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Western Sayan

Western Sayan
The highest peak: Kyzyl-Taiga
Height of the top: 3121 m

The Western Sayan is a mountain system located within the Southern Siberia, in the South of the Krasnoyarsk Territory and the North of Tyva. The Western Sayan begins in the upper reaches of the Maly Abakan River (east of Teletskoye Lake) and stretches to the Northeast a distance of about 600 km to the junction with East Sayan In the sources of the rivers Kazir and Uda.

Geological structure and mineral resources

The folded structure of the Western Sayan has a northeasterly strike and forms the interior of the Altai-Sayan folded region. It was formed in the era of Caledonian folding (in the Silurian). From the North, the East and the South, it is surrounded by Salair (Cambrian) structures, which also form a narrow strip of the northern slope of the Western Sayan. Here, the deposits of the lower and middle Cambrian are widely distributed: spilites, porphyrites, siliceous shales, tuffs, tuffites, graywacke sandstones, reef limestones, broken by granitoids. The Lower Cambrian formations are unconformably overlain by a thicker conglomerate and sandstone of the Upper Cambrian. Reddish-red alkanoic rocks of the Devonian are of limited distribution.

Western Sayan

The main (Caledonian) structure of the Western Sayan is formed by two marginal anticlinoria and synclinorium between them. The anticlinoria are composed of lower- and partly Middle Cambrian metamorphosed clayey, siliceous schists, greenstone effusives, quartzites, and limestones. The rocks are broken by small bodies of hyperbasites. In the northern (Jebash) anticlinorium, the tectonic block among the Cambrian deposits is composed of Precambrian metamorphic schists. Less prevalent in the anticlinoria are incoherently lying Upper Cambrian clastic rocks, Silurian terrigenous-carbonate and Devonian red-carbon-alkaline rocks that perform overlapping depressions. The synclinorium is composed of a continuous (up to 15 km) continuous sandy-slate series of the upper (part and middle) Cambrian, Ordovician and, possibly, the Lower Silurian. The series consists of fine-grained terrigenous rocks, which are replaced by terrigenous-carbonate sediments of the Silurian. Devon red, as well as Carboniferous terrigenous rocks perform superimposed depressions. The Devonian includes the introduction of large massifs of granitoids. A large role in the structure of the Western Sayan belongs to the faults. Minerals are confined to the marginal parts of the Western Sayan. The Cambrian intrusion of the northern slope involves deposits of iron and copper-cobalt ores. Ores of gold, nickel, chromium, asbestos deposits are associated with marginal anticlinoria, in particular with ophiolite belts. Devonian granitoids are associated with ore occurrences of silver, molybdenum, lead, zinc.

Western Sayan

The Western Sayan is a system of comparatively narrow flat and pointed ridges, separated by a dense river network belonging to the Yenisei basin. In the central part of Western Sayan, it abruptly breaks off to the vast Minusinsk depression in the North (see Minusinsk depression), and at the foot of its southern slopes is the vast Tuva basin. On the southern slope of the Western Sayan, between the ridges Mirsky and Kurtushibinsky, is Usinsk, and at the foot of the southern slope of the Kurtushibinsky ridge is the Turano-Uyuk basin. The modern mountainous terrain of the Western Sayan was formed as a result of the daisy-like uplifts of the Neogene end - the beginning of the anthropogen, accompanied by differentiated movements of individual blocks, intensive erosion dismemberment and repeated glaciation of the highest elevated ridges, which were predominantly mountain-valley. Extensive areas of the ancient, leveled relief in the Western Sayan remained little, which is explained by the more dense and deep dismemberment of the mountain system by the valleys of the tributaries of the Yenisei. The main (watershed) range of Western Sayan in its western part (up to the deep-cut Yenisei valley) is characterized by a typical alpine relief from an altitude of 2800-3000 m. To the South is the highest point of the Western Sayan-Kyzyl-Taiga (3121 m), and The base of its crest part is the high-raised (1500-2000 m) Alash plateau, steeply cutting off to the valley of the river Khemchik. Along the right bank of the Alash River, a separate Ba-Taiga massif (altitude 3129 m) rises, which is also included in the Western Sayan system by individual researchers. To the east of the Yenisei valley, the height of the watershed ridge is reduced to almost 2000 m (maximum 2263 m) and the relief is mostly of medium-scale nature (the central parts of the Oi ridge with the adjacent Aradan ridge and the Ergaki ridge with the Alpine relief are excluded). In the western part of the watershed ridge there are two branches: the northeastern (the ridges of Kantegir, Sabinsky, Jebash and Borus) and the southeastern (Khemchik and Kurtushibinsky ranges). At the western extremity of the Oi ridge (north-eastern branch) and the eastern extremity of the Ergaki ridge (south-eastern branch), these branches again approach the main watershed. From the sources of the Us and Amyl rivers, the height of the main watershed (called here Ergak-Targak-Taiga or Tazarama) is gradually increasing, reaching almost 3000 m at the junction with the East Sayan system. Most of the side ridges, with a height of 2000-2500 m, have a typical mid-range appearance.

Western Sayan

The climate is sharply continental, with a long and cold winter, short and cool (in the mountains) in summer. On the northern and southern slopes of West Sayan at an altitude of 1000-1400 m, the average January temperature is -20 to -25 ° C, in intermountain hollows to -30 ° C. Summer in the mountains, especially in the highlands, is characterized by unstable weather and low temperatures (the average July temperature is 10-12 ° C); In the intermontane basins it is warm (the average temperature in July is up to 20 ° C). Precipitation falls mainly in summer. The number of them varies greatly depending on the altitude of the terrain and the orientation of the slopes from 400-500 mm per year in the northern foothills to 1000-1200 mm on the northern slopes open towards the humid air currents; On the southern slopes that are in the "rain shadow" and in the intermountain hollows, their number is 400-500 mm and 300-350 mm, respectively. Modern glaciers in the Western Sayan are unknown, but many snowflakes persist throughout the summer and the thickness of firn in places occupy significant areas.

Western Sayan
Types of landscapes

The main types of landscapes are: mountain-taked, occupying almost all northern slopes and the upper part of the southern slopes of Western Sayan; Mountain forest-steppe, especially characteristic for the southern slopes of ridges; Alpine, confined to the top parts of ridges, rising above the forest boundary. In the north of the Western Sayan there is a strip of landscapes of pine-birch forest-steppe of the Minusinsk depression, which are replaced in the foothills by a belt of light coniferous (larch) and deciduous (from birch and aspen) forests on mountain gray forest, less sod-podzolic soils. At altitudes from 800-900 m to 1500-1800 m on the northern slopes of ridges, which usually have a typical mid-range appearance, dark coniferous taiga predominates from cedar, fir and spruce (the latter mainly along the river valleys) with a continuous moss cover on the mountain- Taiga soils. At the upper border, the taiga forests gradually thin out and pass into cedar and larch woodlands. Most of the slopes facing the Tuva basin are mountainous forest-steppe landscapes: on the slopes of the southern exposition on the chestnut soils mountain steppes are developed, and on the slopes of the northern exposition - light larch park forests on gray forest, poorly podzolized soils. Only in the middle part of the southern macroslope of the Western Sayan there appear continuous light coniferous larch forests, which are replaced later by a strip of cedar-larch and cedar forests on mountain-taiga soils, rising to an altitude of 2000-2200 m. Thus, for the southern slopes of the Western Sayan is no longer "Siberian ", And a transition to the" Central Asian "type of high-altitude zone of landscapes.

Western Sayan

Differences in the landscape affect the composition of animals that live on the northern and southern slopes of Western Sayan. On the northern slopes are common protein, hare-rabbit, fox, columns, roe deer, maral, elk, brown bear, and from the birds - hazel grouse, wood grouse, woodpeckers, nutcrackers, etc .; On the southern slopes, except for them, many steppe species (long-tailed ground squirrel, steppe horse, field harrier and many others) are found that are absent in the dark coniferous taiga. In the intermontane basins, the number of steppe species considerably increases. Highland landscapes are less diverse. They are characterized by harsh climatic conditions, long and cold winters, short and cold summers. Along with different variants of the mountain tundra that prevails in the aligned areas, thickets of bushes, alpine and subalpine meadows are developed on the mountain meadow soils in the West Sayan, alternating with stone placers and kurums, often almost completely devoid of vegetation. The animal world consists of both high-altitude species (Altai pika, white and tundra partridge, etc.) and those from the mountain-taiga zone (chipmunk, ermine, columns, weasel, sable, brown bear, elk, etc.).

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