Reserves Of Deposit Research Articles

Концепция устойчивого развития горнопромышленного региона Кабардино-Балкарии на основе использования хвостов обогащения Тырныаузской фабрики в закладке выработанного пространства

Introduction. Generalization of the world experience of integrated development of deposits indicates that the solution of the issues of involvement of mining and ore processing wastes in industrial exploitation is an urgent scientific and practical task. Therefore, the article presents the results of research on the possibility of using old tailings of ore dressing of Tyrnyauz tungsten-molybdenum combine (TTMK) to backfilling space in the process of finalization of reserves of Tyrnyauz deposit. Methodology and methods of research. The methods of research are the analysis of data on the formation of tailings of Tyrnyauz enrichment plant, laboratory experiments to study the material and granulometric composition of tailings, thermo-gravimetric analysis of tailings and study of strength properties of mixtures prepared based on tailings. Discussion of research results. The results of tests of samples of backfilling prepared based on initial and burnt samples of old tailings with the addition of different cement and water consumption are shown, which in the dynamics of strength gain testify to the possibility of obtaining the given characteristics of the filling massif in the required terms of its exposure at different thicknesses of ore bodies being finalized and the variants of development systems adopted in this connection. Conclusion. The possibility of preparation of stowing mixtures based on old tailings of Tyrnyauz enrichment plant has been proved. Resume. The choice of a specific composition of solidifying backfill mix will be made depending on the capacity of the deposits to be reworked and the variant of the deposit reserves reworking system determined by it with the use of floorchamber systems of development with two-stage order of reserves extraction in chambers of I and II stages. In addition, the rest of the accumulated reserves of technogenic raw materials in the tailings pond may, if necessary, serve as a resource for backfilling the mine workings at the second stage of development of the overlying reserves of the deposit. Proposals for practical application and direction of future research. The obtained results can be used in development of technological solutions aimed at increasing the efficiency of involvement of technogenic raw materials from tailings ponds and finalization of the main reserves of deposits when using the development systems with backfilling of mined-out space.

Поэтапная комбинированная разработка золоторудных месторождений

Introduction. It is noted that in the Russian gold mining industry, the profitability of gold production is associated with the development of technologies for leaching it from substandard ores and enrichment waste. It is shown that the priority aspect of the development of substandard raw materials is to increase the yield of more gold with acceptable additional investments, predicted based on the analysis of the production function in the models of economic growth of enterprises. The purpose of the study is to substantiate the possibility of increasing the completeness of subsurface use during the phased development of reserves with a combination of chemical and mechanical extraction processes. Methods of achieving the goal include the use of literary and patent sources, production experience, laboratory and field experiments, modeling and technical and economic calculations. Results. The relevance of the development of a new raw material base is shown by the example of the reserves of the Sadonsky poly-metallic deposit. The information on the operations of hydrometallurgical and heap leaching of gold with bringing to the final product is detailed. An algorithm is proposed for the selection of options for the development of gold bulls. A model is presented to calculate the efficiency of phased field development over time. An optimized scheme of heap leaching of gold and indicators of gold extraction are presented. The scheme of electrochemical leaching of gold from sulfur-containing ores is recommended. The factors of the impact of mining on the environment at three stages of development are systematized. A model is presented for determining the efficiency of utilization of enrichment tailings and profits from the extraction of gold from enrichment tailings and metallurgy, taking into account environmental damage. The results of calculating the efficiency of gold extraction at the factory and leaching in blocks and cubes are presented. It is shown that the end-to-end metal recovery coefficient by leaching is comparable to the traditional technology of processing balance reserves. It is proved that when combining technologies at the stages of field development, a larger amount of metal is extracted from the subsurface. Conclusion: with a small increase in infrastructure modernization costs, combining traditional technology and leaching technologies, more metal is extracted from the subsurface.

Опыт применения цифровых геомеханических моделей при освоении рудных месторождений Сибири

The article considers a generalized approach to application of digital models of deposits and organization of geomechanical monitoring systems in the mining of ore deposits in Siberia based on experience of research work carried out by the staff of the Mining Institute named after N.A. Chinakal, Siberian Branch, Russian Academy of Sciences, in the interests of industrial partners. A scheme of managing geomechanical monitoring is given, which provides verification and adaptation of the geomechanical model to the changing conditions of the mined deposit. The results of determining the stress-and-strain state of the rock mass at the Aikhal mine and assessing the state of the ore ceiling are presented. With the use of numerical geomechanical models, a geomechanical justification is made for application of the technology with backfilling of the minedout space. The impossibility of using the mining systems based on caving is demonstrated when extracting the pit reserves of polymetallic mineral deposit. The conclusion provides proposals for organizing geomechanical monitoring with the use of digital geomechanical models.

Geometry and origin of supergiant gold deposits in the Jiaodong gold province, eastern China

Based on the new deep exploration results, the gold reserves of Jiaojia gold deposit and Sanshandao gold deposit of the Jiaodong gold province, eastern North China Craton (NCC), exceed 1300 and 1200 tons, respectively. Both deposits are distributed along adjacent faults of Jiaojia and Sanshandao, respectively, forming a globally significant supergiant deposit. The main orebodies are preserved along two low-angle steps on the faults, with Jiaojia orebodies deposited in left-stepping bends, and Sanshandao orebodies deposited in right-stepping bends. The above geometric distribution of orebodies of these two deposits is clearly related to the kinematics of the ore-controlling faults. Weideshan suite is the largest Cretaceous magmatic rocks in the Jiaodong peninsula, which is considered as a profound impact on the gold mineralization in Jiaodong. LA-ICP-MS U-Pb dating of magmatic zircons from the associated Weideshan suite granitoid yields ages of 121.3 ± 2.1 Ma and 116.7 ± 1.7 Ma, which are consistent with mineralization age of the gold deposits (ca. 120 Ma). On the basis of regional geological data, our study indicates that the large-scale magmatic activities in the Early Cretaceous of Weideshan suite provide thermodynamic conditions for gold mineralization. A metallogentic model suggests that the formation of Jiaodong type gold deposits may have involved a thermal doming-extension process during the Mesozoic decratonization of NCC. In the Early Cretaceous, mantle upwelling and crust-mantle interaction triggered magmatism and fluid activities. These activities were simultaneous with granitoid doming, crustal extension and detachment faulting, upgrading Au of gold deposits. Mantle-derived gold-bearing fluid mixed with crust-derived gold-bearing fluid precipitated from remelting lower crust, forming gold-rich fluid reservoir and producing gold-poor Weideshan suite granitoid. Subsequently, granitoid doming, crustal extension and detachment faulting occurred. This process provides both favorable channels for ore-forming fluid migration and potential locations for enriching and trapping fluids, forming supergiant ore deposits.

Substantiation of the Technology of Refining Gold Reserves at the Zholymbet Deposit

A set of technical solutions for the opening, preparation and clean-up of the reserves of the Zholymbet gold deposit at the stage of completion in order to maintain the production capacity of the underground mine is outlined. The Zholymbet deposit is located in the south-east of the Seleta-Stepnyak Megasynclinorium in the southern part of the Aksu-Zholymbet structural-metallogenic zone. The deposit of the Zholymbetskoye deposit includes 3 sections (Central, Southern, Northern) and a number of manifestations of the gold-quartz formation. The sites lie in the endo- and exocontact parts of Steppe-type intrusions (Central and Southern) and on the rise of the roof of the Sorokkuduk massif (Northern). The gold mining factory is intended for processing ore from the central section of the Zholymbet deposit («Quarry No. 6», «shh. Center»). The production capacity is 500,000 tons of ore per year. The gold content in commercial ore is 3.07 g/t. The peculiarity of this stage is the need to involve ore bodies bordering on previously worked blocks into operation, as well as taking into account the diversity of mining and geological and mining technical conditions caused by a large number of disconnected ore bodies with insignificant reserves. These technical solutions provide timely access to all reserves of the deposit, safety of mining operations, efficient transportation of ore and ventilation of treatment faces. The adopted technical and technological solutions ensure the effective development of all reserves of the field

Selecting the optimal exploitation option using a digital deposit model and the AHP

The prime objective of the study was to identify and evaluate options for development and exploitation of a prospective hard coal deposit using a digital geological model and a multi-criteria decision-making approach allowed, in elaborated research process, to identify investment alternatives and outline the one that maximizes the benefits for the potential investor. The developed research methodology was based on decision criteria including: economic, technical, geological, social, and environmental aspects. The combination of the above criteria made it possible to create six options for the development of the deposit named as: 1.2 MAX and 1.2 EKO, 1.5 MAX and 1.5 EKO, and 1.8 MAX and 1.8 EKO. The Analytic Hierarchy Process (AHP) was used as a method to select the optimum investment option. The research process consisted in taking into account the positive and negative impacts of individual exploitation options by building four separate hierarchical models (BOCR analysis), i.e. Benefits (B), Opportunities (O), Costs (C) and Risks (R).Digital geological model of the existing and prospective deposit was a key source of information for AHP assessment process. The structural model of 15 seams of economic importance and a qualitative model of coal quality parameters were elaborated. The structural and quality models were prepared on the basis of lithostratigraphic profiles from 55 surface boreholes, 16 underground boreholes and 250 geological profiles of mine workings in the area of the existing coal deposit. These models constituted input for the assessment of economic efficiency of the above mentioned options. The digital model served as the basis for the creation of access, development and mining work schedules, and the developed simulations of mining exploitation were used to build a model of surface deformation considered as one of the most significant decision-making factor.The result of the work was formulated as a ranking of the analyzed scenarios, indicating the most attractive ones. In this case, and in terms of the adopted AHP methodology, the dynamic strategy scenarios is represented by ‘No additional shafts' scenario, 1.8 EKO, 1.8 MAX and 1.5 EKO scenarios. Their implementation fulfils the policy of sustainable depletion of the reserves of a prospective deposit, while maintaining environmental standards and high economic efficiency. The ‘No additional shafts' scenario represents the idea of rapid decommissioning of the mining industry, while scenarios 1.8 EKO, 1.8 MAX and 1.5 EKO are in turn scenarios of rational resources management allowing for gradual depletion of the deposit reserves in a long-term perspective.

Mesh Processing for Snapping Feature Points and Polylines in Orebody Modeling

The 3D refinement modeling of the orebody provides an important guarantee for the estimation of the resources and reserves of an ore deposit. Implicit modeling techniques can effectively improve the efficiency of orebody modeling and facilitate the dynamic updating of the model. However, due to the problems of ambiguity and missing features during implicit surface interpolation and implicit surface reconstruction, the mesh models of orebodies obtained by means of implicit modeling techniques do not easily snap to the geological feature points and feature polylines obtained based on geological sampling data. In essence, all models are inaccurate, but geological sampling data are very useful and valuable, which should be accurately and effectively involved in the orebody modeling process. This would help to improve the reliability of resource estimation and mining design. The main contribution of this paper is the proposal of a method for accurately snapping orebody features after implicit modeling. This method enables the orebody model to snap accurately to the geological feature points and feature polylines and realizes the accurate clipping of the model boundary. We tested the method with real geological datasets. The results showed that the method is applicable and effective when the geological feature points and feature polylines are close to those of the orebody mesh model and the shape trend changes little, and the model can thus meet the practical application requirements of mines.

Estimation of fresh groundwater reserves of the Ravnetskoye deposit for water supply to the city of Ishim

Estimation of fresh groundwater reserves of the Ravnetskoye deposit for water supply to the city of Ishim

РАДОНОВЫЕ ВОДЫ БОЛЬШОЙ БЕЛОКУРИХИ: СОВРЕМЕННОЕ ИСПОЛЬЗОВАНИЕ И ПЕРСПЕКТИВНЫЕ УЧАСТКИ РАЗВИТИЯ КУРОРТА

At present, a tourist and recreational cluster is being formed around the federal resort of Belokurikha, which includes the adjacent territories of the Smolensk, Altai and Soloneshensky municipal districts of the Altai Territory. To determine the directions of spatial development in the cluster, information is needed on the prospects for discovering new sources of radon waters. The purpose of the study is to assess the current level of use of radon waters by the resort of Belokurikha, to identify geological and geochemical prospecting indicators of radon waters and to assess the prospects for their detection within the tourist cluster "Bolshaya Belokurikha". A field study of the territory and sampling of granitoids from the Belokurikhinsky pluton were carried out. The analysis of isotopes of uranium and thorium from granitoids was carried out according to the classical method at the Center for Isotope Research of the Russian Geological Research Institute (St. Petersburg). The analysis of the current water use was carried out based on the data of the Hydroservice of the resort of Belokurikha on water consumption for 2019. The volume of radon water consumption by the sanatoriums of the Belokurikha resort in 2019 varied throughout the year from 435.1 m3 / day in August to 282.1 m3 / day in December. This does not exceed the operational reserves of the Belokurikhinskoye deposit, which are 600 m3 / day. Potential areas for the detection of radon waters are confined to the deep sub-latitudinal Belokurikha fault, which runs along the border of the Pre-Altai plain and the Altai Mountains, and especially to the zones of intersection of faults of different directions. This is the main geological prospecting indicator. The geochemical prospecting indicator is the increased content of uranium in rocks. The highest concentrations of 238U and 232Th isotopes in the granitoids of the Belokurikhinsky pluton were found for aplites and pegmatites. Thus, the entire strip of the transition zone from the Biysk-Barnaul depression to the mountain-folded structure of Altai has prospects for radon waters, due to a complex of features for prospecting and factors of water formation with the participation of the vadose component and of deep waters leaching minerals with increased radioactivity from aplites and pegmatites. Prospective sites for carrying out detailed prospecting for radon waters are located in Belokurikha-2 in the area of the village Ulyanovka and near the village of Danilovka. Here, in addition to indirect prospecting indicators, there are also direct ones (radon content in waters).

REY enrichment mechanisms in the early Cambrian phosphorite from South China

Worldwide phosphogenesis during the early Cambrian occurred coevally with localized Rare Earth Element plus Y (REY)-rich phosphorite in Zhijin, South China. Although characteristics of the Zhijin phosphorite have been well constrained, the major factors controlling REY enrichment remain unknown. To address this, the research studied the REY occurrence forms and enrichment mechanisms. Accordingly, carbonate C and O isotopes, micropetrographic, and in situ geochemical analyses of Zhijin phosphorites were conducted. Results show that the phosphates are composed of closely-packed nano to μm-scale apatites, which were spherulitic and short cylindrical, comprising mainly fluorapatites and minor francolites. Element mapping verifies that REYs were hosted in apatites by isomorphous substitution, with minor REY being adsorbed by clay minerals. Further, REY was incorporated into apatite crystals during the early diagenesis according to LaN/SmN vs. LaN/YbN plots. Apatites show Medium REE (MREE)-rich post-Archean Australian shale-normalized distribution patterns, attributed to selective adsorption of MREEs by Fe-/Mn oxides/hydroxides or organic matters. Plots of Nd and Ceanom manifest lower sedimentation rates of REY, providing adequate time for REY absorption in the seawater. Excluding secular variations of REEs in the ocean chemistry, we suggest that constrained paleogeography provided a suitable space for REEs entering apatite crystals during early diagenesis. This is possibly the primary cause for the vast REE reserves of the Zhijin phosphorite deposit. In addition, redox conditions, temperature, biological activities, and weathering played non-critical roles in REY enrichment in apatites. Our findings can inform on multi-factor constraints of REY-rich marine phosphorites in the early Cambrian and provide a further understanding of REY enrichment in worldwide sedimentary marine phosphorites.

Оценка постэксплуатационного состояния вольфрамово-молибденового месторождения и возможности нового его вовлечения в природопользование

Reserves of the main Russian tungsten deposit, the Primorye Field, are close to depletion. In this connection, the feasibility of resuming the development of the Tyrnyauz tungstenmolybdenum deposit in the Kabardino-Balkar Republic (KBR) has been the subject of discussion for the past decade. According to industry experts, the ore field of this deposit still contains about 50% of the total tungsten reserves of the Russian Federation. However, implementation of the idea will be hindered by a number of both external and internal constraints. The world demand for tungsten and molybdenum is characterized with high volatility. Classical mechanisms to regulate the non-ferrous metals market in Russia are still rudimentary. The production infrastructure at the Tyrnyauz Plant has been completely destroyed, which means high capital costs for the project. The abandoned ore fields disturbed by industrial development have undergone serious changes due to intensive geochemical and gravitational processes. This physical and chemical transformation was caused by internal and external conditions which resulted in formation of migratory and toxic aggregates that had not been manifested at the time of the mine closure. As a result, the natural and man-caused evolution of ores and nonmetallic minerals has caused a significant reduction in the balance reserves of this deposit. The final decision regarding this project should be based on comprehensive understanding the obvious risks, which are impossible to avoid. Thus, if the decision is made to build a new metallurgical enterprise, it will then operate in the new market conditions with more stringent requirements regarding the mining and geological parameters of the deposit. Ore extraction and processing are inherently highly energy intensive processes. It is not an easy task to achieve its high profitability under conditions of constant and unpredictable growth in energy prices. Forecast investments to launch a new mining complex with innovative technology are too high; according to various estimates, they may reach 22-29 billion rubles. The generation of specialists who used to work at the mine before the Perestroyka is gone, and it will take years to create a new highly qualified team.

Morphological features of ore reserves of the Novo-Uchaly vms deposit (Southern Urals)

Background. The Novo-Uchaly copper-zinc VMS deposit in the Southern Urals (54°10΄54˝N and 59°20΄45˝E) is represented by a steeply dipping lens of Eifelian volcanics (rhyodacites and basalts), which are crumpled into a strongly compressed anticlinal fold. The ore deposit is blind and localised at the convergence of felsic (bottom) and mafic (top) rocks. The deposit is located at depths of 550 m (in the northern part) and 1050 m (in the southern part). The deposit thickness reaches 186 m. The length along the strike and along the dip equals 1250 m and 900 m, respectively. The ore body is intruded by gabbro-diorite and gabbro-diabase dikes. The main ore minerals are pyrite, sphalerite and chalcopyrite, as well as non-metallic minerals, such as quartz, barite and calcite. Unlike most of the Ural VMS deposits, this deposit is the zinc subtype (Zn >> Cu). The ores are predominantly massive and solid sulphide, being banded or brecciated in some parts. The main elements extracted are copper, zinc and sulphur, but gold, silver, cadmium, indium, cobalt, nickel, selenium and tellurium are also obtained.Aim. To clarify the morphology of the ore deposit, to study the ore mineral composition of the upper horizons of its northern part and to determine the underlying reasons for the complex lenticular structure of the sulphide reserve.Materials and methods. In the period 2017—2019, employees of the Institute of Ore Deposits, Petrography, Mineralogy and Biochemistry of the Russian Academy of Sciences (IGEM RAS) together with geologists of the Uchaly Mining and Processing Plant carried out a geological and mineralogical mapping of the deposit in the course of exploration works.Results. The ore contours and mineral composition of the northern part of the ore body were significantly clarified. A series of dikes of variable morphology was identified. A comparison was made of the results with current theories about the structure of the ore deposit. Detailed geological sections were determined and illustrate the complex lenticular structure of the ore deposit complicated by pinch and swell areas. The deposit was formed by processes of dynamic metamorphism.Conclusion. The geological and mineralogical structure of the deposit determined in the study enabled us to propose a schematic reconstruction of the conditions leading to the formation of its folded structure. The findings will help to re-assess the reserves and improve the system of operational exploration and delineation.

Разработка остаточных запасов Кумакского золоторудного месторождения (Оренбургская область)

Разработка остаточных запасов Кумакского золоторудного месторождения (Оренбургская область)

A non-stationary spatial approach to disjunctive kriging in reserve estimation

In the spatial estimation of recoverable reserves of an ore deposit, disjunctive kriging is used to calculate the panel-wise ore and metal tonnage by estimating the conditional probability of block grades. In real mining practice, it is necessary to consider a change of support model along with disjunctive kriging to estimate functions of the variables with larger support than samples. However, disjunctive kriging is based on the assumption of strict stationarity. But, in reality, stationary model often falls short in evaluating complex geological structure. It is obvious that the standard stationary technique neglects the apparent changes in the local mean and variances and hence produces unreliable outcomes. Moreover, important geological feature such as spatial continuity of the deposit does not get replicated by the conventional stationary model. This paper deals with the formalism of a non-stationary disjunctive kriging model allowing change of support model and its practical application in estimating local recoverable reserves of ore deposit. A thorough investigation through simulation experiment is carried out to critically judge the performance of the proposed model followed by a real life application to a copper deposit. The relevance of the developed model is established as it is validated by real production data.

Formation conditions of useful reserves of Nizhnemzymtinskoe fresh groundwater deposit on Caucasian Black Sea coast and their space and time variations under intense anthropogenic load

The formation conditions of the useful reserves at the Nizhnemzymtinskoe Fresh Groundwater Deposit are considered. The deposit is confined to the lower part of the Mzymta R. valley on the Caucasian Black Sea coast. The main source of reserves formation is surface river water. In the previous years, the reserves depended on the development-induced channel deposits colmatage, whose characteristics were used in the evaluation of groundwater reserves since the 1980s using the method of analogy. The intense construction operation in the river valley in 2010–2011 appreciably increased the colmatage of channel deposits, resulting in a decrease in groundwater reserves. The developed space and time model of the deposit made it possible to take into account not only the spatial characteristic of all factors governing the formation of groundwater reserves, but their time variations as well.

Support and Information Effect Modeling for Recoverable Reserve Estimation of a Beach Sand Deposit in India

Application of geostatistics in estimating recoverable reserves of beach sand deposit is rare. This paper made an attempt to estimate local recoverable reserves using disjunctive kriging and discrete Gaussian model considering support and information effects for a beach sand deposit located in the eastern part of India. The dependence of different selective mining unit (SMU) sizes and different production sampling strategies on the estimated tonnage, metal quantity, and the ore tonnage versus metal quantity relationships has been examined. The results of the study show that nonlinear geostatistics should be used for more precise assessment of the grade, ore tonnage, and metal quantity and their relationships, which are necessary for recoverable reserve estimation. In selective mining operation, both support and information effects have significant influence on recoverable reserve. Recoverable reserve estimation based on SMU involves estimating grade distributions of mining unit with much bigger support than the available drill core sample data. Information effect comes into picture from the real scenario where the actual grades of the blocks remain unknown even during mining. At the mining stage, discrimination of ore and waste blocks is carried out based on estimated grades of the production samples and it is likely that the blocks might be misclassified as either ore or waste and thus sent to wrong destination. Information effect modeling makes the estimation more reliable by taking care of misclassification.

Use of mine planning software for the evaluation of resources and reserves of a sedimentary nickel deposit

The use of mine planning software in the evaluation of deposits and estimation of mineral resources and reserves has become widespread and is considered a prerequisite for the reporting of reserves according to international reporting standards and codes. The main principles of operation and application of these codes are transparency of reported material, the relevance of reported information (materiality) and the competence of people involved in producing the reports. The application of specialised mine planning software described in this paper currently takes place at operational mines of sedimentary nickel deposits in Central Evia, Greece. It involves all stages of processing of exploration data including entry, analysis, processing and modelling of data, geostatistical estimation of quantities and qualities of mineral resources and mineral reserves, and the design, optimisation and scheduling of mining operations.

Research of Extent of Well Control of Explored Reserves of Lithologic Deposit in Delta Front Area

Recently the explored reserves submitted in the oil field mainly situate at the end of deposit in delta front area. During the exploitation and production, problems mainly show on lithologic deposit, for example, reserves are low and difficulty of producing is huge. Based on results of sand body dissection of dense well network of developed oil deposit, and combined with explored reserves, this article researches a relation between extent of well control and reserves precision of explored reserves of lithologic deposit in delta front area by well diluted method. This article has significant influence on objectively understanding our unexploited reserves

Important improvement of utilization the available geological reserves of the South mining district deposit in Majdanpek in the new defined optimum contour of the open pit using the Whittle and Gemcom softwares

A significant increase in copper prices on the World Metal Exchange, whose lower limit in the long term will not be under $ 6,000 per ton of cathode copper, and reduction the operating costs of ore mining by introduction the high capacity mining equipment in the production process, requires a new consideration of the open pit South Mining District Majdanpek and defining the new final (optimum) limit of mining for the given techno economic parameters. Using the modern software tools for strategic planning and optimization of deposit Whittle and software for design the open pit Gemcom, the optimum contour of open pit was designed on the principle of maximum profit realization. In the newly-defined contour of analyzed open pit, significantly higher geological reserves of deposit are affected in relation to the previous considerations of those amounts to the amount of 172,388,652 t of ore with average copper content in the ore of 0.383%. .

Geology, mineralogy, and sulfur isotope geochemistry of the Sargaz Cu–Zn volcanogenic massive sulfide deposit, Sanandaj–Sirjan Zone, Iran

The Sargaz Cu–Zn massive sulfide deposit is situated in the southeastern part of Kerman Province, in the southern Sanandaj–Sirjan Zone of Iran. The stratigraphic footwall of the Sargaz deposit is Upper Triassic to Lower Jurassic (?) pillowed basalt, whereas the stratigraphic hanging wall is andesite. Mafic volcanic rocks are overlain by andesitic volcaniclastics and volcanic breccias and locally by heterogeneous debris flows. Rhyodacitic flows and volcaniclastics overlie the sequence of basaltic and andesitic rocks. Based on the bimodal nature of volcanism, the regional geologic setting and petrochemistry of the volcanic rocks, we suggest massive sulfide mineralization in the Sargaz formed in a nascent ensialic back-arc basin. The current reserves (after ancient mining) of the Sargaz deposit are 3 Mt at 1.34% Cu, 0.38% Zn, 0.08%Pb, 0.24 g/t Au, and 7 g/t Ag. The structurally dismembered massive sulfide lens is zoned from a pyrite-rich base, to a pyrite ± chalcopyrite-rich central part, and a sphalerite–chalcopyrite-rich upper part, with a sphalerite-rich zone lateral to the upper part. The main sulfide mineral is pyrite, with lesser chalcopyrite and sphalerite. The feeder zone, comprised of a vein stockwork consists of quartz–sulfide–sericite pesudobreccia and, in the deepest part, chlorite–quartz–pyrite pesudobreccia. Footwall hydrothermal alteration extends at least 70–80 m below the massive sulfide lens and more than a hundred meters along strike from the massive sulfide lens. Jasper and Fe–Mn bearing chert horizons lateral to the sulfide deposit represent low-temperature hydrothermal precipitates of the evolving hydrothermal system. Based on mineral textures and paragenetic relationships, the growth history of the Sargaz deposit is complex and includes: (1) early precipitation of sulfides (protore) on the seafloor as precipitation of fine-grained anhedral pyrite, sphalerite, quartz, and barite; (2) anhydrite precipitation in open spaces and mineral interstices within the sulfide mound followed by its subsequent dissolution, formation of breccia textures, and mound clasts and precipitation of coarse-grained pyrite, sphalerite, tetrahedrite–tennantite, galena and barite; (3) replacement of pre-existing sulfides by chalcopyrite precipitated at higher temperatures (zone refining); (4) continued “refining” led to the dissolution of stage 3 chalcopyrite and formation of a base-metal-depleted pyrite body in the lowermost part of the massive sulfide lens; (5) carbonate veins were emplaced into the sulfide lens, replacing stage 2 barite. The δ34S composition of the sulfides ranges from +2.8‰ to +8.5‰ (average, +5.6‰) with a general increase of δ34S ratios with depth within the massive sulfide lens and underlying stockwork zone. The heavier values indicate that some of the sulfur was derived from seawater sulfate that was ultimately thermochemically reduced in deep hydrothermal reaction zones.