| Реферат: | eng: The source of sulfur in giant Norilsk-type sulfide deposits is discussed. A review of the state of the problem and a critical analysis of existing hypotheses are made. The distribution of delta S-34 in sulfides of ore occurrences and small and large deposits and in normal sedimentary, metamorphogenic, and hypogene sulfates is considered. A large number of new delta S-34 data for sulfides and sulfates in various deposits, volcanic and terrigenous rocks, coals, graphites, and metasomatites are presented. The main attention is focused on the objects of the Norilsk and Kureika ore districts. The delta S-34 value varies from -14 to +22.5 parts per thousand in sulfides of rocks and ores and from 15.3 to 33 parts per thousand in anhydrites. In sulfide-sulfate intergrowths and assemblages, delta S-34 is within 4.2-14.6 parts per thousand in sulfides and within 15.3-21.3 parts per thousand in anhydrites. The most isotopically heavy sulfur was found in pyrrhotite veins in basalts (delta S-34 = 21.6 parts per thousand), in sulfate veins cutting dolomites (delta S-34 = 33 parts per thousand), and in subsidence caldera sulfates in basalts (delta S-34 = 23.2-25.2 parts per thousand). Sulfide ores of the Tsentral'naya Shilki intrusion have a heavy sulfur isotope composition (delta S-34 = +17.7 parts per thousand (n = 15)). Thermobarogeochemical studies of anhydrites have revealed inclusions of different types with homogenization temperatures ranging from 685 degrees C to 80 degrees C. Metamorphogenic and hypogene anhydrites are associated with a carbonaceous substance, and hypogene anhydrites have inclusions of chloride-containing salt melts. We assume that sulfur in the trap sulfide deposits was introduced with sulfates of sedimentary rocks (delta S-34 = 22-24 parts per thousand). No assimilation of sulfates by basaltic melt took place. The sedimentary anhydrites were "steamed" by hydrocarbons, which led to sulfate reduction and delta S-34 fractionation. As a result, isotopically light sulfur accumulated in sulfides and hydrogen sulfide, isotopically heavy sulfur was removed by aqueous calcium sulfate solution, and "residual" metamorphogenic anhydrite acquired a lighter sulfur isotope composition as compared with the sedimentary one. The wide variations in delta S-34 in sulfides and sulfates are due to changes in the physicochemical parameters of the ore-forming system (first of all, temperature and P-CH4) during the sulfate reduction. The regional hydrocarbon resources were sufficient for large-scale ore formation. (C) 2018, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.
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