform are distinguished.
Fig 4. Platforms, slabs and shields in Russia.
Together with part of the upper mantle, it consists of several very large blocks called lithospheric plates. Their thickness is different - from 60 to 100 km. Most of the plates include both continental and oceanic crust. There are 13 main plates, of which 7 are the largest: American, African, Indo-, Amur.
The plates lie on the plastic layer of the upper mantle (asthenosphere) and slowly move relative to each other at a speed of 1-6 cm per year. This fact was established by comparing images taken from artificial earth satellites. They suggest that the configuration in the future may be completely different from the modern one, since it is known that the American lithospheric plate is moving towards the Pacific, and the Eurasian is approaching the African, Indo-Australian, and also the Pacific. The American and African lithospheric plates are slowly diverging.
The forces that cause the divergence of the lithospheric plates arise when the material of the mantle moves. Powerful ascending currents of this substance push the plates apart, break the earth's crust, forming deep faults in it. Due to underwater lava eruptions, strata are formed along the faults. Freezing, they seem to heal wounds - cracks. However, the elongation is reinforced again and tears occur again. So, gradually increasing, lithospheric plates diverge in different directions.
There are fault zones on land, but most of them are in the oceanic ridges, where the earth's crust is thinner. The largest fault on land is located in the east. It stretches for 4000 km. The width of this fault is 80-120 km. Its outskirts are littered with extinct and active ones.
They collide along other plate boundaries. It happens in different ways. If the plates, one of which has an oceanic crust and the other continental, approach each other, then the lithospheric plate, covered by the sea, sinks under the continental one. When this occurs, arcs () or mountain ranges (). If two plates with a continental crust collide, then the edges of these plates are crushed into folds of rocks, and the formation of mountainous regions. This is how they arose, for example, on the border of the Eurasian and Indo-Australian plates. The presence of mountainous areas in internal parts The lithospheric plate suggests that once there was a border of two plates that were firmly soldered to each other and turned into a single, larger lithospheric plate.Thus, we can draw a general conclusion: the boundaries of the lithospheric plates are mobile areas to which volcanoes , zones, mountainous areas, mid-oceanic ridges, deep-sea depressions and trenches. It is at the boundary of lithospheric plates that form, the origin of which is associated with magmatism.
How did the continents and islands appear? What determines the name of the largest plates of the Earth? Where did our planet come from?
How it all began?
Everyone at least once thought about the origin of our planet. For deeply religious people, everything is simple: God created the Earth in 7 days - period. They are unshakable in their confidence, even knowing the names of the largest lithospheric plates formed as a result of the evolution of the planet's surface. For them, the birth of our stronghold is a miracle, and no arguments of geophysicists, natural scientists and astronomers are able to convince them.
Scientists, however, hold a different opinion based on hypotheses and assumptions. They just guess, put forward versions and come up with a name for everything. This also affected the largest plates of the Earth.
On the this moment it is not known for certain how our firmament appeared, but there are many interesting opinions. It was the scientists who unanimously decided that once there was a single gigantic continent, which was split into pieces as a result of cataclysms and natural processes. Also, scientists came up with not only the name of the largest plates of the Earth, but also designated the small ones.
Theory on the verge of fiction
For example, Immanuel Kant and Pierre Laplace, scientists from Germany, believed that the Universe emerged from a gas nebula, and the Earth is a gradually cooling planet, whose crust is nothing more than a cooled surface.
Another scientist, Otto Yulievich Schmidt, believed that the Sun, when passing through a gas-dust cloud, captured part of it with itself. His version is that our Earth was never completely molten matter and was originally a cold planet.
According to the theory of the English scientist Fred Hoyle, the Sun had its own twin star, which exploded like a supernova. Almost all of the debris was thrown over great distances, and the small amount remaining around the sun turned into planets. One of these fragments became the cradle of humanity.
Version as an axiom
The most common history of the origin of the Earth is as follows:
- About 7 billion years ago, a primary cold planet was formed, after which its interior began to gradually warm up.
- Then, during the so-called "lunar era", incandescent lava poured out to the surface in gigantic quantities. This entailed the formation of the primary atmosphere and served as an impetus for the formation of the earth's crust - the lithosphere.
- Thanks to the primary atmosphere, oceans appeared on the planet, as a result of which the Earth was covered with a dense shell, representing the outlines of oceanic trenches and continental protrusions. In those distant times, the area of water significantly prevailed over the area of land. By the way, the earth's crust and the upper part of the mantle are called the lithosphere, which forms the lithospheric plates that make up the general "appearance" of the Earth. The names of the largest plates correspond to their geographic location.
Giant rift
How did the continents and lithospheric plates form? About 250 million years ago, the Earth looked completely different from what it does now. Then there was only one on our planet, just a giant continent called Pangea. Its total area was impressive and was equal to the area of all currently existing continents, including islands. Pangea was washed on all sides by an ocean called Panthalassa. This huge ocean occupied the entire remaining surface of the planet.
However, the existence of the supercontinent turned out to be short-lived. Inside the Earth, processes raged, as a result of which the material of the mantle began to spread in different directions, gradually stretching the continent. Because of this, Pangea first split into 2 parts, forming two continents - Laurasia and Gondwana. Then these continents gradually split into many parts, which gradually parted in different directions. In addition to new continents, lithospheric plates have appeared. From the names of the largest plates, it becomes clear in which places giant faults were formed.
The remains of Gondwana are known to us Australia and Antarctica, as well as the South African and African lithospheric plates. It is proved that these plates are gradually diverging in our time - the speed of movement is 2 cm per year.
Fragments of Laurasia turned into two lithospheric plates - North American and Eurasian. Moreover, Eurasia consists not only of a fragment of Laurasia, but also of parts of Gondwana. The names of the largest plates that form Eurasia are Hindustan, Arabian, and Eurasian.
Africa is directly involved in the formation of the Eurasian continent. Its lithospheric plate is slowly approaching the Eurasian plate, forming mountains and hills. It was because of this "union" that the Carpathians, Pyrenees, Ore Mountains, Alps and Sudetes appeared.
List of lithospheric plates
The names of the largest slabs are as follows:
- South American;
- Australian;
- Eurasian;
- North American;
- Antarctic;
- Pacific;
- South American;
- Hindustan.
Medium slabs are:
- Arabian;
- Nazca;
- Scotia;
- Filipino;
- Coconut;
- Juan de Fuca.
Fb.ru
What are lithospheric plates. Lithospheric plates map
If you like interesting facts about nature, then surely you would like to know what lithospheric plates are.
So, lithospheric plates are huge blocks into which the solid surface layer of the earth is divided. Given the fact that the rocks beneath them are melted, the plates move slowly, at a rate of 1 to 10 centimeters per year.
Today, there are 13 largest lithospheric plates, which cover 90% of the earth's surface.
The largest lithospheric plates:
- Australian plate - 47,000,000 km²
- Antarctic plate - 60,900,000 km²
- Arabian subcontinent - 5,000,000 km²
- African Plate - 61,300,000 km²
- Eurasian plate - 67,800,000 km²
- Hindustan plate - 11,900,000 km²
- Coconut Plate - 2,900,000 km²
- Nazca Plate - 15,600,000 km²
- Pacific Plate - 103,300,000 km²
- North American Plate - 75.9 million km²
- Somali Plate - 16,700,000 km²
- South American Plate - 43.6 million km²
- Philippine Plate - 5,500,000 km²
Here it must be said that there is a continental and oceanic crust. Some plates are composed exclusively of one type of crust (for example, the Pacific plate), and some are of mixed types, when the plate begins in the ocean and smoothly transitions to the continent. The thickness of these layers is 70-100 kilometers.
Lithospheric plates float on the surface of a partially molten layer of the earth - the mantle. When the plates separate, the cracks between them are filled with a liquid rock called magma. When magma solidifies, it forms new crystalline rocks. We'll talk more about magma in the article on volcanoes.
Lithospheric plates map
The largest lithospheric plates (13 pcs.) At the beginning of the 20th century, the American F.B. Taylor and the German Alfred Wegener concurrently concluded that the location of the continents is slowly changing. By the way, this is, to a large extent, the cause of earthquakes. But scientists could not explain how this happens until the 60s of the twentieth century, until the theory of geological processes on the seabed was developed.
Map of the location of lithospheric plates It was the fossils that played the main role here. On different continents, fossilized remains of animals were found that clearly could not swim across the ocean. This gave rise to the assumption that once all continents were connected and animals calmly moved between them.
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Lithospheric plates
Lithospheric plates are the largest blocks of the lithosphere. The earth's crust, together with part of the upper mantle, consists of several very large blocks called lithospheric plates. Their thickness is different - from 60 to 100 km. Most of the plates include both continental and oceanic crust. There are 13 main plates, of which 7 are the largest: American, African, Antarctic, Indo-Australian, Eurasian, Pacific, Amur.
The plates lie on the plastic layer of the upper mantle (asthenosphere) and slowly move relative to each other at a speed of 1-6 cm per year. This fact was established by comparing images taken from artificial earth satellites. They suggest that the configuration of continents and oceans in the future may be completely different from the modern one, since it is known that the American lithospheric plate is moving towards the Pacific, and the Eurasian is approaching the African, Indo-Australian, and also the Pacific. The American and African lithospheric plates are slowly diverging.
The forces that cause the divergence of the lithospheric plates arise when the material of the mantle moves. Powerful ascending currents of this substance push the plates apart, break the earth's crust, forming deep faults in it. Due to the underwater eruptions of lava along the faults, strata of igneous rocks are formed. Freezing, they seem to heal wounds - cracks. However, the elongation is reinforced again and tears occur again. So, gradually increasing, the lithospheric plates diverge in different directions.
There are fault zones on land, but most of them are in the oceanic ridges at the bottom of the oceans, where the earth's crust is thinner. The largest fault on land is located in the east of Africa. It stretches for 4000 km. The width of this fault is 80-120 km. Its outskirts are dotted with extinct and active volcanoes.
They collide along other plate boundaries. It happens in different ways. If the plates, one of which has an oceanic crust and the other continental, approach each other, then the lithospheric plate, covered by the sea, sinks under the continental one. In this case, deep-sea trenches, island arcs (Japanese islands) or mountain ranges (Andes) arise. If two plates with a continental crust collide, then the edges of these plates are crushed into folds of rocks, volcanism and the formation of mountainous regions. This is how they arose, for example, on the border of the Eurasian and Indo-Australian plates of the Himalayas. The presence of mountainous areas in the inner parts of the lithospheric plate indicates that once there was a border of two plates that were firmly soldered to each other and turned into a single, larger lithospheric plate. Thus, a general conclusion can be drawn: the boundaries of the lithospheric plates are mobile areas to which volcanoes, earthquake zones, mountainous areas, mid-ocean ridges, deep-sea depressions and trenches are confined. It is at the boundary of the lithospheric plates that ore minerals are formed, the origin of which is associated with magmatism.
geographyofrussia.com
The theory of lithospheric plates on the world map: which is the largest
The theory of lithospheric plates is the most interesting direction in geography. As suggested by modern scientists, the entire lithosphere is divided into blocks that drift in the upper layer. Their speed is 2-3 cm per year. They are called lithospheric plates.
Founder of the theory of lithospheric plates
Who founded the theory of lithospheric plates? A. Wegener was one of the first in 1920 to make the assumption that the plates move horizontally, but he was not supported. And only in the 60s, the survey of the ocean floor confirmed his assumption.
The resurrection of these ideas led to the creation of the modern theory of tectonics. Its most important provisions were determined by a team of geophysicists from America D. Morgan, J. Oliver, L. Sykes and others in 1967-68.
Scientists cannot say in the affirmative what causes such displacements and how boundaries are formed. Back in 1910, Wegener believed that at the very beginning of the Paleozoic period, the Earth consisted of two continents.
Laurasia covered the area of present-day Europe, Asia (India was not included), North America. She was the northern mainland. Gondwana included South America, Africa, Australia.
About two hundred million years ago, these two continents merged into one - Pangea. And 180 million years ago, it is again divisible by two. Subsequently, Laurasia and Gondwana were also separated. This split created the oceans. Moreover, Wegener found evidence that confirmed his hypothesis about a single continent.
Map of lithospheric plates of the world
Over the billions of years during which the movement of the plates was carried out, they repeatedly merged and separated. The strength and vigor of the movement of continents is greatly influenced by the internal temperature of the Earth. With its increase, the speed of movement of the plates increases.
How many plates and how are lithospheric plates located on the world map today? Their boundaries are very conditional. Now there are 8 of the most important slabs. They cover 90% of the entire planet:
- Australian;
- Antarctic;
- African;
- Eurasian;
- Hindustan;
- Pacific;
- North American;
- South American.
Scientists constantly inspect and analyze the ocean floor, and investigate faults. They open new slabs and correct the lines of the old ones.
The largest lithospheric plate
What is the largest lithospheric plate? The most impressive is the Pacific plate, the crust of which is of the oceanic type. Its area is 10,300,000 km ². The size of this plate, like the size of the Pacific Ocean, is gradually decreasing.
In the south, it borders the Antarctic Plate. It creates the Aleutian Trench on the north and the Mariana Trench on the west.
Near California, where the eastern border passes, the plate moves along the length of the North American one. The San Andreas fault forms here.
What happens when the plates move
Lithospheric plates of the earth in their motion can diverge, merge, slide with neighboring ones. In the first variant, stretching areas with cracks are formed between them along the adjoining lines.
In the second option, compression zones are formed, which are accompanied by the overlap (obduction) of the plates on top of each other. In the third case, faults are observed, along the length of which they slide. In those places where the plates converge, they collide. This leads to the emergence of mountains.
As a result of collision, lithospheric plates form:
- Tectonic faults called rift valleys. They form in stretch zones;
- In the case when a collision of plates with a continental type of crust occurs, then they talk about convergent boundaries. This causes the formation of large mountain systems. The Alpine-Himalayan system was the result of the collision of three plates: Eurasian, Indo-Australian, African;
- If plates with different types of crust collide (one is continental, the other is oceanic), mountains are formed on the coast, and deep depressions (trenches) in the ocean. An example of such a formation is the Andes and the Peruvian Basin. It happens that island arcs are formed together with the troughs (Japanese islands). This is how the Mariana Islands and the Trench were formed.
The lithospheric plate of Africa includes the African continent and has an oceanic type. It is there that the largest fault is located. Its length is 4000 km, and its width is 80-120. Its extremities are covered with numerous active and extinct volcanoes.
Lithospheric plates of the world, which have an oceanic type of crustal structure, are often called oceanic. These include: Pacific, Coconut, Nazca. They occupy more than half of the space of the World Ocean.
There are three of them in the Indian Ocean (Indo-Australian, African, Antarctic). The names of the plates correspond to the names of the continents that it washes. Lithospheric plates of the ocean are separated by underwater ridges.
Tectonics as a science
Plate tectonics studies their movement, as well as changes in the structure and composition of the Earth in a given area in a certain period of time. It assumes that not the continents are drifting, but the lithospheric plates.
It is this movement that causes earthquakes and volcanic eruptions. It has been confirmed by satellites, but the nature of such movement and its mechanisms are still unknown.
vsesravnenie.ru
The movement of lithospheric plates. Large lithospheric plates. Names of lithospheric plates
Lithospheric plates of the Earth are huge blocks. Their foundation is formed by granite metamorphosed igneous rocks strongly crumpled into folds. The names of the lithospheric plates will be given in the article below. From above they are covered with a three-four-kilometer "cover". It is formed from sedimentary rocks. The platform has a relief consisting of individual mountain ranges and vast plains. Further, the theory of the movement of lithospheric plates will be considered.
The emergence of a hypothesis
The theory of the movement of lithospheric plates appeared at the beginning of the twentieth century. Subsequently, she was destined to play a major role in planetary exploration. Scientist Taylor, and after him Wegener, put forward a hypothesis that over time there is a drift of lithospheric plates in the horizontal direction. However, in the thirties of the 20th century, a different opinion was established. According to him, the movement of lithospheric plates was carried out vertically. This phenomenon was based on the process of differentiation of the planet's mantle matter. It came to be called fixism. This name was due to the fact that the permanently fixed position of the crustal areas relative to the mantle was recognized. But in 1960, after the discovery of the global system of mid-ocean ridges that encircle the entire planet and come out on land in some areas, there was a return to the hypothesis of the beginning of the 20th century. However, the theory took on a new form. Block tectonics has become a leading hypothesis in the sciences that study the structure of the planet.
Basic Provisions
It was determined that large lithospheric plates exist. Their number is limited. There are also smaller lithospheric plates of the Earth. The boundaries between them are drawn along the thickening in the foci of earthquakes.
The names of the lithospheric plates correspond to the continental and oceanic regions located above them. There are only seven boulders with a huge area. The largest lithospheric plates are South and North American, Euro-Asian, African, Antarctic, Pacific and Indo-Australian.
Lumps floating in the asthenosphere are solid and rigid. The above areas are the main lithospheric plates. In accordance with the initial ideas, it was believed that the continents make their way through the ocean floor. In this case, the movement of lithospheric plates was carried out under the influence of an invisible force. As a result of the studies carried out, it was revealed that the blocks float passively over the mantle material. It is worth noting that their direction is at first vertical. The mantle material rises upward under the ridge crest. Then there is a spread in both directions. Accordingly, there is a divergence of the lithospheric plates. This model presents the ocean floor as a giant conveyor belt. It comes to the surface in the rift regions of the mid-oceanic ridges. Then it hides in deep-sea trenches.
The divergence of lithospheric plates provokes the expansion of oceanic beds. However, the volume of the planet, despite this, remains constant. The fact is that the birth of a new crust is compensated by its absorption in the areas of subduction (underthrust) in deep-sea trenches. 
Why does the movement of lithospheric plates occur?
The reason lies in the thermal convection of the planet's mantle material. The lithosphere undergoes stretching and uplift, which occurs above the ascending branches from convective currents. This provokes the movement of the lithospheric plates to the sides. With increasing distance from the mid-oceanic rifts, the platform compaction occurs. It becomes heavier, its surface sinks down. This explains the increase in ocean depth. As a result, the platform sinks into deep-sea trenches. With the attenuation of the ascending flows from the heated mantle, it cools and sinks with the formation of basins that are filled with sediments.
Lithospheric plate collision zones are areas where crust and plate are compressed. In this regard, the power of the former is increased. As a result, the upward movement of lithospheric plates begins. It leads to the formation of mountains.
Research
The study today is carried out using geodetic methods. They allow us to draw a conclusion about the continuity and ubiquity of processes. The zones of collision of lithospheric plates are also revealed. The lifting speed can be up to ten millimeters.
Horizontally large lithospheric plates float somewhat faster. In this case, the speed can be up to ten centimeters during the year. So, for example, St. Petersburg has already risen by a meter over the entire period of its existence. The Scandinavian Peninsula - 250 m in 25,000 years. The mantle material moves relatively slowly. However, as a result, earthquakes, volcanic eruptions and other phenomena occur. This allows us to conclude about the high power of material movement.
Using the tectonic position of the plates, the researchers explain a variety of geological phenomena. At the same time, during the study, it became clear that the complexity of the processes taking place with the platform is much greater than it seemed at the very beginning of the hypothesis.
Plate tectonics could not explain changes in the intensity of deformation and movement, the presence of a global stable network of deep faults, and some other phenomena. The question also remains open about historical beginning actions. Direct signs indicating plate tectonic processes have been known since the Late Proterozoic. However, a number of researchers recognize their manifestation from the Archean or Early Proterozoic.
Expanding Research Opportunities
The advent of seismic tomography led to the transition of this science to a qualitative new level... In the mid-eighties of the last century, deep geodynamics became the most promising and young direction of all the existing earth sciences. However, the solution of new problems was carried out using not only seismotomography. Other sciences also came to the rescue. These include, in particular, experimental mineralogy.
Thanks to the availability of new equipment, it became possible to study the behavior of substances at temperatures and pressures corresponding to the maximum at the depths of the mantle. Also, the research used the methods of isotope geochemistry. This science studies, in particular, the isotopic balance of rare elements, as well as noble gases in various earthly shells. In this case, the indicators are compared with meteorite data. Methods of geomagnetism are used, with the help of which scientists are trying to reveal the causes and mechanism of reversals in the magnetic field.
Modern painting
The platform tectonics hypothesis continues to provide a satisfactory explanation for the development of the crust of oceans and continents over at least the last three billion years. At the same time, there are satellite measurements, according to which the fact is confirmed that the main lithospheric plates of the Earth do not stand still. As a result, a certain picture emerges.
In the cross section of the planet, there are three most active layers. The capacity of each of them is several hundred kilometers. It is assumed that the main role in global geodynamics is assigned to them. In 1972, Morgan substantiated the hypothesis of ascending mantle jets put forward in 1963 by Wilson. This theory explained the phenomenon of intraplate magnetism. The resulting plume tectonics has become increasingly popular over time. 
Geodynamics
With its help, the interaction of rather complex processes that occur in the mantle and crust is considered. In accordance with the concept outlined by Artyushkov in his work "Geodynamics", gravitational differentiation of matter acts as the main source of energy. This process is noted in the lower mantle.
After the heavy components (iron, etc.) are separated from the rock, a lighter mass of solids remains. She descends into the core. The location of the lighter layer under the heavy is unstable. In this regard, the accumulating material collects periodically into rather large blocks that float to the upper layers. The size of such formations is about one hundred kilometers. This material was the basis for the formation of the Earth's upper mantle.
The lower layer is probably an undifferentiated primary substance. In the course of the evolution of the planet, due to the lower mantle, the upper mantle grows and the core increases. It is more likely that blocks of light material rise in the lower mantle along the channels. The temperature of the mass in them is quite high. At the same time, the viscosity is significantly reduced. An increase in temperature is facilitated by the release of a large amount of potential energy in the process of ascent of matter into the region of gravity over a distance of about 2000 km. In the course of movement along such a channel, a strong heating of light masses occurs. In this regard, matter enters the mantle, having a sufficiently high temperature and significantly less weight in comparison with the surrounding elements.
Due to the lowered density, light material floats into the upper layers to a depth of 100-200 kilometers or less. With decreasing pressure, the melting point of the components of the substance decreases. After primary differentiation at the core-mantle level, a secondary one occurs. At shallow depths, light matter undergoes partial melting. During differentiation, denser substances are released. They sink into the lower layers of the upper mantle. The lighter components that stand out, respectively, rise up.
The complex of movements of substances in the mantle associated with the redistribution of masses with different densities as a result of differentiation is called chemical convection. The rise of light masses occurs at intervals of about 200 million years. At the same time, intrusion into the upper mantle is not observed everywhere. In the lower layer, the channels are located at a fairly large distance from each other (up to several thousand kilometers). 
Lifting lumps
As mentioned above, in those zones where large masses of light heated material are introduced into the asthenosphere, it partially melts and differentiates. In the latter case, the selection of components and their subsequent emergence are noted. They quickly pass through the asthenosphere. Upon reaching the lithosphere, their speed decreases. In some areas, matter forms clusters of anomalous mantle. They usually occur in the upper layers of the planet.
Abnormal mantle
Its composition roughly corresponds to normal mantle material. The difference between the anomalous cluster is more heat(up to 1300-1500 degrees) and reduced speed of elastic longitudinal waves.
The influx of matter under the lithosphere provokes isostatic uplift. Due to the increased temperature, the anomalous cluster has a lower density than the normal mantle. In addition, there is a low viscosity of the composition.
In the process of entering the lithosphere, the anomalous mantle is rather quickly distributed along the base. At the same time, it displaces the denser and less heated matter of the asthenosphere. In the course of movement, the anomalous accumulation fills those areas where the base of the platform is in a raised state (traps), and it flows around deeply submerged areas. As a result, in the first case, isostatic uplift is noted. Over submerged areas, the crust remains stable.
Traps
The process of cooling the mantle upper layer and crust to a depth of about one hundred kilometers is slow. In general, it takes several hundred million years. In this regard, heterogeneities in the thickness of the lithosphere, explained by horizontal temperature differences, have a fairly large inertia. In the event that the trap is located near the upward flow of the anomalous cluster from the depths, a large amount of matter is captured by the highly heated one. As a result, a rather large rock element is formed. In accordance with this scheme, high uplifts occur at the site of epiplatform orogenesis in folded belts.
Description of processes
In the trap, the anomalous layer is compressed by 1–2 kilometers during cooling. The bark on the top sinks. In the formed trough, sediments begin to accumulate. Their severity contributes to an even greater sinking of the lithosphere. As a result, the depth of the basin can be from 5 to 8 km. At the same time, during compaction of the mantle in the lower part of the basalt layer in the crust, a phase transformation of the rock into eclogite and garnet granulite can be noted. Due to the heat flow escaping from the anomalous substance, the overlying mantle heats up and its viscosity decreases. In this regard, a gradual displacement of the normal accumulation is observed.
Horizontal offsets
With the formation of uplifts in the process of anomalous mantle inflow to the crust on the continents and oceans, the potential energy stored in the upper layers of the planet increases. To dump excess substances, they tend to disperse to the sides. As a result, additional stresses are formed. Various types of movement of plates and crust are associated with them.
The expansion of the ocean floor and the floating of the continents are a consequence of the simultaneous expansion of the ridges and the immersion of the platform into the mantle. Under the first are large masses of highly heated anomalous matter. In the axial part of these ridges, the latter is located directly under the crust. The lithosphere is much less powerful here. At the same time, the abnormal mantle spreads in the area of increased pressure - in both directions from under the ridge. At the same time, it tears apart the ocean crust quite easily. The crevice is filled with basalt magma. She, in turn, is smelted from the anomalous mantle. As the magma solidifies, a new oceanic crust is formed. This is how the bottom grows. 
Process features
Below the middle ridges, the anomalous mantle has a reduced viscosity due to the increased temperature. The substance is capable of spreading quickly enough. In this regard, the growth of the bottom occurs at an increased rate. The oceanic asthenosphere also has a relatively low viscosity.
The main lithospheric plates of the Earth float from ridges to dive sites. If these sites are in the same ocean, then the process occurs at a relatively high speed. This situation is typical today for the Pacific Ocean. If the growth of the bottom and subsidence occurs in different areas, then the continent located between them drifts in the direction where the deepening occurs. Under the continents, the viscosity of the asthenosphere is higher than under the oceans. Due to the friction that occurs, significant resistance to movement appears. As a result, the rate at which the bottom expands decreases if there is no compensation for the immersion of the mantle in the same area. Thus, the sprawl in Pacific is faster than the Atlantic.
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Wonderful-planet - Lithospheric plates.
You are in the details in the section: LithosphereLithospheric plates are large blocks of the earth's crust and parts of the upper mantle that make up the lithosphere.
What is the structure of the lithosphere. - The main lithospheric plates. - Map of the Earth's lithosphere. - The movement of the lithosphere. - Lithospheric plates of Russia.
What is the structure of the lithosphere.
The lithosphere is composed of large blocks called lithospheric plates. Lithospheric blocks are 1-10,000 km across, and their thickness varies from 60 to 100 km. Most of the lithospheric blocks include both the continental crust and oceanic ones. Although there are cases when the lithospheric plate consists exclusively of the oceanic crust (Pacific plate).
Lithospheric plates consist of highly folded igneous, metamorphosed and granite rocks lying at the base, and a 3-4 km layer of sedimentary rocks on top.
At the base of each continent lies one or more ancient platforms, along the border of which there is a chain of mountain ranges. Within the platform, the relief is usually represented by flat plains with separate mountain ranges.
The boundaries of the lithospheric plates are distinguished by high tectonic, seismic and volcanic activity. Slab boundaries are three types: divergent, convergent and transform. The outlines of lithospheric plates are constantly changing. Large ones split, small ones are soldered together. Some plates can sink into the Earth's mantle.
As a rule, only three lithospheric plates converge at one point on the globe. A configuration where four or more plates converge at one point is unstable, and quickly collapses over time.
The main lithospheric plates of the Earth.
Most of the earth's surface, about 90%, is covered by 14 major lithospheric plates. This is:
- Australian plate
- Antarctic plate
- Arabian subcontinent
- African plate
- Eurasian plate
- Hindustan plate
- Coconut plate
- Nazca slab
- Pacific plate
- Scotia slab
- North American Plate
- Somali plate
- South American Plate
- Philippine plate
Fig 1. Map of the Earth's lithospheric plates.
The movement of the Earth's lithosphere.
Lithospheric plates are constantly moving relative to each other at a speed of up to several tens of centimeters per year. This fact was recorded by photographs taken from artificial earth satellites. At present, it is known that the American lithospheric plate is moving towards the Pacific, and the Eurasian is approaching the African, Indo-Australian, and also the Pacific. The American and African lithospheric plates are slowly diverging.
Lithospheric plates - the main components of the lithosphere - lie on the plastic layer of the upper mantle - the asthenosphere. It is she who plays the main role in the movement of the earth's crust. The substance of the asthenosphere as a result of thermal convection (heat transfer in the form of jets and streams) slowly "flows", dragging along the blocks of the lithosphere and causing them to move horizontally. If the substance of the asthenosphere rises or falls, this leads to a vertical movement of the earth's crust. The rate of vertical movement of the lithosphere is much less than the horizontal one - only up to 1-2 tens of millimeters per year.
With the vertical movement of the lithosphere above the ascending branches of the convective currents of the asthenosphere, ruptures of lithospheric plates occur and faults are formed. Lava rushes into the faults and, cooling down, fills empty cavities with strata of igneous rocks. But then the increasing stretching of the moving lithospheric plates again leads to a fault. So, gradually growing in places of faults, lithospheric plates diverge in different directions. This strip of horizontal plate divergence is called the rift zone. With distance from the rift zone, the lithosphere cools, becomes heavier, thickens and, as a result, sinks deeper into the mantle, forming areas of lower relief.
Fault zones are observed both on land and in the ocean. The largest continental fault, more than 4000 km long and 80-120 km wide, is located in Africa. A large number of active and dormant volcanoes are located on the slopes of the fault.
At this time, a collision of lithospheric plates occurs on the boundary opposite to the fault. This collision can proceed in different ways depending on the types of colliding plates.
- If the oceanic and continental plates collide, the first sinks under the second. In this case, deep-sea trenches, island arcs (Japanese islands) or mountain ranges (Andes) arise.
- If two continental lithospheric plates collide, then at this point the edges of the plates are crumpled into folds, which leads to the formation of volcanoes and mountain ranges. Thus, the Himalayas arose on the border of the Eurasian and Indo-Australian plates. In general, if there are mountains in the center of the mainland, this means that it was once a place of collision of two lithospheric plates that had been fused into one.
Thus, the earth's crust is in constant motion. In its irreversible development, mobile areas - geosynclines - are transformed through long-term transformations into relatively calm areas - platforms.
Lithospheric plates of Russia.
Russia is located on four lithospheric plates.
- Eurasian plate - most of the western and northern parts of the country,
- North American Plate - northeastern part of Russia,
- Amur lithospheric plate - southern Siberia,
- Okhotsk plate - Sea of Okhotsk and its coast.
Fig 2. Map of lithospheric plates in Russia.
Relatively flat ancient platforms and mobile folded belts are distinguished in the structure of lithospheric plates. Plains are located on stable parts of the platforms, and mountain ranges are located in the area of folded belts.
Fig 3. Tectonic structure of Russia.
Russia is located on two ancient platforms (East European and Siberian). Within the platforms, slabs and shields are distinguished. A slab is an area of the earth's crust, the folded base of which is covered with a layer of sedimentary rocks. Shields, in contrast to slabs, have very little sediment and only a thin layer of soil.
In Russia, the Baltic shield on the East European platform and the Aldan and Anabar shields on the Siberian platform are distinguished.
Fig 4. Platforms, slabs and shields in Russia.
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The lithospheric plate is ... What is the lithospheric plate?
The lithospheric plate is a large stable area of the earth's crust, part of the lithosphere. According to the theory of plate tectonics, lithospheric plates are limited by zones of seismic, volcanic and tectonic activity - the boundaries of the plate. There are three types of plate boundaries: divergent, convergent, and transform.
From geometric considerations, it is clear that only three plates can converge at one point. A configuration in which four or more slabs converge at one point is unstable and quickly deteriorates over time.
There are basically two different kinds Earth's crust - continental crust and oceanic crust. Some lithospheric plates are composed exclusively of oceanic crust (for example, the largest Pacific plate), others consist of a block of continental crust, soldered into the oceanic crust.
Lithospheric plates are constantly changing their shape, they can split as a result of rifting and solder, forming a single plate as a result of collision. Lithospheric plates can also sink into the planet's mantle, reaching the depths of the core. On the other hand, the division of the earth's crust into plates is ambiguous, and as geological knowledge accumulates, new plates are identified, and some plate boundaries are recognized as non-existent. Therefore, the outlines of the plates change over time in this sense. This is especially true of small plates, for which geologists have proposed many kinematic reconstructions, often mutually exclusive.
Map of lithospheric plates Tectonics plates (preserved surfaces)
More than 90% of the Earth's surface is covered with 14 largest lithospheric plates:
Medium slabs:
Microplates
Disappeared slabs:
Disappeared oceans:
Supercontinents:
Notes (edit)
Calculation of the thickness of the slab foundation
Lithospheric plates- large rigid blocks of the Earth's lithosphere, limited by seismically and tectonically active fault zones.
The plates, as a rule, are separated by deep faults and move along the viscous layer of the mantle relative to each other at a speed of 2-3 cm per year. At the points of convergence of the continental plates, their collision occurs, mountain belts ... When the continental and oceanic plates interact, the plate with the oceanic crust is pushed under the plate with the continental crust, resulting in the formation of deep-sea trenches and island arcs.
The movement of lithospheric plates is associated with the movement of matter in the mantle. IN separate parts mantle, there are powerful streams of heat and matter rising from its depths to the surface of the planet.
More than 90% of the Earth's surface is covered 13 th largest lithospheric plates.
The rift– a huge rift in the earth's crust, formed when it is stretched horizontally (that is, where the flows of heat and matter diverge). Magma erupts in the rifts, new faults, horsts, and grabens appear. Mid-ocean ridges are being formed.
The first continental drift hypothesis (i.e. horizontal movement of the earth's crust) put forward at the beginning of the twentieth century A. Wegener... Based on it, theory of lithospheric or m. According to this theory, the lithosphere is not a monolith, but consists of large and small plates "floating" on the asthenosphere. The border areas between lithospheric plates are called seismic belts - these are the most "restless" areas of the planet.
The earth's crust is divided into stable (platforms) and mobile areas (folded areas - geosynclines).
- powerful underwater mountain structures within the ocean floor, most often occupying the middle position. Near the mid-oceanic ridges, the lithospheric plates move apart and a young basaltic oceanic crust appears. The process is accompanied by intense volcanism and high seismicity.
Continental rift zones are, for example, the East African rift system, the Baikal rift system. Rifts, like mid-ocean ridges, are characterized by seismic activity and volcanism.
Plate tectonics- a hypothesis suggesting that the lithosphere is broken up into large plates that move horizontally along the mantle. Near the mid-oceanic ridges, lithospheric plates move apart and grow due to matter rising from the bowels of the Earth; in deep-sea trenches, one plate moves under the other and is absorbed by the mantle. In places of collision of plates, folded structures are formed.
