Sb Deposition Research Articles

Nucleation, growth and dissolution behaviour of galvanostatically deposited Sb/Sb-oxide on carbon steel

Effective removal of radioactive Sb is a major concern during decontamination of structural materials in nuclear reactors. Galvanostatic deposition under different pH conditions was used to simulate Sb deposit on carbon steel. The difference in nucleation, growth and type of Sb species on carbon steel under different deposition conditions were studied by morphological, structural, compositional and electrochemical characterizations. Electrochemical nucleation over-potential and pH at the electrode interface were found to play dominant roles in deciding the growth pattern and the type of deposition. At low pH, elemental Sb was dominant, whereas the oxide form dominated at higher pH. Open circuit potential measurements and dissolution experiments on the deposits formed with complexing agents used in decontamination showed a difference in surface modification. This results in, incomplete removal of Sb from carbon steel surface, revealing the inadequacy in Sb decontamination using only chelants and the need for employing oxidizing agents in tandem.

Mineralization timing and genesis of the Qukulekedong Au–Sb deposit in the East Kunlun Orogenic Belt, northern tibetan Plateau: Constraints from arsenopyrite Re–Os ages, zircon U–Pb ages, and Lu–Hf isotopes

The Qukulekedong Au–Sb deposit is the first large Au–Sb deposit discovered in the western section of the East Kunlun Orogenic Belt. Even though the significance of the deposit is important, mineralization timing and genesis of the deposit have remained elusive. This study integrated a regional geological survey and the analysis of deposit characteristics with newly acquired geochemical data (Re–Os dating, LA–ICP–MS zircon U–Pb dating, and Lu–Hf isotopes) to gain insights into the chronology and genesis of this deposit. The deposit is closely related to granodiorite and diorite porphyry intrusions in space. The orebody occurs in the inner and outer contact zones of the intrusions and is characterized by disseminated, quartz veins, and breccia type mineralization. The main Au-bearing minerals are pyrite, arsenopyrite, and stibnite. The zircon U–Pb ages of the granodiorite and diorite porphyry are 214.8 ± 1.1 Ma and 211.0 ± 3.7 Ma, respectively. The Re–Os isochron age of Au-bearing arsenopyrite is 209 ± 12 Ma. The εHf(t) values of zircons from the granodiorite range from 4.78 to 9.16, the εHf(t) of zircons from the diorite porphyry range from −1.81 to 7.05, and the initial 187Os/188Os value of Au-bearing arsenopyrite is 0.7851 ± 0.0079, indicating that the magmas of deposit were derived from the lower crust and ore-forming materials were mainly derived from ancient lower crust. These results show that the Qukulekedong Au–Sb deposit was formed in a Late Triassic post-collision extensional background and is an Au–Sb deposit related to the crust-derived magmatic activity. There is still significant prospecting potential in the depth of the deposit.

Hydrous ferric oxides (HFO's) precipitated from contaminated waters at several abandoned Sb deposits – Interdisciplinary assessment

The presented paper represents a comprehensive analysis of ochre sediments precipitated from Fe rich drainage waters contaminated by arsenic and antimony. Ochre samples from three abandoned Sb deposits were collected in three different seasons and were characterized from the mineralogical, geochemical, and microbiological point of view. They were formed mainly by poorly crystallized 2-line ferrihydrite, with the content of arsenic in samples ranging from 7 g·kg−1 to 130 g·kg−1 and content of antimony ranging from 0.25 g·kg−1 up to 12 g·kg−1. Next-generation sequencing approach with 16S RNA, 18S RNA and ITS markers was used to characterize bacterial, fungal, algal, metazoal and protozoal communities occurring in the HFOs. In the 16S RNA, the analysis dominated bacteria (96.2%) were mainly Proteobacteria (68.8%) and Bacteroidetes (10.2%) and to less extent also Acidobacteria, Actinobacteria, Cyanobacteria, Firmicutes, Nitrosprae and Chloroflexi. Alpha and beta diversity analysis revealed that the bacterial communities of individual sites do not differ significantly, and only subtle seasonal changes were observed. In this As and Sb rich, circumneutral microenvironment, rich in iron, sulfates and carbonates, methylotrophic bacteria (Methylobacter, Methylotenera), metal/reducing bacteria (Geobacter, Rhodoferax), metal-oxidizing and denitrifying bacteria (Gallionella, Azospira, Sphingopyxis, Leptothrix and Dechloromonas), sulfur-oxidizing bacteria (Sulfuricurvum, Desulphobulbaceae) and nitrifying bacteria (Nitrospira, Nitrosospira) accounted for the most dominant ecological groups and their impact over Fe, As, Sb, sulfur and nitrogen geocycles is discussed. This study provides evidence of diverse microbial communities that exist in drainage waters and are highly important in the process of mobilization or immobilization of the potentially toxic elements.

Non-diaphragm electrodeposition of antimony: Effect of process parameters and precipitating agents

Metallic antimony production from antimony-bearing materials is a research hotspot. The conventional electrowinning technology of antimony is a challenging problem due to the sulfur compounds that come from both the ore itself and the leaching solution in the electrolysis system. The electro-production of antimony in modified non-diaphragm cells is of interest because of the high price and maintenance issues associated with diaphragm cells. A sulfur-based problem in non-diaphragm cells was the focus of this study, which investigated the effects of various salts on this problem and also optimized antimony production conditions. Various salts (i.e., BaCl2, CaCl2, Ba(OH)2, Ca(OH)2) were used as a precipitating agent for the formation of insoluble salts (BaSO4/CaSO4 and BaSO3/CaSO3). Sb concentration, amount of NaOH and Na2S in the bath, electrowinning time, and temperature were investigated to optimize reaction parameters. The Taguchi experimental design was used to determine the effect of each factor on the Sb deposition. The phases and structures formed during electroproduction were identified with the help of various measurement techniques. This study found that in the presence of 96 mM BaCl2, 45 g/L of Sb concentration, 100 g/L of NaOH, and 60 g/L of Na2S were the most suitable factors. It was found that 40 oC was the optimal electrowinning temperature. This result also demonstrated that increasing concentrations of BaCl2 reduced specific energy consumption.

Chemical insight into the hydrothermal deposition of Sb2(S,Se)3 towards delicate microstructure engineering

The deposition and annealing of hydrothermally deposited Sb2(S,Se)3 are driven by Sb2(Sx,Sey)3 and Sb2(S,Se)3 amorphous nanocrystals, and a zeolite additive can significantly improve the microstructural performance of the Sb2(S,Se)3 absorber layer.

Ex-Situ N-Type Heavy Doping of Ge1-Xsnx Epilayers by Surface Sb Deposition and Pulsed Laser Melting

Ex-Situ N-Type Heavy Doping of Ge1-Xsnx Epilayers by Surface Sb Deposition and Pulsed Laser Melting

Infrared thermographic investigation of the oxidation behaviour of sulfide minerals from antimony-bearing rocks exemplified by the Podkozara deposit, Bosnia-Herzegovina

To date, prediction of the drainage chemistry of geologic materials at mine sites commonly relies upon well-established mineralogical and geochemical test work. Antimony (Sb) deposits require water quality risk assessments that consider the contaminant's solubility and mobility behaviour. To investigate the oxidation reaction of sulfides, a newly designed infrared (IR) thermographic test protocol was used to visualise oxidising sulfide minerals and to classify the rock types from the Podkozara Sb project, Bosnia-Herzegovina according to their oxidation reactivity. Furthermore, the sample materials were geochemically and mineralogically analysed using pXRF, powder XRD, ICP-AES, ICP-MS and NAGpH techniques. Four rock types have been recognised in the deposit: (i) stibnite mineralised quartz veins (SMQV); (ii) stibnite mineralised carbonate rocks (SMCR); (iii) pyritic phyllites; and (iv) mylonitic marbles. As indicated by the defined rock types, stibnite and pyrite are the only two sulfide minerals detected in the sample materials, causing reactions of varying intensities during IR testing. The intensity and duration of the oxidation reaction depends on various factors, including the sulfide mineral itself, the ore content and galvanic reactions between the sulfide minerals. Based on IR testing, it could be demonstrated that SMQV and SMCR are highly reactive and have a high risk for sulfide oxidation and associated Sb release into waters in any pH environment. Pyritic phyllites and tailings show less oxidation reaction intensities and no oxidation reactions could be recorded for marbles. Tailings pose a low risk and pyritic phyllites as well as marbles do not show a risk at all for Sb deportment. For pyritic phyllites, however, a release of Fe must be considered. In addition, underground mine and local surface waters were analysed for their pH, Eh as well as dissolved metal, metalloid and sulfate contents. The mine waters possess especially strongly elevated Sb values (5–244 μg/L) at neutral to alkaline pH values (7.0–8.1). Thus, in the Podkozara deposit, there is a general excess of neutralising carbonate minerals that result in adequate buffering of generated sulfuric acid, limiting mobility of base metal cations in solution but this supports the mobilisation of Sb into mine waters. In this study, complementary conventional mineralogical and geochemical testing as well as novel IR visualisation of possible sulfide oxidation have revealed useful information on the likelihood of different rock types causing metalliferous drainage issues. In particular, IR thermographic testing provides valuable insights on the presence of oxidising Sb- and Fe-sulfides in ores and wastes. This information can be used to prepare suitable mitigation strategies for Sb-rich neutral mine drainage waters and serves as a sample pre-selection for long-term environmental studies and tests. Furthermore, this analysis shows that different management and separate disposal plans will be needed for different lithological wastes.

Mercury isotope constraints on the genesis of late Mesozoic Sb deposits in South China

Mercury isotope constraints on the genesis of late Mesozoic Sb deposits in South China

Accumulation, regional distribution, and environmental effects of Sb in the largest Hg–Sb mine area in Qinling Orogen, China

In this study, knowledge gaps on Sb concentration in rocks, ores, tailings, soil, river water, sediments, and crops of mine areas were identified and discussed in terms of contamination levels, spatial distribution, and environmental effects. Accordingly, Xunyang Hg–Sb mine, the largest Hg–Sb deposit in China as research region in this study, field sampling and laboratory analysis were conducted. The results showed elevated concentrations of Sb in the soil, sediment, and river water. The X-ray diffraction analysis indicated that the main minerals of the rocks were quartz, dolomite, calcite, and margarite. Based on the TESCAN integrated mineral analyzer analysis, the main ore minerals in the Gongguan mine were dolomite (93.97%), cinnabar (2.50%), stibnite (2.48%), calcite (0.38%), and quartz (0.38%). The μ-XRF analysis indicated that Sb distribution was similar to those of S and O, instead of those of Hg and As. The clear spatial variation of Sb concentration in environmental media, mines, tailings, and settling ponds affected Sb accumulation. Actinobacteriota, Proteobacteria, Acidobacteriota, and Chloroflexi were the dominant phyla in the soil. Patescibacteria, Proteobacteria, and Bdellovibrionota were negatively correlated with Sb in the soil (p < 0.05). Exposure to Sb through maize grain and cabbage consumption poses serious non-carcinogenic health risk for residents. This work provides a scientific basis for the environmental quality assessment of Sb mine areas and development of applicable guidelines.

Implications of Soil Potentially Toxic Elements Contamination, Distribution and Health Risk at Hunan’s Xikuangshan Mine

A field survey was conducted to determine the pollution grade, sources, potential ecological risk, and health risk of soil potentially toxic elements (PTEs) in Xikuangshan Mine (XKS), the largest antimony (Sb) deposit in the world. A total of 106 topsoil samples were collected from 6 sites in XKS to measure the concentrations of PTEs Cr, Zn, Cd, Pb, As, Hg, and Sb. The results show that the average concentrations of these elements at all six sites were generally greater than their corresponding background values in Hunan province, especially Sb, Hg, and As. Correlation and principal component analyses suggested that Cd, Zn, Pb, Hg, and Sb were primarily released from mining and other industrial and human activities, while Cr and As were mainly impacted by the parent material from pedogenesis. A risk index analysis showed that, overall, sites were at very high ecological risk, and Sb is the highest ecological risk factor, followed by Cd and Hg. According to health risk assessment, oral ingestion is the main non-carcinogenic and carcinogenic risk exposure route. The higher potentially non-carcinogenic and carcinogenic risks happen to the local children who live in the vicinity of mining area. It revealed that the mining and smelting processes of XKS have negatively influenced the local people, therefore, we should pay increasing attention to this practical issue and take effective measures to protect the ecology of XKS.

Pattern formation during Sb/Sb2O3 electrodeposition

Sb/Sb2O3 composites are considered promising materials for numerous applications, such as secondary batteries, catalysis and thermoelectrics. Recent research shows that nanostructured Sb/Sb2O3 micro-composites can be obtained straightforward by a single-step electrochemical deposition process. While macroscopically homogenous deposits are obtained in most cases it is shown herein that pattern with Sb and Sb2O3 rich regions emerge under specific conditions. The pattern formation is investigated using electrochemical methods combined with in-situ optical observation and electron microscopy. The origin of pattern formation is proposed to be related to the complex interactions between electrochemical Sb deposition and chemical Sb2O3 precipitation in combination with the emergence of convection patterns in the vicinity of the electrode. These findings contribute to a fundamental understanding in the nascent field of electrochemical metal/oxide co-deposition and can be useful for the rational design of advanced functional composite coatings.

Antimony isotope fractionation in hydrothermal systems

In order to characterize antimony (Sb) isotope fractionation in hydrothermal systems, we present Sb isotope compositions of primary stibnite ores from a large Sb deposit in south China. A total number of 39 analyses reveals a large δ123Sb range of −0.27 to +0.86‰, representing an up to 1.13‰ variation in this hydrothermal system. A gradual increase of Sb isotope ratios from the proximal to the distal parts was observed in stibnite ores. Rayleigh distillation models the systematic variation trend of the Sb isotope values, demonstrating that ore fluids are preferentially enriched in heavier Sb isotopes during the precipitation of isotopically light stibnite. In this way, we consider that separation of stibnite from a Sb-bearing fluid related to reaction kinetics as a cause for Sb isotope fractionation. The modeled data constrain a Sb isotope fractionation factor (αfluid-stibnite) between hydrothermal fluid and stibnite at approximately 0.9994. The model also constrains an initial Sb isotope value of ~0.45‰, which indicates metal sources in the basement rocks of the study area. Given that distal stibnites possess higher Sb isotopic values, Sb isotopes could be used to fingerprint hydrothermal fluid flow and unravel different processes in natural systems.

Source characteristics and genesis of Sb mineralization from the Au and Sb deposits of the Youjiang Basin, SW China: constraints from stibnite trace element and isotope geochemistry

Source characteristics and genesis of Sb mineralization from the Au and Sb deposits of the Youjiang Basin, SW China: constraints from stibnite trace element and isotope geochemistry

Sm–Nd Isochron Age Constraints of Au and Sb Mineralization in Southwestern Guizhou Province, China

Southwestern Guizhou, China, is famous for hosting clusters of Carlin-type Au, Sb, and Hg-Tl deposits. These deposits are thought to be the products of a low-temperature hydrothermal metallogenic event. Calcite and fluorite are common and widespread gangue minerals in Au and Sb deposits, respectively. Ore-related calcite commonly coexists with stibnite, realgar, and orpiment at the periphery of high-grade orebodies in Au deposits, while ore-related fluorite is generally intergrown with stibnite in Sb deposits. In this study, ore-related calcite and fluorite samples from representative Au (Zimudang) and Sb (Dachang) deposits, respectively, were separated, and the rare earth element (REE) concentrations, Sm/Nd isotope ratios, and Sm–Nd isochron ages were analyzed. This study aims to determine the formation ages of the calcite and fluorite and to constrain the age of low-temperature metallogenic event in Southwestern Guizhou. The calcite and fluorite samples contain relatively high total concentrations of REEs (8.21–22.5 μg/g for calcite, 21.7–36.6 μg/g for fluorite), exhibit variable Sm/Nd ratios (0.51–1.01 for calcite, 0.35–0.49 for fluorite), and yield Sm–Nd isochron ages of 148.4 ± 4.8 and 141 ± 20 Ma, respectively. These ages are consistent with the age range constrained by the low-temperature thermochronology of zircon (132–160 Ma), crosscutting relationships of stratigraphy or intrusions (96–160 Ma), and previous dating results (135–150 Ma) in Southwestern Guizhou. Collectively, the ages obtained in this study add new evidence to previous geochronology studies, such that the low-temperature hydrothermal mineralization in Southwestern Guizhou can be constrained to 135–150 Ma, corresponding to the Yanshanian orogeny, which was associated with a weak extensional tectonic environment.

Characterizing armchaired and zigzagged phases: Antimony on oxide layer of Cu(110)

Antimony nanostructures fabricated on metal oxide layers are essential for practical applications in fields of solar cells, electronic and photonic devices. Here the antimony phases were systemically studied on the copper oxide of Cu(110). By high-resolution scanning tunneling microscopy (STM), we revealed that a wrinkled antimony phase was formed on the CuO surface regardless of the initial oxide structure. It exhibited an armchair-like configuration making up of protruded and dipped Sb atoms as confirmed by STM and density functional theory calculations. Further Sb deposition caused the armchair-like phase distorting and subsequently gave rise to formation of a c(2 × 2)-Sb phase. Finally, another kind of wrinkled phase was successfully fabricated. It consisted of two zigzagged antimony chains with protruded and dipped Sb atoms alternately distributing. By analysis of the atomically-resolved STM topographies, several kinds of dislocations have been observed and the corresponding geometric models are addressed. The armchair and zigzag phases both exhibited high stabilities for oxygen exposure. Conductance measurements imply that each phase interacts with the underlying layer. Our results might provide a way for fabricating stable ultrathin materials with a well-defined edge structure on oxide surfaces.

Antimony in quartz as a vector to mineralization: A statistical approach from five Variscan Sb occurrences (France)

Using in-situ LA-ICP-MS, the trace-element composition of hydrothermal quartz from five Sb mineralized Variscan districts, from different parts of France, were compared. Each of these districts is characterized by the presence of stibnite, with quartz being a ubiquitous gangue mineral. The resulting dataset was processed using a set of multivariate statistical analyses (i.e. principal component analysis, hierarchical cluster analysis, and permutational multivariate analysis of variance). This approach highlights differences in ore-forming processes (e.g., fluid chemistry), recorded in the trace-element pattern of gangue minerals. Using this methodology, we could distinguish different mineralizing events with intricate paragenesis, such as those in the Sioule nappe, which appear to have recorded two different events of Sb precipitation. Results indicate that Sb incorporation in quartz is weakly correlated to other trace elements, but that its contents increase sharply in quartz from stibnite-bearing veins. In this case, Sb shows values >10 ppm and up to 200 ppm, considerably higher than the values measured in quartz unrelated to Sb mineralization (mainly ≤1 ppm). Intermediate Sb contents in quartz would point to the potential for a fluid to precipitate Sb ore. It is concluded that incorporation of Sb in quartz can be confidentially correlated to its content in the mineralizing fluid. Based on our data from five Sb districts in the French Variscan belt, supplemented by published Sb trace-element data in quartz from a number of other Sb deposits around the world, this study highlights the strong potential of the Sb content of quartz as a proxy for tracing Sb mineralization.

Deposition of Sb2Se3 thin films on Pt substrate via electro-chemical atomic layer epitaxy (EC-ALE)

Abstract This work deals with the deposition of a Sb2Se3 thin film on a Pt substrate using Electro-Chemical Atomic Layer Epitaxy (EC-ALE). We first investigated the UPD of selenium on a Pt substrate. Two routes have been evidenced to get a UPD layer of Se, either the polarization of the Pt-substrate at around 0.35 V in the Se solution or the deposition of full UPD Se together with bulk deposition of Se and dissolution of the latter one at lower potentials. The following investigation on the electrochemical behavior of antimony on selenium-covered platinum electrode by cyclic voltammetry and anodic potentiodynamic studies led us to choose the two-steps procedure for the Se deposition. After an optimization of the deposition parameters, the alternate deposition of Sb and Se elements to form the Sb2Se3 compound by EC-ALE on platinum substrate has been performed. The stoichiometry of the deposited film has been evaluated by coulometry and it has been confirmed by atomic force microscopy (AFM).

Gold and antimony metallogenic relations and ore-forming process of Qinglong Sb(Au) deposit in Youjiang basin, SW China: Sulfide trace elements and sulfur isotopes

In the northwestern margin of the Youjiang basin (NWYB) in SW China, many Carlin-like gold deposits are highly antimony (Sb)-rich, and many vein-type Sb deposits contain much Au. These deposits have similar ages, host rocks, ore-forming temperatures, ore-related alterations and ore mineral assemblages, but the Au and Sb metallogenic relations and their ore-forming process remain enigmatic. Here we investigate the large Qinglong Sb deposit in the NWYB, which has extensive sub-economic Au mineralization, and present a new metallogenic model based on in-situ trace elements (EPMA and LA-ICP-MS) and sulfur isotopes (NanoSIMS and fs-LA-MC-ICP-MS) of the ore sulfides. At Qinglong, economic Sb ores contain coarse-grained stibnite, jasperoid quartz and fluorite, whilst the sub-economic Au–Sb ores comprise dominantly veined quartz, arsenian pyrite and fine-grained stibnite. Three generations of ore-related pyrite (Py1, Py2 and Py3) and two generations of stibnite (Stb1 and Stb2) are identified based on their texture, chemistry, and sulfur isotopes. The pre-ore Py1 is characterized by the lower ore element (Au, As, Sb, Cu and Ag) contents (mostly below the LA-ICP-MS detection limit) and Co/Ni ratios (average 0.31) than the ore-stage pyrites (Py2 and Py3), implying a sedimentary/diagenetic origin. The Py2 and Py3 have elevated ore element abundance (maximum As ​= ​6500 ​ppm, Au ​= ​22 ​ppm, Sb ​= ​6300 ​ppm, Cu ​= ​951 ​ppm, Ag ​= ​77 ​ppm) and Co/Ni ratios (average 1.84), and have positive As vs. Au–Sb–Cu–Ag correlations. Early-ore Stb1 has lower As (0.12–0.30 ​wt.%) than late-ore Stb2 (0.91–1.20 ​wt.%). These features show that the progressive As enrichment in ore sulfides is accompanied by increasing Au, Sb, Cu and Ag with the hydrothermal evolution, thereby making As a good proxy for Au. As-rich, As-poor and As-free zones are identified via NanoSIMS mapping of the Au-bearing pyrite. The As-rich zones in the Qinglong Au-bearing pyrites (Py2 and Py3) and ore stibnites (Stb1 and Stb2) have narrow δ34SH2S ranges (−8.9‰ to +4.1‰, average −3.1‰) and −2.9‰ to +6.9‰, average ​+ ​1.3‰), respectively, indicating that the Au-rich and Sb-rich fluids may have had the same sulfur source. Published in-situ sulfur isotopic data of pyrite As-rich zones from other Carlin-like Au deposits (Shuiyindong, Taipingdong, Nayang, Getang and Lianhuashan) in the NWYB have similar ore-fluid δSH2S34 values (−4.5‰ to +6.7‰, average −0.6‰) to those of Qinglong. Therefore, we infer that the sulfur of both Au and Sb mineralization was derived from the same magmatic-related source (0 ​± ​5‰) in the NWYB.Moreover, the core of pyrites (Py1) has variable S isotope fractionation (−18.9‰ to +18.1‰, mostly +3‰ to +12‰), suggesting that the higher-34S H2S was produced by bacterial sulfate reduction (BSR). The hydrothermal pyrite (Py2 and Py3) δ34S values gradually decrease with increasing As concentrations, and ultimately, within the restricted range (−5‰ to +5‰) in As-rich zones. This variation implies that the As-rich pyrite was formed through ongoing interactions of the magmatic-hydrothermal fluid with pre-existing sedimentary pyrites, causing the progressive decreasing δ34S values with As content increase, Hence, the fluid/mineral interaction may have generated the observed variation in δ34S and As contents. Overall, comparing the Au and Sb deposits in the NWYB, we favor a magmatic-related source for the Au–Sb–As-rich fluids, but the Au- and Sb-ore fluids were likely evolved at separate stages in the ore-forming system.

In situ U-Pb Dating of Calcite from the South China Antimony Metallogenic Belt.

SummaryAccurately determining the age of hydrothermal ore deposits is difficult, because of lack of suitable mineral chronometers and techniques. Here we present the first LA-MC-ICPMS U-Pb age of carbonates from hydrothermal Sb deposits. Three stages of hydrothermal carbonates from the giant South China Sb metallogenic belt were identified: (1) pre-ore dolomite (Dol-I), (2) syn-ore calcite (Cal-II), and (3) post-ore calcite (Cal-III). The U and Pb isotopic data show that Cal-II yielded a lower intercept age of 115.3 ± 1.5 Ma (MSWD = 2.0), suggesting a Sb mineralization that corresponds to an extension event occurred during the early Cretaceous in South China. Although Cal-III yielded an age of 60.0 ± 0.9 Ma (MSWD = 1.5), indicating a potential tectonothermal event occurred in this belt during the early Cenozoic. Hence, in situ U-Pb dating of calcite offers a new way to determine the age of hydrothermal ore deposits.

Fluid inclusion, H–O–S isotope and rare earth element constraints on the mineralization of the Dong’an Sb deposit, South China

Systematic geochemical study on the Cambrian strata-hosted Dong’an Sb deposit in the Central Hunan Sb belt would provide key information on the origin of the low-temperature mineralization in South China. In this study, microthermometric, H–O isotopic and fluid composition analyses on ore-bearing quartz, S isotopic analyses on sulfides, and rare earth element (REE) analyses on wall-rocks and monominerals (stibnite, pyrite and quartz) in ores were conducted to constrain the genesis of the Dong’an Sb deposit. Two major stages of mineralization were identified in the Dong’an deposit: (1) an early pyrite-stibnite-quartz stage mineralization with intense wall-rock alteration occurring at depth of the deposit, and (2) a late quartz-stibnite stage mineralization occurring at shallow depths. Microthermometric analyses reveal a low temperature (150 to 230 °C), low salinity (4.5–7.0 wt% NaCl equiv.), low density (0.88–0.96 g/cm3), low pressure (4.5 MPa) and weakly acid (pH = 5.74) fluid for the Sb mineralization. Compositional analyses for fluid inclusions show that the main ion compositions are Na+, K+, Mg2+, Ca2+, F−, Cl− and SO42−, while the gas compositions are dominated by H2O and CO2. This suggests that the ore-forming fluids were enriched in alkali metals, sulfur and halogen. The H–O isotopic compositions (δ18OH2O = 2.52‰ to 7.13‰, δ2HH2O = −88.6‰ to −58.3‰) of fluid inclusions in quartz suggest a mixture of magmatic water, metamorphic rocks-derived brine and meteoric water. The δ34S values of stibnite (−1.32‰ to +2.86‰) and pyrite (+17.4‰ to +23.6‰) are very different, suggesting multi-sulfur sources involving buried magmatic rocks, ore-bearing meta-sedimentary rocks and deep basement rocks. The decreasing of REE contents from early to late mineralization stages reflects a decrease of temperature, reduction of fluid-rock interaction and input of meteoric water along with the stibnite precipitation. We propose that Precambrian strata that underwent regional metamorphism during Early Paleozoic acted as a Sb source bed, whereas strong tectono-magmatism in the early Mesozoic provided thermal driving force for the Sb mineralization occurring under a tensile stress in secondary faults at the shallow crust. This study highlights the use of multi-geochemical methods to constrain the genesis of large-scale Sb mineralization in South China.