The average density of the rocks of the earth's crust is. The chemical composition of the earth's crust

The Earth Cora is of great importance for our life, for research our planet.

This concept is closely associated with other characterizing processes occurring inside and on the surface of the Earth.

What is the earth bark and where it is

The land has a holistic and continuous shell, which includes: earth bark, troposphere and stratosphere, which are the lower part of the atmosphere, hydrosphere, biosphere and anthroposphere.

They interact closely, penetrating each other and constantly exchanging with energy and substance. Earth crust is customary to call the external part of the lithosphere - solid shell of the planet. Most of its outer side covers the hydrosphere. On the rest, the atmosphere is smaller.

Under the crust of the Earth is a denser and refractory mantle. The conditional border is separated, called the name of the Croatian scientist Mochorovich. Its feature is in a sharp increase in the speed of seismic oscillations.

To get an idea of \u200b\u200bthe earth's crust, various scientific methods. However, obtaining specific information is possible only ways of drilling to a greater depth.

One of the tasks of this study was to establish the nature of the boundary between the upper and lower continental bark. The possibilities of penetration into the upper mantle with the help of self-heating capsules from refractory metals were discussed.

The structure of the earth's crust

Under the continents, its sedimentary, granite and basalt layers are distinguished, the thickness of which in the aggregate is up to 80 km. Mountain breeds, called sediment, were formed as a result of precipitation of substances on land and in water. They are located mainly by the formation.

• clay
• clay shale
• sandstones
• carbonate breeds
• breed of volcanic origin
• stone coal and other breeds.

The sedimentary layer helps learn deeper about natural conditions On the ground, which were on the planet in time immemorial. This layer may have a different thickness. In some places it may not be at all, in other, mostly large deepening, can be 20-25 km.

The temperature of the earth's crust

An important energy source for the inhabitants of the Earth is the warmth of its bark. Temperature increases as depicted into it. The closest to the surface is a 30-meter layer, referred to as heliometric, is associated with the warmth of the sun and fluctuates depending on the season.

In the following, thinner layer, which increases in the continental climate, the temperature is constant and corresponds to the indicators specific place Measurements. In the geothermal layer of the cortex, the temperature is associated with the inner heat of the planet and grows as it deepened 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 is on average rises by three degrees as the deposits for every 100 meters. In contrast to the continental part, the temperature under the oceans is growing faster. After the lithosphere, a plastic high-temperature shell is located, the temperature, which is 1200 degrees. It is called an asthenosphere. It has places with molten magma.

Penetrating into the earth's bark, the asthenosphere can pour the molten magma, causing the phenomena of volcanism.

Characteristic of the earth's crust

The earth bark has a weighing less than half a percent of the entire mass of the planet. It is an outer sheath of the stone layer, in which the movement of the substance occurs. This layer, which has a double density less than that of the Earth. Its thickness varies within 50-200 km.

The uniqueness of the earth's crust is that it can be continental and oceanic types. The continental cortex has three layers, the top of which is formed by sedimentary rocks. The oceanic bark is relatively young and its thickness varies slightly. It is formed due to the substances of the mantle from the oceanic ridges.

ground Bark Characteristics Photo

The thickness of the cortex layer under the oceans is 5-10 km. Its feature in constant horizontal and vibrational movements. Most of the bark represent basalts.

The outer part of the earth's crust is a solid planet shell. Its triggered is distinguished by the presence of moving areas and relatively stable platforms. Lithospheric plates move relative to each other. The movement of these plates can cause earthquakes and other cataclysms. The patterns of such movements are investigated by tectonic science.

Functions of the earth's crust

It is customary to include the main functions of the earth's crust:

• resource;
• geophysical;
• geochemical.

The first of them indicates the presence resource potential Earth. It is primarily a set of mineral reserves located in a lithosphere. In addition, the resource function includes a number of habitat factors providing human life and other biological objects. One of them is the tendency to form a solid surface deficit.

so you can not do. Save our land photo

Thermal, noise and radiation effects implement a geophysical function. For example, there is a problem of a natural radiation background, which ground surface Basically safe. However, in countries such as Brazil and India, it can one hundred times permissible. It is believed that its source is radon and its decay products, as well as some types of human activity.

Geochemical function is associated with problems chemical pollution, harmful to humans and other representatives of the animal world. Various substances with toxic, carcinogenic and mutagenic properties fall into the lithosphere.

They are safe when they are in the depths of the planet. Zinc, lead, mercury, cadmium, and other heavy metals extracted from them can be greater danger. In the recycled solid, liquid and gaseous form, they enter the environment.

What is the earth's bark

Compared to the mantle and the core of the Earth's bark is a fragile, hard and thin layer. It consists of a relatively lightweight substance, which includes in its composition of the order of 90 natural elements. They are contained in different places of lithosphere and with varying degrees Concentration.

The main are: silicon oxygen aluminum, iron, potassium, calcium, sodium magnesium. 98 percent of the earth's crust consists of them. Including about half of the oxygen, over a quarter - silicon. Thanks to their combinations, such minerals are formed as a diamond, gypsum, quartz, etc. Multiple minerals can form a rock formation.

• A superhupatic well on the Kola Peninsula made it possible to get acquainted with samples of minerals from a 12-kilometer depth, where rocks close to granites and clay slates were found.
• The largest thickness of the bark (about 70 km) is revealed under mountain systems. Under flat sections, it is 30-40 km, and under the oceans - only 5-10 km.
• A significant part of the crust forms an ancient low-plate upper layer consisting mainly of granites and clay shale.
• The structure of the earth's crust resembles the bark of many planets, including on the moon and their satellites.

The Earth is part of the solar system, is at a distance of 149.8 million kilometers from the Sun and is the fifth in size among other planets.

A little about planet Earth

Speed \u200b\u200bof circulation heavenly Body Around the sun is 29.765 km / s. Full turnover it is done for 365.24 sunny day.

Our Planet Earth has one satellite. This is the moon. It is in the orbit of our planet at a distance of 384,400 km. Mars has two satellites, and Jupiter - sixty-seven. The average radius of our planet is 6371 km, while it looks like an ellipsoid, a little flattened at the poles and elongated by equator.

Mass and density of the Earth

Its mass is 5.98 * 1024 kg, and the average density of the land is 5.52 g / cm 3. At the same time, this indicator in the earth's crust is within 2.71 g / cm 3. It follows from this that the density of the planet Earth is significantly increased towards depth. This is due to the feature of its structure.

For the first time, the average density of the Earth was determined by I. Newton, which calculated it in the amount of 5-6 g / cm 3. Its chemical composition is similar to the planets of the earth group, such as Venus and Mars and partly Mercury. Earth composition: iron - 32%, oxygen - 30%, silicon - 15%, magnesium - 14%, sulfur - 3%, nickel - 2%, calcium - 1.6% and aluminum - 1.5%. The remaining elements in the amount account for about 1.2%.

Our Planet - Blue Traveler in Space

Finding the Earth near the Sun influences the presence of certain chemical substances both in a liquid and gaseous state. This is diverse, an atmosphere, a hydrosphere and a lithosphere formed. The atmosphere mainly consists of a mixture of gases: nitrogen and oxygen 78% and 21%, respectively. As well as carbon dioxide - 1.6% and an insignificant amount of inert gases, such as helium, neon, xenon and others.

The hydrosphere of our planet consists of water and occupies 3/4 of its surface. The Earth is the only planet of the solar system known for today, which has a hydrosphere. Water played a decisive role in the process of living on earth. Due to its circulation and high heat capacity, the hydrosphere balances climatic conditions on different latitudes and forms the climate on the planet. Oceans, rivers and solid part of our planet consist of sedimentary formations, granite and basalt layer.

and its structure

The land, as well as the other planets of the earth's group, has a layered indoor structure. In her center is the kernel.

Further, a mantle follows, which occupies a significant part of the volume of the planet, and then the resulting layers differ in their composition among themselves. For the existence of our planet, over 4.5 billion years, more heavy breeds and elements under the influence of gravity have penetrated further and further into the center of the Earth. Other elements, more lungs, remained closer to its surface.

The complexity and inaccessibility of the study of subsoil

A person is very difficult to penetrate deep into the earth. One of the deepest wells drilled on the Kola Peninsula. Its depth reaches 12 kilometers.

At the same time, the distance from the surface to the center of the planet is more than 6,300 kilometers.

We use indirect research tools

Because of this, the depths of our planet, located at a considerable depth, are analyzed by the results of seismic intelligence. Every hour at different points of the Earth is about ten oscillations of its surface. Based on the data obtained, thousands of seismic stations conduct a study of the propagation of waves during the earthquake. These oscillations are distributed in the same way as circles on water from an abandoned object. When the wave penetrates into a more compacted layer, its speed changes dramatically. Using the data obtained, scientists were able to identify borders internal shells Our planet. The structure of the Earth is distinguished by three main layers.

Earth bark and its properties

Top is the earthly bark. Its thickness can vary from 5 kilometers in oceanic areas up to 70 kilometers in the mountainous areas of the mainland. In relation to the whole planet, this shell is not the thicker of the eggshell, and underground fire is raging. Echoes of deep processes occurring in the depths of the Earth, which we observe in the form of eruptions of volcanoes and earthquakes, cause great destruction.

The Earth Cora is the only layer that is available to people for life and full-fledged research. The structure of the earth's crust under the continents and the oceans is different.

The continental earth bark occupies much smaller, but has a more complex structure. It contains under the sedimentary layer an external granite and lower basalt layers. IN continental Kore There are more than a long rock, whose age is almost two billion years.

Thin thin, only about five kilometers, and contains two layers: lower basalt and upper sediment. The age of oceanic rocks does not exceed 150 million years. This layer may exist life.

Mantle and what we know about her

A layer, referred to as the mantle, occurs under the crust. The boundary between her and the bark is rather sharply designated. She is named a layer of Mochorovich, and it can be found at a depth of about forty kilometers. The Mochorovich border consists mainly of basalt and silicates that are in solid state. The exception is some "lava pockets", which are in liquid form.

The thickness of the mantle is almost three thousand kilometers. The same layers were found on other planets. At this border, a clear increase in seismic velocities from 7.81 to 8.22 km / s is occurring. The land mantle is divided into the upper and lower components. The border between these geospheres serves as a layer of Galicin, which is at a depth of about 670 km.

How was knowledge about the mantle?

At the beginning of the 20th century, the border of Mochhorovich was intensively discussed. Some researchers believed that it was there that a metamorphic process occurs, in which rocks with high density are formed. Other scientists explained a sharp increase in the speed of movement of seismic waves by changing the content of the composition of rocks from relatively light to more heavy types.

Now this point of view is considered the main in understanding and methods of research on the processes occurring inside the planet. Itself is directly unavailable for direct studies due to a deep lounge, and it does not go to the surface.

Therefore, the main information is obtained by geochemical and geophysical methods. In general, reconstruction through existing sources is a very difficult task.
Mantle receiving radiation from the center, heating from 800 degrees upstairs up to 2000 degrees near the kernel. It is assumed, that the substance of the mantle dwells in continuous movement.

What is the density of land in the area of \u200b\u200bthe mantle?

The density of the land within the mantle reaches about 5.9 g / cm 3. Pressure is growing with increasing depth and can reach 1.6 million atmospheres. In the matter of determining the temperature in the mantle, the opinions of scientists are not unambiguous and fairly contradictory, 1500-10000 degrees Celsius. These are the existing opinions in scientific circles.

The closer to the center, the hotter

In the center of the Earth, the kernel is located. Its upper part is at a depth of 2900 kilometers from the surface (external kernel) and is about 30% of the total mass of the planet. This layer has the properties of the liquid and electrical conductivity. About 12% of sulfur and 88% iron contains in itself. On the border of the nucleus and the mantle increases dramatically the density of the Earth and reaches about 9.5 g / cm 3. At a depth of approximately 5,100 km recognize its inner part, the radius of which is about 1260 kilometers, and the mass is 1.7% of the total mass of the planet.

The pressure in the center is so huge that iron and nickel that should be liquid are in a solid state. According to scientific researchThe center of the Earth is a place with super-extremal conditions with a pressure of 3.5 million atmospheres and temperatures above 6000 degrees.

In this regard, the iron-leaving alloy does not go into liquid stateDespite the fact that the melting point of such metals is 1450-1500 degrees Celsius. Due to the gigantic pressure in the center, the mass and density of the Earth are quite huge. One cubic decimeter of the substance weighs about twelve and a half kilograms. This is a unique and only place where the density of the planet is significantly higher than in any other of its layer.

Reveal all the mechanisms of interaction inside the ground would not only be interesting, but also useful. We would understand the formation of various minerals and their location. Perhaps it would have fully understood the mechanism of earthquakes, which would have given the opportunity to definitely warn them. Today they are unpredictable and bring many victims and destruction. The exact knowledge of the convection of the flows and their interaction with the lithosphere may be shedding the light on this problem. Therefore, the future scientists will have a long, interesting and useful work for all mankind.

The chemical composition of the Earth (Fig. 1) is similar to the composition of other planets of the earth group, such as Venus or Mars.

In general, elements such as iron, oxygen, silicon, magnesium, nickel prevail. The content of light elements is small. The average density of the substance of the Earth is 5.5 g / cm3.

The internal structure of the land of reliable data is very little. The earth consists of the earth's crust, mantle and core.

Fig. 1. Chemical composition of the Earth

Fig. 2. Internal structure Earth

Core Located in the center of the Earth, its radius is about 3.5 thousand km. The kernel temperature reaches 10,000 K, i.e. it is higher than the temperature of the outer layers of the Sun, and its density is 13 g / cm3 (compare: water - 1 g / cm3). The core presumably consists of iron and nickel alloys.

The external core of the Earth has a greater power than the internal (radius of 2,200 km) and is in a liquid (molten) state. The inner core is susceptible to colossal pressure. The substances that lay it are in a solid state.

Mantle- The geosphere of the Earth, which surrounds the core and is 83% of our planet. The lower border is located at a depth of 2900 km. The mantle is divided into a less dense and plastic top (800-900 km), from which Magma is formed (translated from Greek means "thick ointment"; this is the molten substance of the earth's subsoil - the mixture chemical compounds and elements, including gases, in a special semi-liquid state); And the crystal lower, tire about 2000 km.

Earth's crust - The outer shell of the lithosphere. Its density is about two times less than the average density of the Earth, 3 g / cm3.

From the mantle, the earth boron separates the border of Mochorovichich (it is often referred to as the moss boundary), which is characterized by a sharp increase in the velocities of seismic waves. It was installed in 1909. Croatian scientist Andrei Mochorovichich (1857-1936).

Since the processes occurring in the upper part of the mantle affect the movement of the substance in the earth's crust, they are combined under the general name of the lithosphere (stone shell). Lithosphere power ranges from 50 to 200 km.

Below the lithosphere is an asthenosphere - less solid and less viscous, but more plastic shell with a temperature of 1200 ° C. It can cross the border of Mokho, embedded in the earth's bark. Asthenosphere is a source of volcanism. It contains the foci of molten magma, which is embedded in the earth's bark or poured onto the earth's surface.

2. Litosphere and its structure

Lithosphere is a solid sheath of the Earth, consisting of the earth's crust and top of the mantle (from Greek. Lithos - stone and sphaira - ball). It is known that there is a close relationship between the lithosphere and the land mantle. The power of the lithosphere is an average of 70 to 250 km.

Lithosphere - This is the outer shell of the "solid" land.

The earth's crust and upper (solid) part of the mantle form a lithosphere. It is a "ball" from solid matter By a radius of about 6400km. Ground Cora - the outer shell of the lithosphere. It consists of a sedimentary, granite and basalt layers. Different oceanic and mainland terrestrial bark. As part of the first there is no granite layer. The maximum thickness of the earth's crust is about 70 km - under mountain systems, 30-40 km - under the plains, the most subtle crust - under the oceans, only 5-10 km.
The rest of the part we call the internal lithosphere, which also includes the central part called the kernel. ABOUT internal layers We almost do not know the lithosphere, although their share accounts for almost 99.5% of the entire mass of the Earth. They can be studied only with the help of seismic studies.

The thickness of the lithosphere varies from 50 km (under the oceans) to 100 km (under the mainland). The triggered lithosphere is represented by its large blocks - lithospheric plates separated from each other deep tectonic faults. Lithospheric plates are moving in a horizontal direction at an average speed of 5-10 cm per year.

Form of the Earth.

The form of the earth is close to the ellipsoid, fightened by the poles and stretched in the equatorial zone. Middle Earth Radius 6371,032 km, Polar 6356,777 km, Equatorial 6378,160 km. Earth mass 5,976 · 1024 kg, average density 5518 kg / m3.

Earth density.

The density of the Earth was first defined by I. Newton in 1736 within 5-6 g / cm 3. Subsequent, more accurate, Dali Definitions middle density 5.527 g / cm 3. This value significantly exceeds the density of the upper horizons of the earth's crust, which, on the basis of numerous measurements of the densities of the rock surface, can be determined more or less accurately. In tab. The average density of full-rolled erupted rocks (according to R. A. Dali) is given.

Based on the average densities of rocks (it is believed that 18% of the Earth Cora is of 95% of the erupted, 4% of metamorphic and 1% of sedimentary rocks.), The glories of the earth's bark, the density of the "granite layer" of the earth's crust takes equal to 2.7 g / cm 3, "basalt layer" - 2.9 g / cm 3, "basalt layer" of the oceanic cortex - from 3.0 to 3.1 g / cm 3, and the upper part of the subcortical layer (mantle) - 3.3 g / cm 3 (taking into account the pressure at a depth of 30-40 km).

The strength of the gravity of the earth.

The strength of gravity is due to the total mass of the Earth. Therefore, all oscillations in the mass distribution in vertical cuts should be reflected in the amount of gravity. In this regard, it would be natural to expect more or less significant impact of the relief on the distribution of gravity on the earth's surface. In particular, on the mainland, the rocks distinctly expressed in the relief of rocks, the strength of gravity would have to be greater than on the oceans, the surface of which lies at a lower plasterometric level and the upper horizons are composed with a 4-kilometer water layer, significantly less dense than mountain breed of continents. However, from comparison of fields of gravity of oceans and mainland, it follows that in the absolute value of the abnormality of gravity on those and others are almost equal. Some more significant, but completely understandable and natural changes in gravity on Earth are caused by polar compression and centrifugal power, developing during the rotation of the planet and directed at the equator to the side, the opposite strength of gravity (the amount of gravity increases from the equator to the poles by 0.5%). The strength of gravity is also changing under the influence of the attraction of the moon and the sun ("lunar-solar gravity variations"), which affects not only any body on the earth's surface, but also on the whole ground, causing tidal deformations that vary not only liquid, but also solid terrestrial shell.

The shell of the globe.

Earth's crust - External solid shell of the Earth (geosphere). Below is a mantle that is characterized by the composition and physical properties - It is more dense, contains mainly refractory elements. Separates the bark and the mantle border of Mochorovichich, or abbreviated Mocho, on which there is a sharp increase in the speeds of seismic waves. From the outside, most of the cortex is covered with hydrosphere, and the smaller is under the influence of the atmosphere.

Magnetic properties Earth.

Magnetic field of land. Most of the planets of the solar system to one degree or another possess magnetic fields. Descending the dipole magnetic moment in the first place, Jupiter and Saturn, and the land, Mercury and Mars follow them, and in relation to the magnetic moment of the Earth, the value of their moments is 20,000, 500, 1, 3/5000 3/10000. The dipole magnetic moment of the Earth in 1970 was 7.98 · 10 25 Gs / cm 3 (or 8.3 × 10 22 AM 2), decreasing in a decade by 0.04 · 10 25 Gs / cm 3. The average field strength on the surface is about 0.5 e (5 · 10 -5 T.). In the form of the main magnetic field of the Earth to the distance less than three radii close to the field of an equivalent magnetic dipole. Its center is shifted relative to the center of the Earth towards 18 ° C.Sh. and 147.8 ° C. D. The axis of this dipole is inclined to the axis of the rotation of the Earth by 11.5 °. On the same angle, geomagnetic poles will be distinguished from the corresponding geographic poles. At the same time, the southern geomagnetic pole is in the northern hemisphere. It is currently located near the Northern Geographical Pole of the Earth in Northern Greenland. Its coordinates J \u003d 78,6 + 0.04 ° T S.Sh., L \u003d 70.1 + 0.07 ° T 4, where T is the number of decades from 1970. At the ambulance of the magnetic pole J \u003d 75 ° Yu.Sh., L \u003d 120.4 ° V.D. (in Antarctica). Real magnetic power lines magnetic field The lands are on average close to the power lines of this dipole, differing from them by local irregularities associated with the presence of magnetized rocks in the crust. As a result of century variations, the geomagnetic pole precesss relative to the geographical pole with a period of about 1200 years. On the large distances The magnetic field of the earth is asymmetrically. Under the action of plasma flow (solar wind), the magnetic field of the Earth is distorted and acquires a "loop" in the direction from the Sun, which extends hundreds of thousands of kilometers, going beyond the orbit of the moon.

Thermal properties of the Earth.

The main thermal sources in the land mantle are the heat reserve remaining since the time of the early melted state, and the heat forming during the decay of radioactive elements. The averaged content of radioactive elements in the earth's crust does not exceed the thousandth fractions of the grams per kilogram of rock, but the heat generated by them has a significant effect on the thermal properties of the Earth as a whole. If the radioactive substances would be found in the same proportions as in the surface rocksthen the temperature in depths would not have fallen, but to grow, and the mantle would be completely liquid, which contradicts the modern representation

the important magnitude of the heat flux from the kernel in the mantle is largely determined by the convective processes occurring in the nucleus, the intensity of which in turn affects the magnitude of the magnetic field generated in it.

The pressure of the globe.

In general, several atmospheric pressure belts are formed on the globe. At the equator, the intense heated sun, it is constantly lowered. Here, the air heated from the earth's surface rises and spreads towards tropical latitudes. Height is cooled, lowered down, creating in the tropics increased pressure. Above the poles, the temperature is constantly low, here the cold air is lowered and compacted, the air from moderate latitudes comes into these areas. Above the poles are installed high pressure, and low-temperate latitudes - low.

High and low pressure belts are not distributed above the surface of the Earth with smooth stripes, because the continents and oceans, by different absorbing and giving sunny heatMounted on the globe unevenly.

Introduction

Three outer shells of land, differing in phase state, is a solid earthbow, a liquid hydrosphere and a gas atmosphere - are closely related to each other, and each of them penetrates the limits of others. Ground waters permeate the upper part of the earth's crust, a significant amount of gases is not in the atmosphere, but dissolved in the hydrosphere and fills emptiness in the soil and rocks. In turn, water and small solid mineral particles saturate the lower layers of the atmosphere.

The outer shells are associated not only spatially, but also genetically. The origin of the shells, the formation of their composition and its further evolution is interrelated. Currently, this connection is largely due to the fact that the outer part of the planet is covered by the geochemical activities of the living matter.

The masses of the shells differ greatly. The mass of the earth's crust is estimated at 28.46 × 10 18 t, the oceans - 1.47 × 10 18 tons, the atmosphere - 0.005 × 10 18 tons. Consequently, in the earth's crust is the main reserve of chemical elements, which are involved in migration processes under the influence of living matter. The concentrations and distribution of chemical elements in the earth's crust have a strong effect on the composition of the living organisms of sushi and the entire living matter of the Earth.

Considering the problem of the composition of the living matter, V.I. Vernadsky noted: "... The chemical composition of organisms is closely connected with the chemical composition of the earth's crust; Organisms are escaped to it. "

Chemists and petrographers starting with the second halves XIX. in. We studied the chemical composition of rocks by the methods of weight and voluminous chemical analysis. Summing up the results of numerous thunder analyzes, F. Clark showed that eight chemical elements prevail in the earth's crust: oxygen, silicon, aluminum, iron, magnesium, calcium, potassium and sodium. This main conclusion was repeatedly confirmed by the results of subsequent studies. The methods of chemical analysis used in the XIX century, the determination of low concentrations of elements was impossible. They needed fundamentally different approaches.

The powerful impetus to the study of chemical elements with very low concentration in the substance of the earth's crust gave the use of a more sensitive method - spectroscopic analysis. New facts allowed V.I. Vernadsky formulate the principle of "everyuality" of all chemical elements. In the report at the XII congress of Russian naturalists and doctors in December 1909, he stated: "In every drop and dust the substance on the earth's surface, as the subtlety of our studies increases, we open up all new and new elements ... in the sand or drop, as In the microcosm, the overall composition of the space is reflected.

The idea of \u200b\u200b"everyuality" of chemical elements for a long time caused alertness even from major scientists. This was due to the fact that the elements contained in the amount below the level of sensitivity of the method were not detected during the analysis. The illusion of their complete absence was created, which was reflected on the terminology. In geochemistry, the terms arose rare elements (Dieseltenelemenenn.; RareElements- English), frequency (Diehaufigkeit - it.) detection. In fact, there is not a real rarity or small frequency of occurrence of the element during analyzes, and its low concentration in the studied samples, which cannot be determined by insufficiently sensitive analysis methods.

The low sensitivity of the method often did not allow to determine the amount of the element, but only to state the presence of its "traces". Since then, in geochemical literature, the term is widely used? Used by V.M. Goldshmidt and his colleagues in the 1930s: elements traces (Diespurelemente.; TraceElements- English; DeselementStraceS- Fr.).

As a result, the efforts of scientists from different countries in the 20s. XX century There was a general idea of \u200b\u200bthe composition of the earth's crust. The average values \u200b\u200bof the relative content of chemical elements in the earth's crust and other global and space systems famous geochemist A.E. Fersman suggested calling clarki. In honor of the scientist who outlined the way to quantify the distribution of chemical elements.

Clark is a very important value in geochemistry. Analysis of Clark values \u200b\u200ballows to understand many patterns of distribution of chemical elements on Earth, in Solar system and accessible to our observations of the universe. Clarki chemical elements of the earth's crust differ in more than ten mathematical orders. Such a significant quantitative difference should be reflected in the qualitatively unequal role of two groups of elements in the earth's crust. This is most pronounced in the fact that the elements of the first group contained in relatively large quantitiesForming independent chemical compounds, and the elements of the second group with small Clarks are mainly sprayed, scattered among chemical compounds of other elements. The elements of the first group are called the main Elements of the second - scattered. Their synonyms B. english language are minorelements, rareelements that are most used by synonymous tracelements. The conditional boundary between the groups of the main and scattered elements in the earth's crust can serve as the value of 0.1%, although Clarks most of the scattered elements are significantly less and measured by thousandth and smaller percentages. The concept of the state of scattering the chemical elements, as well as about their "everybody," was introduced into science in V.I. Vernadsky.

The full chemical composition of the upper, so-called granite, the layer of the continental block of the earth's crust is given in Table. 1.1.

Table 1.1 Clarki Chemical Elements of the Granite Layer of the Corn of Continents

To form any chemical compound, the concentration of the source components is not less than the minimum, below which the reaction is not possible. Therefore, in the earth's crust, chemical compounds of the main elements with high Clarks are dominated. Despite the fact that the total number of natural chemical compounds - minerals - Makes up 2-3 thousand species, the number of minerals forming common rocks is small. More than 80% of the mass of the earth's crust is represented by silicates of aluminum, iron, calcium, magnesium, potassium and sodium; About 12% is silicon oxide. All these minerals have a crystalline structure that determines general features crystalochemistry of the earth's crust.

V.M. Goldshmidt showed that the silicate composition and the crystalline structure of the earth's crust are very important for the distribution of non-main, scattered elements. According to the Goldshmidt concept in crystalochemical structures, ions behave like rigid areas (solid balls). Therefore, the radius of each ion is considered as a constant value.

The main feature of ions in crystalochemical structures is that the radii of negatively charged ions (anions) is significantly more radii of positively charged ions (cations). Imagine anions in the form of large balls, and the cations are in the form of small. Then the model of the crystalline substance with the ion type of communication will be space filled with tightly adjacent large balls - anions, between which small balls should be placed - cations. According to Goldshmidt's representations, this frame plays the role of a kind of geochemical filter that promotes the differentiation of chemical elements by the magnitude of their ions. Not any elements with the necessary valence can enter into a specific crystal chemical structure, but only those whose ions have the appropriate size of the radii.

The formation of common minerals is accompanied by a kind of sorting of scattered elements. To explain this process, we turn to the common mineral - a field swop. Its crystal chemical structure is formed by groupings consisting of three silicon cations and one aluminum, each of which is associated with four oxygen anions. The grouping as a whole is a complex anion, where eight oxygen ions, three silicon and one aluminum. This creates one negative charge that is balanced by a monovalent potassium cation. As a result, there is a three-chamber structure, the composition of which corresponds to the formula K.

The magnitude of the radius of potassium ion is 0.133 nm. Its place in the structure can only occupy a cation with a close amount of radius. Such is the bivalent barium cation, the radius of which is 0.134 nm. Barium is less common than potassium. It is usually present in the form of a minor impurity in the field spatts. Only in special cases Its significant concentration is created and a rare mineral is Clean (barium field spat).

Similarly, in common minerals and rocks, chemical elements are selectively detained, the concentration of which is not as large for the formation of independent minerals. Mutual replacement of ions in the crystal structure due to the proximity of their radii is called isomorphism. This phenomenon was discovered yet in early XIX. c., but its value for the global differentiation of scattered chemical elements is established only later than a century.

As a result of isomorphism, the scattered elements are naturally concentrated in certain minerals. Field spaspers serve as barium carriers, strontium, lead; Olivina - Nickel and Cobalt; Zircon - Hafnesium, etc. Elements such as rubidium, rhenium, hafnium, do not form independent compounds in the lithosphere and are completely scattered in the crystalochemical structures of the minerals of the hosts.

Isomorphic substitutions are not the only form of finding scattered elements. The scattering phenomenon in the earth's crust is manifested in different forms on different level Dispersion.

The most coarse-oversized form of scattering are well omitted, very small (usually less than 0.01 - 0.02 mm in the diameter) accessor minerals. They form mechanical inclusions in breed-forming minerals (Fig. 1.1).

Fig. 1.1 Inclusion of accessor apatite (1) and zircon (2) in the beans of the field spat. Transparent grief, increase 160 '

The maintenance of the Accessories is very minor, but the concentration of scattered elements in them is so high that these elements form independent connections. In crystalline rocks, zrkon zr, rutile, less commonly Anatas and Broquit, having the same type of TiO 2, Apatite Ca 5 [PO 4] 3 F, Magnetite Fe 2+ Fe 2 3+ O 4, Ilmenit Fetio 3, Monocite SERO 4, Xenotim YPO 4, Cassiterite SNO 2, Chrome EEC 2 O 4 and other weed apatitis (7) and minerals of the spinel group, Colombite Group minerals (Fe, Mg) (NB, TA) 2 O 6, etc.. Content of Aquassorian in some Pody-forming minerals, especially in mica, rather noticeable.

In some minerals, mainly among sulfides and similar compounds, the so-called solid decay structures of the solid solution are widespread - small allocations of the mineral impurity in the substance of the master mineral. According to their example, the "emulsion enclosure" of the CuFes 2 chalcopyrite and the Cu 2 FESNS 4 bed to the ZNS are sequerate, thin plate allocations of Fetio 3 in the FE 2+ Fe 2 3+ O 4 magnetite, minor seals of silver minerals in the PBS ganitis. As a result, a tangible admixture of silver is present in the lead sulfide, in the sulfide of copper - admixture of tin, in magnetite - a mixture of titanium.

The use of polarization microscope and transparent grinds made it possible to detect in minerals not only solid inclusions, but also micro-emptiness filled with residues of solutions from which crystallization was carried out (Fig. 1.2).

Fig. 1.2. Micro-foam in quartz: 1 - Crystal Sylvina; 2 – Crystal Galita; 3 – gas bubble; 4 – Liquid phase. Transparent grief, increase 900 '

This phenomenon for the first time specifically considered in 1858, the founder of the optical petrography of Sorbi, to date, is comprehensively studied. Micro-foam in minerals typically contain liquid and gas phases, sometimes small crystals are added to them. The problem of liquid inclusions was thoroughly analyzed by W. Newhouse, which noted the presence of heavy metals in fluids (up to several percent).

Some of the impurities of scattered elements, easily extracted from finely broken monomineral samples, is associated with liquid inclusions. N.P. Ermakov (1972), having studied microwave from the fluorite, found N × 10 -1% zinc in them, manganese, N × 10 -2% barium, chromium, copper, nickel and lead, N × 10 -3% titanium. In the future, other scattered elements were found in liquid inclusions.

At the same time, a careful analysis of monomineral samples and the use of electronic sensing has shown that, without exception, the breeding minerals contain scattered elements in so highly dispersed form that they cannot be detected not only with optical, but also electron microscopy. In this case, there is scattering of elements at the level of ions and molecules. Forms of such scattering are not limited to previously discussed with the phenomena of isomorphism. Numerous cases of the presence of chemical elements in minerals that have no connection with isomorphism are known.

The results of many thousands of analyzes performed in different countries Over the past 50 years, it suggests that all breeding minerals are carriers of scattered elements. It is in them that focuses the bulk of the scattered elements contained in the earth's crust. Knowing the content of media minerals and the concentration of scattered elements in them, you can calculate the balance within a particular rock formation.

When studying the granites Tien Shan, it was found that in quartz, despite the insignificant lead concentration, more than 5% of the entire mass of this metal contained in the breed (Table 1.2) was concluded.

Table 1.2. Distribution of lead in minerals, granite granites Jumgol

It is impossible to assume the isomorphic entry of lead, zinc or other metal into a quartz structure formed by a combination of silicon and oxygen ions. Meanwhile, the quartz serves as a carrier of many scattered elements. A special method of assessing the potential rudopy of rocks has been developed and lived in content in quartz of lithium, rubidium, boron.

With experimental study of the strength of fixing scattered metals in breed-forming minerals, it was found that in the treatment of finely ground mineral mass by sequential portions of weak acid-alkaline solvents, a significant portion of metals are easily extracted at the first extraction, and this extraction is not accompanied by the destruction of the crystal chemical structure of minerals. With further processing, the number of extracted metals is sharply reduced or stopped at all. This made it possible to express the assumption that part of the scattered elements is not included in the actual crystalochemical structure, but is confined to defects of real crystals. Defects are all sort of cracks, and so small, which is not detected by an optical microscope. The ease of extracting scattered metals is explained by the fact that they are associated with the surface of the mineral carrier by the sorption forces. In the breed-forming silicates, this form of finding scattered metals is 10 - 20% of the entire mass of multiple metals. In particular, the fragilely connected form of lead in the granites of Tien Shan ranges from 12 to 18% of the entire mass of the scattered element.

The following forms of finding scattered elements in the crystalline of the earth's crust can be distinguished:

I. Micromineralogical forms:

1. Elements included in accessor minerals.

2. The elements contained in microscopic discharges as a result of the decay of solid solutions.

3. Elements that are in the inclusions of residual solutions. P. Nevinineralogical forms:

4. Elements sorbed by the surface of real crystals defects.

5. Elements included in the structure of the carrier mineral according to the laws of isomorphism.

6. Elements located in the structure of the carrier mineral in an unordered state.

The combination of discussed forms of finding scattered elements varies greatly depending on many factors. Accordingly, the total content of the scattered element in different parts of the earth's crust is also changing.

3. Features of the distribution of chemical elements in the earth's crust

Varing the content of the element in different samples is due to many independent reasons. When the distribution of the value is determined by a sufficiently large number of approximately equal and mutually independent causes, then it obeys the so-called normal law of Gauss. Its graphic expression is a curve with symmetrical branches on both sides of the maximum ordinate. With a normal distribution, the most likely value serves arithmetic average which coincides with the most common values \u200b\u200b- fashion. Stretching symmetric curve along the abscissa axis, i.e. scattering values \u200b\u200bin a large and smaller side of the fashion characterized medium quadratic deviation but.

Normal distribution can also manifest itself for the most magnitude, but for its logarithm (logarithmically normal, or logon, distribution law). In this case, the fashion coincides with the average geometric, and the variation variation is characterized by logarithm A.

In 1940 N.K. Razumovsky empirically found that the content of metals in the ores corresponds to logarithmically normal distribution. L.X. Arena in 1954, having finished extensive material, regardless of Razumovsky found that the distribution of scattered elements in magmatic rocks is approximated by logarithmically by normal law. Numerous facts indicate that the distribution of elements with high Clarks is usually subject to a normal law, and diffused - logon. This once again confirms the fundamental difference in the main and scattered elements.

With high variability of low-flame elements related to their ability to high degree Concentration. The maximum degree of concentration of the main elements is 10 - 20 times with respect to their Clark, and for multiple elements - hundreds and thousands of times more. For example, in the ores of industrial deposits, the degree of lead concentration, nickel, tin, chromium is 1000 × p.

Speaking about the tremendous masses of heavy metals focused in ore deposits, it should be remembered that these masses are an insignificant part of the total number of metals scattered in the earth's crust. In particular, the global reserves of ores zinc, copper, lead, nickel constitute only thousandth fractions of the percentage of these metals, scattered in the upper kilometer layer of the earth's crust of the continents.

RUD deposits are associated with surrounding rocks by gradual transitions. Ore bodies are as it were in a case of gradually decreasing concentrations of metals. Such educations were called oreols scattering Primary, syngenetic ore hacides arise simultaneously with ore bodies and as a result of the same processes. They have a variety of configuration, depending on the geological structure, the composition of the enclosing rocks and the conditions of ore formation.

In the ores, along with one or more of the main ore-forming elements, there are related elements, the concentration of which is also increased, but not as important as the main ones. Elements satellites often form isomorphic substitutions of the main. For example, cadmium is constantly contained in zinc ores, in a smaller number of India, Gallium, Germany. In copper-nickel ores there is a significant admixture of cobalt, in smaller quantities - Selena and Tellur. All related elements are also scattered around ore bodies. Possessing unequal geochemical mobility, they form transition zones of different lengths. As a result, the composition and structure of the scattering halois are very complex.

The average content of the chemical element is the norm - geochemical background - for this type breeds in a certain area. On a geochemical background allocated geochemical anomalies - Plots of rocks with an increased concentration of scattered elements. If they are connected with the deposits of ore, then these are the scattering halis. If the concentration of metals do not reach the cost of ore, then such anomalies are called false. Using statistical processing of mass analytical data, it is possible to detect natural changes in the magnitude of the geochemical background in space and reveal geochemical provinces. Within the provinces, the mountain rocks of the same type have a decorated statistical parameters, primarily the values \u200b\u200bof the average content of one or more scattered elements. The average content of certain elements in the same type of rocks of different geochemical provinces can vary greatly (several times). In this case, the chemical composition of these rocks, determined by the content of the main elements, remains the same or has very weak differences. For example, in the granites of different provinces having almost the same amount of silicon, aluminum, iron, potassium, tin content, lead, molybdenum, uranium may vary 2-3 times.

The stated material indicates the uneven distribution of scattered elements in the earth's crust. Therefore, along with the definition of Clarks, i.e. The magnitudes of the average concentration of elements in the earth's crust as a whole, it is necessary to take into account their ability to concentrate or dissipate in various objects - different types of rocks or in the same type of rocks, but located in different geochemical provinces, in ores, etc. To quantify the heterogeneity of chemical elements in the earth Korea, V.I. Vernadsky introduced a special indicator - clark concentration to to. Its numeric value characterizes the deviation of the content of the element in this amount from Clark:

To k \u003d a / k,

where BUT - maintenance of the chemical element in rock, ore, mineral, etc.;

TO - Clark of this element in the earth's crust. If Clark concentration is more than a unit, this indicates an element enrichment, if less - means a decrease in its content compared with the data for the earth's crust as a whole.

Change in the concentration of chemical elements in space, deviation from global or local geochemical norms, not separate cases, and feature geochemical structure of the earth's crust. It is very important for the composition of the photosynthetic sushi organisms, which form the bulk of the mass of the living agent of the Earth.

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