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The Jinding deposit, located in the northern part of Lanping basin in southwest China, is the second largest Zn-Pb deposit in China and the third largest Mississippi Valley-type deposit identified globally. The deposit consists of several large tabular orebodies within the Jinding dome. Two stages of sulfide mineralization (sphalerite, galena, and pyrite) are identified, which are mainly hosted in the siliciclastic strata of Early Cretaceous and Paleocene age. The early sulfide minerals are mostly fine grained ( The δ34S values, ranging from –30 to –10‰ for the fine-grained and disseminated sulfide minerals and from –24.50 to –16.27‰ for the solid bitumen in the early (main) mineralization stage, suggest that H2S was generated by microbial sulfate reduction. We propose that this occurred in the Triassic strata prior to or during migration of hydrocarbons to the Jinding dome to form a H2S-enriched paleo-oil reservoir. This hypothesis is supported by the similarity of the δ34S values (–27.62 to –17.38‰) of solid bitumen in the Sanhedong Formation (the source rocks) to that of bitumen in the ores. The late-ore sulfide, however, displays significantly higher δ34S values, ranging from –8 to 0‰. We propose that the H2S of this stage was mainly generated by thermochemical sulfate reduction as a result of the interaction between hydrocarbons, sulfate, and hydrothermal fluid. The hydrocarbons were oxidized into bitumen that has δ34S values from –7.38 to –4.61‰.

The genesis of the giant Ag-Cu-Pb-Zn polymetallic mineralization in the northern Lanping basin, Southwest China, remains controversial. To address the sources of metals, a systematic study on Hg isotope compositions was conducted for the Cu-dominated deposit at Baiyangping and the Pb-Zn-dominated deposits at Fulongchang and Liziping. The Cu deposit shows positive Δ199Hg signatures (0.14 ± 0.13‰), in contrast to the Δ199Hg of the Pb-Zn deposits (− 0.09 ± 0.06‰). As positive Δ199Hg values are commonly observed in marine sediments and the Lanping Triassic marine sedimentary rocks show exclusively positive Δ199Hg signals (0.03 ± 0.07‰), the Hg in Cu ores was mainly sourced from the Triassic strata. The negative Δ199Hg signals observed in the Pb-Zn deposits, typical of terrestrial Hg, agree roughly with those of the Jurassic to Paleocene terrestrial sedimentary rocks (− 0.05 ± 0.08 ‰), indicating that the terrestrial strata provided the Hg in Pb-Zn ores. Compared to the source rocks, the Cu deposit shows isotopically lighter Hg enrichments (δ202Hg = − 2.30 ± 0.35‰), possibly resulting from fractionations induced by Hg2+ sorption, organic complexation, and precipitation of Hg-bearing sulfides. The Pb-Zn deposits show comparable or slightly heavier δ202Hg (− 0.56 ± 0.48‰); moreover, δ202Hg values of late-stage sulfides are higher than early-stage δ202Hg values, suggesting that the δ202Hg variation was primarily caused by sulfide precipitation. Thus, Hg isotope data indicate that separate hydrothermal events resulted in Cu and Pb-Zn mineralization. More importantly, this study reveals the great potential of Hg isotopes to discriminate sedimentary sources of metals for low-temperature hydrothermal deposits.

Extremely thick Fe-Ti-V oxide layers are hosted in mafic-ultramafic intrusions of the Emeishan large igneous province (LIP) in the Pan-Xi district of southwest China, accounting for a quarter of the world’s Ti and V resource. It is unclear why these small intrusions contain such huge ore reserves that form world-class Fe-Ti-V oxide deposits. We find that the Hongge intrusion contains 35% Fe-Ti-V oxides, which is twice the typical content in mafic-ultramafic intrusions worldwide and the experimentally determined cotectic proportion in natural ferrobasaltic magma systems. The V content is almost constant in titanomagnetite across the entire Hongge intrusion in the Emeishan LIP, indicating a small (10–20%) proportion of cotectic Fe-Ti-V oxide during fractional crystallization. The bulk composition of the intrusion indicates an open magma system at the time of its formation. Clinopyroxene phenocrysts from overlying basalts contain Fe-Ti-V oxide inclusions, indicating that the phenocrysts crystallized at depth from magma saturated in Fe-Ti-V oxide and were then transported to the surface. We suggest that these intrusions were feeder conduits to the overlying basalts, where the silicates were cotectic with Fe-Ti-V oxides which were then extracted from the underlying intrusion as phenocrysts. Such a fundamental process is key to increase the proportion of oxide minerals in the residual assemblage, thereby upgrading the barren oxide-bearing rocks to world-class Fe-Ti-V oxide deposits in the small intrusions of the Emeishan LIP. A similar process might have occurred in LIPs elsewhere, meaning that intrusions formed as conduit-like open systems to the basalts in LIPs are good exploration targets for giant high-grade Fe-Ti-V oxide deposits.

The Baiyangping Cu–Ag polymetallic ore district is located in the northern part of the Lanping-Simao foreland fold belt, between the Jinshajiang-Ailaoshan and Lancangjiang faults, and the deposit can be divided into eastern and western ore zones. Based upon microscope observation of ore minerals and analysis of zinc, copper, and strontium isotope composition, we conclude that: (1) the zinc isotopic compositions of sphalerite from the eastern and western ore belt of the Baiyangping polymetallic ore deposits are enriched in both the heavy (− 0.09‰ to + 0.15‰) and light (− 0.19‰ to − 0.01‰) zinc isotopes. Rayleigh fractionation is likely the additional factor controlling the observed temporal and spatial variations in zinc isotopes in the two studied ore zones. The zinc isotopic composition in the Baiyangping polymetallic Pb–Zn deposits may have the same fractionation as that of magmatic-hydrothermal, VHMS, SEDEX, and MVT deposits, as demonstrated by geological and other geochemical evidence; (2) the range of δ65Cu in massive tetrahedrite is from − 0.06‰ to + 0.12 ‰ that relates to the early stages of ore-formation, which are higher than that of venial chalcopyrite (from − 0.72‰ to − 0.07‰) formed at a late ore-forming stage in the western ore belt. Different ore-forming stages and alteration or leaching processes are likely the main factors controlling the observed variations in copper isotopes in the western ore zone; (3) the 87Sr/86Sr value of hydrothermal calcite in eastern (0.7080–0.7093) and western (0.7085–0.7113) ore belt suggested that mineralization of early calcite, with 87Sr/86Sr values much higher than in ancient Late Triassic seawater, may be related to recrystallization from a radiogenic Sr-rich or silicifying fluid, either from the strata that the ore-forming fluid flows through or from other fluids.

Most of the World’s large tungsten deposits are genetically related to fluorine-rich granitic magmas, their ores contain fluorine minerals, such as fluorite and topaz, and their host rocks have commonly undergone fluorine metasomatism to form greisens. In view of this evidence that tungsten ore fluids are enriched in fluorine, and the potential for fluoride to form stable complexes with hard acids (e.g., W6+), we investigated the solubility and speciation of tungsten in fluoride-bearing fluids at hydrothermal conditions. Experiments were conducted to measure the solubility of tungsten trioxide solid in fluoride-bearing aqueous fluids at temperatures between 100 and 250 °C and vapour-saturated water pressure. Based on the results of these experiments, tungsten is dissolved predominantly as H3WO4F2− in solutions containing 0.05–0.30 m HF at pH(T) values between 1.5 and 3.4. Significantly, the concentration of H3WO4F2− was up to two orders of magnitude higher than that of tungstate species in these experimental solutions. This species formed via the reaction WO3cryst + H2O + 2HF = H3WO4F2− + H+, logarithms of the equilibrium constants for which, vary from −4.39 ± 0.18 at 100 °C to −5.10 ± 0.17 at 250 °C. In solutions containing

A genetic link between Sb mineralization and magmatism has previously been proposed, yet little is known about the mobility of Sb during magma degassing. We have carried out a series of experiments to understand the effects of fluid composition, oxygen fugacity (fO2), pressure and temperature on the partitioning of Sb between magmatic fluids and a rhyolitic melt at crustal conditions (T = 850 °C, P = 200 MPa). The experiments were carried out in Molybdenum - Hafnium Carbide (MHC) pressure vessel assemblies at T = 850 to 1000 °C, P = 100 to 200 MPa and logfO2 from 1.64 log units below to 1.78 log units above the Ni-NiO buffer. Antimony partitions into aqueous chloride-bearing fluids weakly, with the fluid/silicate melt partition coefficient of Sb (DSbfluid/melt) increasing from 0.48 ± 0.11 (1σ) to only 0.85 ± 0.17 (1σ) as the total chlorine concentration in the fluid increases from 0.99 to 16.24 m, indicating the lack of significant Sb-chloride species in the fluid. In contrast, DSbfluid/melt increased from 0.89 ± 0.19 to 1.49 ± 0.19 as the aluminum saturation index (ASI) of the melt increased from 1.02 to 1.24. The moderate increase in DSbfluid/melt with increasing ASI of the melt (and HCl/metal chloride in the fluid) most likely relates to decreasing Sb solubility in the melt and further demonstrates the lack of significant chloride complexing of Sb. We also found that DSbfluid/melt is only slightly influenced by fO2 suggesting that Sb does not change oxidation state (Sb3+) at redox conditions typical of arc magmatism. Furthermore, the presence of reduced S species in the fluid phase caused only a minor increase in DSbfluid/melt indicating that Sb-sulfide complexes are not particularly stable in magmatic fluids. Our data also show that pressure and temperature, within the range of 100 to 200 MPa and 850 to 1000 °C, do not significantly influence DSbfluid/melt. Thus it is apparent that at most possible conditions at which rhyolitic melts degas in the upper crust, Sb will only weakly partition into the fluid phase and it is likely that the Sb budget of large epithermal Sb deposits is not directly derived from primary magmatic fluids.

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.

Permian-Triassic granites and associated tin deposits are widespread in the Eastern and Western belts of Peninsular Malaysia. The ages and key controlling factors of tin mineralization, however, are poorly constrained. Cassiterite separates from the Sintok and Rahman tin deposits in the Western belt, and Bandi, Setahum, Lembing, and Cherul tin deposits in the Eastern belt have U-Pb ages of 218.9 ± 3.4 and 226.8 ± 7.6 Ma, and 213.1 ± 3.9, 270.6 ± 4.6, 282.7 ± 4.6, and 281.3 ± 3.5 Ma, respectively. These ages directly constrain the tin mineralization in Peninsular Malaysia to two separate periods: 290 to 270 Ma and 230 to 210 Ma. Zircon crystals from tin-bearing granites in the Cherul and Sintok deposits have U-Pb ages of 276.0 ± 1.9 and 221.9 ± 0.6 Ma, respectively, consistent with the cassiterite U-Pb ages within uncertainties. Zircon crystals from barren granites of the Kuantan pluton in the Eastern belt have a U-Pb age of 260.5 ± 0.7 Ma, which is between the two tin mineralization periods. Zircon from these barren granites have εHf(t) values from −5.4 to 3.6, two-stage Hf model ages (TDM2) from 1.4 to 1.0 Ga, and Ce4+/Ce3+ ratios from 40 to 120. By comparison, zircon crystals from the tin-bearing granites have low εHf(t) values (−9.7 to −3.2) and Ce4+/Ce3+ ratios (4–67) and high TDM2 (1.8–1.4 Ga). Zircon ages, Hf isotopes, and trace elements indicate that the tin-bearing granitic magmas in Peninsular Malaysia had relatively low oxygen fugacity and were derived from reworking of Paleo- to Mesoproterozoic sedimentary rock-dominated crust in response to the Paleo-Tethyan subduction and continental collision. This study confirms that the nature of magma sources and redox states of magmas were key in the formation of the tin-rich granites and associated tin deposits and that the granite-related tin mineralization in Peninsular Malaysia was closely related to the evolution of the eastern Paleo-Tethys.

It has been well established that metal and sulfur sources in mineral deposits can be very difficult to identify, especially for ore deposits hosted in sedimentary rocks. Using the world’s largest Sb deposit at Xikuangshan in southern China as a case study, this study combined Hg isotopes and in situ sulfur isotope measurements to constrain the sources of Sb and sulfur. A variation of 1.1‰ in δ202Hg (0.04 to 1.15‰) was observed in stibnite ore samples, suggesting that mass-dependent fractionation of Hg isotopes occurred during the formation of the deposit. Significant mass-independent fractionation of Hg isotopes, with △199Hg ranging from − 0.03 to − 0.17‰, was also observed in the ore samples, suggesting that Hg transported by the ore fluids was inherited from Proterozoic basement metamorphic rocks as these rocks show similar △199Hg signatures (− 0.03 to 0.07‰). In situ sulfur isotope measurements yielded δ34S values that cluster in the range of + 6.8 to + 10.2‰, providing evidence that sulfur contained in ore fluids may also have been dominantly derived from underlying Proterozoic basement metamorphic rocks (δ34S = +5.6 to + 11.5‰). Using the new results from Hg and S isotopes, we proposed that deep-circulated meteoric water mobilized Sb, Hg, and S from the Proterozoic metamorphic basement, ascended along deep faults, and subsequently deposited Sb at favorable structural zones as a result of boiling of the hydrothermal fluids, generating the world-class Xikuangshan Sb deposit. This study also highlights the combined use of Hg-S isotopes as a novel method to provide new and additional insights into the source regions of ore materials for sedimentary-hosted Sb deposits.

The Shuiyindong Carlin-like gold deposit, the largest one of this type in China, is located in the Late Paleozoic–Early Mesozoic Youjiang basin. The pyrites in the studied ore bodies (No. I to V) can be divided into four main types plus several sub-types: (1) As-poor pyrites include Py1 (Py1a and Py1b), Py2, and Py3; and (2) As-rich pyrite Py4 (Py4a and Py4b). In situ LA-ICP-MS analyses show that the As-rich pyrite also contains higher Au, Cu, Sb, and Tl than the other pyrite types. In situ NanoSIMS analyses show the δ34S variation of Py1 (48.1~67.5‰), Py2 (2.4~7.6‰), Py3 (9.2~14.2‰), and Py4 (− 3.0~6.6‰), with the average values of 58.1‰, 5.1‰, 11.4‰, and 3.1‰, respectively. The large δ34S variations of As-poor pyrites may reflect a sedimentary source. However, the narrow ranges of δ34S values for the As-rich pyrite (Py4) may not reflect a sedimentary but a magmatic or metamorphic origin. A metamorphic sulfur source of Py4 is favored due to paucity of coeval magmatism in the region and decreasing variations of δ34S values from Py1 to Py4. Integrated transmission electron microscope (TEM) and NanoSIMS element mapping show that the distribution and concentration of Au are discordant with As and Cu at the submicron scale, also implied by the occurrence of some of Au as nano-submicron particles in Py4. Overall, our new data indicate that the ore fluids were not only enriched in Au but also in As, Cu, and S. Taking an alternative of fluid oxidation probably resulting in the decreasing δ34S values of Py4, our result of I to V orebodies indicates the mixing between the underlying metamorphic fluid and meteoric water. Integrated variations in δ34S and As-Au-Cu correlations across individual pyrite grains infer the physicochemical changes of aqueous and/or aqueous-carbonic fluids along migration paths.

The Xikuangshan Sb deposit in central Hunan, South China is the largest Sb deposit in the world, which has supplied more than 50% of the world’s Sb and with total Sb metal reserves of about 2.5 Mt. However, the age of this deposit is still not well constrained due to a lack of suitable minerals for reliable radiometric dating, which hampered the generation of a generally accepted genetic model of mineralization. Since the fluid-inclusion data suggest that the temperature of ore-forming fluids in the Xikuangshan deposit is up to 360 °C, zircon (U-Th)/He thermochronometry with the closure temperature of 160–200 °C was chosen here to elucidate the age of Sb mineralization. Detrital zircons in the altered host rocks from the Xikuangshan deposit yielded two (U-Th)/He age populations of 156–117 and 97–86 Ma. The older age population (156–117 Ma), which is well in accordance with previous Sm-Nd dating on hydrothermal calcite (156–124 Ma), probably represents the timing of main-stage Sb mineralization in the Xikuangshan Sb deposit, while the younger zircon (U-Th)/He ages may result from partial loss of He in zircon caused by the distal effect of deep-seated intrusions beneath the deposit. This study demonstrates that the (U-Th)/He dating of zircon in altered host rocks can be viable for constraining the timing of low-temperature mineralization.

Carlin-style (sediment-hosted, “invisible” gold) and epithermal gold deposits are commonly enriched in mercury (Hg), but the source of this metal is not well-known. In the world, the association of...

The Sichuan–Yunnan–Guizhou metallogenic province of Southwest China contains more than 200 Mt of Pb–Zn ore in carbonate-hosted Pb–Zn deposits, representing ~ 27% of the total Pb and Zn resources of China. Sources of metals and pathways of ore-forming fluids were elucidated through a study of the Pb–Zn–S–Cd isotopic compositions of sphalerite from the Tianbaoshan, Fusheng, Maozu, Jinshachang, and Daliangzi carbonate-hosted Pb–Zn deposits. δ34S values indicate that S in the deposits is derived mainly from evaporites in Cambrian to Triassic sedimentary strata, sulfates coexisting with sulfides, and Meso–Neoproterozoic folded basement. δ66Zn values and Pb isotopic ratios indicate that these metals originate mainly from Sinian to lower Permian sedimentary rocks and Proterozoic basement. There is a trend towards isotopically heavier Cd and Zn compositions of sphalerite from Maozu to Daliangzi, Jinshachang, and Tianbaoshan, which are all hosted in the upper Sinian Dengying Formation. Previous studies showed that there would be a trend of enrichment in heavier Zn and Cd isotopes following the migration of fluids and precipitation of minerals. The above observations suggest that the ore-forming fluids of these deposits are probably derived from the same hydrothermal fluid system. The fluids most likely flowed through Maozu first, migrating along the Xiaojiang and Anninghe fault belts and their branch faults to Daliangzi, Jinshachang, and Tianbaoshan, respectively. Zn and Cd isotopes could be useful tools in tracing the pathways of ore-forming fluids in this district, and heavier Zn and Cd isotopic compositions could provide a geochemical fingerprint for detecting remote orebodies in large hydrothermal fluid systems.

Chemical weathering of silicate rocks controls the fluvial input of dissolved Ge and Si into the ocean, and has substantial influence on the global Ge and Si geochemical cycles. The heavier dissolved Ge isotope compositions in the rivers (relative to the bulk silicate earth) suggest preferential incorporation of light isotopes into secondary weathering products during rock weathering (Baronas et al., 2017a). In this paper, we present the Ge isotope and Ge/Si ratio variations in the solid weathering products (soil and saprolite) from a well-developed basalt weathering profile (>15 m thick, including soil, saprolite, semi-weathered rock and fresh basalt) on the tropical island of Hainan (South China). We discussed the elemental/isotopic fractionation mechanism and the possible influence of major oxide composition on Ge isotope fractionation during extreme weathering of basalts in tropical climate. The Ge content ([Ge] = 2.19–4.12 ppm, 2.93 ppm on average, n = 52) and Ge/Si ratios (5.55–13.7 μmol/mol, 7.42 μmol/mol on average, n = 52) of solid weathering products are distinctly higher than those of the fresh basalts (avg. [Ge] = 1.64 ppm, Ge/Si = 2.66 μmol/mol, n = 5). The δ74Ge values of solid weathering products range from −0.02 ± 0.10‰ (2σ) to 0.63 ± 0.10‰ (2σ), and exhibits complex stratigraphic variation across the weathering profile. There are no distinct correlations between the concentrations of Ge (or the Ge/Si ratio and δ74Ge values) and SiO2, Al2O3, Fe2O3 and MnO for most of the soil and saprolite samples. The distinct positive δ74Ge vs. Ge (or τGe value and Ge/Si ratio) correlations for most soil and saprolite samples indicate that the enrichment (or depletion) of Ge content, Ge isotopes and Ge/Si fractionation are controlled by a common sorption process of solid weathering products. The predicted opposite relationships between Ge/Si ratios and δ74Ge values for pore water and that for solid weathering products can be evidenced by the positive Ge/Si vs. δ74Ge correlation in the Wenchang basalt weathering profile and a negative one in the river water (Baronas et al., 2017a). Moreover, the estimated negative Δ74Gesolid-dissolved (1000 * Ln(α)) value (−1.38 ± 0.28‰ (2σ)) indicates that solid weathering products are a sink for light Ge isotopes, possibly balancing the isotopic budget with heavy Ge isotope compositions in global rivers and oceans.

The Huize Zn–Pb–Ag deposit in SW China has an ore reserve in excess of 5 Mt. with an ore grade of ≥25 wt% Zn + Pb and 46–100 g/t Ag. This deposit is hosted in Carboniferous dolostone and limestone. Sulfide mineralization is dominated by sphalerite, galena, and pyrite. Four types of pyrite (Py1 to Py4) are temporally and spatially related to mineralization distinguished on the basis of textural features and mineral associations. Pyrite 1 to 3 corresponds to the pyrite-sphalerite sub-stage, whereas Py4 corresponds to sphalerite-galena-pyrite sub-stage. Pyrite 1 shows zoned texture composed of an inclusion-rich core and an inclusion-free rim, whereas Py2, Py3, and Py4 show replacement relic or overgrowth textures. The zoned texture in Py1 was formed by multiple stages of ore fluids, whereas replacement relic texture in Py2 to Py4 was formed by replacement of pyrite by late Pb-Zn-rich fluids. Trace element variation in pyrite results from a combination of mineral inclusions, co-precipitating minerals, and various fluid compositions. Sphalerite, pyrite, and galena have δ34S values of 10.4–23.5‰, suggesting that sulfur was probably derived from the thermochemical reduction of marine sulfates. The Huize pyrite has Co and Ni concentrations (0.02–9.5 ppm and 0.08–143 ppm, respectively) and Co/Ni ratios (~0.01–2.63) similar to pyrite from sedimentary exhalative deposits, submarine hydrothermal vents, and sedimentary pyrite, which may be due to pyrite precipitation from low-temperature (

Chemical weathering of rocks has substantial influence on the global geochemical cycle. In this paper, the geochemical profile of a well-developed basalt weathering profile (>15 m thick, including soil, saprolite, semi-weathered rock and fresh basalt) on the Island of Hainan (South China) was presented. The soil and saprolite samples from this profile are characterized by high Al2O3 and Fe2O3 concentrations (up to 32.3% and 28.5%, respectively). The mineral assemblage is dominated by kaolinite, Fe-oxides/-hydroxides and gibbsite (or boehmite), indicating extensive desilicate and ferrallitic weathering. The acidic and organic-rich environment in the soil horizon may have promoted elemental remobilization and leaching. The strongest SiO2 depletion and Al2O3 enrichment at about 2.4 m deep indicate that the main kaolinite hydrolysis and gibbsite formation occurred near the soil-saprolite interface. The mild Sr reconcentration at about 3.9 m and 7.1 m deep may be attributed to secondary carbonate precipitation. Mn-oxides/-hydroxides precipitated at 6.1 m deep, accompanied by the strongest enrichment of Ba and Co. Uranium is mildly enriched in the middle part (about 7.1 m and 9.1 m deep) of the weathering profile, and the enrichment may have been caused by the decomposition of uranyl carbonates or the accumulation of zircon. Immobile element (i.e., Zr, Hf, Nb, Ta, Th and Ti) distributions at different depths are mainly controlled by secondary Fe-oxides/-hydroxides, and follow the stability sequence of Nb ≈ Ta ≈ Th > Zr ≈ Hf > Ti. The limited thickness (∼15 cm) of the semi-weathered basalt horizon at the rock-regolith interface (15.28 m deep) suggests that plagioclase and pyroxene are readily altered to kaolinite, smectite and Fe-oxides under tropical climate. The marked enrichment of transitional metals (such as Cu, Zn, Ni, and Sc) along the rock-regolith interface may have associated mainly with increasing pH values, as well as the dissolution of primary apatite and formation of secondary phosphates. Our findings highlight the importance of secondary phosphates in the redistribution of transition metals, and in the possible Mg, Cu, and Ni isotopic fractionation under extreme weathering of basalt in tropic climate.

Sulfur isotope signatures of Au-bearing pyrite from Lannigou Au deposit, a typical Carlin-type Au deposit in SW China, provide valuable information about the origin of the ore-forming minerals. Analysis by NanoSIMS was used to determine S isotope compositions of Au-bearing pyrite and to map the grain-scale distributions of Au, Cu, As and S in pyrite from the deposit. Based on different textural pattern of pyrites revealed by back-scattered electron (BSE) images, they are divided into three types: Py-1 diagenetic pyrite without core-rim structure, Py-2 pyrite with an Au-free core and a rhythmically-zoned Au-bearing rim, Py-3 Au-bearing pyrite with rhythmic zoning across the entire grain. The element distributions and S isotope compositions of four paragenetic stages are recognized on the basis of textural observation. Py-1 grains and the Au-free homogeneous cores of zoned crystals were formed in Stage 1 while the Au-bearing rims of the zoned crystals with rhythmic zonation of As and Cu, and to a lesser degree Au, were formed in two superimposed stages: stage 2 formed the inner zone that is enriched in As alone; and stage 3 formed the outer zone that is enriched in both Au and As. Other sulfides such as realgar, cinnabar and stibnite are formed in the last stage. The relationship between Au and As distributions in pyrite rim is complicated, changing from coupled to decoupled at the nanoscale. Such complexity is interpreted to reflect fluctuation of fluid composition and temperature with time, which in turn affect the modes of occurrence of As and Au. It is inferred that As mainly occurs in the crystal lattice replacing S whereas Au is mainly present as nanoparticles that were trapped in pyrite during crystal growth. The Au-bearing rims of the zoned pyrite crystals are characterized by highly variable δ34S values from 1.1 to 18.1‰, which exceed the values of the Triassic calcareous host rocks (10–14‰). In contrast, the δ34S values of the Au-free cores of zoned pyrite crystals vary over a narrower interval and are mainly between 6 and 12‰, close to the values of pyrite crystals in the sedimentary country rocks. Our new analyses also reveals that the δ34S values of the Au-bearing fluids generally increase during the formation of the deposit. The observed S isotope variations are consistent with mixing between a magmatic-related fluid with mantle-like δ34S value (∼0‰) and a sedimentary or deep basin brine fluid with elevated δ34S value (>18‰), with an increasing contribution from the latter with time. The notably varied values of δ34S and the disseminations of Au and other trace elements such as As and Cu in pyrite crystals indicate that the process responsible for Au precipitation in this deposit occurred in an open hydrothermal system.

The Huayangchuan deposit in the North Qinling alkaline province of Central China is a unique carbonatite-hosted giant U–Nb–REE polymetallic deposit. The mineralization is characterized by the presence of betafite, monazite, and allanite as the main ore minerals, but also exhibit relatively high budgets of heavy rare earth elements (HREE = Gd–Lu and Y). The origin of carbonatites has long been controversial, thus hindering our understanding of the genesis of the deposit. Here, we conducted an in-situ trace elemental, Sr–Nd isotopic, and bulk C–O isotopic analyses of multi-type calcites in the deposit. Two principal types (Cal-I and Cal-II), including three sub-types (Cal-I-1, Cal-I-2 and Cal-I-3) of calcites were identified based on crosscutting relationships and calcite textures. Texturally, Cal-I calcites in carbonatites display cumulates with the grain size decreasing from early coarse- (Cal-I-1) to medium- (Cal-I-2) and late fine-grained (Cal-I-3), whereas Cal-II calcites coexist with zeolite displaying zeolite–calcite veinlets. Geochemically, Cal-I calcites contain relatively high REE(Y) (151–2296 ppm), Sr (4947–9566 ppm) and Na (29–390 ppm) contents, characterized by right- to left-inclined flat distribution patterns [(La/Yb) N = 0.2–4.2] with enrichment of HREE(Y) (136–774 ppm), whereas Cal-II calcites display low REE , Sr and undetectable Na contents, characterized by a right-inclined distribution pattern [(La/Yb) N = 13.5, n = 16]. The U–Nb–REE mineralization, accompanied with intense and extensive fenitization and biotitization, is mainly associated with the Cal-I-3 calcites which show flat to relatively left-inclined flat REE distribution patterns [(La/Yb)N = 0.2–1.0]. Isotopic results show that Cal-I calcites with mantle signatures are primarily igneous in origin, whereas Cal-II are hydrothermal, postdating the U–Nb–REE mineralization. Cal-I calcites (Cal-I-1, Cal-I-2 and Cal-I-3) from mineralized and unmineralized carbonatites, displayed regular changes in REE, Na and Sr contents, but similar trace element distribution patterns and Sr–Nd-C-O isotopic signatures, indicating that these carbonatites originated from the same enriched mantle (EM1) source by low-degree partial melting of HREE-rich carbonated eclogites related to recycled marine sediments. The combination of trace elements and Sr-Nd isotopic composition of calcites further reveals that these carbonatites have undergone highly differentiated evolution. Such differentiation is conducive to the enrichment of ore-forming elements (U–Nb–REE) in the late magmatic–hydrothermal stages owing to extensive ore-forming fluids exsolved from carbonatitic melts. The massive precipitation of the U–Nb–REE minerals from ore-forming hydrothermal fluids may have been triggered by intense fluid–rock reactions indicated by extensive and intense fenitization and biotitization. Therefore, the Huayangchuan carbonatite-related U-Nb-REE deposit may have formed by a combination of processes involving recycled U–Nb–REE–rich marine sediments in the source, differentiation of the produced carbonatitic magmas, and subsequent exsolution of U–Nb–REE–rich fluids that precipitated ore minerals through reactions with wall rocks under the transitional tectonic regime from compression to extension at the end of Late Triassic.

The advent of multiple collector–inductively coupled plasma–mass spectrometry (MC-ICP-MS) has made the high-precision determination of Ge isotopes possible, which leads to the widespread ap...

Mercury (Hg) isotopes have been proven as a useful tracer in understanding sources and biogeochemical processes of Hg in the environment. However, the use of this tracer has not yet been explored in economic geology. This paper investigates the concentrations and isotopic compositions of Hg in sulfide minerals from the Jinding deposit, the largest Zn-Pb deposit in China. Total mercury concentration (HgT) is highly variable: with the highest in sphalerite (472–1010 ng·g−1), intermediate concentrations in pyrite (195–342 ng·g−1) and the lowest in galena (65–310 ng·g−1). The variation was likely due to the fact that Hg2+ can more readily substitute for Zn2+ than for Fe2+ and Pb2+, but an influence of different parental fluids on the isotopic composition of the sulfide minerals cannot be excluded. An overall range of δ202Hg from −3.17 to −0.57‰ is observed in the sulfides. Samples from the early stage feature the enrichments of light Hg isotopes, with δ202Hg ranging from −3.17 to –1.59‰, suggesting significant mass-dependent fractionation during the transport and/or deposition of Hg. However, the volatilization of aqueous Hg(0) during boiling of hydrothermal fluids was likely the most important process causing the observed fractionation. Relatively higher δ202Hg values (−1.84 to −0.57‰) of the late stage samples indicate that the Hg was rarely fractionated from its sources. Additionally, small but significant mass-independent fractionations are measured for the deposit with Δ199Hg ranging from −0.06 to 0.10‰, indicating that the Hg may have been derived from the sedimentary rocks of the Lanping Basin. Finally, we conclude that Hg isotopes have the potential to be a new tracer of sources of ore-forming materials, as well as pathways of fluid evolution in hydrothermal deposits.

Lanping basin is a large Pb-Zn-Cu-Ag polymetallic mineral province in SW China, with major deposit types including vein-type Cu deposits, basinal brine-related Pb-Zn deposits (e.g., Liziping, Fulongchang) and minor quartz-vein-type Pb-Zn deposits (e.g., Shangnuluo, Baiji). In this study, we have conducted EPMA and LA-ICP-MS sphalerite trace element analyses, together with gangue carbonate C-O stable isotope analysis and molybdenite Re-Os dating. Using these data, we discuss the mineral assemblage, sphalerite minor/trace element composition, ore-fluid source, and mineralization age of these two types of Pb-Zn deposits. Except sphalerite and galena, major ore minerals from Liziping and Fulongchang are As-rich (e.g., gratonite, jordanite, bournonite, As-rich pyrite), whereas those from Shangnuluo and Baiji are Sb-rich (e.g., boulangerite, jamesonite, stibnite, zinkenite). The trace element compositional characteristics in sphalerite of these deposits (low Mn, Fe, Co, In and Sn, and high Cd) mimic those of medium-low-temperature hydrothermal deposits (MVT and Jinding deposits). For the Liziping zoned sphalerite, the dark-brown zones have relatively high Co, Cu, Ga, As, and Sb; whilst the light-colored zones have relatively high Fe, Mn and Cd. The calculated sphalerite formation temperature based on sphalerite geothermometer – GGIMFis ( Frenzel et al., 2016 ) are basically in agreement with those homogenization temperature of inclusions, indicating that the contents of these elements (Ga, Ge, Fe, Mn and In) in sphalerite are mainly controlled by temperature. Moreover, the estimated sulfur fugacity (log fS2) for Liziping (−14.7) and Fulongchang (−13.6) are distinctly lower than those for Shangnuluo (−7.1) and Baiji (−8.5). Carbonate C–O isotope compositions indicate that the dissolved carbon and oxygen of ore forming-fluids of these Pb-Zn deposits were mainly derived from sedimentary carbonate dissolution. Early-ore-stage molybdenite from Baiji deposit yielded two Re-Os weighted average model ages of 21.4 Ma and 12.93 Ma, and a Re-Os concordia age of 11.88 ± 0.77 Ma was obtained from four younger molybdenite samples. These ages are distinctly younger than those reported mineralization age (ca. 30 Ma) for basinal brine-related Pb-Zn deposits. All these results indicate that there are two different types of Pb-Zn metallogenic events in the northern margin of Lanping Basin.

Organic-rich shales exhibit a wide range of vanadium (V) concentrations in deep-time successions. Although V accumulation is generally acknowledged to be related to redox state, organic matter and clay mineral content, previous studies have failed to explain the mechanism of variable V enrichment in organic-rich shales. Here, we hypothesize that clay-organic nanocomposites control authigenic V uptake in organic-rich shales. Specifically, V is scavenged by dissolved organic matter in seawater, which is then taken up by smectite during transport or deposition, followed by V incorporation into illite through illitization of smectite and pyrolysis of organic matter during diagenesis. To test this hypothesis, lower Cambrian black shales from South China were investigated by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) at a micro- and nanoscale. Results show that only 1M/1Md-type illite, generated through transformation from a smectite precursor, has significant V concentrations (0.7–4.8 wt%), whereas 2M1-type illite and other minerals contain little or no V. All 1M/1Md-type illite was closely associated with organic matter, occurring as clay-organic nanocomposites. Our results are significant in (i) showing clay-organic nanocomposites play a key role in V cycling in the marine system, (ii) providing a mechanism for understanding variations in the V concentrations of deep-time organic-rich shales, and (iii) improving strategies for prospecting and extraction of V ores.

Extremely elevated Hg levels up to the μg g − 1 range were found in sulfide-rich black shale and phosphorite in the lowermost part of the Early Cambrian black shale sequences on the Yangtze Platform in South China. In this study, mercury isotopes were used to help resolve the origin of this anomalous Hg enrichment. Mass independent fractionation signatures of Hg isotopes with positive Δ 199 Hg values of 0.13 to 0.24‰ and positive Δ 200 Hg values of 0.05 to 0.10‰ were observed, indicating seawater is an important source of Hg. We hypothesize that upwelling of nutrient-rich waters from the open ocean resulted in high bioproductivity in the photic zone with concomitant scavenging of Hg from seawater. Advanced decay of biomass and remineralization under anoxic to euxinic conditions combined with very low clastic input led to enrichment of Hg and a broad spectrum of other redox-sensitive and biogenic metals up to 10 7 compared to modern seawater. Such spectacular hydrogenous metal enrichment has previously been observed in the oxic deep-sea environment only, i.e. manganese crusts/nodules.

The Jinman Cu polymetallic deposit is located within Middle Jurassic sandstone and slate units in the Lanping Basin of southwestern China. The Cu mineralization occurs mainly as sulfide-bearing quartz–carbonate veins in faults and fractures, controlled by a Cenozoic thrust–nappe system. A detailed study of fluid inclusions from the Jinman deposit distinguishes three types of fluid inclusions in syn-ore quartz and post-ore calcite: aqueous water (type A), CO2–H2O (type B), and CO2-dominated (type C) fluid inclusions. The homogenization temperatures of CO2–H2O inclusions vary from 208°C to 329°C, with corresponding salinities from 0.6 to 4.6 wt.% NaCl equivalent. The homogenization temperatures of the aqueous fluid inclusions mainly range from 164°C to 249°C, with salinities from 7.2 to 20.2 wt.% NaCl equivalent. These characteristics of fluid inclusions are significantly different from those of basinal mineralization systems, but similar to those of orogenic or magmatic mineralization systems. The H and O isotope compositions suggest that the ore-forming fluid is predominantly derived from magmatic water, with the participation of basinal brine. The δ34S values are widely variable between −9.7 ‰ and 9.7 ‰, with a mode distribution around zero, which may be interpreted by the variation in physico-chemical conditions or by compositional variation of the sources. The mixing of a deeply sourced CO2-rich fluid with basinal brine was the key mechanism responsible for the mineralization of the Jinman deposit.

The Lanuoma and Cuona sediment-hosted Pb-Zn deposits hosted by Upper Triassic limestone and sandstone, respectively, are located in the Changdu area, SW China. Mercury concentrations and Hg isotopic compositions from sulfide minerals and potential source rocks (e.g., the host sedimentary rocks and the metamorphic basement) were investigated to constrain metal sources and mineralization processes. In both deposits, sulfide minerals have higher mercury (Hg) concentrations (0.35 to 1185 ppm) than the metamorphic basement rocks (0.05 to 0.15 ppm) and sedimentary rocks (0.02 to 0.08 ppm). Large variations of mass-dependent fractionation (3.3‰ in δ202Hg) and mass-independent fractionation (0.3‰ in Δ199Hg) of Hg isotopes were observed. Sulfide minerals have Hg isotope signatures that are similar to the hydrothermal altered rocks around the deposit, and similar to the metamorphic basement, but different from barren sedimentary rocks. The variation of ∆199Hg suggests that Hg in sulfides was mainly derived from the underlying metamorphic basement. Mercury isotopes could be a geochemical tracer in understanding metal sources in hydrothermal ore deposits.

Magnetite is a very common mineral in various types of iron deposits and some sulfide deposits. Recent studies have focused on the use of trace elements in magnetite to discriminate ore types or trace ore-forming process. Germanium is a disperse element in the crust, but sometimes is not rare in magnetite. Germanium in magnetite can be determined by laser ablation ICP-MS due to its low detection limit (0.0X ppm). In this study, we summary the Ge data of magnetite from magmatic deposits, iron formations, skarn deposits, iron oxide copper-gold deposits, and igneous derived hydrothermal deposits. Magnetite from iron formations contains relatively high Ge (up to approximate to 250 ppm), whereas those from all other deposits mostly contains Ge less than 10 ppm, indicating that iron formations can be discriminated from other Fe deposits by Ge contents. Germanium in magmatic/hydrothermal magnetite is controlled by a few factors. Primary magma/fluid composition may be the major control of Ge in magnetite. Higher oxygen fugacity may be beneficial to Ge partition into magnetite. Sulfur fugacity and temperature may have little effect on Ge in magnetite. The enrichment mechanism of Ge in magnetite from iron formations remains unknown due to the complex ore genesis. Germanium along with other elements (Mn, Ni, Ga) and element ratios (Ge/Ga and Ge/Si raios) can distinguish different types of deposits, indicating that Ge can be used as a discriminate factor like Ti and V. Because of the availability of in situ analytical technique like laser ablation ICP-MS, in situ Ge/Si ratio of magnetite can serve as a geochemical tracer and may provide new constraints on the genesis of banded iron formations.

The southeastern part of the Nanling metallogenic province, South China contains numerous economically important granite-hosted, hydrothermal vein-type uranium deposits. The Miao’ershan (MES) uranium ore field is one of the most important uranium sources in China, hosts the largest Chanziping carbonaceous-siliceous-pelitic rock-type uranium deposit and several representative granite-hosted uranium deposits. The geology and geochemistry of these deposits have been extensively studied. However, accurate and precise ages for the uranium mineralization are scarce because uranium minerals in these deposits are usually fine-grained, and may have formed in several stages, thus hindering the understanding of the uranium metallogenesis of this province. The Menggongjie (MGJ) uranium deposit is one of the largest granite-hosted uranium deposits in the MES ore field. Uranium mineralization in this deposit occurs at the central part of the MES granitic complex, accompanied with silicification, fluorination, K-metasomatism and hematitization. The ore minerals are dominated by uraninite, occurring in quartz or fluorite veinlets along fractures in altered granite. In-situ SIMS U-Pb dating on the uraninite yields the U–Pb isotopic age of 1.9 ± 0.7 Ma, which is comparable to the chemical U-Th-Pbtol uraninite age of 2.3 ± 0.1 Ma. Such ages agree well with the eruption ages of the extension-related Quaternary volcanics (2.1–1.2 Ma) in South China, suggesting that the uranium mineralization have formed at an extensional setting, possibly related to the Quaternary volcanic activities. Therefore, our robust, new dating results of the MGJ uranium deposit make it the youngest granite-hosted uranium deposit reported so far in South China and the mineralization event represents a newly identified mineralization epoch.

The Zijinshan high-sulfidation epithermal Cu–Au deposit is located in the Zijinshan ore field of South China, comprising porphyry–epithermal Cu–Au–Mo–Ag ore systems. The Cu ore body is more than 1000 m thick and is characterized by an assemblage of digenite–covellite–enargite–alunite. Digenite is the dominant Cu-bearing mineral, which makes this deposit unique, although the mechanisms of digenite formation remain controversial. To elucidate the genesis of digenite, this paper presents the Cu isotopic compositions of Cu-sulfides in the Zijinshan high-sulfidation Cu–Au deposit. The Cu isotopic values (65Cu relative to NIST 976) of all samples range from −2.97‰ to +0.34‰, and most values fall in a narrow range from −0.49‰ to +0.34‰, which is similar to the Cu isotopic signature of typical porphyry systems. Copper isotope ratios of each mineral decrease with increasing depth, a trend that is also typical of porphyry deposits. The variation tendency of δ65Cu values between sulfides is consistent with the sequence of mineral formation. These observations suggest that the Cu-sulfides in the Zijinshan Cu–Au deposit have a hypogene origin.

We have used a multi-aliquot method to obtain precise (U + Th)/He ages of hydrothermal hematite and to assess the extent to which He loss from fine-grained hematite caused by diffusion and recoil. Hematite (n = 6) from the Rio Marina mine, Elba (Italy) yields (U + Th)/He ages that range from 5.36 ± 0.33 to 5.64 ± 0.11 Ma, giving a weighted mean age of 5.53 ± 0.14 Ma and an isochron age of 5.25 ± 0.20 Ma. 40Ar/39Ar data from cogenetic adularia yield flat age spectra with analytically indistinguishable plateau ages (5.575 ± 0.008 and 5.583 ± 0.013 Ma). An additional adularia has a more complex spectrum and yields an interpreted age of 5.64 ± 0.03 Ma. The hematite (U + Th)/He ages overlap the 40Ar/39Ar ages, albeit they are less precise (2–6% vs. 0.2–0.5%). This indicates that the loss of in situ radiogenic 4He from complex fine-grained hematite, either by diffusion and recoil, is insignificant. The study shows that multi-aliquot method has the potential to reliably deliver precise and accurate ages for iron oxide mineralisation that has not suffered significant post-crystallisation thermal perturbation.

Magnetite occurs as an ore mineral in many types of deposits and its trace element characteristics can be used to fingerprint various types of mineral deposits and distinguish different ore forming processes. The Lengshuikeng Ag–Pb–Zn deposit (LSKD) is one of the largest silver deposits in China, but the ore forming processes involved in its formation are still unclear. In this study, magnetites from six representative samples of different mineralization types were examined. Their trace element contents were analyzed using in situ laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS), to better understand the genesis and evolution of the ore-forming fluids responsible for Ag–Pb–Zn mineralization. The studied magnetites were divided into two types based on their spatial occurrence, associated minerals and distinctive textures. Type A magnetites are large, display subhedral to euhedral forms and appear inclusion-free. They coexist with siderites and formed early, preceding the formation of surrounding sulphides. Type B magnetites are small, exhibit irregular and anhedral forms that feature as wall-rock alterations, and were formed during the main mineralization stage. They coexist with main-stage sulphides and Fe-Mn-bearing carbonate minerals, in which Mn content increases corresponding to the evolution of the mineralization process. Generally, magnetites from the LSKD contain low amounts of Ti and V, and widely variable Al and Mn contents, which resulted from multiple influxes of low-temperature hydrothermal fluid. Type A magnetites are inferred to have formed paragenetically early at relatively high temperatures without coeval precipitation of base-metals. Conversely, Type B magnetites are interpreted to have formed during the early (B1, stage 1) and main (B2, stage 2) stages of Ag–Pb–Zn mineralization under alteration and dissolution–reprecipitation processes (DRP) from the later ore-forming hydrothermal fluids. Trace element characteristics of magnetite suggest the late hydrothermal fluid was characterized by low temperatures, and was enriched of Cl and Mn. The wide range of contents of trace elements (e.g. Ga, Mo and Sn) in magnetite that underwent DRP can be explained by different wall-rock types and water/rock ratios. Characteristics of the late hydrothermal fluids, including those from detailed microscopic observations, indicate that the ingress of Ag, Pb and Zn occurred as metal–Cl complexes, and that dissolution of early Fe, Pb, and Zn sulphides supplied the S required for the final precipitation of silver.

As one of the top ten countries with important uranium resources, China hosts most of the fifteen types of uranium deposits identified by International Atomic Energy Agency (IAEA), among which the economically most important ones are sandstone-type, granite-type, volcanic-type, and carbonaceous-siliceous-pelitic rock- or carbonate-type. This Special Issue provides an up-to-date perspective of the geological characteristics, metallogenic environments, ore-forming mechanisms and exploration methods by the Chinese uranium geoscience community, of the more important types of uranium deposits in China. Among the fourteen papers, six are on sandstone-type, two on volcanic-related, two on granite-related, two on intrusive-type, one on carbonaceous-siliceous-pelitic rock-type or carbonate-type, and one on IOCG or polymetallic iron oxide breccia complex-type. These papers provide useful references for comparison between the Chinese uranium deposits and their counterparts in other parts of the world, and will contribute to further advancement of the global uranium geoscience and resource exploration.

The Lanping basin is an important Pb-Zn-Cu-Ag polymetallic province in southwestern (SW) China. Mineralization types in the basin include mainly MVT Pb-Zn deposits, vein-type Cu deposits, and minor quartz vein-type Pb-Zn deposits. In this study, we analyzed the total Hg (THg) content and Hg-S isotopic compositions of sulfides from two types of Pb-Zn deposits in the basin, and investigate the Hg isotope fractionation mechanism and its major controlling factors in the Pb-Zn ore-forming process. At the Shangnuluo quartz vein-type Pb-Zn-Sb deposit, sulfides (especially sphalerite) show a wide δ202Hg range (−0.40 to 2.71‰), suggesting that Hg0 evaporation from hydrothermal fluids occurred during the ore formation. Negative THg vs. δ202Hg correlation in the sphalerites suggests a mixing of Hg from the vapor phase (low δ202Hg, high THg) and the residual aqueous phase (high δ202Hg, low THg). The negative ∆199Hg (−0.42 to −0.08‰) suggests that the Hg was sourced from the metamorphic basement, whereas the negative δ34S values (−13.0 to −2.7‰) suggests that the sulfur was mainly sourced from sedimentary sequences, possibly related to the organic matter decomposition and thermochemical sulfate reduction (TSR). For the Liziping and Fulongchang MVT Pb-Zn deposits, sulfides have relatively narrow δ202Hg range (−1.46 to 0.25‰), suggesting limited Hg0 evaporation during the mineralization. Lower δ202Hg values were observed in the early-stage sulfides from these two deposits, probably due to the preferential precipitation of lighter Hg isotopes in these early-stage sulfides. Sulfides from both deposits have negative ∆199Hg values (−0.24 to 0.01‰), suggesting that the Hg was also derived from the metamorphic basement. Sulfide δ34S values from the two deposits are positive, which also suggests that the sulfur was sourced from sedimentary sequences, but mainly related to TSR under relatively low-temperatures. Sulfides from different Pb-Zn deposit types in the Sanjiang Tethyans Metallogenic Belt fall into distinct fields in the δ34S vs. δ202Hg (or ∆199Hg) diagrams, indicating that the integration of S and Hg isotopes is useful to discriminate different types of Pb-Zn deposits.

Tin deposits are often closely associated with granitic intrusions. In this study, we analyzed tin partition coefficients between different fluids and melts ( $${\text{D}}_{Sn}^{aq.fl./melt}$$ ) as well as various crystals and melts $${\text{D}}_{Sn}^{aq.fl./melt}$$ ( $${\text{D}}_{Sn}^{crystal/melt}$$ ) from the Furong tin deposit associated with the Qitianling A-type granite. Our experimental results indicate that tin partition behavior is affected by the chemical compositions of fluids, melts, and minerals. Tin is prone to partitioning into the residual magma in fractional crystallization or other differential magmatic processes if the magma originated from crustal sources with high alkali content, high volatile content, and low oxygen fugacity. Highly evolved residual peralkaline granitic magma enriched in tin can lead to tin mineralization in a later stage. Furthermore, the volatiles F and Cl in the magma play important roles in tin partitioning behavior. Low F contents in the melt phase and high Cl content in the aqueous fluid phase are favorable factors for tin partitioning in the aqueous fluid phase. High Cl content in the aqueous fluid catalyzes water–rock interaction and leads to the extraction of tin from tin-bearing minerals. All these findings support a hydrothermal origin for the tin deposits. In light of the geotectonic setting, petrochemical characteristics, and mineralizing physicochemical conditions of the Furong tin deposit, it is inferred that the ore-forming fluid of the Furong tin ore deposit could have derived from the Qitianling peralkaline intrusion.

Miaoershan (MES) uranium ore field is one of the most important uranium sources in China, hosts the largest Chanziping carbonaceous-siliceous-pelitic rock type uranium deposit in South China together with many other granite-hosted uranium deposits. The Shazijiang (SZJ) uranium deposit is one of the representative granite-hosted uranium deposits in the MES uranium ore field, situated in the Ziyuan, Guangxi Province, South China. Uranium mineralization in the SZJ deposit mainly occurs as uraninite with quartz and calcite veins that is spatially associated with mafic dykes in the region. The hydrothermal alteration includes silicification, carbonation and hematitization. New uraninite chemical U-Pb geochronology and petrographic evidences provide the timing constraints and new insights into the formation of the SZJ uranium deposit. The results show that the first stage of uranium mineralization formed at 97.5±4.0 Ma, whereas another stage of uranium mineralization occurred at 70.2±1.6 Ma. Two stages of uranium mineralization are fairly consistent with two episodic crustal extensions that occurred at ~100 and ~70 Ma throughout South China. This study indicates that there are two uranium mineralization events in SZJ uranium ore field controlled by mafic dyke, supporting that mafic dykes play an important topochemical role in uranium concentration and/or mobilization. Therefore, geochemical U-Pb age firstly reinforces that ore-forming age of the SZJ uranium deposit mainly yields at 97.5±4.0 and 70.2±1.6 Ma. Additionally, geochemical age method is particularly useful for interest samples which record information on multi-stage uranium mineralizations in South China.

Though stibnite is among the most predominant Sb-bearing mineral phases in most Sb deposits, little is known about the trace elements and their substitution mechanism in stibnite that are valuable to better decipher the genesis of Sb deposits. This study determined quantitatively the trace element compositions of stibnite from two representative Sb deposits (Xikuangshan and Woxi) in southern China using high-resolution LA-ICP-MS. Results show that stibnite at Xikuangshan contains measurable Hg and As (typically 10–100 ppm); however, As, Cu, and Pb are the most abundant trace elements at Woxi (generally 100–500 ppm). Furthermore, the relatively smooth LA-ICP-MS profiles indicate As, Cu, and Pb primarily occurs as solid solution in stibnite. Hence the substitution 2Sb3+↔Cu++Pb2++As3+ is likely responsible for the enrichment of Cu, Pb, and As in stibnite. Other trace elements, including Au, Ag, Bi, In, Mo, Sn, Co, Cr, V, Zn, Ni, Ga, Ge, Rb, Sr, Pd, Cd and U, are generally at concentrations of 0.01–1 ppm, with spiky LA-ICP-MS depth profiles, which are indicative of their presence as sparse micro-inclusions within stibnite. The apparent differences in trace element concentrations of stibnite suggest that the stibnite from two deposits may have been generated by different processes, or may reflect differences in fluid chemistry. The relative enrichment of As, Cu, and Pb indicate that the original Sb-bearing fluids for the Woxi deposit were likely enriched in these elements in the source region, but a geochemical segregation led to the formation of stibnite-dominated ores. In contrast, the monomineralic ores at Xikuangshan was likely originated from an initial absence of these elements in their source regions. The Hg/(Cu + Pb) ratio for the Xikuangshan Sb deposits is typically greater than 1 but the Woxi deposit tends to be much lower than 1. Therefore, the differences in trace element composition in stibnite can be useful to discriminate between Sb deposit types.

The Lengshuikeng Ag-(Pb-Zn) deposit (LSKD) is one of the largest independent porphyry silver deposits in China. Its silver mineralization is related to the Late Mesozoic granite porphyry, but the oxidizing hydrous conditions of the associated magma are still unclear. This study focuses on the associated granite porphyry (GP) and barren K-feldspar granite porphyry (KFGP) to constrain their oxidizing hydrous conditions. New zircon U-Pb dating shows the GP emplaced at 155.8 ± 1.9 Ma and 158.5 ± 2.3 Ma for GP, and the KFGP emplaced at 136.6 ± 1.9 Ma. Both granites are peraluminous with A/CNK ratios of 1.09–3.01 (mean = 1.48), similar to that of typical S-type granites. They are enriched in light rare earth elements (LREE), with large (La/Yb)N (7.0–19.1 for the GP and 1.8–34.3 for the KFGP) and negative Eu anomalies (0.29–0.67 for the GP and 0.02–0.05 for the KFGP). The GP has eNd(t) values ranging from − 10.0 to − 9.7 with TDM2 ages of 1688–1915 Ma, while the KFGP has higher eNd(t) values ranging from − 7.5 to − 7.6 with younger TDM2 ages of 1538–1548 Ma. The initial Pb isotopic ratios for (206Pb/204Pb)i, (207Pb/204Pb)i and (208Pb/204Pb)i are 17.647–17.952, 15.555–15.604 and 37.851–38.541, respectively. Our new chemical and isotopic data suggest that both granites were dominantly derived from dehydration melting of the Proterozoic meta-sedimentary rocks, with more dehydration fluids for the GP and relatively more mantle contribution to the KFGP. Both granites underwent fractional crystallization of plagioclase, K-feldspar and ilmenite/magnetite followed by minor assimilation of the upper crust. Comparative study on the relative water content, oxidation state and melting temperature of magma have shown relatively moderate oxidation state and water content in the associated magma probably played more important roles in porphyry silver mineralization than other factors in porphyry Cu deposit. This study helps deepen the understanding of silver mineralization.

Abundant Carlin-type gold deposits and vein-type antimony deposits were discovered in the Youjiang basin of SW China, constituting the Youjiang Metallogenic Province (YMP). Although they had been widely studied by geologists, the genesis of these deposits remains debatable, while both intrusion-linked and non-intrusion linked models have been proposed. In this paper, new data of in situ trace elements (LA-ICP MS) and oxygen isotope (SIMS) analysis of hydrothermal quartz from the Yata Carlin-type gold deposit and the Qinglong vein-type antimony deposit in the province were provided to better understand the origin of ore-forming fluids as well as the genetic mechanism of Au and Sb mineralization. Four quartz generations were identified from the Yata (YTi to YTiv) and the Qinglong (QLi to QLiv) deposits. In the Yata deposit, the fluid inclusions in quartz have varied homogenization temperatures from 140–260 ℃ and salinities of 2.4–7.4 wt％ NaCleq, while in the Qinglong deposit, the temperatures and salinities ranged from 140–200 ℃ and 0.2–7.2 wt％ NaCleq., respectively. Both of the temperatures and salinities tend to decrease from early to late generations in the two deposits. δ18O values of initial fluids in the Yata (YTi: 7.70–10.56‰) and the Qinglong (QLi: 4.66–8.75‰) deposits are similar and suggest that they were mainly from magmatic or metamorphic fluids. The covariability of oxygen isotope and Al concentrations indicate that interaction between fluids and wall rocks is a significant factor in determining the compositions of fluids in Au mineralization, and the meteoric water is a key proxy in Sb mineralization, respectively. From these observations, we proposed that the Carlin-type Au deposit and vein-type Sb deposit in YMP were sourced from an analogous ore fluid. Different lithologies of wall rocks and the dilution of meteoric water controlled the compositional evolution of fluids, which might be the main reason for the diversity of Au and Sb mineralization.

The Carlin-type gold deposits in the Youjiang Basin, SW China can be further classified into three sub-types; strata-bound, fault-controlled, and diabase-associated. The compositions and sources of the ore-forming fluids for each deposit type are evaluated using the texture of calcite by CL (Cathode luminescence), its chemistry by EMPA (Electron probe microanalysis) and LA-ICP-MS (Laser ablation inductively coupled plasma mass spectrometry), and its C-O isotopic compositions by SIMS (Secondary ion mass spectroscopy). The studied deposits are the stratabound Zimudang deposit, the fault-controlled Lannigou deposit, and the diabase-associated Badu deposit. Calcite in the Zimudang and Lannigou deposits formed at three different stages: pre-ore stage pore-filling and massive calcite (Cal 1), late-ore stage vein calcite (Cal 2) associated with realgar and pyrite, and post-ore stage vein calcite (Cal 3). Calcite in the Badu deposit formed in two stages: ore stage vein and replacement calcite (Cal 2) associated with pyrite and post-ore stage calcites (Cal 3). Calcite with brighter red CL color has higher Mn and lower Fe content than calcite with darker red CL color. Furthermore, the higher the total REE content, the brighter the CL color. The host rocks are characterized by light REE (Rare earth element) enrichments. In contrast, the ore stage calcite shows middle REE enrichments. The ore stage calcite has higher concentrations of Fe, Mn, Mg, Si and Sr, and lower concentrations of Cu, Sb and Zn than both the pre- and post-ore calcite. The ranges of carbon (PDB) and oxygen (SMOW) isotope compositions of calcite are from −11.29 to 6.89‰ and from 16.49 to 22.60‰ for the Zimudang deposit, from −13.31 to 2.80‰ and from 9.12 to 29.71 for the Lanningou deposit, and from −11.94 to 0.49‰ and from 10.51 to 18.97‰ for the Badu deposit. Generally, the ore stage calcite has a wider range of δ13C and δ18O values than the other stage calcite. The isotope data indicate that a deep crustal fluid was involved in the formation of all of these three deposits. Meteoric water containing abundant organic matter was also involved in the formation of the Badu deposit as well as the Zimudang deposit, whereas a basin brine was also involved in the formation of the Lanningou deposit.

Determining Ge isotopic compositions of sulfides is important to understand the ore-forming processes. Single step anion-exchange chromatography was previously used to recover Ge from silicates and lignites. We apply this procedure to recover Ge from sulfides before determining Ge isotopic compositions by hydride generation (HG)-MC-ICP-MS. Germanium is quantitatively recovered by the proposed sample preparation method. There are no obvious isotope biases for Ge-bearing solutions containing significant amounts of Cu, Sn, and W. However, δ 74 Ge values show obvious shifts if the solutions contain high Zn, Pb, and Sb, which is possibly attributed to suppression of germane formation that fractionates Ge isotopes. The long-term reproducibility for Ge standard solution is about ± 0.18‰ for δ 74 Ge. Spex and Merck standard solutions yield mean δ 74 Ge values of − 0.70 ± 0.19‰ and − 0.36 ± 0.08‰, respectively. The calculated δ 74 Ge value (− 5.13‰) of sphalerite standard based on doping experiments is indistinguishable from those of sphalerite without doping (− 5.05‰ and − 5.01‰). Sulfides from the Jinding, Shanshulin, and Tianqiao Pb–Zn deposits in SW China have δ 74 Ge values of − 4.94‰ to + 2.07‰. The paragenetic sequence of sulfides from the Shanshulin and Tianqiao Pb–Zn deposits is pyrite, sphalerite and galena from early to late. Sulfides from the same ore show a trend of δ 74 Ge pyrite 74 Ge sphalerite 74 Ge galena , which may be controlled by the kinetic or Rayleigh fractionation.

The southeastern part of the Nanling metallogenic province, China is host to numerous granite-hosted vein-type hydrothermal uranium deposits. The geology and geochemistry of these deposits have been extensively studied. However, accurate and precise ages for the uranium mineralization are scarce because the uranium minerals in these deposits are usually fine grained, and may have formed in several stages. Therefore, the ages previously obtained by the bulk dating techniques are possibly a mixed age. The Xianshi uranium deposit, located in the southeastern part of the Guidong granite complex, is a major uranium deposit in South China. The uranium mineralization from this deposit is mainly fine grained uraninite in quartz or calcite veins which are spatially associated with the Cretaceous mantle-derived mafic dykes. Micro-Raman spectroscopy and X-ray diffraction analyses indicate that the dominant uranium mineral occurs as a rare form of uraninite (U 3 O 7 ). Three distinct generations of uranium minerals have been identified based on petrographic and field relations. Stage 1 uraninite has the lowest UO 2 and highest PbO contents whereas Stage 3 uraninite has the highest UO 2 and lowest PbO contents. Uraninite from the Xianshi deposit was dated using an in-situ SIMS U–Pb dating technique. The results show three distinct age groups: 135 ± 4 Ma, 113 ± 2 Ma and 104 ± 2 Ma, which are in excellent agreement with the ages of three episodes of mantle-derived mafic dykes. Therefore, the Xianshi uranium deposit has experienced at least three hydrothermal events that are responsible for the deposition of uranium ores, which are genetically related to the emplacement of three sets of mafic dykes.

The Yangla skarn Cu deposit (150 Mt at 1.03% Cu) is located in the central segment of the Jinshajiang metallogenic belt within the Sanjiang (Three Rivers) region, southwest China. Skarn orebodies are mainly developed between different units of Devonian carbonate and quartz sandstone rocks with stratiform-like shapes, or within the contact zone between granitoids and marbles. Re-Os dating of molybdenite intergrowth with chalcopyrite yielded a well-constrained 187Re-187Os isochron age of 232.0 ± 1.5 Ma with a weighted average age of 231.8 ± 1.3 Ma, both coeval with the related intrusions (233.1 ± 1.4 and 231.0 ± 1.6 Ma at 2 σ by zircon U-Pb dating) from our previously published work. Field and textural relationships indicate three hydrothermal stages characterized by assemblages of prograde skarn (pre-ore stage), retrograde skarn and Cu-Fe-Mo-Bi sulfides (main ore stage), and Pb-Zn sulfides associated with calcite and quartz (late ore stage), as well as one supergene stage marked by secondary Cu mineralization (malachite and azurite). Skarns contain garnets with andraditic compositions (Ad96 Gr2~3Py0~1) and clinopyroxene (two series: Hd6Di94 and Hd86Di13Jo1) with low Mn/Fe ratios (

Fe-Cu deposits in the Kangdian Fe-Cu metallogenic province, SW China, are hosted in Paleoproterozoic meta-volcanic-sedimentary sequences and are spatially associated with coeval mafic intrusions. Several well-known examples are the giant Lala, Dahongshan, and Yinachang deposits. They have a common paragenetic sequence of an early Fe-oxide stage associated with sodic alteration and a late Cu-sulfide stage associated with potassic-carbonate alteration. Magnetite dominates the Fe-oxide stage of these deposits but is also present in the Cu-sulfide stage of the Lala deposit. This study uses trace element compositions of magnetite to examine the nature and origin of the ore-forming fluids. The magnetite has variable concentrations of Ti, Al, Mg, Mn, Si, V, Cr, Ca, Co, Ni, Sc, Zn, Cu, Mo, Sn, and Ga, which are thought to have been controlled mainly by fluid compositions and/or intensive parameters (e.g., temperature and oxygen fugacity (fO2)). Fluid-rock interaction and coprecipitating mineral phases appear to be less important in controlling the magnetite compositions. Magnetite grains in the Fe-oxide stage of the Lala and Dahongshan deposits have comparable trace element compositions and were likely precipitated from chemically similar fluids. High Ni contents of magnetite in both deposits, coupled with previous isotopic data and the fact that the two deposits are spatially associated with coeval mafic intrusions, strongly suggest that the ore-forming fluids were genetically related to the mafic magmas that formed the intrusions. Magnetite grains in the Fe-oxide stage of the Yinachang deposit have much lower V and Ni but higher Sn and Mo contents than those of the Lala and Dahongshan deposits and are thus thought to have precipitated from more oxidized and Mo-Sn-rich fluids that may have evolved from relatively felsic magmas. Magnetite grains from the Cu-sulfide and Fe-oxide stages of the Lala deposit are broadly similar in composition, but those in the Cu-sulfide stage have slightly higher Cu, Zn, and Mn and are thought to have crystallized from relatively low-temperature and Cu-Zn-Mn-rich fluids evolved from the fluids of the early Fe-oxide stage. Our results show that magnetite from the Fe-Cu deposits in the Kangdian Province, banded iron formation, Fe skarn deposits, diabase-hosted hydrothermal Fe deposits, and magmatic deposits has significantly different compositions. We propose that covariations of Co-Ni, Zn-Sn, and Co/Ni-Mn can be used to effectively discriminate different deposit types.

The factors and processes that control trace-element partitioning among co-crystallizing cumulus minerals in layered intrusions have long been controversial. Here we address this issue using new laser ablation ICP-MS trace element data for magnetite, ilmenite, and clinopyroxene from the Panzhihua layered intrusion in the Emeishan large igneous province, SW China. The cumulus minerals display strong Ni, Co, and Cr depletions, indicative of parental magmas low in concentration of these elements probably due to prior sulfide removal and the fractionation of chromite or Cr-magnetite in a staging magma chamber at depth. Both magnetite and clinopyroxene show cyclical variations in some transition elements (e.g., Cr, V, and Ni) along the stratigraphic section. The average concentrations of these transition elements in magnetite are positively correlated with those in clinopyroxene, likely resulting from co-crystallization of magnetite and clinopyroxene. The incompatible element (e.g., Zr, Hf, and Nb) concentrations of the cumulus minerals from the Lower Zone are highly variable compared to those of the Middle and Upper Zones. These large variations in trace element compositions are attributed to a “trapped liquid shift” in the Lower Zone. Ilmenite crystals from the Panzhihua intrusion may have undergone extensive modification of transition elements during subsolidus re-equilibration with magnetite, leading to the decoupled variations of transition elements in ilmenite across the Lower Zone stratigraphy. Our study indicates that systematic trace element variations of the main cumulus mineral assemblage, rather than a single mineral, need to be considered to better constrain the magmatic differentiation and elemental fractionation of layered intrusions.

The Jinding Zn–Pb deposit, located in the Lanping basin in Northwest Yunnan Province, is the largest Zn–Pb deposit in China, and also probably the youngest sediment-hosted super giant Zn–Pb deposit in the world. Its genesis differs from the well-known major types of sediment-hosted Zn–Pb deposits. Based on mineral paragenesis and textures, there are two stages of mineralization: stage 1 that is typically characterized by fine-grained sulfide minerals (galena, sphalerite, pyrite and marcasite) disseminated in sandstones of the Lower Cretaceous Jingxing Formation (K 1 j), and massive sulfides in limestone breccias of the Paleocene Yunlong Formation (E 1 y); and stage 2 which mainly occurs as coarse-grained galena veins crosscutting stage 1 sulfides, and minor amounts of colloform sphalerite intergrown with galena. In situ sulfur isotopic analyses of galena, sphalerite and pyrite were determined by secondary ion mass spectrometry (SIMS), and showed highly variable δ 34 S values (− 42.1‰–7.7‰) of different ore types. Stage 1 mineralization has δ 34 S values from − 42.1‰ to − 10.2‰ with the majority ranging from − 26‰ to − 14‰. Stage 2 mineralization has higher δ 34 S values (− 8.3‰–7.7‰). Combined with the geological settings and mineral paragenesis, the sulfur isotopic data presented here suggest multiple sulfur sources (biogenic sulfur + evaporites) and formation mechanisms for reduced sulfur (H 2 S). H 2 S responsible for stage 1 sulfide precipitation was associated with bacterial sulfate reduction (BSR). However, H 2 S of stage 2 was likely derived from thermochemical sulfate reduction (TSR). The most reasonable scenario for the stage 1 mineralization is a metal-bearing brine mixing with an H 2 S-rich fluid, thereby causing rapid sulfide precipitation. Till the stage 2, the ore-forming fluid shifted to the meteoric water that infiltrated and reacted with evaporitic rocks, leached metals and transported them as sulfate- or sulfite-complexes to the Jinding dome where the oxidized sulfur was reduced by organic matters to H 2 S, leading to precipitation of metal sulfides. In contrast to other sulfide deposits in the Lanping basin, biogenic sulfur might have played a key role in the mineralization process, especially during the early stage of formation of the Jinding Zn–Pb deposit.

The positions of the CH4 Raman nu(1) symmetric stretching bands were measured in a wide range of temperature (from -180 degrees C to 350 degrees C) and density (up to 0.45 g/cm(3)) using high-pressure optical cell and fused silica capillary capsule. The results show that the Raman band shift is a function of both methane density and temperature; the band shifts to lower wavenumbers as the density increases and the temperature decreases. An equation representing the observed relationship among the CH4 nu(1) band position, temperature, and density can be used to calculate the density in natural or synthetic CH4-bearing inclusions. Copyright (C) 2014 John Wiley & Sons, Ltd.

The Baiyangping Cu–Ag polymetallic ore district is located in the northern part of the Lanping–Simao foreland fold belt, which lies between the Jinshajiang–Ailaoshan and Lancangjiang faults in western Yunnan Province, China. The source of ore-forming fluids and materials within the eastern ore zone were investigated using fluid inclusion, rare earth element (REE), and isotopic (C, O, and S) analyses undertaken on sulfides, gangue minerals, wall rocks, and ores formed during the hydrothermal stage of mineralization. These analyses indicate: (1) The presence of five types of fluid inclusion, which contain various combinations of liquid (l) and vapor (v) phases at room temperature: (a) H 2 O (l), (b) H 2 O (l) + H 2 O (v), (c) H 2 O (v), (d) C m H n (v), and (e) H 2 O (l) + CO 2 (l), sometimes with CO 2 (v). These inclusions have salinities of 1.4–19.9 wt.% NaCl equivalents, with two modes at approximately 5–10 and 16–21 wt.% NaCl equivalent, and homogenization temperatures between 101 °C and 295 °C. Five components were identified in fluid inclusions using Raman microspectrometry: H 2 O, dolomite, calcite, CH 4 , and N 2 . (2) Calcite, dolomitized limestone, and dolomite contain total REE concentrations of 3.10–38.93 ppm, whereas wall rocks and ores contain REE concentrations of 1.21–196 ppm. Dolomitized limestone, dolomite, wall rock, and ore samples have similar chondrite-normalized REE patterns, with ores in the Huachangshan, Xiaquwu, and Dongzhiyan ore blocks having large negative δCe and δEu anomalies, which may be indicative of a change in redox conditions during fluid ascent, migration, and/or cooling. (3) δ 34 S values for sphalerite, galena, pyrite, and tetrahedrite sulfide samples range from −7.3‰ to 2.1‰, a wide range that indicates multiple sulfur sources. The basin contains numerous sources of S, and deriving S from a mixture of these sources could have yielded these near-zero values, either by mixing of S from different sources, or by changes in the geological conditions of seawater sulfate reduction to sulfur. (4) The C–O isotopic analyses yield δ 13 C values from ca. zero to −10‰, and a wider range of δ 18 O values from ca. +6 to +24‰, suggestive of mixing between mantle-derived magma and marine carbonate sources during the evolution of ore-forming fluids, although potential contributions from organic carbon and basinal brine sources should also be considered. These data indicate that ore-forming fluids were derived from a mixture of organism, basinal brine, and mantle-derived magma sources, and as such, the eastern ore zone of the Baiyangping polymetallic ore deposit should be classified as a “Lanping-type” ore deposit.