Ore Region Research Articles

Structure of the Muruntau gold ore region in the Kyzyl-Kum desert (Central Asia)

The giant gold deposit Muruntau in most works belongs to the “orogenic type”. However, in the description of the geology of the deposit, there is usually no information about the stages (deformation, metamorphism) and the role of regional processes in the formation of host and mineralized rocks of the deposit. Our fieldwork provides unique geological evidence and previously unpublished data that are not reported in any other publications to date. This article presents the results of a detailed structural study of the terrane hosting the Muruntau gold deposit on the example of four sites and the results of deep drilling of two wells. The conducted studies confirm that the lowest Muruntau megaterrane consists of multi-stage metamorphosed Neoproterozoic–Early Paleozoic sedimentary-volcanic rocks and Late Paleozoic carbonate sediments overlain by Late Carboniferous flysch and olistostrome in the top. Two main stages (D1 and D2) of rock deformation in the lower part of the megaterrane associated with the Early Paleozoic accretion and two subsequent stages (D3 and D4) associated with the Late Paleozoic accretion and orogeny are described. Thrust processes D2 and D3 caused the formation of recumbent folds of different orientation and vergence. The normal antiform (D4) extending W–E is an orogenic fold. The Muruntau gold deposit is located in a regional synmetamorphic thrust zone called the Main Muruntau Thrust (MMT), which formed during the Early Paleozoic D2 stage. The MMT is responsible for the formation of secondary rock anisotropy along the cleavage of the D2 recumbent folds and conformal lens-like body of mineralized rocks and gently sloping veins with an area of 7.0 × 2.6 km. The internal structure of the deposit retains fragments of deformed gold quartz veins into recumbent folds. These structural data make it possible to link low-grade gold mineralized zones with Early Paleozoic deformations. We suggest that rock anisotropy within the MMT controlled mineralization twice: in the Early Paleozoic as a synmetamorphic flat high-permeable zone and in the Late Paleozoic as a relatively low-permeable zone for post-magmatic fluids.

Prospects for the development of the deposits of the Yuzhno-Yansky tin ore district

A brief review of the mineral resource base of the native tin of the Republic of Sakha (Yakutia) is given with a description of the economically important objects of the South Yansky tin ore region. The degree of assimilation of the mineral resource base of the tin in the Russian Federation is low. The undistributed fund has some high-grade ore deposits located within the region involved in the development. The most significant are the deposits of Burgachan, Ilintas, Alys-Khaya, which, together with prospecting ore occurrences, are considered as the basis for the creation of a large cluster for the extraction and production of tin. The involvement of these deposits in exploitation is hindered by their location in the specially protected natural area (SPNT) of Khotu. It is proposed to remove objects from the specially protected natural area.

New prospects of uranium mineralisation of the Trans-Urals based on regional geochemical survey data

Introduction. The article presents the prospects of uranium mineralisation in the Trans-Urals. The study area lies in the southwestern part of the Western Siberian Plate and belongs to the West Siberian uranium-bearing belt. The belt controls the paleovalley type uranium infiltration mineralisation of the Mesozoic age. The data obtained from the anomalous geochemical area (AGA) of the Dolmatovsky and Khokhlovsky uranium ore regions are used as a reference with suitable geochemical characteristics. Aim. The aim of this study is to identify and forecast new uranium ore regions that are promising for the discovery of industrial deposits of paleovalley type uranium.Materials and methods. The research was conducted while establishing the geochemical bases on a scale of 1 : 1 00 000. Over 2000 samples of soils and bottom sediments were evaluated on a 10 × 10 km grid. The uranium active forms and other 56 elements were detected in the samples. The analysis was carried out by inductively coupled plasma mass spectrometry (ICP-MS) in the FSBI “IMGRE” analytical centre.Results. Besides the known Dolmatovsky and Khokhlovsky uranium ore regions, 31 AGAs with uranium specialisation were identified based on the geochemical data obtained in a well-developed and accessible site. Their prospectivity was assessed according to a set of geological and geochemical criteria. As a result, six new promising areas for discovering industrial uranium deposits were identified, and a significant increase in uranium reserves is expected in the well-known Khokhlovsky region.Conclusions. The practical implication of the study is the forecast of the expansion of the uranium raw materials base around the known deposits with finite raw materials reserves.

Principles governing the selection of ore regions for gold deposit search

Background. In 2020, the Auditing Chamber of the Russian Federation, based on a representative report by its expert analysts M. Men’ and A. Kaulbars, proposed expanding the search for deposits of a number of metals, including gold. Since the fund of easily discovered gold deposits coming to the surface has been significantly reduced, prospecting of ore regions most promising in terms of gold deposits becomes highly relevant.Aim. In connection with the above task, it seems expedient to outline territories within the currently known gold provinces, where the prerequisites and signs of gold ores could be detected with minimal expenditures for their subsequent verification by drilling.Materials and methods. The study involved calculating the shares of the world’s gold reserves attributable to each type of distinguished deposits located in various rocks. The extensive experience of prospecting work carried out in recent decades and culminated in the discovery of the Muruntau deposit in Uzbekistan, a world leader in the development of gold deposits, and Russian largest and giant deposits – Natalka, Sukholozhskoe, Nezhdaninsky, Degdekansky, Maisky, Oktyabrsky, Pavlik, Kupol, as well as the Bakyrchik deposit in Kazakhstan and others, clearly shows that the most promising and largest deposits are selectively localized in favourable rocks and largescale disjunctive dislocations, or faults. To identify favourable rocks, the distribution of the world’s gold reserves in various rocks was analysed, as well as the distribution of reserves in the areas of the largest deposits in ore-bearing faults as the most favourable fault types containing the most powerful and extended gold ore bodies.Results. A comparison of the shares of reserves has shown that the most promising for prospecting are those rock complexes containing the highest proportions of the world’s gold reserves. The article presents the distribution of shares of the world’s gold reserves for near surface and deep-formed deposits of various types. The main share of the world’s gold reserves in deeply formed deposits is shown to be concentrated in the Phanerozoic strata of sandy-clayey composition and in the interlayers of easily replaceable carbonate and amphibolite shales developed in the Proterozoic quartzite-phyllite rocks. The reserves of near-surface gold-silver and gold-telluride ores are selectively located in the young Mesozoic-Cenozoic volcanic rocks of basalt-andesite composition, accompanied by dikes, subvolcanic stocks and the pipes of explosive breccias with large-scale gold ore bodies confined to them. Thus, the most promising areas for prospecting new deposits are those composed of the mentioned rock complexes and crossed by ore-bearing faults, in the zones of which the main largest ore bodies are concentrated. Conclusion. The conducted study into the distribution of the world’s gold reserves in the deposits of various types, as well as the selective localization of ores in deposits with the main and large scale ore bodies in the zones of ore-bearing faults (and, accordingly, containing the concentration of the main share of reserves in a particular deposit), provides a basis for discovering new deposits of the precious metal with minimal expenditures, thus contributing to increasing the resource base of the Russian Federation.

CONTROL FACTORS OF IRON MINERALIZATION IN THE METALLOGENY OF THE LJUBIJA ORE REGION

<p>The control factors of mineralization in the Ljubija ore region are stratigraphic, lithological, magmatogenic, structural-tectonic and hypergenic. The distribution of iron ores in the Ljubija ore region is primarily controlled by the spread of the Olistostrome member of the Carboniferous Javorik flysch formation. Only that member, whether uncovered on the surface or overlain by an Upper flysch member, contains primary siderite-ankerite iron ores. In addition, the distribution of ore bodies is significantly affected by the concentration and location of mineralized limestone and limestonedolomite olistoliths. The seating of carbonate olistolitic bodies in the member is irregular, that is, chaotic. The size, shape, and morphology of these bodies and their boundaries are extremely uneven and diverse, in both primary and tectonic occurrences. Not all olistolitic bodies are mineralized. Those that are can be completely, partially or minimally mineralized. Due to all this, ore bodies and deposits “have no continuity and appear in isolation”. Therefore, there is a high exploration risk. These major irregularities are not characteristic of redeposited powdered limonite ores in Plio-Quaternary lacustrine sediments. Cimmerian lateral ruptures were important for the distribution of hydrothermal solutions and today's distribution of ore deposits and occurrences within ore fields and ore nodes. The hypergenic control factor significantly influenced the forming of iron oxide ores. In the Alpine tectogenesis, old systems of faults and joints were renewed and new created. In this respect, the most significant were transverse, open, steep SW-NE ruptures.</p>

Peculiarities of the raw material base of the Lykhmanivka iron ore region in Kryvyi Rih basin

Lykhmanivka (Inhulets) iron ore district takes the southernmost position in the Kryvyi Rih iron ore basin. In the north, it is bordered by a series of sublatitudinal faults with the Southern Iron Ore District of Kryvbas. The productive strata of the area are Lykhmanivka iron ore pay streak, in the southern part of which the Inhulets deposit of magnetite quartzites is located in the zone of closing of Lykhmanivka syncline. However, in addition to them in the area, there are more than 20 types of other minerals, which are mined by-products and can be successfully used in the national economy. Syngenetic (sedimentation, diagenesis, dynamothermal metamorphism) and epigenetic processes (tectogenesis, metasomatism, hydrothermal processes, hypergenesis), which occurred during the formation of iron ore and host strata area have contributed to the formation of several minerals and rocks, which can be considered as associated complex useful minerals. The relevance of the work is due to the need for detailed research of the localization, formation conditions, directions of use of metallic and nonmetallic minerals of the area, the geological justification for their priority varieties. As a result of these studies, systematization of minerals of the area has been developed, their priority varieties have been identified. Their involvement in mining and processing significantly expands the spectrum of alternative ways of use of minerals and rocks of iron-banded formation, which will contribute to a significant addition to the mineral resource base as in Kryvyi Rih iron ore basin, and in Ukraine as a whole.

Remote Sensing Studies for Mapping of Iron Oxide Regions in Keonjhor district, Odisha, India

Odisha is known for having a bounty of mineral resources, which are required for the economic and industrialdevelopment of the state. Ore minerals such as hematite, magnetite, pyrolusite, psilomelane, chromite etcare richly available in Odisha. A lot work has been done on the mineral property, texture, behaviour ofindividual ions in different chemical conditions within the domain of the aforesaid minerals and a very fewworks has reportedly been done on the spectral behaviour of these ore minerals. For the development ofhuman societies, economic and industrial demand of iron has been raised which resulted in search of newcost-effective techniques for the exploration of ore minerals containing Fe metal. Remote sensing methodsare now considered as modern and cost effective highly dynamic techniques for exploration of economic ore minerals containing iron oxides. In this study, various digitalimage processing techniques of remote sensingsuch as False Colour Composites (FCCs), Band Ratios (BRs), and Principal Components Analysis (PCA) were used on satellite derived images for mapping iron oxide mineralization zone. The results were compared with the already published maps and also with the field inspection. From the results, it was found that various band combinations of BRs and PCA may be used for mapping of iron oxide ore regions.

Mineral potential modelling for gold mineralization within
 the Mesozoic depressions in the Central Aldan ore-placer region
 (on the example of the Upper Yakokut ore field)

In this work, we described the patterns of formation
 and distribution of gold occurrences of various morphological
 types in the terrigenous sequence of the Upper
 Yakokutsk graben depression. We characterized the
 zones of ore-bearing dislocations with increased permeability
 within the ore region confined by regional faults.
 Such zones with a frame-block structure forming the
 nodes of conjugation of regional structures are favourable
 for their repeated resumption and correspond to the
 most prospective areas. The study of native gold from
 ores and surrounding metasomatites showed a large
 variation in its fineness, based on which we can assume
 that the gold ore zones were repeatedly renewed from
 the Middle Jurassic to the Early Cretaceous. A correlation
 was noted for several subordinate structures: zones
 of ore-bearing dislocations – structures of prospective
 areas – ore bodies of various morphologies.
 The terrigenous sequence is considered not only as a
 structure-forming unit but also as a component involved
 in hydrothermal ore formation due to the presence of
 carbonaceous siltstones layers.
 The proposed model of the gold ore region makes it
 possible to allocate the most promising prospective areas.
 The presence of similar graben depressions developed
 in prospective ore regions within the Central Aldan
 ore district indicates the likelihood of identifying
 common patterns of endogenic mineralization within
 them.

ОЦЕНКА ВОДНО-ФИЗИЧЕСКИХ СВОЙСТВ ТЕХНОГЕННЫХ СУБСТРАТОВ ПРИ БИОЛОГИЧЕСКОЙ РЕКУЛЬТИВАЦИИ ОТВАЛОВ КМА

The negative impact of man on the environment is noticeably manifested when mining in an open way, in which the prevailing natural landscape is completely disrupted. The object of the study was the Starooskolsk-Gubkinsky iron ore region of the Kursk magnetic anomaly. For the mining technical stage of reclamation of disturbed territories with unsatisfactory growing conditions, common pine (Pinus sylvestris L.) was chosen for research. In the results of studies of post-technogenic areas, elements of mineral nutrition, water, physical and chemical properties of substrates were determined. According to these data, the particle size distribution of such dumps contains from 6 to 43% of silt particles (less than 0.001 mm). Water-soluble salts in the substrates contain a small amount, and the dry residue ranges from 0.12-0.6%. The amount of organic matter is small and reaches only 0.13-0.66%, and mobile phosphorus 1.8-2.0 and exchangeable potassium up to 16 mg / 100 g. These substrates have a high connectivity, showing degree of bonding between individual particles. According to the analysis of the data, the substrates at this object of study are characterized by water-physical properties that make it difficult for tree species to grow

Thermoelectric Properties of Pyrite in the Supra-Ore Level of Gold Mineralization (Ukrainian Carpathians)

The thermoelectric properties of different-aged generations of pyrite from Lostun (Chyvchyny ore region) Tukalo and Kamin-Kliovka (Лостунь, Тукало, Камінь-Кльовка) (Rakhiv ore region) ore manifestations are investigated. The research included traditional geological observations with the collection of samples of various hosting ores, together with mineralogical analysis measuring their reflective power and the thermo electro-motive force of pyrite. Two pyrite generations (pyrite I and pyrite II) have been revealed by the investigation’s results. The crystals belonging to the generations differ morphologically quite vividly (pyrite I has the form of a pentagonal dodecahedron, while pyrite II takes the form of a cube) and have different thermoelectrical properties. Pyrite I testifies to the fact that in the direction from the central parts of crystals with a pentagonal-dodecahedron tendency to its surface, the thermoelectrical properties essentially change. In particular, the central parts of pyrite I crystals have electron conductivity while its faces are mainly hole ones. Such essential changes of the pyrite thermoelectrical properties from the central parts of the crystals to their peripheral ones are probably mostly caused by quantitative changes of element admixtures in the crystalline lattice. However, the pyrite II thermoelectrical properties investigation results testify that this mineral has only hole-conductivity. Thus, in terms of general thermo-e.m.f. (electromagnetic field) as well as selections range, the thermoelectric properties of the pyrite from the Lostun and Tukalo ore manifestations and the Sauliak (Сауляк) auriferous deposit are similar. The comparative character of the pyrite thermoelectric properties from the investigated ore manifestations, the Sauliak deposit and other auriferous deposits testify to the supra-ore level of the gold mineralization in Tukalo and Lostun objects and make it possible to assume that erosion shear of the gold mineralization in Tukalo ore manifestation is similar to the Sauliak deposit erosive shear and is deeper in comparison to the Lostun ore manifestation.

Structural-material model of gold deposit location in the Central Kolyma region

Research subject. Several gold deposits, including superlarge (Natalka), large (Pavlik and Degdekan) and a number of smaller ones are located in the Central Kolyma ore region, near the Ten’kinsky deep fault. The similar position in the recumbent fault flank and confinement to upthrust-thrust plumage faults are characteristic of these objects. The differences are in the position at the different levels of the Permian section, the scale of mineralisation, and some characteristics of the material composition.Materials and methods. An analysis of the spatial characteristics of ore-bearing disturbances was carried out taking into account the change in the angles of their incidence along the section of the enclosing strata. In addition, the composition of the ores, the parameters of fluids and the regular changes in their thermodynamic characteristics were studied.Results. The additive hydrothermal column is restored, in the lower part of which the Rodionovskoye deposit is located, followed by the Degdekan and Natalka deposits, and ending in the upper part by the Pavlik deposit. The total vertical span of such a column is more than 5 km. This structural model explains the trends in the material characteristics of ore-forming fluids, reflecting the variability of the P-T characteristics from bottom to top in the hydrothermal column.Conclusions. The occurrences located directly in the zone and near the ore-supplying Ten’kinsky fault are relatively small in scale; the feathering ore-bearing reverse-thrust structures at a distance of 2–5 km from it are more favourable. Based on this model, a large-volume deposit similar to the Natalka might be located below the Pavlik deposit, which is the upper part of the column.

Geology and pyrite-polymetallic mineralization of the forecasted
 Limonite deposit, Rassokhinsky ore cluster (Yenisei ridge)

The development of Russia’s largest Gorevskoye leadzinc
 deposit (Gorevsky GOK, Novoangarsky OK) will
 depend on promising deposits of the Angara polymetallic
 ore region, in particular, those of the Rassokhinsky
 ore cluster. Based on the analysis of geological and geophysical
 information of previous and current studies,
 a major Limonite pyrite-polymetallic (massive sulfide)
 deposit is forecasted within it. The main lithological
 and stratigraphic criterion for the localization of ores is
 determined by their confinement to high-carbon black
 quartz-sericite schists of the upper subformation of the
 Potoskuy suite of the Upper Riphean. In the top of this
 pack, layered and massive pyrite-polymetallic ores, 70–
 140 m thick, are localized. Based on PPA data, lead and
 zinc content in core varies from fractions of a percent
 to several percent, based on the ICP-AES method: 0,1–
 3,7 % Pb, 0,1–6,4 % Zn, Pb : Zn ratio is 1 : (1–10).

Выделение сквозных структур на основе линеаментного анализа: на примере территории Ферганской долины

As a result of the stress state of the lithospheric block, a structure of orthogonal cracks may appear as a network of straight or arcuate topographic elements of the regional extent on the Earth’s surface—lineaments. In the last decade, one of the directions of lineament analysis had been the identification of the so-called transverse structures using remote sensing methods, which often serve as the geological boundaries of crustal blocks. Various lineament analysis methods are being actively developed: image enhancement, manual digitizing methods, and automatic extraction using software and algorithms. Revealing the relationship between lineaments and their characteristics with natural and anthropogenic processes is the relevant task. The tectonic lineament network is associated with deep faults and, in particular, ore regions that can be localized at the intersection of large lineaments. Therefore, most studies of increased accumulation of lineaments are carried out in areas where mineral deposits and groundwater deposits are identified. These areas include the Fergana region, which is one of the five oil and gas regions of the Republic of Uzbekistan. The presence of a fund of promising traps justifies the need for comprehensive geoinformation support, including satellite methods, and the possibility of transition to automatic methods for analyzing tectonic processes. Therefore, in this study, an automated lineament analysis was carried out in order to identify and interpret the transverse structures in this region. The study period (May–November 2019) was chosen to take into account the intensive exploration work in the region and the technical parameters of the images (without clouds). Landsat 8 satellite images were processed by the automated method of lineament structures interpretation in the LEFA program in the MATLAB environment. During the visual analysis of the processed images, it was identified that there was a temporary change in the number of lineament structures by month. At the same time, the northwestern part of the region (Namangan region) is characterized as the zone of the strongest manifestation of lineament structures. Further detailing of the lineament structures in terms of direction and orientation made it possible to determine the transverse structures. Thematic maps with the geospatial location of transverse structures showed that the nature and clarity of transverse structures varied depending on the features of the geological structure of the sections they intersected.

ГЕОХІМІЧНІ ОСОБЛИВОСТІ РУДНО-ПОРФІРОВОЇ МІНЕРАЛІЗАЦІЇ У МАГМАТИЧНІЙ СИСТЕМІ ГОШГАРЧАЙ (МУРОВДАРСЬКИЙ РАЙОН, АЗЕРБАЙДЖАНСЬКА ЧАСТИНА МАЛОГО КАВКАЗУ)

The geochemical features of intrusive rocks and the surrounding rocks associated with porphyry copper mineralization in the Goshgarchay magmatic system were studied. Major factors of concentration of copper and copper-porphyritic mineralization in rocks of gabbro-diorite-granodiorite formation has been revealed. It has been established that the structure of this ore region was formed as a result of successive alteration of some deformation stages accompanied by development of fractures in intrusive massive, by dike intrusions, locks displacements along faults and the fractures composed of various mineral associations. Main ore components were defined and relations hips among elements were considered. Geochemical associations allowing the localization of the development area of mineralization have been analyzed in various formation stages of porphyry copper system according to the results of cluster analysis. In this study, Cu, Mo, Pb, Zn, Ag, Ni, Co, Mn, Ti, Cr, V, and Sr both in the surrounding rocks and in ore-bearing intrusive rocks were considered as stable elements. This group of elements can be regarded as indicator elements in porphyry copper. The results of the claster analysis show that the elements which are less characteristical for hydrothermal solutions (Mn, Ti, Cr, V, Sr) keep their freedom in all wallrocks and the existence of their grouping is probably associated with their transportation process from silicate rocks with surrounding basic-average content. The elements such as Cu, Mo, Ag, Pb and Zn which form free group are connected with the generation from the magmatic source in the course of crystallization differentiation process and exposure of rocks to the hydrothermal activity which is considered the source of these elements.The identification of reasons of the association of V with Cu and Zn and Pb with Fe group elements in the intrusive facies rocks is characterized with its uncertainty. The analysis of the schedule made according to the results of Cu and basic ore components (Mo, Ag, As, Bi, Gd, Co, Cr, Se, Ge, Li, Nb and etc.) in the ores of Goshgarchay deposit show their dependence on one another equally. The amount of Cu in the ores have Ag, As, Bi, Cd, Ce, Ge, Sr, Mo, Sb, Th and Ti positive correlation relationship, but it has negative correlation relationship with Co, Cr, Cs, La, Li, Pb, Rb, Ni, Nb and Zn. Direct dependence is observed for ore mass between concentrations of Cu, Mo, Pb, Zn, Ag, Se, Te and other elements in the Goshgarchay porphyry copper deposit. Three various mineral associations differing from one another participate in stock work type copper-porphyry mineralization: 1) primary sulfide minerals; 2) oxidized ores; 3) primary sulfide minerals significantly enriched with products of hydrothermal ore carrying solutions.

Перспективы развития минерально-сырьевых ресурсов крупнейших горнорудных предприятий в кратко-и долгосрочные периоды их деятельности. Часть II: хром, бокситы

Based on stock and published materials, the article reveals some potential of the earth's interior of the Republic, showing the possibility of expanding the mineral resource base of existing mining enterprises by re-evaluating and re-evaluating near-surface and searching for new deposits of medium and deep depths. In the future, the creation of new territorial industrial complexes in some ore regions of Kazakhstan on the basis of approved reserves and predicted mineral resources is not ruled out. It is noted that: for copper, in addition to porphyry copper, there are great prospects for identifying cuprous sandstones and shales; according to the iron-estimation, numerous geological and geophysical anomalies are insufficiently or not studied at all, which have prospects for the search for deposits of both small, medium and large depths; in a chrome way, it is recommended to perform a reinterpretation of materials on the area of a large number of outcrops of ore bodies, collapses and ore occurrences and consider them as criteria for prospecting for either deep deposits or placers; for bauxite raw materials, significant reserves are predicted in areas of known deposits and ore occurrences, certain reserves can be identified in deposits of mining and mining and chemical raw materials and, most importantly, analyze materials on depressions with coal deposits, under which large and super-large (unique) Al2O3 resources, as well as pay special attention to non-bauxite aluminum raw materials, where the researchers predicted billions of Al2O3 reserves. It is concluded that existing and newly created enterprises will be provided with raw materials for many years.

ПЕРСПЕКТИВИ ПРОМИСЛОВОЇ РУДОНОСНОСТІ ПРОЯВУ МІДІ ЖИРИЧІ

Based on the analysis of geological exploration materials, geological and economic reassessment of the copper ore occurrence in Zhyrychi (Volyn ore region) was carried out, including the recalculation of reserves and unproved resources. As it turned out, during the exploration process, the reserves and unproved resources were significantly exaggerated, which misleads potential investors. This was primarily due to the wrong interpretation of the geological structure of the deposit, shape and size of ore bodies. The considerable horizontal length of ore bodies, which at a thickness of 1–3 m extend for several kilometers (up to 4–5 km), raises great doubts. In our view, they are represented mainly by lenticular bodies of relatively short length (the first tens up to the first hundreds of meters). According to our calculations, the unproved resources of copper of category P1 are 220.4 thousand tons, which is four times smaller than in the relevant exploration materials. Reserves of copper of category C2 and the unproved resources of precious metals should be excluded from the calculation as unreasonable and unreliable. The calculation of technical and economic indicators of copper-ore occurrence in Zhyrychi indicates the weak economic efficiency of its probable operation, which should be taken into account when considering investing in this object.

Structure of the Erdenet ore district according to gravimetric data

The purpose of the study is construction of a model of the upper crust structure of the ore region in Mongolia and the three-dimensional mapping of intrusive bodies with which copper-porphyry mineralization is associated. An areal gravity survey was carried out with an observation density of 1 point per 6 km2 with the measurement accuracy of ±0.8 mGal. As a result, it was found that copper-molybdenum ore occurrences of the area including the Erdenet ore district are confined to local gravitational minima, which are interpreted as thickening of the body of the Selenga granitoids. The latter are confined to local depressions of this body base. The spatial proximity of supply channels of small ore-bearing intrusions and large granitoid bodies of the Selenga complex has been established. Porphyry ore intrusions are confined to rather wide (about 10 km) zones located above the depressions of the base of all intrusions of the Selenga complex (both granitoid and diorite). Since the local base depressions of the granitoid intrusions correspond to the position of magma supply channels, ore-bearing small intrusions were introduced approximately in the same places where the supply channels of granitoid intrusions of the Selenga complex existed. Therefore, it can be assumed that this case is characterized by not only tectonic inheritance (confined to the same faults and their intersection points), but also by a genetic one, since residual melts of the same foci, in which intrusion magma of the Selenga complex was generated might be the sources of small intrusions. From this point of view, the expediency of distinguishing an independent Erdenet complex seems to be controversial. Geophysical data on the spatial proximity of specified intrusion supply channels permit only to raise the question of such expediency. The solution to this issue is possible on the basis of a comprehensive analysis of petrological and geochemical data.

ГЕОДИНАМІКА УРАНОВОРУДНИХ ПОЛІВ ЗАХІДНОЇ ЧАСТИНИ ІНГУЛЬСЬКОГО МЕГАБЛОКУ УКРАЇНСКОГО ЩИТА

The Ingul megablock of the Ukrainian Shield contains a number of endogenous deposits of the sodium-uranium formation, which have been developed for more than 55-60 years. With the exception of the Kirovograd uranium ore region, the deposits of which are controlled by discontinuities in the fault zone of the same name, the Vatutinske and Novokostiantynivske ore fields occupy positions within the Novoukrainsky granite-gneiss dome and in close proximity to the later geostructural formation, the Korsun-Novomyrgorod pluton. Paying attention to the high degree of saturation of the Ingul megablock with endogenous uranium deposits, it is emphasized that they also contain an increased content of thorium minerals and, in combination with uranium, they produce ascending gas flows of radon. Therefore, studies of the dynamics of the upper horizons of the lithosphere and the closely related dynamics of the hydrosphere (underground and surface), as well as the gas sphere, are especially relevant both in the regions of uranium ore fields and in areas adjacent to mining enterprises. Beyond the direct influence on the radioecological situation of uranium mining enterprises, special attention should be paid to the study of the dynamics of the lithospheric surface, including fault-block structures and the kinematics of ruptures, affecting the spread of groundwater and, as a result, surface waters contaminated with uranium in the environment. In the areas of uranium ore fields, the kinematic characteristics of disjunctivals contribute to a more correct forecast of radon accumulation in natural weakly insulated underground decompressed structures and the accumulation of more long-lived products of its decay Po, Bi, and Pb with long periods of removal of biological objects from organisms. It is emphasized that in the mine workings of mining enterprises, the technological process is accompanied by nitrate pollution of groundwater due to the use of nitrate-based explosives. Thus, for the predictive assessment of radiation and nitrate pollution of the environment of industrial sites of mining enterprises and adjacent territories, the technological process of which also affects the dynamics of the litho-hydro- and gas sphere, the structural-geological, paleogeomorphological, lithological, hydrogeological, hydrographic and topographic features of the Vatutinske and Novokostiantynivske uranium ore fields. The directions of the advancement of the groundwater fronts from directly uranium mines to the nearest drains have been established. The levels of uranium pollution of surface and underground (well) waters within the Novokostiantynivske uranium ore field, as the most promising for increasing uranium mining in the coming decades, have been determined. The proposed areas and terms of complex radioecological monitoring of the Novokostiantynivske uranium ore field in order to take preventive measures to prevent the withdrawal of existing local recreational areas and water areas into the category of ecologically hazardous. On the example of the Novokostiantynivske uranium deposit, as one of the richest endogenous deposits in Ukraine, through the production shafts, which is planned to rise to the surface of uranium ore from the same type of deposits of the uranium ore field of the same name (Lisne, Litniy and Dokuchaivske) by transporting it by main drifts, the proposed optimal complex of geodynamic studies in the system of radio and general ecological monitoring of the state of the environment of such territories.

Morozkinskoye gold deposit (southern Yakutia): age and ore sources

The paper presents the results of the comprehensive isotope geochemical (Re-Os, Pb and δ34S) study of sulfide mineralization of the Morozkinskoye deposit. The ore zones of the deposit are localized in the syenite massif of Mount Rudnaya, which is located within the Central Aldan ore region (southern Yakutia). Gold mineralization is represented by vein-disseminated or vein type mineralization and is manifested in acidic low-temperature metasomatites – beresites (Qz-Ser-Ank-Py). For the first time we obtained an age estimate of the gold mineralization ~ 129 ± 3 Ma, which the synchronism of the hydrothermal ore process in the beresites, which formed the Morozkinskoye deposit, and magmatic crystallization of the syenites of Mount Rudnaya (~130 Ma). The osmium initial isotopic composition of the studied sulfides indicates a mixed mantle-crustal source of sulfide mineralization. New lead isotopic data of syenites indicate the predominance of mantle lead and an insignificant role of the lower – crust lead, while the isotopic composition of pyrite denotes the presence of the upper crustal material in the ore genesis. The sulfide δ34S values vary from –2.3 to +0.6 ‰ and indicate a predominantly magmatic source of sulfur in the ores.

Mineralogical and petrographic characteristics of the host rocks of the Pervaya Rudnaya Gorka Fe-skarn ore occurrence

The article discusses the mineralogical and petrographic features of the metamorphic formations of the poorly studied and promising the Pervaya Rudnaya Gorka Fe-scarn ore occurrence (Kongor ore region), localized in the Voikar, and the typification of host rocks by mineral composition. In order to clarify the ore-forming affiliation of the Pervaya Rudnaya Gorka ore occurrence, the comparative analysis was carried out with the reference to well-studied Novogodnee-Monto Au-Fe-skarn deposit (Toupugol-Khanmeishor ore region), which showed similar mineral composition, structural and texture features and geological structure of ore objects. According to the results of studies, a close composition of the enclosing volcanic-sedimentary rocks, in particular the skarn formations, containing the gold-sulfide-magnetite mineralization at the Novogodnee-Monto ore deposit; connection with the same intrusive complexes (Sob, Kongor, and Musyur) and faults of the north-western direction. Using the microscopic method of research, the changes in the propylite formation area at the Pervaya Rudnaya Gorka ore occurrence, indicating a large-scale regional pre-ore metasomatism, were first identified and described in detail. The following metasomatic zonation (from the inner to the outer zone): actinolite + epidote chlorite + actinolite + epidote chlorite + epidote was been established at the ore field. Based on the obtained research results, it is concluded that the poorly studied territories of the Polar Urals are promising.