Rishtan and Kyzyl-Dzharskoye Deposits
Rishtan Deposit is located 15 km south of the city of Rishtan in Uzbekistan and 20 km east of the river Sokh. The mineral springs are associated with the limestones of the Alai and Turkestan strata, which lie in the core of the local anticlinal fold. The water has a mineralization of 3-6 g/l, a chloride-sulfate calcium-sodium composition, and contains 50-110 mg/l of total hydrogen sulfide. The flow rate of the Rishtan springs exceeds 4 l/s, which is sufficient to provide water for a medical facility offering about 1,000 bath procedures per day; currently, there is a local balneotherapy center visited by residents of the nearby settlements.
Kyzyl-Djar Deposit is located near the settlement of the same name in the Jangi-Jol district of the Osh region. The mineral waters are classified as strong sulfide bicarbonate-chloride sodium of medium mineralization type "Old Matsesta"; a distinctive and very valuable feature of these waters is their content of 40-50 nCi/l of radon, which allows them to be classified as strong sulfide medium-radon types, of great interest for balneology.
Groundwater with a distinct hydrogen sulfide smell (with concentrations in analyses ranging from 3-8 mg/l, i.e., below the lower limit necessary to classify the water as sulfide) is often found among low-mineralized nitrogen thermal waters in the mountainous part of the republic. The presence of this gas somewhat increases the balneological activity of the waters but does not determine it. Since there are no necessary conditions for the generation of hydrogen sulfide due to biochemical sulfate reduction— the most common process for the formation of sulfide waters— hydrocarbons are absent here; the main process in these conditions is accepted to be the decomposition of sulfides by superheated steam or superheated water at a certain depth below the surface. The presence of hydrogen sulfide in this case indicates the relative proximity of the zone of superheated waters and the possibility of their extraction to the surface through relatively shallow wells at several hundred or the first thousand meters.
