The ancient name of the West Siberian Plain. Geological structure and relief
The West Siberian Lowland is a single physical-geographical region consisting of two flat bowl-shaped depressions, between which lie latitudinally elongated elevations (up to 175-200 m), united orographically into the Siberian ridges.
The lowland is delineated by natural boundaries on almost all sides. In the west it is clearly delimited by the eastern slopes of the Ural Mountains, in the north by the Kara Sea, in the east by the valley of the Yenisei River and the cliffs of the Central Siberian Plateau. Only in the south is the natural boundary less pronounced. Gradually rising, the plain here passes into the adjacent hills of the Turgai plateau and the Kazakh hillocks.
The West Siberian Lowland occupies about 2.25 million km 2 and has a length from north to south of 2500 km, and from east to west (in the southern widest part) 1500 km. The exceptionally flat relief of this territory is explained by the leveling of the complex folded foundation of the West Siberian Platform with a thick cover of Meso-Cenozoic sediments. During the Holocene, the territory experienced repeated subsidence and was an area of accumulation of loose alluvial, lacustrine, and in the north - glacial and marine sediments, the thickness of which in the northern and central regions reaches 200-250 m. However, in the south the thickness of Quaternary sediments drops to 5-10 m and the modern relief clearly shows signs of the impact of neotectonic movements.
The peculiarity of the paleogeographical situation lies in the strong watering of the territory inherited from the Holocene and the presence at present of a huge number of residual reservoirs.
Large modern landforms of Western Siberia represent morphostructures created by the latest movements earth's crust. Positive morphostructures: hills, plateaus, ridges - have a more dissected topography and better drainage. Negative morphostructures are dominant for the relief of the territory - plains covered with a thickness of loose layered sediments, often gleyed to great depths. These properties impair the water permeability of the strata and inhibit groundwater flow.
The flatness of the territory determined the special nature of the hydrographic network: low water flow rates and significant tortuosity of the riverbeds. The rivers of Western Siberia have a mixed supply - snow, rain, ground, with a predominance of the first. All rivers are characterized by long spring floods, often turning into summer ones, which is explained by at different times opening up rivers in various parts of the catchment areas. Flood waters, spreading over many kilometers, are an important factor in the extremely high water supply of watersheds, and rivers practically do not play their drainage role during this period.
Thus, the combination of physical and geographical factors that favorably influence the swamp formation process determined the intensity of the formation and accumulation of huge reserves of peat and the widespread distribution of peat deposits throughout the West Siberian Plain.
The vegetation cover of peat deposits in the West Siberian Lowland has not been studied in sufficient detail. The tree layer of forested peatlands here is much richer in species composition due to species characteristic of the taiga forests of Siberia, such as cedar, fir, and larch. Usually they, together with birch, spruce, and pine, make up the forest of swamps in various combinations and quantities. Almost pure stands of birch on peat bogs are quite common and, under appropriate conditions, are found in all peat-bog areas of the West Siberian Lowland. Pure thickets of willow are noted on the lowland peat bogs of the floodplains.
In the shrub layer of the vegetation cover of Western Siberian swamps, such a representative of the Siberian flora as Salix sibirica is found, but the European species Calluna vulgaris is not reflected in it. Representatives of the Siberian flora were also noted in the herbaceous layer: Carex wiluica, Cacalia hastata, Ligularia sibirica. Carex globularis, found in the European part of the Union as part of the vegetation of swampy spruce forests, has expanded its habitat in Western Siberia and is found in large numbers on typical high-moor peat bogs. Sph. rubellum and Sph. cuspi datum - typical inhabitants of high peat bogs in the northwestern region of the European part of the Union - are rarely found in the moss cover of peat bogs of the West Siberian Lowland. But in much greater quantities and in more southern latitudes, Sph are distributed here in the moss cover of swamps. lindbergii and Sph. congstroemii, which are typical for peat bogs of the Arkhangelsk region and are rare in peat bogs middle zone. Sometimes, in the ridge-lake areas of the Vasyugan watershed peatlands, Cladonia and Cetraria form continuous patches, and up to 12 species of Cladonia are found in this regenerative complex.
Of the plant phytocenoses of the West Siberian Lowland, it is necessary to note the grass-sedge plant, which covers significant areas in the edge areas of the fields (in conditions of some soil salinity). It includes reed grass (Scolochloa festucacea), reed grass (Calamagrostis neglecta), Carex omskiana, C. appropinquata and C. orthostachys. For peat bogs, birch (up to 15-20 m high) and conifers: spruce, cedar, pine, larch, in the undergrowth along with willows (Salix sibirica, S. pentandra) black currant, rowan, bird cherry; in the shrub layer - bog myrtle, lingonberry, blueberry, cloudberry. The grass stand is rich in species and develops luxuriantly; it is dominated by C. caespitosa, other sedges include C. globularis, C. disperma, and taiga plants (Equisetum silvaticum, Cacalia hastata, Pyrola rolundifolia) also grow in the forbs along with marsh plants. Elements of taiga flora are also observed in the moss cover: on hummocks Sph. warnstorfii - Pleuroziumschreberi and Hylocomium splendens, in inter-tussock depressions - Thuidium recognitum, Helodium blandowii, on the slopes of hummocks - Climacium dendroides. In the depressions between hummocks in Sogras one can often observe efflorescence of iron.
Most often, sogras cover the edge areas of low-lying marshy swamps of terraces above the floodplain along the channels of the Ob, Irtysh, Chulym, Keti, and Tym rivers. From the outside they gradually turn into swampy forests, towards the center of the peat bog - into a forest complex phytocenosis.
In the West Siberian Plain, borrowings predominate in the Ishim peat-bog region between the Ishim and Tobol rivers in their middle reaches. Here they adjoin the lakes or surround them in a continuous ring. Huge areas are sometimes occupied by land in lowlands that are no longer connected with lakes, but bear the features of former channels between lakes.
Zaimishchno-ryam peatlands are often found in the eastern part of the South Barabinsk peat-bog region, where they are confined to lakes or flat depressions in which surface water stagnates for a long time. Scattered among the borrowings are raised convex peat bogs, which occupy, in comparison with the borrowings, small area. These are the well-known “ryams”. During the growing season, a variable water-mineral regime is created in the fields: in the spring and in the first half of summer they are flooded with fresh deluvial melt water, and often with river hollow water; in the second half of the growing season, loans dry up in a larger peripheral area, and favorable conditions for capillary rise of saline soil-groundwater to the surface and efflorescence of salts (Ca, Cl and SO 3) is usually observed on the surface.
The area of the borrowing area can be divided into: a zone of constant moisture with relatively fresh waters (the central part of the borrowing area, the banks of lakes and river channels) and a zone of variable moisture, where both the degree of water content and the degree of mineralization of the feeding waters are variable (peripheral parts of the borrowings).
The central parts of the fields are covered with reed phytocenosis, in which the main background plants are reed, reed (Scolochloa festucacea), reed grass, sedge (C. caespitosa and C. wiluica). The phytocenosis includes Carex omskiana, C. buxbaumii, watchwort, and bedstraw (Galium uliginosum) as admixtures. Among the components of the reed phytocenosis, reed, reed grass, Carex caespitosa and C. buxbaumii are salt-tolerant plants.
In the zone of borrowings where constant moisture begins to give way to variable moisture, under conditions of some salinization of the substrate, a gradual thinning of reed thickets and the introduction of sedges (C. diandra, C. pseudocyperus), cattail and reed grass are observed. The sedge-reed phytocenosis is characterized by isolated scattered bushes of birch (B. pubescens) and willow (S. cinerea).
Along the periphery of the fields in the zone of variable moisture, reed grass (Scolochloa, festucacea), which in the conditions of Baraba is an indicator of mixed chloride-sulfate salinity, displaces reed grass from the plant cover, and here a grass-sedge phytocenosis arises mainly from reed grass, Carex omskiana, C. appropinquata and C. orthostachys with a small participation of the same reed grass.
The formation and development of ryams (oligotrophic pine-shrub-sphagnum islands) occurs in isolation from saline soils in both horizontal and vertical directions. Insulation in the horizontal direction is a deposit of loans; insulation in the vertical direction is a layer of reed peat with an average degree of decomposition of 22-23%, underlying the upper ryam deposit. The thickness of the reed peat is 0.5-1.5 m, the thickness of the upper deposit is 0.5-1 m. The upper deposit is composed of weakly decomposed fuscum peat with a degree of decomposition of 5-20%. The stump content of the sphagnum deposit is low and falls from upper layers to the lower ones.
The surface of the ryam is sharply convex with asymmetrical slopes. Under the tree layer of pine, a shrub layer and a moss cover of Sph are developed. fuscum with impurities Sph. angustifolium and Sph. magellanicum.
The largest ryams up to 1000-1500 hectares (Bolshoy Ubinsky and Nuskovsky) are found in the northern and middle parts of the forest-steppe zone. Usually the area of ryams is 100-400 hectares, sometimes 4-5 hectares (small ryams of the Chulym region).
Peat deposits in Western Siberia are extremely diverse in terms of the conditions of formation and development, qualitative and quantitative indicators of the deposit, vegetation cover, distribution patterns and other factors, the changes of which can be traced to a fairly clear pattern, closely related to natural latitudinal zoning. According to this principle, 15 peat-bog areas have been identified in Western Siberia.
The far north of the West Siberian Lowland occupies area of arctic mineral sedge bogs. It geographically corresponds to the West Siberian subzone of the Arctic tundra. The total swampiness of this territory is almost 50%, which is a consequence of the waterproof frozen layer located close to the surface, the excess of precipitation over evaporation and the flatness of the country. The thickness of the peat layer does not exceed several centimeters. Peatlands with deep deposits should be classified as relics of the Holocene climatic optimum. Polygonal and flat moss-sedge bogs are common here.
The wide distribution of eutrophic moss-sedge bogs with a flat surface (up to 20-25% of the total area) is noteworthy. Carex stans or Eriophorum angustifolium dominate here, with a moss carpet of Calliergon sarmentosum and Drepanocladus revolvens.
In river valleys among sedge bogs there are mounds covered with Sph. warnstorfii, Sph. lenense, Dicranum elongatum and lichens. Flowering plants include abundant thickets of Betula nana and Rubus chamaemorus.
Along the shores of bays and the Kara Sea there are coastal swamps that are flooded during surge winds sea water. These are largely brackish marshes with grasses (Dupontia fisonera), sedges (Carex rariflora, etc.) and Stellaria humifusa.
Mossy tundras are especially characterized by the abundance of Eriophorum angustifolium on the moss cover of Aulacomnium turgidium, Camptothecium trichoides, Aulacomnium proliferum, Dicranum elongatum, and Ptilium ciliare. Sometimes the swampy tundra is dominated by sedges (Carex stans, Carex rotundata) with a similar composition of the moss cover and the participation of sphagnum mosses.
Located further south area of flat-hilly bogs. This zone geographically corresponds to the tundra. The swampiness of the zone is high (about 50%).
Flat-hilly peatlands represent a mosaic complex of hillocks and hollows. The height of the mounds ranges from 30 to 50 cm, rarely reaching 70 cm. The area of the mounds is up to several tens, less often hundreds of square meters. The shape of the mounds is lobed, round, oval, elongated or ridge-like; the tops of the mounds are occupied by lichens, mainly Cladonia milis and Cladonia rangiferina. Less common are Cetraria nivalis, C. cucullata, Cladonia amanrocraea. The slopes of the hillocks are covered with green mosses. Aulacomnium turgidium, Polytrichum strictum, Dicranum elongatum are abundant. Among the flowering plants, the strongly oppressed Ledum palustre and Rubus chamaemorus grow in clusters. Between them are fragments of dicrane-lichen associations. The hollows are heavily watered with a continuous carpet of sphagnum mosses from Sph. lindbergii, Sph. balticum, Sph. subsecundum, Sph. Jensenii. Drepanocladus vernicosus is less common in hollows, Drepanocladus fluitans is common, Carex rotundata is common, Carex chordorrhiza is less common, Cephalozia fluitans sometimes grows. Along with swamps, wetlands are widespread, which are swampy shrub tundras with Betula papa and willows, sometimes with Ledum palustre, swampy moss tundras with Betula papa and Ledum palustre, hummocky tundras with Eriophorum vaginatum.
Area of hummocky bogs occupies the northern part of the forest zone and the southern forest-tundra. The swampiness of the area is high. The mounds are found singly, but more often they are located in groups or ridges 1-2 km long, up to 200 m wide. Single mounds have a height of 2-2.5 m, soil mounds 3-5 m, ridge mounds reach a height of 8-10 m. Diameter the bases of the mounds are 30-80 m, the slopes are steep (10-20°). Inter-hill depressions are elongated, occupied by cotton grass-sphagnum and sedge-sphagnum oligotrophic or eutrophic hollows, sometimes with small lakes in the center. The surface of the largest mounds is broken by cracks up to 0.2-0.3 m deep. At the base of the mounds, sphagnum mosses grow and a layer of shrubs, mainly Betula papa, is developed. Higher up the slope, lichens predominate. They are also typical for flat peaks, often subject to wind erosion.
The hummocky peatlands are topped with peat up to 0.6 m thick, under which lies a highly ice-saturated mineral core consisting of ice and loamy, silty-loamy, less often sandy loam material. The mineral core, in addition to ice-cement and its individual crystals, contains numerous ice layers, the thickness of which reaches several tens of centimeters and usually increases downwards, the number of layers also decreases downwards.
North Ob peat-bog region It is a poorly drained lacustrine-alluvial plain composed of medium- and fine-grained sands with clearly defined horizontal layering.
The area is characterized by extremely high swampiness. Peat deposits occupy more than 80% of the territory; form complex systems, covering flat interfluves and high river terraces. Dominated by raised convex, heavily watered sphagnum peatlands with ridge-lake complexes on the flat tops and ridge-lake-hollow complexes on their slopes.
Areas with well-drained areas of peat bogs are insignificant and are confined to the territory with the highest surface elevations. Fuscum and pine-sphagnum phytocenoses with a large number of different lichens are widespread here.
Lowland peat deposits are located mainly on the first terraces above the floodplain of large rivers.
Deposits of high peat bogs are shallow, on average about 2 m. poorly decomposed fuscum, complex, and hollow types of structure predominate.
Kondinskaya peat-bog region It is a vast alluvial and lacustrine-alluvial plain composed of layered sandy and clayey deposits. For the left bank of the river. Konda and the right bank of its lower reaches are characterized by the presence of rugged topography. The region is characterized by extremely high water content. A significant part of the Kondinsk region is confined to an area of intense tectonic subsidence and is therefore characterized by the predominance of accumulation processes and the dominance of poorly drained swamps. Only the western part of the region, where denudation processes predominate, is characterized by low swampiness. The river beds are weakly incised. In the spring, the hollow waters of these rivers overflow widely and do not enter the banks for a long time. Therefore, river valleys are swamped over a large area; Near-terrace swamps are heavily flooded during high water. For the river basin Konda is characterized by the predominance of upland ridge-lake, ridge-lake-hollow and ridge-hollow peat deposits.
Lowland, sedge, reed, reed, birch-reed peat bogs are confined to river beds.
Transitional sedge-sphagnum, woody-sphagnum and sphagnum bogs are found on low terraces and in places where they join into bog systems. There are also complexes formed along the lines of surface intra-fallow flow of swamp waters.
The gradual tectonic subsidence of the surface affects the extremely high water content of the territory, which contributes to the intensive development of regressive phenomena in the swamps, the destruction of the sphagnum turf of ridges, hollows, an increase in the area of hollows due to the degradation of ridges, etc.
Among the swamps there are a huge number of lakes. Some of them are completely peated, but most have been preserved open mirror water among peaty shores.
In the river basin Kondy, the main type of peat deposit is raised, in which a complex type of structure predominates, which is due to the dominance of ridge-hollow complexes. Fuscum, Scheuchzeria-sphagnum and Magellanicum deposits are somewhat less common.
Transitional types of deposits make up peat bogs mainly on the second terrace of the river. Konda and its tributaries, and are also found along the edges of high-moor peat deposits, around mineral islands, or are confined to mesotrophic grass and moss swamps. The most common type of deposit is transitional swamp.
Low-lying deposits are found in river floodplains, forming narrow strips confined to overgrown rivers of high-moor swamps.
Analysis of spore-pollen diagrams dates the Kondin peatlands to the early Holocene. Peat bogs are of ancient Holocene age, the depth of which exceeds 6 m.
Middle Ob peat-bog region It is a lacustrine-alluvial and alluvial plain, composed on the surface mainly of cover deposits, underlying either lacustrine layered clays, or light loams, siltstone and sandy strata.
The territory is characterized by the development of progressive and predominant accumulation processes, which determines the predominant distribution of poorly drained swamps and constantly swampy forests. Only in the north of the region, where denudation processes predominate, are relatively drainable swamps found.
The region is characterized by the dominance of raised sphagnum bogs with ridge-lake-hollow and ridge-hollow complexes. The edges of swamps located at lower hypsometric levels (within the first floodplain terraces and floodplains of small lakes) are usually eutrophic or mesotrophic. The deposit of their central parts is represented by fuscum and complex types of structure and has a depth of 4-6 m.
Large peatlands on first-order watersheds are divided into three categories. On flat, level plateaus of watersheds, peatlands have a strongly convex surface with steep slopes and a flat central part. The difference in the levels of the center and edges is 4-6 m. The central main part of such peat bogs is represented by a fuscum deposit or a complex raised peat and bears lake-denudation or ridge-lake vegetation complexes on the surface, and ridge-hollow vegetation on the slopes.
On one-sidedly elevated watersheds with a gently concave asymmetrical surface, raised peat bogs give a drop in surface elevations from an elevated slope to a lower one.
The thickness of the peat layer also decreases in the same direction. The deepest part of such peatlands is usually represented by a fuscum type of structure with a ridge-lacustrine complex of vegetation on the surface. In the direction to the opposite slope of the watershed, the fallow becomes a complex upland with a ridge-hollow complex in the vegetation cover. The shallow peripheral area with a transitional swamp deposit bears the vegetation of sphagnum swamps on the surface.
On symmetrical watersheds with a flat plateau, sometimes raised peat bogs with a complex surface line are observed: two evenly raised caps are separated by a trough up to 2-3 m deep. Such peat bogs are composed mainly of raised fuscum or complex peats. On the gangs, the vegetation cover is represented by a ridge-lake complex, in the trough area - by sphagnum swamps, often giving rise to rivers. A. Ya. Bronzov explains the formation of such massifs by the mergers of two (sometimes several) peat bogs with separate pockets of swamping. In some cases, the formation of a deflection could occur during the breakthrough and outpouring of internal waters and partly the most liquefied and plastic peats from the peat bog, followed by subsidence of the peat deposit.
On second-order watersheds, peatlands occupy interfluves that have undergone significant dissection. The depth of the erosion incision here reaches 20-30 m. This is the nature of the watersheds between large rivers flowing approximately parallel to each other in their middle reaches.
In upland conditions, large peat deposits of the raised type with a predominance of fuscum deposits and with ridge-lake and ridge-hollow vegetation complexes on the surface are located on the watersheds of occurrence.
Basically, the Middle Ob region, as well as the Vasyugan region located to the south, are territories of almost continuous swamps. Swamps here completely cover watersheds of the first and second orders, terraces and river floodplains. Peat bogs predominate, total area which is about 90%.
Tym-Vakh peat-bog region occupies the Tym-Vakh interfluve and is composed of lacustrine-alluvial deposits. Geographically, it is confined to the Middle Vakh Plain and is characterized by high swampiness, which drops sharply in the northeastern part, where surface elevations reach 140 m.
Poorly drained raised sphagnum bogs with ridge-hollow-lake and ridge-hollow complexes dominate the watersheds and fourth terraces. They are also found on low terraces and are confined to the hollows of ancient drainage, where accumulation processes dominate. The deposit is characterized by great homogeneity and is composed of complex raised, Scheuchzerian and fuscum peat.
The deposit of transitional swamps is represented by transitional swamps and forest-swamp types of structure. Lowland peatlands are rare and are confined mainly to floodplains and low terraces. The deposit of lowland bogs is composed of sedge peat.
Ket-Tym peat-bog region occupies the area between the Keti and Tym rivers and extends east to the Yenisei. The watershed of the Ob and Yenisei has a clearly defined slope here with an increase in surface elevations to the east. The interfluve is composed of lacustrine-alluvial and deluvial deposits and is divided by a highly developed hydrographic network into a large number of small interfluves.
Due to the fact that the region is located within the contour of positive structures, the dominance of denudation processes determines the spread of well-drained swamps here. Regressive phenomena are less pronounced, there is a tendency for ridges to transgress, or ridges and hollows are in a state of dynamic equilibrium. The surface of the interfluve plateau has a clearly defined grivny relief. In some places, the dissected relief is leveled by a peat deposit 2-6 m deep - fuscum - or complex type structures on ridges, and in depressions - a transitional swamp or mixed swamp deposit with a lower horizon of low-lying sedge peat with a thickness of 1.5 m. Some ridges are ridges rising above the peat deposit, filling the depressions between the ridges by 2-10 m. The width of the ridges is up to 5 km. They are composed of sandy sediments and are usually overgrown with taiga forest of pine, fir, cedar, and birch. The peatlands of the inter-ridge depressions are represented by transitional swamp and mixed swamp types of structure. On the upper part of the slope of the watershed towards the floodplain in the lower reaches of the Keti and Tym rivers there are often small round peat bogs of suffosion depressions (from 10 to 100 ha, rarely more) with transitional and upland deposits, less often with lowland deposits.
The slopes of the watersheds are eroded, weakly dissected or almost undivided by terrace ledges, cloak-like covered with peat deposits, forming large peat bogs that stretch for long distances along the course of both rivers. Closer to the bottom of the watershed, these peatlands are composed of lowland deposits, higher up the slope - transitional, and in the upper sections of the slope - highland. On them, often in the upper part of the slope, rather large lakes with sapropel deposits at the base are scattered among the upper deposits.
In the upper reaches of the Keti and Tym rivers, the narrow terraces of both river valleys are covered with peat. Narrow peatlands stretched along rivers are often composed of transitional deposits. Raised, weakly watered pine-shrub-sphagnum bogs are confined here to the watershed plain. The ridge-hollow complex is developed in the central parts of the largest peat bogs.
Lowland and transitional swamps are widespread on the first and partially on the second terraces of the river. Obi. Especially a lot of mesotrophic and eutrophic sedge, sedge-sphagnum, sedge-hypnum, tree-sedge bogs are found on the right bank terraces of the river. Ob, between the Ketyu and Tym rivers. The average thickness of raised bogs is 3-5 m, lowland 2-4 m. Raised bogs are composed of fuscum, complex and Scheuchzerian-sphagnum types of structure. The deposit of mesotrophic swamps is represented by transitional swamp and forest-swamp types of structure. The deposit of lowland bogs is composed of sedge peat.
In the modern vegetation cover of bogs with a transitional deposit, one can observe an admixture of oligotrophic species, indicating the transition of peat formation to the oligotrophic type stage.
A special feature of the Ket-Tym region is the significant distribution of transitional and lowland peatlands compared to other peat-bog areas of the forest zone, where exclusively raised bogs are dominant.
Tavdinskaya peat-bog region It is a flat, sometimes gently undulating plain, composed of lacustrine-alluvial and alluvial sandy-loamy deposits.
Geographically, its central part is confined to the southern half of the Khanty-Mansi Lowland, where accumulation processes predominate and the greatest swampiness occurs. Its northwestern edge extends into the Tavdo-Kondinskaya Upland, and its southern edge into the Tobol-Ishim Plain. The swampiness of the area is high. A significant area is occupied by poorly drained lowland peat deposits, the deposits of which are composed mainly of sedge and sedge-hypnum types of structure with a small participation of deposits of the forest-bog and forest subtypes. The thickness of the deposits is small (2-4 m), peat deposits 5 m deep are occasionally found. On flat watersheds, small high-moor peatlands with deposits 6-7 m thick are common, often folded almost to the mineral soil with fuscum peat of a low degree of decomposition. There are many lakes on the surface of peat deposits, which at one time served as centers for the formation of most peat deposits in the region.
Vasyugan peat-bog region is a vast, slightly elevated plain experiencing tectonic uplift. It is composed of alluvial and subaerial sandy-loamy deposits. In the north and east of the region, lacustrine-alluvial deposits are common; in the south, subaerial loess-like loams extend into its boundaries. The location of the area to the contours of positive structures determines the distribution of relatively drained swamps. Poorly drained swamps occupy the Demyan-Irtysh interfluve and depressions of the Ob-Irtysh watershed, where accumulation processes are developed.
In general, the region is characterized by high swampiness (up to 70%), especially its western part, where swampiness in some places reaches 80%.
Raised sphagnum bogs with ridge-hollow-lake and ridge-hollow complexes are confined to the flat tops of watersheds. The slopes are less swampy. From the periphery, watershed raised sphagnum bogs are bordered by transitional sphagnum, grass-sphagnum areas of bogs. The deposit of raised bogs is composed of fuscum, complex, hollow and Scheuchzerian types of peat. The stratigraphy of lowland and transitional bogs is dominated by sedge and woody-grass peat species.
In the middle part of the watersheds, low-lying slope deposits occur in very flat depressions. Moisturize them groundwater type of perched water from higher areas of watersheds. At the base of the peatlands lie deoxidized silty calcareous loams, which enrich the deposit with a significant amount of mineral salts. The nature of the vegetation cover indicates that the hard-water regime currently exists. The peat deposit is represented by sedge-hypnum and hypnum types of structure. The thickness of the deposit is from 1.5 to 4.5 m.
Their areas are small, and they alternate with areas of sedge and swamp type of structure with a deposit depth of 1 to 3.5 m. The edges of lowland deposits of the swamp subtype are represented by lowland forest (pine, birch) and forest swamp, wood-sedge, wood-sphagnum, swamp forest types of structure with deposit thickness from 1 to 2.8 m.
The upland areas in the form of islands lie among the lowland deposits. Their peat layer is represented predominantly by the fuscum type of structure and reaches a thickness of 6 m. The world's largest watershed heterogeneous peat deposit, Vasyuganskoe, with an area of over 5 million hectares, is located in the region. Lowland peatlands generally do not form large areas in the region and, in addition to the slopes of watersheds, occupy mainly elongated areas in river valleys.
On low terraces, heavily swamped, lowland sedge-hypnum bogs predominate; lowland and transitional woody-sphagnum, woody-herbaceous bogs develop in the near-terrace part. Floodplains are swamped mainly in the upper reaches of rivers, where lowland sedge, sedge-willow, tree-sedge and forest swamps are formed. In their vegetation cover under the canopy of birch, Carex caespitosa and C. wiluica form high hummocks; in the inter-tussock depressions there is a large amount of forbs.
Deposits of the transitional type are located either at the contact of upland deposits with swampy forests, or at the contact of upland and lowland areas. In both cases, these are most often heavily watered deposits with a thin peat layer (1.5-2 m) and a vegetation cover of herbaceous plants(Carex lasiocarpa, C. rostrata, Scheuchzeria palustris) and from hydrophilic sphagnum mosses (Sph. obtusum, Sph. majus, Sph. fallax, Sph. jensenii), forming a smooth, semi-submerged carpet.
The thickness of the peat layer in floodplain peat bogs does not exceed 1.5-2 m. Their deposits of sedge, Scheuchzeria, wood-sedge or birch peat were in conditions of variable moisture with the participation of river waters, so its ash content is relatively increased.
The Vasyugan region is characterized by intensive peat accumulation. The average thickness of peat deposits is 4-5 m. Their age dates back to the early Holocene. The areas of swamps up to 8 m deep are of ancient Holocene age.
Ket-Chulym peat-bog region characterized by less peat compared to Ket-Tymskaya, which is explained in the geomorphological features of the region. The watershed Ket-Chulym plateau has a significantly greater degree of erosional dissection under the influence of the main water arteries. The rivers here cut deeply into the surface of the watersheds and have well-formed but narrow alluvial terraces. This caused a decrease in groundwater. Therefore, the total peat content in the Ket-Chulym region is reduced to 10%.
The relief of the watershed Ket-Chulym plateau is characterized by small saucer-shaped depressions of suffusion origin. They predetermine here basically
location and type of peat bogs. The most widespread in the peat bogs of suffosion depressions is the transitional swamp deposit with a total thickness of the peat layer from 1 to 4.5 m. Rare deposits are less common in them, mainly fuscum, complex and Scheuchzerian-sphagnum with a depth of up to 3-6 m. Flat suffosion depressions 1-2 m deep are occupied by cotton grass-sphagnum or magellanicum deposits. Lowland deposits in suffosion depressions are rare and are represented by forest, tree-sedge, multi-layer forest-fen and sedge types of structure. They fill the deepest basins, in which the thickness of the peat suite reaches 4-5 m.
In the Ket-Chulym region, a certain pattern is noted in the distribution of near-terrace peat deposits. In the middle part of the river. Ulu-Yul peatlands are small in size and located on sharply defined terraces. Downstream of the river, the terrace ledges are smoothed out, the surfaces of the terraces expand, and the area of peat deposits increases. The latter acquire an elongated shape and are stretched parallel to the river. Near the mouth of the river. The Ulu-Yul terraces are even less pronounced and peat deposits merge with each other, covering the surface of several terraces.
On terraces and in the near-terrace parts of river valleys, peat bogs are smaller in area (in comparison with the peat bogs of the Ket-Tym region) and, without merging into large-scale massifs, on the terraces they form chains of isolated deep-lying peat deposits extended parallel to the river, often of lowland type with forest, wood-sedge or sedge deposit.
Tura-Ishim peat-bog region It is a lacustrine-alluvial plain composed of sandy-loamy deposits and is characterized by the predominance of denudation processes. The area is heavily swamped. Lowland swamps dominate: sedge, sedge-hypnum, birch-sedge. Raised pine-sphagnum bogs occupy small areas. The most waterlogged central parts of the interfluve are occupied by raised ridge-hollow bogs.
In general, this is an area of high swampiness of weakly dissected gently flat wide river valleys with large lowland sedge-hypnum bogs at the bottoms of terraces and along their slopes and with medium-sized raised and transitional peat bogs on watersheds. The total swampiness of the region is up to 40%.
An example of a peat deposit of the first terraces above the floodplain is “Tarmanskoye”, located in the valley of the river. Tours. It stretches along the river for up to 80 km and adjoins the ledge of the main bank. Its deposit is almost entirely composed of sedge-hypnum and sedge peats, confirming the existence of ground nutrition.
The deposit includes within its boundaries a significant number of primary lakes of a rounded-elongated shape with an emerging orientation along the terrace. At the base of the lakes there are highly mineralized sapropels, which indicates forest-steppe conditions during the formation of the lakes. In the lower horizons of the deposit or on the edges of the deposit, high ash content of peats is observed as a result of clogging of the deposit with colluvial drifts.
North Baraba peat-bog region watershed sedge-hypnum bogs in the north borders on the Vasyugan peat-bog region, in the south on the South Barabinskaya region and is a gently undulating, weakly dissected plain. The region is composed of loess-like loams. There is little peat. It is dominated by small low-lying peatlands, such as borrowed areas, with an area of 10 to 100 hectares. The eastern margin, confined to the positive contours of the structures, is characterized by the development of relatively well-drained swamps. More than half of the peat area is lowland peat (54%) and approximately 27% is upland; The percentage of transitional peatlands here is relatively large (19%).
In the central part of the region there are many lakes, depressions and peat deposits. In the western part of the region, on the slopes of the Tara-Tartas interfluve, the main area of sedge-hypnum bogs is concentrated. Hypnosis swamps develop in low-lying elements of the relief, mainly in places where hard-water groundwater flows emerge, along the slopes of watersheds or in the near-terrace parts of river valleys. Therefore, a slightly increased ash content (up to 8-12%) is characteristic of hypnotic peats and peat deposits. The ash content of some near-terrace hypnotic peat bogs averages 6-7%. The same percentages are used to measure the ash content of the sedge-hypnum peat bogs of the Tara-Tartas interfluve.
Towards the east, sedge-hypnum peat bogs give way to their leading position in the lowland type to forest-bog and forest deposits. The latter are located here along the edges of peat deposits, in the central areas of which, as well as in areas with a more elevated bottom topography, there are islands of upland deposits. Moreover, the fuscum fallow is usually peripheral in relation to the complex upland one, which is located in the center, carrying a ridge-lake complex of vegetation on the surface.
Despite the increased carbonate content of the underlying rocks, the relatively low occurrence of groundwater, recharge from atmospheric precipitation, as well as partial uplift of the territory create favorable conditions for the gradual transition of lowland swamps to the oligotrophic stage of development. In the river valleys directly adjacent to the river ridges, the richest in floristic composition are the woody and herbaceous swamps (sogr). In that part of the valley where anoxic groundwater flows and colluvial water does not penetrate, sedge-hypnum bogs are formed. In addition to typical mosses, there are sedge and sedge-grass bogs, and in the east there are reed bogs, characteristic of the grass bog zone.
In the riverine parts of watersheds, along the banks of the upper reaches of rivers, and in the depressions of terraces, transitional forest swamps are widespread. Watershed lowland sedge-hypnum and hypnum bogs usually have a simple structure and are composed of sedge-hypnum and sedge peat species. Presence of ryams (high sphagnum islands) characteristic feature sedge-hypnum bogs of the North Barabinsk region. Hypnosis deposits are more typical for swamps on low terraces, where soluble calcium salts predominate in the water-mineral nutrition. In terms of high levels of decomposition and ash content, the deposit of bogs on watershed plains differs from the deposit of peat bogs on low terraces, which have a more complex stratigraphy. Here you can find grass-hypnum, cotton grass-sedge, reed-sedge, reed-sedge, sedge-sphagnum types of peat.
The bottom layers of the deposit are usually composed of reed or sedge-reed types of structure. Peat species of the woody group play a significant role in the structure of deposits of lowland near-terrace and floodplain-near-terrace bogs. Transitional forest swamps are widespread. They form in the interfluves, in the terraces above the floodplain and in the near-terrace parts. The deposits of these swamps are represented by transitional forest and forest-swamp types of structure.
In the ryams, the upper horizons of the deposit (up to 2-4 m) are represented by fuscum peat with separate layers of Magellanicum, Angustifolium, cotton grass-sphagnum, pine-cotton grass and pine-shrub types of peat. The bottom layers of the deposit are usually represented by peat of transitional and lowland types. The average depth of peat deposits on watersheds is 2-3 m; on low terraces the peat thickness increases to 5 m compared to the Vasyugan region. The beginning of the peat formation process dates back to the early Holocene.
Tobol-Ishim peat-bog region located west of the river. Irtysh and crosses the interfluve of Ishim and Tobol in the middle reaches. The surface of the territory is quite dissected and well drained. The swampiness of the region does not exceed 3%. It is dominated by small lowland swamps such as borrows with an area of 10 to 100 hectares. The location of the positive contours of the structures determines the development of predominantly well-drained peat deposits here.
Rough terrain, poorly developed hydrographic network, waterproof horizon located close to the surface, slow runoff surface waters led to the formation in the interridge spaces of a huge number of lakes, usually round or oval with shallow depths, a flat bottom and heavy overgrowth. Lakes are often adjacent to or surrounded by small, shallow-lying sedge-reed bogs. During the period of snowmelt, the fields are filled with meltwater, turning into temporary shallow reservoirs, often interconnected, and then the flow through such a chain of lakes connected by the fields has the character of a river. There are very few isolated lakes. By chemical composition The waters of the lake, sometimes located in close proximity to one another, are distinguished by significant diversity. Salty, bitter and fresh lakes lie almost nearby.
Relatively larger fields, characteristic of the northern part of the region, surround lakes with fresh and brackish water. The thickness of the deposits of these fields is up to 1-1.5 m. It is composed of highly mineralized sedge, sedge-reed and reed peats with an average ash content of 20-30%. Their vegetation cover is dominated by reed, reed-sedge and sedge (C. caespitosa, C. omskiana) phytocenoses.
Smaller areas of borrowings are common in the southern part of the region around salt lakes. They are very shallow, composed of reed peat with a high degree of decomposition and high ash content. The reed association, and less often the sedge association, predominate in their vegetation cover.
In the sandy spaces of the Tobol region and in the northern part of the region on the right bank of Ishim, lowland peat bogs (sedge and sedge-hypnum) have separate areas (such as ryams) with high-lying deposits composed of fuscum peat of a low degree of decomposition, with a convex surface and secondary vegetation cover of pine trees. shrub phytocenosis that developed as a result of repeated fires.
In small basins of suffoses of ionic origin, shallow “split” peatlands of lowland type are found. They developed in solonetz microrelief depressions - “saucers”. Salinization and the subsequent process of swamping lead to the appearance of areas of swampy meadows with Carex intermedia, which are exclusively characteristic of this territory, which are subsequently covered with thickets of shrubs, mainly Salix sibirica, and a birch stand.
There are also treeless “spike” swamps with sedge hummocks on the surface, surrounded on the periphery by tall-trunked birch. They formed in deeper and more moist depressions with diverse wetland vegetation, greatly varying in composition in some cases: with hummocks of Carex omskiana, sometimes with Salix sibirica in the shrub layer. Such peat bogs are never covered over the entire area with birch; the deposits in them are tree-sedge.
South Barabinsk peat swamp region large borrow-ryam peatlands are composed of alluvial-lacustrine and loess-like deposits. Its soil cover is dominated by peat-bog soils, solonetzes and solonchaks (up to 60%); Chernozems occupy a smaller area, podzolic soils and etc.
Soil salinization processes (including peat soils) are widespread in the region. Their mineralization naturally increases from north to south. The general calm relief of the region is complicated by low ridges elongated in the southwestern direction in combination with interridge depressions. The hydrographic network is quite dense. Both lakes and river beds are abundantly overgrown with aquatic and wetland vegetation and imperceptibly merge with wetlands. Very often the depressions between the ridges are completely swamped. Characteristic of the Baraba topography are suffusion depressions on various surface elements and a large number of lakes, different in size, origin and chemical composition of water.
The area's swampiness is approximately 33%. Lowland reed-sedge peatlands predominate here, constituting up to 85% of the total wetland area. The remaining 15% is distributed between the upper ryam deposits and the transition deposits of their peripheral areas.
Zaimishchno-ryam peatlands are most widespread in the eastern half of the region, their areas here reach several thousand hectares, and the area of ryams - high, rising up to 8-10 m above the level of the ryam - up to a thousand hectares. Towards the west, the areas of borrowings decrease, ryams are less common, and their height decreases.
The emergence of high-lying ryam deposits among lowland deposits is associated with the feeding of ryam areas with fresh and slightly saline lake or surface stagnant waters. The lakes are still preserved as open reservoirs adjacent to the ryams; sometimes traces of them remain at the base of the ryam deposit in the form of a thin layer of sapropel.
The degree of decomposition of borrowed peats, as a rule, exceeds the species indicator (30-50%), the average ash content is 20%. The deposit of borrowings is composed of highly mineralized peats of the swamp group: reed, reed-sedge and grass (with a predominance of remains of light grass and reed grass in the fiber). The total thickness of the borrowing deposits reaches 1.5 m. In the vegetation cover, in the direction from the center to the periphery, reed, sedge-reed and sedge (or grass-sedge) phytocenoses are successively replaced. The latter borders on saline meadow vegetation. Areas fed by lake waters did not experience variability in moisture and salt conditions. Protected from the influence of saline groundwater by the surrounding low-lying deposits, they were overgrown with alloys of Sph. teres, the reservoirs passed into the peat bog stage; gradually, as the deposits grew, they came out of the influence of lake waters and continued to develop as atmospherically fed peat bogs. Dominance in these areas of Sph. fuscum maintains high humidity in the deposit and low temperature. Sph. fuscum created its own substrate and microclimate even in forest-steppe conditions and over thousands of years deposited powerful deposits of high-moor peat.
The modern vegetation cover of the ryams is secondary and arose under human influence. The degree of decomposition of the fuscum deposit is always reduced, which is facilitated, in addition to increased humidity and low temperature, apparently by its increased acidity, which inhibits microbiological processes. At the contact of the ryams and the dams themselves, there is usually a belt of transitional deposits with mesotrophic plant cover.
In addition to large ryam peat bogs, the South Barabinsk region is characterized by numerous small peat bogs in saucer-shaped depressions and depressions of suffusion origin along the interfluves and ridges.
Transitional and lowland forest swamps usually form a narrow belt around ryams or are confined to depressions of the mesorelief. In the latter case, forest swamps are genetically related to birch trees. Spike swamps dominated by Carex intermedia are typical for the southern part of the region. Birch-reed swamps here are confined to flat, highly mineralized lowlands and represent one of the initial phases of swamping. The total area of the ryams is insignificant. They are found mainly in the northern half of the region.
According to the radiocarbon method, the absolute age of the ryam with a thickness of 3.1 m dates back to the Middle Holocene, and the borrows with a depth of 1.35 m - to the Late Holocene. The processes of swamping are facilitated by the gradual tectonic uplift of the area, which causes the disintegration of rivers and lakes into separate bodies of water.
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1. West Siberian Lowland
2.
The West Siberian Lowland is the third largest
largest plain on our planet after
Amazonian and Russian. Its area is about 2.6
millions
square
kilometers.
Length
West Siberian
lowlands from north to south (from the coast
Kara Sea to the mountains of Southern Siberia and
semi-deserts of Kazakhstan) is about 2.5
thousand kilometers, and from west to east (from
The West Siberian Plain is the most
the inhabited and developed (especially in the south) part of the Urals to the Yenisei) - 1.9 thousand kilometers.
Siberia. Within its boundaries are located
Tyumen, Kurgan, Omsk, Novosibirsk
and Tomsk region, eastern regions
Sverdlovsk and Chelyabinsk regions,
a significant part of the Altai Territory, western
regions of the Krasnoyarsk Territory as well as northern and
northeastern regions of Kazakhstan
3.
The surface of the West Siberian Lowland is flat with quite
slight elevation difference. However, the relief of the plain is quite
diverse. The lowest areas of the plain (50-100 m) are located
mainly in the central and northern parts. Along the western, southern and
On the eastern outskirts there are low (up to 200-250 m) hills.
A clearly defined strip of hills is formed in the inner part
plains of Siberian Uvaly (average height - 140-150 m), extending from the west
from the Ob east to the Yenisei, and the Vasyugan Plain parallel to them.
The foundation of the West Siberian plate is covered with a cover of loose marine and
continental rocks (clays, sandstones) with a total thickness of over 1000 m (in
foundation depressions up to 3000-4000 m).
There are industrial oil and natural gas fields (West Siberian
oil and gas basin). In the area of Khanty-Mansiysk, Krasnoselsky,
Salym and Surgut regions, in layers of the Bazhenov formation at a depth of 2 km
Russia has the largest shale oil reserves.
4.
The climate of Western Siberia is continental and quite harsh.
4 main reasons shaped the climatic conditions of the territory:
1 reason - the amount of solar radiation received by the territory;
Reason 2 - the distance from the Atlantic and Pacific oceans determined
continentality
3rd reason – the flatness of the territory, allowing penetration
air masses from the north and south;
4th reason - mountains that fenced off Western Siberia from the Atlantic and
Central Asian air masses.
The north has a climate with cold, windy winters and cool summers, with
moving from north to south, the continental climate increases.
This is expressed in an increase in temperature, a decrease in the amount
precipitation, shortening the duration of the transition seasons of the year, due to
low temperatures here are excessive, but in the southern part they are sufficient
moisture and in combination with low altitudes of the territory and weak
drainage leads to severe swampiness - almost up to 70%.
The average January temperature decreases from -15(C in the southwest to -30(C)
in the northeast of Western Siberia. Average temperature in July
increases from +5(C in the north to +20(C) in the south.
5.
On the territory of the West Siberian Lowland
More than 2000 rivers flow through it. Their total length is about 250 thousand
kilometers. The largest are the Ob, Yenisei and
Irtysh. Not only are they navigable, but also
are used to produce energy. They feed in
mainly due to melt water and rain (in summer-autumn
period). There are also a large number of lakes here.
In the southern regions they are filled with salt water. The West Siberian Lowland holds the world record for
number of swamps per unit area (area
wetland area of about 800 thousand square
kilometers). The reasons for this phenomenon are
the following factors: excess moisture, flat
relief, permafrost and peat capacity,
available here in large quantities, keep
significant mass of water.
6.
7.
Natural zones of the West Siberian Plain
Due to the large extent of the West Siberian Lowland with
north to south and the uniformity of the relief in its aisles is present
five natural areas: tundra, forest-tundra, forest, forest-steppe and
steppe. In all zones, fairly large areas are occupied by lakes and
swamps. Broad-leaved and coniferous-deciduous forests here
are absent, and the forest-steppe zone is quite insignificant.
The tundra zone occupies a large area, which is explained by the northern
position of the West Siberian Plain.
Located further south
forest-tundra zone. As mentioned above, the forests in this area
mostly conifers.
The forest-swamp zone occupies about 60% of the territory of the West Siberian Lowland. The strip of coniferous forests is followed by a narrow zone
small-leaved (mainly birch) forests. Forest-steppe zone
is formed in conditions of flat-flat relief. Lying here on
at shallow depths, groundwater is the cause of large
number of swamps. In the extreme southern part of West Siberian
lowlands there is a steppe zone, which for the most part
plowed
8.
Ancient glaciation greatly influenced plant and animal world
Western Siberia. When the glacier retreated, the north of the plain was conquered
tundra and taiga, although previously there were broad-leaved forests, in
inhabited by mammoths, woolly rhinoceroses, and giant deer. By
the remains of tree trunks in the swamps indicate that the forest boundary
was located several hundred kilometers further north than at present
time.
The least diversity in all zonal areas of Western
The plants of Siberia are different. On average, the flora of Western Siberia is poorer
approximately 1.5 times compared to adjacent regions, especially large
gap for taiga and tundra zones. Higher relative
The fauna of Western Siberia is characterized by diversity. Yes, at four
There are 80 main orders of mammals in Western Siberia
species. The bird fauna is most diverse, the main
Some of the species in Western Siberia are migratory. In general
number of bird species in Western Siberia in any zonal area
is not significantly inferior to adjacent regions, and in terms of waterfowl and
semi-aquatic is superior to them.
9.
The fauna of the plain is presented as
forest and steppe species. Here
there are elk, roe deer, wolves, etc.
Representatives of the world also meet
birds (ptarmigan, gull). In Northern Kazakhstan and forests
There were brown bears in Kostanay. Now they
no, apparently they went to safer places
habitats. Rarely in recent years
There are moose and Siberian roe deer.
The reason for this is poaching. IN
local rivers and lakes have released muskrats,
brought from America. Gradually she
is taking root. Favorable natural
conditions allow large animals to live here
number of birds. In the wide open spaces
swans and geese are found in reservoirs.
10.
A lot of minerals are found in the West Siberian Plain.
The Sokolovsko-Sarbaiskoye and Kacharskoye deposits produce
iron ore. A mining and processing plant operates in the city of Rudny
plant In the Ayatskoye and Lisakovskoye deposits, large
nickel and coal reserves. Chromite deposits were explored,
bauxite, cobalt. There are many building materials available.
11.
— Western Siberia is one of the largest
low plains globe.
— Rich in a variety of natural resources.
— The climate is continental, quite harsh.
— Rich in rivers, lakes, swamps.
— The zonality of its nature is clearly expressed - from
tundra to steppes.
12.
thanks for
attention!
West Siberian Lowland
English РусскийRules
Features of Western Siberia
The West Siberian Lowland, or plain, is the third largest plain in the world after the Russian. Its area is about 2.6 million km2. From the harsh coast of the Kara Sea it stretches to the foothills of the mountains of Southern Siberia and the semi-deserts of Kazakhstan for 2500 km, and from the Urals to the Yenisei - for 1900 km.
The boundaries of the plain are clearly defined natural boundaries: in the north - the coastline of the Kara Sea, in the south - the foothills of the Kazakh hills, Altai, Salair and Kuznetsk Alatau, in the west - the eastern foothills of the Urals, in the east - the valley of the Yenisei River.
The huge West Siberian Lowland, almost completely covered by a mantle of anthropogenic sediments, is a young epihercynian (epipaleozoic) plate. This is the most significant oil and gas basin in Russia.
In the west, the boundaries of the plate are outcrops of Paleozoic rocks along the eastern slope of the Urals and Pai-Khoi, and further to the north along the coastline of the Vaygach and Novaya Zemlya islands.
In the southwest, in the Turgai trough, the border with the Turan plate located to the south is conventionally drawn along the watershed of the Ubagan and Turgai rivers. The southern and southeastern boundaries are determined by Paleozoic outcrops in the Kazakh and Altai-Sayan regions.
The eastern boundary of the plate is drawn along the river valley. Yenisei, along the outcrops of pre-Paleozoic and Paleozoic rocks. In the lower reaches of the river. The Yenisei border is completely arbitrary; it is usually carried out in an arc from the village. Dudinka to the outcrops of Paleozoic rocks at the western end of Taimyr. Within the Kara Sea, the northern boundary of the plate has not yet been precisely established.
There are three structural levels in the structure of the West Siberian plate: geosynclinal, intermediate and platform. In relation to the Meso-Cenozoic platform cover, the first two are usually considered as the foundation.
Nowhere in the world can one find such a huge space with such a flat topography, seemingly sloping towards its center. Crossing the plain, you see vast planes - not a hillock, not a ridge. This relief was formed by loose river sediments and ancient glacial sediments, which covered the Paleozoic plate with a thick sedimentary cover (3-4 thousand m). Horizontal layering of sedimentary layers - main reason flat terrain of the plain.
The relief of the West Siberian Plain was also affected by glaciation. But the glacier here did not cross 60 degrees. northern latitude.
In the south of the plain, during floods of rivers covered in ice in the north, lake and river sediments - sands and loams - were deposited over enormous areas.
Glaciation affected not only the relief, but also the flora and fauna of the West Siberian Plain. When the glacier retreated, the north of the plain was conquered by tundra and taiga, although previously there were broad-leaved forests inhabited by mammoths, woolly rhinoceroses, and giant deer. Based on the remains of trunks in the swamps, it can be judged that the forest border was located several hundred kilometers further north than at present.
The continental climate in the vast West Siberian Plain increases as you move from north to south. This is expressed in an increase in the annual temperature range, a decrease in precipitation, and a shortening of the duration of spring and autumn - the transition seasons of the year.
At the junction of temperate air masses with tropical ones, cyclones arise that bring rain. At the beginning of summer, this front acts in the south - the steppe zone receives moisture (about 300 mm per year). In July, hot air dominates the entire south of the plains, and cyclones move north, bringing precipitation to the taiga zone (500 mm per year). In August, the front reaches the tundra, where up to 250 mm falls per year.
In winter, cyclones of the Arctic front operate at the junction of temperate and arctic air masses. This softens the frosts in the north, but due to high humidity and strong winds The harshness of the climate here manifests itself even with less frost. The West Siberian Plain is rich in rivers, lakes, and swamps, the distribution of which across the territory clearly shows a dependence on the topography and the zonal ratio of heat and moisture.
The largest river of the West Siberian Plain is the Ob with its tributary Irtysh. This is one of the greatest rivers in the world. In Russia, it ranks first in length (5410 km) and basin area (2990 thousand km 2).
In addition to the Ob and Irtysh, among the large rivers of the region one can name navigable ones: Nadym, Pur, Taz, and Tobol.
Among the numerous lakes, filling glacial lake basins predominate. In terms of the number of swamps, the West Siberian Plain is also a world record holder: nowhere else in the world is there such a wetland area with an area of 800 thousand km 2 as here. A classic example of swampiness is the Vasyugan region, a geographical area lying between the Ob and Irtysh rivers. There are several reasons for the formation of such vast wetland areas: the presence of excess moisture, flat topography, permafrost, low air temperatures, and the ability of peat, which predominates here, to retain water in quantities many times greater than the weight of the peat mass. The climate of Western Siberia is more continental and harsher than in the east of the European part of Russia, but milder than in the rest of Siberia. The large extent of the plain from north to south allows several latitudinal zones to fit here - from the tundra in the north to the steppes in the south.
The enormous size of the West Siberian Plain and its flat topography make it possible to trace the latitudinal-zonal changes in natural landscapes especially well. home distinguishing feature tundra - the severity of the climate. Adapting to harsh conditions, tundra plants prepare winter buds in the fall. Thanks to this, in the spring they quickly become covered with leaves and flowers, and then bear fruit. There is a lot of different plant food in the tundra, so many herbivorous birds nest here.
The forest-tundra is the first zone, moving south, where a summer thermal regime is observed for at least 20 days a year, when average daily temperatures exceed 15? C. Here the tundra alternates with sparse and rather low trees. More than half of the territory of Western Siberia is occupied by forest and swamp zones. The interfluve spaces are dominated by swamps, and the slopes of river valleys and elevated areas (groves) are occupied by taiga forests. In the northern part of the plain spruce and cedar forests dominate, in the southern part - spruce and cedar forests with an admixture of fir and birch. To the south of the taiga there is a zone of deciduous forests, which in Western Siberia stretches in a narrow strip from the Ural Mountains to the Yenisei River.
The West Siberian forest-steppe stretches in a narrow strip from the Urals to the foothills of the Salair Ridge. The abundance of lake basins is a feature of this zone. The shores of the lakes are low, partly swampy or overgrown with pine forests. In the Kulda pine forests they live together with steppe species, field pipits, jerboas, and taiga species - flying squirrel, capercaillie.
This area is distinguished by large fertile soils, on which good crops of grains and vegetables can be grown.
The natural resources of the West Siberian Plain are very diverse. Oil and gas reserves in such fields as Urengoy, Medvezhye, and Surgut place Western Siberia among the world leaders. Its territory also contains 60% of Russia's total peat reserves. In the south of the plain there are rich salt deposits. The great wealth of Western Siberia is its water resources. In addition to surface water - rivers and lakes - huge reservoirs of groundwater have been found. The biological resources of the tundra and forest-tundra are of great economic importance - this, it would seem, is not rich life zones. It produces a significant amount of fur and game, and there is a lot of fish in its rivers and lakes. In addition, the tundra is the main breeding area for reindeer. The taiga of Western Siberia has long been famous for its fur and timber production.
Brown coal deposits are associated with ancient sedimentary rocks of Triassic and Jurassic age, the total thickness of which is more than 800-1000 m. In the Tyumen region, its reserves are estimated at 8 billion tons.
However, the main wealth of Western Siberia is oil and gas deposits. It has been established that this plain is a uniquely rich oil and gas province of the Earth.
To date, more than 350 oil, gas and gas condensate fields have been explored. For the last 3 decades, Western Siberia has held the lead in oil and natural gas production in Russia.
Searches in the depths of Western Siberia for “black gold” and “blue fuel” made it possible to discover large reserves of iron ore in the north of the Novosibirsk region. But these vast and varied riches are not so easy to master. Nature protected the oil and gas fields of the region from humans with thick swamps and frozen soils. It is extremely difficult to build in such soil conditions. In winter people severe frosts, high air humidity, and strong winds interfere. In the summer, there are numerous blood-sucking creatures - midges and mosquitoes, tormenting people and animals.
Map of Western Siberia
General information about Western Siberia
Time in Western Siberia: in the Yamalo-Nenets Autonomous Okrug, Tyumen Region, Khanty-Mansiysk Autonomous Okrug - Yugra time is 2 hours ahead of Moscow. In the Omsk region, Tomsk region, Novosibirsk region and the Altai Republic, time is 3 hours ahead of Moscow. In the Kemerovo region, time is 4 hours ahead of Moscow.
Western Siberia is a region of Russia, stretching 2,500 km from the Arctic Ocean to the highlands of the Kazakh hills and 1,900 km from the Ural Mountains to the Yenisei. About 80% of the area of Western Siberia is located within the West Siberian Plain, which gradually rises in the southeast and gives way to the foothills of Altai, Salair, Kuznetsk Alatau and Mountain Shoria.
Western Siberia includes: Yamalo-Nenets Autonomous Okrug, Tyumen region, Omsk region, Khanty-Mansiysk Autonomous Okrug - Ugra, Tomsk region, Novosibirsk region, Kemerovo region, Altai Territory, Altai Republic.
Languages spoken in Western Siberia: Russian, Altai, Kazakh.
Territory Western Siberia: 3,561,165 km².
Borders Western Siberia: With Kazakhstan, With China, With Mongolia, with the Kurgan region, with Sverdlovsk region, with the Komi Republic, with the Nenets Autonomous Okrug, with the Krasnoyarsk Territory, with the Republic of Khakassia, with the Republic of Tuva.
Largest cities Western Siberia: Tobolsk, Tyumen, Omsk, Nefteyugansk, Nizhnevartovsk, Surgut, Tomsk, Novosibirsk, Berdsk, Kemerovo, Prokopyevsk, Novokuznetsk, Barnaul, Biysk, Rubtsovsk.
Highest mountain peaks Western Siberia: G.
Sinyukha (1,210 m), Verkhniy Zub (2,176 m), Aktru (4,075 m),
Argamdzhi (3,511 m), Belukha (4,506 m), Kolji Khan (1,992 m), Maashey-bash (4,173 m), Muzdy-Bulak (3,050 m), . Sarlyk (2,506 m), Payer (1,499 m), Harnaurdy-Keu (1,246 m).
Largest lakes Western Siberia: Saltaim, Tenis, Ik, Chany, Teletskoye, Aya.
Largest rivers Western Siberia: Ob, Ishim, Irtysh, Tobol, Katun.
International airports Western Siberia: Barnaul (Barnaul), Kemerovo (Kemerovo), Kogalym (Kogalym), Nizhnevartovsk (Nizhnevartovsk), Tolmachevo (Novosibirsk), Omsk-Central (Omsk), Surgut (Surgut), Bogashevo (Tomsk), Roshchino (Tyumen), Khanty- Mansiysk (Khanty-Mansiysk),
Population Western Siberia: 14.2 million people (Russians - 75%, Altaians - 5%, Ukrainians - 3%, Tatars - 3%, Nenets - 2%, Kazakhs - 0.6%, Bashkirs - 0.4%, Azerbaijanis - 0.3%, others - 10 .7%).
Population density Western Siberia: 8.68 people/km².
Religion Western Siberia: Christians - 73%, Muslims - 17%, Catholics - 9%, others - 1%.
GDP per capita in Western Siberia: RUR 770,700
Population below the poverty line V Western Siberia:15 %.
Unemployment V Western Siberia: 5 %.
Literacy Rate V Western Siberia: 99%.
Geographical location of the West Siberian Plain
Note 1
The West Siberian Plain is a vast plain that makes up almost 80% of the territory of Western Siberia. Its total area is almost $2 million km²$. It is limited in the west by the Ural Mountains, and in the east by the Yenisei Valley. North coast The plains are washed by the waters of the seas of the Arctic Ocean. The Kazakh small hills are considered the southern border.
From north to south the plain extends for almost $2000$ km. Most of it is located in temperate latitudes. But the northern outskirts are located beyond the Arctic Circle. The general slope of the relief determines the predominant influence of the Arctic Ocean on the formation of the climate and nature of the plain. Due to its remoteness and protection from the Atlantic and Pacific oceans, continental air masses dominate over the territory of the West Siberian Plain.
History of the formation of the plain
For a long time, the territory of modern Western Siberia was the bottom of an ancient paleoocean. Therefore, the crystalline foundation of the platform is covered with a thick layer of sedimentary rocks. Due to the large thickness of the foundation and difficult local conditions (swampy areas and harsh climate) tectonic structure not yet fully studied.
Some scientists believe that the plate is based not on one lithospheric block, but on several geoblocks separated by deep tectonic faults.
Even in the Mesozoic, the territory of the plain was covered with seas. At the beginning of the Cenozoic, the sea retreated. But during the Ice Age, the northern territories of the plain were covered by continental glaciation. Therefore, after the ice melted, a significant area of the plain was covered with moraine deposits. Since the West Siberian Plain was flooded by the sea for a long time, its surface has an almost flat topography.
Tectonic structures of Western Siberia
The following tectonic structures are distinguished on the territory of the West Siberian Plain:
- Yamalo-Gydan syneclise;
- Nadym-Tazovskaya syneclise;;
- Khantei anteclise;
- Ket-Vakh anteclise;
- Khantymansi syneclise;
- Chulym syneclise;
- Messoyakha megaswell;
- Pursky Trench;
- Khudoseisky gutter;
- Koltogorsk-Urengoy rift zone.
Features of the tectonic structure include the fact that between the cover of sedimentary rocks and the pre-Paleozoic crystalline foundation of the West Siberian Plate lies a transitional layer of Triassic and Jurassic rocks. Geologists believe that its formation is associated with movements of the foundation. As a result of these movements, a unique intracontinental rift zone was formed. It has graben-like depressions in which sedimentary and volcanogenic coal-bearing horizons of considerable thickness (up to $5$ km) accumulated. But further development of the rift zone did not spread. Therefore, a new ocean did not form.
The influence of tectonics on relief and minerals
Note 2
Thanks to the peculiarities of the geological history of the formation of the West Siberian Plain, an almost flat relief was formed over a vast territory. The processes of accumulation of thick loose deposits predominate. Accumulative processes contribute to the leveling of the epihercynian basement.
The insignificant amplitude of tectonic movements was the reason for the low-lying hypsometric status of the plain. The total elevation difference does not exceed $150 $ m. On the territory of the plain, areas with low and high relief are distinguished. Due to the structure of the foundation, there is a general decrease in relief from south to north. The West Siberian Plain is characterized by uniform relief
In the thickness sedimentary rocks horizons of fresh, mineralized water were discovered. There are hot springs. The main wealth of the region is oil and gas deposits.
The eastern territories of Russian Asia open from the Ural Mountains to the West Siberian Plain. Its settlement by Russians began in the 16th century, from the time of Ermak’s campaign. The expedition's route ran from the south of the plain.
These territories are still the most densely populated. However, we must remember that already in the 11th century the Novgorodians established trade relations with the population on the lower Ob.
Geographical position
The West Siberian Plain is washed from the north by the harsh Kara Sea. In the east, along the border of the Yenisei River basin, it neighbors the Central Siberian Plateau. The southeast is protected by the snowy foothills of Altai. In the south, the Kazakh small hills became the border of flat territories. The western border, as stated above, is the oldest mountains of Eurasia - the Ural Mountains.
Relief and landscape of the plain: features
A unique feature of the plain is that all the heights on it are very weakly expressed, both in absolute and relative values. The area of the West Siberian Plain, very low-lying, with many river channels, is swampy on 70 percent of the territory.
The lowland stretches from the shores of the Arctic Ocean to the southern steppes of Kazakhstan and almost all is located within the territory of our country. The plain provides a unique opportunity to see five natural zones with their characteristic landscape and climate conditions.
The relief is typical of low-lying river basins. Small hills alternating with swamps occupy the interfluve areas. The south is dominated by areas with saline groundwater.
Natural areas, cities and plain regions
Western Siberia is represented by five natural zones.
(Swampy area in the tundra of the Vasyugan swamps, Tomsk region)
The tundra occupies a narrow strip in the north of the Tyumen region and almost immediately turns into forest-tundra. In the extreme northern areas you can find massifs of a combination of lichens and mosses of Western Siberia. The area is dominated by swampy terrain, turning into open forest-tundra. The vegetation here is larch and thickets of bushes.
The taiga of Western Siberia is characterized by dark coniferous zones with a variety of cedar, northern spruce and fir. Occasionally you can find pine forests, occupying areas between swamps. Most of the lowland landscape is occupied by endless swamps. One way or another, the whole of Western Siberia is characterized by swampiness, but there is also a unique natural massif here - the largest swamp in the world, the Vasyugan swamp. It occupied large territories in the southern taiga.
(Forest-steppe)
Closer to the south, nature changes - the taiga brightens, turning into forest-steppe. Aspen-birch forests and meadows with coppice appear. The Ob basin is decorated with pine island forests that arose naturally.
The steppe zone occupies the south of the Omsk and southwestern parts of the Novosibirsk regions. Also, the area of distribution of the steppe reaches the western part of the Altai Territory, which includes the Kulundinskaya, Aleiskaya and Biyskaya steppes. The territory of ancient water drainages is occupied by pine forests
(Fields in the taiga of the Tyumen region, Yugra)
The West Siberian Plain provides the opportunity for active land use. It is very rich in oil and almost all of it is lined with production rigs. The region's developed economy attracts new residents. Big cities the northern and central parts of the West Siberian Plain are well known: Urengoy, Nefteyugansk, Nizhnevartovsk. In the south are the cities of Tomsk, Tyumen, Kurgan, Omsk.
Rivers and lakes of the plain
(Yenisei River on hilly-flat terrain)
Rivers flowing through the West Siberian Lowland flow into the Kara Sea. The Ob is not only the longest river of the plain, but together with its tributary the Irtysh, it is the longest water artery in Russia. However, there are also rivers on the plain that do not belong to the Obi basin - Nadym, Pur, Taz and Tobol.
The territory is rich in lakes. They are divided into two groups according to the nature of their occurrence: some were formed in pits dug by a glacier passing through the lowlands, and some - in places of ancient swamps. The area holds the world record for swampiness.
Plain climate
Western Siberia in its north is covered with permafrost. A continental climate is observed throughout the plain. Most of the plain's territory is very susceptible to the influence of its formidable neighbor - the Arctic Ocean, whose air masses unhindered dominate the lowland region. Its cyclones dictate precipitation and temperature patterns. In areas of the plain where the Arctic, subarctic and temperate zones converge, cyclones often occur, leading to rain. In winter, cyclones generated at the junctions of the temperate and arctic zones soften the frosts in the north of the plains.
More precipitation falls in the north of the plain - up to 600 ml per year. Temperatures in the north in January on average do not rise above 22°C, in the south at the same time frosts reach 16°C. In July in the north and south of the plain, it is 4°C and 22°C, respectively.
Geological structure of Western Siberia
The base of the West Siberian Plain is a young plate of the same name. The plate in the east borders on the Siberian platform, from the south Paleozoic structures of Central Kazakhstan, Altai, and the Salair-Sayan region approach it, and in the west the border goes with the folded system of the Urals. Determining the northern border is difficult because it is covered by the waters of the Kara Sea. The base of the West Siberian plate is the Paleozoic basement, with an average depth of $7$ km. In the mountainous regions of the southeastern part, ancient Precambrian and Paleozoic rocks come to the surface, and within the West Siberian Plain they are hidden by a thick cover of sedimentary rocks.
The West Siberian plate began its formation in the Mesozoic era, in the Upper Jurassic period. At this time, the area between the Urals and the Siberian platform subsided, resulting in a huge sedimentation basin. Marine transgressions more than once captured the West Siberian Plate during its development. In the Lower Oligocene, the plate was freed from the sea and turned into a huge lacustrine-alluvial plain. A new uplift of the northern part of the plate occurs in the late Oligocene and Neogene, and in the Quaternary period of the Cenozoic era the plate descends again. The development of the plate occurs in such a way that it resembles the process of oceanization and the development of swamps.
The slab foundation is divided into two parts:
- External side belt. It is represented by slopes of a folded mountain frame, descending towards the central part of the depression. The foundation is located at a depth of $2.5$ km. In the southwest of the Kustanai saddle it approaches the surface at only $300$-$400$ m.
- Inner area. It is divided into two stages: the southern stage – the Middle Ob meganteclise with a basement depth of up to $4$ km and the northern stage – the Yamalo-Taz megasyneclise descended to a depth of up to $12$ km.
Between the sedimentary cover and the foundation of the plate lies a transitional complex, the age of which is Triassic-Lower Jurassic. The foundation underwent extension and, as a result, the formation of an intracontinental rift zone with a system of graben-like depressions occurred. The depressions were the site of accumulation of sedimentary-volcanogenic and sedimentary coal-bearing continental strata up to $5$ km thick. The transitional complex also contains igneous rocks, represented by basaltic lavas and tuffs.
The development of the intracontinental rift zone within Western Siberia did not lead to the formation of a new ocean. Almost continuous formation of the cover under conditions of plate subsidence took place in the Mesozoic and Cenozoic eras. It is composed of sandy-siltstone coastal-continental deposits and marine clayey and sandy-clayey strata. Their thickness reaches $4$ km in the southern part and $7$-$8$ km in the northern part. Numerous local structures are expressed in the sedimentary cover. These are mainly oil and gas reservoirs.
The general orographic features of Western Siberia were already formed by the end of the Neogene. The sea had a level lower than the modern one by $200$-$250$ m, and a significant part of the bottom of the Kara Sea was dry land. At the end of the Neogene, a general cooling of the climate and the development of Quaternary glaciation began.
Relief of Western Siberia
The development of the modern relief of Western Siberia was greatly influenced by the geological development of the territory, tectonic structure and exogenous relief-forming processes. The unevenness of the foundation was leveled out as a result of the accumulation of a thick layer of loose sediments. The periphery of the plain has a small amplitude of uplifts, reaching $100$-$150$ m. The central and northern parts of the plain are characterized by subsidence of $100$-$150$ m. However, a number of lowlands and hills can be distinguished. The plain is open to the north, towards the Kara Sea and has the shape of a stepped amphitheater.
There are three altitude levels on the territory of the West Siberian Plain:
- Level one has a height of less than $100$ m and occupies half of the territory;
- The second level is at an altitude of $100$-$150$ m;
- The third level is located in the range of $150$-$200$ m with small areas from $250$-$300$ m.
The edges of the plain have more high level and are represented by the North Sosvinskaya, Verkhnetazovskaya, Lower Yisei uplands, Priobsky plateau, Turinskaya, Ishimskaya, Kulundinskaya, Ketsko-Tymskaya plains. The northern and central parts of the plain are represented by areas below $100$ m. These are the lowest areas of the plain. The Nizhneobskaya, Nadymskaya, Purskaya, Tazovskaya, Kondinskaya lowlands have a height of less than $50$ m. In internal parts The plain passes through a strip of clearly defined hills - Verkhnetazovskaya, Numto ridge, Belogorsk continent, Lyulimvor.
From an orographic point of view, the elevation of the plain along the edges and the descent of the surface of the plate towards the center are clearly visible. The interior regions of the plain, where thick Mesozoic deposits occur, are already losing the clarity of expression in the relief of large basement structures. The number of inversion structures is growing. The Vasyugan Plain, for example, is nothing more than an anteclise located within a syneclise. Within the inner zone, under the conditions of recent subsidence, the formation of accumulative and stratified-accumulative plains took place. They are composed of Neogene-Quaternary loose sediments.
The types of morphosculptures created by exogenous relief-forming processes are located on the plain in the direction from north to south. Off the coast of the Kara Sea there are sea plains. They were formed in post-glacial times after the retreat of the sea. Moraine and fluvio-glacial plains are located to the south. Here they are adjacent to glacial, lacustrine-alluvial plains.
Minerals of Western Siberia
The main wealth of the West Siberian Plain are hydrocarbons - oil and gas. Experts estimate the area of promising oil and gas fields at $1.7 million sq km. Such large deposits as Samotlorskoye and Megionskoye, located in the Nizhnevartovsk region, are associated with the middle Ob region. Large deposits in the Surgut region - Ust-Balykskoye, Fedorovskoye, etc.
Natural gas in the Subpolar region - the Medvezhye, Urengoy fields, in the Arctic - Yamburgskoye, Ivankovskoye, etc. There is oil and gas in the Urals, and new promising fields have been discovered on the Yamal Peninsula. In general, more than $300 oil and gas deposits have been discovered on the plain.
In addition to hydrocarbons, large deposits are known in Western Siberia coal, the main reserves of which are located within Kuzbass. Kuznetsk coal reserves are estimated at $600 billion tons. Almost $30$% of these coals are coking. Greater thickness of coal seams and close location to the surface allow their development not only by mines, but also open method. Brown Kansk-Achinsk coals lie to the northeast of the Kuznetsk basin. In the largest Itat field, the thickness of the layers reaches $80$ meters, and the depth ranges from $10$ to $220$ meters. The cheapest coal in Russia is mined here. Anthracite coals are concentrated in the Gorlovka basin, located in the south of the Novosibirsk region. Brown coals of the Tyumen region have not yet been put into operation.
Of the fuel resources in the depths of the West Siberian Plain there is $50$% of all-Russian reserves peat.
Stands out for its reserves and ore base. Significant iron ore resources are concentrated in the Narym, Kolpashevo, and Yuzhno-Kolpashevo deposits. Brown iron ores occur here. Gornaya Shoria is characterized by magnesium ore deposits - Tashtagol and Sheregesh. In Altai there are the Inskoye and Beloretskoye fields. There are deposits of manganese ores and nephelines in the Kemerovo region. Place of Birth mercury in Altai.
The lakes of the Kulunda steppe contain reserves soda and salts.
Limestones in the Novosibirsk and Kemerovo regions.
Altai has significant reserves building materials.
In addition to minerals, Western Siberia is rich forest resources. Timber reserves account for $11$% of Russian reserves.
Note 1
Issues of protection and rational use of natural resources are also relevant for Western Siberia. The thoughtless use of resources can ruin the environment and lead to negative consequences.