Sn Deposits Research Articles

The imprint of hydrothermal fluids on trace-element contents in white mica and tourmaline from the Panasqueira W\u2013Sn\u2013Cu deposit, Portugal

White mica and tourmaline are the dominant hydrothermal alteration minerals at the world-class Panasqueira W–Sn–Cu deposit in Portugal. Thus, understanding the controls on their chemical composition helps to constrain ore formation processes at this deposit and determine their usefulness as pathfinder minerals for mineralization in general. We combine whole-rock geochemistry of altered and unaltered metasedimentary host rocks with in situ LA-ICP-MS measurements of tourmaline and white mica from the alteration halo. Principal component analysis (PCA) is used to better identify geochemical patterns and trends of hydrothermal alteration in the datasets. The hydrothermally altered metasediments are enriched in As, Sn, Cs, Li, W, F, Cu, Rb, Zn, Tl, and Pb relative to unaltered samples. In situ mineral analyses show that most of these elements preferentially partition into white mica over tourmaline (Li, Rb, Cs, Tl, W, and Sn), whereas Zn is enriched in tourmaline. White mica has distinct compositions in different settings within the deposit (greisen, vein selvages, wall rock alteration zone, late fault zone), indicating a compositional evolution with time. In contrast, tourmaline from different settings overlaps in composition, which is ascribed to a stronger dependence on host rock composition and also to the effects of chemical zoning and microinclusions affecting the LA-ICP-MS analyses. Hence, in this deposit, white mica is the better recorder of the fluid composition. The calculated trace-element contents of the Panasqueira mineralizing fluid based on the mica data and estimates of mica-fluid partition coefficients are in good agreement with previous fluid-inclusion analyses. A compilation of mica and tourmaline trace-element compositions from Panasqueira and other W–Sn deposits shows that white mica has good potential as a pathfinder mineral, with characteristically high Li, Cs, Rb, Sn, and W contents. The trace-element contents of hydrothermal tourmaline are more variable. Nevertheless, the compiled data suggest that high Sn and Li contents are distinctive for tourmaline from W–Sn deposits.

Composition of Garnet from the Xianghualing Skarn Sn Deposit, South China: Its Petrogenetic Significance and Exploration Potential

The Xianghualing skarn Sn deposit in the southwestern part of the southern Hunan Metallogenic Belt is a large Sn deposit in the Nanling area. In this paper, the garnet has been analyzed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to obtain the concentrations of the major and trace elements. The results reveal that the garnets from the Xianghualing deposit mainly belong to andradite-grossular (grandite) solid solution and are typically richer in Al than in Fe. They show enrichment in heavy rare earth elements (HREEs) and notably lower light rare earth elements (LREEs), and commonly negative Eu anomalies, indicative of a relatively reduced formation environment. The garnets have high Sn concentrations between 2313 ppm and 5766 ppm. It is also evident that there is a positive correlation between Sn and Fe, suggesting that Sn4+ substitutes into the garnets through substituting for Fe3+ in the octahedral position. Combined with previous studies, it can be recognized that the Sn concentrations of garnet in skarn Sn deposits are generally high, whereas the W concentrations are relatively low. This is just the opposite in garnets from skarn W deposits that typically have high W, but low Sn concentrations. In polymetallic skarn deposits with both economic Sn and W, the concentrations of both metals in garnets are relatively high, although varying greatly. Therefore, the Sn and W concentrations in garnets can be used to evaluate a skarn deposit’s potential to produce Sn and (or) W mineralization, which is helpful in exploration.

Porphyry mineralization in the Tethyan orogen

The Tethyan metallogenic domain (TMD), as one of the three major domains in the world, extends over 10000 km from east to west, and has developed several world-class metallogenic belts, such as the Gangdese porphyry Cu belt, the Sanjiang metallogenic belt, the Iran porphyry Cu belt, the Pakistan porphyry Cu belt, the southeastern European epithermal gold deposit belt, and the Southeast Asian Sn belt. The formation and evolution of the TMD is mainly controlled by the multi-stage subduction of Tethys oceanic slabs, the opening and closing of several small ocean basins, and continent-continent collision. The Tethys oceans include the Proto-Tethys (Cambrian-Silurian), Paleo-Tethys (Carbonaceous-Triassic) and Neo-Tethys (Jurassic to Cretaceous), which in turn are formed by rifting from the Gondwana land at different times in different micro-continents. With a series of geological processes such as oceanic opening and closing, continental collision and post-collisional reworking with intraplate deformation, various types of ore deposits are developed in the TMD, including porphyry deposits, epithermal deposits, VMS deposits, chromite deposits, Sn deposits and orogenic gold deposits. The metallogenic processes of the TMD can be categorized into three stages. (1) Oceanic subduction: With the subduction of the oceanic slab and dehydration of basalt and sediments, the asthenospheric mantle was metasomatized with preliminary enrichment in metals under oxidized condition. (2) Continental subduction: Continental collision induced partial melting of the mantle wedge enriched the metals and water in mafic melts, which ascended from subarc depths to the lower crust, locally to the shallow crust for hydrothermal mineralization. (3) Post-collisional reworking: Partial melting of the mafic intrusives in the lower crust produced felsic melts under oxidized and water-rich conditions, which underwent crystal fractionation and transferred water and metals into hydrothermal fluids for mineralization. The large-scale porphyry mineralization in the TMD mainly occurs in the Miocene, which is an important scientific issue worthy of further study in the future. How is the metal enriched in the processes of gradual maturity of the crust, and how does large-scale mineralization occur in a collisional orogen where there is no subduction and dehydration of oceanic slabs anymore to supply S and Cl? These are still important questions in the study of porphyry mineralization in the Tethyan orogen. The application of hyperspectral and mineralogical studies of alteration assemblages is beneficial for prospecting and exploration in the TMD.

Multistep electrophoretic deposition of TiO2 film and its surface modification for dye sensitized solar cells

Abstract TiO2 is a wide bandgap semiconductor commonly used as a photoanode material in dye sensitized solar cells (DSSCs). However, low absorption of TiO2 in visible range of solar spectrum limits its performance in DSSCs. A multistep electrophoretic deposition (EPD) process was used to improve the morphology of the mesoporous films and high quality TiO2 films were fabricated. Meanwhile, the optical absorbance was enhanced by a convenient and simple surface modification method using tin (Sn). The prepared films were subjected to morphological, optical, elemental, and phase analyses. It was observed that multistep EPD produced high quality films at various electric fields. Moreover, the surface modification was achieved using sonochemical deposition of Sn+ on the film which enhanced its photo-absorption. The current density (J) versus voltage (V) characteristics of Sn/TiO2 film deposited at 20 V based DSSC showed approximately twofold increase in the efficiency of the solar cells. Improved open-circuit voltage (Voc), short-circuit current density (Jsc) and efficiency (η) of the DSSCs as well as significantly high fill factor indicated that the surface modified EPD film is a potential candidate as a photoanode film in DSSCs.

Late Mesozoic high-heat-producing (HHP) and high-temperature geothermal reservoir granitoids: The most significant geothermal mechanism in South China

Differences in the geothermal regime of continental intraplate regions depend mainly on the amount and distribution of radioactive heat production in crustal rocks. Granitoids are the predominant sources of radioactive heat production and have abundant radioactive heat-producing elements, such as uranium, thorium and potassium. The Mesozoic geology of the South China Block (SCB) is characterized by long-term continental reconstruction, widespread granitoids and super-large ore deposits such as U, W, Mo and Sn deposits and is a typical “hot” continent and so-called Mesozoic large granitic province. Unfortunately, so far, research on the geotherm in the SCB is largely concentrated in geophysics and hydrology, with rare studies on the correlation between the geotherm and granitoids. The peak radioactive heat production rates (RHPRs) are consistent with the Mesozoic magmatic pulse. Notably, the varieties of radioactive heat production from the granitoids are not attributed to the differences in the basement rocks. In contrast to previous studies, this study found that not only A-type granitoids but also I-type and S-type granitoids are high-heat-producing (HHP) granitoids. The RHPRs, heat reservoirs and various batholith sizes in the SCB indicate that the large batholiths generally show high RHPRs and heat reservoirs. The distribution of hot springs is closely linked to the radioactive heat production and size of the intrusions. Additionally, we exclude another possibility of an efficient magma chamber with abundant remnant heat beneath the SCB. On the basis of the calculation and analysis of the amount of granitic radioactive heat production, we suggest that the Mesozoic HHP granitoids and high-temperature geothermal reservoir granitoids are the most significant heat source of the crustal geotherm in the SCB.

Combined Zircon, Molybdenite, and Cassiterite Geochronology and Cassiterite Geochemistry of the Kuntabin Tin-Tungsten Deposit in Myanmar

AbstractThe Kuntabin Sn-W deposit, located in southern Myanmar, is characterized by abundant greisen-type and quartz vein-type cassiterite and wolframite mineralization. We have conducted multiple geochronological methods and isotope and trace element analyses to reveal the age and evolution of the Kuntabin magmatichydrothermal system.Zircon U-Pb dating of the two-mica granite yielded a weighted mean 206Pb/238U age of 90.1 ± 0.7 Ma. Cassiterite U-Pb dating provided a lower intercept age of 88.1 ± 1.9 Ma in the Tera-Wasserburg U-Pb concordia diagram. Molybdenite Re-Os dating returned a weighted mean model age of 87.7 ± 0.5 Ma and an isochron age of 88.7 ± 2.7 Ma. These ages indicate a genetic relationship between granite and Sn-W mineralization in the Kuntabin deposit and record the earliest magmatism and Sn-W mineralization in the Sibumasu and Tengchong terranes related to subduction of the Neo-Tethys oceanic slab. Three generations of cassiterite have been identified with distinctive cathodoluminescence textures and trace element patterns, indicating the episodic input of ore-forming fluids and distinctive changes in the physical-chemical conditions of the Kuntabin magmatichydrothermal system. Sudden changes of fluid pressure, temperature, pH, etc., may have facilitated the deposition of Sn and W. Rhenium contents of molybdenite from the Kuntabin deposit and many other Sn-W deposits in Myanmar are characteristically low compared to porphyry Cu-Mo-(Au) deposits worldwide. In combination with zircon Hf isotope signatures, we infer that granites associated with Sn-W deposits in Myanmar were predominantly derived by melting of ancient continental crust and contain minimal mantle contribution.Subduction of the Neo-Tethys oceanic slab from west of the West Burma terrane reached beneath the Sibumasu terrane and led to magmatism and Sn-W mineralization at ~90 Ma when the Kuntabin deposit was formed. The Paleoproterozoic Sibumasu crust was activated during the subduction-related magmatism to form predominantly crust derived melts. After a high degree of fractional crystallization and fluid exsolution, physical-chemical changes of the hydrothermal fluid resulted in Sn and W precipitation to form the Kuntabin Sn-W deposit.

Effect of eutectic reaction between depositing atoms and substrate elements on morphological evolution of Sn–Bi–Sn multilayer deposition

In this work, we studied the effect of the reaction between the depositing atoms and the substrate element on the morphological evolution of the each deposition of the Sn–Bi–Sn multilayer structure on the Cu substrate. For the deposition of the single Sn layer on the Cu substrate, the reaction between the depositing Sn atoms and the Cu substrate is very minimal. TEM study shows only a very thin interfacial Cu–Sn compound layer (17 nm) formed between the depositing Sn layer and the Cu substrate. Yet, the latent heat of the vaporized Sn (296.1 kJ/mol) melts the Sn deposition layer on the Cu layer. Owing to the surface tension of the molten Sn, the molten Sn could agglomerate as the Sn clusters for reducing the surface energy.For the subsequent deposition of Bi and Sn layers, the eutectic reaction would occur between the depositing Bi atoms and the Sn clusters. The energy required for the eutectic reaction between the depositing atoms and the substrate elements is provided by the latent heat released from the vaporized Bi (or Sn) atoms arriving on the deposition surface. The eutectic liquid formed on the deposition surface serves as a medium to (1) receive and redistribute the depositing atoms and (2) dissolve and transport the substrate elements. The above process (1) and (2) explain the morphological evolution of the each deposition of the Sn–Bi–Sn multilayer structure and the mechanism of morphological evolution is proposed in this work.

High lithium anodic performance of reduced Sn particles on Co metal-organic frameworks for lithium-ion batteries with a long-cycle life

In recent years, lithium-ion batteries (LIBs) have become the battery technology of choice for portable devices, electric vehicles and grid storage due to their superior electrochemical performance and portability. Despite the successful commercialization of lithium-ion batteries in portable electronic devices, intensive research on high-energy density anode materials for lithium ion batteries is still ongoing to meet the ever-increasing high energy demand for upcoming advanced self-powering smart portable electronics and large-scale applications ranging from electric vehicles to power grids. In this regard, Surfactant-assisted cobalt metal-organic framework is synthesized through a solvo-thermal method and after Sn deposition uses as an anode in lithium-ion batteries. Using PEG400 resulted in a MOF with different trigonal (rhombohedral) lattice while a monoclinic structure is obtained when no surfactant is used. The presence of PEG400 polymeric surfactant with its role of orientation leads to the creation of special structural order and creates an array of structural units with a trigonal network (rhombone), which is completely different from the composition, creates in the same synthesis conditions with monoclinic structure. Different electrochemical behavior toward lithium insertion/extraction is attributed to different atomic packing factor. The trigonal structure synthesized at the presence of PEG400 shows better electrochemical performance compared to MOF1 at the absence of surfactant. Discharging capacity of the trigonal structure in the first cycle is about 615 mA h.gr−1, which is increased by 3% in the second cycle and reaches 634 mAhgr−1. Also, the amount of discharging capacity in 207 cycles is reduced to about 400 mAhgr−1, which results in approximately twice the electrochemical performance of the pure tin and tin-cobalt alloy synthesized anodes by the electrochemical method and also indicates superior electrochemical performance in comparison with common graphite anodes.

Electrical Resistivity of Ni–Fe Wires Coated with Sn Using low-Pressure Chemical Vapor Deposition

In this study, we demonstrated that the deposition of Sn on Ni–Fe wires using low-pressure chemical vapor deposition (LPCVD) can be used to control the electrical resistivity of the wires. Furthermore, the effect of the deposition temperature on the resistivity of the Ni–Fe wires was investigated. The resistivity of the Sn-deposited Ni–Fe wires was found to increase monotonically with the deposition temperature from 550 to 850 °C. Structural and morphological analyses revealed that electron scattering by Ni3Sn2 and Fe3Sn particulates, which were the reaction products of LPCVD of Sn on the surface of the Ni–Fe wires, was the cause of the resistivity increase. These coalesced particulates displayed irregular shapes with an increase in the deposition temperature, and their size increased with the deposition temperature. Owing to these particulate characteristics, the Sn content increased with the deposition temperature. Furthermore, the temperature dependency of the Sn content followed a pattern very similar to that of the resistivity, indicating that the atomic content of Sn directly affected the resistivity of the Ni–Fe wires.

Fragment of a central-type large structure located in southern Uganda and its metallogenic value

For the southern regions of Uganda, the metallogenic value of the regional arc belt of dikes of the main and ultrabasic composition was considered. It is shown that it is part of the arc sector of a large central-type structure with a diameter of about 700 km. It had a long development in the Riphean sequence of tectono-magmatic activation. This structure was formed over 1,37 billion years ago and reformed approximately 1 billion years ago and at the end of the Riphean sequence (0,5—0,6 billion years ago).This structure includes all major deposits of Sn, W, Na, Nb, Ni, REE and Au in Burundi, Congo, Rwanda, Tanzania and Uganda. In Uganda, the Sn, W and rare metals fields are controlled by small intrusions of granite with an age of 1 billion years and crossing nodes of radial faults, which are the central-type structures of small order that are included in the central part of the allocated megastructure. Materials in the relationship of ore-grade gold mineralisation with the crossing nodes of large arc, radial and overfault-shift faults are given.

Mechanical Properties of Solder-Jointed Copper Rods with Electrodeposited Sn-Zn Alloy Films.

Enforced solid solution type Sn-Zn alloy films were electrochemically synthesized on Cu substrate from an aqueous solution containing citric acid complexes. The electrodeposition behavior of Sn-Zn alloys was classified to a normal co-deposition type, in which electrochemically nobler Sn deposits preferentially compared to Zn. Electrodeposited Sn-Zn alloy films were composed of a non-equilibrium phase, like an enforced solid solution, which was not observed in an equilibrium phase diagram of an Sn-Zn binary alloy system. By applying a thermal annealing process at 150 °C for 10 minutes, a pure Zn phase was precipitated from an electrodeposited Sn-based solid solution phase with excessively dissolved Zn atoms. During the soldering process, intermetallic phases such as Cu3Sn and Cu5Zn8 were formed at the interface between an Sn-Zn alloy and Cu substrate. Tensile strength and fracture elongation of solder-jointed Cu rods with Sn-8 at.%Zn alloy films reached ca. 40 MPa and 12%, respectively.

Discrete Jurassic and Cretaceous Mineralization Events at the Xiangdong W(-Sn) Deposit, Nanling Range, South China

Abstract The Xiangdong W(-Sn) deposit is hosted in the Dengfuxian multiphase granites (biotite, two-mica, and muscovite granites) within the Nanling Range metallogenic belt in south China. Previous studies suggested that the W(-Sn) mineralization in the Xiangdong deposit is related to the Late Jurassic two-mica granite, whereas recently W-Sn–bearing quartz veins have also been identified in muscovite granite. We present new cassiterite and zircon U-Pb ages to constrain the timing of W-Sn mineralization and related granitic magmatism. Our laser ablation-inductively coupled plasma-mass spectrometry U-Pb dating of zircon grains, combined with previous zircon ages, in addition to the trace element composition of the muscovite granite, suggest the muscovite granite in the Dengfuxian pluton was emplaced at 145 to 142 Ma and shows highly evolved features. Cassiterite grains from the ore-bearing veins in two-mica granite yielded U-Pb ages of 151.6 ± 3.7 and 141 to 138 Ma, whereas cassiterite grains from quartz veins occurring in muscovite granite yielded a U-Pb age of 136.8 ± 3.3 Ma. The new ages and detailed geologic evidence indicate that the Early Cretaceous muscovite granite is also genetically related to W-Sn mineralization. Combining this with previously published data from the Late Jurassic two-mica granites and related mineralization, we suggest that there were two stages of W-Sn mineralization at Xiangdong. Arsenopyrite geothermometry from the two stages suggests temperatures of 300° to 491° and 308° to 450°C in stage I and stage II, respectively. Wolframite grains from the two stages also show different characteristics and patterns for their major and trace elements. The enrichment in Sc in wolframite suggests low-pH and low-Eh conditions for a fluid containing F– and/or PO43− complexes during stage I, whereas higher contents of Nb and Ta and lower contents of Sc in wolframite from stage II indicate relatively lower pH and higher Eh conditions. In combination with data from other recent studies, we propose that the 145 to 130 Ma interval represents a newly recognized W-Sn metallogenic period linked with highly evolved granites in the Nanling Range metallogenic belt. The Early Cretaceous muscovite granite is an important new target for W and Sn resources in south China.

Thermal Cycling Study of Electrodeposited Sn–Ni and In–Ni Alloys

We report the electrochemical deposition of Sn–Ni and In–Ni alloys containing 20 and 45 wt % of the lower melting point component. The percentage of nickel in the deposited alloys has been determined by gravimetric analysis. We have studied the thermal behavior of the deposited materials in heating–cooling cycles in the temperature ranges 50–250, 50–300, and 50–400°C. The results of this study can be useful in high-density mounting using Pb-free solder materials with a preset soldering temperature.

Nucleation and growth mechanism of tin electrodeposition on graphene oxide: A kinetic, thermodynamic and microscopic study

Nucleation and growth mechanism of Sn deposition over graphene oxide (GO) was investigated by cyclic voltammetry, chronoamperometry and transmission electron microscopy (TEM) using an aqueous electrolyte containing 10 mM SnSO4 at pH 2.0. Chronoamperometry studies revealed adsorption phenomena of Sn atoms over GO electrode before the nucleation. Simultaneous reactions that happened over the GO electrode were hydrogen ion reduction along with 3D diffusion-controlled nucleation and growth of Sn. The reaction rates of nucleation and hydrogen reduction increased with increase in the applied potential towards more negative values. Application of atomistic theory of nucleation revealed the fact that a supercritical nucleus can be formed even with one Sn atom over GO sheet which implied that every single atom of deposited Sn can act as a stable nucleus which can grow with further addition of Sn atoms. Further application of classical nucleation theory suggested that the thermodynamic activation energy barrier for nucleation under the applied potential ranges is comparable to that of room temperature thermal energy, kT (2.476 kJ/mol) implying that the deposition was heavily governed by formation of initial adsorption layer of Sn adatoms. Characterization of surface morphology, size and distribution of Sn nanoparticles over GO was performed using TEM and a quantitative comparison of number density of nucleation sites has been presented.

Akopovaite, Li2Al4(OH)12(CO3)(H2O)3, a new Li member of the hydrotalcite supergroup from Turkestan Range, Kyrgyzstan

AbstractAkopovaite, ideally Li2Al4(OH)12(CO3)(H2O)3, is a new hydrotalcite-supergroup mineral from the Karasu–Karavshinskoye Sn deposit, Turkestan Range, Kyrgyzstan. It occurs as white or pale yellowish rosette-like aggregates that are composed of tiny curved plates up to 20–30 μm. Akopovaite is associated with gibbsite, quartz, albite, microcline, muscovite, montebrasite, siderite, schorl and birnessite-like Fe–Mn oxides. Akopovaite has a perfect cleavage along {001}, the mineral is transparent and very soft (VHN = 24 that corresponds to Mohs hardness of ca. 1). Dmeas = 2.12(2) g/cm3 and Dcalc = 2.106 g/cm3. The Raman spectra contain bands of carbonate groups and bands of O–H stretching vibrations. The chemical composition (wt.%, electron microprobe for Al and Fe; ICP-OES for Li; CHN method for CO2 and H2O) is Li2O 6.43, Al2O3 45.79, Fe2O3 0.27, CO2 10.09, H2O 36.1, total 98.68. The empirical formula based on (Li + Al + Fe) = 6 apfu is Li1.94(Al4.05Fe0.02)Σ4.07(OH)12(CO3)1.03(H2O)3.03. The crystal structure was refined by the Rietveld method with RB = 0.006 and Rwp = 0.014. Akopovaite is monoclinic, C2/m, a = 5.0953(6), b = 8.877(1), c = 7.806(1) Å, β = 102.572(6)°, V = 344.61(8) Å3 and Z = 1. The polytype should be denoted as 1M. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 7.66(100)(001), 4.397(27)(020), 3.821(45)(002,021), 2.4881(27)(200), 2.2273(16)(201) and 1.9027(18)(202). Akopovaite is the first naturally occurring hydrotalcite-supergroup carbonate species of Al and Li; its synthetic analogue is known.

Genesis and timing of the Sungai Lembing tin deposit in Pahang, East Malaysia: Constraints from LA–ICP–MS zircon and cassiterite U–Pb dating, geochemical compositions and Sr–Nd–Hf isotopes

The Sungai Lembing tin (Sn) deposit is one of the largest primary Sn deposits in Malaysia, and is a typical hydrothermal vein-type deposit with strong spatial and genetic relationship with the underlying granites. In-situ LA-ICP-MS cassiterite U-Pb dating of the Sn-bearing polymetallic sulfide stockworks yields a weighted average age of 264.2 ± 2.0 Ma, consistent to the zircon U-Pb ages (ca. 260.3–263.0 Ma) for the granites there, showing that the Late Permian mineralization was co-magmatic. The ore-related granites are featured by high SiO2, Al2O3, Na2O, K2O, and low P2O5 contents, with low A/CNK ratios, indicating that these granites are peraluminous I-type high-K calc-alkaline. These granites are enriched in Rb, U, Nd, Zr, Hf and light rare earth elements (LREEs), and relatively depleted in Ba, Nb, Sr, P, Ti and heavy rare earth elements (HREEs), accompanied by negative Eu anomalies. The relatively low whole-rock initial 87Sr/86Sr ratios (0.704199–0.708692), moderately high εNd(t) (−5.30 to −1.88), and old two- stages Nd model ages (1.05–1.28 Ga), together with the negative zircon εHf(t) (−3.2 to −0.3) and old two-stages Hf model ages (1.29–1.48 Ga), indicate that the granites were sourced from the magma generated by the partial melting of Proterozoic meta-igneous rocks of the Indochina Block. The extensive emplacement of Permian granites and Sn mineralization in the Eastern Granite Belt of Peninsular Malaysia may have been resulted from the east-dipping subduction of the Paleotethys beneath the western Indochina Block.

The Permian Sn metallogenic event and its geodynamic setting in East Kunlun, NW China: Evidence from zircon and cassiterite geochronology, geochemistry, and Sr–Nd–Hf isotopes of the Xiaowolong skarn Sn deposit

Abundant granitoids are exposed along the East Kunlun orogenic belt (EKOB), and many skarn deposits occur at the contacts between intrusions and strata. One such is the Xiaowolong deposit, a skarn-type tin polymetallic deposit that is temporally and spatially associated with porphyry monzogranite. Tin mineralization is mainly hosted by the skarn. In this study, we reported zircon and cassiterite U–Pb ages, whole-rock geochemistry, and Sr–Nd–Hf isotopic data, and used these to constrain the timing of intrusion and mineralization in the Xiaowolong deposit and identify the origin of the ore-related granites and the link between Sn mineralization and granitic magmatism. Age determinations by LA-ICP-MS U–Pb zircon dating indicated that the porphyry monzogranite formed at 260.0 ± 0.7 Ma. Cassiterite from the ore-bearing skarn yielded a Tera-Wasserburg U–Pb lower intercept age of 258.0 ± 3.7 Ma. These ages suggested that both granitic intrusion and related Sn mineralization in the Xiaowolong deposit were initiated during the Permian (ca. 260 Ma). The porphyry monzogranites had high SiO2 (71.26–73.13 wt%) and Al2O3 (13.84–14.46 wt%) contents, were alkali-enriched (K2O + Na2O = 7.08–7.69 wt%), had A/CNK values that ranged from 1.01 to 1.05, were enriched in light REEs and large ion lithophile elements such as Rb, Th, U and K, were depleted in high field strength elements, and had relatively low Zr, Nb, Y and Ce contents. They thus exhibited the geochemical characteristics of I-type granite. The porphyry monzogranite had consistent negative whole rock ɛNd(t) (−6.8 to −7.1) and magmatic zircon ɛHf(t) values ranging from −7.4 to −1.6, and two-stage Hf model ages ranging from 1393 Ma to 1758 Ma. Detailed elemental and isotopic data demonstrated that the porphyry monzogranite were derived from partial melting of ancient crustal source, and emplacement in a subduction tectonic setting. The Xiaowolong tin mineralization event indicated that the EKOB has great potential for exploration focusing on Permian-Triassic Sn skarn deposits.

Zircon U–Pb and Sm–Nd geochronology and geochemistry of the Sn–W deposits in the northern Guposhan ore field, Nanling Range, southern China

The Guposhan ore field, located in the central part of the Nanling Range and close to the giant Central South Peninsula tin ore belt, is well-known for its large-scale Sn (W) mineralization and hosts a series of middle to large scale Sn (W) deposits. In this study, medium to fine grained biotite granite, outcropped in the mining area, have zircon U–Pb ages of 162.8 ± 1.3 Ma (MSWD = 0.54) and 162.7 ± 1.2 Ma (MSWD = 0.66), respectively. These zircon ages are consistent to the Sm–Nd isotopic age of minerals (garnet, hornblende, clinopyroxene and orthopyroxene) from the skarn-type ores, which is 160.4 ± 4.8 Ma (MSWD = 1.3). These granites are characterized by high content of SiO2, K2O, Na2O and REEs, and high Ga/Al ratios, indicating that they belong to highly fractionated A-type granites with high-K calc-alkaline and aluminous-peraluminous signatures. The zircon Lu–Hf isotopes of these granites have εHf(t) values and TDMC ages of −2.66 to −1.71 and 1.32–1.38 Ga, respectively. Combined with the previous studies, it was proposed that the magma was formed by the mixing of crust-mantle components (ca. 50 and ca. 50%, respectively). In addition, magmas are characterized by low temperatures of ca. 710 °C and oxygen fugacity (log(fO2) values of −18.5 to −16.4. Formation of these granites were likely related to an intraplate extensional tectonic setting, triggered by roll-back of the subducted Paleo-Pacific plate beneath the South China Block (SCB). These granites are in favor of the Sn (W) mineralization, making the Guposhan ore district a large-scale Sn (W) mineralization ore field in the Nanling Range.

Local confinement and alloy/dealloy activation of Sn–Cu nanoarrays for high-performance lithium-ion battery

The practical application of Sn-based anodes are seriously hampered by the dramatic volume expansion (∼300%) during charge/discharge processes, which induces large internal stress that can make the anode materials easily pulverized and cracked to cause the loss of electrical contact and thus severe capacity fading. In order to address this problem, a versatile strategy has been developed for preparing multiple Sn/Cu nanoarrrays including Cu–Sn end-to-end nanowires (NWs), Cu@Sn core-shell NWs and Cu@Sn core-shell semi-nanotubes (NTs) through a two-step successive-electrodeposition process with track-etched polycarbonate (PC) membranes as template: metallic Cu nanowire arrays are first electrodeposited inside the nanopores of the PC membrane on the Cu foil substrate, followed by the deposition of Sn in the second step. The architectures of these samples can be readily tuned by modifying the synthesis conditions or by treating the PC membrane with 3-aminopropyl-triethorxysilane (APTES). The distinct structures of these electrodes provide a high performance in lithium ion batteries. The discharge capacity of Cu–Sn NWs, Cu@Sn NWs, and Cu@Sn NTs after 400 charge-discharge cycles at a specific current of 0.8 A g−1 is 714, 402, and 1193 mA h g−1, respectively. Such a performance can be attributed to a local confinement effect between Sn and Cu maintaining structural integrity and good electrical contact, and an alloy/dealloy activation process achieving high reversible capacities.

Self-catalytic-grown SnOx nanocones for light outcoupling enhancement in organic light-emitting diodes

Light extraction in organic light-emitting diodes (OLEDs) was improved by applying SnOx nanocones grown via thermal annealing in a low-O2 atmosphere. SnOx was easily fabricated through thermal processing after Sn deposition. The diameter of the SnOx nanocones was controlled by changing the deposition thickness of Sn. The SnOx nanocones induced strong Mie scattering, which reduced the total internal reflection in the glass substrate. Consequently, the OLED with SnOx nanocones exhibited a 23% increase in the external quantum efficiency compared with a reference device.