Geology, geography and global energy

Scientific and Technical Journal

Sulfate karst: special features

2012. №4, pp. 198-208

Golovachev Ilya V. - C.Sc. in Geography, Astrakhan State University, Astrakhan department of Russian geographical society, 16 Tatishcev st., Astrakhan, Russian Federation, 414025, bask_speleo@mail.ru

Khvoroshch Aleksey B. - Research assistant, Russian Academy of Sciences, , 1g Prostornaya st., Krasnodar reg., Gelendzhik, Russian Federation, 353467, orso@land.ru

Bystrova Inna V. - C.Sc. in Geology and Mineralogy, Associate Professor, Astrakhan State University, 20a Tatishchev st., Astrakhan, Russian Federation, 414000, geologi2007@yandex.ru

Almamedov Yalchin L. O. - Post-graduate student, Astrakhan State University, 20a Tatishchev st., Astrakhan, Russian Federation, 414056, geologi2007@yandex.ru

This article analyzes the work of various researchers on the characteristic features of sulfate karst. Lithologic types of karst-released sulfate karst are generally characterized by high activity. Subsequently, the paper deals with the high density of karst, its morphometric parameters, and the vast number of karst holes. Two types of karst-related materials – anhydrite and gypsum – have been widely covered by many well-known domestic researchers. Nonetheless, the study gives an overview on the features of karst gypsum and anhydrite to better explain the specifics of sulfate karst taking place in the North Caspian Sea (where it is associated with keprokov salt dome sites found on the waterway’s surface). Historically, sulfate Karst develops according to the same laws as carbonate karst. However, it has a number of distinctive features which can be noticed in the physical and chemical properties of gypsum and anhydrite. First of all it exhibits water solubility. The solubility of CaSO4 in distilled water at t = 0? C is 1.759 g/L, while at t = +40? C it is 2.093 g/L. Moreover, the solubility of anhydrite at t ^+42? C is higher than that of plaster. But at higher temperatures, the opposite case – lower solubility – occurs. AM Kuznetsov, in his report, investigated the rate of dissolution of gypsum in water, finding that anhydrite gypsum dissolves more rapidly. He also noted that dissolution decreases during the saturation of water with calcium sulfate. An alternative study by KA Gorbunova, noted the solubility of calcium sulfate. He observed how the nature of the mineral compound was influenced during its interaction with rock and water. Gorbunova also paid attention, inter alia, to the compound’s temperature, the presence of impurities, the ratio of gypsum and anhydrite in the rock, the velocity of the solvent, and the solvent’s presence in other salts.

Key words: sulfate karst,special features of sulfate karst,karst of gypsums and anhydrite,hydration of anhydrite,salt cupolas,gypsum cap rocks,northern section of Caspian region

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