The Bawsaing lead-zinc-silver deposit is located 22 km north of Heho, in the Taunggyi region of the southern Shan State in the east of the Republic of the Union of Myanmar. Stratiform mineralization is localized in several horizons of the Lower-Middle Ordovician carbonate strata of the Wunbye Formation. The ore bodies have a lenticular shape in section with a thickness of tens of meters, a width of up to several hundred meters, and a length of up to the first kilometers. Massive sulfide ores are accompanied by disseminated ones from above and below. The ores are composed of galena, sphalerite, and pyrite with an admixture of chalcopyrite and silver-bearing gray ores. The gangue mineralization is represented by calcite, dolomite, quartz, and barite. In plan, the ore bodies are localized in several northwest-trending linear zones up to 15 km long. The dipping angles of the ore bodies increase from 14° through 53° to a depth of 120 m. The ore-bearing rock members were folded into simple anticlines and displaced by steeply dipping normal faults and low-amplitude strike-slip faults. Primary sulfide and oxidized anglesite-cerussite ores are mined at the ore deposit.
Efficiency of Terra/ASTER satellite multispectral data as applied to forecast of porphyry copper mineralization under conditions of the thick sedimentary and dense vegetation cover was assessed on an example of the Kraichikovo occurrence (Middle Urals). Direct application of the mineralogical indices yielded only the patterns controlled by landscape and anthropogenic factors, which was consistent with the global experience. At the same time, it was demonstrated that the interfering factors were effectively suppressed using the principal component analysis (PCA) technique. The key components identified were PC4 (marking fault zones and bedrock exposures) and PC6 (representing a direct indicator of Al–OH containing metasomatic alterations). The ore-controlling structure was detailed by means of the lineament analysis. A map of ranked prospectivity with new target areas was synthesized based on integrating of the PC6 and PC4. Reasons for the success of the method (extraction of weak, statistically independent spectral signals) and its limitations (anthropogenic noise) are discussed. The results of the research confirm practicability of the adaptation of the PCA-based ASTER interpretation techniques for earlyphase exploration at overcovered territories within the temperate zone.
Generalization of results of a long-term study of the placer gold mineralogy of the Nyartayu and Khobeyu rivers and their tributaries has made it possible to identify a primary gold-bearing potential of the area. The following minerals have been identified in the alluvial heavy mineral concentrate samples: native gold, native bismuth microinclusions, bismuth tellurides and sulfotellurides, and maldonite (Au2Bi). Primary sources of the placer gold are considered to be represented by mineralized rocks of Precambrian age, that provide a bedrock for the identified placers. A proximity of intrusions and of their associated metasomatic halos gives reason to expect a discovery of magmatic-hydrothermal type mineralization of Late Vendian-Early Cambrian age, regenerated during the Late Paleozoic collisional stage. The obtained results of the research are of both scientific and practical interest, as they may contribute to development of prospecting technique improvement.
Data on transportability of kimberlite minerals with increasing distance from their primary source are presented. It is argued that the degree of mechanical processing of kimberlite indicator mineral grains is the most reliable criterion for determining their transport distance. In contrast, determining the transport distances with the use of grain size distribution alone is called into question because of a close relationship of the percent ratios between the kimberlite mineral size classes to the hydrodynamic conditions. Specific recommendations are presented for quantifying the transport distance of kimberlite indicator minerals relative to the primary source. A comprehensive graphical model is proposed for the dependence of the kimberlite minerals preservation degree on their transport distance. It is demonstrated that since kimberlite minerals wear is a function of the transport distance, the presence of rather significant quantities of their "fresh" grains and of completely worn minerals in the same aureole cannot be attributed to the same source.The use of the comprehensive diagram of the distribution of garnets and picroilmenites of varying preservation degrees depending on their transport distance will contribute to increasing the diamond prospecting efficiency.
The Poputninskoe gold-sulfide deposit is the largest one in terms of mineral reserves in the southern Yenisei Ridge. The deposit is controlled by the Mamonsko-Rybinsky fault and confined to the axial part of the Rybinsky horst-anticline, in association with metaultrabasic rocks. The ores are hosted by talc-carbonate-chlorite schists that represent products of metamorphism of the metapicrobasalt-basalt association. The mineralization is related to zones of metasomatites and veinlet silicification; the ore bodies are lensoid-ribbon-shaped zones of crushing and schistosity. Gold is irregularly distributed; a weathering crust of up to 10–60 m thick is developed. The primary ores contain 3.4–11.2 % sulfides and are subdivided into two geochemical types: Au-As (in dolerites and carbonaceous schists) and Au-As-Sb-Cr-Ni-Co (along the basic metavolcanics contact). Native gold is fine-grained, high-fineness; 40–60 % of the gold is associated with sulfides. The results can be used in metallogenic forecasting and prospecting for new gold deposits in the Yenisei Ridge.
Based on results of the field and laboratory studies within the Verkhnetatarskaya gold-bearing area (South Yenisei ore district), four sequentially formed mineral complexes have been distinguished and characterized: 1) gold-quartz (native gold (960 ± 20 ‰), quartz, albite, cummingtonite, almandine); 2) reduced intrusion-related gold (native gold (900 ± 20 ‰), pyrrhotite, arsenopyrite, native bismuth, hadleyite, maldonite, and an unnamed mineral Bi3Te2); 3) alkaline phlogopite-arfvedsonite-feldspar metasomatites with niobium mineralization; and 4) muscovite-quartz-tourmaline greisens. The temperature, pressure, and composition of the mineral-forming solutions have been determined for each complex based on fluid inclusions. Probable sources of the ore-forming material are indicated.
This article considers the results of a study of the mineral composition of the main productive molybdenite-quartz association of the Zharchikhinskoye molybdenum deposit and presents new data on the crystallization time of the granites hosting the ore mineralization. Two U-Pb isotope dates (LA-ICP-MS method) were obtained for zircons from the brecciated and massive granites: 282±3 Ma and 281±3 Ma. The main ore mineral is molybdenite; secondary molybdenum minerals wulfenite, powellite, and ferrimolybdite form under supergene conditions. It was established that the ores of the deposit are characterized by the absence of tungsten minerals and the presence of non-commercial beryllium, polysulfide, and aluminum fluoride mineralization. Based on the study of fluid inclusions in quartz and fluorite, homogenization temperatures were established in the range from 245 to 402 °C. Taking into account the pressure data of 1255–1372 bar, the range of calculated temperatures for the FI capture is 538–554 °C. The ore-forming solutions had relatively low salinity, on the order of ~5.7–11.7 wt. % NaCl equiv. The main salt components are represented by iron and magnesium chlorides.
The Buruktal nickel and cobalt deposit, the largest in Russia, is located in the Orenburg Region and is confined to the weathering crust of the ultramafic massif of the same name in the southern portion of the Buruktal synclinorium. Nickel and cobalt in ores of the deposit are predominantly concentrated in serpentine and montmorillonite group minerals, as well as in magnetite, goethite, hematite, and chlorite. The average nickel grade is 0.86 % and that of cobalt is 0.09 %. The composition of the Buruktal ores was compared with ores of nickel-bearing weathering crusts in other countries. The data obtained were used to determine the weathering crust profile type in accordance with the international classification. Because of the high nontronite content (up to 13 %), relatively low iron oxide and hydroxide content (12 %), along with the higher serpentine content (27 %), the Buruktal deposit cannot be classified neither as a silicate weathering crust, nor as clayey one. Therefore, it is classified as a mixed, clayey-silicate type, which stronly complicates selection of the beneficiation technology.
Based on the results of modeling of aero-hydrodynamic regime in the area of transportation and secondary concentration of the foam product of copper ore flotation, approaches to optimizing the design parameters of column pneumatic flotation machines have been selected. To remove grains of nonmetallic minerals mechanically deposited in the foam layer, it is proposed to achieve maximum "discharge" of excess inter-bubble fluid. Visiometric studies using mineral luminophores have established patterns of secondary concentration processes. The dependences of the mass fraction and extraction of copper into concentrate on the density of the water-mineral fraction of the foam product were determined. The calculation results show that the required duration of the secondary concentration process is provided when the height of the foam transportation zone is from 1.2 to 1.5 m. Designs of column flotation devices with an average foam chute arrangement which ensure stabilization of the aero-hydrodynamic regime and equal-speed unloading of the foam product are proposed. The selected design parameters of column pneumatic flotation machines have been tested and recommended for use in a new series of devices of the KFM series.
The Yuzhno-Magnetitovoye deposit is located in the Eravninsky district of the Republic of Buryatia and localized in a sequence of volcanosedimentary rocks and is confined to a mineralized zone of crushing and brecciation near syenite and dolerite dikes, where vein-veinlet quartz and disseminated sulfide mineralization is developed and lens-shaped bodies of magnetite ores are present. Secondary metasomatic alterations, including propylitization, argillization, and silicification are developed, as well as skarns revealed at deeper levels. Approximately 30 mineral species were identified in the ores, the principal ones being magnetite, hematite, chalcopyrite, and pyrite. The minerals of the oxidation zone are cuprite, covellite, idaite, iron hydroxides, and native copper. Based on ore composition studies and mineral geothermometry, it has been established that the Yuzhno-Magnetitovoye deposit formed in three stages: the skarn, hydrothermal-metasomatic, and supergene ones. The geological features, mineral composition of the ores, and the isotopic and geochemical characteristics of the Yuzhno-Magnetitovoye deposit allow us to assine it to the gold-skarn type.
Skarn-related gold deposits are widely distributed in Kyrgyzstan. These deposits account for about 10% of gold reserves of the country, and they include large deposits with the gold reserves exceeding 70 tons. Three geodynamic settings are distinguished associated with formation of this type gold deposits: early Paleozoic island arcs, Carboniferous active continental margins and settings transitional to collisional, and Permian intraplate tectono-magmatic reactivation. This article characterizes several gold deposits and describes their structural features. A conception of the formation and correlation of large, medium, and small skarn-related gold deposits is proposed. Of important significance for the gold mineralization formation are wallrock metasomatites superimposed on the skarns and their surrounding rocks. A number of the deposits are characterized by the presence of rare and unconventional types of the gold-bearing metasomatites, such as quartz-feldspar ones and hydrothermal (aposkarn) serpentinites, that serve as the prospecting guides and criteria for gold mineralization in areas of distribution of skarn-type ore deposits.
Within the Southern Mongolia, the South Gobi gold ore belt stretching in the sublatitudinal direction for almost 1000 km is the most promising in terms of ore gold. Several gold ore regions are distinguished within its boundaries, the most significant of which are the Oyu Tolgoi, Kharmagtai, OlonOvoot, Dayangar, Manlai, and Tsagaan Suvarga ones. In the eastern segment of the belt, within the MandalOvoot terrane, the Olon-Ovoot ore region is distinguished with different-age hydrothermal-metasomatic gold ore mineralization of various types, represented by the Olon-Ovoot, Khurimt-Khuduk, Itgel, and UnegenDel ore deposits. The maximum potential for gold reserves in Southern Mongolia is related to gold-copper porphyry deposits comprised into the Oyu Tolgoi and Kharmagtai ore regions. In the Oyu Tolgoi ore region, the Oyu Tolgoi ore field is exclusively highly estimated. It comprises seven individual ore deposits that contain in total more than 42 million tons of copper and 1850 tons of gold with fairly high grades. The ore mineralization is genetically associated with quartz monzodiorites and alkaline basalts of the Late Devonian. To the east of the Oyu Tolgoi region, the Tsagaan Suvarga ore cluster is distinguished with the Tsagaan Suvarga molybdenum-copper porphyry type deposit and several ore occurrences. They are characterized by rather low gold (0.08 g/t) and silver (2 g/t) grades. The gold-copper porphyry deposits of the Kharmagtai ore district located 160 km northeast of the Oyu Tolgoi deposit have a great potential for gold reserves. The main Au-Cu porphyry mineralization is concentrated in the Kharmagtai ore field and is associated with porphyry systems of the Kharmagtai igneous complex. Resources of the ore field are estimated at 1.1 billion tons of ore, 37 million tons of copper, and 1.3 thousand tons of gold. In general, the South Mongolian metallogenic province can be considered one of the world richest ones in terms of ore gold reserves. The most significant in this region are the gold-copper porphyry deposits located in the Oyu Tolgoi and Kharmagtai ore regions.
The article considers hetero-ore-bearing regional permeable zones identified by the author in rocks of the plate complex of the East Siberian Platform. A geological and genetic model of these ore-bearing zones is proposed. Recommendations are given for carrying out geological forecasting and prospecting at a scale of 1 : 200 000 to 1 : 50 000 and (or) geological and minerogenic mapping at the same scale within the limits of the Udzha, Billyakh-Tyrkanda, and Angara hetero-ore-bearing permeable zones described in the article. It is indicated that it is possible to identify ore deposits of precious, rare earth, and rare metals in the known diamond-bearing metallogenic zones of the East Siberian Platform, in addition to the fields of diamond-bearing kimberlite pipes.
The gold ore-bearing potential of the Early Cretaceous Arctic orogenic belt of the Far Eastern Arctic is characterized. The gold mineralization is represented by the Au-quartz vein, Au-sulfide disseminated in folded and crushed zones, Au-Bi (gold-rare metal) vein-veinlet and skarn types; by the shallow-depth Au-jasperoid and Au-Ag epithermal types; as well as by the gold-bearing porphyry copper type. The crustal origin of the mineralization is shown based on the S-isotope data on ore sulfides of the objects considered. The maximum prospects are related to the late-orogenic Au-sulfide disseminated mineralization. The Mastakh, Alpha, and Onkuchan gold deposits in the northern frame of the Kular Dome; the Taamar deposit in the Ulakhan-Tas sector; and the Elveney deposit in Chukotka are very favorable for identifying large objects of the Maiskoe type. It is necessary to evaluate the prospects for post-orogenic AuAg epithermal mineralization in the Kular area, as well as Au-jasperoid and porphyry copper types. A need in developing a special program within the framework of the forecasting minerogenic investigations for the coming years is highlighted.
This article summarizes data on altered wall rocks of lead-zinc and polymetallic-VMS deposits confined to carbonate and aluminosilicate rocks in the Priargunskaya metallogenic zone. Geological features of the ore deposits were previously described in a number of publications, but no detailed characteristics of the wallrock alterations were there provided. The authors consider necessary to fill this gap, because the altered rocks represent an important prospecting guide for hidden mineralization of this type. The authors have collected all available data on altered wall rocks at lead-zinc deposits of the Priargunsky region, that were accumulated over the past century. New data on this topic were obtained from the operated Noyon-Tologoy ore deposit associated with volcanic rocks. The previous researchers, when studied the altered wall rocks in the carbonate and aluminosilicate environments, came to conclusion on their formation in the course of beresitization. In this case, different beresite facies form in rocks of different composition: beresites and listvenite-like rocks form in the aluminosilicate varieties, while quartz-ankerite metasomatites form in the carbonate rocks. A study of these rocks at the Noyon-Tologoy deposit (in aluminosilicate environment) led researchers to the same conclusion. The aim of this article was to demonstrate that the assumptions made earlier have been confirmed. Accordingly, the metasomatic facies (beresites and listvenite-like rocks, developed after aluminosilicate varieties, and quartz-ankerite ones, after the carbonate rocks) are considered a prospecting guide for lead-zinc and polymetallic-VMS type mineralization.
The article presents results of the work for diamonds, base and precious metals, fulfilled in the Russian Federation under the "declaration principle" licenses since the mechanism came into effect. The key aspects of amendments in its regulatory framework are demonstrated. Information is provided on the actual financing of geological exploration; the dynamics of applications for and issuance of licenses; and the increase in reserves of diamonds, base and precious metals. Some specifics of the mechanism implementation with respect to primary gold deposits are considered. Some specifics of the geological exploration effectiveness during the mechanism implementation for primary gold are detailed in terms of its reserves increase dynamics; the history of geological exploration of the objects put into the state balance; and the comparative assessment of these objects with respect to the quantity of the mineral reserves, average gold grade in the ores, and the reserves categories with other ore deposits first recorded in the state balance, whose geological exploration was carried out on other grounds for issuing the licenses. Conclusions on the implementation of the "declaration" licensing mechanism for DBPM are presented.
The paper provides a brief description of mining operations at ore deposits that extract inclined thin veins with a low mechanization level. Because of the limited space, only portable pneumatic perforators are used in the faces, and low-performance scraper hoists are used for loading and delivering the ore. To extract ore reserves at such objects, a mining operation system is proposed in which the inclined position of the veins is used for delivering the ore mass from the faces down to the haulage drift under its own weight along a low-friction decking (made of high-molecular-weight polyethylene). If such explosive delivery of the ore mass along a "slippery" decking will be implemented, it is possible to significantly increase the overall level of mechanization of the mining operations due to the use of monorail complexes, productive drilling equipment, and expand the possibilities of using the current rock for backfilling the mined-out space. It is considered that the simplest way to assess the efficiency of the explosive delivery is to use a decking of sheet polyethylene VMPE PE 500 and/or SVMPE PE-1000 when driving an inclined block raise, instead of the scraper delivery.
The geological structural studies substantiate four stages of formation and activation of the fault network of the Southern Ashali gold deposit. Homogenization of fluid inclusions in quartz of the goldlow-sulfide-quartz ores took place at 338…147 °C. The salinity of the fluids varied from 10,5 to 0,3 wt.% with the dominant presence of NaCl and KCl. The sulfur isotope composition of pyrite-I (δ34S = -7 ‰) corresponds to a sedimentary source, and that of pyrite-II and arsenopyrite-I corresponds to a deep-seated source. The U-Pb isotope age determinations (LA-ICP-MS) on zircons from the granitoids 309.1 ± 2.1 and 305.8 ± 2.2 Ma, respectively, and the age of gold-low-sulfide-quartz ores is 280 Ma (Ar/Ar technique). A structural-compositional model of the ore deposit formation is proposed, that comprises six stages: I – sedimentation and early diagenesis; II – late diagenesis and/or metamorphism, associated with the gold-sulfide ores; III – effusive magmatism; IV – intrusive magmatism; V – hydrothermal-I, associated with gold-low-sulfide-quartz type ores; and VI – post-ore hydrothermal-II stage.
The article provides information on the morphology and morphogenesis of minerals from kimberlites and their scattering halos. The principal morphogenetic characteristics of the main kimberlite indicator minerals are discussed in detail. The most common types of microrelief on the minerals, their diagnostic features, and the genesis are described. Physiographic investigations play the basic role in studying the kimberlite minerals from heavy mineral concentrate scattering halos during geological prospecting for diamond. Knowledge of the genesis of the macro- and micromorphology of kimberlite minerals allows one to suggest the physical and chemical conditions of the mineral formation. This helps to reconstruct the succession of stages of the entire mineral assemblage morphogenesis and to trace the history of the scattering halos development. The new information presented may help specialists engaged in prospecting and forecasting for diamond deposits, among other tasks, to determine the genesis of surfaces on the minerals and to clarify their formation conditions. Morphological features of the kimberlite indicator minerals may serve as a chronological reference point that allows to reveal a chronological succession of supergene transformations in the mineral matter.
Possibilities of the infrared microscopy technique as applied to the express diagnostics of diamond crystals and of grains of most of its satellite minerals, extracted from heavy mineral concentrate (HMC) samples, are considered. An original technique of investigation of the diamond satellite minerals with IR-Fourier microscope has been developed. In this case, the spectrum of each sample is recorded, and its identification and determination of the characteristic wave numbers are performed automatically. These parameters are caused by peculiarities of the chemical composition and crystal structure of the mineral and allow one to conclude on its primary sources. Typomorphic properties of kimberlite garnets, olivines, and clinopyroxenes and peculiarities of their IR spectra, that can be used for the prospecting and exploration purposes, are considered on specific examples. It is substantiated that application of the IR Fourier microscopy and of the developed electronic library of spectra of individual mineral grains contributes to increasing the efficiency of the analysis of panned HMC samples in forecasting of and exploration for diamond deposits.
