Pb Deposition Research Articles

LONG-RANGE ATMOSPHERIC TRANSPORT OF RADON IN EAST ASIA AND DEPOSITION OF ITS PROGENIES IN JAPAN.

A three-dimensional long-range atmospheric transport model for 222Rn and its progenies was applied to simulate 210Pb deposition in Japan and its adjacent waters. Monthly precipitation and 210Pb deposition simulated by the model for winter months were favorably compared with observational data although they were exceptionally underestimated in Aomori. The large monthly deposition along the Japan Sea coast lines during winter was successfully simulated by the model to be nearly 200Bqm-2, which was contrasted by about 10-fold smaller deposition in other regions. It was also pointed out that the heavy deposition areas formed a narrow band structure along the coastline with width of several tens of kilometers and 210Pb deposition amount positively correlated with the height of mountains located leeward of the heavy deposition areas.

ANALYSIS OF 210PB DEPOSITION DISTRIBUTION CHARACTERISTICS IN WINTER AT ROKKASHO IN AOMORI BASED ON HIGH RESOLUTION ATMOSPHERIC TRANSPORT/DEPOSITION MODEL CALCULATION.

To evaluate 210Pb deposited on the surface of sea around Japan in detail, the performance of atmospheric transport/deposition model for 222Rn and its progenies was examined. To test the model's reproducibility of 210Pb deposition in winter, it was applied at Rokkasho in Aomori, where the model had been reported to significantly underestimate when the horizontal grid interval of 9km was used. It was shown that the precipitation on the Pacific Ocean side and Mutsu Bay and hence the 210Pb deposition at Rokkasho were significantly improved with the grid interval of 3km although the deposition was still underestimated by the observation. This underestimation was considered to be caused by model's neglect of horizontal drift of snow and rain. It was also pointed out that the deposited 210Pb was mainly contributed by the lower atmosphere up to 2-3km.

Provenance of Anthropogenic Pb and Atmospheric Dust to Northwestern North America.

Industrial activities release aerosols containing toxic metals into the atmosphere, where they are transported far from their sources, impacting ecosystems and human health. Concomitantly, long-range-transported mineral dust aerosols play a role in Earth’s radiative balance and supply micronutrients to iron-limited ecosystems. To evaluate the sources of dust and pollutant aerosols to Alaska following the 2001 phase-out of leaded gasoline in China, we measured Pb-Sr-Nd isotopic compositions of particles collected in 2016 from snow pits across an elevational transect (2180–5240 m-a.s.l) in Denali National Park, USA. We also determined Pb flux and enrichment from 1991–2011 in the Denali ice core (3870 m-a.s.l). Chinese coal-burning and non-ferrous metal smelting account for up to 64% of Pb deposition at our sites, a value consistent across the western Arctic. Pb isotope ratios in the aerosols did not change between 2001 and 2016, despite the ban on lead additives. Emissions estimates demonstrate that industrial activities have more than compensated for the phase-out of leaded gasoline, with China emitting ∼37,000 metric tons year–1 of Pb during 2013–2015, approximately 78% of the Pb from East Asia. The Pb flux to Alaska now equals that measured in southern Greenland during peak pollution from North America.

Characterization and genesis of supergene karstic vanadium ores in the Djebba Pb–Zn district (Triassic Diapirs zone, North Eastern Tunisia)

The Djebba district hosts hypogene Pb–Zn sulfides and two successive stages of supergene Pb–Zn–Fe–V mineralization. This study mainly focuses on the supergene karstic vanadium mineralization of Jebel Goraa deposit. The hypogene Pb–Zn mineralization is considered to have been formed during Late Miocene (Alpine Orogeny) by Mississippi-Valley-Type (MVT) brines, similar to that proposed for many other Pb–Zn ore deposits of the Diapirs zone in Northern Africa. During the Late Neogene-Pleistocene, several episodes of uplift and erosion enabled the exhumation and karstification of the Early Eocene host rocks, and spatially related hypogene Pb–Zn-(Fe) sulfides, their subsequent weathering, and the formation of supergene ores. Vanadium mineralization is developed in karst cavities filled with oxidized ores (goethite, smithsonite and hemimorphite) and argillaceous materials (smectite). The paragenesis of supergene ores reveals two successive stages of deposition: 1) early supergene weathering with formation of Fe-bearing carbonates in turn oxidized to goethite, smithsonite, hemimorphite, and cerussite; 2) late supergene weathering with deposition of Pb–Zn vanadate minerals (vanadinite, descloizite, and vanadinite-pyromorphite intermediate compositions), minor mimetite and late calcite.Vanadium, phosphorous and probably chlorine of the vanadate ores are inferred to have originated from the immature organic matter of Early Eocene country rocks (Tmax <435 °C and TOC average 3.4 wt%) by descending low-temperature aqueous solutions. Pb, Zn and minor As were derived from primary Pb–Zn sulfides undergoing oxidation. Genesis of supergene vanadium ores is genetically related to post-Miocene uplifting-related weathering episodes, controlled by tectono-morphological and climatic evolution following the Alpine orogeny. The formation of the vanadium mineralization spans through the Late Miocene to Holocene. However, with paleoclimatic considerations it could be generally confined to the Middle Pliocene. Genetically, the supergene vanadium ores of Djebba Pb–Zn district belong to the vanadate ores type, which have been reported in other areas of southern and northern Africa (e.g., Namibia and Morocco). The association of vanadium, particularly in highly fractured and faulted zones with high levels of immature organic matter and spatially close to surface or near-surface MVT Pb–Zn ore deposits, can be used as an exploration tool for new vanadium-bearing deposits.

Green Electrorefining of Crude Lead with High-Quality Deposits in an Additive-Assisted Methanesulfonic Acid System

The conventional electrorefining process of crude lead (Pb)─employing a bone glue (BG)- and calcium lignosulfonate (CL)-synergistically assisted fluosilicic acid (H2SiF6) system─suffers the undesired environment burden caused by the high saturated vapor pressure and low stability of H2SiF6. Herein, we propose an additive-assisted methanesulfonic acid (MSA) system for green and efficient electrorefining of crude Pb based on the low volatility and high stability of MSA. Combinations of MSA with additives are evaluated and screened using photographic images, SEM observations, XRD, white light interference, etc. The electrochemical analysis of cyclic voltammetry and chronoamperometry elucidates the Pb deposition behavior in the Lugalvan BNO12-assisted MSA system, in which a three-dimensional nucleation model is applicable. Using MSA as the solvent and β-naphthol ethoxylate (Lugalvan BNO12) as the assisted additive, the bench-scale operation of crude Pb electrorefining experimentally achieves an electric energy requirement (W) of 87 kWhe/t Pb and a cathodic current efficiency (η) of 99.6%. This is very competitive with the W of 120 kWhe/t Pb and η of 95.0% for the BG-CL-assisted H2SiF6 system. Also, the bench-scale operation obtains a plat and dense deposit sample with a Pb purity of >99.99%. The distribution behavior of elements shows that most of the Pb element is recovered in the form of the cathodic Pb, elements Sn, Zn, and Fe mainly accumulate in the electrolyte, and elements As, Sb, Bi, Ag, and Cu remain in the anode slime. This work opens new directions for more technically and economically feasible Pb electrorefining.

European mammal exposure to lead from ammunition and fishing weight sources

Ammunition and fishing weight usage is the greatest largely unregulated contributor of lead (Pb) deposition to the European environment. While the range of negative impacts of Pb exposure to humans and avian wildlife are relatively well documented, little is known about risks to wild mammals despite recent scientific interest and publications. A qualitative risk assessment of the potential Source-Pathway-Receptor linkages for European mammal exposure was conducted, based on literature reviews and existing evidence and discussions with experts from the fields of wild mammal feeding ecology, behaviour and health.The assessment identified 11 pathways for mammal exposure to Pb, with all 243 European species likely to be potentially exposed via one or more of these. All species were identified as potentially exposed via ingestion of water with elevated Pb from degraded ammunition/fishing weights. Ingestion of vegetation with elevated Pb from degraded ammunition/fishing weights potentially exposed many species (158), 78% of which had a potentially high risk of exposure when feeding in areas of high Pb deposition. Ingestion of retained ammunition in previously shot prey and/or discarded kill/gut piles with embedded ammunition was another significant pathway, contributing to predatory and scavenging carnivorous mammal exposure where an individual exposure event would be expected to be high.The mechanisms by which Pb from ammunition and fishing weight sources are moved up trophic levels and ‘transferred’ from areas of high deposition into wider food chains e.g. via water, flying invertebrates and herbivores being subsequently preyed upon requires further investigation.In conclusion, there are multiple and diverse Source-Pathway-Receptors linkages for European mammal exposures to Pb and evidence of exposure, from Europe and elsewhere, exists for some herbivores, carnivores, omnivores and insectivores. Both fatal but more likely non-fatal chronic and acute exposures may be expected to occur in wild European mammalian species, including those in poor conservation status.

Pb-isotope systematics at the Sopokomil shale-hosted massive sulfide deposit, North Sumatra, Indonesia

Sopokomil is the best-explored shale-hosted massive sulfide Zn–Pb deposit on the Sumatra Island, Indonesia. At present, it is the most economically viable Zn–Pb deposit on the island. To understand the origin and metal sources of the deposit, Pb-isotope data were collected from galena in the Sopokomil stratiform ore. The data, which were acquired by laser ablation multi-collector inductively coupled mass spectrometry, showed highly radiogenic Pb-isotope ratios (206Pb/204Pb = 18.976 ± 0.010, n = 120; 207Pb/204Pb = 15.825 ± 0.009, n = 120; 208Pb/204Pb = 38.928 ± 0.016, n = 120) that are strongly correlated with one another (r = 0.58–0.99). Statistical analysis using analysis of variance and Welch’s t-test indicated that the Pb-isotope ratios are inhomogeneous, at both the inter-horizon and the intra-horizon levels. The results suggest that Pb in the Sopokomil ore deposit likely originated from the upper crust.

The Underpotential Deposition of Lead and its Effect on Carbon Monoxide Adsorption on Pt(111) Electrode

In situ scanning tunneling microscopy (STM) was used to examine the spatial structures of lead (Pb) adatom and carbon monoxide (CO) molecule adsorbed onto an ordered Pt(111) electrode in 0.1 M perchloric acid (HClO4) containing 1 mM Pb(ClO4)2 under potential control. Ordered Pb structures were not seen until the potential was made more negative to 0 V (vs Ag/AgCl), where a quasi-square array (√7 × √57) was seen. Shifting the potential more negative substantiated Pb deposition, which triggered restructuring of the Pb adlayer into (√21 × √21)R11° and (3 × 2√3)rect (θ = 0.62 and 0.67) at −0.1 V. Pb adatom reduced the poisoning effect of CO on the Pt(111) electrode by blocking the adsorption of CO and by forcing CO molecule to asymmetric sites. An ordered (√7 × 3)—Pb + CO structure was imaged at 0 V in 0.1 M HClO4 + 1 mM Pb(ClO4)2, from which the surface coverage and binding sites of CO molecule were inferred.

Cu-mediated optimization of PbO2 anodes for electrochemical treatment of electroless nickel plating wastewater

Effective removal of Ni(Ⅱ)-organic complexes from electroless nickel plating wastewater remains a challenge by conventional industrial effluent treatment processes. In this study, electrochemical oxidation using a PbO2 anode is proposed for effective decomplexation of Ni-organic complexes. The electrode quality and electrocatalytic capability of the PbO2 anode is shown to be greatly affected by the nature of the PbO2 active layer that is formed during the electrodeposition process with the current density, cathode material and electrolyte constitutions all exerting an influence on the Pb deposition behavior. Our investigations reveal that the presence of Cu2+ in the electrolyte can precisely control the amount of elemental Pb formed with Pb cathodic reduction and deposition prevented as a result of preferential Cu0 deposition. The doping of PbO2 with Cu significantly improved the morphology and electrocatalytic performance of the PbO2 deposit. Ni-citrate and TOC removal percentages of 83 % and 55 % respectively were achieved with the optimal Cu-doped PbO2 anode with 73 % of the Ni recovered at the cathode at a relatively low specific energy consumption of 12.7 kWh m−3. A possible mineralization pathway of Ni-citrate by the PbO2 anodic oxidation process is proposed.

Photocatalytic Deposition of Nanostructured CsPbBr3 Perovskite Quantum Dot Films on Mesoporous TiO2 and Their Enhanced Visible-Light Photodegradation Properties.

Herein, we report the in situ photocatalytic deposition of cesium lead bromide (CsPbBr3) perovskite quantum dots on mesoporous TiO2-coated fluorine-doped tin oxide (FTO/TiO2) electrodes. The mesoporous TiO2 layer is used as a photocatalyst to promote the following: (1) the Pb deposition from a Pb2+ aqueous solution and (2) the in situ Pb conversion into CsPbBr3 perovskite in the presence of a CsBr methanolic solution without any organic capping agent. Both steps are carried out under ultraviolet light irradiation under ambient conditions without any post-treatment. The obtained FTO/TiO2/CsPbBr3 film was characterized by UV–vis diffuse reflectance spectroscopy, X-ray diffraction, photoluminescence spectroscopy, scanning electron microscopy, and transmission electron microscopy. The FTO/TiO2/CsPbBr3 heterojunction exhibited enhanced visible-light photodegradation activity demonstrated for the oxidation of curcumin organic dye as a model system. The novel and simple approach to fabricating a supported photocatalyst represents a scalable general method to use semiconductors as a platform to incorporate different perovskites, either all-inorganic or hybrid, for optoelectronic applications. The perovskite deposition method mediated by the UV light at room temperature could be further applied to flexible and wearable solar power electronics.

Sequence stratigraphy of the ca 1640 Ma Barney Creek Formation, McArthur Basin, Australia

The ca 1640 Ma Barney Creek Formation is a mostly fine-grained silicicastic unit of the McArthur Group in the southern McArthur Basin of northern Australia. It is one of the most prospective units for clastic-dominated (CD-type) Zn–Pb deposits in the world, hosting the giant McArthur River Zn–Pb–Ag and the Teena Zn–Pb deposits. The Barney Creek Formation records deposition of dominantly dolomitic siltstone turbidite facies at or below storm wave base. These strata were deposited in a series of sub-basins and on submerged paleohighs that formed in response to roughly north–south extension during early Barney Creek times. A detailed, regional-scale sequence stratigraphic analysis based on 20 wells indicates that the middle McArthur Group (Emmerugga Dolostone to Lynott Formation) comprises six third-order depositional sequences, of which the Barney Creek Formation includes two (named B1 and B2). These two sequences and the overlying sequence L1 (Reward Dolostone and lower Lynott Formation) record significant lateral facies and thickness changes across the southern McArthur Basin. These variations can be explained by a geographical shift in the depocentre during structural re-organisation of the basin. The depocentre migrated from the south, where accommodation was mostly created during deposition of sequence B1, towards the north during deposition of sequence B2. KEY POINTS Sequence stratigraphic analysis of the Barney Creek Formation on a regional scale based on 20 wells. Barney Creek Formation includes two third-order depositional sequences (named B1 and B2), which record significant lateral thickness and facies shifts. Thickness and facies shifts can be explained by geographical shift of depocentre from the present-day south to north.

Effects of Selenium Supplementation on the Ion Homeostasis in the Reproductive Organs and Eggs of Laying Hens Fed With the Diet Contaminated With Cadmium, Lead, Mercury, and Chromium

The objective of this study was to explore the toxic effects of different heavy metals in combination with their deposition and ion homeostasis in the reproductive organs and eggs of laying hens, as well as the alleviating action of selenized yeast. A total of 160 Lohmann pink-shell laying hens (63-week-old) were randomly allocated into four treatments with 10 replicates of four hens each. The four dietary treatments were the corn-soybean meal basal dietary (control; CON); the CON dietary supplemented with 0.4 mg/kg selenium from selenized yeast (Se); the CON dietary supplemented with 5 mg/kg Cd + 50 mg/kg Pb +3 mg/kg Hg + 5 mg/kg Cr (HEM), and the HEM dietary supplemented with 0.4 mg/kg selenium from selenized yeast (HEM+Se). The dietary HEM significantly increased Cd, Pb, and Hg deposition in the egg yolk and ovary, and Cd and Hg deposition in the oviduct and in the follicular wall (p < 0.05). The HEM elevated Fe concentration in the egg yolk, ovary, and oviduct (p < 0.05). The HEM decreased Mn concentration in the egg yolk, Fe, Mn, and Zn concentrations in the egg white, Cu concentration in the ovary, Mg concentration in the oviduct, as well as Ca, Cu, Zn, and Mg concentrations in the follicular walls (p < 0.05). Dietary Se addition elevated Se concentration in the egg yolk, oviduct, and follicular walls and Mg concentration (p < 0.05) in the oviduct, whereas it reduced Fe concentration in the oviduct compared with the HEM-treated hens. Some positive or negative correlations among these elements were observed. Canonical Correlation Analysis showed that the concentrations of Pb and Hg in the egg yolk were positively correlated with those in the ovary. The concentration of Cd in the egg white was positively correlated with that in the oviduct. In summary, dietary Cd, Pb, Hg, and Cr in combination caused ion loss and deposition of HEM in reproductive organs of laying hens. Dietary Se addition at 0.4 mg/kg from selenized yeast alleviated the negative effects of HEM on Fe and Mg ion disorder in the oviduct and follicle wall of hens.

Origin of the Bleaching in Lower Cretaceous Continental Red Beds in the Uragen Zn–Pb Deposit, Xinjiang, NW China, and Its Implications for Zn–Pb Mineralization

The Uragen giant sandstone-hosted Zn–Pb deposit has a proven reserve of 5.90 Mt metals in the southern ore zone and potentially 10 Mt metals for the whole deposit, and orebodies are strictly confined to the bleached clastic rocks of the Lower Cretaceous red beds. The bleaching has been used to guide lead–zinc exploration; however, its nature and origin, as well as the relationship with Zn–Pb mineralization, remains unclear, although it is closely related to regional oil–gas infillings. Detailed field investigation and petrographic observation, TESCAN-integrated mineral analyzer (TIMA), and X-ray fluorescence (μ-XRF) analysis of the red and bleached sandstone at the same sedimentary layer demonstrate that the bleaching is mainly caused by the reductive dissolution of hematite pigment, which probably resulted from the interaction with H2S formed by in situ sulfate reduction during hydrocarbon migration. The calcite cements in the bleached sandstones show δ13C and δ18O values of −5.36~−5.94‰ and 20.94~27.91‰, respectively, and these samples fall close to the evolution line of decarboxylation of organic matter in δ13C-δ18O diagram, also suggesting a genetic relationship between the bleaching and hydrocarbon-bearing fluids. Petrol–mineral composition changes and sulfide characteristics of red, bleached, mineralized zones, as well as pyrite locally replaced by coarse-grained galena in the mineralized zone, imply that the bleaching may occurred before Zn–Pb mineralization. Mass balance calculation and μ-XRF analysis indicate that large amounts of Fe and minor Zn were extracted from red beds with little or no sulfates; however, the red beds with abundant sulfates may be a sink for leached ore metals during the bleaching process. We therefore propose that the former accumulations of iron sulfides and reduced sulfur in the bleached zones may provide an ideal chemical trap for later Zn–Pb mineralization, and the bleached zones with high ∑S contents are the favorable prospective targets of the Uragen-style sandstone-hosted Zn–Pb deposits.

Unveiling the lead resistance mechanism and interface regulation strategy of Ru-based catalyst during chlorinated VOCs oxidation

Maintaining stable catalytic performance for chlorinated volatile organic compounds (CVOCs) oxidation in Pb-containing scenarios is an intractable challenge for the industrial application of Ru-based catalysts. Herein, we systematically investigated the effect of Pb poisoning on the activity over various Ru-based catalysts during the CVOCs oxidation and explored the possible Pb resistance mechanism. The source of high Pb resistance was clarified from two aspects: (1) oxygen vacancies on supports (CeO2 or TiO2) captured Pb and firmly locked it in lattice, namely strong capture effect; and (2) the formation of stable Ru-O-M (M = Ce and/or W) bonds weakened the affinity between active Ru sites and Pb, ensuring the preferential deposition of Pb at oxygen vacancies. With the synergistic effect of above factors, the intrinsic activity (mainly strong acidity) of Ru sites in Ru/CeO2 and RuW/TiO2 catalysts was retained, which ensured the efficient dissociation of C-Cl bond and oxidation of CB.

The Black Angel deposit, Greenland: a Paleoproterozoic evaporite-related Mississippi Valley-type Zn–Pb deposit

The Paleoproterozoic Mârmorilik Formation in the Karrat basin of West Greenland hosts the Black Angel Zn–Pb deposit. Chlorine-rich scapolite, zones with vuggy porosity and quartz nodules in the ore-bearing marble are herein interpreted to represent metamorphosed, vanished, and replaced evaporites, respectively. Mineralization is closely associated with anhydrite with δ34S values (5.2–12.6‰) broadly comparable to published values for Paleoproterozoic seawater sulfate. Considering the fundamental attributes of the mineralization and host sequence, a Mississippi Valley-type (MVT) model is the most obvious explanation for mineralization. Overlying the ore-bearing sequence are organic-rich semipelites and massive calcitic marbles, which may have served as seals for hydrocarbon or reduced sulfur and acted as chemical traps for deposition of the sulfidic ore. The Mârmorilik Formation contained an interlayered sulfate-rich evaporite-carbonate sequence, a common setting for MVT deposits in the late Neoproterozoic and Phanerozoic, but unique among the few known MVT deposits in the Paleoproterozoic. This ca. 1915 Ma evaporite-carbonate platform is younger than sulfate evaporites deposited during and immediately after the ca. 2220–2060 Ma Lomagundi carbon isotope excursion and records a significant seawater sulfate level during a time interval when it was assumed that it had been too low to form extensive evaporite deposits. Therefore, MVT and clastic-dominated (CD) Zn–Pb deposits in the geological record might progressively fill the apparent gap in marine sulfate evaporites and provide unique insights into Proterozoic seawater sulfate level. Considering the sequence of tectonic events that affected the Karrat basin, the mineralization took place between Nagssugtoqidian collision (< 1860 Ma) and Rinkian metamorphism (ca. 1830 Ma).

Sulphur and metal sources of polymetallic vein-type, sedimentary exhalative-type and Mississippi Valley-type Zn–Pb deposits along the southeast margin of the Yangtze Block

Three types of zinc-lead deposits, including polymetallic vein-type, sedimentary-exhalative (SEDEX), and Mississippi valley-type (MVT) Zn–Pb deposits, have been discovered along the southeast margin of the Yangtze Block. A systematically comparative study on the sulphur and metal sources for these deposits, is absent, which significantly limits the understanding of the metallogenic model and geological exploration. Thus, in order to reveal the S and Pb sources of Pb–Zn deposits, an investigation of trace elements of sphalerite and of S–Pb isotopic compositions of sulphides in these three types of Zn–Pb deposits was conducted in this study. We found that, in the vein-type, SEDEX, and MVT Zn–Pb deposits, (1) the sulphur was derived respectively from granitic magmatism related to the Guangxi Orogeny, early Cambrian stratified seawater and connate water; (2) the lead isotope variation indicates that the ore-forming metals were mainly derived from the granitic hydrothermal fluids for vein-type deposits, from basement rocks for SEDEX deposits, and mainly from early Cambrian sedimentary rocks for MVT mineralization. The Nanhua rifting lead to the syngenetic Zn-Pb mineralization, while the Guangxi Orogeny resulted in magmatic-hydrothermal vein mineralization at depth and in MVT mineralization at the shallow crustal levels.

Solid bitumen reflectance and authigenic clay mineralogy in relation to the Irankuh ore deposition: An innovative approach to basin analysis

This research investigates the relationship of petroleum generation and authigenic clay development in function of the paleo geodynamic setting and ore genesis of the Irankuh Zn–Pb deposit, Iran. Core samples from seven boreholes from the northern flank of the ore field, originating from the Gushfil, Rowmarmar, and Tappehsorkh mines, were studied by macro- and micro-petrography. Three important paleo-indicators of temperature, i.e. homogenization temperature of fluid inclusions (Th), Kübler Index (KI), and solid Bitumen Reflectance (BR) were used to constrain the geodynamic setting of the Irankuh deposit. The paleo-geothermal gradient is determined based on the correlation between KI and the inferred vitrinite reflectance (VR), and the maximum heating time is derived from a simulation study of VR versus Th. Results show that the ore mineralization occurred when Irankuh was located in a fore-arc setting during the Upper Cretaceous or Paleocene. The time of increased heat flux has been inferred to be more than one and likely below 10 million years. Zn–Pb mineralization is concentrated in zones enriched in residue solid hydrocarbon (RSH) which is a pyrobitumen type. Pyrobitumen represents a secondary byproduct of primary-oil solid bitumen reacting with hot hydrothermal mineralizing fluids. These interactions in an oil-water-rock system created secondary porosities that were filled by ores and authigenic clay minerals. Our evidence supported an epigenetic origin for ore formation in Irankuh. This study gives new insights into defining the tectonic setting and timing of ore genesis.

Geology, C–O–S–Pb isotopes, and their implications for the ore genesis of the Xiaohe carbonate-hosted Zn–Pb deposit in northeastern Yunnan, China

The Xiaohe carbonate-hosted Zn–Pb deposit is located in the southwest Yangtze Block of the Tethyan Metallogenic belt, northeastern Yunnan, China. The accumulated Zn–Pb reserves account for approximately 2.19 million tons, with an average ore grade of Zn and Pb at 10 wt%. Zn–Pb mineralization occurs mainly in dense massive, stockwork, bedded and disseminated forms in the NW- and SN-trending faults and sedimentary dolostone of the Ediacaran Dengying Formation. The sulfide ore and gangue minerals mainly comprise pyrite, sphalerite, galena, and hydrothermal dolomite as well as calcite with a granular, filled, zonal and coedge texture. In order to reveal the nature and origin of ore-forming fluids and ore genesis of this deposit. In this paper, the large-scale tectonic-altered lithofacies mapping method in different mining levels is adopted, and C–O, S, Pb isotopes of different hydrothemal minerals have been analyzed. The results show that the paragenesis of sulfides, hydrothermal dolomite and quartz were found along NW-trending tenso-shear faults with obvious mineralization and alteration zoning patterns. The hydrothermal period can be subdivided into three stages: 1) dolomite–pyrite–quartz, 2) sphalerite–galena–pyrite and 3) calcite. The results of the C–O–S–Pb isotopic compositions showed that the ore-forming fluids of the deposit had the characteristics of multisource fluids mixing. The δ13CPDB and δ18OSMOW values of the carbonate rocks ranged from −4.4‰ to +0.9‰ and +16.6‰ to +24.5‰, respectively, suggesting that the carbon in the ore-forming fluids mainly originated from the dissolution of marine carbonates of the Ediacaran Dengying Formation and mixing with basement-source carbon. The δ34S values of sulfides from different stages ranged from +14.3‰ to +29.1‰, indicating a reduction in sulfur that was derived from marine sulfates of the host rocks by thermochemical sulfate reduction. Different sulfides had scattered Pb isotope compositions, and the data cluster resembled that of basement rocks (Kunyang and Huili groups). Moreover, some of the values were similar to those of the Ediacaran to Triassic carbonate rocks, indicating that the ore-forming metals had mixed sources but were mainly from basement rocks. Considering the above results, this work concluded that the genesis of the Xiaohe Zn–Pb deposit is a Huize-style (also be called as Mississippi Valley type-like) Zn–Pb deposit hosted by carbonate rocks and controlled by tenso-shear faults.

Sulfide-associated hydrothermal dolomite and calcite reveal a shallow burial depth for Alpine-type Zn-(Pb) deposits

Abstract Difficulties in dating Mississippi Valley–type (MVT) mineral deposits and the often closely associated dolomitization have led to controversy regarding their origin. We report the first radiometric ages for the Gorno mining district in northern Italy, an example of the Alpine subclass of MVT deposits. U-Pb ages of hydrothermal carbonates pre- and postdating the ore-forming event show that base-metal mineralization occurred shortly after the deposition of the Carnian host rocks. This implies that the Gorno ore deposits formed at shallow burial depth prior to the Early Jurassic western Tethys rifting phase. Contemporaneous Triassic magmatism and extensional tectonics likely contributed to the high geothermal heat fluxes required to drive the mineralizing system. Our study reinforces the need for reliable geochronological data for metallogenic models and warns against a general application of classic North American MVT models to similar deposits worldwide.

Metals in Plant Functional Types of Ombrotrophic Peatlands in the Sudetes (SW Poland).

The Sudetes are remarkable for the variety and number of peat bogs which receive nutrients via precipitation from atmospheric deposition as the only source of minerals. As this type of peat bogs with a very low buffering capacity is affected in the Sudetes by long-range exhausts from the former Black Triangle, strong response to atmospheric contamination may be expected. Therefore these peat bogs are highly suitable for bioindication purposes. As a result, metal levels in peat and plants should be controlled to evaluate potential ecological damage and to devise treatment strategies. The aim of this study was to evaluate the concentration of Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn in species from different plant functional types (PFTs): shrubs, evergreen dwarf shrubs, deciduous dwarf shrubs, tussock sedges, non-tussock sedges, forbs, Sphagnum mosses, brown mosses, liverworts, and algae collected from peat bogs of the Izera, Karkonosze, and Bystrzyckie Mountains. PFTs of the Karkonosze peat bogs situated above the upper forest line contained higher metal concentrations than those of the Izera and Bystrzyckie peat bogs from lower altitudes and surrounded by forests. Of all PFTs, the algae Zygogonium ericetorum accumulated the highest levels of Fe, Pb, and Zn. The PFTs of Sphagnum mosses were also very effective bioindicators of Cd, Cr, Fe, Hg, and Pb deposition to peat bog ecosystems. Pb, Fe, and Cr found in the examined vascular PFTs originated from atmospheric deposition. The results showed that airborne contaminants, including the ones connected with long-range transport, can make a significant contribution to a load of trace metals in peat bogs located above the upper forest line. These airborne depositions facilitate better recognition of the transport of contaminants carried over great distances and should be taken into account in monitoring and environmental protection programs. In particular, the results, first of all, show the differences in the bioaccumulation of metals in PFTs and their response to trace metal levels in such habitats. Of all PFTs, algae and Sphagnum mosses were the best choices for bioindication of trace metal pollution in ombrotrophic mountain mires. PFTs have not been used so far for investigating ombrotrophic mountain mires in Europe. Thus results of this investigation could be extended to this type of peat bogs in the mountains of Central Europe for better selection of PFTs for bioindication purposes.