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The Baiyun gold deposit is a medium-sized deposit in northeastern Hubei around the southern margin of the Tongbai-Dabie metallogenic belt. However, its genesis has not been determined. The metallogenic process of the Baiyun gold deposit can be divided into three stages: quartz + feldspar, quartz + native gold + electrum + polymetallic sulfides, and quartz + pyrite + calcite + iron dolomite + illite. In this study, LA-ICP-MS was used for in situ trace element and isotope analyses in the main and late ore stage hydrothermal sulfides to evaluate the genesis and evolution of ore-forming fluids. Gold is positively correlated with Ag, Cu, Pb, Zn, and Te and the Co/Ni ratio is greater than 1. The S isotope values of Py1 and Py2 are −0.23–3.04‰ and 1.27–6.09‰, respectively. As mineralization progressed, S isotope values increased. In situ S isotope values of the two types of galena symbiotic with pyrite in the main metallogenic stage are 2.97–3.47‰. In situ Fe isotopic values of pyrite are −0.05–0.82‰; values in the two stages are similar without significant fractionation. We inferred that the Baiyun gold deposit formed via magmatic mineralization related to the subduction of the Pacific Plate during the Yanshanian. [ABSTRACT FROM AUTHOR]

Concentrically zoned pyrite aggregates (CZPA) are common in sediment‐hosted massive sulfide (SHMS) deposits and have been widely used to interpret the ore‐forming processes. There is considerable uncertainty, however, over the formation of aggregates that are oscillatorily zoned and contain randomly‐orientated pyrite microcrystals. Guided by the results of examination of the micro‐textures of CZPA and in‐situ chemical analyses, we conducted a quantitative diffusion‐reaction simulation to assess the mechanism of CZPA formation. Our study shows that oscillatory zoning results from the feedback between the diffusion of reactants and the nucleation‐growth of Fe‐sulfides. Externally derived Fe2+ diffuses into the early diagenetic sediments containing decomposing organic matter (2CH2O + SO42− = 2HCO3− + H2S) and reacts with H2S to form a pyrite layer via an intermediate pathway (Fe2+ + H2S → FeS + 2H+, FeS + H2S → FeS2 + H2). This growth of pyrite layers depletes the local concentration of reactants and suppresses nucleation until the diffusive reaction front advances and another layer is formed. Intermediate phases, for example, mackinawite, nucleate instead of pyrite, because of their greater ease of nucleation due to the low surface tension, and lead to the domination of nucleation over growth. The nucleation of mackinawite and occurrence of siderite in the CZPA are consistent with a low temperature, high pH, anoxic early diagenetic environment. Our study demonstrates that CZPA in SHMS deposits are formed by intrinsic self‐organizational processes rather than by extrinsic changes of ore‐forming fluids. The CZPA in SHMS deposits are thus indicative of their diagenetic origin with Fe2+ infiltrated and diffused from hydrothermal fluids into the sediments. Plain Language Summary: Oscillatory zoning patterns are a phenomenon commonly encountered in scientific disciplines that include biology, geology, chemistry and atmospheric physics. To decipher these patterns, we employ a unifying principle that leverages a reaction‐diffusion approach and successfully replicate the textures observed in a massive sulfide deposit, via numerical simulations. In addition, we show that factors such as the concentration, distribution, and mobility of reactant species, such as the iron ion, sulfide, and organic matter in sediments, influence the texture of patterns at both the millimeter and nanometer scales. Our proposed numerical models yield results that closely align with the oscillatory zoning patterns observed in pyrite‐siderite from the Xinqiao massive sulfide deposit in Central China. The broader impact of this work lies in the development of a computer simulation‐based protocol, which sheds light on the processes forming massive sulfide deposits. This, in turn, has the potential to significantly aid the exploration for new metal and sulfide resources beneath the surface of the Earth. Key Points: Reactive‐diffusion simulations of the formation of concentrically zoned pyrite aggregates in sediment‐hosted massive sulfide depositsThe ore textures were the result of an intrinsic self‐organized process rather than extrinsic changes of chemical compositionsProtocols for deciphering diagenetic environments affected by the infiltration of Fe2+‐rich hydrothermal fluids [ABSTRACT FROM AUTHOR]

Global volcanic and plutonic olivines record the compositional characteristics and physicochemical conditions of the parental magmas. Thus, they have significant potential for use as petrogenetic discriminators of the olivine formation environment and prospecting indicators for potential host rocks of magmatic sulfide deposits. Several data visualization approaches have been proposed by researchers to determine olivine origins. However, they can only discriminate specific olivine populations and require the incorporation of trace elements for which data are lacking globally. In this study, a machine-learning method consisting of the random forest algorithm and the synthetic minority oversampling technique (SMOTE) is used to discriminate the crystallization environments of olivine and predict the sulfide potential of olivine-bearing mafic-ultramafic intrusions. We employ a global data set of 24 341 olivine samples from 12 environments to determine the contents of MgO, FeO, Ni, Ca, Mn, and Cr and the Fo number [100 × Mg/(Mg+Fe)]. The results indicate that the proposed method can classify olivine into genetically distinct populations and distinguish olivine derived from mineralized intrusions from that derived from sulfide-barren intrusions with high accuracies (higher than 99% on average). We develop a dimensionality reduction algorithm to visualize the olivine classifications using low-dimensional vectors and an olivine classifier (accessible at http://101.33.204.62:8080/olivine%5fweb/main.html China University of Geosciences, Beijing). The model is used successfully to identify the contributions of distinct sources to regional magmatism using olivines from the late Permian picrite and basalt along the western margin of the Yangtze block (SW China) and to predict the sulfide potential of the newly discovered Qixin mafic-ultramafic complex in the southern Central Asian Orogenic Belt (NW China). The findings suggest that the proposed approach enables the accurate identification of olivine origins in diferent formation environments and is a reliable indicator suitable for global Ni-Cu-platinum group element (PGE) exploration. [ABSTRACT FROM AUTHOR]

The Caoziwa Pb–Zn deposit is one of the typical vein-type Pb–Zn deposits in the western part of the Tengchong block. Due to limited research, the genesis of these deposits is unknown. In this study, the sulfur isotopic and trace elemental compositions of sulfides from the Caoziwa Pb–Zn deposit were analyzed to trace the sources of ore-forming materials, and to reveal the genetic type of this deposit. The results show that abundant Co, Ni, As, and Se, and less Cu, Zn, Ag, Cd, Sn, Sb, Te, Pb, and Bi could enter pyrite by isomorphic substitution. Elemental Mn, Fe, Cd, Co, and Ni could substitute Zn to enter sphalerite, while the contents of Ag, Sn, and Sb are mainly controlled by the Pb-rich inclusions in sphalerite. Elemental Bi, Sb, Cd, Sn, Ag, and Tl mainly enter the galena grains via an isomorphic substitution mechanism of (Bi, Sb)3+ + (Cd, Sn)2+ + (Ag, Tl)+ ↔ 2Pb2+. Both sulfur isotopic compositions and trace elemental compositions indicate that the ore-forming materials and fluids of the Caoziwa Pb–Zn deposit mainly originate from magmatic hydrothermal fluid related to Paleocene granitic magmatism. Combined with the geological facts that some skarnizations developed in the northern part of the ore field near the Paleocene granite, the Caoziwa Pb–Zn deposit is suggested to be a magmatic hydrothermal vein-type deposit that probably belongs to a distal part of a skarn mineralization system developed by the intrusion of Paleocene granitic magmatism in the western part of the Tengchong block. [ABSTRACT FROM AUTHOR]

The Xitieshan deposit, located in the central segment of the northern margin of the Qaidam Basin, is among the largest massive Pb-Zn sulfide deposits in China. This deposit, along with its ore-bearing rock series known as the Tanjianshan Group, underwent greenschist facies metamorphism due to subsequent orogeny. We investigated the in situ sulfur isotopes of sulfides with different occurrences to define the origin of ore-forming fluids. The δ34S values of sulfides from stratiform ores, massive ores in schist, stockwork ores in marble, schist and discolored altered rocks that constitute a typical double-mineralization structure range from −5.3‰ to +5.6‰ and from −1.7‰ to +32‰, respectively, indicating distinct biological and thermochemical reductions in seawater sulfates. These are similar to the sulfur isotopic characteristics of VSHMS deposits. Pyrite, whose LA-ICP-MS trace element compositions can provide significant information about metallogenic evolution and deposit genesis, is ubiquitous throughout the whole mineralization process. In these stratiform, massive and stockwork ores, three pyrite types were identified: colloform pyrite (Py0), fine-grained anhedral spongy pyrite (Py1) and coarse-grained euhedral pyrite (Py2). The contents of most metallogenic elements, such as Cu, Pb, Zn, Ag, Mo, Mn and Sn, decrease from Py0 to Py2 with the enhancement of metamorphic recrystallization. This suggests that the expelled elements appear as inclusions in primitive pyrite, contributing to the precipitation of new sulfide phases, such as sphalerite and galena. Orogenic metamorphism played an important role in controlling further Pb-Zn enrichment of the Xitieshan deposit. Moreover, there is another mineralization type, primarily occurring as sulfide veins in the undeformed Formation C siltstones of the Tanjianshan Group, which also crosscut early-formed sulfides, showing close-to-zero S isotopic compositions. In this mineralization type, pyrite (Py3) displays high Se/Tl (>10) and Co/Ni (>2.2) ratios, both indicating a minor superimposed post-orogenic magmatic–hydrothermal event. [ABSTRACT FROM AUTHOR]

In this study, mineralogical and elemental geochemical characteristics of massive sulfide samples collected from the Jade hydrothermal field, located in the Izena depression in the central graben of the Okinawa Trough, were analyzed by means of optical microscopy, scanning electron microscopy, and electron probe microanalysis (EPMA). The results show that the mineralization in the Jade hydrothermal field can be divided into Zn-Cu-Pb-rich massive sulfides and Zn-Fe-rich massive sulfides. The former is composed of sphalerite, galena, chalcopyrite, pyrite, and anglesite, which is the product of the low-temperature alteration of galena. The latter is mainly composed of sphalerite, pyrite, marcasite, and traces of galena. Cu and Zn in pyrite may exist in the form of microinclusions, while Ag and Pb may exist in pyrite in the form of fine galena inclusions containing Ag. Fe and Cu may enter sphalerite in the form of ion replacement. Zn may enter chalcopyrite in the form of ion replacement. Consistent with the previous understanding, the metal elements in the hydrothermal liquid system in the Jade hydrothermal field mostly migrated as sulfur complexes, and when the hydrothermal fluid mixes with seawater, the physical and chemical conditions of the fluid change, resulting in sulfide mineral precipitation. However, the chemical structure of chalcopyrite is still controversial, which restricts the understanding of the substitution mechanism of trace elements during chalcopyrite precipitation. [ABSTRACT FROM AUTHOR]

Spinel minerals occur as inclusions in both silicates and sulfides in the Kalatongke magmatic Ni-Cu deposit in NW. China, showing textural and compositional variations. The spinel enclosed in olivine and other silicates (orthopyroxene, clinopyroxene, and hornblende) is predominantly Cr-magnetite with minor Cr-spinel, having wide variations in MgO (0.1–8.0 wt%), Al2O3 (1–25 wt%), Cr2O3 (3–20 wt%), and TiO2 (0.5–6.2 wt%) contents. Such continuous variations suggest that Cr-magnetite in silicates was crystallized from residual melts and experienced extensive reaction with trapped liquid undergoing a typical tholeiitic trend of increasing Fe and Ti concentrations. Crystals of Cr-magnetite enclosed in disseminated sulfides have similar Mg, Al, Cr, Ti, V, Sc, Ga, Mo, Zr, and Nb concentrations to the Cr-magnetite in silicates. Such compositional similarity, which is explained by the simultaneous equilibrium crystallization of Cr-magnetite from the silicate and sulfide melts, shows that the Kalatongke deposit is a typical example of where the same mineral phase is formed from two coexisting immiscible liquids. However, the Cr-magnetite in disseminated sulfide and that in silicates show distinctly different crystal size distribution patterns, illustrating that the chemical equilibrium was attained despite contrasting growth rates. Nevertheless, the Cr-magnetite in disseminated sulfides shows significantly lower Ni, Co, and Zn contents (median value of 845, 22, and 319 ppm) than that in silicates (median value of 1428, 160, and 1039 ppm). This cannot be the result of sulfide fractionation because there is little compositional variation between Cr-magnetite included in pyrrhotite (early crystallized phase) and that immersed in chalcopyrite (late crystallized phase). Such Ni, Co, and Zn depletions, combined with the relatively constrained Fe/Ni, Fe/Co, and Fe/Zn ratios in those Cr-magnetite, are attributed to postcumulus reactions between Cr-magnetite and sulfide melts. The spinel hosted by massive sulfides is magnetite, which has distinctly different compositional variations and crystal size distribution patterns compared with those of the silicate-hosted Cr-magnetite, although the magnetite in massive ore generally has similar contents in some lithophile elements (Zr, Ta, Mo, Sn, Mn) to the silicate-hosted Cr-magnetite. This could be taken as evidence for a mixture of early accumulated sulfide pools with a component of drained sulfide from the cumulates above. This study shows a detailed textural and compositional investigation of spinel is useful to decode the sulfide evolution processes during the formation of magmatic Ni-Cu deposits and highlights that equilibrium crystallization and postcumulus reactions play critical roles in controlling the spinel/magnetite composition. [ABSTRACT FROM AUTHOR]

The carbonate-hosted Pb–Zn deposits in the Sichuan–Yunnan–Guizhou (SYG) triangle region are important Indosinian deposits in South China. The Tianbaoshan deposit is a typical large Pb–Zn deposit in the SYG area and occurs as pipe-like type, hosted by Sinian dolostone. It contains ∼26 Mt Zn–Pb ore (7.76–10.09 % Zn, 1.28–1.50 % Pb and 93.6 g t−1 Ag) and >0.1 Mt Cu ore (2.55 % Cu). In this study, the detailed mineral textures, mineral chemical and sulphur isotopic compositions of the various sulphides have been analysed to constrain the abnormal enrichment mechanism and mineralization relationship. Four mineralization stages have been recognized: Stage 1, minor early pyrite (Py1) with relics and infill of intergranular dolomite or quartz grains; Stage 2, Cu mineralization with coarse-grained, elliptical crystal chalcopyrite (Cp1); (3) Stage 3, Zn mineralization with dark fine-grained sphalerite (Sph1) and light coarse-grained sphalerite (Sph2); and (4) Stage 4, as represented by a quartz–calcite assemblage with galena, minor pyrite (Py2) and chalcopyrite (Cp2). The petrography of the sulphide minerals (Py1, Cp1, Sph1 and Sph2) demonstrates a mutual inclusion relationship. The nature of this relationship from core to rim and their similar sulphur isotope values (5.5–8.3 ‰) indicates a single sulphur source, suggesting that the different mineralization types are the result of different stages of a continuous hydrothermal system. Sphalerite geothermometer study suggests that sphalerite in the Tianbaoshan deposit formed in a low-temperature (<200 °C) hydrothermal system. The low concentrations of Mn and In, low In/Ge ratios and high Fe/Cd ratios in the sphalerite are consistent with those of Mississippi Valley-type (MVT) deposits, but different from those of magmatism-related deposits (e.g. epithermal, skarn and VMS deposits). The positive δ34S values for Py1 (5.1–7.9 ‰), Cp1 (5.1–7.2 ‰), Sph1 (4.7–7.4 ‰), Sph2 (3.9–8.7 ‰), Py2 (4.4–9.3 ‰) and Cp2 (5.0–6.8 ‰) indicate a sulphur source from thermochemical reduction of coeval seawater sulphate. Widely developed dissolved textures (caverns and breccias) with massive sulphide infillings and deformed host rock remnants suggest that replacement of host dolostones by ore fluids was volumetrically significant and the ore formed nearly simultaneously with the cavities. The Tianbaoshan deposit is a typical MVT deposit, which resulted from mixing of a H2S-rich fluid and a metal-rich fluid, with thermochemical sulphate reduction occurring before ore precipitation rather than during ore precipitation. [ABSTRACT FROM AUTHOR]

Nickel contents of olivine have been widely used as petrogenetic indicators and as fertility indicators for magmatic sulfide potential of mafic-ultramafic intrusions, on the assumption that olivines crystallized from magmas that had equilibrated with sulfide liquid should be relatively depleted in Ni compared with a sulfide-free baseline. This has given rise to a large accumulation of data that is brought together here, along with data on volcanic olivines, to critically evaluate the effectiveness of the approach. We identify multiple sources of variance in Ni content of olivine at a given Fo content, including variability in mantle melt composition due to depth, water content (and possibly source), subsequent fractional crystallization with and without sulfide, recharge and magma mixing, batch equilibration between olivine and sulfide at variable silicate-sulfide ratio (R), and olivine/liquid ratio; and subsequent equilibration during trapped liquid crystallization in orthocumulates. Baselines for Ni in olivine in relation to Fo content are somewhat lower in orogenic belt settings relative to intrusions in continental large igneous provinces (LIPs). This is probably related to differences in initial parent magma compositions, with plume magmas generally forming deeper and at higher temperatures. No clear, universal discrimination is evident in Ni in olivine between ore-bearing, weakly mineralized, and barren intrusions, even when tectonic setting is taken into account. However, sulfide-related signals can be identified at the intrusion scale in many cases. Low-R factor and low-tenor sulfides are associated with low-Ni olivines in several examples, and these cases stand out clearly. Anomalously high-Ni olivines are a feature of some mineralized intrusions, in part due to trapped liquid reaction effects. However, in some cases, this mechanism cannot account for the magnitude of enrichment. In these cases, enrichment may be due to re-entrainment of "primitive" Ni-rich sulfide by a more evolved Fe-rich magma, driving the olivine to become Ni-enriched due to Fe-Ni exchange reaction between sulfide and olivine during transport. An extreme case of this process may account for ultra-Ni enriched olivine at Kevitsa (Finland), but more subtle signals elsewhere could be positive indicators. A lack of clear mineralized/barren distinction in specific groups of related intrusions, e.g., the deposits of NW China or the Kotalahti Belt in Finland, may well be due to "false negatives" where undiscovered mineralization exists in specific intrusions or in their feeder systems, or may also be due to a multiplicity of confounding factors. Wide variability of both Fo and Ni between related intrusions at regional scale may be a useful regional prospectivity indicator, more than an intrusion-scale discriminant, and is certainly informative as a petrogenetic indicator. In general, the use of Ni-olivine as a fertility tool is more likely to generate false negatives than false positives, but both are possible, and the technique should be used as part of a broader weight-of-evidence approach. [ABSTRACT FROM AUTHOR]

The effect of enrichment with Nd in sulfides from magmatic Cu-Ni-PGE complexes and sulfide ores from hydrothermal Pb-Zn, Au-Mo, and gold deposits was found and characterized. This paper concerns the report and analysis of isotopic geochemical data on the sulfide ores from the large Paleoproterozoic mafic–ultramafic magmatic Cu-Ni-PGE complexes of Fennoscandia and the literature data on sulfide ores from the Qingchengzi Pb-Zn deposit (northeastern China), Tokuzbay gold deposit (southern Altai, northwestern China), and Dahu Au-Mo deposit (central China). The mineral/rock partition coefficients for Nd and Sm (the DNd/DSm ratio) are defined as a prospective tool for the reconstruction of the sulfide mineral formation and geochemical substantiation of possible sources of ore-forming fluids for deposits of various genetic types. The observed selective Nd accumulation indicates either hydrothermal or metamorphic (metasomatic) impact, which is associated with increased Nd mobility and its migration or diffusion. Due to this process, there is a relative Nd accumulation in comparison with Sm and a consequent increase in the DNd/DSm ratio. At the isotopic system level, this leads to a sufficient decrease in the Sm/Nd ratio for the secondary sulfides of such kind. The revealed effect may serve as an isotopic geochemical marker of recent processes. These processes are quite frequently associated with the most important ore formation stages, which bear the commercially valuable concentrations of ore components. Sulfides from magmatic Cu-Ni-PGE complexes are more characterized by the selective accumulation of Nd in the sequential sulfide mineral formation. For sulfides from hydrothermal deposits, the effect of Nd enrichment is more intense and closely related to ore-forming fluids, under the influence of which sulfide mineralization is formed in multiple stages. The study aims at expanding the knowledge about fractionation and the behavior of lanthanides in ore-forming processes and allows the development of additional criteria for the evaluation of the ore potential of deposits with different geneses, ages, and formation conditions. [ABSTRACT FROM AUTHOR]

The first Sino-German workshop on "Deep-sea mining of massive sulfides: balancing impacts on biodiversity and ecosystem, technological challenges and law of the sea" took place from September 17 to September 23, 2023 in Changsha, Hunan Province, China. Four themes were covered by 20 impulse talks, (1) seabed resources and mineralization systems, marine geology and geochemistry, (2) microbiology and marine ecology, (3) deep-sea mining technology, mineral processing and extractive metallurgy, and (4) law of the sea and international law applicable to the marine environment in Areas Beyond National Jurisdiction, respectively. In round table discussions, the interdisciplinary understanding deepened regarding (i) the distribution of submarine massive sulfides (SMS), their formation mechanisms and the abundance of SMS resources, (ii) the biodiversity linked to SMS and hydrothermal vents and the environmental protection requirements, (iii) the challenges of mining technology and processing of SMS, as well as (iv) the legal framework, the regulatory challenges, the international environmental liability regime and due diligence obligations for commercial seabed mining. The participants covered all four themes and are affiliated with various universities, research institutions, and governmental geoscientific authorities from China (seven) and Germany (six). During the workshop, a number of recommendations to ISA were defined regarding environmental, methodological, technical, and legal issues. [ABSTRACT FROM AUTHOR]

Eastern Tianshan is an important nickel ore belt in China, in which large to middle-sized magmatic Ni–Cu sulfide deposits occur spatially in the eastern part. The Baixintan magmatic Ni–Cu sulfide deposit is an important discovery in the western part of Eastern Tianshan, which provides an ideal target to track the evolution of the magmatic mineralization system in this part. The Baixintan intrusion is composed of the northeastern mafic units and the southwestern mafic–ultramafic units. The olivine Fo contents of the Baixintan intrusion range from 81.12 to 84.46 mol.%. Numerical calculations yield a parental magma composition with 9.14 wt.% MgO. The Rayleigh simulation using olivine Fo and Ni contents shows that the parental magma of the Baixintan intrusion has experienced ~ 2% olivine crystallization, and then evolved magma became sulfide-saturated. Calculations by the mass-balance R factor equation using PGE data indicate that the formation of the mafic and mafic–ultramafic units of the Baixintan intrusion resulted from multiple influxes of magmas. The Baixintan intrusion is highly comparable with those mafic–ultramafic intrusions that host large magmatic Ni–Cu sulfide deposits in the eastern part of Eastern Tianshan. The mafic–ultramafic intrusions in the western part of Eastern Tianshan should be carefully evaluated for the potential of hosting large magmatic Ni–Cu deposits. [ABSTRACT FROM AUTHOR]

Organic matter assimilation-induced reduction is thought to play a critical role in the formation of magmatic sulfide deposits if the parental magmas are too oxidized to form Ni-Cu deposits, but the mechanism for addition of organic matter to the magma and its global significance are unclear. The Tulaergen deposit, which was formed at 280 ± 4 Ma, is one of the several major magmatic Ni-Cu sulfide deposits in the Central Asian Orogenic Belt in western China and is associated with oxidized magmas derived from a subduction-modified mantle. Three types of carbonaceous phases are recognized in the sulfide-bearing ultramafic rocks, (i) graphite enclosed in olivine grains, (ii) graphite enclosed in apatite or sulfide, and (iii) solid bitumen in veinlets among silicates. The graphite inclusions are more common than the bitumen veins. Solid bitumen is also found in the Carboniferous volcano-sedimentary rocks which host the deposit. Based on the different modes of occurrences, we interpret that the graphite formed in the magmatic stage and bitumen during the post-magmatic stage. Non-carbonate carbon extracted from the sulfide-bearing ultramafic rocks has δ13C values from − 27.6 to − 22.9‰, significantly lower than mantle values (− 7 to − 5‰), but similar to those of volcano-sedimentary rocks (− 27.5 to − 24.0‰). The anomalous C isotopic ratios are attributed to addition of organic matter via dehydration of crustal rocks during magma emplacement. Bulk assimilation of country rocks estimated using Sr-Nd isotopes is only < 5 wt.%, suggesting that the organic matter was incorporated into the magma via selective assimilation. The addition of organic matter to the magma resulted in a sudden decrease of oxygen fugacity of the magma, thereby triggering sulfide over-saturation in the magma. No correlation is observed between δ13C values and estimated magmatic oxygen fugacities (fO2) for the Tulaergen deposit, which could be due to highly variable δ13C values in the contaminants. The δ34S values of sulfide ores are from − 1.3 to 3.8‰, within the range (− 2.6 to 4.5‰) of pyrite grains in the volcano-sedimentary rocks, suggesting that the country rocks could have supplied some sulfur to the magma. Our results propose that selective assimilation of organic matter, even for low abundance organic carbon in country rocks, could play a key role in causing sulfide saturation in highly oxidized mafic magma. [ABSTRACT FROM AUTHOR]

Chinese magmatic copper-nickel-cobalt sulfide deposit is the main source of strategic key metal resources, such as nickel, cobalt and platinum group elements in China, and it is an important deposit type with a future value that needs special attention. This type of deposit comes from the mafic and ultramafic magma formed by the upper mantle, especially the asthenosphere, and the immiscible (liquation) action between sulfide liquid -silicate melt is the main mineralization mechanism. They are mainly formed in two geological settings: the continental rift and the extended environment in the orogenic zone. China is a major producer of magmatic copper-nickel-cobalt sulfide deposits, but compared with the world it is relatively unique. Most magmatic copper-nickel-cobalt sulfide deposits in the world are formed in the ancient craton, and are the result of the mantle plume geodynamics. Archeozoic-early Proterozoic komatiite nickel-cobalt sulfide deposits is a distinct metallogenic characteristics. Ancient komatiite-related nickel-cobalt sulfide deposits have been rarely discovered in China, and their mineralization age is relatively late, mainly in the Neoproterozoic, Early and Late Paleozoic. The Neoproterozoic is represented by the Jinchuan super-large deposit with nickel metal reserves ranked the third in the world, and the Early Paleozoic by the Xiarihamu super-large deposit discovered in the prospecting breakthrough of recent years. The Xiarihamu deposit is also the only super-large magmatic copper-nickel-cobalt sulfide deposit found in the Tethys orogenic belt in the world. Mineralization theory of "big magma-deep immiscibility-injection" and "forming big ore deposits in small intrusive rocks" proposed by Chinese scholars based on China's prospecting practice has been widely accepted and applied by field geological exploration workers, and has made important prospecting breakthrough discoveries. At the same time, it has been recognized by foreign peers, which changed the traditional metallogenic understanding of magma copper-nickel-cobalt sulfide deposits. The extensive distribution of magmatic copper-nickel-cobalt sulfide deposits in orogenic belts is an important feature of such deposits in China. According to the different evolution of orogenic zones and metallogenic history, it can be divided into two important types: Tethys type and Central Asian type. The Tethys type is represented by the Xiarihamu ore deposit, and it is the product of the Tethys structural transformation, which the Paleo-Tethys cracking after the Proto-Tethys orogeny; the Central Asian type is represented by a large number of the early Permian of the Late Palaeozoic magmatic copper-nickel-cobalt sulfide deposits distributed in the Eastern Tianshan-Beishan and Altai zones of the Central Asian Orogenic belt, which is the result of the dual geodynamics mechanism of plate tectonics and mantle plume. China's magmatic copper-nickel-cobalt sulfide deposit has huge prospecting potential, and the Jinchuan deposit as a result of nappe structure from deep horizontal "sill" thrusted to the surface of the inclined "dyke", it still has significant prospecting potential in its deep and marginal locations, in which important new ore bodies have been found at both ends of the ore-bearing rock body; more than 10 new ore deposits (points) have been found in East Kunlun and its adjacent areas, where the Xiarihamu deposit is located. In the region, the southeastern margin of Tarim Landmass, the northern margin of Tarim Landmass, the western margin of Yangtze Landmass and the northeast margin of North China Landmass are the exploration prospect areas to strengthen prospecting, while the northern margins of Yangzi Landmass and North China land block are the new prospecting areas for urgent investigation. [ABSTRACT FROM AUTHOR]

The Hongqiling‐Piaohechuan region in the east Central Asian Orogenic Belt (CAOB) is an economically important Ni–Cu sulphide mineralization region in China. It is widely accepted that these Ni–Cu sulphide deposits mainly formed during the Late Triassic period. The early Middle Triassic mafic‐ultramafic plutons are therefore key in understanding the mineralization process. Here, we report the laser ablation inductively coupled plasma mass spectrometer (LA‐ICP‐MS) U–Pb dating of zircon and geochemical data for two Middle Triassic mafic‐ultramafic plutons and one felsic pluton in central and eastern Jilin Province, NE China. The mafic‐ultramafic plutons are composed of gabbronorite and olivine websterite. Zircon dating results indicate that these mafic‐ultramafic plutons crystallized at 243 ± 1 to 245 ± 1 Ma in the Middle Triassic. The coeval felsic pluton is mainly quartz diorite. Zircon dating results indicate that the felsic pluton crystallized at 239.7 ± 0.63 Ma in the later period of Middle Triassic. The mafic‐ultramafic plutons are low in SiO2 (43.49–49.66 wt%), depleted in K2O (0.28–2.74 wt%) and Na2O (0.70–1.18 wt%). They have low rare earth element (REE) abundances without Eu anomalies, exhibit depletion in high‐field‐strength elements (HFSEs), and hold various εHf(t) values (−15.3 to +2.9). These findings suggest that the primary magma of mafic‐ultramafic plutons was derived from the partial melting of the depleted lithospheric mantle, metasomatized by subducted‐slab‐derived fluids/melts. Remarkably, these mafic‐ultramafic plutons have extremely high Cu–Ni contents (23.6–669.4 and 419–1,956 ppm, respectively). The coeval quartz diorites have 59.55–64.86 wt% of SiO2, 3.02–4.21 wt% of K2O and 3.97–4.49 wt% of Na2O. They are enriched in light REEs (LREEs) and large‐ion lithophile elements (LILEs); depleted in heavy REEs (HREEs) and HFSEs, and they have εHf(t) values in the range −6.4 to +2.9. Additionally, the felsic rocks exhibit adakitic‐features with high Sr/Y (28.5–58.7) and (La/Yb)N (4.9–12.2) ratios, implying the thickening crustal sources of the North China Craton (NCC) and CAOB, respectively. The above findings, combined with the regional geological data, suggest that the Middle Triassic mafic‐ultramafic plutons are the prelude to the large‐scale Late Triassic mineralization. This was induced by the thickening event of the later period of Middle Triassic felsic rocks, accompanying the final closure of the Palaeo‐Asian Ocean (PAO) in the eastern CAOB. [ABSTRACT FROM AUTHOR]

As the application of the rhenium–osmium (Re‐Os) chronometer in low‐level (low Re mass fraction) sulfides becomes more popular, there is increasingly a need for a corresponding reference material for analytical quality control. This study presents a new low‐level, highly radiogenic chalcopyrite reference material for Re‐Os geochronology. Chalcopyrite was acquired from the Xiaotongchang (XTC) copper deposit in Yun'nan Province, China. Homogeneity tests were used by performing Re‐Os analyses on eleven randomly selected aliquots of powdered chalcopyrite using ICP‐MS. We also performed stability tests on four bottles of powdered chalcopyrite samples over a period of 36 months. The results from analysis of variance and Student's t‐test indicated that the XTC sample was homogeneous with respect to Re, 187Os mass fractions and model age. Three laboratories participated in an inter‐laboratory comparison scheme for certification, performed using N‐TIMS and MC‐ICP‐MS, and employing two different spiking techniques. The reported values for model ages obtained for the XTC chalcopyrite in this study resulted in an age RM value of 229.3 ± 3.7 Ma at the 95% confidence level (95% conf.). Additionally, Re and 187Os mass fractions of 26.5 ± 1.9 ng g−1 and 63.7 ± 4.7 pg g−1 (95% conf.), respectively, are also reported, providing further information values. [ABSTRACT FROM AUTHOR]

The Yaojialing Zn-Au‑Cu deposit is a porphyry-skarn-epithermal vein-type compound deposit that consists of epithermal vein-type lead‑zinc‑silver orebodies, skarn Zn-Cu-Au orebodies, and porphyry Cu Au orebodies from shallow level to depth. We decipher the source and metallogenic mechanism by studying the trace element and S isotopic compositions of sulfides (pyrite, sphalerite, chalcopyrite, and galena) from three types of orebodies. The collected pyrite can be divided into two types. PyI coexists with chalcopyrite, and PyII coexists with sphalerite or galena. In addition, PyI was further divided into PyIa (collected from porphyry copper bodies) and PyIb (collected from skarn copper bodies). PyII can be further divided into PyIIa (collected from skarn-type lead‑zinc ore body) and PyIIb (collected from vein lead‑zinc ore body in strata). Sphalerite and galena from skarn-type Pb Zn ore bodies and shallow vein-type Pb Zn ore bodies are named SpI and GnI, and SpII and GnII, respectively. Pyrite and sphalerite trace element thermometers revealed that the temperature of the ore-forming fluids decreased from 500 to 600 °C in the porphyry ore body to 300– 360 °C in the skarn ore body and then to 240– 280 °C in the shallow vein ore body. The decrease in the Co and Ni contents of pyrite collected from deep to shallow depths may indicate that meteoric water precipitated in the late ore-forming hydrothermal system. Rapid crystallization and variations in the physicochemical states (such as temperature, pH, fO 2 , and geochemical composition) of the fluids resulted in an obvious oscillating zone of euhedral PyI pyrite particles. It also affects the solubility of trace metal elements and leads to the selective entry of these elements into pyrite. PyII also shows obvious zonation characteristics rather than oscillating zonation, indicating that the growth rate of pyrite is relatively slow. Moreover, the relationships between the Au and As contents in the two types of pyrite are different. PyI is coupled, while PyII shows decoupling. We believe that this phenomenon is due to the high content of As in ore-forming fluid systems, which may inhibit the absorption of Au on the surface of pyrite rather than the decoupling of Au and As caused by rapid crystallization, based on the rapid increase in As content and non-oscillating zonation in PyII. According to the analysis of the sulfur isotopes of various sulfides, the solid evidences suggest that the ore-forming materials of each type of orebody in the Yaojialing deposit were mainly derived from magmatic-hydrothermal processes and that the fractionation of sulfur isotopes was the result of variations in physicochemical conditions caused by magma-hydrothermal evolution rather than the addition of foreign sulfur sources. [Display omitted] • Yaojialing deposit mainly derived from magmatic hydrothermal fluid • High content of As may inhibit the absorption of Au on the surface of pyrite. • Trace element scanning of pyrite can reflect hydrothermal evolution and metallogenic history [ABSTRACT FROM AUTHOR]

Mercury (Hg) isotopes have shown their power of tracing Hg pollution sources in ecosystems, but their potentials for petrogenetic tracing are yet to be explored. Here we conducted Hg isotope analysis for samples collected from major orebodies of the world‐class Jinchuan Ni‐Cu sulfide deposit, China. These samples show large variations of δ202Hg (−2.65 to +0.19‰) and Δ199Hg (−0.16 to +0.19‰). Some of the Δ199Hg values significantly deviate from current estimates on the primitive mantle (Δ199Hg: 0.0 ± 0.1‰, 2SD). The pronounced Hg mass‐independent fractionation (Hg‐MIF) signals, with significant positive (>0.1‰) and negative (<0.1‰) Δ199Hg values similar to marine sediments and terrestrial soils, respectively, suggests the addition of crustal materials into the Jinchuan deposit, via crustal assimilation during mantle‐derived magma ascending to the crust. These samples show δ34S values (−1.09 to +1.38‰) identical to that of the primitive mantle (0.0 ± 2.0‰), which may indicate a major sulfur source from the mantle. However, δ34S provides poor constraints on the sulfur source, and the early reported anomalous Δ33S values (+0.12 to +2.67‰) in the Jinchuan deposit support the involvement of external sulfur from Archean and Proterozoic sedimentary rocks during the formation of this deposit, similar to the case of Hg. This study shows the powerful use of Hg isotopes as a petrogenic tracer and highlights the importance of interaction between mantle‐derived magmas and crustal materials on the formation of the Jinchuan Cu‐Ni sulfide deposit. Plain Language Summary: Photochemical reactions result in pronounced Hg mass‐independent fractionation (Hg‐MIF) signals (Δ199Hg ≠ 0‰) in marine and terrestrial systems. Recent estimates on 3He‐rich basalts suggest the lack of Hg‐MIF signals in the primitive mantle (Δ199Hg ∼ 0‰). This study observes non‐zero Δ199Hg values (−0.16 to +0.19‰) in the giant Jinchuan Ni‐Cu sulfide deposit, suggesting crustal assimilation during the formation of this deposit. Interaction between mantle‐derived magmas and crustal materials could have played an important role in the formation of the Jinchuan Cu‐Ni sulfide deposit. Hg isotopes have a great potential in understanding crustal‐mantle interactions. Key Points: Significant Hg mass‐independent fractionation signals were observed in the giant Jinchuan Ni‐Cu sulfide depositThe non‐zero Δ199Hg values in the Jinchuan deposit suggest crustal contamination mantle‐derived magma ascendingCrustal materials addition plays an important role in the formation of magmatic sulfide deposits [ABSTRACT FROM AUTHOR]

The Baiyinnuo'er deposit in northern China is located in the south section of the Great Xing'an Range, and it is the largest skarn Zn–Pb deposit in the region. Skarn and Zn–Pb orebodies mainly occur between the different units of the Permian Huanggangliang Formation, or within the contact zone between the intrusive rocks and the marble. Although Baiyinnuo'er has been well investigated previously, the timing of the Zn–Pb mineralization is still controversial, largely due to the lack of appropriate ore or alteration minerals that could be directly used for isotopic dating. In this study, we report the results of Rb–Sr isotopic analysis for sphalerite and pyrite samples from the Baiyinnuo'er orebodies, which yielded two isochron ages of 137.4 ± 3.4 and 140.0 ± 7.8 Ma, respectively, constraining the Zn–Pb mineralization time of the deposit as the Early Cretaceous. The data are also consistent with the age of the granitoids in the mining area, indicating a potential genetic relationship between the Early Cretaceous magmatism and mineralization. Many other intrusion-related hydrothermal deposits (including the two typical skarns, Huanggang and Haobugao) in the southern Great Xing'an Range also share similar mineralization ages (i.e., 140–130 Ma). Together, these data suggest an Early Cretaceous mineralization event in this region, and this large-scale mineralization could be related to the regional tectonic regime transition from compression to extension as a result of the rollback of the subducted Paleo-Pacific plate. The initial 87Sr/86Sr ratios of the sphalerite and pyrite samples are 0.70569 and 0.70616, respectively, implying that the ore-forming material could have a significant contribution from the mantle components. The current study shows that sulfide Rb–Sr dating could be used in deciphering the timing of skarn deposit formation. [ABSTRACT FROM AUTHOR]

A zinc smelter in northwestern China obtains sulfur products and hot filter residues after wet smelting and flotation processes. The hot filter residue is smelting solid waste produced by leaching, which is rich in valuable metals such as zinc, gold and iron, and elemental sulfur is the main component, with a content of about 52%. Treating the hot filter residue by alkali leaching can reduce the sulfur content in the hot filter residue, and the generated sodium sulfide combines with other metal elements in the hot filter residue to form sulfide salts, thereby achieving the enrichment of valuable metal elements in the residue and reducing solid waste emissions. The process provides a feasible technical route in terms of economic benefits, process technology, etc., which can realize the efficient enrichment of valuable metals and produce high-performance product sodium sulfide. The sodium sulfide product was used for the coppet-molybdenum separation test and compared with industrial sodium sulfide. The coppermolybdenum separation tost was carried out with the sodium sulfide obtained by high-alkali multiple leaching, and the separation index was excellent, and the separation effect was basically the same as that of industrial sodium sulfide. It can be used in the industrial application of copper-molybdenum separation, providing a technical reference for processing this type of hot filter residue. [ABSTRACT FROM AUTHOR]

The Aobaotu Pb–Zn deposit (470,700 t; 1.51% Pb, 2.30% Zn) in the southern Great Xing'an Range, northeastern China, is hosted by the Late Jurassic volcanic tuff and structurally controlled by a near‐east–west‐trending fault. Three stages of mineralization were identified, namely, stage I of quartz ± pyrite veins, stage II of quartz–polymetallic sulphide veins, and stage III of late quartz–calcite veins. The quartz and calcite that formed in the three stages were selected for fluid inclusion and C–H–O isotope analyses. The results show that the ore‐forming fluid of the deposit belongs to the H2O–CO2–NaCl system at a medium temperature (concentrated at 220–300°C) and in low salinity (0.7–12.1 wt% NaCl equiv). The δ13C values of the calcite and ankerite are in the range of −8.4 to −4.8‰, indicating that as a source of deep magma. The δDV‐SMOW and δ18OH2O values of quartz range from −108 to −88‰ and 4.55 to 5.85‰, respectively, indicating that the initial fluid of the Aobaotu deposit was a mixture of residual magmatic and meteoric water. Sulphur isotope analysis of the sulphide minerals, that is, sphalerite, galena, pyrite, and chalcopyrite, yield δ34S value in a range of 1.44–4.94‰, indicating that sulphur is mainly derived from magma. In addition, the Pb isotopic composition of the sulphides indicates that the ore‐forming material has a mixed crust–mantle source. Zircon U–Pb dating suggests that the formation of the Aobaotu deposit is genetically related to the granodiorite porphyry (130.3 ± 0.9 Ma). The combined geochronology and isotopic evidence suggest that the Aobaotu deposit is a magmatic‐hydrothermal vein‐type Pb–Zn deposit, opposite to a volcanic Pb–Zn deposit as suggested before. The Aobaotu deposit formed in an extensional tectonic setting caused by the rollback of the Palaeo‐Pacific Plate. [ABSTRACT FROM AUTHOR]

A Cu-rich mantle source may play a key role in generating giant magmatic Ni-Cu deposits worldwide, but evidence for the source's Cu enrichment and its mechanism is still rare. Copper isotopes can provide novel and direct insights into this issue since metasomatism that causes Cu enrichment in the mantle is commonly associated with a huge Cu isotope fractionation. Here we present the first Cu isotopic study on the world-class Jinchuan magmatic Ni–Cu deposit in China, including disseminated, net-textured, and massive sulfides. The disseminated and net-textured sulfides have variable δ65Cu values (+0.36 ± 0.38‰, n = 42), which are higher than those of massive sulfides (−0.44 ± 0.28‰, n = 11). The country rocks have a narrow δ65Cu range of 0.21 to 0.23‰, which is unlikely to have caused the large δ65Cu variations. The absence of a relationship between δ65Cu and whole-rock Cu contents rules out the possibility of surface weathering and diffusion-driven processes. Furthermore, the lack of correlation between δ65Cu and whole-rock Cu/Ni and Pd/Ir ratios excludes large Cu isotopic variations as a result of the progressive evolution of parental magma or sulfide melt. Numerical modeling indicates that the initially segregated sulfide melt has a mean δ65Cu of 0.44 ± 0.22‰ (2SD). Sulfide-liquid fractionation could have contributed to the enrichment of 65Cu in the Cu-rich net-textured sulfides and depletion of 65Cu in massive sulfides, respectively. The fractionated sulfide melts were fragmented and assimilated by new magma pluses, and consequently, the new segregated sulfide melts acquired lighter and more variable δ65Cu values in comparison with the initially accumulated sulfide melts. The estimated Cu isotopic composition of parental magmas for the Jinchuan Ni-Cu deposit is 0.54 ± 0.22‰ (2SD), which is up to ~0.5‰ higher than the mantle value. Copper transportation from oxidized subducted slabs to mantle peridotites and/or dissolution of Cu-bearing sulfides in the mantle caused oxidative breakdown and reprecipitation of sulfides and shifted the hybridized mantle source toward heavy δ65Cu as previously observed in mantle xenoliths. Our study, therefore, suggests that the source's pre-enrichment is a key step in the generation of giant magmatic Ni-Cu deposits. [ABSTRACT FROM AUTHOR]

This study explores the effects of high-pressure crystallization and immiscible sulfide melt segregation under mantle conditions on the compositional variation of basaltic magmas, using clinopyroxene megacrysts in the Cenozoic basalts of eastern China. These clinopyroxene megacrysts are large (up to >10 cm in size) and homogeneous at the grain scale. They were crystallized from variably evolved parental magmas and then captured by their host basalts. The large and systematic variations of [Sm/Yb]N, Lu/Hf, Fe/Mn, Sc/La, Ni and Cu with Mg# in the clinopyroxene megacrysts suggest their co-precipitation with garnet and with immiscibility between sulfide and silicate melts. This is consistent with the appearance of garnet megacrysts in the host basalts and abundant sulfide globules in the clinopyroxene megacrysts. The covariation between Ni contents of sulfide globules and Mg# of the clinopyroxene megacrysts suggests a genetic relationship between sulfide globules and clinopyroxene megacrysts. High-pressure crystallization of clinopyroxene and garnet results in decrease of Mg# and concentrations of CaO, MnO and heavy rare earth elements (e.g. Yb) and increase of Fe/Mn and [Sm/Yb]N in the residual melts. Therefore, geochemical characteristics of low Mg#, low CaO and MnO contents and high Fe/Mn and [Sm/Yb]N in basalts do not necessarily indicate a pyroxenite mantle source. In addition, caution is needed when applying the olivine addition method to infer the primary compositions of alkali basalts without considering the effects of high-pressure crystallization of clinopyroxene and garnet. The calculated pressure (P) and temperature (T) conditions of the clinopyroxene megacrysts are close to those of the lithosphere–asthenosphere boundary (LAB) beneath eastern China, and the low primitive [Sm/Yb]N (~4.0) of melts parental to the clinopyroxene megacrysts suggests final equilibration at relatively low pressures most likely beneath the LAB. Hence, a melt-rich layer is expected close beneath the LAB. Melt pools in this melt-rich layer provide a stable and closed environment for the growth of compositionally homogeneous clinopyroxene megacrysts. As a result, melts in these melt pools are compositionally evolved with low and variable Mg#. Subsequent pulses of melt aggregation/supply from depths with primitive compositions and high Mg# will disturb these melt pools, cause magma mixing and trigger the eruption of magmas carrying clinopyroxene and garnet megacrysts. [ABSTRACT FROM AUTHOR]

The Tulaergen magmatic Ni-Cu sulfide ore deposit is located along the southern margin of the Central Asian Orogenic Belt in northwestern China. This deposit is hosted by a small mafic–ultramafic complex composed of a Late Carboniferous (~ 301 Ma) gabbroic member at the margin and a younger ultramafic dyke in the center. Net-textured and semi-massive sulfides are mainly concentrated in the steeply dipping, widened parts of the dyke. Zircons from the ultramafic member yield a U–Pb age of 281 ± 2 Ma, ~ 20 myr younger than the gabbroic member. The average εHf(t) value of the zircons is ~ 16. The Tulaergen mafic–ultramafic rocks are characterized by light REE enrichments, pronounced negative Nb–Ta anomalies, (87Sr/86Sr)i ratios from 0.7034 to 0.7036, and εNd(t) values from 5.1 to 6.9. The isotope data indicate negligible bulk contamination with the crust. The δ34S values of sulfide ores are from − 0.3 to 1.5‰, similar to the values of the country rocks. The γOs values of the sulfide ores are from + 605 to + 954, much higher than typical mantle values. The Os-S isotope data together support the view that the addition of Os-bearing organic matter from the country rocks may have played a critical role in triggering sulfide saturation. In the sub-vertical segment of the deposit, the upper zone has lower PGE tenors coupled with lower and rather constant olivine Fo contents compared to the lower zone. Based on the geometry of the dyke and sulfide distribution, we conclude that the Tulaergen deposit formed in a dynamic magma conduit. [ABSTRACT FROM AUTHOR]

Magmatic Ni-Cu sulfide deposits in orogenic belts have distinct petrological and geochemical features compared with world-class intraplate magmatic deposits. One such feature is the presence of abundant primary hydrous minerals such as phlogopite and amphibole, indicating a H2O-rich parental magma. However, the origin and nature of the fluids have not been established. In the southern Central Asian Orogenic Belt, the Permian Baishiquan and Tianyu mafic–ultramafic intrusions host magmatic Ni-Cu sulfide deposits. Both intrusions are composed of lherzolite, olivine websterite, gabbronorite, gabbro, and diorite. The main ore-host rocks are lherzolite and websterite, with disseminated, net-textured, and massive ores comprising the dominant primary ore types. Low zircon εHf (− 6.9 to 7.9 ‰) and varying δ18O values (5.2 to 6.6 ‰), as well as both arc-type and MOR-type zircon Nb/Yb (0.0013–0.011) and U/Yb (0.33–10.22), identify an altered lower oceanic crust component in the mantle source. A combination of altered lower oceanic crust and upper crust can account for the zircon Hf–O isotopic characteristics. A mixing model further reveals that the Baishiquan and Tianyu magmatic sulfide deposits originated from a depleted mantle source that experienced two stages of subduction metasomatism with a 30% addition of altered oceanic crust in the first stage and 20% in the second. In the second stage, > 10% oceanic sediment with high δ18O must also have been added to result in olivine δ18O values higher than those in mantle. This staged evolution is reflected in both the olivine and zircon signatures with olivine from disseminated and net-textured ores at the Tianyu deposit having high δ18O (4.6 to 6.3 ‰) with a similar range to zircon and high δ7Li isotopic compositions (12.03 to 19.46 ‰). Contamination in the source by oceanic sediment with high δ18O values can account for the olivine δ18O values (4.8 to 5.7 ‰ at Baishiquan) being higher than those in the mantle, while the addition of brine (5% at the Baishiquan deposit) can explain the olivine δ7Li values (20.96 to 31.01 ‰). The results suggest that H2O content, Li content, and δ7Li and δ18O isotopic signatures in olivine and zircon are good indicators of mantle metasomatism and olivine fluid processes in magmatic Ni-Cu sulfide deposits. [ABSTRACT FROM AUTHOR]

Purpose: The Spartina alterniflora invasion across the southeast coast in China significantly reduced vegetation diversity and generated associated ecological problems. Sulfur (S) is a vital nutrient, while sulfide is phytotoxic and the impact of S. alterniflora invasion on soil S cycle remains unclear. Therefore, this study aims to investigate the impacts of S. alterniflora invasion on the S cycle and associated soil microbial communities. Methods: Both field investigation and lab-scale experiments were conducted, analyzing soil sulfide and sulfate contents, soil properties over four seasons in the Jiuduansha Wetland of Shanghai, China, the high-throughput sequencing of soil microbial communities, S cycle-related functional genes and seed germination experiments. Results: The contents of sulfide, soil organic carbon (SOC), and total nitrogen (TN) in the bulk soil of S. alterniflora invaded area were higher than those in the native species S. mariqueter habitat and bare mudflat soils. Spartina alterniflora invasion increased the abundance of the Nitrospiraceae and Desulfarculaceae families and reduced that of Hydrogenophilaceae. The relative abundance of the SO42− reduction functional genes (dsrA + dsrB) in the soil was increased after S. alterniflora invasion, while that of the S oxidation functional genes (yedZ + soxY) in the soil was reduced. Seed germination experiments with different sodium sulfide concentrations (Na2S) revealed that the phytotoxicity of sulfide caused more lethal damage to S. mariqueter than to S. alterniflora. Conclusion: The S. alterniflora invasion significantly increased SOC and TN contents and reduced the abundance of sulfur-oxidizing functional genes, which led to the accumulation of soil sulfide. [ABSTRACT FROM AUTHOR]

Microbial and hydrothermal venting activities on the seafloor are important for the formation of sediment-hosted stratiform sulfide (SHSS) deposits. Fe isotopic compositions are sensitive to both microbial and hydrothermal activities and may be used to investigate the formation of these deposits. However, to the best of our knowledge, no Fe isotopic studies have been conducted on SHSS deposits. In the Devonian Dajiangping SHSS-type pyrite deposit (389 Ma), South China, laminated pyrite ores were precipitated from exhalative hydrothermal fluids, whereas black shales were deposited during intervals with no exhalation. Pyrite grains from black shales mostly display positive δ56Fe -py (0.01–0.73‰), higher than marine sediments (ca. 0‰), due to pyrite deriving Fe from basinal shuttled Fe(III) (hydr-)oxides and slowly crystallizing in pores of sediments with equilibrium fractionation, except for negative δ56Fe -py (−0.17‰ to −0.24‰) of two samples caused by mixing of Fe from underlain laminated ores. The positive δ34S -py (3.50–24.5‰) of black shales reflect that sulfur of pyrite originated from quantitative reduction of sulfate in closed pores of sediments. In contrast, pyrite grains of laminated ores have negative δ56Fe -py (−0.60‰ to −0.21‰), which were not only inherited from the negative δ56Fe of hydrothermal fluids but also caused by kinetic fractionation during rapid precipitation of a pyrite precursor (FeS) in hydrothermal plumes. These ores have negative δ34S -py (−28.7‰ to −1.82‰), because H 2 S for pyrite mineralization was produced by bacterial sulfate reduction (BSR) in a sulfate-rich seawater column or shallow sediments. The δ56Fe -py values of laminated ores co-vary positively with δ34S -py and δ13C -carbonate along the ore stratigraphy, with δ13C -carbonate values ranging from −12.0‰ to −2.50‰. However, they correlate negatively with aluminum-normalized total organic carbon (TOC/Al 2 O 3). Organic carbon is thus considered to enhance the production of H 2 S by BSR activities, increase pyrite precipitation rates and promote the expression of kinetic fractionation of Fe isotopes. Intriguingly, in the ore units with vigorous hydrothermal venting activities, δ56Fe -py , δ34S -py and δ13C -carbonate values display a consistently increasing trend. Such results suggest that venting hydrothermal fluids significantly inhibited the H 2 S production of BSR, which then reduced the pyrite crystallization rate and decreased the kinetic fractionation of Fe isotopes. Our study reveals that the formation of SHSS deposits relies on H 2 S from microbial activities and metals from hydrothermal exhalation on the seafloor, but that vigorous exhalation can inhibit microbial activities and thus sulfide precipitation rates. The integrated use of Fe, S, and C isotopes can effectively elucidate these dynamic interactions between hydrothermal venting and microbial activities during the formation of SHSS deposits. [ABSTRACT FROM AUTHOR]

Shitoukengde is an important magmatic Ni–Cu sulfide deposit in the Eastern Kunlun Orogenic Belt (EKOB). It comprises several mafic–ultramafic complexes and contains different kinds of mafic–ultramafic rocks. Lherzolite and olivine websterite are the most significant Ni–Cu‐hosted rocks. The No. I complex hosts six Ni–Cu ore bodies, and the depth of the intrusion has great exploration potential. Therefore, geochronology, geochemistry, and mineral chemistry of the Shitoukengde deposit were studied to constrain its mineralization time, parental magma composition, and crustal contamination process. Zircon U–Pb dating of olivine websterite shows the magmatic origin (Th/U = 0.40–1.05) and an age of 418.1 ± 8.7 Ma (MSWD = 0.01), which is coeval with the Xiarihamu, Akechukesai, and other Cu–Ni deposits in the EKOB. Geochemically, the mafic–ultramafic rocks are characterized by low SiO2, TiO2, and Na2O + K2O and high MgO (9.49–36.02%), with Mg# values of 80–87. They are relatively enriched in LREE and LILEs (e.g., K, Rb, and Th), with weakly positive Eu anomalies (δEu = 0.83–2.26), but depleted in HFSEs (e. g., Ta, Nb, Zr, and Ti). Based on the electron microprobe analyses, all of the olivines are chrysolite (Fo = 81–86), and the pyroxenes are dominated by clinoenstatite (En = 80–84) and augite (En = 49–55) in the mafic–ultramafic rocks. Therefore, the composition of parental magma is estimated to be picritic basaltic magma with SiO2 and MgO concentrations of 54.47 and 13.95%, respectively. The zircon εHf(t) values of olivine websterite vary from −0.8 to 4.6, with a TDM1 of 0.84–1.06 Ga, indicating that the parental magma was derived from relatively high degree partial melting (about 13.4%) of a depleted mantle source and experienced significant crustal contamination (about 12–16%). We propose that crustal assimilation, rather than fractional crystallization, played a key role in triggering the sulfide saturation of the Shitoukengde deposit, and the metallogenesis of "deep liquation–pulsing injection" is the key mechanism underlying its formation. The parental magma, before intruding, underwent liquation and partial crystallization at depth, partitioning into barren, ore‐bearing, and ore‐rich magma and ore pulp, and was then injected multiple times, resulting in the formation of the Shitoukengde Ni–Cu deposit. [ABSTRACT FROM AUTHOR]

Archean magmatic Ni‐Cu‐[platinum‐group element (PGE)] deposits are very important and mainly associated with komatiitic rocks in intracratonic rift zones throughout the world. However, the Taoke Ni‐Cu‐(PGE) deposit in the North China Craton, which is the oldest (Neoarchean, 2,537 Ma) magmatic sulphide deposit in China, and is genetically related to the subduction zone. The intrusion is predominantly composed of a small ultramafic body (olivine websterite) and a much larger gabbroic body (gabbronorite). Sulphide mineralization is mainly associated with the ultramafic body with average grades of 0.66 wt% Ni, 0.62 wt% Cu and ~1 g/t PGE. Sulphides of the Taoke deposit are characterized by a chalcopyrite + pentlandite + pyrrhotite + millerite assemblage, which hosts variable amounts of platinum‐group minerals. Good correlations are found for Pd versus individual Ir subgroup of platinum‐group elements (IPGEs; i.e., Pd vs. Os, Ir, Ru, and Rh) and for Ir and Pd subgroup of platinum‐group elements (PPGEs; i.e., Ir vs. Pt and Pd), indicating that the PGE contents of immiscible sulphide liquids in the Taoke deposit are mainly controlled by the initial PGE concentrations in the parental magma and R factor (magma/sulphide mass ratio). Based on our calculations, the initial contents of Ir and Pd in the parental magma are estimated to be 0.13 and 5.6 ppb, respectively, suggesting that the parental magma of the Taoke deposit is PGE undepleted. The multiple sulphur isotopes can provide direct indications of the source of sulphur for the Archean intrusion. The γOs(t) values and Archean crustal sulphur (three samples have anomalous Δ33S values <−0.1‰) suggest that the addition of crustal sulphur occurred in the magma. Fractional crystallization and the addition of crustal sulphur are the most likely key factors for sulphide saturation in the Taoke mafic magma. [ABSTRACT FROM AUTHOR]

Highly Siderophile Elements (HSEs; Os, Ru, Ir, Rh, Pt, Pd, Au and Re) combined with their isotopic systematics (Re-Os and Pt-Os) are powerful tools for tracking evolution and genesis of mantle derived magmas. Given sulfides (accessory sulfide minerals and/or molten sulfides) are the primary hosts of HSEs in the mantle and low-degree carbonated melts are extracted from large portions of mantle volume, partitioning of HSEs between sulfide and carbonated melt might play a critical role in distributing HSEs between the mantle and crustal reservoirs. Although, partitioning of HSEs and chalcophile elements between sulfide melt and silicate melt has been previously studied, partitioning of these elements between sulfide melt and carbonated melts has not received much attention. Here we use high P-T experiments to determine the partitioning of HSEs and chalcophile elements (Ni, Co, Mo, Os, Ru, Pd, Pt and Re) between (i) sulfide melt and carbonated silicate melt (CO 2 ~ 17 wt.%) and (ii) sulfide melt and carbonatitic melt (CO 2 ~ >30 wt.%) at a pressure (P) of 3 GPa and temperatures (T) of 1300–1600 °C in graphite capsules. All experiments produced quenched Fe-sulfide melt blobs + carbonated silicate melt matrix. Concentrations of major elements were measured using electron microprobe, and HSEs and chalcophile elements were measured using LA-ICP-MS. We find that all the elements measured are compatible in the sulfide melt to varying degrees and their D sulfide/carb. melt sequence is Mo < Co < Ni < Re < Pt ≤ Pd < Ru ≤ Os varying from around 10 for Mo to 105 for Os. Comparing the D sulfide-carb. melt with D sulfide-silicate from previous studies, we show that the partition coefficients of HSEs between sulfide and carbonated melts are lower than the partition coefficients of these elements between sulfide and silicate melts, indicating greater mobilization of these elements in carbonatites and carbonated silicate melts. Calculating bulk D (D ¯) for carbonated peridotite using our experimentally measured D values, we model the HSE contents of mantle derived low-degree partial melts using an aggregate fractional melting equation and compare the primitive mantle normalized HSE patterns of our model with natural kimberlites, carbonatites, ocean island basalts, and alkaline basalts. We also calculate proportions of sub-lithospheric continental mantle (SCLM) xenolith detritus in the natural kimberlite and carbonatite samples from Karelian, Kaapvaal, Canadian shield and North China craton by using mass balance calculations based on Ru concentration in the primary carbonated melt and the SCLM xenoliths. Our calculations show that detritus proportion in natural kimberlites are 2–28% for Karelian, 7–28% for Kaapvaal, and 6–16% for Canadian shield, which are in agreement with previous studies using various other proxies. We also show that the extent of Re/Os fractionation is less for events of carbonate melt metasomatism as compared to similar events of basaltic melt metasomatism. [ABSTRACT FROM AUTHOR]

Both India and China are 'Pioneer investor' nations for Deep Seabed Mining (DSM). Both these nations commenced their exploration quest of the deep seabed at nearly the same time and today are one of the few nations persisting with DSM. These notwithstanding, the developments made by China in this comparative period are many magnitudes more than that made by India. While India has limited its research to the Indian Ocean Region (IOR), China has gone global to win five exploration contracts from the International Seabed Authority (ISA). China is also rated as the first country that would commence exploitation once the exploitation rules are promulgated by the ISA. In going global, China has the exploration rights in the Indian Ocean for polymetallic sulphides with efforts to acquire some more Area in this oceanic space. While China grows technologically in the field of DSM and deploys its assets in the IOR, it is adding to the already skewed threat perception thereby becoming a matter of security concern for India. It is with this understanding that the article aims to look at the developments made and the involvement of China in the IOR for DSM and their resultant security implications for India. [ABSTRACT FROM AUTHOR]

• The mantle source of Huangshandong and Erhongwa have different contribution of slab-derived fluids. • Erhongwa has experienced early sulfide saturation and removal during emplacement. • High oxygen fugacity and water content of Erhongwa is due to assimilation of hydrous materials. • Evolution in deep magma chamber is favorable for magmatic sulfide mineralization in convergent margin setting. Numerous Permian mafic-ultramafic intrusions are situated in the eastern Tianshan Orogen at the southern margin of the Central Asian Orogenic Belt. These intrusions demonstrate a diverse range of magmatic Ni-Cu sulfide mineralization. Notably, the Huangshandong intrusion hosts a large Ni-Cu sulfide deposit, whereas the Erhongwa intrusion lacks any economically significant sulfide mineralization. Both intrusions exhibit similar lithologies and mainly consist of lherzolite, gabbro, gabbronorite and diorite. To elucidate the controlling factors influencing the disparity in mineralization between two intrusions, analyses were conducted on the compositions of olivine, spinel, pyroxene and amphibole. Olivine grains from the Erhongwa lherzolite have lower Ni (361–943 ppm) contents than those from Huangshandong layered lherzolite (Ni 684–864 ppm) and Huangshandong massive lherzolite (Ni 1218 to 1878 ppm). This discrepancy may be attributed to early sulfide separation occurring at greater depths. Modeling results indicated that for the Huangshandong mantle source, 1 % slab-derived melts and 2 % slab-derived fluids were incorporated; conversely, for the Erhongwa mantle source, approximately 2.5 % slab-derived melts and 0.5 % slab-derived fluids were added. Parental magmas of the Erhongwa intrusion exhibit higher oxygen fugacity and water contents than those of the Huangshandong intrusion. Specifically, the magma of the Erhongwa intrusion undergoes magma evolution within a shallow magma chamber, whereas the magma of the Huangshandong intrusion gains sulfide saturation within a deep magma chamber. This research suggests that factors including mantle source features, suitable timing for sulfide separation, and depth of magma chamber are essential for Ni-Cu sulfide mineralization in mafic-ultramafic intrusions in convergent margin setting. [ABSTRACT FROM AUTHOR]

Magmatic sulfide ores from the western and eastern intrusions of the world's third-largest Jinchuan Ni–Cu deposit are separated into disseminated, net-textured, and massive sulfides, or Fe-rich, transitional, Cu-rich ores. However, the composition of base metal sulfide (BMS) minerals from each intrusion and ore type still lacks investigation. By comparing the variations of chalcophile element composition of BMS minerals from different intrusions, sulfide textures, and ore types, new discriminant diagrams are constructed for subsequent exploration. BMS minerals from the eastern intrusion host more slightly chalcophile elements (Zn As, Sn Cd) because of the higher degree of crustal contamination, and less strongly chalcophile elements (Co, Bi, Se, Re, Ag, Te) due to the lower amount of prior sulfide segregation. R-factor modeling indicates that disseminated sulfides are formed at the highest R-factors, while massive sulfides are formed at the lowest. Correspondingly, R-factor upgrading results in higher concentrations of Se and Ag in BMS minerals from disseminated sulfides compared to net-textured sulfides. Most chalcophile elements in BMS minerals show positive or negative correlations with whole-rock Cu/Ni c ratios (Ni c represents corrected whole-rock Ni content after deducting Ni in olivine), suggesting extensive chalcophile element fractionation occurred during progressive sulfide fractionation. Furthermore, the elements that are slightly to moderately incompatible with monosulfide solid solution (MSS) while predominately hosted by BMS minerals (e.g., Cd, Se, Ag, and Te in chalcopyrite) show better correlations, making them preferable for tracing the sulfide fractionation. Utilizing the partial least squares-discriminant analysis models, we propose plots of Cd/(Co + As) vs. Bi/(Co + As), Ag vs. Bi/(Ag + Cd), and Co/(Ag + Cd) vs. Bi/(Ag + Cd) to discriminate chalcopyrite from different intrusions, sulfide textures, and ore types, respectively. Additionally, the occurrence of chalcopyrite with increased Bi/(Ag + Cd) and Co/(Ag + Cd) ratios and decreased Ag content presents promising clues for exploring Fe-rich massive sulfide ores. [Display omitted] • Variations of BMS compositions from different intrusions and types are clarified. • Compared the potential of each BMS as indicator minerals for exploration • Effective diagrams for discriminating various types of chalcopyrite are built. [ABSTRACT FROM AUTHOR]

Wolframite-quartz vein-type W deposits commonly produce wolframite accompanied by variable amounts of sulfides with industrial value. In such deposits, the characteristics of sulfide-forming fluids and precipitation mechanisms are poorly understood. Dajishan, located in the east of the Nanling metallogenic belt, is a giant W-polymetallic deposit with the total reserve of 190,000 t WO 3 , 6253 t Bi, and 1199 t Mo. Individual ore vein at Dajishan has been divided into three hydrothermal stages according to mineral paragenesis: wolframite-quartz stage, scheelite-sulfide stage, and fluorite-calcite stage. Except for molybdenite which occurs in the wolframite-quartz stage, most sulfides occur in the scheelite-sulfide stage and consist of pyrrhotite, bismuthinite, cosalite, chalcopyrite, sphalerite, and galena. Typical quartz samples coexisting with both wolframite and sulfides from the No. 23 vein in 417 m level were studied in detail to rebuild the hydrothermal history of the first two mineralization stages. While the studied quartz is paragenetically later than coexisting wolframite and likely molybdenite, SEM-CL reveals two quartz generations in which precipitation of other sulfides is intimately associated with the later generation. One type of primary fluid inclusions (type L Q1) and two types of pseudosecondary fluid inclusions (types V Q2 and L Q2) forming immiscible assemblage are identified in the first (Qz1) and second (Qz2) quartz generations, respectively. Microthermometry and chemical composition data of quartz-hosted fluid inclusion were measured in combination with previously reported data from wolframite-hosted fluid inclusions to quantitatively determine the fluid evolution during ore formation. Fluid major and trace element signature shows clear inheritance of sulfide precipitating fluid from early wolframite mineralizing fluid. Early molybdenite precipitation (61.2–142.8 ppm drop to 5.6–6.2 ppm) is accompanied by mixing of meteoric water into W unloaded early magmatic fluid whose pH was buffered by fluid-rock interaction. As bracketed by type L Q1 and L Q2 inclusions, deposition of late Bi, Cu, Zn, and Pb sulfides is primarily controlled by fluid immiscibility and the induced drop of fluid temperature and acidity. [Display omitted] • SEM-CL reveals detailed mineralization sequence of sulfides in wolframite-quartz veins at Dajishan. • Ore-forming fluids in different stages are dominated by magmatic fluids. • Fluid cooling and fluid immiscibility are the key factors triggering sulfide precipitation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Au, Ag, Te in pyrite of the auriferous veins occur in micron-sized mineral inclusions. • Te melt is a key scavenger of Au from ore-forming fluids in the Yangwuchang deposit. • The ore-forming metals should be derived from a W-Au-rich magma system. • It has great W exploration potential at the deep part of magmatic type Au deposits. The co-mineralization of W and Au in some deposits has long been noted, yet remains debated. The Yangwuchang W-Au deposit provides an excellent opportunity for examining the genetic relationship between the mineralization of these two elements. In this paper, we present new trace elemental data for pyrite and sulfur isotopic compositions for sulfide minerals to better understand the co-mineralization of W and Au. Type 1 pyrite (Py1) is mainly hosted in the W-bearing veins and has low concentrations of Au (0.01–0.04 ppm), Ag (0.06–437 ppm), and Te (1.77–234 ppm). In contrast, type 2 Pyrite (Py2) in the auriferous veins is relatively enriched in Au (0.06–209 ppm), Ag (0.44–58610 ppm), Te (1.88–42337 ppm), and other trace elements. The concentration of Au has a positive relationship with Te but not with As, suggesting Te melt plays a significant role in scavenging Au from ore-forming fluids during mineralization. The narrow range of δ34S value (-3.17 to 3.69 ‰), combined with high Te contents and Co/Ni ratios of pyrite, indicates that the ore-forming metals may have been derived from a W-Au-rich magma. The slight negative values of δ34S in Py1 infer the localized pressure fluctuations during W mineralization. We concluded the W and Au could be both derived from one single magma system. The deep part of Au-bearing veins has great exploration potential for W mineralization. [ABSTRACT FROM AUTHOR]

• Five recycling processes for used lithium iron phosphate cathodes are compared. • Indirect emissions are included in environmental impact assessments of recycling. • The acid-free extraction process is generally the most recommended currently. • Potential performance changes are projected based on trends in China's energy mix. Recycling end-of-life lithium iron phosphate (LFP) batteries are critical to mitigating pollution and recouping valuable resources. It remains imperative to determine the most eco-friendly and cost-effective process. This article presents a comprehensive assessment of two domestic hydrometallurgical and three laboratory-level recycling processes for end-of-life LFP battery cathode materials. The environmental impacts across six categories, including climate change, human toxicity and carcinogenicity, abiotic resource depletion, acidification, eutrophication, and photochemical oxidation, are assessed using CML-IA baseline method, and the economic performance is analyzed based on 2022 material and energy prices. Results indicate that: 1) Acid-free extraction exhibits the lowest environmental impacts, while those of acid-leach precipitation and sulfide roasting are relatively high; 2) Laboratory-level processes with lower direct emissions, including wastewater, waste gas, and solid waste, consider that indirect emissions may lead to larger environmental impacts; 3) Economically, acid-leach distillation is the most profitable. Currently, acid-free extraction is generally the most recommended. With the optimization of energy structure in China, the environmental performance of sulfide roasting should be greatly improved. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Confirmed shared hydrothermal fluid source for skarn and quartz-vein orebodies. • Identified physicochemical condition differences between two orebodies. • Recognized fluid-rock reactions for skarn; cooling/mixing for quartz vein. • Proposed multi-stage metallogenic model for skarn and vein-type deposits. The Tongshanling Cu–Pb–Zn deposit, situated within the Qin-Hang intra-continental porphyry-skarn metallogenic belt in South China, presents a valuable case study of intrusion-related ore systems. This deposit is characterized by skarn mineralization closely associated with subsequent quartz-vein sulfide mineralization. While considerable research has been devoted to understanding the origin and evolution of the intrusions and mineralization processes, limited attention has been given to elucidating the relationship between the skarn and quartz-vein mineralization, along with the physicochemical conditions governing their formation. Here, we conducted a comprehensive mineralogical and isotopic investigation of sulfides, and a thorough analysis of fluid inclusion assemblages. We aimed to discern disparities in the sources of ore-forming materials, formation temperature, sulfide fugacity, and precipitation-alteration mechanisms of hydrothermal fluids for these two distinct orebodies. Although same sulfide species including arsenopyrite, pyrite, chalcopyrite, and sphalerite, some silicate minerals such as garnet, chlorite, and epidote are exclusive to the skarn orebodies and absent in the quartz veins. The homogeneous temperatures of fluid inclusions in the skarn orebody, ranging from the early to late stages of evolution, decrease from ∼310 to ∼290 °C. Simultaneously, salinity varies from 5.5 to 3.1 wt% NaCl eqv. In the quartz vein mineral body, the temperature reduction is more pronounced, decreasing from ∼270 to 186 °C, with salinity ranging from 3.6 to 1.4 wt% NaCl eqv. Sphalerite geothermometer indicates that peak hydrothermal fluid temperature in the skarn orebodies (∼300–340 °C) was relatively higher than that in the quartz-vein orebodies (<300 °C). Nevertheless, temperatures in both hydrothermal fluid systems declined as mineral precipitation proceeded, corresponding to a decrease in sulfur fugacity. The final stage of sphalerite represents the lowest temperature, salinity and sulfur fugacity with associated quartz displaying the lowest salinity across the entire hydrothermal fluid spectrum at the Tongshanling deposit, suggestive of meteoric water incorporation. This study delves into the multifaceted history of mineralization at the Tongshanling deposit, providing a fresh perspective on the origin and evolutionary relationships of Cu-polymetallic deposits associated with intrusions, particularly those involving multiple stages of mineralization in skarns and quartz veins, contributing to a better understanding of similar deposits worldwide. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three generations of pyrite and quartz are identified in the Meiling deposit. • Lithium and Al compositions may control the CL intensity of Meiling quartz. • Pyrite Co/Ni ratio indicates a hydrothermal origin. • Abundant porous pyrite and trace element ratios indicates that boiling plays an important role in the metal precipitation. • Multistage sulfides and quartz compositions can effectively reconstruct hydrothermal fluid evolution process in the Meiling deposit. The Meiling is a newly discovered Late Paleozoic epithermal Cu–Zn–Au deposit in the Kalatag arc, East Tianshan, NW China. Some key issues such as metal substitution mechanisms, physicochemical characteristics of ore-forming fluids and sulfide precipitation process are still unclear. In this contribution, we carried out a detailed trace element geochemistry of sulfides and quartz and in-situ sulfur isotopic compositions to characterize the ore-forming elements enrichment process. The ore-forming process can be divided into four stages, including quartz–pyrite, quartz–chalcopyrite–pyrite, quartz–chalcopyrite–sphalerite–pyrite and quartz–calcite–pyrite stage, respectively. Three generations of pyrite are identified in the Meiling deposit, including subhedral to anhedral pyrite (Py1), fine-grained pyrite (Py2) and irregular pyrite (Py3). Three generations of hydrothermal quartz (Qtz1, Qtz2, and Qtz3) are identified. Titanium, Al and Li compositions of Qtz1 are mostly higher than those of Qtz2 and Qtz3, indicating a higher formation pressure and temperature. Average Li compositions show a decreasing trend from Qtz1 to Qtz3, namely 42.8 ppm, 11.3 ppm, 5.3 ppm, respectively. Similar trends also appear in the Al compositions, indicating that the Li and Al compositions may control the CL intensity of quartz. The increasing pH from Qtz1 to Qtz3, combined with the alteration characteristic and the sequence of sulfide precipitation, indicating a clear relationship between pH and mineralization process in the Meiling deposit. LA–ICP–MS data shows that Py1 displays the highest compositions of Te (avg. 44.66 ppm) and Pb (avg. 361.95 ppm). Py2 contains the highest compositions of Cu (avg. 5643.85 ppm), Zn (avg. 436.72 ppm), As (avg. 15300.55 ppm), and Ag (avg. 146.70 ppm), whereas the Py3 contains the most Se (avg. 405.40 ppm), Au (avg. 18.65 ppm), Ni (avg. 19.45 ppm) and Co (avg. 12.64 ppm) compositions. In Py2, the high compositions of Cu and Pb may be due to the existence of inclusions in chalcopyrite and galena. Chalcopyrite is enriched in Ag, Te, Sb, Zn, Cd, In and Se and poor in Ge, Au and Bi. Sphalerite is characterized by high compositions of Ag, Cd, Fe, Mo, Cu, Ga and Sb. Cobalt/Ni ratios of Py1(avg. 1.7), Py2 (avg. 4.9), and Py3 (avg. 1.8), indicating a hydrothermal origin. Sulfur isotopic compositions of sulfides suggest that quartz porphyry is an important material source at Meiling deposit. Tellurium composition in Py1 (avg. 44.7 ppm) was significantly higher than that in Py2 (avg. 1.10 ppm) and Py3 (avg. 0.90 ppm), indicating that the fluid f O 2 in stage II and III was higher than that in stage I. Moreover, stage II and III have nearly the same f O 2 values. Arsenic enters pyrite in the form of As– instead of S– in the Meiling deposit, causing its lattice defects to promote Au+ to enter into pyrite. Au-As-rich Py3 and visible gold are most likely to be formed by direct precipitation from the new Au-As rich ore-forming fluid. Abundant porous pyrite and trace element ratios (e.g., Ag/As, Ag/Co) indicates that boiling plays an important role in the precipitation process of Py2 and Py3. In summary, trace element compositions of multistage sulfide and quartz can effectively reconstruct hydrothermal fluid evolution and metal enrichment process of Meiling epithermal Cu–Zn–Au mineralization system. [ABSTRACT FROM AUTHOR]

Large-scale gold mineralization during the Early Cretaceous is identified in the Jiaodong Peninsula of China. Sources of ore-forming fluids remain debated. We study the Qilishan gold deposit in the northwestern Jiaodong Peninsula with detailed mineralogical observation and in-situ sulfur isotope analyses, in order to reveal the gold occurrence and the origin of ore-forming fluids. The Qilishan gold deposit is mainly clastic altered rock-type in mineralization, and ore minerals are visible native gold, electrum, pyrite, chalcopyrite and galena, gangue minerals as quartz, sericite and calcite. The gold occurrence includes inclusion and intergranular types, formed within pyrites and chalcopyrites and along their fissures. In-situ sulfur isotope analysis of gold-bearing sulfides suggests that the Qilishan deposit is enriched in heavy sulfur, with δ34S values mainly from +8.0‰ to +12.0‰. δ34S values increase gradually with the fluid evolution from the early to late stages, which is interpreted to be related to the loss of sulfur via sulfide precipitation. The crystallization of sulfides from hydrothermal fluids may have triggered the instability of Au(HS)2, and finally led to gold precipitation. Combined with sulfur isotope compositions of other gold deposits (n=43) and wall-rocks in the Jiaodong Peninsula, it is proposed that the ore-forming fluids were probably not directly originated from metamorphic wall-rocks (e.g., Jiaodong Group). Moreover, the relatively long time interval rules out the possibility that the gold mineralization (ca. 120 Ma) was associated with granitic magma activities (mostly 160–150 Ma). Possible ore genesis scenario is that, long-term subduction of slabs (e.g., the Paleo-Pacific) with gold-enriched pyritic materials and crustal sedimentary rocks resulted in both high Au contents and positive δ34S values of sulfur in the lithospheric mantle below the North China Craton. Subsequently, devolatilization of the metasomatized mantle produced auriferous fluids that migrated upward along translithospheric fault systems, and gold finally precipitated in favorable structural positions, generating the world-class Jiaodong deposits in the Early Cretaceous. [ABSTRACT FROM AUTHOR]

Background: Pharmacogenomics is a facet of personalized medicine that explores how genetic variants affect drug metabolism and adverse drug reactions. Therefore, this study aims to detect distinct pharmacogenomic variations among the Jingpo population and explore their clinical correlation with drug metabolism and toxicity., Methods: Agena MassARRAY Assay was used to genotype 57 VIP variants in 28 genes from 159 unrelated Jingpo participants. Subsequently, the chi-squared test and Bonferroni's statistical tests were utilized to conduct a comparative analysis of genotypes and allele frequencies between the Jingpo population and the other 26 populations from the 1000 Genome Project., Results: We discovered that the KHV (Kinh in Ho ChiMinh City, Vietnam), CHS (Southern Han Chi-nese, China) and JPT (Japanese in Tokyo, Japan) exhibited the smallest differences from the Jingpo with only 4 variants, while ESN (Esan in Nigeria) exhibited the largest differences with 30 variants. Besides, a total of six considerably different loci (rs4291 in ACE, rs20417 in PTGS2, rs1801280 and rs1799929 in NAT2, rs2115819 in ALOX5, rs1065852 in CYP2D6, p < 3.37 × 10 -5 ) were identified in this study. According to PharmGKB, rs20417 (PTGS2), rs4291 (ACE), rs2115819 (ALOX5) and rs1065852 (CYP2D6) were found to be associated with the metabolism efficiency of non-steroidal anti-inflammatory drugs (NSAIDs), aspirin, montelukast and tamoxifen, respectively. Meanwhile, rs1801280 and rs1799929 (NAT2) were found to be related to drug poisoning with slow acetylation., Conclusion: Our study unveils distinct pharmacogenomic variants in the Jingpo population and discovers their association with the metabolic efficiency of NSAIDs, montelukast, and tamoxifen., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study employed knowledge graph technology to analyze the research status and hot spots of Realgar and provide guidance for clinical application and further research of this drug. The research articles both in English and Chinese involving Realgar were retrieved from five databases including CNKI, Wanfang, VIP, SinoMed, and Web of Science. And NoteExpress, a literature management software was used to screen literature. CiteSpace was utilized for visualized analysis and presentations of the authors, institutions, and keywords. 2 879 articles in Chinese and 194 articles in English were included. China Journal of Chinese Materia Medica and Journal of Ethnopharmacology were the top Chinese and English journals in terms of publication volume. Realgar is widely used in the treatment of skin diseases, blood diseases, and cancer. JIANG Hong was the author who have published more articles in Chinese and English working with teams. School of Public Health of China Medical University and China Academy of Chinese Medical Sciences published the most articles in Chinese and English. The research on Realgar mainly focuses on clinical application, mechanism of action, reduction of toxicity, and enhancement of efficacy. The authors and institutions of Realgar research are mainly concentrated in China. The study on the mechanism of treating hematological diseases and cancer with Realgar, as well as the research on its effects of reducing toxicity and enhancing efficacy, are the current research hotspots. The mechanism of &quot;same treatment for different diseases&quot; in Realgar needs to be further explored. It is urgent to carry out interdisciplinary research on Realgar. This study can provide a refe-rence for the clinical application of Realgar and provide ideas for further research on Realgar.

Ecological pollution caused by heavy metals released from sediments is a worldwide concern. However, the effect of changes in sediment speciation on their release of heavy metals has not been adequately reported. In this study, the research focused on Pb and Cr in the ice period of Wuliangsuhai. This study analyzed changes in the sediment speciation of Pb and Cr before and after a release experiment using four risk assessment methods while varying the temperature, pH, and salinity of the water column. The results indicated that the total concentration of Pb ranged from 11.17 to 24.25 mg/kg, while for Cr it ranged from 42.26 to 69.68 mg/kg. Both elements exhibited mild contamination. The release of Pb and Cr from sediments increases with increasing water temperature, mainly due to the conversion of the residual fraction of Pb to the Fe-Mn oxide fraction and Cr converting more residual fraction to the organic matter and sulfide fraction. The release of sediment Pb and Cr decreased with increasing pH, with Pb converting more acid extractable fraction to the residual fraction and Cr converting more organic matter and sulfide fraction to the residual fraction. In contrast, the release of Pb and Cr increased and then decreased with increasing salinity. For Pb, the acid extractable fraction was more susceptible to conversion to the residual fraction by environmental influences, whereas for Cr, the organic matter and sulfide fraction were susceptible to conversion to the residual fraction., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Urbanization involving the excavation and reuse of arsenic-bearing geological materials may pose human health risks. We investigated the distribution and sources of soil arsenic at a coastal reclamation site in the Pearl River Delta, China, and proposed risk management strategies. Analysis of 899 soil samples revealed an average of 58.97 mg/kg arsenic, with a maximum of 1450 mg/kg, mainly in fill material obtained from a local island. Integrative analysis combining reclamation history, regional geology, and bedrock mineralogy conclusively identified hydrothermally altered arsenic-bearing sulfide minerals within extensively fractured bedrock as the primary source of arsenic. Physical weathering and anthropogenic rock blasting produced discrete arsenic-rich particles that were directly transported into soils during land reclamation and accumulated to potential hazardous levels. Oral, dermal, and inhalation pathways were identified as primary exposures for future populations. Integrated engineering and institutional controls, coupled with long-term monitoring, were recommended to mitigate risks. The results highlight the importance of identifying specific geogenic and anthropogenic sources that contribute to heavy metal enrichment of soils in reclaimed areas where native bedrock naturally contains elevated level of metals, supporting evidence-based best practices for risk management and future land use., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The fate of riverine sulfate ion (SO 4 2- ) and its environmental effects in arid environment are difficult to evaluate due to its complicated sources and strongly coupled behaviors with water cycle which is significantly modified by humans. To understand the sulfur cycle in aquatic systems in arid environment, the chemical and sulfur and oxygen isotopic compositions (δ 34 S SO4 and δ 18 ) of major rivers around the Badain Jaran Desert, northwestern China, were investigated. These rivers had averaged SO SO4 ) of major rivers around the Badain Jaran Desert, northwestern China, were investigated. These rivers had averaged SO 4 2- content at 1336 µmol/L, over 10 times higher than the global average. The δ 34 S SO4 and δ 18 O SO4 values ranged from -5.3‰ to +11.8‰ and +1.6‰ to +12.8‰, respectively. The end-member analysis and the inverse model showed that riverine sulfate was mainly derived from evaporites dissolution (0-87%), sulfide oxidation (13%-100%) and precipitation (0-33%), indicating heterogeneity in sulfur sources and behaviors along the river drainage with the lithology variations and climate gradients. Multiple isotopic tools combining with hydro-chemistry compositions could be applied to reveal sulfur cycle in arid environment. Based on the calculation, sulfide oxidation plays the primary role in the headwater and upstream in the Qilian-Mountains area, where sulfide is widely exposed. While the proportion of evaporites dissolution contributing to riverine sulfate is much higher in downstream in a drier environment. Besides, less precipitation and higher temperature can lead to more intensive evaporation, affecting the process of sulfide oxidation and enhancing the rates of evaporites dissolution and sulfate precipitation in the basin., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2023. Published by Elsevier B.V.)

Colloform pyrite (CPy) is widely distributed in the Tongling mineralization cluster of the Middle–Lower Yangtze River Mineralization Belt (MLYRMB), China. There have many debates as to whether such CPy is associated with Late Mesozoic igneous or Carboniferous sedimentation. CPy from the Xinqiao deposit, a representative of the stratabound sulfide deposits in the MLYRMB, was studied by powder X‐ray diffraction (XRD), field‐emission scanning electron microscopy (SEM), and high‐resolution transmission electron microscopy (TEM). The results show that CPy mainly comprises pyrite, pyrrhotite, quartz, and illite. Pyrite in CPy shows cubic, globule, and xenomorphic morphologies. No octahedral or pyritohedron was observed. Most of the quartz crystals display xenomorphic morphology, where pyrite mold are popular on the surface. Organic matter (OM), which is usually bound to illite, is an important component in CPy. Morphological investigations which exhibit detrital features of quartz and clay minerals indicate that they were derived from continental weathering. Specially, some hexagonal pyrrhotite nanoparticles which show mackinawite morphology are coexisted with OM. The results indicate that the transformation process of sulfides possibly is mackinawite (the precursor) —hexagonal pyrrhotite—pyrite. Thus, compositional and micro‐textural characteristics of CPy in Xinqiao deposit suggest it to be a sedimentary origin rather than a hydrothermal origin which is associated with Yanshanian magmatism. Moreover, the coexistence of CPy and stratabound sulfide orebodies in the MLYRMB suggests a causal link between the two. It is considered that CPy might have served as a Cu mineralization geochemical barrier for the Cu‐bearing ore‐forming fluids, which originated from the Mesozoic magma in the MLYRMB. [ABSTRACT FROM AUTHOR]

The Xiaorequanzi Cu–Zn deposit is in the westernmost part of East Tianshan Terrane in northwestern China. The deposit is unique in the region being a volcanogenic massive sulphide (VMS) deposit located near a zone (or belt) containing giant late Paleozoic porphyry Cu deposits. Aiming to better understand the genesis of the mineral deposits in the terrane and their tectonic setting, we report our findings of detailed studies on fluid inclusion microthermometry, Re–Os dating of chalcopyrite from the massive ore, and U–Pb dating of zircons from the host volcanic rocks. There are two sulphide stages with early pyrite succeeded by chalcopyrite–sphalerite, which are hydrothermally overprinted and supergene enriched. The hydrothermal overprinting is characterised by quartz–sulphide veins crossed by carbonate-rich quartz veins. Quartz from the chalcopyrite–sphalerite stage is characterised by primary fluid inclusions containing H2O–NaCl(–CO2) and homogenise at 228–392 °C with a salinity of 2.2–13.3 wt.% NaCl equiv. Secondary fluid inclusions related to the hydrothermal overprinting homogenise at 170–205 °C with a salinity of 2.7–12.1 wt.% NaCl equiv. Fluid inclusions in the quartz–sulphide stage of the hydrothermal overprinting contain H2O–NaCl with homogenisation temperatures of 164–281 °C and salinities in ranging from 2.9 to 12.4 wt.% NaCl equiv. Fluid inclusion in the quartz–calcite stage contain H2O–NaCl with homogenisation temperatures of 122–204 °C with salinities of 1.4–12.4 wt.% NaCl equiv. These characteristics are like those of the secondary fluid inclusions in the VMS mineralisation. Combining these findings with H–O isotopic data from previous studies, we propose that the primary mineralising fluid is magmatic in origin. Tuff hosting the mineralisation yields a SHRIMP U–Pb zircon age of 352 ± 5 Ma, which is interpreted as the age of the tuff, and a porphyritic felsite dyke intruding the tuff yields a SHRIMP U–Pb zircon date of 345 ± 6 Ma, interpreted as the emplacement age of the dyke. Chalcopyrite from the main orebody at Xiaorequanzi yields a Re–Os isochron age of 336 ± 13 Ma with an initial 187Os/188Os ratio of 0.25 ± 0.55 (MSWD = 12). Given that the VMS deposit is a syngenetic deposit, we regard the upper ca. 349 Ma limit of the Re–Os date as the approximate age of the chalcopyrite. The three dates are the same within error, and the upper limit of the Re–Os date of ca. 349 is taken as the age of the volcanic, dyke, and mineralisation. The volcanic rocks around the Xiaorequanzi deposit have been previously classified as calc–alkaline to high-K calc–alkaline enriched in large-ion lithophile elements and depleted in high-field-strength elements, which are characteristics indicative of a forearc setting. It is suggested that VMS mineralisation formed in a forearc setting related to the north-directed subduction of the Palaeo-Kangguer or North Tianshan oceanic plates. [ABSTRACT FROM AUTHOR]

Long‐stamen chive (Allium macrostemon Bunge; AMB), which is prevalent in the Wuling Mountain area of China, is a characteristic food of the nation. In the study, we evaluated the as‐yet‐unknown nutritional value and antioxidant activity of fresh AMB. The free amino acid content, volatile components, and free radical‐scavenging capacity of isolated organic sulfides were analyzed to evaluate the qualitative and physiological properties of fresh AMB. The plant was found to be rich in free essential amino acids and contain multiple flavor‐imparting amino acids. The organic sulfides showed an apparent free radical‐scavenging activity in vitro. Furthermore, these sulfides alleviated oxidative stress in Caenorhabditis elegans. Notably, the organic sulfides isolated from AMB enhanced the activities of superoxide dismutase, catalase, and glutathione peroxidase; improved motility; and extended the lifespan in oxidative stress‐affected nematodes. In conclusion, our study indicates that AMB is a nutritious vegetable with potential to be developed as a functional food. Practical applications: Long‐stamen chive is a wild edible vegetable belonging to the genus Allium (A. macrostemon Bunge; AMB). However, its quality and physiological properties have not been comprehensively investigated. Herein, we analyzed the free amino acid content, composition of volatile compounds, and potential antioxidative properties of AMB. Our results indicated that AMB is rich in essential amino acids, making it a highly nutritious food. Further analysis indicated that AMB contains a high proportion of organic sulfides, which have been previously been shown to have antioxidative properties. Together, our findings indicate that AMB contains important bioactive components and can be developed as a functional food or health supplement. Furthermore, our findings will enhance public awareness regarding this wild resource and provide new directions for the research and development of natural products derived from it. [ABSTRACT FROM AUTHOR]

Baogutu is a large gold deposit (4 Mt @ 5.5 g/t Au) in West Junggar, NW China. We conducted a Re‐Os geochronological study on seven pyrite samples from auriferous quartz‐pyrite veins, which yielded a Re‐Os isochron age of 312 ± 11 Ma (2σ). This age defines the timing of gold mineralization, and overlaps the emplacement age of diorite to granodiorite porphyry stocks (319–310 Ma) in the Baogutu district. The Os initial ratio of 0.46 ± 0.21 (2σ) suggests a mix of components from both mantle and continental crust in the ore‐forming system, which is similar to the proposed magma source of porphyry stocks. The δ34S values of sulphide minerals vary in a narrow range from +0.1 to −3.3‰, indicating that the sulphur is likely of igneous origin. Our data suggest that the Baogutu gold mineralization is probably genetically linked to the regional diorite to granodiorite magmatism. The new data provide important constraints for an evolving genetic model of the Baogutu gold deposit. [ABSTRACT FROM AUTHOR]

The Xiarihamu Cu–Ni sulfide deposit is the second-largest Cu–Ni deposit in China, located in the Eastern Kunlun orogenic belt. However, despite previous study, the formation and evolution of this deposit remains a key unknown in the tectonic evolution of the Eastern Kunlun Orogenic Belt. Moreover, the petrogenesis of the ore-bearing rocks and the nature of ore genesis are the subjects of ongoing debate. Here, we present detailed field observations, petrology, zircon U–Pb geochronology, and Re–Os isotopic analyses to constrain the timing and genesis of the Xiarihamu Cu–Ni sulfide deposit. Sulfides from the massive ores yielded a Re–Os isotopic isochron age of 408 ± 11 Ma. Four samples from the ore-bearing Xiarihamu mafic–ultramafic intrusions yielded zircon U–Pb ages of 423.1 ± 2 Ma, 422.9 ± 3.1 Ma, 422.7 ± 2.3 Ma, and 422.6 ± 2.7 Ma, respectively, indicating that the ore formed during the Silurian. The calculated initial 187Os/188Os ratio and γOs values ranged from 0.5109 to 0.8499 and from 311 to 584, respectively, indicating that crustal contamination played an extremely important role in triggering sulfide saturation. In combination with previous research, drill core observations and Re–Os data provide robust evidence for multiple pulses of magma replenishment throughout the process of ore genesis. Based on this evidence, the large-scale magmatic Cu–Ni mineralization in Xiarihamu likely occurred in a post-collisional setting related to tectonic slab breakoff. [ABSTRACT FROM AUTHOR]

• All of these volcanic rocks are depleted in PGEs (0.02–0.40 ppb). • Magmas reached sulfide saturation before they evolved to compositions with 7 wt.% MgO. • Sulfides were removed from the magma, extracting most of the Au and Cu from the magma. • Release of metal to the fluids from sulfides accounts for the budget of giant deposit. It is widely considered that arc magmas are highly oxidized, and can thus dissolve a large amount of sulfur, thereby preventing significant sulfide saturation prior to fluid saturation. Therefore, chalcophile metals (e.g., Cu and Au) are retained in the magma and finally extracted by exsolved hydrothermal fluids. To test this hypothesis, we analyzed the abundances of platinum-group elements (PGEs) in a suite of arc volcanic rocks, which are the extrusive counterparts of magmas associated with the world-class Zijinshan porphyry–epithermal Cu–Au ore district in SE China. All of these volcanic rocks are depleted in PGEs (e.g., Pd = 0.02–0.40 ppb) in comparison with fertile arc magmas, and the PGE contents decrease with decreasing MgO from basalt to dacite. The results show that the parental magmas for these rocks reached sulfide saturation before they evolved to 7 wt.% MgO, which is earlier than the onset of magnetite crystallization. Sulfide liquid and monosulfide solid solution (MSS) were removed from the magma before it evolved into a dacitic composition. This process extracted most of the Au and Cu from the magma. Modeling results indicate that Au concentrations would not exceed 7–10 times the Pd concentrations in the residual silicate magma, irrespective of the partition coefficients between the sulfide and silicate melt. Given the low Pd contents in dacitic arc magmas worldwide, depletion of Au and Cu might be a common feature of highly evolved arc magmas. Thus, the hydrothermal ore fluids separated from such evolved arc magmas would not contain enough metals to form the giant Zijinshan porphyry–epithermal Cu–Au ore district. We propose a model in which the magmas parental to the arc volcanic rocks achieved S saturation, and thus large amounts of sulfides accumulated in the underlying magma chamber before the magmas were extruded from depth to the surface. During solidification of the magma chamber, these deposits formed from exsolved magmatic hydrothermal fluids that dissolved abundant pre-existing magmatic Cu–Au-rich sulfide assemblages. Release of large amounts of Au, Cu and S to the ore-forming aqueous fluids by dissolution of sulfides can account for the metal and S budgets of giant porphyry–epithermal Cu–Au deposits. [ABSTRACT FROM AUTHOR]