Amudarya artesian basin
AMUDARYA ARTESIAN BASIN (RU: Амударьинский артезианский бассейн) occupies the depression of the same name within the limits of the Uzbek SSR and Tajik SSR. The top level of the basin is represented by the continental, rarely marine Quaternary, Neogene, and Upper Paleogene formations (pebbles, conglomerates, gravel, sand, sandstones, clayish formations, less often limestones) with the thickness of up to 600 metres. The underground waters are not pressurized and weakly pressurized, of the variegated composition, with mineralization of up to 100 grams per litre. The specific yields of the drilled wells are up to 1 litres per second, the total yield is up to 10, less often up to 25 litres per second; the coefficient of the filtration (Cf) is approximately 10, less often 20-30 metres per day. They are fed by the atmospheric precipitation, by the surface waters.
The middle level is separated from the upper one by the clays of Eocene-Oligocene, and is represented by the marine, lagoon, and continental (limestones, marls, sandstones, aleurolites (siltstones) with lenses, layers of clays and salts) depositions of Paleogene and Mesozoic (of the total thickness of up to 4500 metres). The yields of the drilled wells are up to 25 litres per second, Cf is up to 10 metres per day, the waters are pressurized, the mineralization varies from 1-3 to 150-200, even up to 550 grams per litre within the salt-gypsum formation of Jurassic; the chemical composition is from the bicarbonate-sulphate ones to the typical sodium chloride ones. The brines contain H2S, I, Br, B.
The bottom level is represented by the Paleozoic and pre-Paleozoic sandstones, schists, limestones, and igneous rocks. There have the practical significance the fresh waters of the carbonatic rocks and of the zones of the crushing of the tectonic faults, where the yields of the springs are up to 5 litres per second, of the drilled wells are up to 10 litres per second.
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