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East Sayan




East Sayan
The highest peak: The Munchu-Sardyk massif
Height of the top: 3491 m

The Eastern Sayan is a mountain system located within South Siberia, in the South of the Krasnoyarsk Territory, in the Irkutsk Region, in the western part of Buryatia and in the north-eastern part of Tyva. East Sayan begins on the left bank Yenisei, To the South-Zdeapa from Krasnoyarsk, and stretches more than 1000 km in a southeast direction almost to the coast Baikal.

Geological structure and mineral resources

Geologically, the Eastern Sayan represents an asymmetric folded structure of the northwest strike, adjacent to the southwestern edge of the Siberian Platform. By the age of the main folding, the Eastern Sayan is divided into 2 parts, separated by a deep fault zone: Late Precambrian (Riphean or Baikal) in the Northeast and Early Caledonian (Cambrian) in the Southwest. In the structure of the northeastern part, there are different ages of Precambrian: ortho- and paragneses, amphibolites, crystalline schists, green shales, marbles, quartzites, etc. Intrusions of Upper Riphean granitoids and ultrabasites also play a significant role. Precambrian rocks form a number of different blocks, separated by a system of deep and regional faults. The marginal blocks adjacent to the Siberian platform are part of its high raised fractured basement, which is involved in the zone of Baikal folding. They are separated from the rest of the East Sayan by the so-called Main fault, which in tectonic and metallogenic respect represents one of the most important structural parts of the Eastern Sayan.

East Sayan

In the structure of the Early Caledonian part of the Eastern Sayan, mainly the Lower Cambrian, partly Middle Cambrian volcanogenic-sedimentary formations and the Lower Paleozoic granitoid intrusions take part. All these rocks form a series of large blocks, delineated by faults. On the Precambrian and early Caledonian grounds of the Eastern Sayan, depressions began to form in the Devonian (Minusinsk, Rybin, and others) made by volcanic and gray-red sedimentary rocks of the Middle and Upper Paleozoic (from Devonian to Permian inclusive) and intrusions of alkaline granites and syenites of Devonian age. Since that time, as well as during almost the whole of the Mesozoic, the Eastern Sayan developed under the conditions of the continental regime, with the destruction of the ascending folded structure and general leveling of the relief occurring in most of the territory. In some Mesozoic basins mainly during the Middle Jurassic, terrigenous-carbonaceous deposits of considerable thickness accumulated. The main minerals are: mica (muscovite), associated with Upper Riphean pegmatites; Gold, confined to quartz, quartz-sulphide and quartz-carbonate veins; Graphite (Botogolsky Golets); Riphean ferruginous quartzites (Pine Bajt); Late Precambrian bauxites; Deposits of rare metals and rare earths associated with Upper Riphean pegmatites, Middle Paleozoic alkaline albitized granites and carbonatites; Asbestos, associated with ultrabasic rocks; Phosphorites in siliceous-carbonate rocks of the Early Caledonian part. In the South-East of the East Sayan, mainly in the Tunkinskaya depression, there are well-known mineral springs (Arshan, Nilova Pustyn and others).

East Sayan
Relief

The main directions of the largest ranges and chains of the Eastern Sayan coincide with the strike of the main tectonic structures and the most important faults. The general long-term alignment of the relief of the VS was interrupted in the Neogene by daisy-shaped uplifts, accompanied by differentiated motions of individual blocks. Accumulation of these movements, which created the modern mountain appearance of the Eastern Sayan at the end of the Neogene - anthropogen, was accompanied in the eastern part of the system by abundant outflow of basaltic lavas, widespread intensive erosion dismemberment and repeated glaciation of the highest elevated areas, which was mountain-valley and, in places, semi-human. In the western part of the East Sayan, the flat-topped ridges predominate, which, gradually rising in a southeasterly direction, form the so-called white mountains (Manskoe, Kanskoye and others) and "squirrels", which have received their name from snow patches that last for most of the year. In the upper reaches of the Kizir and Kazir rivers are the Agul Squirrels, which together with the Kryzhin Range and the Yergak-Targak-Taiga (Tazarama) Ridge, which form the western part of the western Sayan range, are forming the largest high-altitude node of the Eastern Sayan with almost Up to 3000 m and perfectly expressed Alpine forms of relief. The watershed Udinsky ridge departs from the same node, representing a high-mountain chain with sharply dissected relief. Further in the South-East the watershed ridges of the Eastern Sayan take on the character of flat-topped massifs, but the Alpine ridges (the Great Sayan ridge) again prevail to the east of the river Tissa, reaching the height in the mountain group Munku-Sardyk (3491 m) for the entire East Sayan. To the north of Munku-Sardyk, the high Kitoy and Tunkinsky Golts stretch almost parallel in the latitudinal direction, separated from the main ranges of the Eastern Sayan along the right bank of the Irkut by a system of intermontane depressions.

East Sayan

Along with the sharply dissected relief forms for the East Sayan, extensive areas of the ancient aligned relief are also typical, usually located at an altitude of 1800-2000 m to 2400-2500 m, in the eastern part, between the Khamsara and the Big Yenisei and the Upper Oka River basin, In the relief there are also hollow-sloping plateaus, composed of tuffs and lavas poured out of large shield volcanoes. In contrast to these volcanoes, which are already considerably destroyed by denudation, in East Sayan (the Oka river basin) Very young volcanic formations (volcanoes Kropotkin, Peretolchina, etc.) are very well preserved. For most of the slopes of mountain ranges located at an altitude below 2000 m, a typical average relief with deep cut valleys and relative heights up to 1000-1500 m is typical. From the bottom, a complex of these forms is surrounded by a hilly and low-mountainous relief of the foothills. In the intermontane basins (Tunkinskaya and others) and the lower reaches of the Kazyr and Kizir rivers, various types of accumulative relief are developed, formed by glacial, water-ice and lake sediments (hilly-morainic relief, terminal moraines, kamovye terraces, etc.).

East Sayan
Climate

The climate is sharply continental, with a prolonged and harsh winter, cool with unstable weather in summer, during which the bulk of precipitation falls. The continentality of the climate increases from West to East. At altitudes of 900-1300 m, the average January temperature ranges from -17 to -25 ° С, July - from 12 to 14 ° С. The distribution of precipitation is closely related to the orientation of the mountain slopes: on the western and south-western slopes, open to the side of moist ear streams, they drop to 800 mm and more per year, in the northern foothills to 400 mm, and in the eastern and south- Eastern areas, located in the "rain shadow" - no more than 300 mm. Winter in the West is snowy, in the East there is little snow; In the eastern part, the strata of permafrost are widely distributed. In the highest ranges - the eastern part of the Kryzhina Range, the Topografov Peak (the largest center), Munku-Sardyk - there are modern, mainly carr glaciers. It is known about 100 small glaciers with a total area of ​​about 30 km2.

East Sayan
Types of landscapes

The main types of landscapes of the Eastern Sayan are mountain-taiga and highland. Only in the foothills (up to the height of 800-1000 m) and in the Tunkinskaya basin there is a predominance of bright larch and pine forests alternating with forest-steppe and meadow-hollow (along the Irkut river valley) plots. Typical mountain taiga landscapes occupying more than 50% of the area of ​​the Eastern Sayan are developed on the slopes of all major ridges and in river valleys. The mountain-taiga belt is characterized by a moderately cool and fairly humid (especially in the West) climate. Dark coniferous taiga spruce-cedar-fir forests prevail on mountain taiga weakly podzolic light deep-alkaline soils, rising in the West and in the central part to an altitude of 1500-1800 m, and lighter larch-cedar forests on mountain-frozen-taiga humus-podzolized, and also Acid ferruginous soils, forming in the East and South-East the upper boundary of the forest at an altitude of 2000-2250 m. Mountain-taiga forests are the main habitat of the most important representatives of the animal world, many of which are fishermen and. Here live: squirrel, hare, fox, roe deer, maral, moose, brown bear and others; From birds - hazel grouse, wood grouse, woodpeckers, nutcrackers, etc. Sable and musk deer occur at the upper boundary of the forest and among the rocks. Highland landscapes are characterized by a harsh climate, prolonged and cold winters, short and cool summers, intensive solifluction and physical weathering processes. On the leveled watersheds dominates the shrub and moss-lichen rocky tundra on low-power mountain-tundra soils; In the western, more humid part of the Sayan, along with the mountain tundra, subalpine shrubs and meadows are often developed, sometimes high grass. Strongly dissected slopes and peaks of the Alpine mountains represent a stony desert, almost devoid of vegetation. Stone scree and kurum are widely used.




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