Volume 69, Nº 5 (2024)

The problem of identifying rare PGE-Cu-Ni ore-bearing intrusions among the huge array of ore-free mafic bodies in the northwest of the Siberian Platform has been faced by researchers for several decades. For its solution, a complex of geological and geophysical methods is usually used. Geochemical studies based on modern analytical data, such as elemental and isotopic data, are much less frequently used for this purpose. We used such an approach in the study of some Norilsk complex bodies containing sulfide mineralization. The example of the Maslovskoy deposit located in the Norilsk basin demonstrates the characteristic features of ore-bearing rocks that can be used in the search for new promising targets. For the rocks of the Maslovskoy deposit, represented by two sections from cores OM-4 and OM-24, geochemical parameters were obtained that fit into the ranges of ε_Nd = 1.0 ± 1.0 and (La/Lu)_n = 2.3 ± 0.8, which distinguish the magmatic bodies of the Norilsk ore region with unique sulfide ores from the barren ones. The ⁸⁷Sr/⁸⁶Sr ratios in the representative gabbroic rock’s samples of the vertical cross-sections of the Maslovskoy deposit vary from 0.7056 to 0.7069. As PGE accumulate in the rocks, the Pd/Pt ratio increases from ~1 at clarke-level contents to ~3 in rich ores. No evidence of assimilation by melts of silicate rocks in situ was found.

The processes of albite ordering in the range of low temperatures 500–150°C at a pressure of 0.5–1 kbar in alkaline solutions of sodium hydroxide with an excess of silica have been experimentally studied. Based on the data of our experiments and literature data on the ordering of albites and felsic plagioclases, dependences have been derived that make it possible to estimate the temperature from the degree of their structural ordering. The temperatures for plagioclase-bearing parageneses of various natural complexes of the greenschist facies of metamorphism have been determined.

The article assesses the transformation of the chemical composition of surface waters in the southeastern part of the Khibiny mountain massif after the beginning of development of the Oleniy Ruchey apatite-nepheline ore deposit in 2012. The influence of the Oleniy Ruchey Mine was reflected in an increase in water mineralization (by an order of magnitude) and in a change in the ratio between the basic ions in water objects receiving runoff from mines, rock dumps and tailings, compared to watercourses not affected by the mining enterprise’s activities. Natural hydrocarbonate-sodium water composition with a mineralization of 10 mg/l was transformed into nitrate-sodium or sulfate-calcium. The content of nitrogen group compounds in the water of Lake Komarinoe, which receives wastewater from the tailings pond over the ten-year history of the mining and processing plant, has increased by two orders of magnitude, and the nitrate ion is part of the basic ions. The concentrations of other basic ions and mineralization in this lake increased by an order of magnitude, as well as the content of trace elements (Sr, F, Mo), which are part of the main rock-forming minerals of apatite-nepheline deposits. Increased mineralization (up to 260 mg/l), pH value (up to 10) and a modified chemical composition compared to background objects were noted in mine wastewater. They are characterized by a hydrocarbonate-sodium composition with a large proportion of nitrates and sulfates. Mine wastewater contains increased levels of compounds of nutrients, organic matter and a number of microelements (Al, Fe, Sr, Cu, Mn, Zn and Cr). It has been established that geochemical modifications in the quality of surface water have local characteristic and are typical for water objects receiving wastewater from a mining enterprise, in contrast to metallurgical plants, the atmospheric emissions of which have a polluting effect over tens and hundreds km.