Ашық рұқсат
Рұқсат берілді
Тек жазылушылар үшін
Том 67, № 6 (2025)
Articles
FROM THE STRUCTURES OF ORE FIELDS TO THE METALLOGENY OF GOLD: TO THE 90th ANNIVERSARY OF YURI GRIGORYEVICH SAFONOV
Аннотация
The article is dedicated to the memory of the outstanding scientist in the geology of gold deposits, corresponding member of the Russian Academy of Sciences Yu.G. Safonov. In this paper the main stages of his scientific work, the results of which have made a great contribution to the formation theory of hydrothermal ore deposits, are considered. He has systematized the geological elements of deposit structures at different levels of lithosphere. Yu.G. Safonov was standing at the very beginning in using the remote sensing of the Earth's surface, and for the first time he pushed the idea about spectral images of ore-bearing areas. His ideas formed the basis of the development of a three-parameter aerial survey method as a method of prospecting and delineating deposits. A special place in Yu.G. Safonov's research was occupied by the problems of metallogeny of gold and gold-uranium ore deposits, their polygenic multistage formation. A new genetic model of the gold-uranium reefs of the Witwatersrand and a model of the formation of the Adrasman-Kanimansur ore-magmatic system, which formed 11 deposits of silver, polymetals, copper-bismuth and uranium ores, have been developed. A concept on the anomalous effect of radiogenic heat on the petrochemical differentiation of melts and various metallogenic specialization of magmatic ore-generating systems, ensuring their high productivity, has been developed. Based on the results of studying endogenous gold and complex gold-uranium deposits of the world and Russia, Yu.G. Safonov developed a classification of the geological and genetic types of these deposits. Considerable attention he paid to the situation and prospects of Russia's mineral resource base development.
Geology of Ore Deposits. 2025;67(6):743-753
743-753
OROGENIC GOLD DEPOSITS: GEODYNAMICS AND SYSTEMATICS (25 YEARS – SOME RESULTS)
Аннотация
In the article, following S.S. Smirnov's ideas, the widely known orogenic type of gold deposits is considered and the current state of the role of this type in the systematics of gold mineralization is assessed. The advantages and disadvantages of the orogenic type isolation are shown, a conclusion is made about the need to take into account the mineralogical features of ores when classifying gold ore objects, and the position of orogenic gold deposits in the evolution of geodynamically diverse orogenic belts is considered.
Geology of Ore Deposits. 2025;67(6):754-765
754-765
MINERAL COMPOSITION AND FORMATION CONDITIONS OF COPPER-SULFIDE ORES OF THE AGINSKOYE Au-Ag DEPOSIT, KAMCHATKA, RUSSIA
Аннотация
The article presents the results of mineralogical and geochemical studies of copper-sulfide ores from the Vyun ore occurrence, which is part of the Aginskoye gold-silver-telluride deposit, located in the Central Kamchatka Mining District. The Vyun ores are represented by ribbon-like and lens-shaped vein bodies, the core of which is composed of a quartz vein. The veins are often replaced by veinlets, sometimes without a distinct core. As a result of detailed mineralogical studies, two mineral associations have been established: the bornite-digenite-telluride and the gold-chalcopyrite-bornite. The last one includes gold-silver tellurides. Bornite is characterized by high concentrations of Mo (10.5 ppm) and W (19.7 ppm) and the presence of solid solution decomposition structures, such as bornite-chalcopyrite and bornite-digenite. The native gold has a high purity (870–980). It is assumed that the copper-sulfide ores of Vyun were formed in two stages of endogenous mineral formation with significant sulfur fugacity, variable oxygen potential, and low tellurium activity. During the crystallization of high-sulfide minerals, there were fluctuations in composition with a gradual drift towards enrichment in copper. The structures of solid solution decomposition based on bornite were formed at temperatures below 265 °C and are associated with a decrease in the solubility of chalcopyrite and digenetic in the low-temperature modifications of bornite, while the joint crystallization of bornite and chalcopyrite corresponds to high-temperature crystallization.
Geology of Ore Deposits. 2025;67(6):766-785
766-785
230Th/U DATING OF SEAFLOOR MASSIVE SULFIDES FROM SEMENOV-5 HYDROTHERMAL FIELD, MID-ATLANTIC RIDGE
Аннотация
Dating of seafloor massive sulfides (SMS) forming on the ocean floor is a complex task, largely due to the multistage deposition of ore minerals and the influence of changing physicochemical conditions on the isotopic geochemical system during the interaction of hydrothermal fluids with host rocks and near-bottom seawater. Based on data obtained for the ultramafic hosted Semenov-5 field of the Mid-Atlantic Ridge (MAR), the possibilities and limitations of the 230Th/U method are demonstrated, particularly concerning the formation of the radiometric system in environment above and below the paleo-seafloor level. Age of surface ores is ranging from ~60 to ~8 thousand years. However, dating of subsurface sulfides was not possible due to the minimal input of near-bottom seawater in the deposition process beneath the seafloor. The study indicates that massive sulfides formed beneath the seafloor are of metasomatic origin, suggesting that massive sulfide mineralization may not be confined to the paleo-seafloor but could extend to greater depths. This finding has significant implications for other sulfide deposits within the MAR as well and may lead to a reassessment of their resource potential. The age dating of SMS from Semenov-5 field is comparable with other fields within the Semenov cluster. The data obtained highlight the long and complex history of hydrothermal circulation and massive sulfide formation within ultramafic rocks of ocean core complexes in slow-spreading mid-ocean ridges.
Geology of Ore Deposits. 2025;67(6):786-797
786-797
DEVONIAN GABBROIDS OF THE NW RUDNY ALTAI AS INDICATORS OF THE LITHOSPHERIC MANTLE CONTRIBUTION TO PETROGENESIS AND ORE FORMATION
Аннотация
The results of petrogeochemical and Sm-Nd isotopic characterization and U-Pb ages of basic intrusive rocks of the NW Rudny Altai, synchronous with contrasting rift-related basalt-rhyolite volcanism on the Devonian continental margin of the Siberian continent, are presented. The gabbroids belong to the low-titanic, high-magnesian tholeitic series, which is partially differentiated and has no continuous sequence with Devonian granitoids. The rocks have low concentrations of incoherent elements, Nb/YPM <1 with strong depletion of Nb relative to LREEs and Th (Nb/Nb* = 0.2–0.3), combined with La/Smn >1.5, Hf/Hf* ~0.9 and εNd (T) from +2.9 to +4. The geochemical characteristics of the rocks are intermediate between basalts of margin island arcs and back-arc basins. U-Pb isotopic ages (LA-ICP-MS) of gabbroids from zircons are ~383 Ma. Variations in rare element compositions suggest the formation of primary basic magmas from a weakly depleted mantle that was metasomatically modified by subduction fluids/melts and/or plume melts long before the generation of basic magmas. The Nd isotopic composition of the gabbroids is consistent with the evolution of the Precambrian lithospheric mantle of oceanic origin, which was incorporated into the folded frame of the Siberian continent during the Early Paleozoic accretionary stage. The obtained results confirm the hypothesis of the relationship of the ore component with the subcrustal lithospheric mantle of Rudny Altai. According to the geodynamic scenarios, the Devonian basic magmas were formed in an extensional setting during reactivation of the marginal continental lithosphere, which, according to our interpretation, corresponds to the rifogenic (initial) stage of development of West Pacific-type back-arc basins.
Geology of Ore Deposits. 2025;67(6):798–828
798–828
TELLURIDE MINERALOGY IN ORES OF THE BIRGILDA PORPHYRY COPPER DEPOSIT (SOUTH URALS, RUSSIA)
Аннотация
Telluride-base-metal mineralization within silica alteration of the Birgilda porphyry copper deposit (South Urals, Russia) was studied with optical and electron microscopy with energy dispersive detector, as well as with X-ray diffraction analysis. The silica alteration is composed of quartz (60–90%) and muscovite 2М1 (up to 30%), and minor amount of illite. Ore minerals are represented by (in order of descending abundance) pyrite, galena, sphalerite, chalcopyrite, tetrahedrite and minerals of tellurium. The latter ones include: altaite PbTe, tellurobismuthite Bi2Te3, kochkarite PbBi4Te7, volynskite AgBiTe2, coloradoite HgTe, native tellurium, hessite Ag2Te, stützite Ag5-xTe3, and petzite Ag3AuTe2. Single occurrences of apatite, barite, and minerals similar to monazite and xenotime were also noted. The described assemblages and wall-rock alteration are typical for upper levels of a porphyry system and belong to intermediate argillic alteration. The observed variability of tellurium minerals is determined by fS2 and fTe2 fluctuations at temperature of approx. 200 to 250 °C.
Geology of Ore Deposits. 2025;67(6):829–843
829–843
MINERALOGICAL AND GEOCHEMICAL FEATURES OF Fe–Ti ORE OCCURRENCES OF THE KOPAN AND MATKAL MASSIFS (KUSA-KOPAN COMPLEX, SOUTH URAL)
Аннотация
The article provides new materials on Fe–Ti mineralization in rocks of the Kusa-Kopan complex. It is shown that the change in the basicity of rocks in the process of differentiation is classical and consists of an increase in the amount of silica in late differentiates (from pyroxenites to leucocratic granites with intermediate varieties) with a tholeiitic (Fenner) trend. The normalized distribution of rare earth elements and the degree of their fractionation indicate their coherent behavior in the process of magmatic differentiation. Features of noble metal geochemical specialization lie in the complementarity of graphs of normalized contents of noble metals, which differ from each other only quantitatively. It has been established that the formation of rhythmic layering is due to the action of the mechanism of directional crystallization, through the movement from bottom to top of the solidification front (crystallization zone), consisting of crystalline liquidus phases when the residual melt is squeezed into the main volume with its enrichment in low-temperature components. When the composition of the melt is close to subeutectic, the process will acquire an “oscillating” character, when the binding of melt components in the mineral phase (clinopyroxene) shifts the equilibrium and crystallization of another phase (plagioclase) becomes possible. At the stage of formation of the crystallization zone, (titanium) magnetite forms disseminated mineralization, but as the solidification front moves from bottom to top, the mechanism of gravitational sedimentation begins to operate, which leads to its concentration in the form of veinlets among the crystalline liquidus phases. The peculiarities of the internal structure and chemical composition of ilmenite-titanium magnetite mineralization are explained by the existence of high-temperature (1300–1400 °C) homogeneous phases of Fe–Ti minerals, in which, with slow cooling of the massif and autometamorphism, the system is recoullibrated with the decomposition of solid solutions, crystallization of minerals of the spinel family and the formation of magnetite veinlets in ilmenite.
Geology of Ore Deposits. 2025;67(6):844-870
844-870
EUDIALYTE GROUP MINERALS IN RARE METAL NEPHELINE SYENITES OF THE KHASHATYN-KHAR MASSIF (NORTHWESTERN MONGOLIA) – INDICATORS OF POTENTIAL RARE METAL ORE
Аннотация
Khashatyn-Khar syenite massif with agpaitic mineralisation is located in Caledonian fold structures of the southern rim of Tuva–Mongolian Superterrane. Nepheline syenites and numerous dykes consisting of agpaitic varieties of nepheline syenite with aegirine, pectolitic-serandite series minerals, fluorite and eudialyte group minerals (EGM), are well developed in apical part of the massif. Compared with other rocks of the massif, these rocks are enriched in Zr, Nb, REE and EGMs are common. Composition and diversity of species of less common minerals in the dykes varies widely. This is a result of both variations in initial melt composition and of autosomatic rock transformations caused by interaction with water-rich intergranular resitite melts. Primary EG minerals include EGM of a continuous series from iron-rich (up to 4.8 wt.% FeOtot), Na-poor (up to 3.4 wt.%) and water-rich (up to 8.6 wt.%), compositionally close to liyukhinite, as well as species similar to Georgbarsanovite и Davincitie. EGMs in insular polymeral intergrowths with catapleite and other minerals are, presumably, of secondary origin. They are extremely rich in Mn (up to 11 wt.%) and their composition approaches Mn-rich minerals such as Zirsilite-Ce or Carbokentbrooksite, or can be considered as a Nb-variety of Amableite-Ce.
Geology of Ore Deposits. 2025;67(6):871–893
871–893
ORE MINERALIZATION IN THE KHARBEY METAMORPHIC COMPLEX IN THE ZONE OF THE KHADATA-KHANMEI THRUST (POLAR URALS)
Аннотация
Ore mineralization (Au, Ag ± Pt, Pd) and host metasomatic alteration were studied in amphibolites of the Kharbey metamorphic complex at the Polar Urals. The predicted gold field is well exposed in the Skalisty stream in the zone of the Khadata-Khammei thrust, controlled by a fault of the north-western direction. The host rocks are represented to varying amphibolites (up to the epidote-amphibolite facies of elevated pressures). During diaphthoresis, amphibolites underwent alteration transformations: chloritization, albitization, muscovitization, and silicification. The main part of the sulfides was deposited during the late silicification processes. Ore minerals are represented by sulfides and occurring as rare inclusions tellurides, selenides and native metals. Three stages of the sequential hypogenic hydrothermal ore-formation processes were identified. At an early stage of hydrothermal-metasomatic changes of rocks, high- and medium-temperature ore minerals were formed — pyrite, pentlandite, Ni-pyrrhotite, chalcopyrite and molybdenite, associated with chlorite (ripidolite). The next stage was associated with high- and medium-temperature hydrothermal processes and the development of quartz veins and veinlets, when the following minerals crystallized: pyrite, matilidite-galena, galena, sphalerite, molybdenite, chalcopyrite, bornite, pyrrhotite, chromferride, mercury electrum, tsumoite and low- and medium-fineness gold. Medium- and low-temperature hypogenic minerals of the third stage are represented by nickel- and cobalt-containing pyrite, chalcopyrite, galena, clausthalite-galena, hessite, melonite, merinskiite and merinskiite-melonite, associated with pycnochlorite-brunswigite and rhipidolite-daphnite. Recent hypergenic changes are characterized by the formation of secondary acanthite, hessite, naumannite-acanthite, hessite-acanthite-naumannite, native silver and covellite in ores.
Geology of Ore Deposits. 2025;67(6):894–912
894–912