Siumar N. Lithological peculiarities of Upper Devonian (Frasnian) and Cisuralian salt formations of Dnipro-Donets depression

The results of previous studies involving the new data of drilling traditional methods are generalized and new approaches, in particular, geographic information technologies for better establishment of occurrence areas and Upper Devonian (Frasnian) and Cisuralian (Lower Permian) salt formations distribution properties are used. The maps of the structural surfaces on geological material are generated, the results on the degree of reliability are analyzed, and the correlation between the depth and thickness of Upper Devonian (Frasnian) and Cisuralian salt formations is performed. Ground water within the researched area is characterized by considerable variability of salinity, macro-and microcomponents content. Specific peculiarity of this sequence is the presence of thick strata of the Cisuralian and Upper Devoniant saltbearing rock mass. On determining this hydrochemical "anomalies" formation mechanisms the evaluation of ground water dynamics and orientation of physical-chemical processes in the "rock-water" system is of fundamental importance. In this regard, maps of salinity izopahits, Na/Cl relations and other hydrological characteristics of groundwater has been created. Based on analysis of lithological and paleohydrological data maps the conditions of groundwater chemical composition in area and in the context has been determined as different. Strontium isotope composition has been measured in samples of anhydrite from central and south eastern parts of the Mykytiv and Slovyansk subformations of the Cisuralian salt formation (Kopylovska, Ryabuhinska, West Spivakovska areas) and in 1 sample from the Upper Devonian (Frasnian) salt formation (Chutivska structure). The measured isotope composition ratios 87Sr/86Sr vary from 0.70779 to 0.70810. The figures are consistent with the Lower Permian part of the oceanic srontium isotope curve in the Phanerozoic. 87Sr / 86Sr values of the anhydrite of the Mykytiv subformations are 0.70781 and 0.70792; those from Slovyansk: 0.70779 - 0.70810. The highest value measured in anhydrite from West Spivakovka area (Slovyansk subformation) can be explained by the continental influence, as evidenced by the presence of terrigenous layers in the section.