STRUCTURAL–LITHOLOGICAL AND ORE–BEARING CHARACTERISTICS OF THE MIDDLE HORIZON OF THE NOVOPETRIVSKA SUITE WITHIN THE NORTH PART OF THE TARASIVSKE DEPOSIT

Abstract

The Tarasivske deposit is distinguished by the polymineral composition of its ore sands, which makes it a strategic source not only of titanium and zirconium but also of rare elements. The article presents historical aspects of the study of the Tarasivske deposit and provides a brief description of its geological structure. The main focus is placed on the deposits of the Novopetrivska Suite of the Poltava Series (Neogene), particularly on its middle horizon, which contains the principal reserves of titanium-zirconium minerals. The analysis of the structural-textural features of the sands of the Novopetrivska Suite made it possible to refine the facies and hydrodynamic conditions of formation of its lower, middle, and upper horizons. The formation of the deposits of the Novopetrivska Suite occurred during a transgressive–regressive stage of the geological development of the territory, which determined the change of facies conditions from alluvial-deltaic to shallow-lagoonal and finally to alluvial. Sedimentation in Novopetrivska time took place under predominantly low-energy and stable hydrodynamic conditions, but with short-term high-energy impulses. Based on coordinates, descriptions, and borehole sampling results, a set of maps was created that reflects the relief of the base and roof, the thickness of productive deposits, and the lateral distribution of the average contents of ilmenite, rutile, zircon, kyanite+sillimanite, monazite+cassiterite, and chromite  within the north part of the deposit. The cartographic constructions made it possible to clarify the features of the structural and material parameters of ore–bearing capacity of the middle horizon of the Novopetrivska Suite. In particular, it was established that the relief of the base and surface is uneven, with local depressions and elevations. The amplitude of their absolute elevation differences reaches up to 52 m. Within the area, local depressions in the base relief were identified, where the thickness of productive deposits increases to 30–51.2 m. The highest average contents of ilmenite, rutile, zircon, and collective concentrate are localized in the southwestern, western, and northeastern parts of the area. Using correlation analysis, the direction and strength of relationships between the average content of individual minerals in boreholes and the structural parameters of productive deposits were determined. It was found that all correlations between the average mineral content are direct and mostly strong or moderate. The main core of strong correlations is formed by ilmenite, rutile, and zircon. An investigation was conducted into the distribution of mineral content and the correlation relationships among them within the vertical profiles of boreholes