GEOLOGICAL STRUCTURE AND ORE-BEARING OF THE YURSKA AREA OF THE MEZHYRICHNЕ TITANIUM ORE DEPOSIT
Authors: Figura L.A. , Kovalchuk M.S. 
Published: December 2023

Information on the geological structure of the Yurska area of the Mezhyrichnе titanium ore deposit is provided. It was found out that the geological structure of the site involves crystalline rocks of the foundation, their weathered crust and continental and marine deposits of different ages of the Mesozoic and Cenozoic: Lower Cretaceous continental (Irshan suite), Upper Cretaceous coastal marine (Moshno-Rudnyan suite), Paleogene (marine and continental), Neogene and Quaternary continental sediments. A useful mineral of the Jurassic area is ilmenite, which forms ore bodies in the crust of weathering of crystalline rocks of the foundation, sediments formed due to erosion and redeposition of eluvium (Irshan suite), as well as in rocks formed due to erosion of secondary ilmenite reservoirs (Moshno-Rudnyan suite and, to a lesser extent, heterogeneous genetic formations of the Quaternary system). The maximum content of ilmenite in the weathering crust is 430.2 kg/m3; in fluvial kaolins of the Irshan suite — 1447.4 kg/m3; in differently-grained sands of this suite — 506.2 kg/m3; in the sandy-siliceous horizon of the Moshno-Rudnyan suite — 256.7 kg/m3; in Quaternary loams and sandy loams — 146.4 kg/m3. The industrial placers of ilmenite are localized in the formations of the Irshan suite. Sandy-siliceous rocks of the Moshno-Rudnyan suite with an ilmenite content of more than 15 kg/m3 are included in the composition of the upper part of the industrial placer layer. On the basis of the coordinates, description and testing of the 1613 wells, a target database was created, on the basis of which a set of maps was built: maps of the lateral distribution of the average ilmenite content in the gruss of zone dezintegration of weathering rocks, in the kaolins of eluvial, in the fluvial kaolins and sands of the Irshan suite, and in the sandy-siliceous rocks of the Moshno-Rudnyan suite; maps of bottom and top surface relief and thickness of kaolins and sands of the Irshan suite and sandy-siliceous rocks of the Moshno-Rudnyan suite. The structural (nature of the relief of the bottom and top surfaces of ore-bearing deposits and their thickness) and material (lithological composition, distribution of ilmenite along the lateral and in the vertical cross-section of ore-bearing deposits) of placers parameters were studied. It was found that the relief of the bottom and of the top of the ore-bearing formations is uneven with local elevations and depressions. It was found that the content of ilmenite in the weathering crust increases, as a rule, up the section from the zone of disintegration and leaching to the zone of final hydrolysis and oxidation of weathering products. The vertical distribution of ilmenite in the Irshan and Moshno-Rudnyan rocks is uneven with a general tendency to decrease upwards along the section. Sometimes there are several enrichment horizons of insignificant thickness, or a significant content of ilmenite is present in the top of the rocks. Sometimes there are several enrichment horizons in the rocks, as a rule, in the lower and upper parts of the geological section. The directionality and strength of correlations between the relief of the sole and the surface, thickness and average content of ilmenite in ore-bearing rocks of different-ages and different-genetics of the Cretaceous system were investigated. It was found that the correlations have different directions and are mostly very weak, weak, sometimes moderate, medium and rarely strong. It was established that the distribution and content of ilmenite in the weathering crust is determined by its distribution and content in the crystalline rocks of the foundation. The distribution and content of ilmenite in the continental fluvial formations of the Irshan suite is determined mainly by the facies conditions of sedimentation and is rarely determined by its significant content in the underlying rocks. The distribution of ilmenite in the formations of the Moshno-Rudnyan suite is determined by the facies conditions of formation, and its content is determined by its content in the underlying rocks.