Evaporites of Ukraine: a review

Abstract

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.

Salt geology and mining traditions: Kalush and Stebnyk mines (Fore-Carpathian region, Ukraine)

“…These salt-bearing deposits differ in the thickness and lithology depending on the regional tectonic location (Czapowski et al, 2009). In the Ukrainian part of Carpathian Foredeep, three main tectonic zones were distinguished (Figs 1, 2): (I) outer zone (Bilche-Volytsya Unit), in which the Miocene molasse deposits overlie discordantly the Mesozoic platform basement at the depth of 10-200 m, and in the foredeep they subsided under the overthrust of the Sambir zone and are at depths of 1.2-2.2 km (Hryniv et al, 2007); (II) central zone (Sambir Unit), in which the Miocene deposits were overthrusted onto the external part of the Foredeep on the distance of 8-12 km and the deposits of the external zone occur at the depth of 1.0-2.2 km; (III) internal zone (Boryslav-Pokuttya Unit), in which the Miocene deposits were overthrusted onto the Sambir Nappe zone on the distance of 25 km (Hryniv et al, 2007).…”

“…Two main evaporite formations (ukr. svity; Hryniv et al, 2007;Petryczenko et al, 1994), occur: (I) Vorotyshcha Beds, dated as Late Eggenburgian and Ottnangian, 1.1-2.3 km thick, is composed of clays with sandstones, rock and potash salt interbeds (Petryczenko et al, 1994;AndreyevaGrigorovich et al, 2008). This suite was subdivided into two parts (subsuites): the lower one 100-900 m thick with rock salt beds and the upper one 0.7-1.0 km thick with beds of potash salts (Hryniv et al, 2007).…”

“…svity; Hryniv et al, 2007;Petryczenko et al, 1994), occur: (I) Vorotyshcha Beds, dated as Late Eggenburgian and Ottnangian, 1.1-2.3 km thick, is composed of clays with sandstones, rock and potash salt interbeds (Petryczenko et al, 1994;AndreyevaGrigorovich et al, 2008). This suite was subdivided into two parts (subsuites): the lower one 100-900 m thick with rock salt beds and the upper one 0.7-1.0 km thick with beds of potash salts (Hryniv et al, 2007). In the latter subsuite, in the area of Boryslav-Pokuttya Nappe, close to the Carpathian overthrust, the large Stebnyk rock and potash salt deposit occurs ( Figs 1-3); (II) Tyras Beds of Badenian age attains the thickness of 300-800 m in the Sambir Unit and consists of salt breccias and rock and potash salts.…”

“…In the BilcheVolytsya Unit deposits varies from 20-70 m and contains claystones, sandstones, carbonates, sulphates and rock salts. Distribution of potash and rock salt deposits (red areas, salt mines marked) in background of regional geological structure of western Ukraine (after Hryniv et al, 2007). The salt-works existed directly before the World War II also indicated (after Windakiewicz, 1939) • Rozmieszczenie złóż soli potasowych i kamiennych na tle geologii regionalnej zachodniej Ukrainy (wg Hryniv et al, 2007).…”

“…Salt-bearing deposits were traditionally attributed to two main rock complexes (Lower and Upper Vorotyshcha Beds) separated by terrigenous (sandstones and conglomerates) Zahirsk Beds (Petryczenko et al, 1994). Several papers of last years indicated that Zahirsk Beds belonged to the olistostrome horizon (submarine slump, interrupting evaporite deposition) and there were no arguments for subdividing the Vorotyshcha Beds into two subunits (Hryniv et al, 2007).…”