Volga-Kama artesian basin
VOLGA-KAMA ARTESIAN BASIN (RU: Волго-Камский артезианский бассейн) is situated at the east of the European part of the USSR (the Bashkir ASSR, the Tatar ASSR, and the Gorky, Kirov, Kuibyshev, partly Perm and Orenburg provinces of the Russian Federation). The area is more than 800 thousand square kilometres. The basin is confined to the eastern part of the Russian tectonic plate, and to the Urals foredeep. The basin is bounded at the east by the western slope of the Ural mountains, and at the north by the drainage divide between the systems of the drainage of the Caspian sea, and of the White sea and Barents sea; at the west, along the system of the embankments, the basin borders on the Moscow basin and Sura-Hoper basin; at the south, along the system of the flexures and dip-slip faults, the basin borders on the Caspian basin.
The major aquifer systems of the basin are the carbonate and carbonate-terrigenous depositions of the Permian, Carboniferous, and Devonian ages. The maximal thickness of the sedimentary depositions is up to 10 kilometres (the Urals foredeep). There are characterized by the greatest water saturation the carbonate depositions of the cross-section (limestones, dolomites, marls), which are embedded at the depth of up to 200-300 metres; the yields of the boreholes in case of the free flow vary from 1.0 to 10-15 litres per second, the water conductivity varies from 300-800 to 3000-5000 square metres per day. At the great depths (up to 1500 metres and more), the yield is from 1.0-5.0 to 2500-4000 cubic metres per second, the water conductivity is up to 10 square metres per day. The composition of the waters up to the depth of 250 metres, HCO3- and SO42--HCO3-, the mineralization is up to 1.0 grams per litre (at the places with the distribution of the gypsum, SO42- and SO42--Cl-, 1.5-3.0 grams per litre); at the depth of more than 350-400 metres, Cl--Na+, 20-80 grams per litre; at the depth of 600-1000 metres and more, the brines, which are containing I, Br. The temperature of the underground waters varies from 2-4 to 50 degrees Celsius and more (at the depth of more than 2000 metres).
The major regions of the supply are confined to the outcrops of the Paleozoic depositions on the western slope of the Ural mountains, and to the structural uplifts of the eastern part of the Russian tectonic plate. The discharge of the underground waters is performed through the water sources, through the filtration and overflowing into the overlying horizons, and through the boreholes. There are associated with the aquifer systems of the Paleozoic depositions within the basin the petroleum and gas-petroleum fields (see the "Volga-Ural petroliferous province" article). The underground waters are used for the water-household supply, during the operation of the gas-petroleum fields, and so on.
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