General characteristics of the West Siberian Plain. Physical Geography - Western Siberia (West Siberian Plain)
The authors of all physical-geographical zoning schemes single out Western Siberia with an area of about 3 million sq. km. equally. Its boundaries coincide with the contours of the Epipaleozoic West Siberian plate. The geomorphological boundaries are also clearly defined, coinciding mainly with the isohypse of 200 m, and in the north with the coastline of the bays (bays) of the Kara Sea. Conventionally, only the borders with the North Siberian and Turan plains are drawn.
Geological development and structure. In the Precambrian, the small West Siberian Platform and the basement of the western part of the Siberian Platform (approximately up to the line coinciding with the Taz River bed) were formed. The Ural geosyncline formed between the East European and West Siberian platforms, and the Yenisei geosyncline between the Siberian platforms. During their evolution in the Paleozoic, folded structures were formed along the outskirts of the West Siberian Platform: Baikalids west of the Yenisei Ridge, Salairids north of the Kuznetsk Alatau, Caledonides north of the western part of the Kazakh Upland. These disparate structures were united by Hercynian folded areas, which, moreover, directly merged with the Hercynides of the Urals, Western (Rudny) Altai, and the eastern part of the Kazakh Upland. Thus, the nature of the West Siberian Plate can be understood in two ways. Given the “patchwork” of its foundation, it is often called heterogeneous but since most of it was formed in the Paleozoic, the plate is considered epipaleozoic. Noting the decisive role of the Hercynian folding, the slab is piled epihercynian.
Along with the long processes of basement formation, in the Paleozoic (as well as the Triassic and Early Jurassic), the cover was formed for an equally long time. In this regard, the Paleozoic-Early Jurassic sequences deposited on top of folded structures are usually distinguished into a special, “intermediate” or “transitional” stage (or complex), which geologists attribute either to the basement or to the cover. It is believed that the real cover was formed only in the Meso-Cenozoic (beginning from the middle of the Jurassic). The deposits of the cover overlapped the border zones of neighboring folded structures (the Siberian Platform, salairides of the Kuznetsk Alatau, Caledonides and Hercynides of the Rudny Altai, Kazakhstan, and the Urals) and noticeably expanded the territory of the West Siberian Plate.
crystalline folded foundation The plate consists of ancient (Precambrian and Paleozoic) metamorphic (crystalline schists, gneisses, granite-gneisses, marbles), volcanogenic and sedimentary rocks. All of them are crumpled into complex folds, broken into blocks by faults, cut through by intrusions of acidic (granitoids) and basic (gabbroids) composition. The relief of the foundation surface is very complex. If we mentally remove the deposits of the cover, a sharply dissected surface of the mountain structure will be exposed with height amplitudes of 1.5 km in the peripheral parts and much greater in the north of the axial zone. The depths of the foundation naturally increase towards the axial zone and within this zone in a northerly direction - from -3 to -8 ... -10 km, according to some data, even more. The ancient West Siberian platform is fragmented into many blocks, most of which are deeply subsided, and some (for example, the Berezovsky block) are relatively uplifted and can be traced on the surface (the Berezovskaya Upland with maximum absolute heights of over 200 m). The margins of the West Siberian Plate correspond to the slopes of neighboring folded structures, which are a kind of “shields”. In the inner parts of the plate there are syneclises (Omsk, Khanty-Mansiysk, Tazov and others), separated uplifts ( Vasyugan) and vaults(Surgut, Nizhnevartovsk and others). Within the Kemerovo region there is a part Teguldet depression with depths down to –2.5 km, strongly resembling the Minusinsk depression.
“Intermediate floor It consists of weakly dislocated and weakly metamorphosed strata of Paleozoic rocks overlying the basement of pre-Hercynian age (they are absent within the Hercynian structures), as well as Triassic trap rocks and coal-bearing terrigenous rocks of the Early Jurassic. At the end of the Permian and Triassic, an extensive zone of lithospheric extension arose in Siberia. It covered the Tunguska syneclise of the Siberian Platform and submeridional zones between the Urals and the Irtysh and Poluy rivers, as well as between 74 and 84 degrees E. Numerous alternating grabens and horsts appeared, linearly elongated in the submeridional direction (“key structure”). The trap magmatism covered almost the entire West Siberian Plate (and the neighboring Tunguska syneclise). In recent decades, forecasts have been made regarding a high degree of oil and gas content of the “intermediate” level.
Case It is composed of horizontally occurring strata of Meso-Cenozoic sandy-argillaceous rocks. They have a variegated facies composition. Almost until the end of the Paleogene, maritime conditions prevailed in the north, to the south they were replaced by lagoonal ones, and in the extreme south - by continental ones. From the middle of the Oligocene, the continental regime spread everywhere. Sedimentation conditions changed directionally. A warm and humid climate persisted until the end of the Paleogene, there was luxurious vegetation. In the Neogene, the climate became noticeably cooler and drier. In the strata of the Jurassic and, to a lesser extent, the Cretaceous age, a huge mass of organic matter accumulated. The organic matter dispersed in the sandy-clayey material sank into the depths of the earth's crust, where it was exposed to high temperatures and petrostatic pressure, which stimulated the polymerization of hydrocarbon molecules. At relatively shallow depths (up to about 2 km), long hydrocarbon chains arose, which led to the formation of oil. At great depths, on the contrary, only gaseous hydrocarbons were formed. Therefore, the main oil-bearing fields tend to the southern part of the West Siberian Plate with relatively small cover thicknesses, and the gas fields tend to the northern regions with the maximum depths of the basement.
Dispersed in the form of an insignificant admixture, hydrocarbons slowly rise to the earth's surface, most often reach the atmosphere and are destroyed. The existence of reservoirs (sandy and other rocks with a certain porosity) and seals (argillaceous, impermeable rocks) contribute to the preservation and concentration of hydrocarbons in large deposits.
Minerals. In the conditions of the cover of the West Siberian Plate composed of sedimentary rocks, only exogenous deposits are widespread. Sedimentary fossils dominate, and among them are caustobioliths (oil in the southern part of the plain; the largest field is Samotlor; gas in the northern part - Urengoy in the Pur river basin, Yamburg on the Taz Peninsula, Arctic on Yamal; brown coal - Kansk-Achinsk basin; peat, brown iron ore - Bakchar; evaporites of Kulunda and Baraba).
Relief. Orography and morphometry. The West Siberian Plain is considered an “ideal” lowland plain: its absolute heights are almost everywhere below 200 m. This level is exceeded only by tiny areas of the North Sosvinskaya Upland (including the Berezovskaya Upland), the Belogorsky Continent (the right bank of the Ob to the north of the mouth of the Irtysh), the eastern section of the Siberian Uvals ; more extensive uplands are located in the foothills of Altai, the Kazakh hills, and the Urals. For a long time, on hypsometric maps, the West Siberian Plain was painted over in a uniform green color. A detailed study revealed, however, that the orography of the region is no less complex than within the East European Plain. Plains with heights of more than 100 m (“highlands”) and less than 100 m (lowlands) are clearly distinguished. The most famous “hills” are: Siberian Ridges, Nizhneeniseiskaya, Vasyuganskaya, Barabinskaya, Kulundinskaya, (Pri) Chulymskaya; lowlands: Surgut Polissya, Kondinskaya, Severoyamalskaya, Ust-Obskaya.
Morphostructure. The morphostructure of the accumulative plain clearly predominates. Only along the outskirts, especially in the southwest, south, southeast, there are denudation plains, including inclined stratified plains.
Major events of the Pleistocene. The entire territory of Western Siberia was affected to some extent by glaciation on natural conditions, including morphosculpture. Ice came from the Ural-Novaya Zemlya and Taimyr-Putoransk centers, which were significantly inferior to the scale of the Kola-Scandinavian center. Three epochs of glaciation are most recognized: the maximum Samarovo (the first half of the Middle Pleistocene), the Taz (the second half of the Middle Pleistocene), and the Zyryanovsk (Upper Pleistocene). Synchronously with glacials appeared boreal transgressions, covering much larger areas than in the northeast of European Russia. At least in the northern part of Western Siberia, the glaciers were shelf glaciers and “floated”, carrying moraine material with ice. A similar picture is still observed in the waters of the Kara Sea, which is a natural continuation of the West Siberian Plain. Integumentary land glaciers operated south of the Siberian Ridges.
As now, the largest rivers flowed in accordance with the slope of the surface to the north, i.e. towards the glacier. The glacial tongue acted as a dam, to the south of which periglacial lakes (Purovskoye, Mansiyskoye, etc.) were formed, into which melted waters of the glacier also entered. This explains the much greater than in Eastern Europe, the role of hydroglacial deposits, and among them - outwash sands and plains.
Excessive water inflow into the periglacial lakes overwhelmed them, led to the “splashing” of water both to the north (which led to the formation of underwater runoff troughs, for example, the St. plains). Lake and river accumulation proceeded intensively here. But even these reservoirs overflowed, excess water flowed through the Turgai Strait into the lakes-seas of the Black Sea-Balkhash system.
In the extreme south of Western Siberia, fine silty material was transported to the far margins of the periglacial zone mainly by flowing waters, rarely by wind. Accumulating in arid climate conditions, it created strata of loess-like, mantle loams and loesses. Thus, it is possible to distinguish a number of zones of relict relief formation of the West Siberian Plain, successively replacing each other in a southerly direction: a. boreal-marine accumulation (Yamal, territories adjacent from the south and east to the Ob, Taz and Gydan bays); b. glacial accumulation (peripheral areas of the Subpolar Urals and Putorana); in. water-glacial accumulation (mainly glacial-lake - up to the parallel of the Irtysh mouth); the city of terminal moraines of the Samarovsky glacier (up to 59 degrees N), overlain by hydroglacial deposits of the Taz and Zyryanovsky glaciers; e. glacial-lake accumulation; e. river and “normal” lake accumulation; and. loess formation.
Zoning of modern relief formation and types of morphosculpture. The Pleistocene relief is intensively reworked by modern agents. In the south direction, the following zones are distinguished: a. sea relief; b. cryogenic morphosculpture; in. fluvial morphosculpture, arid relief formation.
The strongest indentation of the coastline and the low flat relief of coastal territories significantly increase the area marine relief formation. The littoral zone, flooded by the sea at high tide and released at low tide, is very wide. A certain role is played by wind surges on flat coastal areas and the effect of the sea on the supralittoral zone lying above the littoral zone. Particularly stand out layden up to several kilometers wide thermoabrasive dynamically developing coasts and low, but vast sea terraces.
cryogenic the relief is widespread in the north, from the tundra to the northern taiga subzone, inclusive. Polygonal soils, hydrolaccoliths, and heaving mounds are especially widely developed. The most significant role is played fluvial processes and forms: valley-watershed relief; in the southern regions of Western Siberia, ravines are developed in a cloak of loess-like loams and other rocks. There are large ravines, for example, in the city limits and in the vicinity of the city of Novosibirsk. In the steppe zone is manifested arid relief formation(steppe suffusion subsidence and deflationary saucers, less often primitive accumulative sand forms).
Since the relict and modern landforms are superimposed on each other, it is necessary to distinguish a number of “total” geomorphological zones.
Climate The West Siberian Plain is continental (with a continentality index of 51 - 70%). It occupies a natural place in the series of increasing the degree of continentality in the east direction: transitional from oceanic to continental (Fennoscandia) - temperate continental (Russian Plain) - continental (Western Siberia). The most important reason for this regularity is the weakening of the climate-forming role of the Atlantic in the channel of the western transport of air masses and the gradually increasing processes of their transformation. The essence of these processes is as follows: an increase in the severity of winters at practically the same summer temperatures and the resulting increase in the amplitudes of air temperature fluctuations; a decrease in the amount of precipitation and a clearer expression of the continental regime of precipitation (summer maximum and winter minimum).
As in the Urals (and for the same reasons, see the corresponding section of the manual), cyclonic weather prevails throughout the year in the northern part of the plain, and anticyclonic weather prevails in the southern part. In addition, the vast size of the territory determines the zonality of other climatic characteristics. The indicators of heat supply vary greatly, especially in the warm part of the year. As in the Russian Plain (see the corresponding section), summer isotherms thicken in the northern part (from 3 degrees on the Arctic coast to 16 degrees at the 64th parallel) and their rarefaction (up to 20 degrees at the 53rd parallel) in the southern part of the West Siberian Plain. The same can be said about the distribution of precipitation (350 mm on the coast of the Kara Sea - 500–650 mm in the middle zone - 300–250 mm in the south) and moisture (from a sharp excess - dryness indices of 0.3 - in the tundra to an optimum - close to 1 in the forest-steppes - and weak deficiency - up to 2 - in the steppe zone). In accordance with the above regularities, the degree of continentality of the climate of the plain increases in a southerly direction.
The large extent of the plain from west to east also influences. The decrease in average January temperatures in this direction in the northern part of the West Siberian Plain (from -20 to -30 degrees) has already been mentioned. In the middle zone of the region, a decrease in the amount of precipitation in the western part due to the impact of the barrier role of the Urals and an increase in the eastern part, in front of the barrier of the Central Siberian Plateau, is very indicative. In the same direction, the degree of continentality and severity of the climate increases.
In Western Siberia, typical Siberian features of the climate are manifested. These include, first of all, the general severity of winters, or at least their individual time periods: average January temperatures are in the range of -18 ... -30 degrees; on the Russian Plain, only the extreme northeast approaches such temperatures. A feature of the Siberian weather is the wide distribution of temperature inversions, despite the flatness of the region's relief. This is facilitated in part by the specificity of the air masses overcoming the Ural barrier (see the relevant section), and in part by the abundance of flat orographic basins. Characteristic for the climate of Western Siberia is the instability of the weather of the transitional seasons of the year and the high probability of frosts at this time.
It should be noted the sharp differences between the weather of the European part and Siberia. With increased cyclonic activity to the west of the Urals in Siberia, the probability of anticyclone dominance is high; in summer there is a predominance of cool rainy weather in the Russian Plain and hot dry weather in Siberia; mild snowy winters of the Russian Plain correspond to frosty winters with little snow in Siberia. The inverse relationship of weather takes place with a diametrically opposite change in the features of the baric field of the Russian Plain and Siberia.
Inland waters. rivers, related mainly to the Kara Sea basin (basins of the Ob, Pura, Taz, Nadym, Messoyakha and a number of small rivers), are predominantly snow-fed and belong to the West Siberian type of intra-annual runoff regime. It is characterized by a flood extended in time (over 2 months), but the excess of water consumption during the flood period over the annual average is small (4-5 times). The reason for this is the natural regulation of runoff: excess water during the flood is absorbed by very capacious floodplains and swamps. Accordingly, the summer low water is relatively weakly expressed, since the summer runoff is replenished at the expense of water “saved” during the flood. But the winter low water is characterized by very low flow rates, since there is only one very weakened source of power - groundwater. During this period, the content of oxygen catastrophically decreases in the rivers: it is spent on the processes of oxidation of organic substances contained in the water, and it does not penetrate well under the ice layer. Fish accumulate in pools, form dense mass accumulations, and are in a sleepy state.
The groundwater form a single system - the West Siberian hydrogeological basin (see its description in the general review). Their characteristics are subject to zonal distribution. In the polar and circumpolar parts of the plain, groundwater lies almost on the surface, it is cold and practically does not contain mineral (gyrocarbonates, silica) impurities. In this zone, the formation of groundwater is strongly influenced by permafrost; in the northern half of Yamal and Gydan, they are continuous, and to the south - insular. In the middle lane, as you move south, the depths of occurrence, temperature, and the degree of mineralization of the waters consistently increase. Calcium compounds appear in the composition of the solutions, then sulfates (gypsum, mirabilite), Na and K chlorides. Finally, in the extreme south of the plains, sulfates and chlorides play a leading role, so the water acquires a bitter and salty taste.
swamps in the conditions of a flat low-lying relief, which greatly complicates the drainage of soils and soils, they become one of the leading components of landscapes. The swamp areas and the degree of swampiness are very large (50 - 80%). Many researchers consider swamps to be aggressive natural habitats, capable not only of self-preservation, but also of constant expansion at the expense of forest landscapes. This becomes possible due to a directed increase in the degree of hydromorphism of forest PTCs due to the accumulation of water (excess moisture, poor drainage) and organic matter (peat). This process is irreversible, at least in the modern era.
Zoning is observed in the distribution of swamps. Tundra swamps develop on permafrost and polygonal soils, they are frozen and contain mainly mineral substances. Within the forest-tundra and forest zone, upland oligotrophic bogs with a convex surface and a predominance of sphagnum and sedge prevail in the vegetation. In the subtaiga zone, on raised and mesotrophic transitional bogs, often hummocky, with a flat surface, green mosses and marsh grasses are mixed with sphagnum and sedges. In the more southern areas, the predominance passes to low-lying hummocky eutrophic bogs with a concave surface and rich vegetation.
Lakes. Myriads of small thermokarst lakes (Yambuto, Neito, Yaroto, etc.) are scattered in the northern third of the West Siberian Plain. Medium-sized lakes of various genesis are very numerous in the middle zone (Piltanlor, Samotlor, Kantlor, etc.). Finally, the largest and relatively small relict often saline lakes are located in the south, within the Baraba, Kulunda, Ishim and other plains (Chany, Ubinskoe, Seletteniz, Kyzylkak, etc.). They are complemented by small saucer-shaped lakes of suffusion-subsidence genesis.
The structure of latitudinal zonality. The flatness of the surface of Western Siberia determines the ideal manifestation of the latitudinal zonality of the distribution of most of the components of nature. However, the dominance of hydromorphic intrazonal landscapes (swamps, floodplains, riverine spaces), on the contrary, makes it difficult to identify zones.
zonal spectrum, due to the large length of the plain along the meridian, it is extensive: three tundra subzones, two forest-tundra subzones, northern, middle and southern taiga, subtaiga, two forest-steppe subzones, two steppe subzones. This speaks in favor of recognition structure complexity zoning.
Outlines (“geometry”) of zones. In Western Siberia, the forest zone is narrowed. Its northern border is shifted to the south, especially in comparison with Central Siberia. Usually they talk about two reasons for this shift - geological and geomorphological (poor drainage of the surface, which does not create conditions for the development of the root system of trees) and climatic (insufficient heat supply and sharply excessive moisture in summer). The southern borders of the taiga and subtaiga, on the contrary, are shifted to the north under the influence of insufficient moisture for woody vegetation. The forest-steppe and steppe zones are also shifted to the north for the same reason.
Qualitative specifics of the West Siberian provinces of the zones. Tundra. To the north of the 72nd parallel there is a subzone of arctic tundra with scarce soil and vegetation cover confined to frost cracks (mosses, lichens, cotton grass, partridge grass on arctic tundra gleyed soils). Between the 72nd and 70th parallels, there is a subzone of moss-lichen tundra with an admixture of wild rosemary, cranberries, blueberries and other shrubs, as well as cotton grass. The shrub tundra subzone is dominated by shrub birch, willow, and alder on tundra-gley soils. In general, the zone is called permafrost-tundra; swamps and thermokarst lakes play a significant role. Tundra fauna with ungulate and Ob lemmings is characteristic.
forest tundra stretches in a narrow (50 - 150 km) intermittent strip in the west of the plain to the south, in the east north of the Arctic Circle. Against the background of the southern tundra, there are sparse and woodlands of Siberian larch and spruce on gley-podzolic soils.
Taiga (forested area). The dark coniferous taiga of spruce Picea obovata, fir Abies sibirica, cedar Pinus sibirica predominates; there is an admixture of Siberian larch Larix sibirica, and pine forests form extensive areas, especially in the western part of the plain. The degree of swampiness reaches a maximum. The soils are podzolic, often swampy and gleyed.
AT northern subzone(up to 63 - 61 degrees north latitude in the south), the forests are oppressed and sparse. Mosses and sphagnum grow under their canopy, shrubs play a lesser role. Continuous permafrost is almost ubiquitous. Significant areas are occupied by swamps and meadows. Dark coniferous and light coniferous taiga play almost the same role. Middle taiga subzone reaches in the south to 58 - 59 degrees north latitude. It is clearly dominated by dark coniferous taiga. Forests of good quality, with a developed shrub layer. Permafrost is insular. The swamps reach their maximum distribution. Southern subzone has a more elevated and dissected relief. There is no permafrost. The southern border of the taiga approximately coincides with the 56th parallel. Spruce-fir forests dominate with a significant admixture of small-leaved species, pine and cedar. Birch forms large massifs - belniki or white taiga. In it, the trees let in more light, which favors the development of the grassy layer. Soddy-podzolic soils predominate. Waterlogging is great, especially in Vasyugan. The southern taiga subzone enters the Kemerovo region in two sections.
Subtaiga zone of small-leaved West Siberian forests stretches in a narrow strip from the Middle Urals to the Kemerovo region, within which it occupies the interfluve of the Yaya and Kiya rivers. Birch forests stand out more often (warty birch, downy birch, Krylova and others), less often aspen-birch forests on gray forest and soddy-podzolic soils.
forest-steppe forms a relatively narrow strip stretching from the Southern and Middle Urals in the west to the foothills of the Altai, Salair and the Chulym River in the east; the eastern section of the zone is called the Mariinsky forest-steppe and is located within the Kemerovo region. Forest tracts (splits) of warty birch or birch and aspen grow on gray forest, often solodized or podzolized soils. They alternate with meadow steppes or steppe meadows of mesophilic grasses (meadow grass meadow, reed grass, steppe timothy grass), rich herbs and legumes (titan, clover, mouse peas) on leached and podzolized chernozems. The northern and southern subzones are distinguished with a forest cover of 20–25% and 4–5%, respectively (theoretically, more or less than 50%). The average plowing of the zone is 40%, pastures and hayfields occupy 30% of the total area.
Steppe the southern outskirts of the West Siberian Plain reaches the foothills of Altai in the east; to the east, in the pre-Salair part of the Kemerovo region, there is a small isolated “island” of the zone, called the “steppe core” of the Kuznetsk basin. Strictly speaking, it belongs to the Altai-Sayan mountainous country, but differs little from the West Siberian steppes. In the northern subzone, forb-cereal steppes grow on ordinary chernozems. The southern subzone of feather grass-fescue (cereal) steppes develops on southern low-humus chernozems and dark chestnut soils. Halophytes grow (or even dominate) on solodized soils and solonetzes. Plots of natural virgin steppes are practically absent.
Physical-geographical zoning. The ideally expressed flatness of the territory makes Western Siberia a standard for the physical and geographical zoning of the plains. In all variants of the zoning scheme of the USSR and Russia, this physical-geographical country stands out equally, which indicates the objectivity of its selection. Morphostructural (the predominance of an accumulative plain), geostructural (a single geostructure of a young plate), macroclimatic (dominance of a continental climate) criteria for the isolation of a physical and geographical country are understood by all authors of zoning schemes in the same way. The specificity of the structure of the latitudinal zonality of the West Siberian Plain is unique, individual and sharply contrasts with the dominance of the altitudinal zonality of the neighboring mountainous countries (the Urals, the Kazakh hills, Altai, Kuznetsk Alatau) and the combination of altitudinal and zonal patterns of Central Siberia.
Units second rank - physical and geographical areas- allocated according to the zonal criterion. Each of the regions is a segment of the complex zone within Western Siberia. The allocation of such zones can be carried out with varying degrees of generalization, which leads to inconsistency in their number. This manual recommends the identification of three zones and their respective areas, listed in the following text.
A. The area of marine and moraine plains of the tundra and forest-tundra zones.
B. Region of moraine and outwash plains of the forest zone.
B. The area of accumulative and denudation plains of the forest-steppe and steppe zones.
In all areas, using the genetic criterion, physical geographical provinces- units third rank. The essence of the criterion is disclosed in the relevant sections of the general review and in the coverage of the problem of zoning the Russian Plain (see Book 1 of this manual).
WEST SIBERIAN PLAIN (West Siberian Lowland), one of the largest plains in the world. It is located in the northern part of Asia, in Russia and Kazakhstan. The area is over 3 million km2, including 2.6 million km2 in Russia. The length from west to east is from 900 km (in the north) to 2000 (in the south), from north to south up to 2500 km. In the north it is washed by the Arctic Ocean; in the west it borders on the Urals, in the south - on the Turgai plateau and the Kazakh hills, in the southeast - on the mountains of Southern Siberia, in the east - along the valley of the Yenisei River with the Central Siberian plateau.
Relief. It is a low accumulative plain with a rather uniform relief, various forms of permafrost (common up to 59 ° north latitude), increased swampiness, and ancient and modern salt accumulation developed in the south in loose rocks and soils. Heights of about 150 m predominate. In the north, in the area of \u200b\u200bdistribution of marine accumulative and moraine plains, the general flatness of the territory is disturbed by moraine gently sloping and hilly-sloping (North-Sosvinskaya, Lyulimvor, Verkhne-, Srednetazovskaya, etc.) hills 200-300 m high, the southern border of which runs about 61-62 ° north latitude; they are horseshoe-shaped from the south covered by flat-topped elevations Belogorsky Continent, Sibirskie Uvaly, etc. In the northern part, permafrost exogenous processes (thermal erosion, heaving of soils, solifluction) are widespread, deflation occurs on sandy surfaces, and peat accumulation occurs in swamps. There are numerous ravines on the plains of the Yamal and Gydansky peninsulas and on the moraine uplands. To the south, the area of moraine relief is adjoined by flat lacustrine-alluvial lowlands, the lowest (height 40-80 m) and swampy of which are Kondinskaya and Sredneobskaya. The area not covered by the Quaternary glaciation (south of the line Ivdel - Ishim - Novosibirsk - Tomsk - Krasnoyarsk) is a weakly dissected denudation plain, rising (up to 250 m) to the Urals. In the interfluve of the Tobol and the Irtysh, there is an inclined, in places with ridges, lacustrine-alluvial Ishim plain (120-220 m) with a thin cover of loess-like loams and loess occurring on salt-bearing clays. It is adjacent to the alluvial Baraba lowland and Kulunda plain, where the processes of deflation and modern salt accumulation are developing. In the foothills of Altai there are the ridge-ridged Priobskoe plateau (height up to 317 m - the highest point of the West Siberian Plain) and the Chulym Plain. On the geological structure and minerals, see the article The West Siberian Platform, with which the West Siberian Plain is geostructurally connected.
Climate. Continental climate prevails. Winter in the polar latitudes is severe and lasts up to 8 months (the polar night lasts almost 3 months), the average January temperatures are from -23 to -30 ° C; in the central part, winter lasts up to 7 months, average January temperatures are from -20 to -22 °С; in the south, where the influence of the Asian anticyclone intensifies, winters are shorter at the same temperatures (up to 5-6 months). The minimum air temperature is -56 °С. In summer, the western transfer of Atlantic air masses predominates with intrusions of cold air from the Arctic in the north, and dry warm air masses from Kazakhstan and Central Asia in the south. In the north, summer is short, cool and humid with a polar day, in the central part it is moderately warm and humid, in the south it is arid and dry, with dry winds and dust storms. The average July temperature rises from 5°C in the Far North to 21-22°C in the south. The duration of the growing season in the south is 175-180 days. Atmospheric precipitation falls mainly in summer. The wettest (400-550 mm per year) are the Kondinskaya and Sredneobskaya lowlands. To the north and south, the annual precipitation gradually decreases to 250 mm.
surface waters. There are more than 2,000 rivers in the West Siberian Plain belonging to the basin of the Arctic Ocean. Their total flow is about 1200 km 3 of water per year; up to 80% of the annual runoff occurs in spring and summer. The largest rivers are the Ob, Yenisei, Irtysh, Taz and their tributaries. The feeding of the rivers is mixed (snow and rain), the spring flood is extended, the low water is long summer-autumn and winter. The ice cover on the rivers lasts up to 8 months in the north, up to 5 months in the south. The total area of lakes is more than 100 thousand km2. The largest lakes are located in the south - Chany, Ubinskoye, Kulundinskoye. In the north - lakes of thermokarst and moraine-glacial origin. There are many small lakes in the suffusion depressions (less than 1 km 2): on the Tobol-Irtysh interfluve - more than 1500, on the Baraba lowland - 2500, including fresh, salty and bitter-salty ones; there are self-sustaining lakes.
Landscape types. The uniformity of the relief of the vast West Siberian Plain determines the clearly pronounced latitudinal zonality of landscapes, although, compared with the East European Plain, the natural zones here are shifted to the north. On the Yamal, Tazovsky and Gydansky peninsulas, in conditions of continuous permafrost, landscapes of arctic and subarctic tundra with moss, lichen and shrubs (dwarf birch, willow, alder) cover on gleyzems, peat-gleyzems, peat-podburs and soddy soils were formed. Polygonal mineral grass-hypnum bogs are widespread. The share of primary landscapes is extremely insignificant. To the south, tundra landscapes and swamps (mostly flat-hummocky) are combined with larch and spruce-larch woodlands on podzolic-gley and peat-podzolic-gley soils, forming a narrow forest-tundra zone, transitional to the forest (forest-bog) zone of the temperate zone, represented by subzones of the northern, middle and southern taiga. Swampiness is common to all subzones: over 50% of the area of the northern taiga, about 70% - middle, about 50% - southern. The northern taiga is characterized by flat and large-hilly raised bogs, the middle taiga is characterized by ridge-hollow and ridge-lake bogs, the southern taiga is characterized by ridge-hollow, pine-shrub-sphagnum, transitional sedge-sphagnum and low-lying tree-sedge bogs. The largest marsh massif is the Vasyugan Plain. The forest complexes of different subzones, formed on slopes with different degrees of drainage, are peculiar. Northern taiga forest complexes on permafrost are represented by sparse and low-growing pine, pine-spruce and spruce-fir forests on gley-podzolic and podzolic-gley soils. The indigenous landscapes of the northern taiga occupy 11% of the area of the West Siberian Plain. Common to the forest landscapes of the middle and southern taiga is the wide distribution of lichen and shrub-phagnum pine forests on sandy and sandy loamy illuvial-ferruginous and illuvial-humus podzols. On loams in the middle taiga, spruce-cedar forests with larch and birch forests are developed on podzolic, podzolic-gley, peat-podzolic-gley and gley peat-podzols. In the subzone of the southern taiga, on loams, there are spruce-fir small-grass forests and birch forests with aspen on sod-podzolic and sod-podzolic-gley (including those with a second humus horizon) and peat-podzolic-gley soils. Primary landscapes in the middle taiga occupy 6% of the area of the West Siberian Plain, in the southern - 4%. The subtaiga zone is represented by park pine, birch and birch-aspen forests on gray, gray gley and soddy-podzolic soils (including those with a second humus horizon) in combination with steppe meadows on cryptogley chernozems, solonetsous in places. Indigenous forest and meadow landscapes are practically not preserved. Boggy forests turn into lowland sedge-hypnum (with ryams) and sedge-reed bogs (about 40% of the zone). Forest-steppe landscapes of sloping plains with loess-like and loess covers on salt-bearing tertiary clays are characterized by birch and aspen-birch groves on gray soils and solods in combination with forb-grass steppe meadows on leached and cryptogleyed chernozems, to the south - with meadow steppes on ordinary chernozems, in places solonetzic and saline. On the sands - pine forests. Up to 20% of the zone is occupied by eutrophic reed-sedge bogs. In the steppe zone, the primary landscapes have not been preserved; in the past, these were forb-feather grass steppe meadows on ordinary and southern chernozems, saline in places, and in the drier southern regions - fescue-feather grass steppes on chestnut and cryptogley soils, gley solonetzes and solonchaks.
Environmental problems and protected natural areas. In areas of oil production due to pipeline breaks, water and soil are polluted with oil and oil products. In forestry areas - overcutting, swamping, the spread of silkworms, fires. In agricultural landscapes, there is an acute problem of lack of fresh water, secondary salinization of soils, destruction of soil structure and loss of soil fertility during plowing, drought and dust storms. In the north - degradation of reindeer pastures, in particular due to overgrazing, which leads to a sharp reduction in their biodiversity. No less important is the problem of preserving hunting grounds and habitats of fauna.
Numerous reserves, national and natural parks have been created to study and protect typical and rare natural landscapes. Among the largest reserves are: in the tundra - the Gydansky reserve, in the northern taiga - the Verkhnetazovsky reserve, in the middle taiga - the Yugansky reserve, etc. A national park - Priishimsky Bory - has been created in the sub-taiga. Natural parks are also organized: in the tundra - Deer streams, in the northern taiga - Numto, Siberian Uvaly, in the middle taiga - Kondinsky lakes, in the forest-steppe - Bird's harbor.
Lit.: Trofimov V. T. Patterns of spatial variability of engineering-geological conditions of the West Siberian plate. M., 1977; Gvozdetsky N. A., Mikhailov N. I. Physical geography of the USSR: Asian part. 4th ed. M., 1987; Soil cover and land resources of the Russian Federation. M., 2001.
The West Siberian Plain is characterized by a harsh, fairly continental climate. The West Siberian Plain is the most inhabited and developed (especially in the south) part of Siberia. High summer temperatures in the southern half of Western Siberia are explained by the inflow of heated continental air here from the south - from Kazakhstan and Central Asia. Autumn comes late.
The relief of the plain is largely due to its geological structure. At the base of the West Siberian Plain lies the epi-Hercynian West Siberian Plate, the foundation of which is composed of intensely dislocated Paleozoic deposits. At the end of the Lower Oligocene, the sea left the West Siberian plate, and it turned into a huge lacustrine-alluvial plain.
Its great length from north to south determines the distinct zoning of the climate and significant differences in climatic conditions in the northern and southern parts of Western Siberia. The proximity of the Arctic Ocean also has a significant effect on the continental climate of Western Siberia. Cyclones often pass in the border zone of areas of high and low pressure. In the warm season, a lower pressure sets in over Western Siberia, and an area of higher pressure forms over the Arctic Ocean.
Most of the precipitation falls in the summer and is brought by air masses coming from the west, from the Atlantic. There are especially many of them in July and August, which is explained by intensive activity on the Arctic and polar fronts.
The extreme southern regions of Western Siberia are characterized by droughts, which occur mainly in May and June. The harsh climate of the northern regions of Western Siberia contributes to the freezing of soils and the widespread permafrost.
The rivers of Western Siberia, including the largest ones - the Ob, Irtysh and Yenisei, are characterized by slight slopes and low flow rates. Peculiar lakes - "fogs" - are found in the Ural part of the plain. A large area is occupied by the tundra zone, which is explained by the northern position of the West Siberian Plain. To the south is the forest-tundra zone. The forest-bog zone occupies about 60% of the territory of the West Siberian Plain.
Therefore, the width of the forest-steppe zone in Western Siberia is much less than on the East European Plain, and of the tree species it contains mainly birch and aspen. In the extreme southern part of the West Siberian Lowland, there is a steppe zone, which is mostly plowed up.
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The geographical position of the West Siberian Plain determines the transitional nature of its climate between the temperate continental climate of the Russian Plain and the sharply continental climate of Central Siberia. The study of the nature and natural resources of Western Siberia acquired a completely different scope after the Great October Revolution.
Many features of the nature of Western Siberia are due to the nature of its geological structure and history of development. The formation of the main folded structures of the basement of Western Siberia, which have a predominantly meridional direction, refers to the era of the Hercynian orogeny. The tectonic structure of the West Siberian plate is rather heterogeneous. The Mesozoic formations of Western Siberia are represented by marine and continental sandy-argillaceous deposits.
Flora of the West Siberian Plain
The suites of Neogene rocks, which come to the surface mainly in the southern half of the plain, consist exclusively of continental lacustrine-river deposits. The events of the Quaternary period had a particularly great influence on the formation of the landscapes of Western Siberia. Lower Quaternary deposits are represented in the north of the plain by alluvial sands filling buried valleys.
Some researchers of the northern regions of the country draw a more complex picture of the events of the Quaternary glaciation in Western Siberia. On the other hand, there are supporters of a one-time glaciation of Western Siberia.
At the end of the Zyryansk glaciation, the northern coastal regions of the West Siberian Plain again sank. In the tundra zone, relief forms are especially widely represented, the formation of which is associated with a harsh climate and the widespread distribution of permafrost.
The main elements of the relief of the West Siberian Plain are wide flat interfluves and river valleys. Due to the fact that the interfluve spaces account for a large part of the country's area, they determine the general appearance of the relief of the plain.
In connection with this summer, weak northerly or northeasterly winds predominate, and the role of western air transport noticeably increases. These include, for example, the Vasyugan Plain, which formed on the site of a gently sloping syneclise, and the Chulym-Yenisei Plateau, located in the basement trough zone.
one of the largest on earth. Takes b. h. Zap. Siberia, stretching from the coast of the Kara Sea in the north to the Kazakh uplands in the south, from the Urals in the west to the Central Siberian Plateau in the east. OK. 3 million km². Wide flat or gently sloping interfluves, separated by terraced valleys, predominate. Height amplitudes from 20 to 200 m (max. up to 300 m). In the north, moraine hills and ridges are combined with young marine and alluvial (river) plains; in the south, lacustrine and lacustrine-alluvial plains are interspersed with ridges ( Barabinskaya, Kulunda Plain ). Z.-S. R. covers a thick cover of sedimentary rocks, which contain large accumulations of oil and gas. The climate is continental, precipitation from 200 (tundra, steppes) to 600 (taiga) mm per year. dense river network Ob , Irtysh , Yenisei , Taz and their tributaries). many large ( vats , Ubinskoe etc.) and countless small lakes, incl. salty. Extensive marshes and swampy forests. The north is continuous, with insular permafrost in the center. In the extreme south there are solonetzes and solonchaks. On W.-S. R. all zones and subzones of the temperate zone are represented: tundra, forest-tundra, taiga, deciduous forests, forest-steppe, steppe.
Dictionary of modern geographical names. - Yekaterinburg: U-Factoria. Under the general editorship of Acad. V. M. Kotlyakova. 2006 .
West Siberian Plain
(West Siberian lowland), in the north of Eurasia, between the Kazakh hills and Altai in the south, the Urals in the west, the coast of the Kara Sea in the north and the Central Siberian plateau in the east. Almost entirely within Russia, partly in Kazakhstan. One of the greatest low-lying plains of the globe. Length from north to south approx. 2500 km, from west to east up to 1900 km; sq. OK. 3 million km². At the base of the deep A folded Paleozoic basement occurs at 1000–4000 m. On it is a cover of loose sedimentary rocks of the Mesozoic and Cenozoic, which contain fresh and mineralized, including hot, groundwater. It also contains colossal reserves of oil and natural gas, which are being developed in West Siberian oil and gas province. Most of the plain does not rise above 150 m above sea level. m., max. high (more than 300 m) are confined to the foothills of the Urals and Altai. To the center. parts of the plain in latitude extend Siberian Ridges(height up to 285 m). Parts with their own names stand out: relatively elevated "continents" - Belogorsk, Tobolsk; relatively lowered steppes - Ishim, Baraba; plains - Vasyugan and others. Significant ter. has an almost perfectly flat relief, especially within wide interfluves. In the north it is complicated by moraine hills and ridges, in the south by low parallel ridges. The climate is continental, subarctic in the north. Wed January temperatures vary depending on latitude from -28 to -16 ° C, July - from 4 to 22 ° C. Precipitation falls from 200 to 600 mm per year. All in. permafrost is common in the districts. Ch. river Ob, its tributaries drain most of the plain. Other rivers include the Pur and Taz in the north, and the left tributaries of the Yenisei in the east. there is an empty area. Up to 70% ter. the plains are swampy. Associated with this is the formation of numerous small lakes in the north, including those of thermokarst origin. Relatively large lakes are concentrated in the south (Chany, Ubinskoye, and others). On the West Siberian Plain, the law of latitudinal geographical zonality is classically expressed. The north belongs to the subarctic zone, dominated by landscapes of moss, lichen and shrub tundra. To the south it is replaced by a narrow strip of forest-tundra, beyond which begins the taiga of spruce, fir, cedar, pine and larch, which occupies most of the plain. The taiga is replaced by small-leaved forests of birch and aspen, then the forest-steppe begins with copses (chops), turning into the steppe. Southern districts in the main. plowed up. Nature is protected in the reserves: Verkhne-Tazovsky, Visimsky, Gydansky, Malaya Sosva, Central Siberian and Yugansky.
Geography. Modern illustrated encyclopedia. - M.: Rosman. Under the editorship of prof. A. P. Gorkina. 2006 .
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West Siberian Plain ... Wikipedia
Between the Urals in the west and the Central Siberian Plateau in the east. OK. 3 million km². The length from north to south is up to 2500 km, from west to east up to 1900 km. Height from 50 150 m in the northern and central parts to 300 m in the western, southern and ... ... Big Encyclopedic Dictionary
WESTERN SIBERIAN PLAIN, between the Urals in the west and the Central Siberian Plateau in the east. OK. 3 million km2. The length from north to south is up to 2500 km, from west to east up to 1900 km. Height from 50 150 m in the northern and central parts to 300 m in ... ... Russian history
Between the Urals in the west and the Central Siberian Plateau in the east About 3 million km2. The length from north to south is up to 2500 km, from west to east up to 1900 km. Height from 50 150 m in the northern and central parts to 300 m in the western, southern and eastern. ... ... encyclopedic Dictionary
The West Siberian Lowland is one of the largest low-lying accumulative plains in the world. It is located to the north of the low-hill plain of Kazakhstan and the Altai mountains, between the Urals in the west and the Central Siberian plateau in the east. Extending from N ... Great Soviet Encyclopedia
West Siberian Plain, West Siberian Lowland. One of the largest low-lying accumulative plains of the globe. It occupies most of Western Siberia, stretching from the coast of the Kara Sea in the north to the Kazakh uplands and ... Dictionary "Geography of Russia"
West Siberian Plain The West Siberian Lowland is one of the largest low-lying accumulative plains in the world. It is located north of the low-hill plain of Kazakhstan and the Altai mountains, between the Urals in the west and the Central Siberian plateau in the east. Extending from north to south up to 2500 km, from W. to E. from 1000 to 1900 km; an area of about 2.6 million sq. km 2. The surface is flat, slightly dissected, with small height amplitudes. The heights of the lowlands of the northern and central regions do not exceed 50-150 m, low elevations (up to 220-300 m) are characteristic mainly of the western, southern, and eastern margins of the plain. A strip of hills also forms the so-called. Siberian Ridges, stretching in the middle part of the Z.-S. R. from the Ob almost to the Yenisei. Wide, flat spaces of interfluves predominate everywhere, with slight slopes of the surface, heavily waterlogged and in places complicated by moraine hills and ridges (in the north) or by low sandy ridges (mainly in the south). Significant areas are occupied by flat ancient lake basins - woodlands. The river valleys form a relatively sparse network and in the upper reaches they are most often shallow hollows with poorly pronounced slopes. Only a few of the largest rivers flow in well-developed, deep (up to 50-80 m) valleys, with a steep right bank and a system of terraces on the left bank. Z.-S. R. formed within the epihercynian West Siberian plate, the basement of which is composed of intensely dislocated Paleozoic deposits. They are everywhere covered with a cover of loose marine and continental Meso-Cenozoic rocks (clays, sandstones, marls, etc.) with a total thickness of over 1000 m(in foundation depressions up to 3000-4000 m). The youngest Anthropogenic deposits in the south are alluvial and lacustrine, often covered by loess and loess-like loams; in the north - glacial, marine, and glacial-marine (capacity in places up to 200 m).
In the cover of loose deposits Z.-S. R. groundwater horizons are enclosed - fresh and mineralized (including brines), hot (up to 100-150 ° C) waters are also found (see West Siberian artesian basin). In the depths of Z.-S. R. the richest industrial deposits of oil and natural gas are enclosed (see the West Siberian oil and gas basin).
The climate is continental, quite severe. In winter, masses of cold continental air of temperate latitudes predominate over the plain, and in the warm season, an area of low pressure is formed and humid air masses from the North Atlantic often come here. The average annual temperatures are from -10.5°C in the north to 1-2°C in the south, the average temperatures in January are from -28 to -16°C, and in July from 4 to 22°C. The vegetation period in the extreme south reaches 175-180 days. The bulk of precipitation is brought by air masses from the west, mainly in July and August. Annual precipitation from 200-250 mm in tundra and steppe zones up to 500-600 mm in the forest zone. Snow cover thickness from 20-30 cm in the steppe up to 70-100 cm in the taiga of the Yenisei regions. The territory of the plain drains more than 2,000 rivers, the total length of which exceeds 250,000 km. km. The largest of them are the Ob, Yenisei, Irtysh. The main sources of river nutrition are melted snow water and summer-autumn rains; up to 70-80% of the annual runoff occurs in spring and summer. There are many lakes, the largest are Chany, Ubinskoye, and others. Some of the lakes in the southern regions are filled with salty and bitter-salty water. Large rivers are important navigable and rafting routes connecting the southern regions with the northern ones; The Yenisei, the Ob, the Irtysh, and the Tom have, in addition, large reserves of hydropower resources. The flatness of the relief Z. - S. r. determines a distinct latitudinal geographic zonality. A specific feature of most zones of Western Siberia is excessive soil moisture and, as a consequence, the wide distribution of marsh landscapes, which give way to solonetzes and solonchaks in the south. The north of the plain is a tundra zone, in which arctic, moss, and lichen landscapes form on arctic tundra and tundra gley soils, and in the south, shrub tundra. To the south there is a narrow strip of forest-tundra, where on peaty-gley, gley-podzolic and marsh soils complex landscape complexes of shrub tundra, spruce-larch woodlands, sphagnum and lowland bogs are developed. Most of the Z.-S. R. refers to the forest (forest-bog) zone, within which coniferous taiga prevails on podzolic soils, consisting of spruce, fir, cedar, pine, Siberian larch; only in the extreme south of the zone are taiga massifs replaced by a strip of small-leaved birch and aspen forests. The total forest area exceeds 60 million hectares. ha, wood reserves 9 billion. m 3, and its annual growth is 100 million. m 3. The forest zone is distinguished by the wide development of raised ridge-hollow sphagnum bogs, which in some places account for more than 50% of the area. Of the animals of the forest zone, the following are typical: brown bear, lynx, wolverine, marten, otter, Siberian weasel, sable, elk, Siberian roe deer, squirrel, chipmunk, muskrat, and other representatives of the fauna of the European-Siberian subregion of the Palearctic. To the south of the subzone of small-leaved forests, there is a forest-steppe zone, where leached and ordinary chernozems, meadow-chernozem, dark gray forest and marsh soils, solonetzes, solod . The extreme southern part of the Z. - S. p. It occupies the steppe zone, in the north of which until recently forb feather grass steppes predominated, and in the south - feather grass-fescue steppes. Now these steppes, with their fertile chernozem and dark chestnut soils, have been plowed up, and only areas with saline soils in places have retained their virgin character. Lit.: West Siberian lowland. Essay on nature, M., 1963; Western Siberia, M., 1963. N. I. Mikhashov.
Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .
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West Siberian Plain ... Wikipedia
Between the Urals in the west and the Central Siberian Plateau in the east. OK. 3 million km². The length from north to south is up to 2500 km, from west to east up to 1900 km. Height from 50 150 m in the northern and central parts to 300 m in the western, southern and ... ... Big Encyclopedic Dictionary
WESTERN SIBERIAN PLAIN, between the Urals in the west and the Central Siberian Plateau in the east. OK. 3 million km2. The length from north to south is up to 2500 km, from west to east up to 1900 km. Height from 50 150 m in the northern and central parts to 300 m in ... ... Russian history
One of the largest on earth. Takes b. h. Zap. Siberia, stretching from the coast of the Kara Sea in the north to the Kazakh uplands in the south, from the Urals in the west to the Central Siberian Plateau in the east. OK. 3 million km². Wide flat or ... Geographic Encyclopedia
Between the Urals in the west and the Central Siberian Plateau in the east About 3 million km2. The length from north to south is up to 2500 km, from west to east up to 1900 km. Height from 50 150 m in the northern and central parts to 300 m in the western, southern and eastern. ... ... encyclopedic Dictionary
West Siberian Plain- West Siberian Plain, West Siberian Lowland. One of the largest low-lying accumulative plains of the globe. It occupies most of Western Siberia, stretching from the coast of the Kara Sea in the north to the Kazakh uplands and ... Dictionary "Geography of Russia"