Occupies middle part North Asia. This is one of the large, relatively stable ancient blocks of the Earth's continental crust, which are among the ancient (pre-Riphean) platforms. Its foundation was formed in the Archaean, subsequently it was repeatedly covered by seas, in which a powerful sedimentary cover was formed. Several stages of intraplate magmatism have occurred on the platform, the largest of which is the formation of the Siberian traps at the Permian–Triassic boundary. Before and after the emplacement of the traps, there were sporadic outbursts of kimberlite magmatism that formed large diamond deposits.

Siberian platform it is limited by zones of deep faults - marginal seams, well-defined gravitational steps, and has polygonal outlines. Modern borders platforms took shape in the Mesozoic and Cenozoic and are well expressed in the relief. The western boundary of the platform coincides with the valley of the Yenisei River, the northern one - with the southern margin of the Byrranga mountains, the eastern one - with the lower reaches of the Lena River (Verkhoyansk marginal trough), in the southeast - with the southern tip of the Dzhugdzhur ridge; in the south, the boundary runs along the faults along the southern margin of the Stanovoy and Yablonovy ridges; then, going around from the north complex system faults of Transbaikalia and Baikal, descends to southern tip Lake Baikal; the southwestern boundary of the platform extends along the Main East Sayan Fault.

On the platform, the Early Precambrian, mainly Archean, basement and platform cover (Riphean-Anthropogenic) stand out. Among the main structural elements of the platform stand out: the Aldan Shield and the Leno-Yenisei Plate, within which the basement is exposed on the Anabar massif, Olenyok and Sharyzhalgay uplifts. Western part The plates are occupied by the Tungusskaya, and the eastern one by the Vilyui syneclise. In the south there is the Angara-Lena trough, separated from the Nyu depression by the Peledui uplift.

Geological history

1. During the Archean and the beginning of the Proterozoic, most of the basement of the East Siberian Platform was formed.
2. At the end of the Proterozoic (Vendian) and the beginning of the Paleozoic, the platform was periodically covered by a shallow sea, resulting in the formation of a thick sedimentary cover.
3. At the end of the Paleozoic, the Paleo-Ural Ocean closed, the crust of the West Siberian Plain consolidated, and it, together with the East Siberian and East European platforms, formed a single continent.
4. In the Devonian, an outbreak of kimberlite magmatism.
5. A powerful outbreak of trap magmatism occurred at the Permian–Triassic boundary.
6. In the Mesozoic, some parts of the platform were covered by epicontinental seas.
7. At the boundary of the Cretaceous and Paleogene, rifting and a new outbreak of magmatism, including carbonatite and kimberlite, took place on the platform.

A typical platform cover begins to form from the Riphean time and 7 complexes are distinguished in its composition. The Riphean complex is represented by carbonate-terrigenous, red-variegated rocks 4000-5000 m thick, filling aulacogenes and gentle depressions. The Vendian-Cambrian complex is composed of shallow-water terrigenous and terrigenous-carbonate deposits, and in the Angara-Lena trough - and saline (lower - middle Cambrian) strata, 3000 m. The Ordovician-Silurian complex is represented by variegated terrigenous rocks, as well as limestones and dolomites, 1000- 1500 m. The Devonian-Lower Carboniferous complex is limited; in the south, the Devonian is represented by continental red-colored strata with traps, in the north - by variegated carbonate-terrigenous deposits; in the Vilyui syneclise - a thick trap stratum and salt-bearing deposits, 5000-6000 m. lower - tuff and upper - lava parts (undifferentiated tholeiitic basalts); all deposits are intruded by dikes, stocks and sills of basalts; in the Devonian, Triassic and Cretaceous, kimberlite explosion pipes are formed in the northeast of the platform. The Upper Triassic - Cretaceous complex is composed of continental and less often marine sandy-clayey coal-bearing deposits, 4500 m, distributed only on the outskirts of the platform. The Cenozoic complex is developed locally and is represented by continental deposits, weathering crusts, and glacial formations. The Paleogene Popigai astrobleme is known on the Anabar massif.

Minerals

The East Siberian platform is rich in various minerals.

Large deposits iron ores are located on the Aldan shield, in the Angara-Ilim iron ore basin. Copper-nickel sulfide deposits are associated with traps in the Norilsk ore region, and cuprous sandstones are developed in the Udokan series on the Aldan Shield. Diamonds are confined to kimberlite pipes.

There are several large coal basins: large deposits of coal are known on the Siberian platform (the Lena coal basin, the Tunguska coal basin, the Irkutsk coal basin, the Kansk-Achinsk coal basin, the South Yakutsk coal basin). Deposits of rock and potash salt were discovered,

Siberian platform, or. as it is also called, the East Siberian platform, in order to distinguish it from the West Siberian, is one of the main objects of study of Russian geology. On its territory there are significant deposits of minerals, in addition, the study of its formation and current state is interesting from a purely scientific point of view. The depths and landforms of the Siberian Platform have been exciting the minds of more than one generation of scientists. Let's take a look at the main issues related to this continental area of ​​the earth's crust.

Geographic location

First of all, let's find out where the foundation of the Siberian platform is geographically located. Its main massif is located in the eastern part of Russian Siberia in the territories of the Siberian and Far Eastern federal districts. In the south, the platform reaches the territory of Mongolia.

From the west, its natural boundary is the channel of the Yenisei River, in the north - the Byrranga Mountains in Taimyr, in the east - the Lena River, in the south - the Yablonovy, Stanovoy, Dzhugdur ridges, as well as the Baikal fault system.

In the geological section, the Siberian Platform is a component of the Eurasian lithospheric plate and is located in its northeastern part. In the west, the West Siberian Platform adjoins it, in the south - the Ural-Mongolian belt, in the east - the Western Pacific belt, and in the north the waters of the Arctic Ocean splash, which are hidden under ice for most of the year.

History of education

Now let's find out how the corresponding landform of the Siberian Platform was formed over millions of years of geological processes.

This continental section of the earth's crust belongs to the type of ancient platforms, or cratons. Unlike other formations, they were formed back in the Precambrian period, which implies a minimum age of such formations at 541 million years. It was they that served as the basis for the formation of continents, becoming their core.

The Siberian platform belongs to the Laurasian type. This means that in the Mesozoic era it was part of the Laurasia continent. But much earlier than this period, the ancient Siberian platform began to form. The shape of the relief began to be outlined as early as the Archean era, that is, no later than 2.5 billion years ago. True, then it faintly resembled the modern one. The formation of the basement was completed at the beginning of the Proterozoic era, at the end of which the platform was covered with a shallow sea, which significantly affected the formation of the sedimentary cover. In the Late Ordovician, the platform was occupied by the Angarida continent. Later, it merged with other continents of the Earth into a single continent - Pangea. In the Mesozoic, as mentioned above, the Siberian platform, together with the West Siberian plate and the East European platform, after the separation of Pangea, formed the Laurasia continent. After its collapse, the Siberian platform became part of Eurasia.

This is how the Siberian platform was formed.

Structure

The structure of the Siberian platform is similar to the structure of all other ancient platforms. At its base is a foundation formed back in the Archean and at the beginning of the Proterozoic era. From above, the basement is covered by a sedimentary cover of rocks formed in later epochs, mainly as a product of magmatic activity. This is due to the fact that in ancient times it was a region with high volcanic activity, and the magma that emerged from the bowels of the earth formed a cover of traps. But in two places, the foundation of the platform still comes to the surface. The exit of Precambrian rocks to the surface is commonly called shields.

The shields consist of three rock complexes: greenstone, granular belts, and a complex of para- and orthogneisses.

Shields of the Siberian Platform

There are two shields on the territory of the Siberian platform - Anabar and Aldan.

Aldan is located in the southeastern part of the platform. In geography, this place is called the Aldan Highlands.

The Anabar Shield is much smaller in size and is localized in the northern part of the platform on the territory of the Central Siberian Plateau, in a place known as the Anabar Plateau. Its maximum height above sea level is 905 meters.

Central Siberian Plateau

Now let's see what the modern relief of the Siberian Platform looks like.

The main part of the territory is occupied by the alternation of low ridges and plateaus. The highest point of the plateau is Mount Stone. It is located in the Putorana middle mountains and has a height of 1701 meters above sea level. But the average height of the Central Siberian Plateau is only 500-800 meters. In addition, on this plateau, the Anabar Plateau, which we mentioned a little higher, should be distinguished. It is a protrusion of the Anabar Shield to the surface. The highest point of this plateau is 905 meters above sea level.

In the west, the plateau frames which simultaneously serves as a border for both it and the Siberian platform as a whole. Its average height is 900 meters above sea level, but it reaches its maximum on Mount Enashimsky Polkan and is 1104 m. Beyond the Yenisei Ridge lies the West Siberian Platform.

In the south and southeast, the Angara Ridge is the boundary of the Central Siberian Plateau. The average height is from 700 to 1000 meters above sea level, the maximum is 1022 m.

In the east and northeast, the Central Siberian Plateau, and hence the corresponding landform of the Siberian Platform, smoothly passes into the Central Yakut Plain. In another way, it is also called the Central Yakut, or Leno-Vilyui lowland. In most of its territory, the maximum height above sea level does not exceed 100-200 m, but on the outskirts it can reach 400 meters.

The relief form of the Siberian Platform on the internal watersheds is rather smooth. Therefore, the height of these watersheds does not exceed 400-600 meters. In particular, this statement refers to the boundaries of the Lower Vilyui and Tunguska basins.

Other relief elements of the Siberian Platform

In the southeast of the Central Siberian Plateau, unlike the objects listed above, it is not part of the plateau, but, nevertheless, is part of the Siberian Platform, representing an exit to the surface of its crystalline shield. It is on the territory of the Aldan Highlands that the highest point of the Siberian Platform is located, reaching a height above sea level of 2306 meters. But most of the highlands have a height not exceeding a thousand meters.

The relief form of the Siberian Platform in the extreme southeast has a mountainous character. Here, on the territory of the Khabarovsk Territory, the mountains of Dzhugdzhugur are located. Although the average height of this complex is higher than that of the Aldan Highlands, the highest peak, Topko, is inferior in size to the highest point of the highlands. Mount Topko is only 1906 meters above sea level. The length of the Dzhugdzhugur Mountains from northeast to southwest along the coast of the Sea of ​​Okhotsk is 700 kilometers.

So, we have learned in general terms what the shape of the relief of the Siberian Platform is.

Hydrography

Now let's focus on the main water bodies Siberian platform. As a rule, their initial location directly depended on the relief, and only then, after their appearance, rivers and lakes, which in the region are quite in large numbers, themselves begin to influence the formation of the terrain.

The largest water artery - the Yenisei - is the natural western boundary of the Siberian platform. This is one of the largest rivers in the world, the length of which is 3487 meters.

To a large extent, the border of the Siberian platform, only in the east, is another large river - the Lena. Although in part it carries its waters directly through the territory of the platform. Its length is 4400 km.

In the south, the Siberian platform in a small area is in contact with the deepest lake in the world - Baikal.

Among other major water arteries flowing along the Siberian platform, the Angara, Nizhny Vilyui and Tunguska rivers should be distinguished.

Minerals of the southern part of the Siberian platform

Now we should study the minerals of the Siberian platform. It should be noted that mother nature endowed the region with them in considerable quantities. What do the bowels of the East Siberian platform store?

The Aldan shield is a real repository of iron ores. In addition, copper, coal, mica and even gold are also mined in the Aldan Highlands.

But the most more stocks gold and diamonds are located on the territory of Yakutia, which is a real treasure trove of Russia. In the same republic, "combustible stone" is mined on the territory of the Lena coal basin.

In addition, coal mining takes place in the bowels of the Tunguska and Irkutsk basins, which are located in the territories of Yakutia, the Krasnoyarsk Territory and Irkutsk region.

Minerals of the north of the Siberian platform

Mineral resources of the Siberian platform in its northern part are mainly concentrated on the territory of the Anabar shield. There are deposits of apatites, anorthosites, titanomagnetites. Copper and nickel are mined near Norilsk.

But in oil and gas, in comparison with the regions, the territory of the East Siberian Platform is poor. Although there are also oil fields in the south and north, but in much smaller volumes.

Soils

Soils are the topmost layer covering the area of ​​the Siberian Platform. Consider what species they are represented in the region under study.

Considering that most of the Siberian Platform is covered by taiga, the soils formed here correspond to this natural zone. In the north they are permafrost-taiga, in the south - sod-forest. In the south, large areas are sometimes occupied by gray forest and even chernozems. Only the last type of soil from all listed is characterized by high fertility.

General characteristics of the Siberian platform

As you can see, the Siberian platform is one of the oldest geological formations on Earth. The relief in most of the territory is represented by plateaus, and only along the borders is the platform framed by relatively low mountains or hills.

The region is very rich in various minerals. Among them, iron ores, coal, apatites, gold and diamonds should be distinguished. There is oil, although this is not the main indicator of the wealth of the region. But the soils on the platform are not very fertile.

Siberian platform

The Siberian (Central Siberian) platform covers vast territory interfluve of Lena and Yenisei. Border her for the most part determined by deep faults. In the east, it stands out most confidently and practically coincides with the Lena valley, further south it almost reaches the coast of the Sea of ​​Okhotsk (Uda Bay) and sharply turns west-southwest to Chita. From here the border goes to the southern tip of the lake. Baikal, further west and northwest to the Yenisei, along the valley of which it rises up to the mouth of the river and again sharply turns east to the Khatanga Bay and the mouth of the Lena.

Speaking of Siberia, one involuntarily recalls the words of M.V. Lomonosov that "...wealth Russian Siberia will grow. "Even then, the brilliant scientist understood how rich this region was. Nevertheless, for many centuries Siberia was a remote taiga region, where the only trade was hunting for fur-bearing animals. In 1670, the Amsterdam bookseller Etienne Roger, who visited Siberia, wrote : "Siberia is a vast unexplored space, stretching to Chinese wall. Travelers to Siberia spend six years on this journey, being forced to stop in some places in winter and in others in summer. Furs, which you will not find in any other place, are the main subject of trade of the local inhabitants. Instead of bread, which is not here, they eat dried fish. For six to seven weeks, divided into groups, they go hunting on a sleigh, dressed in three or four layers of skins.

The industrial development of Siberia began only in the 19th century. But only after the Great October socialist revolution and especially in our day it has become carried out on a large scale. Recently, the French publicist P. Rondier, who visited this "bear corner", noted: "Nothing stands still here, everything moves, boils, rushes forward rapidly ... who knows nothing about it, does not know the future of our planet!

Despite the desire of geologists to unravel the secrets of the structure of the subsoil of the Siberian Platform as fully as possible and to explore the riches hidden there, the study of this territory is still very small. As of January 1, 1978, more than 2.2 million meters had been drilled here deep wells. However, the drilling density, i.e. the ratio of the total volume of available wells to the area of ​​the region, averages only 0.64 m/km 2, which is almost 17 times lower medium density deep drilling Soviet Union. Moreover, the volume of drilling is concentrated in central regions platforms, wells are located mainly along the river arteries. In most of the territory, only single wells have been drilled, and the drilling density varies between 0.001-0.08 m/km 2 . There are no wells at all in the central and northern regions of the Tunguska lowland.

AT more Geophysical surveys have been carried out within the Siberian platform. The area is covered by magnetic and gravimetric surveys. In a number of places, electrical prospecting and seismic surveys. Areal seismic exploration, which makes it possible to probe the structure of the subsoil in sufficient detail, was carried out on less than one fifth of the territory.

Summing up the consideration of the study of the subsoil of the Siberian Platform, it can be noted that more than half of its area is not covered even by regional geological and geophysical works. Nevertheless, the researchers of this hard-to-reach region have already lifted the veil over some of its geological secrets and are determined to continue the assault on the bowels.

Foundation mystery

So far, many regions of Siberia are fraught with many mysteries. One of them is the foundation of the platform. It emerges on the day surface in the north (Anabar ledge) and in the south (Aldan shield), and is also exposed along the periphery in the regions of Transbaikalia and along the Yenisei. The basement in the region of the Aldan Shield, where it is composed of Archean and Lower Proterozoic crystalline rocks, has been best studied. Three complexes are distinguished in the Archean group (from bottom to top): Iengry, Timpton and Dzheltulinsky, formed mainly by gneisses with lenses of ferruginous ores and marbles. This sequence is overlain by the Lower Proterozoic Olekminsky complex, consisting of crystalline schists and gneisses. The metamorphic rocks of the basement are intruded by powerful intrusions of granites, dunites and gabbro. In other places, the foundation of the Siberian platform has a similar composition.

Along the southern and western peripheries of the platform (Transbaikalia, the middle and lower reaches of the Yenisei), the basement also includes younger Proterozoic rocks represented by crystalline schists, quartzites, and conglomerates with interlayers of effusive igneous rocks. There are also granite intrusions (the Barguzin complex).

The basement of the Siberian Platform, as well as the basement of the East European Platform, consists of several large polygonal blocks with the age of consolidation from Archean to Late Proterozoic. This feature of the tectonic structure of the basement was noted even by the first researchers of the platform N.S. Shatsky and A.D. Arkhangelsky: “According to our ideas, the foundation of the Siberian Plate consists of elements of different ages, namely, from two ancient granite-gneiss blocks - the North Siberian (Anabar. - V. G.) and Aldan and from much younger folded structures of the Precambrian era, which encircle the Archean massifs.

Taking into account modern data, the regional structure of the basement of the Siberian Platform is determined by five main geoblocks: Anabar, Aldan, Vilyui, Tunguska and Baikal.

The Anabar geoblock extends from the Lena delta south to northern tip lake Baikal. It is composed of highly metamorphosed Archean complexes. The magnetic and gravimetric fields of the geoblock are characterized by linear anomalies of northwest strike.

The Aldan geoblock is located in the southeast of the Siberian Platform. It is formed by deeply metamorphosed, mostly Archean formations, crumpled into linear folds of northwest strike. The magnetic and gravimetric fields of the geoblock are variable, mainly with a northwest orientation of the anomalies.

Between the Anabar and Aldan Archean geoblocks, the Vilyui geoblock extends, presumably of the Early Proterozoic age of consolidation. Within its limits, the orientation of the anomalies of the magnetic and gravimetric fields changes sharply from northwestern to sublatitudinal.

The western part of the Siberian platform corresponds to the Tunguska geoblock. The structure of its foundation is the most debatable. The magnetic and gravimetric fields are obscured by the influence of the traps, which distorts the picture of the internal structure of the foundation. Presumably, the age of stabilization of the Tunguska geoblock is considered Early Proterozoic, although some scientists (P.N. Kropotkin, B.M. Valyaev, R.A. Gafarov and others) tend to consider it Archean.

The youngest (Late Proterozoic) Baikal geoblock of the basement of the Siberian Platform extends in a relatively narrow strip in the south, southwest, and west of the platform. It includes the Baikal folded zone, the Eastern Sayan, the Yenisei Ridge and the Turukhansk-Norilsk Ridge. Here, the deposits of the Upper Proterozoic are strongly dislocated, intruded by granite intrusions.

What is the mystery of the foundation of the Siberian platform? Not in the fact that it is still very little studied, but in the fact that even the initial steps in the knowledge of it brought a lot of unexpected, if not sensational. So, in the south of the Aldan shield, several years ago, geologists discovered relics of the most ancient earth's crust, formed 4-4.5 billion years ago, when the planet was at the lunar stage of its development. To make it clearer to the reader what it is, we will make a short digression into the past of the Earth.

At the very early stage of its formation, our planet experienced a development that was quite unusual in modern times. It had no atmosphere, no hydrosphere, no earth's crust. There was a core and a mantle. Under the influence internal heat released by the decay of radioactive elements, the upper part of the mantle began to melt. At the same time, differentiation of matter took place, light components were sublimated upward, forming "seas" of molten basalt lava. During the melting of the primary rocks of the mantle, vapors of various gases and water were released from them, which eventually led to the formation of the hydrosphere and atmosphere. Truth chemical composition theirs was quite different than it is now. The then landscape of our planet was probably very similar to the panorama of the Moon or Mars. Scientists have long assumed such a possibility of events on Earth, but there were no facts. Back in 1922, Academician A.P. Pavlov expressed an original hypothesis that the Earth and the Moon once developed in the same way. But the Moon, having exhausted its internal energy, stopped its development, retaining its face, formed several billion years ago, to this day. The earth has moved on and has changed beyond recognition since then. What facts did A.P. Pavlov have? Virtually none, mostly the intuition of a scientist and the imagination of a geologist. "Imagination is more important than knowledge ..." - these words belong to the brilliant scientist A. Einstein, and the great G. Lorca wrote: "For me, imagination is a synonym for the ability to discover ...". Our example is a clear proof of this.

It seemed that man would never penetrate the secrets of the ancient existence of our planet. And here is an unexpected find: rocks of the Sutam series in the south of the Aldan shield. Why are they unusual? First, its composition. These are very specific shales, eclogite-like rocks, gabbro-norites and gabbro-anorthosites. The formation of these rocks, as established by the researchers, occurred at very high pressures of 1000-1200 MPa and temperatures of 700-800 °C. The chemical and mineral composition indicate their kinship with lunar basalts. Secondly, the age of the series is 4.5-4.58 billion years. Geologists have not yet known such ancient rocks. Thirdly, a peculiar tectonics: the dominance of negative rounded structures such as bowls, consisting of a chaotic accumulation of ring, oval, looped negative forms separated by narrow ridge-like uplifts (Fig. 8). E.V. Pavlovsky, one of the leading scientists of our country who studied these unusual rocks, concludes: “The oldest age of the rocks of the Sutam series, the proximity of their composition to lunar basalts, the predominance of negative unoriented structures give grounds for attributing the series to those formations that arose in course of the lunar stage of the earth's life. Later, by analogy with the Siberian platform, they began to distinguish the remains of the lunar crust on Kola Peninsula, in Africa (Southern Rhodesia). Analyzing space images, geologists have found buried remains of the lunar crust and in closed areas of platforms along mysterious ring structures.

Nuclear nuclei were also found in the body of the foundation of the Siberian platform, reflecting the next stage of the development of the Earth after the lunar one * . The presence of such cores can be noted within the same Aldan shield. The absolute age of the domes is 3.3 billion years. Thus, one of the most ancient pages of the chronicle of our planet is being clarified, and the study of the foundation of the Siberian Platform played a significant role in this.

* (Not all geologists agree with the idea of ​​the existence of the lunar and nuclear stages of the Earth's development. Some (Ch. B. Borukaev and others) are inclined to explain the presence of bowl-shaped structures of the Sutam complex and nuclear nuclei by other reasons.)

The internal structure of the foundation of the platform under consideration is the same as that of the East European one. Here there are mainly anticlinoria and synclinoria, expressed in the terrain by relatively low mountain ranges.

Sedimentary cover structure

The sedimentary cover is developed over most of the Siberian Platform. Characteristically, the Upper Proterozoic complexes lie directly on the crystalline basement. The thickness of the cover changes sharply from 0 to 10.0 km. It consists of deposits of the Upper Proterozoic (Riphean), Paleozoic, Mesozoic and Cenozoic.

The Riphean deposits, represented by red sandstones, conglomerates, interlayers of bituminous limestones and combustible shales, everywhere begin a sedimentary cover, with the exception of the young Baikal block, where they are part of the basement. It is characteristic that the Riphean formations, as a rule, are present in aulacogenes and do not go beyond these graben-like basement troughs. The Vendian deposits (Yudoma Formation) are developed in space more widely, they are composed of clastic rocks and dolomites.

Paleozoic deposits cover the foundation with a continuous cloak. According to the lithological feature, they are divided into two strata: the lower one is predominantly carbonate and the upper one is predominantly clastic. The lower sequence includes rocks of the Cambrian, Ordovician, and Silurian systems. These are limestones, marls, dolomites up to 4-4.5 km thick. A distinctive feature of the Lower Paleozoic deposits is the presence in their composition of a powerful Cambrian salt-bearing stratum, which can be traced from the Yenisei Ridge in the west to the Lena River in the east and from Lake. Baikal in the south to Norilsk in the north. Here is how academician A. L. Yanshin characterizes these unique rocks: “The thickness of salt-bearing deposits in the basin reaches 3 km. Its area approaches 2 million km, and the mass of salt accumulated in it, according to modern estimates, is at least 5 ,85*10 5 km 3".

The upper sequence of the Paleozoic includes deposits of the Devonian, Carboniferous and Permian. Devonian formations are limited in space (mainly in the northwest), they are composed of clastic rocks of continental origin with interlayers of lagoonal sediments and volcanic tuffs.

Deposits of the Carboniferous and Permian systems of the Paleozoic group, together with sediments of the Triassic system of the Mesozoic, form a very peculiar stratum, encountered in our country only on the Siberian platform. It is distinguished under the name of the Tunguska series, since it is present mainly in the west of the platform within the Tunguska syneclise. The originality of the series lies in the fact that it is all "stuffed" with layers of basalts. A "layer cake" was formed, consisting of alternating layers of sandstones, mudstones, coal, basalts, volcanic tuffs, tuff conglomerates. The upper part of the series is overlain by lava flows of basaltic, diabase, and porphyritic composition. Layers of lavas created stepped forms in the relief, resembling a ladder (trapp), in connection with which the whole complex of deposits was called the trap formation. The formation of traps occurred at the end of the Paleozoic - the beginning of the Mesozoic, when basalt lava penetrated to the surface along the "revived" deep faults from the bowels of the platform. At the same time, diamondiferous explosion pipes (diatremes) were also formed. This unusual activation of the faults of Siberia is associated with the global activity of the internal forces of the Earth, which initiated the split and "spreading" of the previously unified supercontinents Gondwana (southern hemisphere) and Laurasia (northern hemisphere).

The total thickness of the deposits of the Tunguska series is several kilometers, and the area covered by it is more than 500,000 thousand km 2. It must be said that the traps make it very difficult to study the deep structure of the platform. Indeed, most often research is carried out using seismic exploration methods, and at the same time sent deep into the earth's crust elastic waves are reflected from the basalt layers and "in disarray" return back before reaching the desired depth. Extra information"confuses the maps" and makes it impossible to find out the tectonic structure of the deeper bowels.

The Mesozoic deposits of the Siberian Platform (except for the Triassic) are developed to a very limited extent. Jurassic sediments are known in the east (Vilyui syneclise) and in small spots in the west (Irkutsk, Kansk, Rybinsk depressions), Cretaceous - only in the east (Vilyui syneclise). They are represented by sandstones, clays of coastal-marine and continental origin. Interlayers of hard coal, often of industrial importance, are noted in large quantities. The total thickness of Mesozoic deposits sometimes exceeds 3-4 km.

Cenozoic rocks are found only in the intermontane graben-like depressions of Transbaikalia: these are weathering crusts (Paleogene) and red-colored conglomerates (Neogene), the thickness of the latter sometimes reaches 2 km. Quaternary sediments are represented by alluvial, glacial, lacustrine-marsh formations, sometimes by peat interbeds.

AT tectonic structure The Siberian platform is attended by a variety of geostructural elements: it is a shield and a plate; massifs, anteclises and syneclises; arches, zones of uplifts, swells, depressions, deflections, etc. Large convex (positive) structural elements are concentrated mainly on the periphery of the platform, and sagging (negative) structures in its central regions (Fig. 9).

The most significant uplift of the platform is the Aldan shield, which we have already mentioned. Let us add that, in addition to anticlinoria and synclinoria, its structure is also complicated by the Ulkan and Bilyakchan aulacogenes and superimposed Mesozoic depressions, which form the South Yakutian band of sublatitudinal depressions (Chulman trough, Gonomskaya and Tokyo depressions). The depressions are of a graben-like nature and probably owe their origin to the activity of a deep fault that became active in the Mesozoic era. The shield also includes the Berezovskaya depression, located in its northwestern part and filled with sediments of the Riphean, Lower Paleozoic and Jurassic.

The Baikal folded area continues the mountainous framing of the Siberian Platform to the southwest of the Aldan shield. It is located between the lake. Baikal and the Aldan shield, including the Vitim and Patom highlands. The outer and inner zones, consisting of anticlinoria and synclinoria, are clearly distinguished in the composition of the region. The zones are separated by the Baikal anticlinorium, which stretches along the southeastern coast of the lake of the same name.

AT Cenozoic era The Baikal folded area experienced an activation of block movements along deep faults, which led to the formation of graben-like depressions. One of them, the largest in size, is occupied by the waters of the lake. Baikal. The resulting depressions are filled with a thick layer of Cenozoic sediments. Only the share of Neogene-anthropogenic deposits accounts for up to 1.2 km. Tectonic nature of the lake. Baikal has previously been proven exclusively by outward signs; steep coasts, outcrops of solidified basaltic lavas, characteristic geophysical anomalies. In 1977 Baikal researchers made an attempt to directly study the underwater geology of the lake. It turned out that the slopes of the depression have a stepped structure. They are formed by a system of parallel faults dividing the sides of the lake into separate tectonic plates. Some faults are expressed in the bottom topography as narrow underwater canyons. The slopes of the lake are composed of basalt rocks that have risen to the surface along cracks in the earth's crust.

Active shifts along the faults, which in due time led to the formation of a graben of the lake. Baikal, continue in our time. This area belongs to seismically hazardous areas. There have even been cases of catastrophic earthquakes. One of them happened in 1861 with the epicenter in the center of the lake. In one night, the Saganskaya steppe with an area of ​​​​230 km 2, located near the Selenga delta, sank (G. E. Ryabukhin, 1940).

To the southwest, south, and northwest of the Baikal region, the East Sayan folded zone extends, which is also part of the Baikal geoblock of the basement of the Siberian Platform. The pre-Riphean and Riphean complexes of this zone are folded into northwest-trending folds, which are grouped in the Proterosayan and Khamar-Daban anticlinoria. Within the East Sayan zone there is a graben-like Rybinsk depression, formed in the Mesozoic era and superimposed on the ancient foundation.

The Yenisei shield (ridge) limits the internal sag areas of the platform from the west. This is an area of ​​Early Baikal folding, where basement formations are widely developed on the surface, crumpled into box-like folds, anticlinoria and synclinoria.

The Turukhansk-Norilsk ridge continues to the north the strip of the Baikal folded structures of the platform. The ridge is elongated in the submeridional direction and consists of two horst-shaped basement protrusions, the slopes of which are limited by deep faults.

These geostructural elements (Aldan shield, Baikal folded region, Eastern Sayan, Yenisei ridge and Turukhansk-Norilsk ridge) form the outer arched frame of the Siberian platform, enveloping its inner regions from the south and west. The rest of the platform is characterized by the subsidence of the basement of different ages and the wide development of the sedimentary cover. This internal submerged part of the platform stands out as the Central Siberian (Lena-Yenisei, according to N. S. Shatsky) plate. The relief of the foundation of the slab is extremely complex, which is explained by the manifestation of multi-amplitude and multi-directional tectonic movements, which determined the features of the formation of geostructural elements. The plate includes the Anabar massif, the Nepa-Botuobinskaya and Baikitskaya anteclises, the Tungusskaya, Sayano-Yenisei and Vilyui syneclises, the Angara-Lena trough, the Predverkhoyansky foredeep, and other smaller structural elements.

The Anabar massif is one of the largest positive geostructural elements of the plate. Its boundaries are deep faults. The massif includes the Anabar ledge (shield) and the Olenek ledge (arch), delimited by the Sukhansky trough, as well as the Munsky arch and the Morkokinsky mega-swell, separated by the Markhinsky trough. The structures of the Anabar massif are poorly studied. They are developed within the distribution of the Cambrian-Silurian deposits and form gentle domes, megaswells or swells separated by troughs. The dip angles of the seams do not exceed a few degrees. Some swells are confined to flexural folds of the cover and are associated with deep basement faults.

The Nepa-Botuobinsk anteclise is located between the Tunguska and Vilyui syneclises and the Angara-Lena trough. The study of the geological structure of the anteclise is practically just beginning. In its composition, a number of arched uplifts are distinguished (Nepsky, Syuldyukarsky, Mirnensky, Peleduysky, Chonsky arches), separated by depressions and troughs. The depth of the foundation is 2-2.5 km.

Geophysical studies of recent years have made it possible to identify another large uplift located in the west of the platform near the Yenisei Ridge - the Baikit anteclise. Its dimensions are 1000 km X 400 km. The foundation is covered with a three-kilometer layer of sediments. The structure of the anteclise has not yet been studied, and the structure itself, despite its impressive size, became known to geologists only relatively recently.

The Tunguska syneclise, the largest structure of the Siberian Platform (1500 km X 700 km), is a huge depression of submeridional strike, opened to the north. In the west it is bounded by the Turukhansk-Norilsk ridge and the Baikit anteclise, in the south by the Nepa-Botuobinsk anteclise, in the east by the Anabar massif. The boundaries are tectonic. The Tunguska syneclise was formed by a thick (up to 10 km) sequence of sedimentary volcanic rocks. From the surface, it is overlain by continental rocks of the Tunguska series. The beds are inclined from the sides of the syneclise to its center at an angle of up to 3°.

As part of the syneclise, several depressions are distinguished, of which the largest are the Kurey and East Tunguska. Depressions and swells are complicated by local uplifts with an angle of dip of wings usually 3-5° and with amplitudes up to 150-200 m. Folds, as a rule, have a simple structure (flat vaults and gentle wings). In general, the syneclise is characterized by a number of structural features inherent only to it: a flat bottom, surrounded by relatively steep sides, which are complicated by flexures and faults; significant role of magmatic products in the structure of the section. This gave rise to a number of scientists, in particular M. V. Muratov, to distinguish the Tunguska syneclise as a special type of platform structures, which he called amphiclises.

To the north of the Tunguska syneclise, there is the Yenisei-Khatanga trough, which is elongated in a sublatitudinal direction. The structure of the deflection has not been studied. It has been established that it is filled with a thick layer of Paleozoic and Mesozoic sediments. Earth's crust within its limits it is thinner than it usually happens on the platforms: its thickness is 27-30 km.

The Vilyui syneclise stands out in the southeastern part of the Siberian Platform. The total thickness of the cover here reaches 8.0 km. central part The syneclise is occupied by the Urinsky aulacogen of northeastern strike, which is probably filled with Riphean rocks. The syneclise developed most actively in the Mesozoic time (starting from the Jurassic). It contains a number of depressions (Lindenskaya, Lunkhinskaya, Ygyattinskaya, Kempendyayskaya) and swell-like uplifts separating them (Suntarskoye, Khapchagayskoye, Namaninskoye). In some depressions (Kempendyai), strata of rock salt are known, apparently of Cambrian age. Salt here forms domes with wing angles of up to 40-60°, strongly broken by faults. In the relief, salt domes are expressed as small hills up to 120 m high.

The Sayano-Yenisei (Biryusa) syneclise is located between the Yenisei Ridge, the Nepa-Botuobinskaya and Baikitskaya anteclises. Its boundaries are deep faults. It is filled mainly with Paleozoic deposits. The thickness of the cover within its limits reaches 8.0 km. The syneclise includes the Dolgomostovskaya, Murskaya, Kanskaya, and Tushamskaya depressions, separated by the Chunsky, Bratsky, and Pushkinsky (Pushkinsko-Zakharovsky) swells. The basement is most deeply submerged in the Kansk graben-like depression, which is filled with coal-bearing Jurassic deposits.

The Pre-Verkhoyansk foredeep of the Mesozoic age extends along the entire eastern periphery of the Siberian Platform for a distance of 1200 km and a width of up to 120 km. It separates the Precambrian Siberian Platform from the Verkhoyansk-Kolyma Mesozoic region.

Between the Central Siberian plate and the Baikal folded region is the Angara-Lena trough, which extends for 1500 km. The trough is filled with Riphean and Lower Paleozoic deposits; in the south, within the Irkutsk superimposed depression, Jurassic rocks appear. The Cambrian formations contain a salt-bearing stratum up to 1.5 km thick, which divides the sedimentary cover into subsalt (Riphean) and post-salt (Lower Paleozoic) complexes.

Gold, diamonds and their connection with faults

In the depths of the Siberian platform, deposits of oil and gas, iron, coal, copper, nickel, gold, platinum and a number of other useful and the right people fossils. Some underground storerooms have been developed for a long time, others have been discovered recently, and others are still being sought by geologists and geophysicists. Perhaps, greatest fame Siberia was brought by a noble yellow metal, which has been mined on an industrial scale in the taiga wilds of the region for more than 100 years.

Primary gold deposits are known here in the form of quartz-gold-bearing veins in the ancient granites of the Aldan shield, the Anabar massif, the Yenisei ridge, and Transbaikalia. Placer gold deposits are much more widespread in the floodplains of the Lena, Aldan, Yenisei, Bodaibo and other rivers. Their development is carried out by drag or career methods, and, despite severe frosts, all year round. In winter, a jet of hot steam melts the river ice, which prevents the washing of bottom sand, while the dredge itself continuously spews hot water during operation, which prevents the polynya from dragging on.

An interesting pattern emerges in the spatial distribution of primary deposits of gold; as a rule, they are associated with deep faults in the crust. This is most clearly observed in the well-exposed and, accordingly, more studied regions of Transbaikalia and the Aldan shield.

As you know, Transbaikalia is a relatively young platform geoblock. At the platform stage of development (i.e., the last 700-600 million years), it experienced predominantly ascending vertical movements along faults that form orthogonal and diagonal systems. The degree of manifestation of faults within its various structural zones is not the same. In the Lensky gold ore region, sublatitudinal ruptures are clearly manifested. Gold-bearing nodes (Kropotkinsky, Artemovsky, etc.) are confined to the places where these zones intersect with weakly pronounced northwest-trending faults. In the Mamsky district, gold occurrences gravitate towards a deep fault with a northeast orientation, which is clearly marked by a series of ultrabasic intrusions. In the Patom Highlands, northwest-trending faults dominate. In general, for the regions of Transbaikalia, it is this direction of faults that is of decisive importance. Faults of sublatitudinal and northeastern directions are less pronounced, and gold-bearing veins within them are found only at their intersections with faults of northwestern strike.

A significant role in the distribution of mineralization in Transbaikalia is played not only by the large deep faults themselves, but primarily by the shallow faults associated with them. Indicative in this respect is the structure of the Irokinda-Kindikan ore field (Fig. 10). The main ore-controlling structure here, according to many geologists, is the Kilyansky fault, referred to within the ore field as the Irokinda. Most of the productive veins are located in the faults of the northeast strike, the smaller part - in the faults of the northwest direction. Almost all veins are associated with cracks associated with the main fault, only individual ore bodies were found directly in the zone of the fault itself. All veins fall to the northwest or southwest at an angle of 30-45°. Faults are characterized by the predominance of reverse-shear or normal-shear displacements, which caused the opening of cracks. The shapes of the ore bodies are controlled by the bends of the faults and the places where they intersect. The confinement of gold mineralization to the intersection nodes of regional faults of similar directions is also noted for the Cis-Baikal and Eastern Sayan regions.

In the south of the Siberian Platform, within the Aldan shield, there is a large elongated horst that formed in the early Proterozoic time - the Stanovoy Range. Within its central part, gold mineralization is known, which was formed in the Mesozoic era. At this time, the constituent blocks of the Stanovoi Ridge "came to life" again, which experienced multidirectional movement in the vertical direction along the faults limiting them. In the Early Cretaceous, there was an intensification of volcanic activity, accompanied by gold mineralization, and in the Late Cretaceous, a new outbreak of volcanism and the formation of gold, mercury, antimony, and arsenic.

The largest fault of the Stanovoi Ridge, which controls ore formation, is the Apsakan zone of ancient origin of sublatitudinal orientation, which is intersected by faults of the northeast direction. Together, these systems form the Apsakan gold-bearing cluster here (Fig. 11). The localization of ore bodies is observed along the entire fault zone, however, the richest ores are found in places where it intersects with northeastern faults. Here, the fracturing of the rocks increases sharply, and the cracks, according to experts, served as the channels through which ore-bearing solutions moved.

The ore-controlling role of faults affects not only the formation of gold deposits. Studying the patterns of distribution of ore deposits in Transbaikalia, a number of scientists, in particular D. I. Gorgievsky, N. A. Fogelman and others, came to the conclusion that deposits of polymetallic ores and ores of non-ferrous metals (molybdenum, tungsten, lead, zinc, tin, arsenic, etc.) gravitate towards the intersection nodes of latitudinal and diagonal faults. Moreover, as noted by these researchers, ore-bearing faults are characterized by a duration of development.

In addition to Transbaikalia, deposits of non-ferrous metals have been discovered in the area of ​​the lower reaches of the Yenisei (copper, nickel, etc.). Here, sulfide mineralization has been established in an intrusive body of ultramafic composition. The intrusion is confined to a large deep fault that limits the Siberian platform from the west. There are also platinum deposits here. On the basis of this pantry, the Norilsk Mining and Metallurgical Combine was created. Copper deposits are also known in the Olekma-Vitim interfluve (for example, Udokan).

An interesting fact: despite the fact that the Siberian platform has been studied much less geologically than the East European one, it is openly incomparable here. large quantity deposits of noble and non-ferrous metals. Does this mean that the subsoil of Siberia is much richer than the subsoil of the European part of the country? Such a conclusion cannot be drawn. And that's why. In the areas of the Siberian Platform, the basement rocks come out to the surface much more often. Here the area of ​​their outcrops is 3 times larger than on the East European platform. But the vast majority of ores were formed in geosynclines, where the sublimation of deep matter into the upper horizons of the crust was especially active. That is why ore accumulations are located in geosynclinal formations that form the foundations of the platforms. Abroad, for example, the outcrops of the foundations of ancient platforms provide about two-thirds of the extraction of iron ore, three-quarters of gold and platinum, nine-tenths of nickel, cobalt and uranium, almost all of the extraction of thorium, beryllium, tantalum, niobium and zirconium, about a third of the extraction of manganese , more than a quarter of copper and chromium.

If gold and other precious and non-ferrous metals have long been the glory of Siberia, then diamond mining is a relatively new business here. The first diamond was found in Yakutia in channel sediments in 1948, and the first kimberlite pipe was discovered in 1954. Diamond-bearing kimberlite pipes are oval tubular bodies up to 500 m in diameter filled with brecciated rock (kimberlite). The tubes go almost vertically to the depth. Their formation is associated with a sudden breakthrough of ultrabasic magma from the depths along narrow cracks or channels. In this case, the so-called explosion tubes (diatremes) are formed. Under conditions of enormous pressure and high temperatures crystallization of carbon and the formation of diamonds. The best known explosion pipes are Mir, Aikhal, etc.

As we already know, unusually active magmatic processes engulfed the Siberian platform at the end of the Paleozoic - the beginning of the Mesozoic, when the Tunguska series of deposits was formed. At the same time, the formation of diamond-bearing explosion pipes associated with deep fault zones also occurred. Geologists began to use this connection as a search feature. For example, space research in Yakutia established submeridional faults. Some of them are associated with kimberlite fields. Within one of these fields, industrial diamond-bearing pipes are known, producing stones of rare beauty. Recently, on the eve of the 60th anniversary of October, in the Udachnaya pipe, not far from the village. Mirny, found a diamond of 120 carats (1 carat = 0.2 g). They called it "60th anniversary of the Great October Revolution".

Oil, gas and coal

Combustible raw materials are essential for the harmonious development of industry Eastern Siberia. By the beginning of 1978, 22 oil and gas fields had been discovered here, and encouraging signs of these minerals were obtained in 25 areas. However, the total identified reserves of "black gold" are still very small. According to experts, they make up only 2.7% for gas and 0.1% for oil of those predicted reserves that are scientifically substantiated by geologists. This means that major discoveries are yet to come. Therefore, in recent years, the front prospecting work for oil and gas has expanded significantly. So far, deposits are known within the Vilyui syneclise, the Angara-Lena trough, and the Nepa-Botuobinsk anteclise.

The first gas deposit within the Vilyui syneclise was discovered in 1956 in Cretaceous deposits. A group of deposits has already been discovered here - Srednevilyuiskoye, Nedzhelinskoye, Sobokhainskoye and others. Gas fields have also been established in the adjacent areas of the Predverkhoyansk foredeep. The deposits here are confined to terrigenous rocks of the Mesozoic and Upper Permian and are associated with anticlinal folds. The depth of their occurrence is 1-2.5 km, and in the central regions of the syneclise up to 3-3.5 km.

In the Angara-Lena trough, oil and gas deposits are contained in the Lower Cambrian and Vendian deposits. Productive horizons are established in the pre-salt terrigenous complex, in the inter-salt and post-salt terrigenous-carbonate complexes. The average depth of productive horizons is 2.5 km. The deposits are confined to local uplifts; lithologically limited deposits are also known. Markovskoye, Krivolukskoye, Ilimskoye, Yuzhno-Ustkutskoye deposits and others have now been identified in this area. The most studied is the Markovskoye deposit, located near the village of Markovo, Ust-Kutsky district, Irkutsk region. Here, in 1962, from a depth of 2164 m, an oil fountain was obtained from sandstones of the Lower Cambrian. The initial flow rate of the well reached 1000 m 3 /day. Markov oil is the first Cambrian oil in the Soviet Union.

Recently, industrial gas inflows have been received within the Nepa-Botuoba anteclise (Nepsky arch), which, undoubtedly, will be a new region of the Siberian platform that is most interesting in terms of oil and gas content. While open here gas fields cannot be considered significant. The largest of them, the Srednebotuobinskoye field, contains a gas deposit with dimensions of 55 km X 18 km and a height of about 20 m. Well flow rates reach 720 thousand m 3 /day. The deposit is confined to sandstones of the Vendian age. Another thing is striking: wherever wells are drilled within the Nepa-Botuoba anteclise, they, as a rule, uncover the Cambrian, Vendian and Riphean rocks saturated with droplet oil (data from A.V. Ovcharenko, V.E. Bakin, 1979). This means that the subsoil of the region is enriched with "black gold".

The Krasnoyarsk Territory (the region of the Tunguska syneclise) is characterized by certain potentialities. Scientists have long been in favor of prospecting for oil and gas here. And in 1977, the first fountains of gas and oil were obtained from the subsalt deposits of the Motskaya suite (Vendian). Productive wells were drilled east of the Yenisei Ridge and near the village. Vanavara on Podkamennaya Tunguska. Industrial deposits of oil and gas in the Lower Cambrian deposits have been identified in the Kuyumbinskaya area. Let's hope that these are only the first signs.

There are many unusual things in Siberia. There were no surprises for the gas workers either. In Yakutia, researchers first encountered the property of natural combustible gas to be in the earth's crust in a solid state. Now experts are deciding how to develop such deposits and evaluate their reserves. In the future, solid gas may become an important source of blue fuel.

Coal is of great importance for the development of industry in the central and eastern regions of Siberia. Its deposits are quite widespread in the bowels of the platform, and the total reserves make up 68% of the all-Union reserves of brown and hard coal. In most cases, productive layers occur in Jurassic and Lower Cretaceous rocks. The largest coal basin within the Siberian platform, the Lena coal basin, occupies the territory of the Vilyui syneclise and the Predverkhoyansk foredeep. total area it is 400,000 km 2, and coal reserves for 1955 were estimated at 2647 billion tons. Over the past 20 years, geologists have explored new coal deposits here, and now this is one of the richest basins in the world. Productive layers are confined to Cretaceous and Jurassic deposits, their thickness reaches 5-8 m.

The Tunguska coal basin is somewhat inferior to the Lena, its reserves in 1955 were estimated at 1744 billion tons. Productive horizons are associated with the Upper Paleozoic deposits of the Tunguska series. In places where productive layers are breached by traps dikes, coal is graphitized. The Kansk-Achinsk coal basin is located in the southwest of the Siberian platform. Layers of combustible stone are confined to the Jurassic sequence, which fills graben-like depressions (Irkutsk, Kansk, Rybinsk). The total reserves of coal, mainly brown, reach 1220 billion tons. Now, on the basis of this basin, the Kansko-Achinsk energy complex. Not far off is the time when they will grow up here thermal power plants and other energy-intensive industries.

Other riches of the Siberian bowels

We have not yet said anything about deposits of iron, bauxite, mineral salts, numerous types of non-metallic raw materials, which Siberia is so rich in.

Iron on the Siberian Platform has been discovered and is being explored in five iron ore basins: the Angara-Ilim, Sredneangarsky, Angara-Katsky, Angaro-Pitsky and Yuzhno-Aldansky. Ores of hydrothermal, sedimentary, and metamorphic origin are confined to Proterozoic and Lower Paleozoic deposits. The content of iron in ores is up to 45%, its total reserves are estimated at over 4 billion tons. In the western part of Transbaikalia, deposits of magnetite ores have been established in the Iron Range mountain range. Similar deposits of ferruginous quartzites are known in the Eastern Sayan, on the Yenisei Ridge.

Bauxite deposits are being developed within the Yenisei Ridge. The deposits here are confined to loose Paleogene deposits filling karst depressions in the carbonate rocks of the Cretaceous and Cambrian. Bauxite deposits have been established in the Buryat ASSR in the Lower Cambrian.

Mica deposits (mainly muscovite and phlogopite) have been identified along the northwestern margin of the Baikal folded region, the eastern slope of the Eastern Sain (deposits Bukachanskoye, Akukanskoye, Slyudyanskoye, Biryusinskoye, Yeniseiskoye, etc.)

Icelandic spar, which is used in the optical industry, is associated with Upper Paleozoic trap intrusions. Its deposits were discovered in the Krasnoyarsk Territory.

Early Cambrian rock salt, the reserves of which are practically inexhaustible, is being developed so far only in the Irkutsk region (Irkutsk salt-bearing basin), where several thick productive strata are located close to the surface.

Other non-metallic minerals of the Siberian Platform include graphite (Noginskoye deposit), magnesite (Talskoye and Kardakinskoye deposits on the Yenisei Ridge), phosphorite (Iliktinskoye deposit in Western Transbaikalia), corundum (Chaynytskoye deposit in the Stanovoy Ridge), kaolin and rock crystal (Irkutsk deposit in the Aldan basin), ornamental semi-precious stones, in particular lapis lazuli (Transbaikalia).

The Siberian subsoil is also rich in facing materials of amazing beauty, primarily marble. Its unique deposits were discovered in the southeast of the Novosibirsk region. Along with white, gray and cherry red marble, the rarest variety of bright green color was found here. On the territory of our country, this is the only deposit of green marble. In terms of its qualities, it is not inferior to the famous Italian, which is highly valued in the world market. The reserves of the deposit are more than 1.5 million m 3 . Siberian marble will find its first use in the decoration of Novosibirsk metro stations.

Finally, it is necessary to say about the mineral and thermal springs, which are still practically not used. Only in the lake area Scientists from the Institute of the Earth's Crust of the Siberian Branch of the USSR Academy of Sciences have discovered more than 300 outcrops of underground water with a high content of mineral salts. 23 sources have medicinal properties. Mineral waters of deep origin, they made their way to the surface of the Earth along the faults that outline the lake. Hot springs with water temperatures up to +60 °C were also found here. Similar thermal springs have been identified in the valleys of the Upper Angara, Chara, Olekma, Byssa, Bureya and their tributaries.

Underground storerooms along the BAM route

As you can see, the Siberian bowels contain considerable wealth, but many treasures are still waiting in the wings. The exploration of these natural storerooms is hindered primarily by difficult climatic conditions. But the development of the national economy of our country urgently requires the active involvement of Siberian deposits in the industrial production, and in the shortest possible time. One of the decisive steps taken in the development of the wealth of Siberia is the construction of the Baikal-Amur Mainline (Fig. 12). The creation of this route will make it possible to sharply increase production in all adjacent areas, and the area of ​​\u200b\u200bthese lands is considerable. According to experts, it is 3.5 times larger than the territory of France. The active development of the Kodaro-Udokan copper ore province, the Kansk-Achinsk coal basin, underground oil and gas deposits of Yakutia will begin, thermal and mineral waters of Lake Baikal will find application, etc.

The construction of BAM is a school of courage, civic maturity for thousands of young enthusiasts who have to overcome great difficulties - bitter cold in winter and heat in summer, gnat, disorder of life. Quite unexpectedly, it turned out that the gentle mountain ranges along which the highway will run are avalanche-prone. Only in the area of Naminga has up to 250 avalanches per year. Before the track arrives here, it is necessary to find effective ways to combat the "snow death".

So far, there is only one way - the preventive release of avalanches with mortar rounds.

According to experts, the cost of BAM is quite an impressive figure. Naturally, the question arises: are the bowels of this region rich enough, which the highway is designed to awaken? How many pantries have nature prepared along the route? The BAM passes through one of the most complex geologically constructed parts of our country. Research in these areas has been going on for a long time. A geological survey of the territory gravitating towards the highway has already been carried out. The work was carried out by a large team of geologists under the guidance of A.I. Krasny, Corresponding Member of the USSR Academy of Sciences. Deposits of tungsten, molybdenum, titanium, tin, fluorite, manganese, polymetals, iron, lead, zinc, copper, apatite, phosphates, precious and ornamental stones, building materials. The range of minerals, as we see, is quite large.

The greatest glory of the Baikal-Amur Mainline was brought, perhaps, by Udokan copper. In its middle part, the route passes through the picturesque Chara Valley, surrounded by the Udokan and Kodar mountain ranges, some peaks of which rise more than 3 km. The ore of the Udokan Range is very diverse in composition and contains many valuable impurities. Geologists have not yet fully completed the exploration of the Udokan subsoil, but the value of this deposit has already been determined. The adits bite into the ridge for more than 1.5 km - and copper is everywhere. Even the famous mistress of the copper mountain would look like a poor relative compared to Udokan. In the valley itself, deposits of iron, coking coal, and building materials have been discovered. Near Char, a deposit of a previously unknown pink-violet mineral was found, which was called charoite.

Great prospects are associated by specialists with the development of unique igneous rocks of alkaline composition of the Synnyr massif. Alumina, a raw material for aluminum production, valuable potash fertilizers, potash and other useful substances, can be obtained from these synnyrites.

In the north of Buryatia, 18 km from the steel line, the Molodezhnoye asbestos deposit was discovered. The mineral lies literally on the surface, so it can be mined in the cheapest quarry way. This pantry is rare: asbestos has a very high content of textile fibers, the length of which reaches 12 mm.

The enumeration of underground storerooms along the Baikal-Amur Mainline can be continued, but what has been said is enough to conclude that capital investments in the construction of the route will pay off with interest. Those who will develop the subsoil here are faced with the task of the most rational, comprehensive use of these resources. Geologists now not only look for and explore new deposits, but also compile a catalog of all underground treasures that are to be used in the national economy. On the example of Siberia, and in particular on the example of the Baikal-Amur Mainline, it became obvious that almost all types of mineral raw materials are complex and require a single development system, i.e., when the main type of mineral is exploited, deposits of associated raw materials should also be involved in the development. In the first years of Soviet power, fifteen to twenty useful elements were extracted from ores, in 1950 - forty-three, in 1960 - already sixty-six, and in the 70s - seventy-four. With the integrated development of deposits, the cost of obtaining raw materials is reduced, and the economic profitability of this process is increased. One of real ways integrated exploitation of subsoil - the creation of territorial-industrial complexes. This is a new, more progressive form of organization of production, designed to make full use of natural storerooms. In the area of ​​the BAM route, the Udokan territorial-industrial complex will be created, which will include a mining and processing plant, a copper smelter, the city of Udokan and other facilities.

Land masses appeared, the formation of which continued into the Proterozoic. As a result, the vast Precambrian Siberian Platform was formed. During the period of Baikal folding, the Yenisei ridge arose, the Turukhansk uplift and the formation of a folded basement ended throughout the entire territory. Two shields - Anabar and Aldan were separated by a deep trough formed in the eastern part of the platform. In the Cambrian period - this is the beginning of the Paleozoic era, the existing land was submerged and covered with the waters of the seas. Marine sedimentary strata accumulated at the bottom of the seas. On the platform margins, salts and gypsum accumulated, or in other words, a platform cover was formed.

The Siberian platform during the Caledonian orogeny is still covered by the sea, and to the north of it, new folded structures were forming. Their formation took place in the archipelago Severnaya Zemlya and in the north of the Taimyr Peninsula. The slow retreat of the sea, characteristic of the Devonian, is associated with the general uplift of the territory. A continental regime is established and a dense network of rivers and lakes is formed. platform, or rather northwestern part, experiences immersion, resulting in the formation of the Tunguska syneclise.

With the manifestation of Hercynian folding, the base of the platform is crushed. Volcanic activity begins with maximum stress in the Triassic. The outpouring of lavas form trap covers, i.e. erupted rocks represented by andesites, dolerites, basalts. Their manifestation is clearly visible in the Tunguska syneclise. Depressions and troughs are filled with lacustrine, river, and delta deposits. In Hercynian time runs active folding, the Byrranga mountains and the North Siberian lowland are formed. In the middle era - the Mesozoic - active tectonic activity is manifested only on the outskirts of the plain.

The geological structure of the territory is represented by 2 large structures:

1. Siberian platform;
2. Taimyr-Khatanga folded region.

ancient Siberian platform retains its flat appearance for more than $600 million years. The platform has two floors - a folded crystalline foundation, composed of gneisses, marble, quartzites, i.e. metamorphosed rocks and a loose cover composed of marine and continental rocks of the Paleozoic and Mesozoic. A $2$ shield and $2$ large ledges formed in the basement of the platform – the Aldan and Anabar shields, the Yenisei ledge, and the Turukhan uplift. Deep depressions separate the basement uplifts, among which the Angara-Lena trough, the Tunguska syneclise, and the Vilyui syneclise stand out.

Taimyr-Khatanga folded region represented by the folded region of Taimyr and Severnaya Zemlya. The northern part of the region is the Caledonides, while the central and southern parts are the Hercynides. The Khatanga depression is the basis of the North Siberian lowland.

Relief of Central Siberia

In the formation of modern relief Central Siberia big role played the events of Alpine folding. Such mountain rises as the Anabar massif, the Yenisei ridge, the Aldan highlands, the Byrranga mountains will correspond to the protrusions of the folded basement. The Leno-Vilyui and North Siberian lowlands are confined to the depressions. The inversion forms include the Tunguska syneclise and the Angara-Lena trough. The lithological composition of the rocks of different ages also big influence for relief. The territory of Central Siberia is mainly occupied by high plateaus and plateaus, minority occurs in mountains and low plains.

The mountains Byrranga belong to the Taimyr-Khatanga folded region and represent a leveled lowland, with a height of $ 800 $ - $ 900 $ m and small pockets of modern glaciation. This is a system of parallel ridges, having a decrease to the west and north. The base of the mountains is of Caledonian and Hercynian age. The mountains experienced numerous secondary uplifts and dislocations.

They stretch for $1100$ km with a width of more than $200$ km and are divided by the valleys of the Pyasina and Taimyr rivers into $3 $parts:

1. The western lowest part has heights of $250$-$320$ m;
2. The middle part with a height of $400$-$600$ m;
3. Eastern part – $600$-$1000$ m.

The southernmost of the ridges - the Main Ridge - is the highest. The Byrranga are the northernmost continental mountain range in the world.

It stretched for $1000$ km North Siberian Plain, which occupies the Pre-Taimyr trough. It has a height of $100$ m and is composed of Quaternary deposits. The plain is swampy and has many lakes of tectonic and glacial origin. The relief of the plain was formed by Quaternary glaciations and marine transgressions. In general, it has a hilly-ridged and hilly-ridged appearance with alluvial depressions and flat accumulative plains. In the east of the North Siberian Lowland there are $2 $ridges - Pronchishchev and Chekanovsky.

In modern relief-forming exogenous processes, the following are of great importance:

1. Erosion;
2. Physical weathering, the cause of which is the sharp continentality of the climate;
3. Permafrost processes and its widespread distribution;
4. Karst phenomena caused by the distribution of carbonate rocks. There are areas of limestone, gypsum, salt karst.

Remark 1

I must say that permafrost slows down modern processes erosion and prevents the development of karst, and this suggests that karst landforms in Central Siberia are not widespread.

The main part of Central Siberia is occupied Central Siberian Plateau, which is based on the Siberian platform. It is characterized by a combination of flat and gently undulating stepped relief. The heights of the plateau gradually decrease to the east, towards the Central Yakut Plain.

The plateau includes:

1. Putorana Plateau;
2. Siverma Plateau;
3. Yenisei Ridge;
4. Irkutsk Plain;
5. Prilenskoe plateau;
6. Central Yakut Plain;
7. Vilyui plateau;
8. Anabar plateau;
9. Central Siberia;
10. Anabar-Olenyok plain;
11. Central Tunguska plateau.

The Central Siberian Plateau is characterized by the elevation and contrast of the relief, which is its main feature. The plateau has significant fluctuations in altitude from $150$ to $2200$ m, with an average height of $500$-$700$ m. The Anabar Plateau, the Aldan Highlands, and the Yenisei Ridge correspond to the protrusions of the platform foundation. In those places where the depressions were located, there are morphostructures prevailing on the plateau - the Central Yakut Lowland, the Irkutsk-Cheremkhovskaya Plain, reflecting the connection of the relief with the ancient structures of the foundation. But, there are also opposite examples, when uplands and plateaus correspond to the deflections of the foundation. For example, the Putorana Plateau and the Syverma Plateau are confined to the Tunguska syneclise. The Angara-Lena trough corresponds to the Angara-Lena plateau.

Minerals of Central Siberia

The bowels of Central Siberia are exceptionally rich in various minerals.

Iron ores. There are different genesis of ores both in the basement and in the platform cover. Magnetites of the South Aldan basin, Angara-Pitsky iron ore basin of the Yenisei Ridge. Iron ores of sedimentary origin are confined to a large synclinorium - the Vilyui and Cannes depressions. Copper-nickel ores, the formation of which is associated with mafic-hyperbasic intrusions that have intruded into the trap series - Norilkoe, Talnakh deposits.

Aldan deposits gold associated with Mesozoic alkaline magmatism. Platinum- the southern part of the Aldan shield. There are placer deposits of platinum river valleys. Maymecha-Kotuiskoye deposit of rare metals.

Nonmetallic minerals:

Indigenous diamond deposits occurring in the basins of the rivers Vilyui, Olenyok, Muna. The main diamond deposits are associated with "explosion pipes" - diatremes. They are filled with kimberlites - this is a brecciated rock, consisting of yellow and bluish clays, including large fragments of volcanic rocks.

Kureyskoye, Noginskoye deposits graphite. These deposits were formed as a result of thermal metamorphism of hard coals. The graphite is of high quality.

Huge reserves rock salt are concentrated in the Usolye-Sibirskoye field. This is the Berezovsky trough in the central part of the Tunguska syneclise. On the northern part of the platform, the Nordvik salt domes of Early Devonian age are known. The Kempendyai salt domes are connected with the Vilyui syneclise.

Two levels are represented on the territory of Central Siberia hard and brown coals. These are the Tunguska coal basin and the Irkutsk-Cheremkhovo and Cannes basins. In the Vilyui syneclise and the Predverkhoyansk foothill trough, there is the Lena coal basin, which is huge in terms of reserves. There are coal deposits on the Taimyr Peninsula. The Middle Paleozoic deposits of the Tunguska syneclise are considered promising hydrocarbon deposits.

Refractory deposits are associated with marine sedimentary rocks. clay and limestone.

WESTERN SIBERIAN PLATFORM (West Siberian Plate), the world's largest young platform, mainly with a Paleozoic folded basement, corresponding to the area of ​​the West Siberian Plain; continues on the shelf of the Kara Sea. Since the beginning of the Mesozoic, the West Siberian Platform has been a large area of ​​subsidence in the north of the Ural-Okhotsk mobile belt with the accumulation of a thick sediment cover. AT structurally The West Siberian platform is a megasyneclise complicated by flexures, brachymorphic uplifts and troughs. The thickness of the sedimentary cover in the northern part of the platform reaches 8 km or more, in the southern part it does not exceed 3 km. The basement of the West Siberian platform is heterogeneous. From the west, the Hercynian folded structures of the Urals submerge under the Meso-Cenozoic cover, from the southwest - the Caledonides of the eastern part of Central Kazakhstan, from the southeast - the salairids of the Kuznetsk Alatau and the Eastern Sayan. The base of the eastern part of the platform is formed by the Baikal folded structures of the Yenisei zone (a continuation of the folded system of the Yenisei Ridge), and to the north - the submerged foundation of the Siberian Platform. The foundation of the central part of the platform is composed of hercynides (the northern extension of the Irtysh-Zaisan folded system); the presence of Precambrian massifs is assumed (Uvat-Khanty-Mansiysk, Barnaul, etc.). The Kustanai saddle separates the West Siberian platform from the Turan platform.

At the base of the platform cover, a complex of terrigenous continental Triassic-Lower Jurassic deposits is developed, filling paleorifts (taphrogens) of submeridional strike - Yamal, Koltogoro-Urengoy, Chelyabinsk, Khudoeyevsky. The deposits of the Lower and Middle Triassic in taphrogens contain traps (platobasalts), the Middle Upper Triassic deposits are predominantly terrigenous, partly coal-bearing (in the Chelyabinsk paleorift). The earth's crust under paleorifts has a reduced thickness (less than 36 km). The Middle Jurassic and younger deposits (plate complex of the cover) occur over the entire area of ​​the West Siberian Platform. These are thin Middle Upper Jurassic deep-water bituminous clays (Bazhenov Formation), Cretaceous - Eocene shallow-marine sands, conglomerates, clays, flasks; Oligoceneogene lacustrine-alluvial deposits. The cover of Quaternary glacial, river, lacustrine-marsh sediments is widely developed.

On the West Siberian platform, deposits of ferruginous quartzites are associated with the Precambrian basement complexes in the south. The oil and gas fields of the West Siberian oil and gas province are of great industrial importance. The rocks of the Lower and Middle Jurassic in the south and southeast of the platform are coal-bearing (Kansk-Achinsk coal basin); coal deposits are found in the Lower Cretaceous deposits in the northeast (near the city of Dudinka), bauxite - in the south (Turgai group of deposits). Deposits of limonite iron ores are known in the Upper Cretaceous section of the Southern Cis-Urals, Kolpashevo Ob region; in the Paleogene of the Urals - sedimentary deposits of manganese ores. Lacustrine Quaternary deposits of the southern part of the platform contain soda, as well as peat deposits. The West Siberian artesian region, unique in size, is confined to the West Siberian platform.

Lit .: Geology and minerals of Russia. St. Petersburg, 2000. Vol. 2: Western Siberia; Khain V. E. Tectonics of continents and oceans (year 2000). M., 2001.