Том 58, № 4 (2016)

The worldwide distribution of large and superlarge mineral deposits (LSLDs) on a geological time scale is analyzed. It has been established that their formation from Eoarchean to Cenozoic was nonuniform in time. The maxima and minima of ore generation intensity correlate well with global cyclical processes, eventually resulting in the assembly and breakup of supercontinents. The periods of supercontinent amalgamation are characterized by the highest rate of continental crust growth due to the contribution of juvenile sources, a maximum of orogenic activity, and the most intense deposit formation. Periods close to betweencycle boundaries are distinguished by a low intensity of both endogenic and ore-forming processes. As follows from the available data, the number of known LSLDs slightly decreases from the Kenoran to Columbian cycle, significantly decreases in the next Rodinian cycle, which, in turn, is followed by abrupt growth in the Pangaean and Amasian cycles, especially as concerns LSLDs of the granitoid-related class. The intensification of metallogenic activity correlates with a commensurable increase in orogenic activity of the Earth’s crust probably caused by continental crust expansion, an increase in the number of sialic blocks participating in the formation of accretionary and collisional orogens, and acceleration of lithospheric plate motion. Some trends are also described for other LSLD classes (basic–alkaline, volcanic-hosted massive sulfide, sedimentary, epigenetic sediment-hosted), caused to a certain extent by supercontinent cycles and their evolutionary variations.

The mineral parageneses and succession of their formation are considered for the first time for the Zverevsky, Orekhovy, and Vodonosny ore lodes of the Lebediny gold deposit and the Radostny prospect in the Central Aldan ore district, which are genetically related to the epoch of Mesozoic tectonomagmatic reactivation. The orebodies, represented by two morphological varieties—ribbonlike lodes and steeply dipping veins—are hosted in lower part of the Vendian–Cambrian dolomitic sequence, which is cut through by Mesozoic subalkaline intrusive bodies. The chemistry of fahlore and rare minerals, including native gold and bismuth, altaite, aikinite, tetradymite, and sulfosalts of lillianite series, has been studied. Native gold is related to the late hydrothermal process and occurs in skarn and in quartz–tremolite–sulfide and quartz–carbonate–sulfide veins. The data on stable sulfur (δ³⁴S) isotopes of sulfides, oxygen (δ₁₈O) and carbon (δ₁₃C) isotopes of carbonates, as well as on fluid inclusions in various generations of tremolite and quartz, provide evidence for the heterogeneity of ore-bearing solutions, their relationships to magmatism, the depth of the source feeding each specific lode, and different sources of ore-forming hydrothermal solutions.

Ruby and spinel occurrences hosted in marble on the eastern slope of the Urals are considered. Ruby- and spinel-bearing marble is a specific rock in granite-gneiss complexes of the East Ural Megazone, which formed at the Late Paleozoic collision stage of the evolution of the Urals. Organogenic marine limestone is the protolith of the marble. No relict sedimentary bedding has been retained in the marble. The observed banding is a secondary phenomenon related to crystallization and is controlled by flow cleavage. Magnesian metasomatism of limestone with the formation of fine-grained dolomite enriched in Cr, V, Ti, Mn, Cu, Zn, Ga, and REE took place at the prograde stage of metamorphism. Dedolomitization of rocks with the formation of background calcite marble also developed at the prograde stage. Mg-calcite marble with spinel and ruby of the first type formed in the metamorphic fluid circulation zone. Magnesian metasomatism with the formation of bicarbonate marble with ruby, pink sapphire, and spinel of the second type developed at the early retrograde stage. The formation of mica-bearing mineralized zones with corundum and spinel of the third type controlled by cleavage fractures is related to the pneumatolytic–hydrothermal stage. The data on ruby-bearing marble in the Urals may be used for forecasting and prospecting of ruby and sapphire deposits hosted in marble worldwide.