On the issue of improving forecasting and prospecting complexes for identifying new sources of acutely scarce mineral raw materials (using the example of placer boulder chromium ores)

Abstract

Te purpose of the work is to improve forecasting and search complexes to identify new sources of extremely scarce mineral raw materials for the Russian industry. Research methodology. Analysis of the available information on the features of the geological structure and conditions for the placement of shallow slope placers of boulder chromium ores, reconstruction of the buried relief of the bedrock, study of the structural features of the bedrock and modern (daytime) surface of the placers using analytical methods (trend analysis, etc.), study of the spatial variability of the estimated parameters of placer objects, identifcation of factors controlling the distribution of placer productivity. Results. Te reconstruction of the bedrock surface of the most fully studied type placer of cobblestone chrome ores of the Saranovskaya group (placer no. 2) was performed, the spatial variability of the estimated parameters of the placer was studied in the plan, and the factors controlling the distribution of the productivity of loose deposits were determined. Te longitudinal profle of the bedrock surface of the placer is an alternation of slightly inclined and subhorizontal areas, the formation of which is probably due to the repeated manifestation of erosion cycles in the history of the development of the region. Te distribution of productive deposits thickness in the direction of placer elongation is periodic. Te increased thickness of the productive layer runs to areas where slightly inclined sections of the bedrock are replaced by more gentle (sub-horizontal) ones, to the bases of “terraced” steps in the relief. Overall, there is a general trend towards an increase in the thickness of the productive layer down the slope. Te distribution of placer productivity indicators is uneven; in the direction of the elongation of the placer, zones of increase, maximum and decrease in productivity are distinguished, which are typical features of the “elementary placer” according to N. A. Shilo. Tere is a clear confnement of the most productive areas to the subhorizontal morphostructural elements of the buried bedrock in the middle part of the placer. Te microforms of the buried relief, which are associated with the most productive areas of the slope deposits, manifest themselves as negative “remains” of the linear trend of the bedrock surface marks. Te morphostructural elements of the buried bedrock of the shallow placer are inherited in the modern relief. Conclusions. Te analysis of the presented materials emphasizes the importance of morphostructural studies in predicting and searching for placers of pebble chromium ores of close ablation. During prospecting, the task of ultra-precise surveying of the day surface relief with additional mathematical transformations of the obtained data seems to be an urgent task.