Natural factors forming the quality of carbonate raw materials
Authors: Repina K. V. 
Published: January 2019

The article is devoted to the study of natural factors that influence the regularities in the distribution of the quality of carbonate raw materials in the deposits of the Articulation Zone of the Donbass Basin with the Priazovskiy block of the Ukrainian Shield. Paleogeographic conditions of sedimentation and the processes of secondary quality change were established by comparing the lithologic-stratigraphic sections of deposits in different parts of the Articulation Zone: from the west (Novotroitskoe deposit) through the center (Elenovskoe deposit) and to the east (Karakubskoe deposit). The variability in the quality of carbonate raw materials was estimated from the results of statistical processing of the chemical analysis of exploratory samples. Geochemical associations were established for carbonate rocks within the stratigraphic horizons of each deposit. The best in quality of all deposits of the Donbass Articulation Zone are the carbonate rocks of the Cl t c horizon. The conditions for their formation were the most stable. They are characterized by a negative connection of the main quality component (CaO) with all other quality indicators. At the same time, the association of indicators associated with a significant positive connection is retained: SiO2, R2O3, S.The process of forming carbonate strata are accompanied by intense silicification processes that relate to climatic changes in temperature, salinity and depth of the sea basin. This is confirmed statistically, because the significant negative correlation between the main component of quality and silica is established on the horizons of carbonate rocks with an increased silica content. The process of dolomitization of the carbonate stratum took place in two stages. At the beginning of the accumulation of the carbonate layer, the sea basin was characterized by lower temperatures and higher magnesium contents than in the subsequent period. Therefore, the lower stratum of the Novotroitskoe and Elenovskoe deposits include sedimentary dolomites. Later, the conditions changed, so there are no dolomites in the Karakubskoe deposit. The second stage of dolomitization is associated with the post-carbon andesite-trachyandesite magmatic complex. The rocks of this complex are found in the carbonate stratum in the form of interplastic intrusions, dikes and stock-like bodies. This contributed to the appearance of sulphide mineralization, zones of silicification and recrystallization of carbonate minerals in spot-dolomitized limestones. The structural-tectonic factor, which is manifested by intensive leaching processes, exerts the greatest influence on the degradation of the quality of carbonate raw materials. In zones of tectonic disturbances, they have maximum extension areas. The structural transformationsthat began in the Donbas after the early Carboniferous disrupted the primary stratified occurrence and quality of the carbonate thickness. The upper Visean horizons are subject to intensively leached, similar to tectonic,melange.The contribution made by these studies to scientific knowledge lies in the identification of the natural factors that determined not only the quality of carbonate rocks, but also indicators of the development stages of the Donbass Articulation Zone of two major tectonic structures - Donbass and the Ukrainian Shield. The practical significance of the results of the work is connected with the fixed possibility of conducting geological and technological mapping and further construction of varietal maps of the deposits of carbonate raw materials.