Ore Minerals Research Articles

Bibliometric and Scientometric Assessment of the Environmental Impact and Sustainability of Open Cast Iron Ore Mining: A Comprehensive Analysis

Bibliometric and Scientometric Assessment of the Environmental Impact and Sustainability of Open Cast Iron Ore Mining: A Comprehensive Analysis

Biomarker signatures and depositional environment of ore-bearing black shale in the Luishia Cu–Co deposit, Democratic Republic of Congo: Implications for regional copper mineralization

The Central African Copperbelt is a globally important sediment-hosted stratiform copper cluster, with regional Cu–Co deposits controlled by Neoproterozoic rift basin. Ore formation in the Copperbelt involves multiple stages of mineralization during diagenesis, basin inversion, and collisional orogeny. Understanding the depositional environment of ore-hosting rocks is crucial for revealing the geological settings and pre-orogenic ore genesis. This paper presents a biomarker study focusing on the ore-bearing black shale in the Luishia Cu–Co deposit, Democratic Republic of Congo. The research investigates thermal maturity, source, and depositional environment of organic matter through rock organic carbon and pyrolysis analysis, chloroform bitumen “A” group component analysis, as well as saturated hydrocarbon gas chromatography-mass spectrometry (GC-MS) analysis. The results indicate significant thermal maturation of organic matter in Luishia black shale. Bacteria are identified as the primary source of organic matter followed by red algae and green algae. The sedimentary environment is characterized by a restricted rift basin under shallow marine conditions with a stratified water column. The processes of bacterial sulphate reduction (BSR) and thermochemical sulphate reduction (TSR) significantly influence the mineralization during diagenesis and basin inversion, respectively. Enhanced thermal maturity promotes methane generation which plays a role in reducing anhydrite and subsequently precipitating ore minerals. The findings have important implications for regional exploration strategies.

Metallogenic model of the Amensif Zn-Pb-Cu-Ag±Au-Bi carbonate replacement deposit (Western High Atlas, Morocco): New litho-structural and mineralogical data

Purpose. In this paper, we discuss the genetic model and emphasize many pending issues on the carbonate replacement textures of the Amensif Zn-Pb-Cu-Ag±Au-Bi deposit (the Western High Atlas, Morocco), the source of metal and the possible contribution of the Azegour granite to this ore genesis. Methods. This study is based on geological mapping, drill core and petrography analysis in combination with ICP-AES, XRD, and SEM data. Findings. The detailed mineralogy consists mainly of sulfides and sulfosalts. The main ore minerals include arsenopyrite, pyrite, sphalerite, chalcopyrite, galena and bismuthinite. Mineral inclusions related to isomorphic sulfosalts are found in galena and/or chalcopyrite. They include matildite, galenobismutite, pavonite, cosalite, schirmerite, krupkaite, ramdohrite, wittichenite, emplectite, luzonite, gustavite, hedleyite, krennerite, wittite, freibergite, tetrahedrite, tennantite and native bismuth. The supergene minerals are anglesite, covellite, malachite, azurite and goethite. In addition, specific replacements are observed between dolomites and sulfides, indicating an interaction between hydrothermal fluid and host rocks. Four ore stages have been identified based on the relationship between mineral phases and ore-forming conditions. The results of this study indicate that Ag and Au precipitation is controlled by the Bi-Te-Pb-S system, while enrichment in Bi, Te and Se sulfosalts and Bi-telluride indicates a magmatic source of the ore-forming fluid. Originality. The study delves into the genetic model of the Amensif Zn-Pb-Cu-Ag±Au-Bi deposit in the Western High Atlas, Moroc-co, with a focus on carbonate replacement textures, while also exploring its classification as either a carbonate replacement deposit or a skarn deposit. Practical implications.Mineral textures are indicators of the replacement process in the Amensif Zn-Pb-Cu-Bi-Ag±Au carbonate replacement deposit (the Western High Atlas, Morocco). The results obtained from this research paper can be used as a powerful tool in mineral exploration of the Western High Atlas.

Lithological and geochemical characteristics and sedimentary environments of the Cambrian high-carbon deposits in the east of the Siberian platform (Kyulenke river basin)

Relevance. The need to study high-carbon deposits as potential sources of hydrocarbons and ore minerals that can significantly increase the mineral resource of Russia. In addition, the analysis of lithological and geochemical features and the reconstruction of the sedimentation conditions of the Kuonamka Formation make it possible to more accurately judge the nature of the Lower and Middle Cambrian paleobasin in the east of the Siberian Platform. Aim. To identify lithological and geochemical features of the composition and determine the sedimentation environment of the Kuonamka Formation. Object. High-carbon deposits of the Kuonamka Formation uncovered by exploration wells on the eastern margin of the Mun arch of the Siberian platform in the Kulenke river basin. Methods. Lithological description of core material; mineralogical and petrographic analysis; X-ray diffraction, X-ray fluorescence and microelement analysis; determination of the content of sulfur and iron forms by wet chemistry; scanning electron microscopy using X-ray spectral microprobe; analysis of petrochemical modules. Results. It was established that the Kuonamka Formation in the studied sections has a consistent structure of four well-defined lithological-stratigraphic horizons. The composition of the deposits is predominantly mixed and is determined by variations in three main mineral groups: clay, carbonate and siliceous, in addition organic matter. The paper demonstrates different forms of organic matter confirming the mixed algal-bacterial genesis of the biocenosis of the Kuonamka basin. The revealed lithological features and lithochemical data indicate the accumulation of high-carbon deposits at a considerable distance from the drift sources in the depression zone of the open sea basin with weak circulation of bottom waters in anoxic conditions. The geochemical euxinic environment was dominant in carbonate-siliceous muds. Sedimentation occurred during one major transgressive-regressive sedimentation cycle being a typical sequence of filling a uncompensated deep depression.

Characterizing low-grade refractory gold ores using automated mineralogy coupled with LA ICP-MS

Researchers have made notable progress in quantifying refractory components causing gold losses in traditional extraction methods. The potential for improving gold recoveries lies in targeted re-treatment of the 'invisible' gold fraction hosted within various ore minerals, even at low concentrations. This study presents a methodology for analysing the refractory components that cause gold losses in traditional extraction methods. The approach utilizes automated mineralogical techniques in conjunction with in-situ laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) to characterize low-grade refractory ores and assess gold deportment. The methodology combines pre-concentration gravity separation, traditional chemical and mineral techniques, and LA ICP-MS to generate comprehensive datasets. To demonstrate the practical application of the methodology, a case study was conducted on historical tailings material from Witwatersrand's Evander Goldfield in South Africa. The case study aimed to determine the mineralogical distribution of gold that cannot be extracted through cyanidation. The results indicated that invisible gold is primarily hosted in pyrite (with an average concentration of 10.21 ppm representing 32 % of total gold), other sulphides (with an average concentration of 1.29 ppm representing 0.42 % of total gold), and oxides (with an average concentration of 0.50 ppm representing 1 % of total gold). The remaining gold is present in discrete fine cyanide amenable phases (with 28 % deportment) and silicate-hosted phases (with 39 % deportment). Environmental monitoring of the Witwatersrand tailings material revealed a net “acid-producing” nature, with high concentrations of heavy metals (such as As, Cu, Pb, Mn, Hg, and Ni) associated with sulphides (with over 78 % deportment). The deportment information obtained through this approach can optimize ore processing strategies and provide valuable insights for future remediation plans. By characterizing the refractory components causing gold losses and understanding the distribution of gold within the ore, this methodology offers the potential to enhance gold recovery and improve the efficiency of ore processing operations.

Porous durian shell biochar modified by KMnO4 (Mn-DSB) as a highly selective adsorbent for Be(II).

The mining of uranium-beryllium ores has resulted in substantial beryllium (Be) contamination. In this study, agricultural waste durian shells were utilized as raw materials to prepare biochar, which was further modified to enhance its adsorption capacity (Mn-DSB). The results effectively demonstrated Mn loading onto the DSB surface. Batch experiments were conducted to identify the optimal adsorption conditions of Mn-DSB for beryllium. At a temperature of 35 °C and pH 6, beryllium's maximum adsorption capacity (Qe) was 42.08 mg·g-1. The materials' internal structure was analyzed before and after adsorption via multiple techniques. Mn-DSB manifested potent selectivity towards beryllium in multicomponent mixed solutions, binary systems, and uranium-beryllium wastewater, as the beryllium removal rate exceeded 90%. The study investigated the recyclability of Mn-DSB and found that after five reuse cycles, the adsorption and desorption efficiencies were 90% and 85%, respectively. The strong ligand complexation (N-H, CO32-, -OH) and ion exchange mechanisms (with Mn7+ ions) of Mn-DSB explained its high adsorption capacity. Therefore, this study demonstrates the potential of Mn-DSB for treating uranium-beryllium tailing wastewater.

Geological structure and metallogeny of Precambrian sedimentary structures of western Aldan-Stanovy Shield

The article presents the results of the study by various geologists of the geological structure and prospects of ore-bearing trog complexes performing structures such as throgs, which were identified at different stages of geological research in the western part of the Aldan-Stanovy shield. The main types of traction complexes and their sections were determined. The nature of the occurrence of sedimentary (terrigenous), volcanogenicsedimentary and metavolcanic rocks performing throgs and forming throg complexes was established. The nature of the ratio of these rocks in the context of the trog complex in the studied trogs was described. The results of the study of trog complexes showed that they are generally characterized by facies variability, heterogeneity of metamorphism and dynamothermal processing of rocks (especially in the sides of trogs) with the formation of mylonites and cataclasites. It was established that the throgs are confined to three regional systems of discontinuous disturbances. Both consonantal and secant discontinuities were marked inside the throgs, defining their block tectonics. The results of determining the geological age of the rocks of the trogovoi complex were presented. The trog structures are characterized by ore mineralization associated with the processes of sedimentation (ferruginous quartzites, copper sandstones) and volcanogenic ore formation (copper-crusted and polymetallic mineralization), as well as with the processes of metamorphogenic-hydrothermal redistribution of ore matter (stratiform scheelite mineralization, ore-bearing quartz veins). It was also found that the metallogeny of the trog structures has not been studied sufficiently. Nevertheless, the majority of geologists who studied the trogovye complexes noted in their reports that Precambrian trogovye complexes can be considered as important and metallogenically promising geological objects in the western part of the Aldan-Stanovy Shield and deserve more in-depth study.

Implikasi Putusan World Trade Organization terhadap Larangan Ekspor Nikel Indonesia oleh Uni Eropa

Indonesia as a member of the World Trade Organization (WTO) is bound by the General Agreement on Tariffs and Trade (GATT) and WTO regulations. In an effort to increase domestic raw material processing, Indonesia implemented an export ban on nickel ore and other minerals. However, this action sparked protests from the European Union, leading to a lawsuit filed with the WTO. This article analyzes the WTO decision in the context of international trade principles, examining its legal applicability in Indonesia and its impact on other types of minerals. The research method used is a normative legal approach or doctrinal research. The final decision of the WTO dispute settlement panel declared that Indonesia's policy of export bans and mandatory processing of nickel minerals violated Article XI.1 of the GATT 1994. Nevertheless, Indonesia appealed the decision and remains committed to the nickel ore export ban to advance the economy and welfare of its people. Thus, this policy represents a bold step towards downstream the mining industry.

Collaborative separation of nickel and iron from nickel laterite ore and red mud

ABSTRACT In this study, we investigated a nickel laterite ore with Ni content of 1.56 wt% and a red mud with Fe content of 20.98 wt%, the main Ni-bearing mineral in the nickel laterite ore was nickel-lizardite, and the main Fe-bearing mineral in the red mud was hematite. A novel process of roasting and magnetic separation was purposed to extract nickel and iron from the nickel laterite ore and red mud. The nickel laterite ore, red mud, calcium chloride, and coke were mixed and put in a roaster for roasting, and the ferronickel concentrate was obtained from the roasted ore by magnetic separation. The results showed that a ferronickel concentrate with Ni content of 7.97 wt%, Fe content of 73.09 wt%, iron recovery of 76.87%, and nickel recovery of 90.28% was obtained under the optimal conditions: a mass ratio of m (nickel laterite ore): m (red mud) : m (coke) : m (calcium chloride) : of 0.6:0.4:0.2:0.1, a roasting temperature of 1373 K, a roasting time of 90 min, a grinding fineness of − 0.045 mm occupying 90%, and a magnetic field strength of 0.20 T. The main minerals in the ferronickel product were metallic Fe and FeNi.

Formation of Intergrowths of Platinum-Group Minerals and Gold from Magmatogenic Ores in Relation to Phase Changes in Pt-Pd-Fe-Cu-Au System

The article discusses the features of the chemical composition and the formation of intergrowths of platinum-group minerals, gold, gold-bearing phases, and other ore minerals present in placers collected from the Anabar River in the northeast part of the Siberian platform. Based on an analysis of changes in the phase compositions of these intergrowths of noble metals with other ore minerals on (Pt, Pd)-Fe-Au and Pd-Cu-Au phase equilibrium diagrams, potential trends in the crystallization of natural polymineral alloys from multicomponent low-sulfide metallic liquids are discussed. The similarity of the microstructures of natural and metallurgical alloys indicates that the formation of natural multiphase Au-PGE intergrowths occurred in a similar manner to the crystallization of multicomponent synthetic alloys. The authors suggest that magmatic Au-PGE mineralization occurs during the crystallization of a noble-metal-containing, low-sulfide, Cr-rich oxide melt separated from silicate mafic–ultramafic magma. Magmatic gold–platinum deposits are commonly associated with sulfide or oxide disseminated-schlieren ores in layered mafic–ultramafic intrusions. However, due to the high solubility of gold and platinoids in sulfide minerals, PGMs in sulfide ores occur as isomorphic impurities or as microphases and dispersed inclusions that cannot form placers. Therefore, the authors suggest that magmatic Au-PGE mineralization occurs during the crystallization of an immiscible low-sulfide, high-Cr oxide liquid separated from silicate mafic–ultramafic magma. In the northeast part of the Siberian platform, potential sources for these placers are likely alkaline, high-Ti mafic–ultramafic intrusions, as confirmed by the presence of silicate inclusions in ferroan platinum similar in composition to melteigite.

Adding Agricultural Topsoil and Growing Perennial Ryegrass (Lolium perenne L.) Enhanced the Rehabilitation of Metal/loids Enriched Iron Ore Mine Tailings

Revegetating iron-ore mine tailings is difficult due to their poor physicochemical and microbial properties. This experiment aimed to improve tailings properties for better plant growth and rhizosphere activities. First, a pot experiment was conducted to assess the influence of topsoil amendment on the remediation of tailings collected from two sites (coded A and B) in Western Australia to promote the growth of perennial ryegrass (Lolium perenne L. cv Ausvic). Each pot was filled with pre-defined ratios of topsoil to mine tailings (0, 10, 20, 30, 50 and 100% w/w). Perennial ryegrass was harvested 60 days after sowing and analysed for plant growth, root morphological characteristics and metal uptake by shoots. Second, a study on biological attributes and an incubation study over 84 days were carried out. The addition of topsoil significantly decreased pH, but EC and total organic carbon (TOC) increased with an increased proportion of topsoil. Total concentrations of As, Co, Cr, Cu, Ni, Pb, Zn, Fe and Mn decreased with an increased ratio of topsoil in growth medium. The highest root dry biomass was observed in the treatments with 30% and 50% topsoil addition to tailings, whereas shoot dry biomass only increased with 50% topsoil. Total root length increased significantly with 50% topsoil addition to site A tailings. A significant increase in microbial biomass carbon (MBC) was found with 50% addition of topsoil compared with the control. Microbial quotient (MBC/TOC) decreased significantly with the addition of topsoil to both types of tailings. Metal contents in perennial ryegrass shoots decreased with the increasing rate of topsoil, but perennial ryegrass was an effective phytoextractor of Cu, Zn and Mn. Further, the incubation study revealed that 50% topsoil application increased cumulative respiration emissions in both A and B tailings after 42 days. Iron ore mine tailings can be improved in terms of physicochemical and biological attributes by adding topsoil. However, further investigation should be carried out to determine the speciation of metal/loids in amended iron ore tailings.

Health risk assessment of soil heavy metals in a typical mining town in north China based on Monte Carlo simulation coupled with Positive matrix factorization model

The accumulation of heavy metals (HMs) in soil caused by mineral resource exploitation and its ancillary industrial processes poses a threat to ecology and public health. Effective risk control measures require a quantification of the impacts and contributions to health risks from individual sources of soil HMs. Based on high-density sampling, soil contamination risk indexes, positive matrix factorization (PMF) model, Monte Carlo simulation and human health risk analysis model were applied to investigate the risk of HMs in a typical mining town in North China. The results showed that As was the most dominant soil pollutant factor, Cd and Hg were the most dominant soil ecological risk factors, and Cr and Ni were the most dominant health risk factors in the study area. Overall, both pollution and ecological risks were at low levels, while there were still some higher hazard areas located in the central and south-central part of the region. According to the probabilistic health risk assessment (HRA), children suffered greater health risks than adults, with 21.63% of non-carcinogenic risks and 53.24% of carcinogenic risks exceeding the prescribed thresholds (HI > 1 and TCR>1E-4). The PMF model identified five potential sources: fuel combustion (FC), processing of building materials with limestone as raw materials (PBML), industry source (IS), iron ore mining combined with garbage (IOG), and agriculture source (AS). PBML is the primary source of soil HM contamination, as well as the major anthropogenic source of carcinogenic risk for all populations. Agricultural inputs associated with As are the major source of non-carcinogenic risk. This study offers a good example of probabilistic HRA using specific sources, which can provide a valuable reference for strategy establishment of pollution remediation and risk prevention and control.

3-D imaging of whole-space environments with electromagnetic induction sensors based on linear approximation

Accurate mapping of the periphery of tunnel has become an essential step in underground mining and engineering. Because of high sensitivity to electric conductivity and magnetic permeability, the whole-space electromagnetic (EM) method has played an important role in geological forecast of groundwater and exploration of mineral ore. However, obtaining a three-dimensional (3-D) image of the whole-space EM method by 3-D inversion is challenging due to the limited observation space and inefficiencies in 3-D forward modeling algorithms. While 1-D inversion algorithms have long been used to map the periphery of the tunnel, various 3-D inversion algorithms have been successfully applied in other scenarios. Recently, the portable frequency domain loop-loop EM induction (EMI) measurement has been considered as an active source magnetic method in near surface surveys, because of the dominance of magnetic permeability in the in-phase (IP) response. The 3-D linear forward modeling method is developed based on the location-specific magnetic sensitivity function, and the 3-D inversion algorithm has been effectively employed for mapping magnetic anomalies in large-scale area. In this study, we intend to demonstrate that the EMI measurement can give 3-D image of the periphery of the tunnel by theory and numerical experiments. The IP response of EMI in whole-space is separated into three parts, and the 3-D linear forward modeling method is examined by analytical solution. The 1-D Fourier transform is used to accelerate the 3-D forward modeling, and the 3-D inversion show a good performance of mapping the magnetic abnormal bodies in underground space.

Оперативное измерение горной массы в процессе погрузочно-доставочных работ

The article discusses an automated control system for underground mining of copper-nickel ores and the weight control system as a part of this system. The main functions of the weight control system are described, as well as the requirements towards this system, the principle of applying the proposed algorithms and the results of implementing this system at an existing mining operation. The experience of measuring the rock mass during loading and hauling operations is described in terms of operational management and control of actual quantitative and qualitative parameters of ore flow in the multistage process of the ore grade stabilization in underground mining. The obtained results help to solve the challenge of controlling the LHD bucket load while ensuring the required parameters and operating conditions for the following application scenarios: (1) control of the transported rock mass for each haul cycle with the accuracy of ±6%; (2) control of the transported rock mass by a particular LHD per shift with the accuracy not worse than 1% for 60 haul cycles per shift; (3) for the operations with high moisture content of the transported load, it is possible to account for the stuck material for each haul cycle; (4) no special requirements to the weighing process; (5) minimization of the operating costs for calibration and maintenance; (6) high reliability due to minimum amount of hardware; (7) no degradation of the method when using readings of the hydraulic system; (8) unification of the system. The accuracy and reliability of the data obtained gradually increases during the operation when the test measurements are made about once a month. The disadvantages include: (1) impossibility to use the metrological level for measurements; (2) dependence on the technical condition of the onboard hydraulic system; (3) partial dependence on the LHD mileage. A conclusion is made that the process of ore grade stabilization should be multistage, and the measurement of the rock mass during the loading and hauling operations is one of the mandatory methods for implementation of the geometallurgical tasks.

The Geology and Geochemistry of Kakafu Pegmatites: An Investigation for Lithium Ore Bearing Minerals (Lepidolite-Spodumene), Pategi North Central Nigeria

The preliminary investigation of the Kakafu pegmatites was conducted, with the aim of carrying out detail geological mapping and geochemical analysis to reveal common field and geochemical features that will lead to understanding the nature of the Kakafu pegmatites, for the purposes of identifying its lithium minerals potential. Geological mapping reveals three lithological units in the area, which includes; muscovite schist, biotite granite and pegmatite veins. Mineral composition observed in the field and as hand specimen are quartz, plagioclase and orthoclase feldspars, muscovite, biotite and tourmaline. Also the two lithium minerals recognized by the investigation; lepidolite and spodumene (kunzite) grades vertically with depth and along the veins in areas where the veins swells. The main lineament features (fractures, joints and folds) observed trends in the NE-SW, NW-SE, N-S and E-W directions, these directions correspond with orientations of the pegmatites in the study area. Geochemical plots of K vs Rb; K/Rb vs Rb; Li2O vs SiO2 and Ca O vs SiO2 show linkages amongst the pegmatites of the study area. Also the plots of A/CNK vs SiO2 and TiO2 vs SiO2 show all the pegmatites samples fall in the fields of S-type and igneous protolith respectively. These linkages amongst the Kakafu pegmatites suggest they are genetically related to one another, and have same origin (igneous protolith). In terms of mineral potential assessment, the plots of A/CNK vs SiO2; Li2O vs SiO2 and REE show that the Kakafu pegmaites are strongly peraluminous and hence potential for lithium ore mineralization. Furthermore, the concentrations of Li2O of Kakafu pegmatites ranges between (0.82-2.27wt%) and averagely all are above 1wt%. This suggests the Kakafu pegmatites to be moderately potential for lithium ore mineralization.

Effect of OHS Criteria on Selection of Concrete Additives in Mine Ore Construction Works

Construction, mining or tunneling projects in Türkiye are defined as workplaces in the very dangerous class due to their physical power needs. For this reason, metal ore mining, mining supporting service activities, sewage, external construction, special construction activities, construction and landscaping activities are the sectors where occupational accidents are most common. While determining the necessary materials or work equipment during the planning phase of the works in these sectors, making decisions by evaluating the effect of "occupational health and safety" will contribute to the reduction of accidents. This research consists of two parts. In the first part, accident frequency rates were calculated by using data related to metal ore mining, mining supporting service activities, sewerage, external structure, special construction activities, building and landscaping projects between 2012 and 2019. Thus, the relationship between occupational accidents experienced as of the adoption of the Occupational Health and Safety Law has been determined. In the second part, it is tried to gain a different perspective by adding occupational health and safety factor to the Analytical Hierarchy Process (AHP), which is one of the multi-criteria decision-making methods. As a result of the research, it has been determined that "occupational health and safety" criteria are given priority according to cost and engineering advantages in alternative product/material comparisons in mines or construction works.

Nanoparticle depressants in froth flotation – The effect of colloidal silica with different size and surface modifications on the selective separation of semi-soluble salt type minerals

Colloidal silica has been presented as a selective depressant in froth flotation separation of scheelite and calcite by our group in 2020. Here we analyze the effects of colloidal silica dosage, specific surface area (i.e. size), and modification with microflotation on pure scheelite, calcite, fluorite, and apatite minerals. In a reagents scale-up procedure batch flotation experiments were conducted on a low-grade scheelite ore using statistical experimental design methodology. Microflotation experiments showed colloidal silica selectively depressing calcite flotation with increasing intensity with reduced size of colloidal silica. The nanoparticulate depressant did not affect the recoveries of scheelite, apatite, and fluorite – typical ore minerals that occur associated with calcite. Batch flotation of a low-grade scheelite ore confirmed the observations made at the microscale: colloidal silica significantly improves the scheelite-calcite selectivity index. Here, we observe a series of relations between colloidal silica specific surface area and modification on different process indicators such as scheelite-calcite selectivity index, recoveries, and froth properties. These relations are assumed to be due to the different aggregation mechanisms of the colloidal silica dispersions. The aluminate-modified colloidal silica, which tends to form a coherent gel network in the presence of Ca2+, shows the strongest effect on reducing calcite recovery accompanied by a significant reduction in scheelite recovery compared to the non-functionalised and silane-modified colloidal silica.

A special ore formation of the newly discovered Hamaling Au-Cu-Mo polymetallic deposit in the Tongling ore-cluster region: Constraints from geochronology and geochemistry

The Hamaling deposit represents the first discovery of a gold-copper-molybdenum deposit situated within the Ordovician strata of the Tongling ore-cluster region. It comprises three distinct types of ore, including porphyry-type Cu-Au ore found in granodiorite, skarn-type Cu-Au ore at the contact zone, and breccia-type Mo-Cu ore within the Ordovician strata. However, the exact mineralization age, ore genesis, and mineralization processes of the Hamaling deposit remain uncertain. To address these uncertainties, the present study employed LA-ICP-MS to date zircon in granodiorite and garnet in skarn, revealing ages of 139.3 ± 0.44 Ma and 142.3 ± 0.89 Ma, respectively. Additionally, the age of 140.0 ± 1.1 Ma was obtained through Re-Os dating of molybdenite from breccia-type ore. These findings suggest a connection between the Hamaling deposit and the early Cretaceous magmatic activity in the Tongling region. The granodiorite intrusion exhibits a high-potassium calc-alkaline affinity and formed under oxidized conditions at temperatures ranging from 721 to 832 °C (average 769 °C). The Hf isotope composition of the granodiorite implies its formation through the mixing of mantle-derived magma from an enriched lithospheric mantle with partially melted lower crustal source magma. The sulfur isotopes found in the ore minerals range from δ34S = 5.55 ‰ to 11.99 ‰, indicating a magmatic sulfur source. The H-O isotopic compositions of quartz during the quartz-sulfide stage suggest that the magmatic water was the primary component of the fluids responsible for ore formation, possibly with some contribution from meteoric water. The identification of the Hamaling deposit highlights the significant potential for mineral exploration within the Lower Paleozoic strata in the Tongling ore-cluster area and even the broader Middle-Lower Yangtze River Valley Metallogenic Belt (MLYB).

The role of polyphase deformation in the formation of iron deposits and gold mineralization in the paleoproterozoic nyong complex greenstone belt (Southwestern Cameroon)

The Toko-Nlonkeng area is situated in the Nyong Complex of the northwestern Congo craton. In this study, airborne geophysical data (radiometric and magnetic) and structural data (outcrops and core samples) were used to investigate the relationship between structural evolution, iron formation (IFs)-hosted iron ore deposits, and gold mineralization in the Paleoproterozoic Nyong complex greenstone belt in southwestern Cameroon. Magnetic and radiometric trends, combined with field data, show general NE-SW, NW-SE, and E-W directions that correlate with the main gold-bearing structures. The study area has undergone four (04) deformation phases relating to polycyclic metamorphic and magmatic events. The D1 and D2 phases are the result of progressive ductile and transpressional deformation; D3 is a brittle-ductile deformation; and D4 is essentially brittle with various types of fracture networks late to post-orogenic. The D3 deformation phase is characterized by constrictive deformation with C3 shears and meso‑ to mega-P3-folds, and the main stress axes show φσ2 > φσ1> φσ3, reflecting a shearing tectonic regime with a maximum E-W shortening. This polyphase deformation is derived from the Eburnean/Trans-Amazonian deformation related to the collision between the Congo and São Francisco cratons. The main strain in the structural style of the Nyong Complex appears to be transpressive tectonics. This study reveals that iron ore and gold mineralization were mostly found on the hinges of folds and confirms that folding shear zones controlled the iron ore and gold target in the Nyong Complex and Northeast Brazil. The study proposes an approach to optimize future exploration activity based on the integration of the data.

In-situ analysis of sphalerite trace elements and sulfur isotope of the Zhaxikang Pb-Zn-Sb-Ag deposit in southern Tibet: Implications for source and mineralization process

The metallogenesis of collisional orogen has been a significant research topic for comprehending the linkage between magmatism, metamorphism, hydrothermalism and ore deposition. In Southern Tibet, the Zhaxikang deposit is a super-large Pb-Zn-Sb-Ag polymetallic deposit with metal reserves of 2.367 Mt Zn + Pb (average grade of 6.43 %), 0.2552 Mt Sb (average grade of 1.14 %), and 2960.6 t Ag (average grade of 101.64 g/t), constituting the largest deposit within North Himalayan Metallogenic Belt. However, the metal sources of the ore-forming material and mineralization process in this deposit remain a subject of controversy due to previous studies primarily relying on a bulk analysis of sulfides, which record the mixed results of multistage mineralization and intergrown minerals of different stages. The objective of this study is to constrain the sources and mineralization process of the Zhaxikang deposit through in-situ analyses of trace elements and sulfur isotopes in sphalerite. Based on ore textures and mineral paragenesis, four mineralization stages and three generations of sphalerite deposited respectively in stage 1 (Sp1), stage 2 (Sp2), and stage 4 (Sp3), were identified. The Pb and Zn mineralization mainly occurred in stage 2, while Sb and Ag were dominantly in stage 4. The trace elements characteristics (Cd, Fe, In, Ga, Ag, Cu, Co, and Mn) observed in sphalerite indicate that the Zhaxikang deposit could be a hydrothermal vein-type deposit associated with magmatism. The δ34S values of sulfides (7.7–18.4 ‰) in the deposit generally exhibit a slight elevation compared to those (4.1–12.9 ‰) of the Jurassic Ridang Formation slate, indicating that the sulfur of the deposit primarily originated from seawater sulfate in the slate through thermochemical sulfate reduction, although a small amount of contribution from mafic rocks also existed in stage 4. The Pb isotopes in stage 2 range from 19.662 to 19.705, 15.852 to 15.865, and 40.214 to 40.283 for the ratios of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb, respectively, indicating that the metals primarily from the Greater Himalayan Crystalline complex (GHC) with a minor contribution from host rocks. While, the Pb isotopes in stage 4 range from 19.687 to 19.849 for 206Pb/204Pb, from 15.86022 to 15.885 for 207Pb/204Pb, and from 40.261 to 40.414 for 208Pb/204Pb, respectively, indicating that the metals originated from sulfides in the earlier stage as well as the more radiogenic GHC.