Zn Ag Research Articles

Sulfidic and non-sulfidic indium mineralization of the epithermal Au–Cu–Zn–Pb–Ag deposit San Roque (Provincia Rio Negro, SE Argentina) — with special reference to the “indium window” in zinc sulfide

At San Roque in Patagonia's Rio Negro Province, Argentina, an In–Au–Cu–Zn–Pb–Ag mineralization (<0.24wt.% In, <7ppm Au, <0.45wt.% Cu, <14.1wt.% Zn, <0.55wt.% Pb, <60ppm Ag) is bound to lava, and volcaniclastics of Triassic through Jurassic age. The polymetallic sulfidic and non-sulfidic indium mineralization is attributed to the low-sulfidation (LS) to intermediate sulfidation (IS) epithermal type of mineralization. Its vein-type and stockwork mineralization developed at 39.2bars under hydrostatic conditions, corresponding to a depth of 400m below the water level of the paleoaquifer. In the redox-controlled hypogene mineralization, the temperature increased from 130°C up to as much as 250°C at depth, while the pH regime changed from slightly acidic near surface to more alkaline conditions around pH 8 at a depth of approximately 150m. The monophase mineral associations composed of sphalerite, Ag–Bi-enriched and inclusion-free galena (<1.7wt.% Ag, <3.7wt.% Bi), chalcopyrite, pyrite, gold, silver, digenite, various In–Cu- and Pb–Zn–Ag “intermediate products”, wittichenite, roquesite, sakuraiite, dzhalindite, brochantite, antlerite, cerussite, and “manganomelane” in a quartz and muscovite-rich gangue have been subdivided into three different stages: (1) Stockwork mineralization of LS to IS epithermal type (hypogene), (2) quartz vein mineralization (hypogene), and (3) salar mineralization (supergene–hypogene).Salt–mud flats controlled the youngest mineralization with Mn, Li, Ca, Mg, V, Sr, Cu, Ag and In bound to oxides, hydroxides, sulfates and subordinate carbonates. The quartz vein mineralization is made up of oxides, hydroxides prevailing over sulfides and containing W, Fe, Au, As, Pb, In, and Cu. It formed at the passage from the vadose into the phreatic zones under oxidizing to slightly reducing conditions. The level marks the boiling level of the hydrothermal solutions involved in the mineralizing process. The hypogene stockwork mineralization is exclusively made up of sulfides containing Zn, Pb, Cu, In, Ag and Bi in the phreatic zones. It developed under reducing conditions. Indium is present at all levels within the volcanic rocks and has been derived from sphalerite rich in Cd (<1.6wt.% Cd), In (<7.3wt.% In) and Cu (<7.2wt.% Cu) while the Fe contents are moderate in sphalerite (<6.8wt.% Fe). Indium reached economic grade only through the segregation of a Cu–In–S phase in the “indium window” which is defined by a Cd content of sphalerite in the range 0.2–0.6wt.% Cd. This concentration of In is controlled by the crystal morphology and the lattice parameters of the minerals involved. It is described as a two-stage process with interdiffusion processes in an Fe-enriched system (stage I) and zoned replacement in an Fe-poor system enriched in indium (stage II). Cu-bearing sphalerite decomposed into sphalerite poor in trace elements and into Cu–In-bearing sphalerite. Further indium concentration took place, when roquesite and sakuraiite decomposed along with an increase in oxygen pressure under hypogene and supergene conditions into dzhalindite. The physical–chemical conditions of the mineralogy and chemical changes in the system In–Cu–Zn–Cd observed in nature have been approximated based upon the results obtained during laboratory studies in material sciences that were focused on solar energy.

Geological, fluid inclusion and isotopic studies of the Yinshan Cu–Au–Pb–Zn–Ag deposit, South China: Implications for ore genesis and exploration

The Yinshan Cu–Au–Pb–Zn–Ag deposit is located in Dexing, South China. Ore bodies are primarily hosted in low-grade phyllite of the Neoproterozoic Shuangqiaoshan Group along EW- and NNW-striking fault zones. Pb–Zn–Ag mineralization is dictated by Jurassic rhyolitic quartz porphyries (ca. 172Ma), whereas Cu–Au mineralization is associated with Jurassic dacite porphyries (ca. 170Ma). The main ore minerals are pyrite, chalcopyrite, galena, sphalerite, tetrahedrite–tennatite, gold, silver, and silver sulphosalt, and the principal gangue minerals are quartz, sericite, calcite, and chlorite. Two-phase liquid-rich (type I), two-phase vapor-rich (type II), and halite-bearing (type III) fluid inclusions can be observed in the hydrothermal quartz-sulfides veins. Type I inclusions are widespread and have homogenization temperatures of 187–303°C and salinities of 4.2–9.5wt.% NaCl equivalent in the Pb–Zn–Ag mineralization, and homogenization temperatures of 196–362°C and salinities of 3.5–9.9wt.% NaCl equivalent in the Cu–Au mineralization. The pervasive occurrence of type I fluid inclusions with low-moderate temperatures and salinities implies that the mineralizing fluids formed in epithermal environments. The type II and coexisting type III inclusions, from deeper levels below the Cu–Au ore bodies, share similar homogenization temperatures of 317–448°C and contrasting salinities of 0.2–4.2 and 30.9–36.8wt.% NaCl equivalent, respectively, which indicates that boiling processes occurred. The sulfur isotopic compositions of sulfides (δ34S=−1.7‰ to +3.2‰) suggest a homogeneous magmatic sulfur source. The lead isotopes of sulfides (206Pb/204Pb=18.01–18.07; 207Pb/204Pb=15.55–15.57; and 208Pb/204Pb=38.03–38.12) are consistent with those of volcanic–subvolcanic rocks (206Pb/204Pb=18.03–18.10; 207Pb/204Pb=15.56–15.57; and 208Pb/204Pb=38.02–38.21), indicating a magmatic origin for lead in the ore. The oxygen and hydrogen isotope compositions (δ18O=+7.8‰ to +10.5‰, δD=−66‰ to −42‰) of inclusion water in quartz imply that ore-forming fluids were mainly derived from magmatic sources. The local boiling process beneath the epithermal Cu–Au ore-forming system indicates the possibility that porphyry-style ore bodies may exist at even deeper zones.

Footwall mineralization during Late Miocene extension along the West Cycladic Detachment System, Lavrion, Greece

AbstractThe West Cycladic Detachment System (WCDS) has been mapped from the western Cycladic islands to Lavrion (mainland Greece), where several top‐to‐SSW low‐angle normal faults at different structural levels are observed. Near the detachment horizon, hydrothermal fluid flow originating from Miocene intrusions lead to high‐temperature carbonate strata‐bound Pb–Ag–Zn ore deposits. Zircon (U–Th)/He cooling ages from the mineralized footwall are 7.1 ± 0.6 to 7.9 ± 0.6 Ma. Carbon‐ and O‐isotope analyses of the carbonate host indicate high water‐to‐rock ratios during brittle deformation‐induced metasomatism, and that this interaction, unrelated to proximity of the intrusions, plays the dominant role in the mineralization. The Late Miocene geology of Lavrion is strikingly similar to Serifos island on the SE termination of the WCDS, both characterized by strong localization of detachment faulting and the interaction of brittle deformation with the injection of fluids related to granitoid intrusions.

Chukhrovite-(Ca), Ca4.5Al2(SO4)F13·12H2O, a new mineral species from the Val Cavallizza Pb-Zn-(Ag) mine, Cuasso al Monte, Varese province, Italy

Chukhrovite-(Ca), Ca 4.5 Al 2 (SO 4 )F 13 ·12H 2 O, is the Ca-dominant species of the chukhrovite mineral group. It occurs at the Val Cavallizza Pb–Zn–Ag mine, Cuasso al Monte, Varese province, Italy. Chukhrovite-(Ca) is found as low temperature hydrothermal crystallizations covering the surfaces of brittle fractures crosscutting a marcasite and REE-bearing fluorite vein. Associated minerals include marcasite, gypsum, and hydrated Fe oxides. This new calcium aluminofluoride forms sharp octahedra up to 150 μm in diameter. Crystals are translucent to transparent, colourless to white, with a white streak and a vitreous lustre. Chukhrovite-(Ca) is isotropic with n = 1.432(1), and is non-fluorescent either under short-wave (254 nm) or long-wave (366 nm) ultraviolet light. The mineral is brittle with a Mohs hardness of 3.5(5), and without a distinct cleavage or fracture. Its density, calculated from the single-crystal unit-cell parameters and assuming 12 H 2 O molecules per formula unit, is 2.23 g/cm 3 . The empirical formula, based on 3 (Al + S) atoms per formula unit and calculated from an average of five selected point analyses, is: (Ca 4.33 Na 0.11 Fe 0.03 ) ∑4.47 Al 2.10 (S 0.90 O 3.72 ) F 13.10 ·5.98H 2 O, with the water content calculated by difference to 100 %. Chukhrovite-(Ca) is cubic with space group Fd 3; its single-crystal unit-cell parameters are a = 16.749(1) A and V = 4698.6(1) A 3 , for Z = 8. The eight strongest lines in the X-ray powder diffraction pattern are [ d in A ( I / I 0 ) hkl ]: 9.665 (100) 111, 5.921 (31) 022, 5.053 (16) 113, 4.190 (10) 004, 3.226 (15) 333 and 115, 2.556 (10) 533, 2.182 (12) 355 and 137, 1.915 (17) 626. The mineral, which has been approved by the CNMNC under number IMA 2010-081, is named chukhrovite-(Ca), since it corresponds to the Ca-rich equivalent of chukhrovite-(REE) (REE = Ce, Nd, Y), in which REE are replaced by Ca.

Silver-base metal epithermal vein and listwanite hosted deposit Crnac, Rogozna Mts., Kosovo, part II: A link between magmatic rocks and epithermal mineralization

Crnac is an intermediate sulfidation Pb–Zn–Ag epithermal deposit located within the Vardar suture zone of the Central Balkan Peninsula. The epithermal Pb–Zn–Ag mineralization consists of (i) a series of steeply-dipping veins hosted within the Jurassic amphibolites, and (ii) overlying hydrothermal-explosive breccia with angular (level IV) or rounded fragments of listwanite (surface) cemented by epithermal mineralization. The mineralization is related to the Oligocene quartz latite dykes that crosscut the Crnac antiform. Quartz latite rocks predominantly display a shoshonitic character. The obtained 40Ar/39Ar age of fresh quartz latite is 28.9±0.3Ma. Fine-grained sericite from altered quartz latite is dated at 28.6±0.5Ma. Early, alteration related fluid inclusions within quartz latite show coexistence of high-density brine and a low-density vapor-saturated phase that homogenized at 280–405°C. Phase separation occurs at a paleodepth of 0.6 to 0.9km.Epithermal mineralization developed in three stages: (i) early pyrite–arsenopyrite–pyrrhotite–quartz–kaolinite; (ii) main sphalerite–galena–tetrahedrite–chalcopyrite and (iii) late carbonate–pyrite–arsenopyrite assemblage. The onset of mineral deposition within epithermal veins was initiated by boiling of Na–Cl±K±Ca±Mg fluid at a paleodepth of 0.6 to 0.9km. Coexisting vapor and liquid-rich inclusions display salinities and trapping temperatures of 4wt.% NaCl equiv., 280–370°C and 2–27wt.% NaCl equiv., 230–375°C, respectively. Boiling continued throughout the deposition of the sphalerite-galena-tetrahedrite-chalcopyrite assemblage. Late stage carbonate was deposited from diluted, non-boiling, low-temperature Na–Ca–Mg–Cl±CO2 fluid (0.2 to 4.8wt.% NaCl equiv., 115–280°C).About 100–150m higher in the system, precipitation of listwanite breccia cement began as a result of boiling Na–Cl±Ca±Mg±K fluid of medium salinities (2.6 to 12.1wt.% NaCl equiv.) at temperatures of 245–370°C. Boiling and dilution of fluids continue throughout the precipitation of the main sphalerite-galena-tetrahedrite and late, mainly carbonate assemblage. Surface listwanite breccia contain quartz phenocrysts deposited from a homogeneous fluid with a medium salinity (8–10wt.% NaCl equiv.) and high temperatures (Th=295–315°C), whereas the early and main stage of a surface listwanite breccia cement precipitated from a boiling fluid of decreasing salinity and temperature. Aqueous ±CO2, high salinity (16 to 18wt.% NaCl equiv.), low temperature (120°C), homogeneously trapped fluid that precipitated late stage carbonates, is most likely a remnant of boiled off fluid. The epithermal assemblage of the surface listwanites precipitated at a paleodepth of 0.4 to 0.6km.The δ13C values of the late stage ankerite range from −4.2 to 4.1‰, whereas δ18O range from 9.6 to 17.5‰. The calculated δ18O of fluid that precipitated carbonates within epithermal veins, and listwanite breccia cement range from 6.3 to 11.3‰, indicating a contribution of magmatic water.Deposition of all mineralization types was initiated by neutralization of primary acidic magmatic fluid by water-rock reactions that caused widespread propylitization and sericitization. Extensive and long-lasting boiling combined with dilution by meteoric water increased the pH towards the final stage of hydrothermal activity.

Theoretical investigation on structural and thermodynamic properties of the intermetallic compound in Mg–Zn–Ag alloy under high pressure and high temperature

A theoretical investigation on structural and thermodynamic properties of intermetallic compounds MgAg, Mg4Zn8 and Mg4Zn4Ag8 in Mg–Zn–Ag alloy at high pressure and high temperature are performed by employing the first-principles method based on the density functional theory. The calculated values are generally speaking in good agreement with experiments and similar theoretical calculations. Theoretical calculated results indicate that intermetallic compounds MgAg, Mg4Zn8 and Mg4Zn4Ag8 are elastically stable at zero temperature and pressure. Mg4Zn8 and Mg4Zn4Ag8 are the ductility phases, and MgAg is the brittleness phase. In addition, the calculations of elastic constants and Young modulus show that the plasticity of Mg4Zn4Ag8 is the best in the three intermetallic compounds, and MgAg is the worst. Based on the quasi-harmonic Debye model, the vibrational internal energy, vibrational Helmholtz free energy, vibrational entropy, heat capacity, thermal expansion coefficient, Grüneisen parameter and Debye temperature of the intermetallic compounds in Mg–Zn–Ag alloy at high pressure and high temperature are discussed.

Major types and time–space distribution of Mesozoic ore deposits in South China and their geodynamic settings

The ore deposits of the Mesozoic age in South China can be divided into three groups, each with different metal associations and spatial distributions and each related to major magmatic events. The first event occurred in the Late Triassic (230–210 Ma), the second in the Mid–Late Jurassic (170–150 Ma), and the third in the Early–Mid Cretaceous (120–80 Ma). The Late Triassic magmatic event and associated mineralization is characterized by peraluminous granite-related W–Sn–Nb–Ta mineral deposits. The Triassic ore deposits are considerably disturbed or overprinted by the later Jurassic and Cretaceous tectono-thermal episodes. The Mid–Late Jurassic magmatic and mineralization events consist of 170–160 Ma porphyry–skarn Cu and Pb–Zn–Ag vein deposits associated with I-type granites and 160–150 Ma metaluminous granite-related polymetallic W–Sn deposits. The Late Jurassic metaluminous granite-related W–Sn deposits occur in a NE-trending cluster in the interior of South China, such as in the Nanling area. In the Early–Mid Cretaceous, from about 120 to 80 Ma, but peaking at 100–90 Ma, subvolcanic-related Fe deposits developed and I-type calc-alkaline granitic intrusions formed porphyry Cu–Mo and porphyry-epithermal Cu–Au–Ag mineral systems, whereas S-type peraluminous and/or metaluminous granitic intrusions formed polymetallic Sn deposits. These Cretaceous mineral deposits cluster in distinct areas and are controlled by pull-apart basins along the South China continental margin. Based on mineral assemblage, age, and space–time distribution of these mineral systems, integrated with regional geological data and field observations, we suggest that the three magmatic–mineralization episodes are the result of distinct geodynamic regimes. The Triassic peraluminous granites and associated W–Sn–Nb–Ta mineralization formed during post-collisional processes involving the South China Block, the North China Craton, and the Indo-China Block, mostly along the Dabie-Sulu and Songma sutures. Jurassic events were initially related to the shallow oblique subduction of the Izanagi plate beneath the Eurasian continent at about 175 Ma, but I-type granitoids with porphyry Cu and vein-type Pb–Zn–Ag deposits only began to form as a result of the breakup of the subducted plate at 170–160 Ma, along the NNE-trending Qinzhou-Hangzhou belt (also referred to as Qin-Hang or Shi-Hang belt), which is the Neoproterozoic suture that amalgamates the Yangtze Craton and Cathaysia Block. A large subduction slab window is assumed to have formed in the Nanling and adjacent areas in the interior of South China, triggering the uprise of asthenospheric mantle into the upper crust and leading to the emplacement of metaluminous granitic magma and associated polymetallic W–Sn mineralization. A relatively tectonically quiet period followed between 150 and 135 Ma in South China. From 135 Ma onward, the angle of convergence of the Izanagi plate changed from oblique to parallel to the coastline, resulting in continental extensional tectonics and reactivation of regional-scale NE-trending faults, such as the Tan-Lu fault. This widespread extension also promoted the development of NE-trending pull-apart basins and metamorphic core complexes, accompanied by volcanism and the formation of epithermal Cu–Au deposits, granite-related polymetallic Sn–(W) deposits and hydrothermal U deposits between 120 and 80 Ma (with a peak activity at 100–90 Ma).

Efficiency of extraction of polycyclic aromatic hydrocarbons from the Paleoproterozoic Here’s Your Chance Pb/Zn/Ag ore deposit and implications for a study of Bitumen II

Demineralisation of a sedimentary rock with HF liberates a fraction of extractable organic matter (OM) that is not accessible with standard extraction techniques, which is known as Bitumen II. This fraction displays lower maturity parameters than the free extractable OM (Bitumen I). Studies of successive conventional extraction have found that the later steps show a decrease in maturity similar to that observed for Bitumen II. We aimed to investigate whether or not Bitumen II is simply the result of residual Bitumen I left over from the initial extraction.A series of successive Soxhlet extraction steps was performed on a highly mineralised sample from the Paleoproterozoic Here’s Your Chance (HYC) Pb–Zn–Ag deposit in the Northern Territory of Australia. The study showed that the extraction efficiency for polycyclic aromatic hydrocarbons (PAHs) decreased with increasing molecular weight. Maturity parameters based on methyl phenanthrenes generally decreased with successive extraction steps. This is because the thermodynamically more stable β isomers were preferentially extracted over the α isomers, so later extraction steps contained a greater proportion of α isomers. Bitumen II was prepared from a previously-studied sample from the same sample pit. It showed a decrease in maturity parameters relative to Bitumen I, but the distribution of PAHs did not match those of the later Bitumen I extraction steps. We conclude that Bitumen II did not result from incomplete extraction of Bitumen I. As Bitumen II is preserved within the kerogen–mineral matrix, it has potential for tracing the migration and maturation history of ancient or thermally altered systems.

Fabrication and evaluation of low-cost agarose–zinc nanoporous composite matrix: Influence of adsorbent density and size distribution on the performance of expanded beds

Expanded bed adsorption (EBA), a promising and practical separation technique for adsorption of nanobioproduct/bioproduct, has been widely studied in the past two decades. The development of adsorbent with the special design for expanded bed process is a challenging course. To reduce the costs of adsorbent preparation, fine zinc powder was used as the inexpensive densifier. A series of matrices named Ag–Zn were prepared by water-in-oil emulsification method. The structure and morphology of the prepared matrix were studied by the optical microscope (OM) and scanning electron microscopy (SEM). The physical properties as a function of zinc powder ratio to agarose slurry were measured. The prepared matrices had regular spherical shape, and followed logarithmic normal size distribution with the range of 75–330μm, mean diameter of 140.54–191.11μm, wet density of 1.33–2.01g/ml, water content of 0.45–0.75, porosity of 0.86–0.97 and pore size of about 40–90nm. The bed expansion factor at the range of 2–3 was examined. The obtained results indicated that the expansion factor was decreased with increasing of matrix density. In addition, it was found that matrices with large particle size were suitable for high operation flow rate. The hydrodynamic properties were determined in expanded bed by the residence time distribution method (RTD). The effects of flow velocity, expansion factor and density of matrix on the hydrodynamic properties were also investigated. Moreover, the influence of particle size distribution on the performance of expanded bed has been studied. Therefore, three different particle size fractions (65–140, 215–280 and 65–280μm) were assessed. The results indicated that dispersion in liquid–solid expanded beds increased with increasing flow rate and expansion factor; and matrix with a wide particle size distribution leaded to a reduced axial dispersion compared to matrices with a narrow size distribution. The axial dispersion coefficient also enhanced with the increasing of matrix density. It was found that flow rate was the most essential factor to effect on the hydrodynamic characteristics in the bed. For all the prepared matrices, the values of axial mixing coefficients (Daxl) were smaller than 1.0×10−5m2/s when flow velocities in expanded bed were less than 700cm/h. All the results indicate that the prepared matrix show good expansion and stability in expanded bed; and it is suitable for expanded bed processes as an economical adsorbent.

Study on melt properties, microstructure, tensile properties of low Ag content Sn–Ag–Zn Lead-free solders

Sn–Ag solders have been regarded as the most promising solders to replace Sn–Pb solders in the future, but the reliability and cost issues limit its use. Therefore a low-Ag content Sn–Ag–Cu solder, SAC105 was researched, which still has some problems. Sn–Ag–Zn solders are obviously superior in many aspects in comparison to Sn–Ag–Cu solders, but the low-Ag Sn–Ag–Zn solders were rarely studied. In this paper, properties of Sn–xAg–yZn (x=1, 1.5, 2, 3; y=1, 1.5, 2, 2.5, 3, 4) solders, including melt properties, microstructure, and tensile properties were investigated. It was found that reduction of Ag content in Sn–Ag–Zn solders leads to the same problems as in Sn–Ag–Cu solders in melt properties and tensile properties. Although Sn–xAg–1Zn solders have higher strength, the elongation is lower. Results show that melt properties and tensile properties can be improved by the optimization of Zn content, but excessive Zn additon could lead to worse properties as well. Sn–2Ag–2.5Zn and Sn–1.5Ag–2Zn solders were found to have optimized properties. In addition, relations between melt properties and microstructure, as well as microstructure and tensile properties, were discussed.

Multiple Mesozoic mineralization events in South China—an introduction to the thematic issue

Mesozoic mineral deposits in South China include world-class deposits of W, Sn and Sb and those that provide the major sources of Ta, Cu, Hg, As, Tl, Pb, Zn, Au and Ag for the entire country. These deposits can be classified into polymetallic hydrothermal systems closely related to felsic intrusive rocks (Sn–W –Mo granites, Cu porphyries, polymetallic and Fe skarns, and polymetallic vein deposits) and low-temperature hydrothermal systems with no direct connection to igneous activities (MVT deposits, epithermal Au and Sb deposits). Recent studies have shown that they formed in the Triassic (Indosinian), Jurassic–Cretaceous (Early Yanshanian), and Cretaceous (Late Yanshanian) stages. Indosinian deposits include major MVT (Pb–Zn–Ag) deposits and granite-related W–Sn deposits. Early Yanshanian deposits are low-temperature Sb–Au and high-temperature W–Sn and Cu porphyry types. Many Late Yanshanian deposits are low-temperature Au–As–Sb–Hg and U deposits, and also include high-temperature W–Sn polymetallic deposits. The formation of these deposits is linked with a specific tectonothermal evolution and igneous activities. This special issue brings together some of the latest information in eight papers that deal with the origins and tectonic environments of mineral deposits formed in these stages. We anticipate that this issue will stimulate more interests in these ore deposits in South China.

Effect of Ga on the Oxidation Properties of Sn–8.5Zn–0.5Ag–0.1Al–xGa Solders

The oxidation properties of Sn–8.5Zn–0.5Ag–0.1Al–xGa lead-free solders in the liquid state (250 °C) under O2 atmosphere were investigated using a thermal gravimetric analyzer. The Ga content of the investigated solders was 0.05–2 wt%. The results indicate that Ga enhances the oxidation resistance of Sn–Zn–Ag–Al solder. Cross-sections of the solder surfaces were examined using focus ion beam milling. The thickness of the oxidation layer, which was about 30–100 nm, increased with increasing Ga content. The oxidation layer was found to be nonuniform at low Ga content. The oxide layers on the surface of solders were investigated using Auger electron spectroscopy and thin-film XRD. The results showed that the oxide layer formed was ZnO. Al and Ga tended to segregate on the surface of the solder.

Fluid evolution of the Jiawula Ag–Pb–Zn deposit, Inner Mongolia: mineralogical, fluid inclusion, and stable isotopic evidence

The Jiawula Ag–Pb–Zn deposit lies in the renowned Ag–polymetallic metallogenic province of northern China. The origin of this structurally controlled ore body is linked to fluid migration and mineralization along cogenetic fault systems. Sulphur isotopic compositions suggest that the ore-forming aqueous solutions were derived mainly from deep magmatic fluids. Hydrogen and oxygen isotopic compositions indicate that these fluids were magmatic during early stages of ore formation and meteoric during late-stage mineralization. Lead isotopic compositions indicate that this metal was derived mainly from a mantle source, and to a lesser extent from a crustal source. Collectively, the isotopic data indicate that formation of the Jiawula Ag–Pb–Zn deposit was ultimately a reflection of late Yanshanian (140–120 Ma) volcanic–subvolcanic hydrothermal activity. The addition of meteoric water to these magmatic hydrothermal fluids created favourable conditions for mineralization. During ore formation, metallogenesis took place in a relatively open, non-equilibrium system under conditions of low δ34S∑S and an intermediate oxidation state. Microthermometric study of fluid inclusions indicates homogenization temperatures of 180–260°C. Salinities, densities, pressure, and depth of ore-forming fluids ranged from 0.18 to 12.62 wt.% NaCl eqv., 0.637 to 0.976 g/cm3, 3.44 to 162.05 bar, and 0.5 to 1.5 km, respectively. Laser Raman studies of single-phase fluid inclusions show that the ore-forming fluids belong to the H2O–NaCl system. Analysis of bulk chemical compositions of fluid inclusions indicates that the ore-forming fluid can be classified as the Na+–Ca2+––Cl− fluid type. All obtained geochemical data demonstrate that the ore-forming fluids of the Jiawula Ag–Pb–Zn deposit are medium- to low-temperature, medium- to low-pressure, medium- to low-salinity, and low-density fluids. Based on their compositions, they can be classified into two end-members: magmatic hydrothermal fluid and meteoric water. The key factors allowing for metal transport and precipitation during ore formation include the sourcing of magmatic fluids with high contents of metallogenic elements and the mixing of these hydrothermal fluids with meteoric waters resulting in the formation of a large Ag–Pb–Zn deposit. In terms of genetic type, the Jiawula deposit can be regarded as a volcanic–subvolcanic hydrothermal vein Pb–Zn–Ag ore deposit.

Oligocene shoshonitic rocks of the Rogozna Mts. (Central Balkan Peninsula): Evidence of petrogenetic links to the formation of Pb–Zn–Ag ore deposits

This study focuses on age and evolution of the Oligocene quartz latite of the Rogozna Mts. (Central Balkan Peninsula), in order to better understand the link between magmatism and formation of Pb–Zn±Ag mineralization. New 40Ar/39Ar biotite and amphibole plateau ages suggest that the Rogozna Mts. quartz latite originated through a continuous volcanic episode from 27.3±0.1 to 29.5±0.1Ma which was immediately followed by a hydrothermal phase. The quartz latites are hypocrystalline porphyritic with phenocrysts and microphenocrysts (~60vol.%) of plagioclase (An37–49), biotite Mg# [100×Mg/(Mg+Fetot)]<50, calcic amphibole, quartz, sanidine clinopyroxene and phlogopite (Mg#=79 to 84). The rocks display numerous disequilibrium textures, such as: sieved plagioclase phenocrysts, dissolution effects on quartz, phlogopitized biotite and amphibole crystals, and phlogopite microphenocrysts showing effects of incomplete growth (or dissolution?) and biotitization. The Rogozna Mts. quartz latites are shoshonitic in character with Na2O/K2O<1, high LILE/HFSE ratios, strong depletions at Nb and Ti and K, Pb and U peaks on primitive mantle-normalized diagrams. They are similar to other potassic/ultrapotassic rocks in this region, in particular to those of Veliki Majdan and Rudnik (West Serbia), which are also related to Pb–Zn deposits. The evolution of the Rogozna Mts. quartz latite is modeled using a trace element binary mixing model adopting a lamproite magma and a dacite-like calc-alkaline melt as end-members. The model implies that a fractionating magma chamber (~4.5–9.5km) undergoes cooling in the range of >850°C–~720°C and injection of lamproite-like melts. The injection causes an increase of temperature and a decrease of viscosity of the resulting hybrid magma, facilitating its upwelling and triggering pyroclastic eruptions. The addition of new volatiles by lamproitic melts most probably established the conditions for a hydrothermal phase above the magma chamber that was previously degassed explosively. This implies that magma mixing processes can be of great importance for the formation of Pb–Zn deposits. Similar processes are likely to have occurred in other areas with economically significant Pb–Zn–Ag±other metal mineralization in the region of the Central Balkan Peninsula (Veliki Majdan, Rudnik, Golija, Kopaonik, Avala, etc.).

Weathering processes in waste materials from a mining area in a semiarid zone

Chemical and mineralogical characterization of waste materials present in an abandoned Pb, Zn–Ag mining site (SE, Spain) was carried out. In unaltered rocks, the mineralogy is characterized by plagioclase, pyroxene, magnetite, ilmenite, amphibole, biotite and quartz. Trace-element contents of these samples represent unaltered values. In mine-waste materials, pH ranged from acidic to slightly acidic and trace-element content was generally high, especially for Pb and Zn, although there were also substantial As concentrations. X-ray diffraction results suggested that these samples have a complex mineralogy, including alteration products. Surficial materials in the study area were affected by weathering processes, generating supergene assemblages, including Fe and Mn oxides and hydroxides, carbonates, hydrated sulfates and jarosite. Knowledge of the geochemical processes that took place in the past and which are still taking place provide an important tool for assessing associated environmental problems in this area.

Diffusion of Cu and interfacial reactions during reflow of Sn–8.5Zn–0.5Ag–0.01Al–0.1Ga alloy on Ni/Cu substrate

Abstract

Age and tectonic setting of the Bavanat Cu–Zn–Ag Besshi-type volcanogenic massive sulfide deposit, southern Iran

The Bavanat Cu–Zn–Ag Besshi-type volcanogenic massive sulfide (VMS) deposit occurs within the Surian volcano-sedimentary complex in the Sanandaj–Sirjan zone (SSZ) of southern Iran. The Surian complex is comprised of pelite, sandstone, calcareous shale, basalt, gabbro sills, and thin-bedded limestone. Mineralization occurs as stratiform sheet-like and tabular orebodies hosted mainly by greenschist metamorphosed feldspathic and quartz feldspathic sandstone, basalt, and pelites. The basalts of the Surian complex show predominantly tholeiitic to transitional affinities, with a few samples that are alkalic in composition. Primitive mantle-normalized trace and rare earth element (REE) patterns of the Surian basalts display depletions in light REE, negative anomalies of Nb, Ta, and Ti, and positive anomalies of P. Positive P anomalies are indicative of minor crustal contamination. Furthermore, Th enrichments in the mid-ocean ridge basalt-normalized patterns of the Surian basalts are characteristic of rifted arc basalts emplaced in continental margin subduction zones. The high MgO content (>6 wt.%) of most Surian basalts and low TiO2 content of two samples (0.53 and 0.62 wt.%) are characteristic of boninites. The aforementioned features of the basalts indicate arc tholeiites emplaced in intra-arc rift environments and continental margin subduction zones. U–Pb dating by laser ablation- inductively coupled plasma mass spectrometry of detrital zircons extracted from the host feldspathic and quartz feldspathic sandstone yields various ages that are predominantly Permian and Triassic; however, the youngest zircons give a mean Early Jurassic concordant U–Pb age of 191 ± 12 Ma. This age, together with geological and petrochemical data, indicate that VMS mineralization formed in the Early Jurassic in pull-apart basins within the SSZ. These basins and the VMS mineralization may be temporally related to an intra-arc volcano–plutonic event associated with Neo-Tethyan oblique subduction.

Electronic structure and water splitting under visible-light irradiation of Zn and Ag co-doped In(OH)ySz photocatalysts

Zinc and silver co-doped In(OH)ySz with nanocubic blocks morphology were prepared by a one-step hydrothermal method and their photocatalytic activities were investigated. The as-synthesized products were characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma (ICP) and UV–visible spectroscopy. The electron microscope observations revealed that the particle sizes of Zn-doped In(OH)ySz crystals were smaller than that of the non-doped In(OH)ySz, which accords with BET results. While Zn–Ag co-doped In(OH)ySz showed the nanocubic blocks with different particle sizes. The UV–vis spectra indicate that the single Zn ions doping leads to the absorbance band shifts toward lower wavelength upon increasing the Zn doping. Consequently, the band gap of In(OH)ySz also increases gradually with increasing the Zn doping. In contrast, an obvious red-shift is observed for Zn–Ag co-doped In(OH)ySz solid solution, which mainly attributed to the transition from Ag 4d+S 3p orbitals to Zn 4s+In 5s orbitals. The sample doped with 4mol% Ag and Zn was found to have the highest activity, which is 20 times that of the In(OH)ySz.

Evaluate of braze joint strength and microstructure characterize of titanium-CP with Ag-based filler alloy

This research investigates the influences of brazing parameters (temperature and time) on microstructures and the mechanical properties of commercially pure (CP) titanium sheet when it is brazed with CBS34 (Ag–20Cu–22Zn–24Cd) braze filler foil. Brazing was performed in a conventional atmosphere control furnace. The brazing temperatures and holding times employed in this study were 800–870°C and 10–20min, respectively. The qualities of the brazed joints were evaluated by ultrasonic test and the microstructure and phase constitution of the bonded joints were analyzed by means of metallography, scanning electron microscope (SEM) and X-ray diffraction (XRD). The mechanical properties of brazed joints were evaluated by microhardness and shear tests. The diffusion between Ti, Ag, Cu, Zn and Cd from substrate and braze alloy, developed a strong reaction between each other. A number of intermetallic phases, such as TiCu and Ti2Cu in the Ag–Zn solid solution matrix have been identified especially at 870°C – 20min. Both the brazing temperature and the holding time are critical factors for controlling the microstructure and hence the mechanical properties of the brazed joints. The optimum brazing parameters was achieved at 870°C – 20min. Based on the shear test result, all cracks propagate along the brittle intermetallic compounds like Ti2Cu in the reaction layer which typically are composed of quasi-cleavage (Ag–Zn matrix) and brittle appearance.

Study of I‐V characteristics of ZnO film on Si substrate with Ag buffer layer by C‐AFM

PurposeThe purpose of this paper is to demonstrate the I‐V characteristics of ZnO film on Si substrates with Ag buffer layer by conductive atomic force (C‐AFM).Design/methodology/approachAn Ag buffer layer and Zn film was first deposited on silicon substrate by RF‐sputtering deposition method from high pure Ag and Zn target, respectively. Then, the deposited film was sintered in air at 500°C for 1 h.FindingsThe structures and morphologies of the prepared films were characterized by X‐ray diffraction (XRD), energy dispersive spectrum (EDS), atomic force microscopy (AFM), and C‐AFM. The results show that the prepared ZnO films with Ag buffer layer have a good crystallinity and surface morphology. Interestingly, the I‐V curve of ZnO film exhibited typical characteristics of semi‐conductive oxide under the conductive Ag buffer layer.Originality/valueThe paper demonstrates, by C‐AFM, that the ZnO/Ag‐buffer/Si exhibits excellent crystal structure, morphology and typical I‐V characteristics.