Yaremenko O. Geological conditions of formation and development of the Torchyn deposit of the apatite-ilmenite ore of the Ukrainian shield.

Dissertation is for the degree of candidate of geological sciences, specialty 04.00.01 – general and regional geology. – Institute of Geological Sciences of the National Academy of Sciences of Ukraine, Kyiv, 2020. In the dissertation the peculiarities of geological structure of Torchyn residual ilmenite deposit developed on the layered gabbroid body, are examined. On the deposit the lower and central zone of the body go to the erosion truncation that is reflected in the ilmenite and titaniferous magnetite distribution. The presence of differentiated movements of sub-parallel fractures with branch faults and sub-orthogonal fractures determined the formation of step structure of relief where the mantle of weathering was developed. The regularity of ilmenite concentration within the mantle of weathering depending of its relief is shown. It is marked the disparity of high ilmenite concentrations in the mantle of weathering to the ore varieties of gabbroids in the layered series. The highest ilmenite concentrations are characteristic for the relatively elevated parts of the mantle of weathering. On the slopes the partial decreasing of ilmenite content is taking place which is connected with the influence of wash-out of particles by underground waters. In conditions of the highest head of waters in the gruss horizon it is real the manifestation of internal erosion – the mechanical removal form the stratum of rock the fine clay particles by underground waters that is allow to select the specific process of ore forming on this deposit. Taking into account that this deposit is the second on the titanium reserves after Stremyhorod deposit, for the elaboration of the basis for its rational development it is need to research in details the connections of the relief of the mantle of weathering, erosion processes in the different geological epochs and ilmenite content in area and in cut. This deposit didn’t developed because of long-term payback period. Besides apatite and ilmenite it is possible to extract scandium and vanadium from the Torchyn deposit ores. The kaolin is also valuable component for production of building materials is in the Torchyn ores. So, complexity of the Torchyn deposit is confirmed by the results of computer modeling and geological - economical calculation. This alloved to decreasethe payback period up to 3 years. As a result of the conducted researches a database is created on a deposit with actual attachment to the world system of co-ordinates. The geologiсal-technological model of deposit by GIS- facilities is built, the elements of which are the maps of vertical reserve distributing, thickness of ore layer and overburden, integral index that is expected as a difference between the conditional cost of ilmenite concentrate and charges on implementation of stripping works and processing of productive layer. Based on the created computer model, distributing of ilmenite is analyzed in Torchyn deposit and the blocks of the primary mastering are selected. The offered order of separate blocks development with subsequent recultivation gives an extractive enterprise economic stability from the beginning of development to the complete mastering of deposit’s reserves. Keywords: residual deposit, ilmenite, mantle of weathering, hypsometry of the surface, vertical reserve, geologic-technological model, integral index, eluvium, kaolin, gruss.