The Oktyabrsk PGE-Cu-Ni deposit is one of the largest resources in the Norilsk–Talnakh ore district, Russia, and it is viewed as an ore giant on a global scale. It contains three types of ores: massive, disseminated and veinlet-disseminated. The two former ore types were formed by a liquation process, whereas the latter was associated with fluid-induced selective metasomatic replacement of metamorphosed wall rocks. One of the major ore minerals in all ore types is chalcopyrite. In this study, we determined concentrations of trace elements in this mineral using laser ablation inductively coupled plasma mass spectrometry. It appeared that standard geochemical tools, such as plotting the data in the form of diagrams of normalized concentrations, binary and ternary plots, do not allow one to distinguish chalcopyrite from visually and genetically different ore types. In contrast, more advanced statistical methods such as cluster analysis show different groupings of elements for each ore type. Based on the element clustering, a classification tree was suggested, which allowed for the differentiation of massive, disseminated and veinlet-disseminated ore types of the Oktyabrsk deposit by Se, Te, Cd and Pb concentrations in chalcopyrite with a success rate of 86%. The general feature is that chalcopyrite of veinlet-disseminated ore is poorer in these elements compared to chalcopyrite of the two other ore types. Chalcopyrite of massive ore is poorer in Se and Te when compared to chalcopyrite of disseminated ore.

The initial stage of Rodinia supercontinent break-up occurred at about 750 Ma. It preceded formation of the Irkutsk and Franklin large igneous provinces (LIPs) at 712 ± 2 to 739 ± 8 Ma. These LIPs were emplaced within the formerly connected Laurentian and Siberian cratons. The Kingash massif is located in the Precambrian Kan terrane in direct contact with the Siberian Craton at its southwestern boundary. It has been linked to an important suite of mafic–ultramafic intrusions that border the southern margin of the Siberian craton, and that have been inferred to belong to the Irkutsk LIP. The massif is also significant, because it hosts platinum group element (PGE)–Cu–Ni-rich mineralization and is the only large deposit in the region. However, despite numerous dating attempts, the age of the massif had not been resolved. A significant difficulty is post-magmatic recrystallization at amphibolite facies that affected the rocks of the massif. In this study we used U–Pb dating of zircon, titanite and apatite from rocks of the Kingash massif and cross-cutting granite and monzonite veins. The oldest igneous zircon grain of the Kingash massif analysed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) yields an age of c. 750 Ma, taken as a tentative age of magmatism. Dating of multiple grains of metamorphic zircon by chemical abrasion isotope dilution thermal ionization mass spectrometry yielded 564·8 ± 2·2 Ma, which is in agreement with LA-ICP-MS titanite ages of 557 ± 19, 565 ± 35 and 551 ± 17 Ma. Apatite of two different samples showed ages of 496·4 ± 7·9 and 497·0 ± 1·8 Ma (LA-ICP-MS), which are interpreted as the time when the terrane cooled below the closure temperature of apatite. Using our new data we suggest that at the time of the Irkutsk–Franklin LIP event the Kan terrane was a part of Rodinia, then it separated from either Siberia or Laurentia during the break-up of Rodinia and finally collided with Siberia at 560 Ma, the time of regional amphibole-facies metamorphism.

The results of experimental studies on the development of scientific and technical foundations of a method to obtain cubic titanium carbide in plasma of a DC arc discharge initiated in air have been presented. According to X-ray diffractometry of powder materials obtained in a series of experiments, the dependences of phase composition of the product on the duration of synthesis have been determined. Using the results of scanning electron microscopy and energy dispersion analysis, several morphological types of titanium carbide particles, which are formed as a result of uneven energy distribution in the reaction volume, have been revealed.

The relevance of the study is determined by obtaining new data concerning mineral composition, textural and structural features, hydrothermal-metasomatic zoning, fluid regime, and types of gold mineralization of two most contrasting areas of the Svetloe epithermal district (Khabarovsk Territory), formed in different-aged parent rocks of the Late Cretaceous age (K-2) of the Khetanian Formation basic composition in the Cognac-Santonian Stage (d. Emmy) and discordant bedding felsic rocks of the Urak Formation of the Campanian-Maastrichian Stage (d. Elena). The selected objects are characterized by different levels of zone erosion and most fully reflect the diversity of altered rocks of the Svetloe epithermal district. Altered rock represented by weakly altered rocks of the Khetanian Formation within the Emmy deposit and strongly altered, including hypergene processes, acidic rocks prevailing on the territory of the Elena deposit. The data obtained play an important role in establishing the type of epithermal deposits, forecasting mineralization at depth, and can also be used to identify search criteria and features of similar objects both in the Okhotsk-Chukotka volcanic belt and beyond. The aim of this work is to study the hydrothermal-metasomatic zoning, material composition, textural and structural features, fluid regime, as well as the forms of gold occurrence in the Svetloe epithermal ore district using the Emmy and Elena deposits as example. The objects of the study are ores, metasomatites and weakly altered parental rocks in the form of core, ore and chipped samples taken as a result of research work from eight wells and two operating open pits. The rocks were studied by optical and electron microscopy methods using energy dispersive spectroscopy, as well as by X-ray diffraction analysis, microthermometry, and Raman spectrometry. As a result of the studies, it has been established that the altered zoning of the Svetloe epithermal district includes an axial zone of residual quartz with various texture and structural features - mosaic, feathered, collomorphic, and crustifying structure and a halo of interbedded linearly elongated zones of altered rocks composed of alunite-and dickite-quartz zone, which are replaced at more distance from the axial zone by sericite and illite-chlorite zones of the propylite formation, with a lesser degree of elaboration of volcanic and volcanicclastic rocks of the acid composition of the Urak Formation, the ore-containing area of the Elena, and of intermediate and basic composition including the Emmy deposit. The main part of mineralization is associated with the residual quartz zone. The morphology of ore bodies is represented by sub-layer linear keeled deposits with mushroom-like swells in paleo-grooves up to 110 m. The average thickness of ore bodies varies from 12 to 60 m, up to 700 m long, and 100...240 m wide. The fall of the ore zones is gentle, steep near the paleo-grooves with uneven or very uneven distribution of the valuable component. The average grade of gold in ores is 2,5 g/t. The composition of hypogene sulfide mineralization is represented by sulfides of polymetals Cu, Pb, Zn, Fe in the mineral form of pyrite, galena, sphalerite, chalcopyrite, and tennantite-tetrahedrite. Within the ore bodies of the Emmy deposit, the mineral association of sulfides of the hydrothermal stage is more than 5 vol. % and distinguished by the diversity and abundance of tellurides. Gold mineralization is represented by two types: Au-Ag and Au-Agtelluride. Au-Ag ores are represented by primary ores with an average fineness of similar to 900 % developed within the Emmy deposit and secondary (oxidized) ores with a fineness of up to 1000 % prevailing at the Elena deposit. According to the results of the study of vapor-liquid inclusions in quartz, the hydrothermal-ore process at the Emmy deposit proceeded at 260...330 degrees C. Microcryothermometric experiments of the Elena deposit indicate the 200...240 degrees C. range of the hydrothermal process. In terms of the material composition of altered rocks, hypogene sulfide association, and fluid regime, the Svetloe epithermal district belongs to the sulfate-acid and medium-acid (HS-IS) type, showing the prospect of detecting porphyry mineralization at depth.