Zinc Ore Deposits Research Articles

Geological formation conditions for lead and zinc ore deposits in the People’s Democratic Republic of Algeria

Geological formation conditions for lead and zinc ore deposits in the People’s Democratic Republic of Algeria

A Study on The Tectonic Control and Metallogenic Regularity of The Sanjiang Sanjiang Metallogenic Belt Cobalt Deposit in Yunnan Province

The Sanjiang region of Yunnan is rich in minerals, especially known for gold, copper, lead zinc, and iron ore deposits. There are many genetic types of ore deposits, and most of the ore deposits (points) and anomalies are controlled by the northwest north-south structural belt. The regional tectonic activity is strong and the metallogenic conditions are superior. In this paper, the structural ore-controlling effect and metallogenic regularity of Sanjiang Metallogenic Belt cobalt deposit in Yunnan Province are further studied. The mineralization of the ore belt is most closely related to the Caledonian submarine hydrothermal sedimentation, and after mineralization, it was obviously transformed by Indosinian metamorphism and hydrothermal superposition. Some scholars have carried out relevant research on the geological and geochemical characteristics and genesis of the deposit, and think that the deposit is stratabound-reformed, jet sedimentary, hydrothermal sedimentary-tectonic reformed, etc. However, the chemical properties of ductile rocks are inactive and the permeability is poor, which makes the ore-forming fluid difficult to lose, which is beneficial to the full water-rock reaction between minerals in hydrothermal solution and surrounding rocks flowing through carbonate rocks, resulting in a large number of minerals precipitation and enrichment. When the soft and hard rocks alternate with each other, it is beneficial to form bedding detachment structure to become ore storage space, and it is also beneficial to the precipitation of minerals along the chemical interface and the enrichment of minerals.

Feasibility of Simultaneous Application of Fuzzy Neural Network and TOPSIS Integrated Method in Potential Mapping of Lead and Zinc Mineralization in Isfahan-Khomein Metallogeny Zone

Iran is located on a silver, lead, and zinc belt and according to the latest studies holds 11 million tons of lead, zinc, and silver stones which constitute 4 percent of global resources. Considering that mineral materials are explored in an uncertain space, exploration investment risk is an inseparable part of these activities. The important fact is to minimize the effect of this undesired factor in exploration. To achieve this, it is required that exploration activities and withdrawals are performed in a certain framework in which risk minimization is considered. Using mineral potential modelling for determining promising zones which should be taken into consideration in more detailed stages could make achieving the purpose possibly. This work is aimed at applying fuzzy neural network and TOPSIS methods simultaneously in order to explore zinc and lead resources. In this article, geological, telemetry, geophysics, and geochemistry data is integrated using fuzzy-neural network (neuro fuzzy) and using TOPSIS method rating for lead and zinc ore deposit potential mapping in Isfahan-Khomein strip which has been introduced as one of zinc and leads mineral scopes in Iran. This area which is composed of several zinc and lead ore deposits has been considered as the target area. Fuzzy integration results of zinc and lead mineralization witness layers confirm the relatively high potential of lead and zinc mineralization in this region having a northwest-southeast trend and involving more than 90 percent of the known indices and ore deposits of the region. In this research, it was shown that the results of TOPSIS-Neuro-Fuzzy integrated model (a combination of neural network and fuzzy logic) have increased the resolution of talented areas from the areas with no mineralization potential in comparison with the fuzzy method individually.

Determination of the Backfilling Time for the Zinc and Lead Ore Deposits with Application of the BackfillCAD Model

This article introduces a BackfillCAD model that relates to the determination of the backfilling time. The relationship of the individual model modules using a flow chart are characterized and presented. The main aim of the research was to determine the time of backfilling for the prospective deposits of zinc and lead ores in the Olkusz region in Poland. In the first stage of the research, laboratory tests were carried out on the backfilling mixture consisting of sand and water in a 1:1 volume ratio. In the laboratory tests, the content of grains below 0.1 mm, the washability, water permeability, and compressibility of the backfilling mixture were determined. After the standard requirements were met by the backfilling mixture, the arrangement of one-way and bidirectional strip excavations was designed. In the next stages, by means of computer aided-design MineScape software, maximum thicknesses of the ore-bearing dolomite layer (T21_VI) for four geological cross-sections were determined. The height of the first backfilled layer with a thickness of 5 m was analyzed. Taking into account the geometrical parameters of the strip—the maximum length and its width and height, as well as the capacity of the backfilling installation—this study calculated the backfilling times for the future strip excavations.

Selection of the optimal contour of the open pit in mining the lead and zinc ore deposit with the increased mercury content

Mining processes are complex and complicated, with many different economic, technical, environmental and other parameters that must be planned before the project gets its practical value. Many of these parameters are evaluated independently of others, due to the expediency and difficulties in predictting values for variables under consideration. Costs, prices, reserves, mining and processing of ore, as well as many social aspects, such as issuing permits for works, are absolutely crucial for the project evaluation. Each ore body is different, but the main steps in the open pit planning, when the main goal is to maximize NPV, follow the same principle. These steps are presented as the linear for simplicity. The actual planning process is an iterative process, in which some steps or a combination of steps are repeated many times with the sensitivity analysis.

Application of the CSAMT Method to Pb–Zn Mineral Deposits: A Case Study in Jianshui, China

The electromagnetic (EM) method is commonly used in mineral exploration due to the method’s sensitivity to conductive targets. Controlled source audio-frequency magnetotellurics (CSAMT) is developed from magnetotelluric (MT) method with an artificial EM source to improve the signal amplitude. It has been used for mineral exploration for many years. In this study, we performed a case study of the CSAMT application for the Eagles-Nest lead–zinc (Pb–Zn) ore deposits in Jianshui, China. The Eagles-Nest deposit is located in southwest in China in forest-covered complex terrain, making it difficult to acquire the geophysical data. Based on the previous dual-frequency induced polarization (IP) results, we designed four profiles for the CSAMT data acquisition. After data processing and inversion, we mapped the subsurface resistivity distribution. From the CSAMT results, we inferred the location of the ore body, which was verified by the drilling wells. The Pb–Zn ore body was found at a depth between 373.70 m to 407.35 m in the well.

An experimental study on metal precipitation driven by fluid mixing: implications for genesis of carbonate-hosted lead–zinc ore deposits

A type of carbonate-hosted lead–zinc (Pb–Zn) ore deposits, known as Mississippi Valley Type (MVT) deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping with or without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H2S, rather than HS− or S2−, dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.

Metallogenic Epoch of Nonferrous Metallic and Silver Deposits in the Jiaodong Peninsula, China and its Geological Significance

AbstractAs China's most important gold‐producing district, the Jiaodong Peninsula also contains copper, lead–zinc, molybdenum (tungsten), and other nonferrous metal ore deposits, but the space–time and genetic relationships with gold deposits remain uncertain. To investigate the temporal relationship between these nonferrous metal and gold ore deposits, We collected the samples from a number of nonferrous metallic and silver deposits and metallogenetic rock bodies in the eastern Jiaodong Peninsula for isotopic dating. The results show that the Re‐Os isotopic model ages of the Lengjia molybdenum deposit in Rongcheng range from 114.5 ± 1.8 Ma to 112.6 ± 1.5 Ma, with an average age of 113.6 ± 1.6 Ma; the LA‐ICP‐MS 206Pb/238U ages of 33 zircons in the sericitization porphyritic monzogranite that hosts the Tongjiazhuang silver deposit in Rongcheng range between 122 Ma and 109 Ma, with a weighted mean age of 116.04 ± 0.95 Ma; the LA‐ICP‐MS 206Pb/238U ages of 31 zircons in the copper metallogenic pyroxene monzodiorite that hosts the Kuangbei copper deposit in Rongcheng range from 126 Ma to 106 Ma, with a weighted mean age of 116.6 ± 1.7 Ma; and the LA‐ICP‐MS 206Pb/238U ages of 19 zircons in the pyroxene monzodiorite surrounding the Dadengge gold and multimetal deposit in Weihai range from 113 Ma to 110 Ma, with a weighted mean age of 111.7 ± 0.6 Ma. All these results indicate that the metallogenic ages of the silver and nonferrous metallic deposits in the Jiaodong Peninsula are in a limited range from 118 Ma to 111 Ma. Previous studies have demonstrated that the isotopic ages of gold deposits in the Jiaodong Peninsula range from 123 Ma to 110 Ma, while Weideshanian magmatism occurred between 126 Ma to 108 Ma. Both these ranges are grossly consistent with the metallogenic ages of silver and nonferrous metallic deposits in this study, suggesting that the large–scale mineralization occurred in the Early Cretaceous when magmatic activities were strong. This epoch may be linked to the lithosphere thinning and the thermo‐upwelling extension in eastern China at that time. In addition, field investigation also shows that gold and nonferrous metallic deposits are distributed nearby the Weideshanian granite, with the nonferrous metallic deposits lying within or surrounding the granite pluton and the gold deposits outside the granite pluton. We propose the following mineralization scenario: In the Early Cretaceous, an intensive lithospheric extension induced partial melting and degassing of the metasomatized lithospheric mantle, which resulted in the formation of mantle–derived fluids enriched in metal elements. During the rapid process of magma ascent and intrusion, crust‐derived fluids were activated by the magmatic thermal dome and served to further extract ore‐forming materials from the crust. These fluids may have mixed with the mantle‐derived fluid to form a crust–mantle mixing–type ore‐forming fluid. The high‐temperature conditions in the center or in contact with the granitic magmatic thermal dome would have been favorable for the formation of porphyry–type, skarn–type, and hydrothermal–vein–type ores, thus forming a series of Mo(W), Cu, and Pb‐Zn deposits in the mid‐eastern Jiaodong Peninsula. In contrast, the medium‐ to low‐temperature conditions in the periphery of the magmatic thermal dome would have favored the deposition of gold (silver) ores under the appropriate physiochemical and structural conditions. The metallogenic epoch of the molybdenum, copper, and silver deposits, and their spatiot‐emporal and genetic relations to the gold deposits, as demonstrated in this study, not only provide important insights to the study of regional metallogeny, our understanding of the metallogenesis of the Jiaodong type gold deposit, and the geodynamic background of the large‐scale mineralization in the Jiaodong Peninsula, but also have practical value in guiding the mineral exploration.

A review of major non-sulfide zinc deposits in Iran

The numerous non-sulfide zinc ore deposits were the historical basis for the development of zinc mining in Iran. They include the Mehdiabad, Irankouh and Angouran world-class deposits, as well as the Zarigan and Haft-har deposits. These deposits were formed by supergene oxidation of primary sulfide minerals during the complex interplay of tectonic uplift, karst development, changes in the level of the water table, and weathering. Zn (Pb) carbonates, Zn-hydrosilicates and associated hydrated phases directly replace the primary ore bodies or fill cavities along fractures related to uplift tectonics. Direct replacement of primary sulfides is accompanied by distal precipitation of zinc non-sulfide minerals in cavities or internal sediments filling. The mineralogy of the non-sulfide mineralization in all six deposits is generally complex and consists of smithsonite, hydrozincite, and hemimorphite as the main economic minerals, accompanied by iron and manganese oxy-hydroxides and residual clays. Commonly, non-sulfide minerals in these deposits consist of two types of ore: red zinc ore (RZO), rich in Zn, Fe, Pb-(As) and white zinc ore (WZO), typically with very high zinc grades but low concentrations of iron and lead. Typical minerals of the RZO are Fe-oxyhydroxides, goethite, hematite, hemimorphite, smithsonite and/or hydrozincite and cerussite. Common minerals of the WZO are smithsonite or hydrozincite and only minor amounts of Fe-oxyhydroxides and hemimorphite.

Features of Shaimerden Deposit Oxidized Zinc Ore Leaching

The object studied is Shaimerden oxidized zinc ore deposit containing zinc, lead, copper, iron, calcium, magnesium, aluminum, manganese and silicon. Chemical and mineralogical composition of the ore are investigated. It is established that ore coarse fraction contains more zinc carbonate and less zinc silicate compared with undersize particles. In addition, ore coarse fraction is richer in residual forms (nontronite, sphalerite) hardly soluble in sulphuric acid solution. Thermodynamic analysis of probable transformations during leaching is carried out, kinetics of coarse fraction and undersize particles of ore leaching is studied, and Pourbaix diagrams are plotted for analysis of processes occurring at a phase interface during leaching of oxidized zinc ore. Studies for stripping oxidized zinc ore are carried out on large (–20+1 mm) and small (–1+0 mm) fractions. Optimum leaching parameters are established for fine and coarse ore fractions: sulfuric acid concentration and process temperature and duration (C(H2SO4) = 150–160 g/liter, temperature 60°C, leaching time 60 min). Dependences are determined for the degree of zinc extraction into solution on sulphuric acid concentration, temperature, and leaching duration for coarse and fine ore factions.

Pedogenesis in mine tails affects macroporosity, hydrological properties, and pollutant flow

Mining activities take a direct impact on the environment, particularly when this activity is focused on metal-ore exploitation. Abandoned metal mine areas contain different types of residues from ore-processing operations that are typically characterized by high concentrations of heavy metals. One consequence is the generation of acid-mine drainage, caused by the oxidation and hydrolysis of metal sulphides. Mine tail soils have been studied under several points of view, but not on how crack formation affects their properties and functioning, before irreversible hardening. The Cartagena–La Union mining district is one of the more ancient Spanish mining regions. This region is placed at the south-eastern part of Spain, and contains one of the largest lead and zinc ore deposits in South Europe, which was exploited for Au, Ag, Pb, Zn, Fe and Cu from the Phoenician and Carthaginian times. The aim of this research work was to characterize the pedogenesis that occurred in mine tailings of different age and properties, to highlight the physical and hydrological changes that occurred as a consequence of pedogenesis, and their consequences on the environmental pollution risk. Soil profile morphology was studied in the field likewise the surficial pattern of cracks, shear strength, bulk density, and erosion. Laboratory analyses were conducted to characterize physical, chemical, elemental, mineralogical, and hydrological differences between the soil mass in the macro aggregates and in the fissures. Macroporosity was studied through image analysis of thin sections of undisturbed soil samples. X-ray diffraction (XRD) was performed on the clay fraction. Studied soils resulted strongly polluted, especially as for Zn, Pb, Cd, Cl, Mn, and Ni and were classified as different kinds of Spolic Technosol. Crack formation significantly affected shear strength, bulk density, macroporosity, saturated hydraulic conductivity, and element distribution. Gully and tunnel erosion was also driven by crack formation. The mineralogy of the clay fraction revealed that smectites are present, favouring crack opening. Crack formation deeply affected soil features and behaviour, namely hydrological properties and flow of pollutants, which in turn condition environmental health and possible soil stabilization and reclamation strategies.

Fueling the Boom: Coal as the Primary Source of Energy for Processing Zinc in China and Comparison with Europe, ca. 1720-1820

AbstractStemming from an examination of the zinc industry in early modern China, this article centers on a detailed survey of coal, the primary source of energy for processing zinc. On the basis of Qing archival documents, this article investigates the previously unknown spatial relationship of zinc ore deposits, coal mines, and zinc smelters; provides quantitative evidence of coal use by estimating the annual consumption of coal in processing zinc; offers a new perspective on the general use of coal in Qing China; and compares the coal-fuel efficiency problem in early European and Chinese zinc production.

Geology, geochemistry, and geochronology of the Dunde iron–zinc ore deposit in western Tianshan, China

The Dunde iron–zinc deposit (185Mt at 35% Fe), located in the Tianshan orogenic belt, Xinjiang, northwest China, is hosted in late Carboniferous volcanic–volcaniclastic rocks characterized by prograde skarn formation and retrograde alteration, but the ore lacks any clear spatial link with intrusive rocks. Four stages of skarn formation and ore development can be recognized: (1) a prograde skarn stage that formed grossularitic garnet (Gr39–80; Ad15–58) and diposidic pyroxene (Di63–97); (2) a retrograde skarn stage dominated by the formation of magnetite with minor epidote, ferropargasite, apatite, hematite, and trace amounts of titanite and spinel; (3) a sulfide stage dominated by the formation of arsenide (loellingite and arsenopyrite) and sulfide minerals (sphalerite, pyrrhotite, pyrite, chalcopyrite, and minor galena), calcite, and traces of quartz; and (4) a chlorite–calcite stage mainly characterized by the formation of chlorite, calcite, and traces of sericite. Exsolution of droplet-like and patchy chalcopyrite is developed within sphalerite of the sulfide stage, indicating an exsolution temperature of 350–400°C. As such, the crystallization temperature of early stage magnetite may have been >400°C. Abundant fluid inclusions occur in calcite, which include daughter-mineral-bearing H2O, H2O, and pure H2O inclusions. The H2O inclusions have a wide range of homogenization temperatures from 147°C to 367°C with salinities of 2.4–23.4wt.% NaCl equivalent. The daughter-mineral-bearing H2O inclusions have homogenization temperatures from 172°C to 347°C with salinities of 31.9–33.0wt.% NaCl equivalent. Using the chlorite geothermometer, the temperature of chlorite formation is constrained to be between 152°C and 222°C (average=194°C). Sulfur isotope compositions of pyrrhotite, sphalerite, pyrite, and loellingite have a narrow range of δ34S values from 3.8‰ to 8.1‰ (average δ34S=6.8‰), suggesting that the sulfur was magmatic-derived. Zircon LA–ICP-MS U–Pb dating of wall rock dacite yields a weighted mean 206Pb/238U age of 316.0±1.7Ma. Combined with previous dating results of magnetite-mineralized diorite stocks, diorite dikes, and garnet skarn, it can be inferred that the Dunde iron–zinc deposit formed in the late Carboniferous after 316Ma and is genetically related to deep dioritic intrusions. During the late Carboniferous, the tectonic setting of this region changed from subduction–collision to extension, accompanied by mantle-derived magma underplating in deep. After the formation of the iron–zinc ore deposit, the Dunde district was intruded by an early Permian K-feldspar granite that yields a zircon LA–ICP-MS U–Pb age of 295.75±0.71Ma.

Iron and sulfur speciation in some sedimentary-transformation-type of lead–zinc deposits in West Kunlun lead–zinc ore deposit zone, Northwest China

Redox conditions are very important for almost all geological processes including ore deposit formation. However, the direct measurement of redox potential (Eh) values for solid materials is difficult. The chemical speciation of redox sensitive elements is one factor which determines the redox conditions. In this study, four groups of ore samples and their host rocks were collected from four sites along the west Kunlun lead-zinc ore deposit zone in northwest China and the iron- and sulfur- species analyzed using Mossbauer spectroscopy and X-ray absorption near edge fine structure (XANES). The results showed systematical change in redox conditions between the ore rocks and their associated host rocks. All ore samples contained more reducing sulfur species than their corresponding host-rocks indicating significantly enhanced reducing conditions in the ore bodies than their host rocks. Such reducing conditions should be more favorable for the sulfidization of metal during the ore formation. In addition very small concentrations of ferrous iron were found in only some of the small samples. This may indicate the removal of iron during metal sulfide ore deposit formation.

Radioactivity of mining sites of lead, zinc and phosphate ores in Serbia

Natural resources such as ores contain radioactive nuclides at various concentrations. Therefore it is important to investigate the radioactivity in these resources as well as in the soil at the locations of ore deposits. For that reason we conducted preliminary measurements in the soil samples taken from the locations of lead and zinc ore deposits in Bosilegrad and Raška and from the locations of phosphate ore deposits in Bosilegrad to estimate the environmental conditions prior to the ore excavation. The activity concentrations of radionuclides in soil, water and plant samples were determined by gamma spectrometry (HPGe detector, relative efficiency 23%). Results showed the presence of natural radionuclides 226Ra, 232Th, 40K, 235U, 238U as well as the produced radionuclide 137Cs (from the Chernobyl accident). Ambient gamma radiation dose rate in ground level air was also measured. In order to estimate the influence of subsequent mining on the working and living environment, radium equivalent (Raeq), external hazard index (Hex), external gamma absorbed dose rate () and annual effective dose (DE) were determined.

New survey of lead and zinc ore mineralization in Republic of Kosovo

Kosovo lead and zinc ore deposits are located in the Trepca Belt which extends for over 80 km. Several ore deposits occur in that belt, with the most important - Stan Terg (Trepca). Stan Terg deposit originating at the contact between volcanic breccias and carbonate rocks. Two different types of mineralization can be distinguished. The older one has origin related to pneumatolitic processes, when skarns were formed. The more recent one was formed by hydrothermal processes and has the largest economic importance. Over 70 minerals have been recognized in the Trepca deposit. Further mineralogical investigations will allow for the identification of other rare minerals.

Cracking mechanisms during galena mineralization in a sandstone-hosted lead–zinc ore deposit: case study of the Jinding giant sulfide deposit, Yunnan, SW China

There are two types of lead–zinc ore bodies, i.e., sandstone-hosted ores (SHO) and limestone-hosted ores (LHO), in the Jinding giant sulfide deposit, Yunnan, SW China. Structural analysis suggests that thrust faults and dome structures are the major structural elements controlling lead–zinc mineralization. The two types of ore bodies are preserved in two thrust sheets in a three-layered structural profile in the framework of the Jinding dome structure. The SHO forms the cap of the dome and LHO bodies are concentrated beneath the SHO cap in the central part of the dome. Quartz, feldspar and calcite, and sphalerite, pyrite, and galena are the dominant mineral components in the sandstone-hosted lead–zinc ores. Quartz and feldspar occur as detrital clasts and are cemented by diagenetic calcite and epigenetic sulfides. The sulfide paragenetic sequence during SHO mineralization is from early pyrite to galena and late sphalerite. Galena occurs mostly in two types of cracks, i.e., crescent-style grain boundary cracks along quartz–pyrite, or rarely along pyrite–pyrite boundaries, and intragranular radial cracks in early pyrite grains surrounding quartz clasts. The radial cracks are more or less perpendicular to the quartz–pyrite grain boundaries and do not show any overall (whole rock) orientation pattern. Their distribution, morphological characteristics, and geometrical relationships with quartz and pyrite grains suggest the predominant role of grain-scale cracking. Thermal expansion cracking is one of the most important mechanisms for the generation of open spaces during galena mineralization. Cracking due to heating or cooling by infiltrating fluids resulted from upwelling fluid phases through fluid passes connecting the SHO and LHO bodies, provided significant spaces for crystallization of galena. The differences in coefficients of thermal expansion between pyrite and quartz led to a difference in volume changes between quartz grains and pyrite grains surrounding them and contributed to cracking of the pyrite grains when temperature changed. Combined thermal expansion and elastic mismatch due to heating and subsequent cooling resulted in the radial and crescent cracking in the pyrite grains and along the quartz–pyrite grain boundaries.

Geology and Zinc Ore Deposits of Pa-Daeng Area, Maesod District, Thailand

Geology and Zinc Ore Deposits of Pa-Daeng Area, Maesod District, Thailand

Local, Regional, and Global Implications of Elemental Mercury in Metal (Copper, Silver, Gold, and Zinc) Ores: Insights from Lake Superior Sediments

Anthropogenic inventories for copper (229 ± 89 ug/cm 2, N = 30), and mercury (470 ± 307 ng/cm 2, N = 25) in Lake Superior sediments are much greater than inventories in remote lakes (Cu 50 ± 31 ug/cm 2, Hg 64 ± 34 ng/cm 2, N = 16) that receive inputs largely from long-distance atmospheric sources. Whereas the absolute concentration of mercury in Lake Superior sediments is not high (80–110 ng/g), enrichment ratios along coastal margins indicate industrial sources. An example of previously unreported mining-related inputs comes from native copper mining on the Keweenaw Peninsula. Around the peninsula, sediment inventories for mercury, silver, and copper are highly correlated and can be traced back to shoreline tailing piles, smelters, and parent ores. Elemental mercury occurs as a natural amalgam or solid solution substitution in native metal (copper, silver, gold) deposits and associated gangue minerals (e.g., sphalerite, ZnS) at μg/g or higher concentrations. Native copper stamp mills discharged more than 364 million metric tons of “stamp sand” tailings, whereas copper smelters refined five million metric tons of copper, liberating together at least 42 metric tons of mercury. Release of trace mercury from Lake Superior mining deserves regional attention as preliminary estimates resemble EPA Region #9 patterns and could help explain the 4–7 fold sediment inventory discrepancies. We show that the Keweenaw situation is not unique geographically, as mineral-bound trace mercury is commonplace in U.S. and Canadian Greenstone Belts and of worldwide occurrence in precious (gold, silver) and massive base metal (copper, zinc) ore deposits.

Application of spectral time domain induced polarisation method to resolve orebody characterisation

One of the most important issues in searching for metallic ores is to discriminate between different types and textures of mineralisations. One of the methods capable of deriving such information is the spectral induced polarisation (SIP). With advances in the time domain IP receivers it is possible to get SIP data with no more additional costs. Therefore using Cole-Cole impedance model for the subsurface it is possible to calculate the apparent Cole-Cole parameters by a curve matching technique in a least squares sense. In the current study, SIP measurements have been obtained using six chargeability slices of the transient decay curve after a 2 seconds square wave current on time at the Irankuh lead and zinc ore deposit complex. It is shown that the SIP measurements will give additional valuable textural and structural information which can be of great help in determining and delineating ore blocks for a systematic exploration program. It was found that the increase in time constant is associated with the ore zones with continuous and greater grain size of IP sources. The average frequency exponent for the vein type ores was found to be about three times larger than that of the disseminated ore zones. Also from the true chrageabilities obtained from SIP analysis, the location of the vein type ores was delineated with a higher resolution. Finally due to its cost efficiency and faster field operation it is suggested to collect SIP data for exploration targets where the textural information can play a very important role in dividing ore to the blocks with similar characteristics.