The West Siberian Plain is of the accumulative type and is one of the largest low-lying plains on the planet. Geographically, it belongs to the West Siberian plate. On its territory there are regions of the Russian Federation and the northern part of Kazakhstan. The tectonic structure of the West Siberian Plain is ambiguous and diverse.
Russia is located on the territory of Eurasia, the largest continent on the planet, which includes two parts of the world - Europe and Asia. The tectonic structure of the Ural Mountains separates the cardinal directions. The map makes it possible to clearly see the geological structure of the country. Tectonic zoning divides the territory of Russia into geological elements such as platforms and folded areas. The geological structure has a direct connection with the surface topography. Tectonic structures and landforms depend on the region they belong to.
Within Russia there are several geological regions. The tectonic structures of Russia are represented by platforms, folded belts and mountain systems. On the territory of the country, almost all areas have undergone folding processes.
The main platforms within the country are East European, Siberian, West Siberian, Pechora and Scythian. They, in turn, are divided into plateaus, lowlands and plains.
Relief of Western Siberia
The territory of Western Siberia is sinking stepwise from south to north. The relief of the territory is represented by a wide variety of forms and is complex in origin. One of the important criteria of relief is the difference in absolute elevations. On the West Siberian Plain, the difference in absolute elevations is tens of meters.
The flat terrain and slight elevation changes are due to the small amplitude of plate movement. On the periphery of the plain, the maximum amplitude of uplifts reaches 100-150 meters. In the central and northern parts, the amplitude of the subsidence is 100-150 meters. The tectonic structure of the Central Siberian Plateau and the West Siberian Plain in the late Cenozoic was relatively calm.
Geographical structure of the West Siberian Plain
Geographically, in the north the plain borders on the Kara Sea, in the south the border runs through the north of Kazakhstan and covers a small part of it, in the west it is controlled by the Ural Mountains, in the east by the Central Siberian Plateau. From north to south, the length of the plain is about 2500 km, the length from west to east varies from 800 to 1900 km. The area of the plain is about 3 million km 2.
The relief of the plain is monotonous, almost flat, and occasionally the height of the relief reaches 100 meters above sea level. In its western, southern and northern parts, the height can reach up to 300 meters. The subsidence of the territory occurs from south to north. In general, the tectonic structure of the West Siberian Plain is reflected in the terrain.
The main rivers flow through the plain - the Yenisei, Ob, Irtysh, and there are lakes and swamps. The climate is continental.
Geological structure of the West Siberian Plain
The location of the West Siberian Plain is confined to the epihercynian plate of the same name. The basement rocks are highly dislocated and date back to the Paleozoic period. They are covered with a layer of marine and continental Mesozoic-Cenozoic sediments (sandstones, clays, etc.) more than 1000 meters thick. In the depressions of the foundation this thickness reaches up to 3000-4000 meters. In the southern part of the plain, the youngest - alluvial-lacustrine deposits are observed, in the northern part there are more mature - glacial-marine deposits.
The tectonic structure of the West Siberian Plain includes a foundation and a cover.
The foundation of the slab has the appearance of a depression with steep sides on the east and northeast and gentle sides on the south and west. The foundation blocks belong to the pre-Paleozoic, Baikal, Caledonian and Hercynian times. The foundation is dissected by deep faults of different ages. The largest faults of submeridional strike are the East Trans-Ural and Omsk-Pur. The map of tectonic structures shows that the basement surface of the plate has an Outer Edge Belt and an Inner Region. The entire surface of the foundation is complicated by a system of rises and depressions.
The cover is interlayered with coastal-continental and marine sediments with a thickness of 3000-4000 meters in the south and 7000-8000 meters in the north.
Central Siberian Plateau
The Central Siberian Plateau is located in the north of Eurasia. It is located between the West Siberian Plain in the west, the Central Yakut Plain in the east, the North Siberian Lowland in the north, the Baikal region, Transbaikalia and the Eastern Sayan Mountains in the south.
The tectonic structure of the Central Siberian Plateau is confined to the Siberian Platform. The composition of its sedimentary rocks corresponds to the Paleozoic and Mesozoic periods. Characteristic rocks for it are sheet intrusions, which consist of traps and basalt covers.
The relief of the plateau consists of wide plateaus and ridges, at the same time there are valleys with steep slopes. The average height of the difference in the relief is 500-700 meters, but there are parts of the plateau where the absolute mark rises above 1000 meters, such areas include the Angara-Lena Plateau. One of the highest areas of the territory is the Putorana plateau, its height is 1701 meters above sea level.
Sredinny ridge
The main watershed ridge of Kamchatka is a mountain range consisting of systems of peaks and passes. The ridge extends from north to south and its length is 1200 km. In its northern part, a large number of passes are concentrated, the central part represents large distances between the peaks, in the south there is a strong dissection of the massif, and the asymmetry of the slopes characterizes the Sredinny Range. The tectonic structure is reflected in the relief. It consists of volcanoes, lava plateaus, mountain ranges, and glacier-covered peaks.
The ridge is complicated by lower-order structures, the most striking of which are the Malkinsky, Kozyrevsky, and Bystrinsky ridges.
The highest point belongs to and is 3621 meters. Some volcanoes, such as Khuvkhoytun, Alnai, Shishel, Ostraya Sopka, exceed 2500 meters.
Ural Mountains
The Ural Mountains are a mountain system that is located between the East European and West Siberian plains. Its length is more than 2000 km, its width varies from 40 to 150 km.
The tectonic structure of the Ural Mountains belongs to the ancient folded system. In the Paleozoic there was a geosyncline here and the sea splashed. Starting from the Paleozoic, the formation of the Ural mountain system took place. The main formation of folds occurred during the Hercynian period.
Intensive folding occurred on the eastern slope of the Urals, which was accompanied by deep faults and intrusions, the dimensions of which reached about 120 km in length and 60 km in width. The folds here are compressed, overturned, and complicated by thrusts.
On the western slope, folding occurred less intensively. The folds here are simple, without thrusts. There are no intrusions.
Pressure from the east was created by a tectonic structure - the Russian Platform, the foundation of which prevented the formation of folding. Gradually, folded mountains appeared in place of the Ural geosyncline.
In tectonic terms, the entire Urals is a complex complex of anticlinoriums and synclinoriums, separated by deep faults.
The relief of the Urals is asymmetrical from east to west. The eastern slope slopes steeply towards the West Siberian Plain. The gentle western slope smoothly transitions into the East European Plain. The asymmetry was caused by the activity of the tectonic structure of the West Siberian Plain.
Baltic shield
It belongs to the north-west of the East European Platform, is the largest protrusion of its foundation and is elevated above sea level. In the northwest, the border passes with the folded structures of Caledonia-Scandinavia. In the south and southeast, shield rocks are submerged under the cover of sedimentary rocks of the East European Plate.
Geographically, the shield is tied to the southeastern part of the Scandinavian Peninsula, to the Kola Peninsula and Karelia.
The structure of the shield involves three segments, different in age - South Scandinavian (western), Central and Kola-Karelian (eastern). The South Scandinavian sector is tied to the south of Sweden and Norway. The Murmansk block stands out in its composition.
The central sector is located in Finland and Sweden. It includes the Central Kola block and is located in the central part of the Kola Peninsula.
The Kola-Karelian sector is located in Russia. It belongs to the most ancient formation structures. In the structure of the Kola-Karelian sector, several tectonic elements are distinguished: Murmansk, Central Kola, White Sea, Karelian, they are separated from each other by deep faults.
Kola Peninsula
Tectonically tied to the northeastern part of the Baltic crystalline shield, composed of rocks of ancient origin - granites and gneisses.
The relief of the peninsula has adopted the features of a crystalline shield and reflects traces of faults and cracks. The appearance of the peninsula was influenced by glaciers, which smoothed the tops of the mountains.
Based on the nature of the relief, the peninsula is divided into western and eastern parts. The relief of the eastern part is not as complex as the western one. The mountains of the Kola Peninsula are shaped like pillars - at the tops of the mountains there are flat plateaus with steep slopes, and at the bottom there are lowlands. The plateaus are cut by deep valleys and gorges. In the western part there are the Lovozero tundra and the Khibiny Mountains, the tectonic structure of the latter belongs to the mountain ranges.
Khibiny
Geographically, the Khibiny belongs to the central part of the Kola Peninsula and is a large mountain range. The geological age of the massif exceeds 350 million years. Mountain Khibiny is a tectonic structure, which is an intrusive body (frozen magma) complex in structure and composition. From a geological point of view, an intrusion is not an erupted volcano. The massif continues to rise even now, the change per year is 1-2 cm. More than 500 types of minerals are found in the intrusive massif.
Not a single glacier has been discovered in the Khibiny Mountains, but traces of ancient ice are found. The peaks of the massif are plateau-shaped, the slopes are steep with a large number of snowfields, avalanches are active, and there are many mountain lakes. The Khibiny are relatively low mountains. The highest elevation above sea level belongs to Mount Yudychvumchorr and corresponds to 1200.6 m.
In the eastern part of the Urals, igneous rocks of various compositions are widespread among the Paleozoic sedimentary strata. This is associated with the exceptional wealth of the eastern slope of the Urals and Trans-Urals in a variety of ore minerals, precious and semi-precious stones.
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GEOLOGICAL URAL FOLDED REGION
The Ural folded region is an integral part of the Central Asian mobile belt, separating the East European, Siberian, Tarim and Sino-Korean ancient platform regions.
The folded structures of the Urals arose on the site of the Paleozoic Ural Ocean, which closed at the end of the Late Paleozoic as a result of the convergence of the East European, Siberian and Kazakhstan continental blocks.
The complexes that make up its modern structure lie in the form of a series of tectonic scales thrust onto the margin of the Russian Platform.
The eastern boundaries are hidden under the cover of the young West Siberian Plate. The Ural folded region is a typical example of linear collision structures of submeridian strike. There are external (western) zones that developed on the margin of the East European craton or near it, and internal (eastern) zones, where Paleozoic complexes of oceanic and island arc genesis are widely represented.
The boundary between the outer and inner zones is a strip of serpentinite melange marking the suture of the Main Ural Fault.
The external zones of the Urals include autochthonous complexes of the Cis-Ural foredeep and the Western and Central Ural folded zones.
1. The Cis-Ural marginal trough, filled with Permian continental molasse, is a structure bordering the East European Platform located along the western side of the entire structure of the Urals, except for Mugodzhar and Pai-Khoi. The width of this zone varies from 50 to 100 km.
Tectonics and geological structure of the Urals.
In the longitudinal direction, several depressions are distinguished in the structure of the trough: Belskaya, Ufimsko-Solikamskaya, Verkhne-Pechorskaya, Vorkutinskaya and others with a depth of up to 10-12 km. The pre-Upper Carboniferous deposits of the trough are similar to the coeval strata of the Russian Plate. The formation of the trough began in the Late Carboniferous, Early Permian and is associated with collision processes. Initially, it was a relatively deep-water basin, with deficient clayey-siliceous-carbonate sedimentation.
In the western part of the trough, biohermic limestones are developed, and in the east there are marine molasse deposits. In the Kungurian time, in the absence of connection with the ocean, evaporite strata formed in stagnant waters in the southern parts of the Urals, and coal-bearing ones in the more northern parts. Further deformations and the associated growth of the Urals led in the Late Permian and Early Triassic to intense erosion of folded structures and the gradual filling of the rear sedimentary basin with typically mollassic strata.
2. The Western Ural zone is represented in the modern erosional section by deformed Paleozoic sediments that formed under the conditions of the passive continental margin of the East European Platform. Paleozoic formations lie sharply unconformably on the rocks of an ancient folded basement, and are represented mainly by shallow sediments.
Tectonic nappes moved from more eastern zones, where oceanic and island-arc complexes were widely developed in the Paleozoic, are also common. The most typical deposits on the western slope of the Urals are shelf complexes. They are represented by rocks largely similar to those developed on the East European Platform.
The age of the base of the sedimentary cover naturally becomes younger from north to south. In Pai-Khoi and the Polar Urals, the section begins from the Cambrian - Early Ordovician. In the southern Urals, the base of the shelf section dates back to the upper Ordovician.
The composition of the bottom part of the section is formed by terrigenous sediments, which were formed due to the erosion of basement rocks of Eastern Europe. In some cases, bimodal volcanic complexes are noted at the base of the section, which is a clear indicator of continental rifting. The Silurian interval of the section is composed predominantly of graptolite shales.
Starting from the Upper Silurian, the section is dominated by limestones. The Lower Devonian is characterized by thick reef limestones up to 1500 m, which formed a barrier reef that was located along the margin of the East European continent. In the west, on the platform slope, organogenic limestones make up the entire section up to the end of the Carboniferous - Lower Permian. To the east, towards the then existing Ural Ocean, carbonate sediments are replaced by flysch.
At the collision stage, at the end of the Paleozoic, as a result of the powerful pressure of continental masses from the east (in modern coordinates), these complexes were dislocated and pushed on top of each other according to the “domino” principle, which was the reason for the modern duplexed structure of the Western Ural folded zone.
3. The Central Ural folded zone is an area of almost continuous outcrops of the Precambrian crystalline basement (pre-uralides). Ancient massifs represent the foundation of microcontinents that were torn away from the East European craton during rifting, or microcontinents that entered the modern structure of the Urals as a result of Late Precambrian collision processes.
The former are characterized by Riphean complexes that formed on the margins of the Early Precambrian East European continent. Typical representatives of this group are the Bashkir and Kvarkush massifs.
The most ancient formations here are AR-PR1 in age and are represented by gneisses, amphibolites and migmatites. Riphean-Vendian sedimentary strata lie above. The section is composed of a cyclic sequence of clastic and carbonate rocks, formed mainly in shallow water conditions due to the removal of clastic material from the continent.
At two levels in this section, volcanic rocks of trachybasaltic composition appear, probably associated with an episode of extension and the formation of a passive margin. The Riphean-Vendian complex is overlain by substantially carbonate deposits of the Silurian, Devonian, and Carboniferous, similar to the Western Ural zone.
The second group of pre-uralids includes folded complexes of the late Precambrian, represented by island-arc and sedimentary formations, which joined Europe in the Baikal time (at the end of the Precambrian).
The blocks composed of these complexes are most numerous in the Northern and Polar Urals within the Central Ural and Kharbey uplifts.
The cores of these antiform structures expose highly metamorphosed rock (gneiss-migmatite association). The peripheral parts are represented by transgressive volcanic-sedimentary deposits of the Late Riphean - Vendian and Lower Cambrian. The volcanic rocks are represented by zonally metamorphosed rocks of differentiated basalt-andesite-dacite calc-alkaline cal-sodium series, characteristic of island arc formations.
Metamorphosed volcanics are sharply unconformably overlain by Ordovician platform deposits. Glaucophane schists are often present in association with volcanics in the section, indicating an accretionary-collisional setting.
Similar traces of the collision and attachment of rock blocks to the East European continent can be seen in the Southern Urals within the Uraltau uplift.
The Main Ural Fault zone is a tectonic suture, expressed by a thick zone of serpentinite melange of variable width - from several to 20 km.
The fault itself is the frontal zone of the largest deep ridge, along which the simatic complexes of the eastern zones are thrust onto the sialic base of the western part of the Urals. The remains of this cover are blocks and plates of different sizes of various rock complexes that developed on oceanic-type crust, which are found in the outer zone of the Urals. Remains of the same rocks, including various members of the ophiolite association: hypermafic rocks, gabbros, pillow lavas, siliceous sediments, etc., are located among the flared serpentinite matrix within the band marking the thrust zone.
Often the fault is expressed by blastomilanites, metamorphic schists, including glaucophane, eclogites, i.e. rocks formed under high pressure. The development of eclogite-glaucophane metamorphism may indicate that most of these complexes arose in the frontal zones of island arcs under conditions of frequent collision (for example, island arc-microcontinent or seamount).
Thus, the formation of the main Ural fault zone is inextricably linked with accretion-collision processes
The internal zones of the Urals are most completely exposed in the Southern Urals and include the Tagil-Magnitogorsk, East Ural and Trans-Ural zones
1. The Tagil-Magnitogorsk zone includes a strip of troughs accompanying the zone of the Main Ural Fault from the east. From south to north, the West Mugodzharsky, Magnitogorsk, Tagil, and Voykar-Shchuchinsky synclinoriums become distinct.
In its structure, the zone is a synform structure, consisting of a series of tectonic nappes layered on top of each other. The structure of the nappes involves Ordovician-Carboniferous plutonic, volcanogenic and sedimentary rock complexes, which are considered as formations of oceanic basins, island arcs, marginal volcanic belts, associated deep-sea flysch troughs and shallow terrigenous and carbonate strata overlying the continental crust newly formed in the Paleozoic.
Protrusions of the Precambrian sialic basement are absent here. In general, the Tagil-Magnitogorsk zone can be represented as a field for the development of oceanic (ophiolitic) and island-arc (calc-alkaline) complexes that make up the well-known greenstone belt of the Urals. The formation of volcanic complexes of island arc genesis within the eastern part of the Urals occurred in several stages. Island arc volcanism began in the Middle Ordovician and continued into the Silurian.
Complexes of the corresponding age are noted within the Sakmara plate. Younger Early-Middle Devonian volcanics of the andesite-basaltic type form a strip along the eastern side of the Magnitogorsk cyclinorium (Irendyk arc). Middle-Late Devonian and Early Carboniferous subduction complexes are exposed within the Magnitogorsk belt.
2. The East Ural zone is a zone of development of Precambrian complexes of former microcontinents with allochthons composed of ophiolite association rocks and island arc complexes.
The pre-uralid complexes of the internal zones of the folded belt of the Urals make up uplifts, such as the Trans-Ural and East Ural, Mugodzharsky (the latter are sometimes combined into the Ural-Tobolsk anticlinorium or identified as the granite-metamorphic axis of the Urals).
They include predominantly Precambrian strata, as well as Lower Paleozoic formations, often of uncertain age, which, as a result of high-temperature metamorphism, sometimes become indistinguishable from Precambrian.
There is no consensus regarding the nature of pre-uralids in the East Ural zone.
Many researchers suggest that all of them are fragments of an ancient foundation that either belonged to other continents, or were torn away from Eastern Europe during the formation of the Paleo-Ural Ocean and joined the East European continent during the closure of the ocean in the late Paleozoic and, thus, included in the structure of the Urals on accretion-collision stage of its development.
With confidence, such a model can only be accepted for the Trans-Ural massif, within which there are remnants of the cover - Cambrian sediments and the Ordovician rift complex - an indicator of the split.
For the most part, structurally, the pre-uralids are granite-gneiss domes, with a characteristic two-tier structure. In the cores of the domes, forming the lower tier, AR-PR complexes predominate.
They underwent repeated metamorphism and metasomatic granite formation, as a result of which a polyphase metamorphic complex was formed: from the center of the dome there is a change from gneisses and migmatites to crystalline schists and closer to the edges to amphibolites with relics of granulite facies metamorphism. The upper tier of the domes is the so-called shale shell, which is not structurally consistent with the core and forms the periphery of the domes.
The composition of this shell is very diverse, among them there are ophiolites, sediments of the continental foot, shelf, riftogenic and other complexes that have undergone significant metamorphism.
The two-tier structure of the domes can be interpreted as a result of the fact that the rocks of the upper layer (oceanic and island-arc complexes of the Paleozoic) allochthonously overlap the Precambrian of the lower layer. The formation of the structure of the domes itself is most naturally associated with the diapiric ascent of the mobilized sialic base after the Paleozoic complexes were thrust onto the Precambrian base.
At the same time, both ancient and Paleozoic complexes were subjected to metamorphism. And the metamorphism itself was concentrically zonal in nature, decreasing towards the periphery of the domes. The time of formation of the domes corresponds to the time of the introduction of granite massifs and corresponds to the final stage of the formation of the folded structure of the Urals - at the Carboniferous - Permian boundary.
3. The Trans-Ural zone is the easternmost and most submerged area of distribution of paleozoids.
The predominant development in this zone is of Upper Devonian-Carboniferous volcanic-sedimentary deposits. A characteristic feature is the presence of volcano-plutonic complexes. This zone includes a band of calc-alkaline volcanics of the Lower-Middle Carboniferous, corresponding to the active continental margin of Kazakhstan (Valeryanovsky belt).
The belt is formed by andesites, basaltic andesites, dacites and diorites and granodiorites that cut through them. From the west, this belt is accompanied by ophiolites and island-arc complexes of the Silurian and Devonian, which can be considered as remnants of subduction melange formed in front of its front.
To the east of the belt, in its rear, carbonate and carbonate-terrigenous deposits of the Upper Devonian and Lower Carboniferous are developed, below which lie red rocks and volcanic rocks comparable to the deposits of Central Kazakhstan.
According to the above, the general structure of the Urals can be represented as formed from two structural complexes: lower autochthonous and upper allochthonous. The lower structural complex includes the foundation of the East European Platform, together with the sedimentary cover of the passive continental margin overlying it in the outer part of the Ural belt, as well as ancient Precambrian massifs that represent the foundation of microcontinents torn away from the East European craton during rifting, or microcontinents included in the modern structure of the Urals as a result of Late Precambrian collision processes.
The upper structural complex is formed by scales of oceanic and island-arc series thrust towards the East European Platform.
The folded structure of the Urals arose on the site of the former ocean due to the absorption of its crust. The Ural paleoocean was inherited from the Late Precambrian oceanic basin and developed at the site of the split of the margin of the East European continent.
Throughout the history of the Urals, three main tectonic stages can be distinguished:
1. The longest stage is associated with the formation and growth of the oceanic bed - from the Venian to the Devonian)
2. Intense subduction of oceanic crust in numerous subduction zones associated with island arcs - Devonian, Early Carboniferous
3. Collision associated with the collision of the East European, Siberian and Kazakhstan continents in the Late Carboniferous - Permian.
The formation of the folded structure of the Urals ended at the end of the Carboniferous or the beginning of the Permian. This is evidenced by the massive introduction of granite batholiths and the end of the formation of granite gneiss domes in the western part of the Urals. The age of most granite massifs is estimated at 290-250 million years. A deep trough was formed in front of the front of the Ural Mountains, into which erosion products arrived.
The further Mz-Kz history of the Urals consisted of its gradual destruction, peneplanation and the formation of weathering crusts.
Ministry of Education and Science of the Russian Federation
Federal Agency for Education
State Educational Institution of Higher Education
Vocational Education
Volgograd State Pedagogical University
Faculty of Natural Geography.
Coursework on physical geography of Russia
Subject: Ural Mountains
Completed by: EHF student
sleep geography
3rd year group G-411
Vodneva R.G.
Checked by: Klyushnikova N.
Volgograd 2006
Maintaining
The purpose of my course work: To explore the PTK - Ural, its geographical features and position on the territory of Russia.
This topic is relevant because:
- is connected with geography, therefore, it is necessary for a geography teacher, i.e.
in the school course 8th grade. natural complexes of Russia are studied.
Thus, this topic is very important to study in geography lessons. Therefore, I chose it as a necessary topic for my future profession, since I am going to work at school.
"STONE BELT OF THE RUSSIAN LAND"
“The Stone Belt of the Russian Land” is how the Ural Mountains were called in the old days.
Indeed, they seem to be girding Russia, separating the European part from the Asian part.
Mountain ranges stretching for more than 2,000 kilometers do not end at the shores of the Arctic Ocean. They only submerge in the water for a short time and then “surface” - first on the island of Vaygach. And then on the Novaya Zemlya archipelago. Thus, the Urals extends to the pole another 800 kilometers.
The “stone belt” of the Urals is relatively narrow: it does not exceed 200 kilometers, narrowing in places to 50 kilometers or less.
These are ancient mountains that arose several hundred million years ago, when fragments of the earth’s crust were welded together with a long, uneven “seam.” Since then, although the ridges have been renewed by upward movements, they have been increasingly destroyed. The highest point of the Urals, Mount Narodnaya, rises only 1895 meters. Peaks beyond 1000 meters are excluded even in the most elevated parts.
Very diverse in height, relief and landscapes, the Ural Mountains are usually divided into several parts.
The northernmost, wedged into the waters of the Arctic Ocean, is the Pai-Khoi ridge, the low (300-500 meters) ridges of which are partially submerged in glacial and marine sediments of the surrounding plains.
The Polar Urals are noticeably higher (up to 1300 meters or more).
Its relief contains traces of ancient glacial activity: narrow ridges with sharp peaks (karlings); Between them lie wide, deep valleys (troughs), including through ones.
Along one of them, the Polar Urals are crossed by a railway going to the city of Labytnangi (on the Ob). In the Subpolar Urals, which are very similar in appearance, the mountains reach their maximum heights.
In the Northern Urals, there are separate massifs of “stones” that noticeably rise above the surrounding low mountains - Denezhkin Kamen (1492 meters), Konzhakovsky Kamen (1569 meters).
Here the longitudinal ridges and the depressions separating them are clearly defined. The rivers are forced to follow them for a long time before they gain the strength to escape from the mountainous country through a narrow gorge.
The peaks, unlike the polar ones, are rounded or flat, decorated with steps - mountain terraces. Both the peaks and the slopes are covered with the collapse of large boulders; in some places, remnants in the form of truncated pyramids (locally called tumpas) rise above them.
The landscapes here are in many ways similar to those in Siberia.
Permafrost first appears as small patches, but spreads wider and wider towards the Arctic Circle. The peaks and slopes are covered with stone ruins (kurums).
In the north you can meet the inhabitants of the tundra - reindeer in the forests, bears, wolves, foxes, sables, stoats, lynxes, as well as ungulates (elk, deer, etc.).
Scientists are not always able to determine when people settled in a particular area.
The Urals are one such example. Traces of the activity of people who lived here 25-40 thousand years ago are preserved only in deep caves. Several ancient human sites have been found. Northern (“Basic”) was located 175 kilometers from the Arctic Circle.
The Middle Urals can be classified as mountains with a large degree of convention: in this place of the “belt” a noticeable failure has formed.
There are only a few isolated gentle hills no higher than 800 meters left. The plateaus of the Cis-Urals, belonging to the Russian Plain, freely “flow” across the main watershed and pass into the Trans-Urals plateau - already within Western Siberia.
Near the Southern Urals, which has a mountainous appearance, parallel ridges reach their maximum width.
The peaks rarely overcome the thousand-meter mark (the highest point is Mount Yamantau - 1640 meters); their outlines are soft, the slopes are gentle.
The mountains of the Southern Urals, largely composed of easily soluble rocks, have a karst form of relief - blind valleys, craters, caves and failures formed by the destruction of arches.
The nature of the Southern Urals differs sharply from the nature of the Northern Urals.
In summer, in the dry steppes of the Mugodzhary ridge, the earth warms up to 30-40`C. Even a weak wind raises whirlwinds of dust. The Ural River flows at the foot of the mountains along a long depression in the meridional direction. The valley of this river is almost treeless, the flow is calm, although there are also rapids.
In the Southern steppes you can find ground squirrels, shrews, snakes and lizards.
Rodents (hamsters, field mice) have spread to the plowed lands.
The landscapes of the Urals are diverse, because the chain crosses several natural zones - from the tundra to the steppes. Altitudinal zones are poorly expressed; Only the largest peaks, in their bareness, differ noticeably from the forested foothills.
Rather, you can perceive the difference between the slopes.
Ural Mountains (page 1 of 4)
Western, also “European”, are relatively warm and humid. They are inhabited by oaks, maples and other broad-leaved trees, which no longer penetrate the eastern slopes: Siberian and North Asian landscapes dominate here.
Nature seems to confirm man’s decision to draw the border between parts of the world along the Urals.
In the foothills and mountains of the Urals, the subsoil is full of untold riches: copper, iron, nickel, gold, diamonds, platinum, precious stones and semi-precious stones, coal and rock salt...
This is one of the few areas on the planet where mining began five thousand years ago and will continue to exist for a very long time.
GEOLOGICAL AND TECTONIC STRUCTURE OF THE URAL
The Ural Mountains were formed in the area of the Hercynian fold. They are separated from the Russian Platform by the Pre-Ural foredeep, filled with sedimentary strata of the Paleogene: clays, sands, gypsum, limestones.
The oldest rocks of the Urals - Archean and Proterozoic crystalline schists and quartzites - make up its watershed ridge.
To the west of it are folded sedimentary and metamorphic rocks of the Paleozoic: sandstones, shales, limestones and marbles.
In the eastern part of the Urals, igneous rocks of various compositions are widespread among the Paleozoic sedimentary strata.
This is associated with the exceptional wealth of the eastern slope of the Urals and Trans-Urals in a variety of ore minerals, precious and semi-precious stones.
CLIMATE OF THE URAL MOUNTAINS
The Urals lie in the depths. continent, located at a great distance from the Atlantic Ocean. This determines the continental nature of its climate. Climatic heterogeneity within the Urals is associated primarily with its large extent from north to south, from the shores of the Barents and Kara seas to the dry steppes of Kazakhstan.
As a result, the northern and southern regions of the Urals find themselves in different radiation and circulation conditions and fall into different climatic zones - subarctic (up to the polar slope) and temperate (the rest of the territory).
The mountain belt is narrow, the heights of the ridges are relatively small, so the Urals do not have their own special mountain climate. However, meridionally elongated mountains quite significantly influence circulation processes, playing the role of a barrier to the dominant westerly transport of air masses.
Therefore, although in the mountains the climates of the neighboring plains are repeated, but in a slightly modified form. In particular, at any crossing of the Urals in the mountains, the climate of more northern regions is observed than on the adjacent plains of the foothills, i.e.
e. climatic zones in the mountains are shifted to the south compared to the neighboring plains. Thus, within the Ural mountainous country, changes in climatic conditions are subject to the law of latitudinal zonation and are only somewhat complicated by altitudinal zonation.
There is a climate change here from tundra to steppe.
Being an obstacle to the movement of air masses from west to east, the Urals serves as an example of a physical-geographical country where the influence of orography on climate is quite clearly manifested. This impact is primarily manifested in better moisture on the western slope, which is the first to encounter cyclones, and the Cis-Urals. At all crossings of the Urals, the amount of precipitation on the western slopes is 150 - 200 mm more than on the eastern.
The greatest amount of precipitation (over 1000 mm) falls on the western slopes of the Polar, Subpolar and partially Northern Urals.
This is due to both the height of the mountains and their position on the main paths of Atlantic cyclones. To the south, the amount of precipitation gradually decreases to 600 - 700 mm, increasing again to 850 mm in the highest part of the Southern Urals. In the southern and southeastern parts of the Urals, as well as in the far north, the annual precipitation is less than 500 - 450 mm.
Maximum precipitation occurs during the warm period.
In winter, snow cover sets in in the Urals. Its thickness in the Cis-Ural region is 70 - 90 cm. In the mountains, the snow thickness increases with height, reaching 1.5 - 2 m on the western slopes of the Subpolar and Northern Urals. Snow is especially abundant in the upper part of the forest belt.
There is much less snow in the Trans-Urals. In the southern part of the Trans-Urals its thickness does not exceed 30 - 40 cm.
Subject: “Geological structure, relief and minerals of the Urals”Grade: 8
Goals:
educational:
L. Ya. Yakubovich
Writer Bazhov P.P. was originally from these places. Perhaps he knew everything about his native place. Loved the local legends. Here is one of them (Bashkir fairy tale ) about a giant who wore a belt with deep pockets. The giant hid his wealth in them. His belt was huge. One day the giant took it off, stretched it, and the belt lay across the entire earth, from the cold Kara Sea in the North to the sandy shores of the southern Caspian Sea. This is how the Ural ridge was formed. “Ural” in Bashkir means belt. Its length is 2500 km. It is difficult to point out a stone that has not been found in the Ural Mountains.
In the Central and Eastern parts of the Ural Mountains there are deposits of the famous Ural gems (precious and ornamental stones). In the Southern Urals in 1920. The world's first mineralogical reserve was created - Ilmensky.
Here are:
Malachite
Jasper
Chrysolite
Emerald
Rock Crystal and many, many other precious and ornamental stones.
Lesson summary, reflection: Let's remember the main points of the lesson
Ural - This is.....
These are low mountains
The mountains stretch from north to south
This is a folded area
Ural means “Stone”
The Urals used to be called the “belt”
This is a storehouse of minerals.
Homework: Write down in your notebook the Ural is...
The geological map of the Urals clearly shows the zoning of its structures. Over a vast area, rocks of different ages, compositions and origins stretch in meridional stripes. From west to east, six stripes are distinguished, replacing one another, and the western stripes can be traced throughout the entire length of the ridge, the eastern ones are observed only in the middle and southern regions of the Eastern slope, since in the northern regions the Paleozoic rocks are covered by Mesozoic, Paleogene and Neogene sediments of the West Siberian Lowland.
The formation of the first strip involves normal sedimentary Permian, Carboniferous and Devonian deposits, which can be traced throughout the Urals and uniformly replace each other from west to east. The part of the Western slope at the latitude of the Ufa Plateau stands out very sharply in terms of the nature of the rock arrangement. Here, the entire thickness of Carboniferous sediments, and in some places Devonian ones, often falls out of the section partially or completely; in such cases, Permian rocks are brought into direct contact with Lower Carboniferous, Devonian, and Silurian deposits.
The second strip morphologically makes up the axial part of the ridge and is composed of quartzites, crystalline schists, and generally highly metamorphosed Lower Paleozoic and Precambrian formations. Against the Ufa Plateau, the rocks of the second strip wedge out over a fairly significant extent.
The third strip belongs to the Eastern slope and consists entirely of altered volcanogenic accumulations, into which large bodies of gabbro-pyroxenite-dunite intrusions are embedded. They lie along the eastern border of the crystalline shales of the second band in the Northern and Middle Urals; in the Southern Urals there are numerous but small massifs of serpentines, sometimes with peridotites preserved among them. Petrographically, however, these formations are not identical to gabbro-peridotite-dunite intrusions. The Quaternary band lies within effusive rocks and tuffs of predominantly mafic magma from the Silurian to the Lower Carboniferous inclusive. Among them, sedimentary marine accumulations occur in sharply subordinate quantities. All these formations are highly dislocated and transformed into shales and greenstone strata.
The fifth band is represented by granite-gneiss massifs of Upper Paleozoic intrusions, overlain by Tertiary deposits in the eastern parts.
The sixth band is composed of highly metamorphosed, dislocated Middle and Upper Paleozoic formations, volcanogenic in the lower part and normal sedimentary in the upper part. They are cut through by intrusive rocks of various compositions. Outcrops along the Eastern slope of the Southern Urals show that the rocks of the sixth band are gradually plunging in the direction from west to east into the region of the modern West Siberian Lowland.
Large thrusts are developed along the boundaries of the strips.
A.D. Arkhangelsky at one time concluded that the first band is a monocline; the second, third and fifth bands structurally represent huge anticlinoria; the fourth and, possibly, the sixth have the appearance of large synclinal troughs.
Currently, such a tectonic structure of the Urals is proposed. To the east of the Pre-Ural foredeep there are: the Bashkir anticlinorium, the Zilair synclinorium, the Central Ural anticlinorium, the Magnitogorsk synclinorium and the Nizhny Tagil synclinorium, which continues to the north, an anticlinal zone of granite intrusions, the East Ural synclinorium, and the Trans-Ural anticlinorium. To the east, the folded structures of the Urals are submerged under the Mesozoic and Cenozoic deposits of the West Siberian Lowland.
The general strike of the structures of the Urals is meridional or close to it. The Bashkir anticlinorium is composed of Lower Paleozoic rocks; the Silurian and Lower Devonian are absent. Despite the high age of the rocks, they are characterized by weak metamorphism. The strike of folds in the southern parts is almost meridional, in the northern parts it deviates to the east. Here the direction of the folds depends on the configuration of the eastern edge of the Russian Platform.
Between the Bashkir and Central Ural anticlinorium lies the Zilair synclinorium. In the south of the Western Urals, it bypasses the Bashkir anticlinorium and becomes the western outskirts of the Urals there. Similarly in the north around 51° N. w. The Zilair synclinorium closes and there the Central Ural anticlinorium becomes the marginal zone of the Urals. The Zilair synclinorium is composed of rocks from the Lower Paleozoic to Tournaisian inclusive. The difference in stress and eroded folding of the lower complex and the calm upper complex, starting from the Upper Devonian deposits, is clearly visible.
The sharp tectonic difference between the Western and Eastern Urals was outlined by F.N. Chernyshev and A.P. Karpinsky.
The type of cover structures actually exists, probably, only at the latitude of the Ufa Plateau. Geological study of the Urals, carried out by E. A. Kuznetsov, in the transverse direction along well-exposed areas along the river. Chusovoy, from the west from Kuzino station to Bilimbai, revealed the phenomena of large thrust structures here.
Throughout the Urals, a huge structure can be traced - the Central Ural Anticlinorium, which from the Middle Urals to the Polar inclusive is a marginal folded zone. The anticlinorium is composed of sedimentary, igneous and metamorphic Precambrian and Lower Paleozoic rocks. In the western part, on their eroded intense folds, younger strata up to the Permian lie unconformably.
The Magnitogorsk and Nizhny Tagil synclinoriums already belong to the Eastern slope of the Urals and they were built mainly by Middle Paleozoic, especially volcanogenic accumulations, which underwent greenstone degeneration due to dislocation. Three volcanic cycles have been established: 1) Silurian-Lower Devonian; 2) Middle Devonian - Upper Devonian; 3) Lower Carboniferous.
To the east, only in the southern part of the Urals, there is an anticlinal zone of granite intrusions (from 59° N to Mugodzharami). This is a zone of huge granitoid massifs, such as Saldinsky, Murzinsky, Verkh-Isetsky, Chelyabinsky, Troitsky, Dzhebyk-Karagaysky. Basic and ultrabasic rocks are of subordinate importance here. It is now believed that highly dislocated Lower Paleozoic and pre-Paleozoic rocks are widespread within this structure.
North from 58° to 51° N. w. there is the East Ural synclinorium with predominant Middle Paleozoic formations in the presence of Middle Carboniferous, possibly younger, and Upper Triassic coal accumulations of the Chelyabinsk type. The folds are overturned to the east. There are many intrusive deposits. The Trans-Ural anticlinorium in the Southern Urals is an eastern regional structure formed by ancient rocks. The relationships between the northern parts of the Urals and the folded regions of Pai-Khoi and Vaygach - Novaya Zemlya have not yet been clarified. They indicate that north of Konstantinov Kamen along the western shore of the lake. The Bolshoi Osovey thrust stretches almost to the shore of the Kara Sea. The spilites and diabases lying along it at the base of the Silurian are in contact with the Upper Paleozoic rocks of Pai-Khoi. There is information about a close structural and facies connection between Pai-Khoi and Vaygach, Novaya Zemlya and the Pechora basin. It is also assumed that the northern part of the Taimyr Peninsula and the island are a direct continuation of the folded strip of the Northern Urals to the east. Northern Land. The geological profile along the Bisert - Bogdanovich line at the latitude of the Ufa plateau can well show the importance of the latter in the formation of the structures of the Urals. Here the strata of both slopes are greatly reduced. The western zone is characterized by imbricate folding with sharp, steep thrust faults, especially between the Paleozoic and metamorphic formations. The northwest shift narrowed the greenstone belt to a negligible size. As in the previous profile, between the greenstone strip and Sverdlovsk there is a large Verkh-Isetsky massif. The main breeds were the first to be intruded here; in their wake, plagiogranites and granites of normal composition were intruded.
To characterize the tectonics of the Southern Urals, we will use the data of A. A. Bogdanov. On the Western slope, he identifies the following main structural elements: the Ural-Tau and Bashkir anticlinorium, separated by the Zilair synclinorium, the southern part of which is complicated by the Sakmara anticlinorium; zone of blocky disturbances framing the Bashkir anticlinorium; a series of linear folds of the Orenburg-Aktobe Cis-Urals, located on the Sakmara flexure; a zone of complex folded structures of the Eastern slope of the Urals, adjacent to the Ural-Tau anticlinorium from the east.
The schematic sections constructed by A. A. Bogdanov clearly show two structural tiers. The lower one consists of complex folded pre-Devonian strata and represents geosynclinal Caledonides; the upper one is built by Devonian, Carboniferous and Permian rocks, unconformably overlying the Caledonides; here the rocks are collected in calm gentle folds, and in the west, in the region of the Russian Platform, they take on a horizontal bedding. A similar two-tier structure can be traced throughout the Western slope of the Urals, representing, therefore, a Caledonian structure, unconformably overlain by Hercynian structures of a post-geosynclinal nature.
The eastern slope along its entire length is a typical eugeosynclinal structure of Hercynian tectogenesis, broken by faults into horsts and grabens. In the latter, Mesozoic and Cenozoic continental accumulations lie on the eroded surface of the Hercynides, creating a second structural layer of weakly disturbed strata.
To the east of Zlatoust there are: 1) the western greenstone zone, stretching to the west of the city of Miass; 2) the central zone of carboniferous serpentines, granites and siliceous shales - from Miass to st. Poletayevo and 3) the eastern zone of greenstones and granites - from the station. Poletayevo to Chelyabinsk.
Within the western greenstone belt on the Eastern slope of the Southern Urals, folds are developed, overturned and thrust westward onto the Precambrian crystalline schists in the vicinity of Zlatoust. In the cores of the folds there are serpentines ettruded with gabbro and diorite. The most ancient rocks of the folds are Silurian and Lower Devonian diabases and pyroxenite porphyrites, accompanied by tuffs, siliceous shales and jaspers. Above them, they are replaced by Middle Devonian effusive albitophyres, quartz-plagioclase and pyroxene porphyrites and conglomerates with pebbles of previous gabbros and diorites. Even higher in the section there is a thick Upper Devonian sequence of siliceous shales overlain by greywackes. They are covered by Visean limestones. The central zone of the coils is intensively dislocated throughout its entire length; it contains preserved bands of pyroxene porphyrites and their tuffs of Devonian age. The Hercynian granite-gneiss massif of the Ilmen Mountains belongs to this zone, with which miaskites - alkaline granites - are associated.
The eastern greenstone zone makes up wide areas to the west of Chelyabinsk. Diabases, pyroxene-plagioclase porphyrites, tuffs, tuffites with subordinate siliceous shales and red jaspers are intensively dislocated here. These rocks in the period from the Silurian to the Middle Devonian were intruded by gabbro, later by granodiorites and granites. The latter are cataclased and transformed into granite gneisses. Hydrothermal solutions were associated with the emplacement of granitic magma, causing the formation of arsenic, tungsten and gold deposits.
Various geological and geophysical studies carried out in recent years on the territory of the Southern Urals and the adjacent eastern margin of the Russian Platform have shed new light on the structure of the deep regions of the earth's crust. It turned out to be possible to distinguish two zones within the Ural folded region: external and internal.
The outer one occupies most of the western slope of the Southern and Middle Urals and is characterized by the same magnetic and gravitational anomalies as those found on the adjacent parts of the Russian Platform and in the Cis-Ural foredeep.
The internal zone covers the entire slope of the Urals with its magnetic and gravitational properties, reflecting the features of the deep structure.
Magnetic and gravitational anomalies in the outer zone can be interpreted in the sense that the crystalline basement in the area of the western slope of the Urals plunges sharply to 11-16 km instead of 4-6 km under the Russian platform. Seismic data revealed less subsidence of the basalt and peridotite “layers” on the same Western Slope. This contradiction is explained by a decrease to 7-10 km in the thickness of the granite “layer” within the Western slope and the Cis-Ural trough.
The transition from the outer to the inner zone, as indicated by F.I. Khatyanov (1963), is expressed by a strip of high gradients of averaged gravity anomalies. It seems to separate the West Ural gravitational minimum from the East Ural maximum. Here the basalt “layer” rises by 6-10 km, and the granite one becomes significantly thinner, so that it approaches the oceanic type. In this strip it is possible to expect a deep fault, which is the eastern boundary of the crystalline substrate of the Russian Platform, which, therefore, lies at the base of the Western slope of the Urals (outer zone). F.I. Khatyanov suggests that, due to this structure of the Western slope, it is structurally closer to the platform. He even suggests a name - folded platform zone. The Eastern Urals with its powerful magmatism, intense folding and strong metamorphism are a true geosyncline.
Cycles and phases of tectogenesis. The structure of the Urals took shape over an extremely long period of time under the influence of the Salairian, Caledonian, Hercynian, Cimmerian and Alpine cycles of tectogenesis. The most important were the Paleozoic cycles, which created the huge complex folded Ural structure; Mesozoic and Cenozoic cycles manifested themselves in the form of faults and multiple block movements; they did not change the main folded structure and formed only the external geomorphological appearance of the Urals. The sharp difference in the degree of metamorphism of the Lower Paleozoic strata and the underlying crystalline schists and quartzites indicates the existence of isolated fields of Precambrian rocks in different parts of the Urals. The gradual transition of these rocks to the rocks of the Lower Paleozoic is now denied by most researchers.
Salair tectogenesis is most reliably established for the Beloretsk plant area, where the Ordovician lies at the base on quartzites, shales and limestones with algae and, possibly, Middle Cambrian archaeocyaths, unconformably with the basal conglomerate. The fallout of the Upper Cambrian was also observed in the river basin. Sakmara. Its absence, according to D.V. Nalivkin, is a widespread phenomenon: the Upper Cambrian falls out of the section in the Baltic states, on Novaya Zemlya, in the Urals, in the Tien Shan, in the Kazakh steppe, in Altai, in the Kuznetsk basin, in a number of places in the Siberian platforms. This is the result of the Salair folding, which some geologists attach to the Caledonian cycle. Caledonian tectogenesis manifested itself throughout the Western Urals region; it has also been proven for Mugojar. It was accompanied not only by the formation of folds, but also by the introduction of magma: the granites of the Troitsk deposit on the Western slope of the Middle Urals and in the south of Mugodzhar, in the Southern Urals are considered Caledonian. Starting from Mugodzhary to the northernmost tips of the Urals, conglomerates and sandstones of the Middle and Upper Devonian usually contain fragments and pebbles of a variety of Lower Paleozoic and Precambrian sedimentary and. This shows that the Devonian sea transgressed onto a relief surface developed during the folded Lower Paleozoic, the structures of which included Caledonian granites and Precambrian rocks. For Mugojar and Timan, it is well established that Caledonian tectogenesis was manifested by folding, magma intrusions and uplifts with the emergence of land on which relief began to develop. In some areas of the Southern and Northern Urals, Caledonian tectogenesis is judged by the overlapping of the continental Lower Devonian on the marine Upper Silurian; in places the Lower Devonian is completely absent.
Hercynian tectogenesis has been established in the Urals for the longest time. This cycle was expressed with great force and intensity on the Eastern slope of the Urals; in the West, it manifested itself with moderate intensity, often even faintly over large areas.
The complete stratigraphic section from the Upper Devonian to the Lower Carboniferous in the Urals indicates the absence of the Breton phase. On the Western slope, a fauna of the Etrenian type is observed, representing a mixture of Devonian and Carboniferous forms.
The Sudeten phase on the Eastern slope of the Urals can be judged by the sharp change in lithological composition at the base of the Middle Carboniferous, where thick coarse conglomerates and sandstones are established; D.V. Nalivkin rightly notes that this change indicates an uplift that began then not within the Eastern slope of the Urals, but somewhere to the east of it; the mountainous country here rose and, entering the conditions of the denudation regime, quickly collapsed; the products of destruction were conglomerates and sandstones deposited on the Eastern slope of the Urals. On the Western Slope, the Lower Carboniferous limestones usually gradually change into the Middle Carboniferous limestones, the latter passing into the Upper Carboniferous without interruption or unconformity; this indicates the absence of manifestations of the Sudeten and Asturian phases here.
The Asturian phase appeared on the Eastern slope of the Urals, where Upper Carboniferous sediments completely fall out of the section due to uplifts that covered the territory of the Eastern slope by the beginning of the Upper Carboniferous. Since then, the region of the Eastern slope of the Urals has become a place of intense tectonic movements that have created extremely complex structures. From the beginning of the Permian period, the eastern and central zones (strips) of the Urals turned into a powerful mountain range; simultaneously with the processes of formation, it immediately began to collapse, producing a huge amount of clastic material, which was carried to the territory of the Western slope, where the marine regime continued to be maintained in the resulting trough; This is why it is so difficult to draw a boundary between the Carboniferous and Permian.
Cimmerian tectogenesis was expressed by the dislocation of Mesozoic coal-bearing deposits in the Chelyabinsk region. Based on the remains of the flora, it was possible to determine that a significant part of these deposits belongs to the Upper Triassic; folds of the coal-bearing strata are unconformably overlain by undisturbed Upper Cretaceous and Paleogene accumulations. When studying the morphological structure of the Chelyabinsk basin, microfolds are found in it - flattened, overturned, pointed beak-shaped; they give the structure a wrinkled character; the greatest dislocation is observed at the sides, where Mesozoic layers are adjacent to Paleozoic massifs; With distance from the sides of the massifs, folding fades. Mesozoic deposits, as mentioned earlier, are concentrated in deep grabens among massifs of Paleozoic rocks.
The nature of the Cimmerian structures shows that the Cimmerian folding that gave rise to them is passive, resulting from the collapse of loose Mesozoic sediments by Paleozoic blocks into small overturned, isoclinal, and sometimes broken folds. The likelihood of such an explanation is also confirmed by the locality of Mesozoic folding.
In the Chelyabinsk basin, it is the result of landslides of Mesozoic age, simultaneous with the deposition of sediments and occurring along the banks or at the bottom of the corresponding water basins. Alpine tectogenesis in the Urals was manifested by block movements of Paleozoic massifs. Occasionally occurring local folds in the Chelyabinsk and Lozvinsky regions are caused precisely by these movements. They also created the following, now observable, geomorphological features of the Urals: the storey arrangement of leveling surfaces; redevelopment of a parallel-linear river network into an articulated-composite one; formation of two watersheds; the sharp difference between ancient and modern river systems; hanging valleys; high terraces on Akchagyl sandy-clayey deposits; rejuvenation of river valleys. Due to young faults, the Neogene rocks of the Urals lie at different heights, and weak earthquakes occur in the north of the Ufa Plateau, noted by the Sverdlovsk Geophysical Observatory.
Relief formation. The study of ancient platforms has revealed the remarkable stability of tectonic structures. Most of them, being founded at the end of the Precambrian - the beginning of the Paleozoic, still exist, changing only in their outlines and sizes. Large geomorphological elements, which are usually tectonomorphic, also have the same stability. At the same time, the modern tectonic structure and modern relief of both platforms were formed by neotectonic movements that began in the Neogene. They manifested themselves mainly radially in uplifts and subsidences, which was previously called epirogenesis. However, the presence of folded, tangential formations with a large radius of curvature began to be discovered more and more often.
Turning now to the study of the large Ural fold system of the Paleozoic, we find the same characteristic tectonic and geomorphological features, expressed even more clearly. Manifestations of neotectogenesis are observed especially with great efficiency in the post-Precambrian folded areas. It is to him that these areas owe their revival after the peneplainization of the mountainous terrain. However, in different folded areas the degree of mobility turned out to be different, and therefore the restored (regenerated) mountains are divided into: a) weakly mobile - the Ural type; b) mountains of the Tyanypan-Baikal type with very high mobility, restored on the site of the Epido-Cambrian, Epicaledonian, Epi-Hercynian platforms; c) mountains of the Verkhoyansk-Kolyma type, also of significant mobility, but rising on the site of Mesozoic folding; d) mountains of the Caucasian-Pamir type in the belt of Mesozoic-Cenozoic orogenesis. In all these types, with very different hypsometry, the structural and geomorphological features turn out to be common.
Neotectogenesis inherited all the main structures created in geosynclinal stages, their regional revitalization of faults, including deep faults, which bounded the blocks, making them distinct in modern times.
The structures of the Urals, developed on the site of the Caledonian and Hercynian geosynclinal furrows, after orogenesis were also orographic elements: ridges were associated with anticlinoria, depressions - synclinoria, sharp changes in relief - ledges - to the lines of large faults. In Mesozoic times, these structures and tectonomorphic relief experienced peneplanation, and the synclinal depressions were filled with proluvial, alluvial and lacustrine sediments, the material for which was the destruction products of neighboring uplifts. The very significant power of these accumulations indicates that structures continue to develop posthumously, already in a platform environment. By the end of the Mesozoic, denudation reduced the Urals to an almost plain with a well-developed topography and wide valleys oriented meridionally, that is, along the strike of the main structures. But in the Neogene, neotectonic movements of a differentiated nature appeared with uplifts and subsidences of significant amplitude. The inherited Mesozoic relief with a longitudinal hydrographic network began to be reconstructed; the relief received a general rejuvenation. The longitudinal parallel-linear river network turned into an articulated-composite one, since new valleys were obtained from the connection of two or more independent ones through the formation of transverse, epigenic elbows. Tectonic fractures played a noticeable role in this. But, despite these rearrangements of the relief, its tectonomorphism and inheritance have been preserved to the present day, which is so clearly expressed in the meridional strike of the ridges, subordinate to the strike of the structures.
Along with clearly expressed blocky vertical movements, observations more and more reliably indicate wave arched uplifts, that is, large-radius folding of the dislocated base.
The magnitude of the rise of the Ural Mountains under the influence of neotectogenesis, in other words, since the Neogene, can be judged approximately: for the Southern Urals, rises of 700-800 m are allowed, for the Middle (Chusovaya River basin) - 200-300 m, for the Northern - 500-800 m It is remarkable that positive structures (anticlinorium, horsts) rise more than negative ones (synclinorium, grabens).
To the south, the Ural Paleozoic structures plunge, appearing on the surface as the Chushkakul uplift.
In general, neotectonic movements in the Urals are not large, which determined its mid-mountain relief and weak seismicity, confined to the Middle Urals and not exceeding 6 points in strength. For the earthquake of August 17, 1914, a map of isoseisms was compiled, which give a northwest-southeast orientation at an angle to the meridional strike of the structures.
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The Urals on Earth is a unique phenomenon.
- And in its role as a planetary suture that once held two great continents together.
- And because of the abundance of natural landscapes here, scattered generously throughout its entire space.
- And in terms of climatic diversity.
In fact, where else will you find such a region, where the head would be cooled by the centuries-old ice of the Northern Ocean, and the foot would be scorched by the calcined sands of the deserts? A land where, on the same June day, the never-setting sun shines over the blooming polar tundra and the herbs of alpine meadows luxuriously spread out. Where you can hunt to your heart's content in the cedar trees or, after admiring the harmonious choirs of elegant birch tufts, stop at a Bashkir nomad camp, drink plenty of chilled kumiss, while watching how everything around vibrates in the sultry steppe haze...
And now from these poetic pictures of the Ural region we will have to move on to more prosaic, but very necessary for our story, things. It is not without interest, I think, to understand for ourselves how such an unusual natural creation appeared on the body of the planet, what forces erected it. Therefore, a short excursion into the science that studies the Earth is inevitable - into geology.
What does modern geology define by the concept of “Ural”?
Strictly speaking, the Urals are a mountainous country with areas of two great plains adjacent to it from the west and east. Why geologists think so will be discussed 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, and it stretches from the Aral deserts to the Arctic Ocean for more than two and a half thousand kilometers. In this way, it is similar to 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, or something, than their famous counterparts somewhere in the Alps or Himalayas.
But if the Ural Mountains are not striking in appearance, then the content of their subsoil 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 we must understand the significance of this fact to the subtlest shade - the Urals are perhaps 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, at different times) of all conceivable physical and chemical regimes both in the interior of the Earth and on its surface. Some kind of utter mishmash of geological creations of different ages and different characteristics!
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. Bauxite and corundum. And... and... and... The list is endless - not everything has been discovered yet, and we still don’t know all types of minerals.
