Internal structure of the earth. Map of the structure of the earth's crust
The Earth's crust, or geosphere, is the outer solid shell of the Earth. Beneath the crust is the mantle, which differs from it in composition and physical properties. The structure of the mantle is more dense, as it contains mainly refractory components. The mantle is separated from the crust by the Mohorovicic boundary, or Moho, at which the speed of seismic waves increases sharply. Most of the outer crust is covered with hydrosphere, the smaller part borders with atmospheric air. In accordance with this, the earth's crust is distinguished between oceanic and continental types, which have different structures. total weight earth's crust, according to scientists, makes up only 0.5% of the total mass of the planet.
Structure and composition
The oceanic crust is dominated by a basalt layer. According to the theory of plate tectonics, this type of crust forms continuously at mid-ocean ridges, then moves away from them and is absorbed into the mantle in subduction regions. Therefore, the oceanic crust is considered relatively young. In different geographical areas The thickness of the oceanic crust varies from 5 to 7 km. It consists of basalt and sedimentary layers. Its thickness practically does not change over time because it depends on the amount of melt released from the mantle in the areas of mid-ocean ridges. Also, the thickness of the oceanic crust is partially determined by the thickness of the sedimentary layer at the bottom of the oceans and seas. The thickness of the earth's crust increases with distance from areas of mid-ocean ridges. The continental (continental) crust is characterized by a three-layer structure. The top layer is a cover of sedimentary rocks, interrupted in places. This cover is well developed, but rarely reaches great thickness. Middle granite layer continental crust makes up most of the entire cortex. It consists of gneisses and granite, has low density and ancient history education. A large proportion of the mass of these rocks was formed about 3 billion years ago. The lower basalt layer consists of metamorphic rocks - granulites and similar substances. The average thickness of the continental crust is about 35 km, the maximum under the mountain ranges is 70-75 km. The bark of this species contains many chemical elements and their connections. About half of the mass is oxygen, a quarter is silicon, the rest is Al, Fe, Ca, Na, K, Mg, H, Ti, C, Cl, P, S, N, Mn, F, Ba.
In the transition zone from continents to oceans, a crust of transitional (intermediate) type (suboceanic or subcontinental) was formed. The transitional crust is characterized by a complex combination of features of the earth's crust of the two types described above. Intermediate crust corresponds to areas such as shelves, island arcs, and ocean ridges.
In the vast majority of areas, the earth's crust is in a state of relative isostatic equilibrium. Violation of isostatic compensation is observed on volcanic islands, oceanic basins, and island arcs. Here the earth's crust is constantly subject to tectonic movements. Large faults in the earth's crust can be considered as a result of displacement tectonic plates in the areas of their junctions. In the structure of the crust, a distinction is made between relatively quiet areas (platforms) and mobile ones (folded belts).
Related materials:
The globe has several shells: - an air shell, - a water shell, - a solid shell.
The third beyond the distance from the Sun planet Earth has a radius of 6370 km, an average density of 5.5 g/cm2. In the internal structure of the Earth, it is customary to distinguish the following layers:
Earth's crust — upper layer Earth in which living organisms can exist. The thickness of the earth's crust can be from 5 to 75 km.
mantle- a solid layer that is located below the earth's crust. Its temperature is quite high, but the substance is in a solid state. The thickness of the mantle is about 3,000 km.
core- the central part of the globe. Its radius is approximately 3,500 km. The temperature inside the core is very high. The core is believed to consist mainly of molten metal,
presumably iron.
Earth's crust
There are two main types of the earth's crust - continental and oceanic, plus an intermediate, subcontinental.
The earth's crust is thinner under the oceans (about 5 km) and thicker under the continents (up to 75 km). It is heterogeneous; three layers are distinguished: basalt (lying at the bottom), granite and sedimentary (upper). The continental crust consists of three layers, while the oceanic crust has no granite layer. The earth's crust formed gradually: first a basalt layer was formed, then a granite layer; the sedimentary layer continues to form to this day.
- the substance that makes up the earth's crust. Rocks are divided into the following groups:
1. Igneous rocks. They are formed when magma solidifies deep within the earth's crust or on the surface.
2. Sedimentary rocks. They are formed on the surface, formed from the products of destruction or change of other rocks and biological organisms.
3. Metamorphic rocks. They are formed in the thickness of the earth's crust from other rocks under the influence of certain factors: temperature, pressure.
The Earth's crust is of great importance for our life, for research of our planet.
This concept is closely related to others that characterize processes occurring inside and on the surface of the Earth.
What is the earth's crust and where is it located?
The Earth has a holistic and continuous shell, which includes: the earth's crust, the troposphere and stratosphere, which are the lower part of the atmosphere, the hydrosphere, the biosphere and the anthroposphere.
They interact closely, penetrating each other and constantly exchanging energy and matter. The earth's crust is usually called the outer part of the lithosphere - the solid shell of the planet. Most its outer side is covered by the hydrosphere. The remaining, smaller part is affected by the atmosphere.
Beneath the Earth's crust is a denser and more refractory mantle. They are separated by a conventional border named after the Croatian scientist Mohorovic. Its peculiarity is a sharp increase in the speed of seismic vibrations.
To get an idea of the earth's crust, various scientific methods. However, obtaining specific information is only possible by drilling to great depths.
One of the objectives of such research was to establish the nature of the boundary between the upper and lower continental crust. The possibilities of penetrating the upper mantle using self-heating capsules made of refractory metals were discussed.
Structure of the earth's crust
Beneath the continents are its sedimentary, granite and basalt layers, the total thickness of which is up to 80 km. Rocks, called sedimentary rocks, are formed by the deposition of substances on land and in water. They are located mainly in layers.
- clay
- shale
- sandstones
- carbonate rocks
- rocks of volcanic origin
- coal and other rocks.
The sedimentary layer helps to learn more deeply about natural conditions on earth that were on the planet in time immemorial. This layer can have different thicknesses. In some places it may not exist at all, in other, mainly large depressions, it can be 20-25 km.
Temperature of the earth's crust
An important energy source for the inhabitants of the Earth is the heat of its crust. The temperature increases as you go deeper into it. The 30-meter layer closest to the surface, called the heliometric layer, is associated with the heat of the sun and fluctuates depending on the season.
In the next, thinner layer, which increases in a continental climate, the temperature is constant and corresponds to the indicators of a specific measurement location. In the geothermal layer of the crust, the temperature is related to internal heat planet and grows as you go deeper into it. It is different in different places and depends on the composition of the elements, depth and conditions of their location.
It is believed that the temperature increases on average by three degrees as you go deeper for every 100 meters. Unlike the continental part, temperatures under the oceans are rising faster. After the lithosphere there is a plastic high-temperature shell, the temperature of which is 1200 degrees. It is called the asthenosphere. There are places with molten magma in it.
Penetrating into the earth's crust, the asthenosphere can pour out molten magma, causing volcanic phenomena.
Characteristics of the Earth's crust
The Earth's crust has a mass of less than half a percent of the total mass of the planet. It is the outer shell of the stone layer in which the movement of matter occurs. This layer, which has a density half that of the Earth. Its thickness varies between 50-200 km.
The uniqueness of the earth's crust is that it can be of continental and oceanic types. The continental crust has three layers, the top of which is formed by sedimentary rocks. The oceanic crust is relatively young and its thickness varies slightly. It is formed due to mantle substances from oceanic ridges.
earth's crust characteristics photo
The thickness of the crust layer under the oceans is 5-10 km. Its peculiarity is constant horizontal and oscillatory movements. Most of the crust is basalt.
The outer part of the earth's crust is the solid shell of the planet. Its structure is distinguished by the presence of movable areas and relatively stable platforms. Lithospheric plates move relative to each other. The movement of these plates can cause earthquakes and other disasters. The patterns of such movements are studied by tectonic science.
Functions of the earth's crust
The main functions of the earth's crust are:
- resource;
- geophysical;
- geochemical.
The first of them indicates the presence of the Earth's resource potential. It is primarily a collection of mineral reserves located in the lithosphere. In addition, the resource function includes a number of environmental factors that ensure the life of humans and other biological objects. One of them is the tendency for a hard surface deficit to form.
You can't do that. let's save our Earth photo
Thermal, noise and radiation effects implement the geophysical function. For example, the problem of natural background radiation arises, which is generally safe on the earth’s surface. However, in countries such as Brazil and India it can be hundreds of times higher than permissible. It is believed that its source is radon and its decay products, as well as certain types of human activity.
The geochemical function is associated with problems of chemical pollution harmful to humans and other representatives of the animal world. Various substances with toxic, carcinogenic and mutagenic properties enter the lithosphere.
They are safe when they are in the bowels of the planet. Zinc, lead, mercury, cadmium and others extracted from them heavy metals may pose a great danger. In processed solid, liquid and gaseous form, they enter the environment.
What is the Earth's crust made of?
Compared to the mantle and core, the Earth's crust is a fragile, hard and thin layer. It consists of a relatively light substance, which includes about 90 natural elements. They are found in different places in the lithosphere and with varying degrees of concentration.
The main ones are: oxygen, silicon, aluminum, iron, potassium, calcium, sodium magnesium. 98 percent of the earth's crust consists of them. About half of this is oxygen, and over a quarter is silicon. Thanks to their combinations, minerals such as diamond, gypsum, quartz, etc. are formed. Several minerals can form a rock.
- An ultra-deep well on the Kola Peninsula made it possible to get acquainted with mineral samples from a 12-kilometer depth, where rocks close to granites and shales were discovered.
- The greatest thickness of the crust (about 70 km) was revealed under mountain systems. Under flat areas it is 30-40 km, and under the oceans it is only 5-10 km.
- Much of the crust forms an ancient, low-density upper layer consisting primarily of granites and shales.
- The structure of the earth's crust resembles the crust of many planets, including the Moon and their satellites.
Earth's crust – the outer solid shell of the Earth, the upper part of the lithosphere. The earth's crust is separated from the Earth's mantle by the Mohorovicic surface.
It is customary to distinguish continental and oceanic crust, which differ in their composition, power, structure and age. Continental crust located under continents and their underwater margins (shelves). The earth's crust of continental type, with a thickness of 35-45 km, is located under the plains up to 70 km in the area of young mountains. The most ancient sections of the continental crust have a geological age exceeding 3 billion years. It consists of the following shells: weathering crust, sedimentary, metamorphic, granite, basalt.
Oceanic crust much younger, its age does not exceed 150-170 million years. It has less power – 5-10 km. There is no boundary layer within the oceanic crust. In the structure of the oceanic crust, the following layers are distinguished: unconsolidated sedimentary rocks (up to 1 km), volcanic oceanic, which consists of compacted sediments (1-2 km), basalt (4-8 km).
The rocky shell of the Earth does not represent a single whole. It consists of separate blocks – lithospheric plates. Total for globe there are 7 large and several smaller plates. The large ones include the Eurasian, North American, South American, African, Indo-Australian (Indian), Antarctic and Pacific plates. Within all major plates, with the exception of the last, continents are located. The boundaries of lithospheric plates usually run along mid-ocean ridges and deep-sea trenches.
Lithospheric plates constantly changing: two plates can be soldered into a single one as a result of a collision; As a result of rifting, the slab may split into several parts. Lithospheric plates can sink into the earth's mantle, reaching the earth's core. Therefore, the division of the earth's crust into plates is not unambiguous: with the accumulation of new knowledge, some plate boundaries are recognized as non-existent, and new plates are identified.
Within lithospheric plates there are areas with various types earth's crust. Thus, the eastern part of the Indo-Australian (Indian) plate is a continent, and the western part is located at the base of the Indian Ocean. The African Plate has continental crust surrounded on three sides by oceanic crust. The mobility of the atmospheric plate is determined by the relationship between the continental and oceanic crust within its boundaries.
When lithospheric plates collide, a folding of rock layers. Pleated belts – mobile, highly dissected areas of the earth's surface. There are two stages in their development. On initial stage The earth's crust experiences predominantly subsidence, sedimentary rocks accumulate and metamorphose. On final stage subsidence is replaced by uplift, rocks are crushed into folds. Over the past billion years, there have been several eras of intense mountain building on Earth: the Baikal, Caledonian, Hercynian, Mesozoic and Cenozoic orogenies. In accordance with this, various folding areas are distinguished.
Subsequently, the rocks that make up the folded region lose their mobility and begin to collapse. Sedimentary rocks accumulate on the surface. Stable areas of the earth's crust are formed –
platforms. They usually consist of a folded foundation (remains of ancient mountains), covered on top by layers of horizontally occurring sedimentary rocks that form a cover. According to the age of the foundation, ancient and young platforms are distinguished. Areas of rock where the foundation is buried deep and covered by sedimentary rocks are called slabs. The places where the foundation reaches the surface are called shields. They are more typical for ancient platforms. At the base of all continents there are ancient platforms, the edges of which are folded areas of different ages. 
The spread of platform and fold regions can be seen on tectonic geographical map, or on a map of the structure of the earth's crust.
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The earth's crust in the scientific sense is the uppermost and hardest geological part of the shell of our planet.
Scientific research allows us to study it thoroughly. This is facilitated by repeated drilling of wells both on continents and on the ocean floor. The structure of the earth and the earth's crust in different parts of the planet differs both in composition and characteristics. The upper boundary of the earth's crust is the visible relief, and the lower boundary is the zone of separation of the two environments, which is also known as the Mohorovicic surface. It is often referred to simply as the “M boundary.” It received this name thanks to the Croatian seismologist Mohorovicic A. For many years he observed the speed of seismic movements depending on the depth level. In 1909, he established the existence of a difference between the earth's crust and the hot mantle of the earth. The M boundary lies at the level where the speed of seismic waves increases from 7.4 to 8.0 km/s.
Chemical composition of the Earth
Studying the shells of our planet, scientists have made interesting and even stunning conclusions. The structural features of the earth's crust make it similar to the same areas on Mars and Venus. More than 90% of its constituent elements are represented by oxygen, silicon, iron, aluminum, calcium, potassium, magnesium, and sodium. Combining with each other in various combinations, they form homogeneous physical bodies - minerals. They can be included in rocks in different concentrations. The structure of the earth's crust is very heterogeneous. Thus, rocks in a generalized form are aggregates of more or less constant chemical composition. These are independent geological bodies. They mean a clearly defined area of the earth's crust, having within its boundaries the same origin and age.
Rocks by group
1. Igneous. The name speaks for itself. They arise from cooled magma flowing from the mouths of ancient volcanoes. The structure of these rocks directly depends on the rate of lava solidification. The larger it is, the smaller the crystals of the substance. Granite, for example, was formed in the thickness of the earth's crust, and basalt appeared as a result of the gradual outpouring of magma onto its surface. The variety of such breeds is quite large. Looking at the structure of the earth's crust, we see that it consists of 60% igneous minerals.
2. Sedimentary. These are rocks that were the result of the gradual deposition of fragments of certain minerals on land and the ocean floor. These can be loose components (sand, pebbles), cemented components (sandstone), remains of microorganisms (coal, limestone), or products of chemical reactions (potassium salt). They make up up to 75% of the entire earth's crust on the continents.
According to the physiological method of formation, sedimentary rocks are divided into:
- Clastic. These are the remains of various rocks. They were destroyed under the influence natural factors(earthquake, typhoon, tsunami). These include sand, pebbles, gravel, crushed stone, clay.
- Chemical. They are gradually formed from aqueous solutions one or another minerals(salt).
- Organic or biogenic. Consist of the remains of animals or plants. These are oil shale, gas, oil, coal, limestone, phosphorites, chalk.
3. Metamorphic rocks. Other components can be converted into them. This occurs under the influence of changing temperature, high pressure, solutions or gases. For example, you can get marble from limestone, gneiss from granite, and quartzite from sand.
Minerals and rocks that humanity actively uses in its life are called minerals. What are they?
These are natural mineral formations that affect the structure of the earth and the earth's crust. They can be used in agriculture and industry as in natural form, and undergoing processing.
Types of useful minerals. Their classification
Depending on their physical state and aggregation, minerals can be divided into categories:
- Solid (ore, marble, coal).
- Liquid (mineral water, oil).
- Gaseous (methane).
Characteristics of individual types of minerals
According to the composition and features of application, they are distinguished:
- Combustibles (coal, oil, gas).
- Ore. They include radioactive (radium, uranium) and noble metals (silver, gold, platinum). There are ores of ferrous (iron, manganese, chromium) and non-ferrous metals (copper, tin, zinc, aluminum).
- Non-metallic minerals play a significant role in such a concept as the structure of the earth's crust. Their geography is vast. These are non-metallic and non-combustible rocks. This Construction Materials(sand, gravel, clay) and chemical substances(sulfur, phosphates, potassium salts). A separate section is devoted to precious and ornamental stones.
The distribution of mineral resources on our planet directly depends on external factors and geological patterns.
Thus, fuel minerals are primarily mined in oil and gas bearing and coal basins. They are of sedimentary origin and form on the sedimentary covers of platforms. Oil and coal rarely occur together.
Ore minerals most often correspond to the basement, overhangs, and folded areas of platform plates. In such places they can create huge belts.
Core
The earth's shell, as is known, is multi-layered. The core is located in the very center, and its radius is approximately 3,500 km. Its temperature is much higher than that of the Sun and is about 10,000 K. Accurate data on chemical composition the core has not been obtained, but presumably it consists of nickel and iron.
The outer core is in a molten state and has even greater power than the inner one. The latter is subject to enormous pressure. The substances of which it consists are in a permanent solid state.
Mantle
The Earth's geosphere surrounds the core and makes up about 83 percent of the entire surface of our planet. The lower boundary of the mantle is located at a huge depth of almost 3000 km. This shell is conventionally divided into less plastic and dense top part(it is from this that magma is formed) and to the lower crystalline one, the width of which is 2000 kilometers.
Composition and structure of the earth's crust
In order to talk about what elements make up the lithosphere, we need to give some concepts.
The earth's crust is the outermost shell of the lithosphere. Its density is two times less than medium density planets.
The earth's crust is separated from the mantle by the boundary M, which was already mentioned above. Since the processes occurring in both areas mutually influence each other, their symbiosis is usually called the lithosphere. It means "stone shell". Its power ranges from 50-200 kilometers.
Below the lithosphere is the asthenosphere, which has a less dense and viscous consistency. Its temperature is about 1200 degrees. A unique feature of the asthenosphere is the ability to violate its boundaries and penetrate the lithosphere. It is the source of volcanism. Here there are molten pockets of magma, which penetrates the earth's crust and pours out to the surface. By studying these processes, scientists have been able to do a lot amazing discoveries. This is how the structure of the earth's crust was studied. The lithosphere was formed many thousands of years ago, but even now active processes are taking place in it.
Structural elements of the earth's crust
Compared to the mantle and core, the lithosphere is a hard, thin and very fragile layer. It is made up of a combination of substances, in which more than 90 chemical elements have been discovered to date. They are distributed heterogeneously. 98 percent of the mass of the earth's crust is made up of seven components. These are oxygen, iron, calcium, aluminum, potassium, sodium and magnesium. The oldest rocks and minerals are over 4.5 billion years old.
Studying internal structure the earth's crust, various minerals can be distinguished.
A mineral is a relatively homogeneous substance that can be found both inside and on the surface of the lithosphere. These are quartz, gypsum, talc, etc. Rocks are made up of one or more minerals.
Processes that form the earth's crust
The structure of the oceanic crust
This part of the lithosphere mainly consists of basaltic rocks. The structure of the oceanic crust has not been studied as thoroughly as the continental one. Plate tectonic theory explains that the oceanic crust is relatively young, and the most recent parts of it can be dated to the Late Jurassic.
Its thickness practically does not change over time, since it is determined by the amount of melts released from the mantle in the zone of mid-ocean ridges. It is significantly influenced by the depth of sedimentary layers on the ocean floor. In the most voluminous areas it ranges from 5 to 10 kilometers. This type The earth's shell belongs to the oceanic lithosphere.
Continental crust
The lithosphere interacts with the atmosphere, hydrosphere and biosphere. In the process of synthesis, they form the most complex and reactive shell of the Earth. It is in the tectonosphere that processes occur that change the composition and structure of these shells.
The lithosphere on the earth's surface is not homogeneous. It has several layers.
- Sedimentary. It is mainly formed by rocks. Clays and shales predominate here, and carbonate, volcanic and sandy rocks are also widespread. In sedimentary layers you can find minerals such as gas, oil and coal. All of them are of organic origin.
- Granite layer. It consists of igneous and metamorphic rocks that are closest in nature to granite. This layer is not found everywhere; it is most pronounced on the continents. Here its depth can be tens of kilometers.
- The basalt layer is formed by rocks close to the mineral of the same name. It is denser than granite.
Depth and temperature changes in the earth's crust
The surface layer warms up solar heat. This is the heliometric shell. It experiences seasonal temperature fluctuations. The average thickness of the layer is about 30 m.
Below is a layer that is even thinner and more fragile. Its temperature is constant and approximately equal to the average annual temperature characteristic of this region of the planet. Depending on the continental climate, the depth of this layer increases.
Even deeper in the earth's crust is another level. This is a geothermal layer. The structure of the earth's crust allows for its presence, and its temperature is determined by the internal heat of the Earth and increases with depth.
The temperature rise occurs due to the decay of radioactive substances that are part of rocks. First of all, these are radium and uranium.
Geometric gradient - the magnitude of the temperature increase depending on the degree of increase in the depth of the layers. This parameter depends on various factors. The structure and types of the earth's crust influence it, as well as the composition of rocks, the level and conditions of their occurrence.
The heat of the earth's crust is an important energy source. Its study is very relevant today.
