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Regional reviews |
Institute of Geology and Geochemistry of Combustible Minerals, National Academy of Sciences of Ukraine, Naukova 3A, 79053 Lviv, Ukraine (e-mail: Sophia_Hryniv{at}ukr.net, igggk{at}ah.ipm.lviv.ua)
The results of geological and lithological–geochemical investigations of the Devonian, Permian, Jurassic and Miocene evaporite deposits of Ukraine are presented in review. The main regions of evaporite distribution are the Dnipro–Donets depression, Carpathian (Forecarpathians, Transcarpathians) and Foredobrogean regions. The data on tectonics and stratigraphy are presented and information on lithology, the mineralogical and geochemical study of gypsum, anhydrite, rock and potash salts are summarized. The rich mineral composition of the Miocene evaporites in the Carpathian Foredeep (more than 20 salt minerals) is demonstrated, and the unique superimposed hydrothermal mineralization in the rock salt of salt domes from the Dnipro–Donets depression is presented (containing about 40 high- and mid-temperature hydrothermal minerals). In particular, the results of brine inclusion studies in evaporite minerals suggest that seawater was the main source of most of the salts. The brines in both the Miocene and Permian evaporite basins are classified as the Na–K–Mg–Cl–SO4 (SO4-rich) chemical type and the Jurassic and Devonian belong to the Na–K–Mg–Ca–Cl (Ca-rich) type. Temperature of solutions during halite precipitation shifted from 25 to 43 °C, while during the stage of potash salt sedimentation it apparently increased to 40–83 °C.
