The Urals on Earth are a unique phenomenon.

• And in its role as a planetary seam that once held two great continents together.
• And by the abundance of natural landscapes here, generously scattered throughout its space.
• And in terms of climatic diversity.

Indeed, where else can you find such an edge, at which the headboard would be cooled by the age-old ice of the Northern Ocean, and the foot would be burned by the calcined sands of the deserts? The land, where on the same June day the unsetting sun shines over the blooming polar tundra and the alpine meadows forbs spreads luxuriously. Where you can hunt to your heart's content in cedar trees or, after admiring the slender choirs of elegant birch pegs, stop at a Bashkir nomad camp, drink plenty of chilled kumis, while watching everything around vibrate in the sultry haze of the steppe ...

And now, from these poetic pictures of the Ural Territory, we will have to move on to more prosaic, but very necessary things for our story. It is interesting, I think, to understand for oneself - how did such an unusual natural creation appear on the planet's body, what forces erected it. Therefore, a small excursion into the science that studies the Earth, into geology, is inevitable.

What does modern geology define by the concept of "Ural"?

Strictly speaking, the Urals is a mountainous country with two great plains adjacent to it from the west and east. Why geologists think so, we will discuss later. As mentioned earlier, the Ural mountainous country lies on the planet in a rather narrow strip, the width of which rarely exceeds one hundred and fifty kilometers, but it stretches from the Aral deserts to the Arctic Ocean for more than two and a half thousand kilometers. In this way, it resembles many mountain ranges known on Earth - the Andes, for example. Only the mountains in the Urals, although often rocky, are much lower, less steep, more ordinary, perhaps, than their illustrious counterparts somewhere in the Alps or the Himalayas.

But if the Ural Mountains outwardly do not amaze with anything, then the content of their bowels is completely unique.

Geology of the Ural Mountains

The Urals are world famous for the richness and diversity of their geological structure. This is an irrefutable truth. But it is necessary to realize to the most subtle shade of significance of this fact - the Urals may be the only place on Earth where specialists have found rocks formed in almost all periods of the planet's existence. And minerals, the appearance of which could be due to the existence here (of course, in different time) of all conceivable physical and chemical regimes both in the bowels of the Earth and on its surface. Some kind of utter mishmash of different-aged and diverse geological formations!

But that's not all.

The abundant list of geological formations of the Urals naturally includes a uniquely wide range of the richest deposits of almost all minerals known on our planet. Oil and diamonds. Iron and jasper with marble. Gas and malachite. Bauxites and corundum. And ... and ... and ... The list is endless - not everything is still open, and we still know not all types of minerals.

Ural mountains

2. Geological structure, relief, minerals

The Ural Mountains were formed in the Late Paleozoic during the era of intense mountain building (Hercynian folding). The formation of the Urals mountain system began in the late Devonian (about 350 million years ago) and ended in the Triassic (about 200 million years ago).

Is an part of Ural-Mongolian folded geosynclinal belt. Within the Urals, deformed and often metamorphosed rocks of predominantly Paleozoic age come to the surface. The strata of sedimentary and volcanic rocks are usually strongly crumpled, broken by ruptures, but on the whole form meridional bands, which determine the linearity and zoning of the structures of the Urals. From west to east stand out:

§ Cis-Ural foredeep with a relatively flat bedding of sedimentary strata in the western side and more complex in the eastern;

§ zone of the western slope of the Urals with the development of sedimentary strata of the Lower and Middle Paleozoic, intensively crumpled and disturbed by thrusts;

§ Central Ural uplift, where among the sedimentary strata of the Paleozoic and Upper Precambrian in places emerge more ancient crystalline rocks of the edge of the East European platform;

§ a system of troughs-synclinoria of the eastern slope (the largest are Magnitogorsk and Tagil), filled mainly by Middle Paleozoic volcanic strata and marine, often deep-sea sediments, as well as deep-seated igneous rocks (gabbroids, granitoids, less often alkaline intrusions) breaking through them - i.e. n. the greenstone belt of the Urals;

§ Ural-Tobolsk anticlinorium with outcrops of older metamorphic rocks and widespread development of granitoids;

§ East Ural synclinorium, in many respects similar to the Tagil-Magnitogorsk one.

At the base of the first three zones, according to geophysical data, an ancient, Early Precambrian basement is confidently traced, composed mainly of metamorphic and igneous rocks and formed as a result of several epochs of folding. The most ancient, presumably Archean, rocks come to the surface in the Taratash ledge on the western slope of the Southern Urals. Pre-Ordovician rocks in the basement of synclinoria on the eastern slope of the Urals are unknown. It is assumed that the basement of the Paleozoic volcanogenic strata of synclinoria are thick plates of hyperbasites and gabbroids, which in places come to the surface in the massifs of the Platinum-bearing belt and other related belts; these plates are possibly rejects of the ancient oceanic bed of the Ural geosyncline. In the east, in the Ural-Tobolsk anti-clinorium, outcrops of Precambrian rocks are quite problematic.

Paleozoic deposits of the western slope of the Urals are represented by limestones, dolomites, sandstones, formed in the conditions of predominantly shallow seas. To the east, in a discontinuous strip, deeper-water sediments of the continental slope are traced. Farther east, within the eastern slope of the Urals, the Paleozoic section (Ordovician, Silurian) begins with altered basaltic volcanics and jaspers, comparable to the rocks of the bottom of modern oceans. In places higher in the section, there are thick, also altered spilite-natro-liparite strata with deposits of copper pyrite ores. Younger deposits of the Devonian and partly of the Silurian are represented mainly by andesite-basaltic, andesite-dacite volcanics and graywackes, which correspond to the development of the eastern slope of the Urals to the stage when the oceanic crust was replaced by a transitional crust. Carboniferous deposits (limestones, gray-wackes, acidic and alkaline volcanics) are associated with the latest, continental stage of development of the eastern slope of the Urals. At the same stage, the bulk of the Paleozoic, essentially potassium, granites of the Urals, which formed pegmatite veins with rare valuable minerals, were introduced.

In the Late Carboniferous-Permian time, sedimentation on the eastern slope of the Urals almost stopped and a folded mountain structure was formed here; on the western slope at that time, the Cis-Ural foredeep was formed, filled with a thick (up to 4-5 km) stratum of detrital rocks, carried away from the Urals, - molasse. Triassic deposits have been preserved in a number of depressions-grabens, the emergence of which in the north and east of the Urals was preceded by basaltic (trap) magmatism. Younger strata of Mesozoic and Cenozoic platform deposits gently overlap folded structures along the periphery of the Urals.

It is assumed that the Paleozoic structure of the Urals was formed in the Late Cambrian - Ordovician as a result of the splitting of the Late Precambrian continent and the expansion of its fragments, as a result of which a geosynclinal depression with crust and oceanic sediments in its inner part was formed. Subsequently, the expansion gave way to compression and the oceanic depression began to gradually close and "overgrow" with the newly forming continental crust; the character of magmatism and sedimentation changed accordingly. Modern structure The Urals bear traces of the strongest compression, accompanied by a strong transverse contraction of the geosynclinal depression and the formation of gentle scaly thrust faults - nappes.

The Urals is a whole system of mountain ranges stretched parallel to one another in the meridional direction. As a rule, there are two or three such parallel ridges, but in some places, with the expansion of the mountain system, their number increases to four or more. So, for example, the orographically very complex South Ural is between 55 0 and 54 ° N. sh., where there are at least six ridges. Between the ridges lie vast depressions occupied by river valleys.

The orography of the Urals is closely related to its tectonic structure. Most often, ridges and ridges are confined to anticlinal zones, and depressions - to synclinal zones. Less common is the reversed topography associated with the presence of rocks more resistant to destruction in synclinal zones than in adjacent anticlinal zones. Such a character has, for example, the Zilair plateau, or the South Ural plateau, within the Zilair synclinorium.

Lowered areas are replaced in the Urals by elevated ones - a kind of mountain nodes, in which the mountains reach not only their maximum heights, but also their greatest width. It is remarkable that such nodes coincide with places where the strike of the Ural mountain system changes. The main ones are Subpolar, Sredneuralsky and Yuzhnouralsky. In the Subpolar node, lying at 65 ° N. sh., the Ural deviates from the southwestern direction to the south. Here rises the highest peak of the Ural Mountains - Mount Narodnaya (1894 m). The Middle Urals knot is located about 60 ° N. sh., where the strike of the Urals changes from south to southeast. Among the peaks of this node stands out Mount Konzhakovsky Kamen (1569 m). The South Ural junction is located between 55 0 and 54 0 s. NS. Here, the direction of the Ural ridges becomes, instead of the southwestern, southern, and from the peaks Iremel (1582 m) and Yamantau (1640 m) attract attention.

A common feature of the Ural relief is the asymmetry of its western and eastern slopes. The western slope is gentle, passes into the Russian Plain more gradually than the eastern one, which slopes steeply towards the West Siberian Plain. The asymmetry of the Urals is due to tectonics, the history of its geological development.

Another orographic feature of the Urals is associated with asymmetry - the displacement of the main watershed ridge separating the rivers of the Russian Plain from the rivers of Western Siberia to the east, closer to the West Siberian Plain. This ridge in different parts of the Urals has different names: Uraltau in the Southern Urals, Belt Stone in the Northern Urals. Moreover, it is not the highest almost everywhere; the largest peaks, as a rule, lie to the west of it. Such a hydrographic asymmetry of the Urals is the result of the increased "aggressiveness" of the rivers of the western slope, caused by the sharper and faster uplift of the Cis-Urals in the Neogene in comparison with the Trans-Urals.

Even with a cursory glance at the hydrographic picture of the Urals, it is striking that most rivers on the western slope have sharp, cranked turns. In the upper reaches, the rivers flow in the meridional direction, following longitudinal intermontane depressions. Then they turn sharply to the west, cutting through often high ridges, after which they again flow in the meridional direction or retain the old latitudinal direction. Such sharp turns are well pronounced in Pechora, Shchugor, Ilych, Belaya, Aya, Sakmara and many others. It has been established that rivers cut through ridges in places where fold axes fall. In addition, many of them, apparently, are older than the mountain ranges, and their incision took place simultaneously with the uplift of the mountains.

The low absolute height determines the predominance of low-mountain and mid-mountain geomorphological landscapes in the Urals. The peaks of many ridges are flat, in some mountains they are dome-shaped with more or less soft outlines of the slopes. In the Northern and Polar Urals, near the upper border of the forest and above it, where frost weathering is vigorously manifested, stone seas (turmeric) are widespread. These places are also characterized by upland terraces arising as a result of solifluction processes and frost weathering.

Alpine landforms in the Ural Mountains are extremely rare. They are known only in the most elevated parts of the Polar and Subpolar Urals. The bulk of the modern glaciers of the Urals is associated with these same mountain ranges.

"Glaciers" is not a casual expression in relation to the glaciers of the Urals. Compared to the glaciers of the Alps and the Caucasus, the Ural ones look like dwarfs. All of them belong to the tar and tar-valley types and are located below the climatic snow border. The total number of glaciers in the Urals is 122, and the entire area of ​​glaciation is only slightly more than 25 km 2. Most of them are in the polar watershed part of the Urals between 67 0 - 68 0 s. NS. There are found tar-valley glaciers up to 1.5-2.2 km in length. The second glacial region is located in the Subpolar Urals between 64 0 and 65 ° N. NS.

Most of the glaciers are concentrated on the more humid western slope of the Urals. It is noteworthy that all the Ural glaciers lie in the carats of the eastern, southeastern and northeastern exposures. This is explained by the fact that they are inspired, that is, they were formed as a result of the deposition of blizzard snow in the wind shadow of the mountain slopes.

The ancient Quaternary glaciation was also not very intense in the Urals. Reliable traces of it can be traced to the south no further than 61 ° N. NS. Glacial landforms such as kars, cirques and hanging valleys are quite well expressed here. At the same time, attention is drawn to the absence of sheep's foreheads and well-preserved glacial-accumulative forms: drumlins, ozes and end-moraine swells. The latter suggests that the ice sheet in the Urals was thin and not active everywhere; significant areas, apparently, were occupied by inactive firn and ice.

Ancient flattening surfaces are a remarkable feature of the Ural relief. They were first studied in detail by V.A.Varsanofieva in 1932 in the Northern Urals and later by others in the Middle and Southern Urals. Various researchers in different parts of the Urals count from one to seven flattened surfaces. These ancient leveling surfaces provide compelling evidence of the uneven uplift of the Urals over time. The highest of them corresponds to the most ancient peneplanation cycle falling on the lower Mesozoic, the youngest, lower surface is of Tertiary age.

I.P. Gerasimov denies the existence of uneven-aged surfaces of leveling in the Urals. In his opinion, there is only one flattening surface that formed during the Jurassic-Paleogene and then underwent deformation as a result of recent tectonic movements and erosional erosion.

It is difficult to agree that for such a long time as the Jurassic-Paleogene, there was only one, undisturbed denudation cycle. But I.P. Gerasimov is undoubtedly right in emphasizing the great role of neotectonic movements in the formation of the modern relief of the Urals. After the Cimmerian folding, which did not affect the deep Paleozoic structures, the Urals existed throughout the Cretaceous and Paleogene as a strongly peninsulated country, along the edges of which there were also shallow seas. The Ural acquired its modern mountainous appearance only as a result of tectonic movements that took place in the Neogene and Quaternary periods. Where they reached great scope, now they rise the most. high mountains, and where tectonic activity was weak, little altered ancient peneplains lie.

Karst landforms are widespread in the Urals. They are typical for the western slope and the Cis-Urals, where Paleozoic limestones, gypsum and salts are karsting. The intensity of manifestation of karst here can be judged by the following example: for Perm region 15 thousand karst sinkholes are described on 1000 km 2 surveyed in detail. The largest in the Urals is the Sumgan Cave (South Ural), 8 km long; the Kungur Ice Cave with numerous grottoes and underground lakes is very famous. Other large caves are Divya in the area of ​​the Polyudov Ridge and Kapova on the right bank of the Belaya River.

The Ural Mountains are a treasure trove of various minerals. There are 48 types of minerals in the Ural Mountains.

The Uraltau anticlinorium forms the axial, highest part of the mountain structure of the Urals. It is composed of rocks of the pre-Ordovician complex (lower structural stage): gneisses, amphibolites, quartzites, metamorphic schists, etc. Strongly compressed linear folds are developed in the anticlinorium, overturned to the west or east, which gives the anticlinorium a fan-shaped structure. Along the eastern slope of the anticlinorium, there is the Main Ural deep-seated fault, to which numerous intrusions of ultrabasic rocks are confined. A large complex of minerals is associated with them: deposits of nickel, cobalt, chromium, platinum, and Ural gems. Iron deposits are associated with the strata of the Riphean deposits.

In relief, the anticlinorium is represented by a narrow meridionally elongated ridge. In the south, it is called Uraltau, to the north - the Ural ridge, even further - Belt Stone, Research, etc. This axial ridge has two bends to the east - in the region of the Ufimsky horst and the Bolshezemelsky (Usinsky) arch, i.e. where it bends around the hard blocks of the Russian plate.

The Magnitogorsk-Tagil (Zelenokamenny) synclinorium stretches along the entire Urals up to the coast of the Baydaratskaya Bay. It is composed of the Ordovician-Lower Carboniferous sedimentary-volcanic complex. Diabases, diabase-porphyries, tuffs, various jaspers (green, meat-red, etc.), extensive acidic intrusive bodies (trachytes, liparites), in some places very strongly metamorphosed limestones (marbles) are widespread here. Intrusions of ultrabasic rocks are encountered in the fault zones bordering the synclinorium. All breeds are strongly foliated. Often the rocks have undergone hydrothermal alteration. This is a copper-pyrite strip, where there are hundreds of copper deposits. Deposits of iron ores are confined to the contact of granites with limestones of the Lower Carboniferous. There is alluvial gold and Ural gems (precious and semi-precious stones).

In the relief, this zone is represented by short ridges and separate massifs up to 1000-1200 m and higher, located among vast depressions along which river valleys are laid.

The Ural-Tobolsk, or East Ural, anticlinorium can be traced along the entire folded structure, but only its southern part is part of the Ural mountainous country, since to the north of Nizhny Tagil it is hidden under the cover of the Meso-Cenozoic cover of the West Siberian plate. It is composed of shale and volcanogenic strata of the Paleozoic and Riphean, penetrated by intrusions of granitoids, predominantly of the Upper Paleozoic age. Intrusions are sometimes enormous. Deposits of high quality iron and gold are associated with them. Short chains of ultrabasic intrusions can also be traced here. Ural gems are widespread.

In relief, the anticlinorium is represented by a ridged strip of eastern foothills and the Trans-Ural peneplain. Ayatskiy synclinorium is part of the Urals only with its western wing in the extreme south of the region. To the north and east, it is overlain by the Meso-Cenozoic sedimentary cover. The Siclinorium is composed of highly fragmented and crumpled deposits of the Paleozoic, broken by igneous rocks of different composition, protruding from under the cover of Paleogene deposits. There are narrow graben-like depressions filled with Triassic and Lower Jurassic deposits of the Turin and Chelyabinsk series. Coal deposits are associated with the latter. In relief, the Ayatsky synclinorium is presented as part of the Trans-Ural plateau. Thus, the morphotectonic zones of the Urals differ from each other in geological structure, relief and a set of minerals, therefore, the natural zonal structure of the Urals is perfectly readable not only on a geological map, but also on mineral and hypsometric maps.

In the relief of the Urals, two strips of foothills (western and eastern) and a system of mountain ranges located between them are clearly distinguished, stretching parallel to each other in the submeridional direction, according to the strike of tectonic zones. There may be two or three such ridges, but in some places their number increases, up to six or eight. The ridges are separated from each other by vast depressions, along which rivers flow. As a rule, the ridges correspond to anticlinal folds composed of older and stronger rocks, while the depressions correspond to synclinal folds.

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The formation, development of the Ural mountainous country took place over hundreds of millions of years.
There are several major stages of its development. At the earliest stage of development, in the Late Archean (about 3 billion years), this part of the land, which was later called the Urals, becomes a tectonically active zone. Deep cracks (faults) are laid in the earth's crust, along which basalt lavas pour out onto the surface. The igneous melts that did not reach the surface crystallized at depths of 5-10 km, forming large intrusive massifs. Clastic sedimentary rocks accumulated in shallow sea basins occupying low relief areas.
Then comes the time of relative rest. Paleoural on a short time becomes a tectonically calm country. About 2 billion years ago, tectonic movements resume from new strength... Extended zones of deep faults are again formed over a large area. Volcano chains grow along them. Huge, thousands of kilometers of land, sag and are flooded by the sea. For a long time, this part of the Paleoural becomes an ocean floor. It was here, on the western "shoulder" of the future Ural Mountains, that huge strata (more than 10-12 km) of sedimentary rocks could accumulate: limestones, dolomites, clay, calcareous and carbonaceous shales, sandstones and conglomerates. About 900 million years ago, the accumulated masses of sedimentary and volcanic rocks are crushed into folds by the giant forces of the Earth and form the first mountain peaks of the Urals.
About 600 million years ago, the Urals again appear as a tectonically calm country. Land prevailed. Shallow warm seas occupied small areas. The inhabitants of these seas were sponges, archeoceates, and other, now extinct, organisms, the remains of which have survived in the strata of sedimentary rocks.
In the Paleozoic era, active tectonic movements covered the eastern areas of the Paleoural. Extensive valleys (rifts), accompanied by deep faults, are formed alternately in different parts of this territory, as if moving apart, expanding it. Volcanic activity resumes. Volcanic belts cover vast areas. Most of the volcanoes were marine, so the products of volcanic activity (lavas, tuffs, bombs) were often mixed with sediments that accumulated in the same basins. The vast Ural paleoocean extended to the east for at least 1,500 km.
About 400 million years ago, volcanic islands were formed in this paleoocean, almost the same as today's Kuril and Japanese islands. The remains of such an "island arc" can be seen today in the Magnitogorsk region.
In the Carboniferous (350-290 Ma), this part of the land begins to rise. Sea waters are receding. Oceanic rocks come to the surface of the day. Huge strata of marine and continental sediments, volcanic rocks of various compositions at the end of the Permian period (about 240 million years ago) become high Ural mountains, stretching from northern seas to the southern steppes by almost 2500 km. The formation of the mountains was accompanied by the introduction of large masses of granites, granodiorites, syenites, which not only complicated geological structure Urals, but also caused the appearance of many mineral deposits.
The Urals are gradually becoming a tectonically calm, stable area of ​​the Earth - a platform, but it is still far from complete calm.
The Ural Mountains became active again during the era of the so-called Cimmerian folding (240-100 million years ago). Then, on the eastern slope of the Ural Mountains, large, extended faults of the near-meridional direction formed, along which the outpouring of basaltic lavas began. Near modern Chelyabinsk, a trough with a depth of up to 4000 m and a length of up to 140 km has formed, which is called the Chelyabinsk graben.
In this trough, for 40–45 million years, already in the Mesozoic era, thick layers of coals and their host rocks were formed: sandstones, siltstones, shales.
For the last 160-155 million years, the territory of the Urals, including the South, has been tectonically stable. The Ural mountains are slowly collapsing under the influence of surface forces. In place of the high, once snow-capped peaks, a rather flat plain is formed, called the Trans-Ural peneplain.
The totality of features (composition and origin of rocks, their age, degree of tectonic fragmentation) makes it possible to divide the Ural country into a number of more or less large zones (geological structures). They all formed in the Paleozoic era. From west to east stand out:
I. Pre-Uralian trough.
II. West Ural outer folding zone.
III. Central Ural uplift.
IV. Magnitogorsk trough, Magnitogorsk volcanic belt.
V. East Ural zone of troughs and uplifts.
Vi. Trans-Ural uplift.

Pre-Ural trough

The eastern part of this structure is in the far west Chelyabinsk region, in the area of ​​Ashi. It is composed of limestones and marls of the Lower Permian age, lying almost horizontally - 1-5 °. Crystalline, more ancient rocks lie here at great depths. The eastern border runs along a fault oriented almost parallel to the Saldybash River, which flows into the Sim River.

West Ural fold zone

This structure covers the territory of Nyazepetrovsky, Satkinsky, Ashinsky districts and the vicinity of Ust-Katav. In the area of ​​Nyazepetrovsk geological formations elongated meridionally, and in the area of ​​the village. Ailino, Kropachevo, Minyara acquire an almost latitudinal direction.
All systems of the Lower and Middle Paleozoic are represented here.
Cambrian rocks (570-500 Ma) - conglomerates, sandstones, mudstones - can be observed northwest of the village. Termininevo. On the river Nyaza, north of Nyazepetrovsk, and along the Bardymsky ridge, Ordovician rocks are exposed - basalts and their varieties, as well as tuffs, tuffaceous sandstones, siliceous schists, among which there are interlayers of marble.
Silurian formations (440-410 Ma) - siliceous, clayey, carbonaceous-argillaceous shale, volcanic tuffs and limestones - also compose the Bardymsky ridge and a wide strip west of it. There are many sandstones and siltstones here.
Devonian formations (410-350 Ma) in this zone are represented by limestones with the fauna of crinoids, foraminifera, corals and ostracods, indicating that the rocks containing them are of marine origin. In the area of ​​the village. Ailino, Landmark Log in the Devonian section, clastic rocks can be observed. There are limestones and marls here. It is among them that there are bauxites (aluminum ores) mined at the South Ural bauxite mines (YuUBR). Carboniferous rocks (350-285 Ma) in the western folding zone are also mainly carbonate - limestones, dolomites, marls.

Central Ural uplift

This complexly constructed zone stretches along the entire Urals for more than 2000 km. On the territory of the region, it is traced for 250 km from the southwest to the northeast. It covers the territory of Katav-Ivanovsky, Satkinsky, Kusinsky districts, as well as the vicinity of Zlatoust and Verkhny Ufaley. In the KatavIvanovsk area, the width of the structure is 120 km, and in the north, in the Verkhny Ufaley area, it is only 25 km.
This structure is composed of the most ancient rocks of the Urals, whose age reaches 2.6-3 billion years, deeply altered volcanic and clastic formations, transformed into amphibolites, gneisses, migmatites, and quartzites. These rocks are widespread west of the Upper Ufaley and Karabash. Younger (1.5-0.9 billion years) are considered rocks that make up a number of strata that have received purely South Ural names - Aiskiy, Satka, Bakal and others. These strata include argillaceous and carbonaceous shales, sandstones, siltstones, limestones and dolomites, which compose strata of huge thickness.
A complete section of the Lower Riphean rocks (~ 900 Ma) is presented in the rocks of the right bank of the Ai River, above the railway bridge in the city of Kus (dolomites, limestones, shales). In the dolomites, here you can observe the remains of colonies of blue-green algae (stromatolite).
Crystalline schists containing rare minerals such as garnet and staurolite are exposed on the Otklikny Ridge (Taganai). In the same place, on Taganai, near Zlatoust, one can observe such rare rocks as quartzites with inclusions of micaceous and ferruginous minerals, called taganaite (aventurine).
There are very few volcanic and igneous rocks in this zone. The latter include the Kusinskaya gabbro intrusion (a dike up to 100 km long), the Berdyaushsky granite massif (rapakivi). There are also well-known mineralogical mines - Akhmatovskaya, Maksimilyanovskaya; the world famous Bakalskoe iron ore and Satkinskoe magnesite deposits are located.
The eastern boundary of the structure runs along the Main Ural fault. This complex zone has been traced for thousands of kilometers throughout the Urals. Within the region, it stretches from the village of Leninsk in the south through Miass, Karabash to the north to the very border with the Sverdlovsk region. The width of this ancient tectonic zone is from 10 15 km to several hundred meters. Along it, the rock complexes of the western slope of the Urals are joined with the complexes of the eastern slope.
Throughout its entire length, the Main Ural Fault can be traced along the observed here extended, ribbon-like (in plan) intrusions of ultrabasic rocks - dunites, peridotites and serpentinites formed along them. This belt stretches for more than 2000 km. Ultrabasic rocks and blocks of Paleozoic sedimentary and volcanic rocks located between them sometimes form a tectonic mixture called melange.

Magnitogorsk trough (volcanic belt)

From the east, the Magnitogorsk Trough is adjacent to the Main Ural Fault - a large structure stretching almost meridionally for 500 km from the southern to northern border of the region. At the latitude of Baimak, Magnitogorsk, the width of the structure is 90-100 km, and in the Miass, Karabash region, it is 1-2 km. It covers ten districts of the region.
The most ancient rocks here are Silurian, the outcrops of which are observed in the northern, narrowest part of the structure. Devonian deposits in the Magnitogorsk trough are presented in full. These are mainly volcanic rocks - lavas and accompanying tuffs. Both lavas and tuffs have different chemical and mineralogical compositions. Among them are acidic (rhyolites), medium (andesites), basic (basalts) products of volcanism. They form thick strata - up to 3-5 km, in which there is a close interlayering of volcanic products with typical marine formations - limestones, sandstones, cherts, jaspers, as well as rocks of a mixed composition - tuffaceous sandstones, tuff gravelites, tuffites and other rocks.
The ruins of volcanic structures of that time, containing their marine sediments, often containing marine fauna, can be observed and studied on the day surface in different parts of the region.
Natural outcrops of Devonian volcanics, limestones, clastic rocks are in the vicinity of the village. Mezhozerny, on the ridges of Irendyk and Kumach (western border of the region), along the banks of Gumbeyka, Kurosan, Urlyadov, in the vicinity of the village. Balkans (Nagaybaksky, Agapovsky regions) and many other places.
Sections of the Carboniferous rocks - lavas of various composition, their tuffs and various sedimentary formations - can be observed in the vicinity of Magnitogorsk, along the Khudolaz and Ural ("Seven Brothers") rivers, and many other places. Carboniferous sediments, the thickness of which reaches many hundreds of meters, fill the entire central part of the trough. The youngest rocks here are limestones, sandstones and conglomerates with the remains of marine animals (shells), exposed along the banks of the rivers: Ural, Khudolaz and B. Kizil.
Sedimentary, volcanic rocks filling the Magnitogorsk trough are broken by tectonic faults of various directions, broken through by intrusions of igneous rocks - granites, granodiorites, syenites, gabbros. In such places were formed large deposits iron ores (Magnitogorsk, M. Kuibas). Volcanic processes at the bottom of the Devonian paleoocean contributed to the formation of pyrite deposits of copper and zinc ores being mined today (Uchalinskoe, Sibayskoe, Molodezhnoe, Alexandria, Uzelginskoe and other deposits).
The East Ural zone of troughs and uplifts is traced in a wide strip across the entire South Urals. The width of this structure is 60-75 km. It covers the central regions of the region - from Kaslinsky in the north to Bredinsky in the south.
The oldest rocks here are metamorphic, including garnet-bearing shales, the outcrops of which can be seen in the vicinity of the village. Larino, Kochnevo (Uysky district), on Mount Igish, south of Miass.
Ordovician formations, both volcanic and volcanic-detrital, are much more widespread in this structure. They were found on Mount Mayachnaya to the northwest of Bred (tuff conglomerates, tuff sandstones, quartzite sandstones), as well as along the Sredniy Toguzak River near the village. Bolshevik. Basalt lavas are deposited here, pouring out onto the seabed. Among the lavas there are interlayers of red jasper with the remains of marine fauna. In the Silurian, this part of the Urals was also the seabed.
In the north of the region, sections with fragments of Silurian deposits can be observed along the Bagaryak, Sinara rivers, near the village. Pervomaisky (Sosnovsky district), in the vicinity of the village. Bulatovo (Uysky district) and in other places (limestones, clay shales, conglomerates, sandstones).
Devonian and Carboniferous deposits are very widespread in this zone. Rocks of the Devonian system are especially fully represented in the sections along the Kurosan River, in the vicinity of the village. Arsinsky, Sukhteli. Siliceous schists, jaspers, and tuffites are interspersed here with diabases, basalts, their tuffs and breccias. Volcanic and sedimentary rocks of the most diverse chemical composition and origins are described in the Argayash region; along the Zyuzelga river, east of the village. Dolgoderevensky, along the Sanarka and Uvelke rivers to the southeast of the Plast. Carboniferous (carboniferous) deposits in this structure are distributed over vast areas in the southern regions of the region (Chesmensky, Kartalinsky, Bredinsky). Marls, limestones and various detrital rocks and shales with carbonaceous particles are widely represented here. The latter are especially numerous, since at that time (350 million years ago) tropical forests grew in the Southern Urals, ferns, calamites, lepidodendrons, sigillaria and other plants grew in them. In some places (Bredinsky district), they formed coal deposits, but, in general, the remains of the carboniferous flora were turned into carbonaceous, graphite dust that paints sedimentary and metamorphic rocks black.
Volcanic rocks - basalts, rhyolites, andesites - are much less here than in the Devonian sections. Fragments of geological sections of the Carboniferous in this structure are sufficient: along the rivers Verkhniy, Nizhniy Toguzak, Uy (village Osipovka), separate large ravines south of the village. Brady, in the vicinity of Plast, along the rivers Kabanka and Uvelka and in other places.
The entire structure as a whole is saturated with intrusive formations - mainly granites, diorites, syenites, which make up dozens of large and small massifs of various configurations.
This chain of massifs, traced through the entire Urals, was named "the granite axis of the Urals". Granite massifs stretch from north to south across the entire region: Yugo-Konevsky, Kaslinsky, Argazinsky, Sultaevsky, Chelyabinsky, Sanarsky, Demarinsky, Borisovsky, Plastovsky, Kaslinsky, Chesmensky, Chernoborsky, Dzhabyk-Karagaysky, Suunduk and many others. The area of ​​the largest massifs - Chelyabinsk and Dzhabyk-Karagaysky - significantly exceeds 1000 sq. km. The lower boundary of the massifs, according to geophysical data, is located at depths of 5-11 km. The intrusions themselves, their host rocks, are dissected by a large number of dikes, veins of the most varied composition, including quartz ones.

Trans-Ural uplift

The easternmost geological structure in the region is the Trans-Ural uplift. This structure covers the eastern regions - from Kunashak in the north to Troitsky and Varna in the south. About 90% of the area is covered by horizontally lying Meso-Cenozoic rocks - from the Upper Cretaceous to the Upper Neogene (100-2 million years).
Paleozoic formations lie at a depth of 5-100 m. They can be observed only along the banks of individual rivers. The most interesting and complete sections were opened along the Uvelka, Sanarka and Uyu rivers near Troitsk. Here, the width of the structure is about 40 km.
The oldest of the Paleozoic rocks, the Cambrian, have been established along the Sanarka River, in the Kuvay Gully. These are variegated shales and limestones. Remnants of archeoceates - benthic organisms of that distant epoch - were found in limestones. This outcrop of Cambrian rocks is the only one in the Southern Urals and one of very few in the Urals in general.
Ordovician formations in this zone are much more widespread. Gray quartz sandstones, green and gray metamorphic shales, quartzites and basalts are widely represented in sections along the Uy and Uvel'ka rivers in Troitsk itself and to the east of it, to the village of Bobrovka. Remains of ancient crustaceans - trilobites and brachiopod shells - were found in clayey rocks on the western outskirts of Troitsk. All the described Ural structures were formed in the pre-Paleozoic and Paleozoic times, when the Urals were an active zone of folding and volcanism. In the next 160 million years (to the present day), the Urals developed in a relatively calm platform mode.
According to geological data, abrupt tectonic rearrangements did not occur in the Southern Urals, but slow oscillatory movements accompanied by small uplifts or subsidence of individual regions continued and continue.
In the Upper Cretaceous (about 100 Ma), the subsidence of the eastern part of the territory leads to marine transgression. The sea was advancing from the northeast, from the side of Tyumen. Its western border - very winding, with deep bays - was established approximately along the line of the village. Bagaryak - Lake B. Kuyash - Chelyabinsk - Yuzhnouralsk - Chesma - Kartaly - Bredy (to the east). Marine sediments - opokas, diatomites, sandstones, conglomerates, tripoli, marls - formed horizontally lying layers overlapping the rocks of the Paleozoic Urals. The thickness of these sediments in the eastern part of the Troitsk region, according to drilling data, is 100-300 m.
Both Paleozoic and Mesozoic formations already in the Quaternary time (1.5-2 million years) were overlapped by continental, formed on land, loose rocks - clays, sands, loams, formed as a result of the work of wind, water, and the sun.

The history of the development of the Urals, including the Northern Urals, determined the presence of two substantially different complexes (structural layers) in the structure of folded structures. The lower complex (stage) is represented by pre-Ordovician strata. The rocks of this complex are exposed in the cores of large anticlinoria. They are represented by various Archean gneisses and crystalline schists. In some places there are metamorphic schists, quartzites and marbles of the Lower Proterozoic. Above these strata, there are Riphean (Upper Proterozoic) deposits, reaching a thickness of 10-14 km and represented by four series. A feature of all these series is rhythm. At the base of each series, conglomerates, quartz sandstones and quartzites occur, passing higher into siltstones, clayey and phyllite shales. At the top of the section, they are replaced by carbonate rocks - dolomites and limestones. The section of the Riphean deposits is crowned by typical molasse (Ashinskaya series), reaching 2 km.

The composition of the Riphean sediments indicates that during their accumulation there was an intensive subsidence, which was repeatedly replaced by short-term uplifts, leading to a facies change of sediments. At the end of the Riphean, Baikal folding occurred and uplifts began, which intensified in the Cambrian, when almost the entire territory of the Urals turned into dry land. This is evidenced by the very limited distribution of Cambrian deposits, represented only by the Lower Cambrian greenschists, quartzites and marbles, which are also part of the lower structural complex.

Thus, the formation of the lower structural stage was completed by the Baikal folding, which resulted in the appearance of structures that differ in their plan from the later Uralic structures.

The upper structural stage is formed by deposits from the Ordovician to the Lower Triassic, which are subdivided into geosynclinal and orogenic complexes. These deposits accumulated in the Ural Paleozoic geosyncline and the folded area that arose within it. The tectonic structures of the modern Northern Urals are associated with the formation of this particular structural stage.

The Northern Urals is an example of one of the largest linear folded systems stretching for thousands of kilometers. It is a meganticlinorium, which consists of alternating anticlinoria and synclinoria, oriented in the meridional direction. The modern structural plan of the Northern Urals was laid down already in the Ordovician, when all the main tectonic zones arose in the Paleozoic geosyncline, and the stratum of Paleozoic deposits reveals a clear facies zoning. However, at the same time, there are sharp differences in the nature of the geological structure and development of tectonic zones of the western and eastern slopes of the Northern Urals, which form two independent mega-zones. They are separated by a narrow (15 - 40 km) and very consistent along strike Uraltau anticlinorium (in the north it is called Harbeysky), bounded from the east by a large deep fault - the Main Ural fault, to which a narrow strip of ultrabasic and basic rocks is confined. In some places, the fault is a strip 10-15 km wide.

The eastern megazone, maximally bent and characterized by the development of basic volcanism and intrusive magmatism, developed in the Paleozoic as an eugeosynclinole. It has accumulated thick strata (over 15 km) of volcanic-sedimentary deposits. This megazone is part of the modern Northern Urals, hidden under the Meso-Cenozoic cover of the West Siberian Plate.

The western megazone is practically devoid of igneous rocks. In the Paleozoic, it was a myogeosynclinal, where the accumulation of marine terrigenous and carbonate deposits took place. In the west, this megazone passes into the Cis-Ural foredeep. From the point of view of supporters of the lithospheric plate hypothesis, the Main Ural Fault fixes the subduction zone of the oceanic plate moving from the east under the eastern coloration of the East European Platform. The Uraltau anticlinorium is confined to the marginal part of the platform and corresponds to the ancient island arc, to the west of which the trough zone developed on the continental crust (myogeosyncline), the oceanic crust was formed to the east (up to the Middle Devonian), and later the granite layer in the eugeosyncline zone.

At the end of the Silurian, the Caledonian folding occurred in the Ural geosyncline, which covered a significant territory of the Urals. Back in the Devonian, subsidence resumed. The main folding was the Hercynian. In the eastern megazone, it occurred in the middle of the Carboniferous and manifested itself in the formation of strongly compressed, often overturned folds, thrusts, accompanied by deep fractures and the introduction of powerful granite intrusions. Some of them are up to 100-120 km long and up to 50-60 km wide.

The orogenic stage began in the eastern megazone from the Upper Carboniferous. The young folded system located here supplied clastic material to the marine basin preserved on the western slope, which was a vast foothill trough. As the uplifts continued, the trough gradually migrated to the west, towards the Russian plate, as if "rolling" on it.

The Lower Permian deposits of the western slope are diverse in their composition: carbonate, terrigenous and halogen, which indicates the retreat of the sea in connection with the ongoing mountain building in the Northern Urals. At the end of the lower Perm, it spread to the western megazone. Folding here was less vigorous. Simple folds predominate, thrusts are rare, and intrusions are absent.

The tectonic pressure, which resulted in folding, was directed from east to west. The foundation of the East European Platform hindered the spread of folding; therefore, in the regions of its eastern protrusions, the folds are most compressed, and in the strike of the folded structures, bends flowing around them are observed.

Thus, in the Upper Permian, already throughout the entire territory of the Urals, a young folded system existed, which became the arena of moderate denudation. Even in the Cis-Ural foredeep, sediments of this age are represented by continental facies. In the far north, their accumulation lasted until the Lower Triassic.

In the Mesozoic and Paleogene, the mountains under the influence of denudation collapsed, decreased, and extensive surfaces of leveling and weathering crust were formed, with which placer deposits of minerals are associated. And although the tendency towards the uplift of the central part of the country continued, which contributed to the exposure of Paleozoic rocks and the relatively weak formation of loose deposits, as a result, the downward development of the relief prevailed.

In the Triassic, the eastern part of the folded structures sank along the fault lines, i.e. the separation of the Ural folded system from the Hercynian structures of the basement of the West Siberian plate took place. At the same time, in the eastern megazone, a number of narrow, submeridionally elongated graben-like depressions arose, filled with continental clastic-volcanic strata of the Lower-Middle Triassic (Turin Group) and a continental coal-bearing formation of the Upper Triassic, and in some places also of the Lower-Middle Jurassic (Chelyabinsk Group).

Towards the end of the Paleogene, in the place of the entire Urals, a peneplain plain stretched, more elevated in the western part and lower in the eastern, periodically overlapping in the extreme east by thin marine sediments in the Cretaceous and Paleogene.

Differentiated tectonic movements were observed in the Urals in the Neogene-Quaternary. There was a crushing and movement of individual blocks to different heights, which led to the revival of the mountains. The western megazone, including the Uraltau anticlinorium, is more elevated and characterized by mountainous relief almost throughout the entire length of the Urals, while the eastern megazone is represented by a peneplain or shallow hummock with separate mountain ranges (eastern foothills). Along with ruptured dislocations, the leading role among which was played by longitudinal faults, latitudinal undulating deformations appeared in the Urals - part of similar waves of the East European and West Siberian plains. The consequence of these movements was the alternation of increased (corresponding to the crests of waves) and lower (corresponding to the base) sections of the mountains along their strike (orographic regions). In the Northern Urals, the correspondence of the geological structure to the structure of the modern surface is clearly traced.

It is characterized by a longitudinal-zonal structure. Six morphotectonic zones replace each other here from west to east. Each of them is characterized by its own history of development, and, consequently, by deposits of a certain age and composition, a combination of minerals and relief features.

The synclinorium zone of the western slope is directly adjacent to the Cis-Ural foredeep. It is folded sedimentary rocks Paleozoic. The youngest of them - carbonic (mainly carbonate) are common in the western part, adjacent to the foredeep. To the east, they are replaced by Devonian shales, Silurian carbonate strata and rather heavily metamorphosed Ordovician deposits with traces of volcanism. Dikes of igneous rocks are found among the latter. The amount of volcanic rocks increases to the east.

In relief, the anticlinorium is represented by a ridged strip of eastern foothills and the Trans-Ural peneplain. The Northern Urals is overlain by the Meso-Cenozoic sedimentary cover. The Northern Urals begins with Mount Telpoziz and ends with Konzhakovsky Kamen (1569 m). The height of the ridges here is less than in the Subpolar Urals and averages up to 1000 m, but in the northern and southern parts increases.

The Middle Urals stretches to Mount Yurma. This is the lowest part of the mountains. Average heights here are 500-600 m. Only Mount Oslyanka in its northern part reaches 1119 m, all other peaks are below 1000 m. The mountains here form an arc, slightly curved to the east.

The prevailing type of morphostructures in the Northern Urals are revived folded-block mountains on the pre-Paleozoic and Paleozoic basement.

Morphostructures created under the joint influence of endogenous and exogenous processes are complicated by smaller relief forms created by exogenous relief-forming processes. The imposition of various morphosculptures on morphostructures creates all the diversity of the relief of the Northern Urals.

In the north of the Urals, erosional relief prevails. The main erosional forms here are river valleys. The Urals are characterized by the displacement of the main watershed ridge to the east of the axial part of the mountains, which is one of the manifestations of the asymmetry of the mountain structure. The most complex hydrographic pattern and high density of the river network are characteristic of the western slope of the mountains.

Many rivers were laid down during the period of the descending development of the mountains and the formation of the ancient leveling surface. They were confined to the cyclinal troughs, to belts of softer, more susceptible to destruction of rocks, therefore, they had a general Ural, submeridional direction. During the period of activation of the Neogene-Quaternary movements, the formation of faults and differentiated uplifts, mainly of small amplitude, transverse sections of river valleys were formed, confined to faults or depressions of the axes of anticlinal folds. Therefore, many rivers of the Northern Urals have a cranked pattern: Ural, Sakmara, Belaya, Ai, Kosva, Vishera, Pechora, Ilgch, Shchugor, etc. In longitudinal depressions they have wide valleys, and when crossing mountain ranges they are narrow and steep.

Many rivers were founded during the period of the descending development of the mountains and the formation of the ancient leveling surface. They were confined to the cyclinal troughs, to belts of softer, more susceptible to destruction of rocks, therefore, they had a general Ural, submeridional direction. During the period of activation of the Neogene-Quaternary movements, the formation of faults and differentiated uplifts, mainly of small amplitude, transverse sections of river valleys were formed, confined to faults or depressions of the axes of anticlinal folds. Therefore, many rivers of the Urals have a cranked pattern: Kosva, Yayva, Vishera, Pechora, Severnaya Sosva, etc. In longitudinal depressions they have wide valleys, and when crossing mountain ranges they are narrow and steep.

The Urals are located in the inland border zone of the earth's crust between the ancient Russian platform and the young West Siberian plate. Tectonically, the Urals is a large meganticlinorium, consisting of a system of anticlinoria and synclinoria. In the cores of the anticlinoria, the most ancient rocks emerge - crystalline schists, quartzites, and granites. The synclinoria have thick strata of sedimentary and volcanic rocks.

Large anticlinoria and synclinoria successively replace each other from west to east.

IzonePre-Ural foredeep- transitional geostructure of the Russian platform and folded structures of the Urals. It is composed of sedimentary rocks of the Upper Paleozoic age (limestone, shale, sandstone, gypsum-bearing and salt-bearing strata).

The Uralian trough is connected in the north by lenses. The deflection is divided by transverse projections into separate depressions.

Mineral resources: oil, coal, potash salts (Solikamsk, Bereznyaki), pyrite, peat, cuprous sandstones.

IIzone.The most ancient zone of the western structures.

a). The zone of marginal anticlinoria (Bashkirian) is composed of heavily metamorphosed sandstones, conglomerates, shales.

b). The shale synlinoria zone is composed of sandstones and shales of the Lower and Middle Paleozoic.

IIIzone.Central Ural anticlinorium(along the entire length - Belt Stone, Ural-Tau, Ufaleiskaya) - the axial strip of the Urals. It is composed of Proterozoic and Lower Paleozoic metamorphic rocks - gneisses, amphibolites, quartzites. In the eastern part of the central anticlinorium, the main Ural deep-seated fault passes, along which numerous intrusions take place. Nickel and platinum mineralization, aluminum ores, polymetals, and iron are associated with them.

Zone IV is the eastern zone of tectonic structures.

a). Magnitogorsk-Tagil (earth-stone) synclinorium. It is composed of sedimentary (limestone, shale, jasper) and volcanogenic rocks of the Middle Paleozoic. Copper deposits and ornamental stones are confined to the zone. (Malachite - 57% Cu, Azurite - 55% Cu).

b). East Ural anticlinorium - eastern slope, expressed in the South and Middle Urals. It is composed of volcanic rocks of the Lower Paleozoic of the Hercynian and Caledonian ages and more ancient age. Deposits of gold and gems (topaz, amethyst, emerald, tourmaline, ruby, titanium-magnetite, manganese, iron ores, magnetic, non-ferrous metals) are associated with them.

v). East Ural synclinorium. Expressed only in the Southern Urals. To the north and south it plunges under the strata of Meso-Cenozoic rocks. It is composed of strongly crumpled Paleozoic rocks broken by magmatic intrusions. Developed Mesozoic coal-bearing strata, asbestos.

OROGRAPHY OF THE URALS.

Orographically, the Ural is a system of meridional ridges, parallel to each other. The ridges are separated by intermontane depressions. In narrow places the number of ridges is 2-3 in places of expansion up to 6 (South Urals).

The Urals are asymmetric: the western is gentle, the east is steep. Orographia is closely related to tectonics, especially in the west. Anticlinal zones - ridges; synclinal - depressions. The submeridional strike of morphostructures reflects the regular change of tectonic structures from west to east.

1) .Preuralia - corresponds to an elevated plain with a characteristic ridged relief, deeply dissected by rivers. There is developed kars - carbonate, gypsum, salt.

2). Central Ural anticlinorium - corresponds to the main watershed ridge. Its height ranges from 850 m to 1800 m. Towards the center, it decreases. It has a different name in different parts. The main watershed ridge is displaced closer to the West Siberian Plain. It is not the highest in the Urals. The largest peaks lie to the west.

3). Eastern morphostructural zone - represented by low mountains, small hills with a significant distribution of denudation, denudation-accumulative and accumulative plains. A cover of loess loams is widespread on the plains.

The low absolute height determines the dominance in the Urals of low-mountain and medium-mountain geomorphological landscapes. The tops are shallow or flat.

The relief of the Urals depicts a different interaction of endogenous and exogenous forces. The endogenous factor hardly changes when moving from north to south. Only the exogenous factor changes: it changes from north to south.

Frost weathering is vigorously manifested in the northern part of the Urals. Stone fields - kurums - are widespread.

Solifluction processes are characteristic - permafrost. Here are the main glaciers of the Urals. Glaciers are dwarfs of the tar and carrovo-valley type. The modern forms of the glacier are well-pronounced kars, circuses. There are very few ancient glacial forms, since the Quaternary glaciation was thin.

1). The main exogenous agent is flowing waters in combination with slope processes, in the south there are aeolian processes (arid morphosculpture).

2). Karst relief in the Urals and on the western slope is associated with the lithological composition of rocks. Karst caves are widespread: Kungur ice, Divye (halls, galleries).