Superlarge Deposits Research Articles

Research on Spatiotemporal Heterogeneity of the Impact of Earthquakes on Global Copper Ore Supply Based on Geographically Weighted Regression

The large and super large copper deposits worldwide are mainly distributed in the Pacific Rim and Gondwana metallogenic domains, and they are highly coupled with the spatial location of seismically active zones. Major copper-producing countries such as Chile are located in areas with high seismic activity. Earthquakes often cause copper mines to shut down, copper prices to soar, and even mining disasters, affecting the stable supply of global copper. In order to study the impact of earthquakes on the global copper ore supply, information on resource endowments, production, and earthquake data from the past 30 years are collected. This article mainly analyzes (1) the spatial correlation between earthquakes and copper mine projects, and the spatial characteristics of earthquakes’ impact on copper mine production, using correlation analysis and geographically weighted regression (GWR); (2) the impact of sudden earthquake events on the export volume and price of copper mines from the perspective of time, using the earthquake index constructed based on the magnitude of the earthquake, the depth of the epicenter, and the distance from the copper mine. The results indicate that the regions with high spatial correlation between copper mine projects and earthquakes are mainly located along the Pacific coast of South and North Americas. Earthquakes can lead to an increase in copper prices, but they will fall significantly in the short term. The impact of earthquakes on export volume generally has a delay period of 1–2 months, resulting in a short-term decrease in export volume. This article quantitatively evaluates the impact of earthquake risk on the supply chain from both spatial and temporal dimensions, providing reference for supply chain risk monitoring, risk impact assessment, and prediction. On the basis of the research results of this article, mineral resource management departments can quantitatively evaluate the spatiotemporal impact of natural risks such as earthquakes on the supply chain, adjust management policies in a timely manner, and improve the level of refined management of supply chain risks.

Whole-Rock Geochemistry and Mica Compositions in Lijiagou Pegmatite Spodumene Deposit, Western Sichuan, China

The Lijiagou pegmatite spodumene deposit, located in the middle of the Songpan–Garze Fold Belt and southeast of the Ke’eryin ore field, is a newly discovered super-large deposit. In order to reveal the metallogenic tectonic environment and evolution process of pegmatite, based on the study of the geological characteristics of pegmatite, we carried out a whole-rock geochemical analysis of Ke’eryin two-mica granite and Lijiagou pegmatite and carried out a detailed electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis of mica minerals in each zonal pegmatite. The results show that the Ke’eryin two-mica granite is mainly formed in the transition period from syn-collision to post-collision. After the end of the continental collision, the crust is squeezed and thickened in the post-collision extensional transition tectonic environment. Mica from the microcline pegmatite zone (MP) to the albite spodumene pegmatite zone (ASP) in pegmatite show different compositions and structural characteristics, with the evolution trend in the direction from muscovite to Li-bearing mica. The type of mica from MP to AP is mainly muscovite, and Li-bearing mica appears in ASP, which is secondary and metasomatic at the edge of primary muscovite. From MP to ASP, there was a negative correlation between Nb/Ta, K/Rb and the Li, Rb, and Cs contents of mica, while the contents of Li, Rb, Cs, and F in the Li-bearing mica of ASP increased sharply. This evidence illustrates that the favorable tectonic environment contributed to the formation of the Lijiagou pegmatitic spodumene deposit. Lijiagou pegmatite experienced the magmatic–hydrothermal evolution process and has a high degree of differentiation and evolution from MP to ASP, which gradually increased. Combined with the change in mica type, it is considered that ASP formed from the stage of magmatic transition to hydrothermal and was a hydrothermal environment, and Li, Rb, and Cs mainly began to enrich at the stage of magmatic–hydrothermal transition.

Metallogenic Age and Ore‐forming Material Sources of the Dahongshan Fe‐Cu Deposit, Yunnan Province: Insights from Molybdenite Re‐Os Dating and H‐O‐S‐Pb Isotopes

AbstractThe Dahongshan Fe‐Cu (‐Au) deposit is a superlarge deposit in the Kangdian metallogenic belt, southwestern China, comprising approximately 458 Mt of Fe ores (40% Fe) and 1.35 Mt Cu. Two main types of Fe‐Cu (‐Au) mineralization are present in the Dahongshan deposit: (1) early submarine volcanic exhalation and sedimentary mineralization characterized by strata‐bound fine‐grained magnetite and banded Fe‐Cu sulfide (pyrite and chalcopyrite) hosted in the Na‐rich metavolcanic rocks; (2) late hydrothermal (‐vein) type mineralization characterized by Fe‐Cu sulfide veins in the hosted strata or massive coarse‐grained magnetite orebodies controlled by faults. While previous studies have focused primarily on the early submarine volcanic and sedimentary mineralization of the deposit, data related to late hydrothermal mineralization is lacking. In order to establish the metallogenic age and ore‐forming material source of the late hydrothermal (‐vein) type mineralization, this paper reports the Re‐Os dating of molybdenite from the late hydrothermal vein Fe‐Cu orebody and H, O, S, and Pb isotopic compositions of the hydrothermal quartz‐sulfide veins. The primary aim of this study was to establish the metallogenic age and ore‐forming material source of the hydrothermal type orebody. Results show that the molybdenite separated from quartz‐sulfide veins has a Re‐Os isochron age of 831 ± 11 Ma, indicating that the Dahongshan Fe‐Cu deposit experienced hydrothermal superimposed mineralization in Neoproterozoic. The molybdenite has a Re concentration of 99.7–382.4 ppm, indicating that the Re of the hydrothermal vein ores were primarily derived from the mantle. The δ34S values of sulfides from the hydrothermal ores are 2‰–8‰ showing multi‐peak tower distribution, suggesting that S in the ore‐forming period was primarily derived from magma and partially from calcareous sedimentary rock. Furthermore, the abundance of radioactive Pb increased significantly from ore‐bearing strata to layered and hydrothermal vein ores, which may be related to the later hydrothermal transformation. The composition of H and O isotopes within the hydrothermal quartz indicates that the ore‐forming fluid is a mixture of magmatic water and a small quantity of water. These results further indicate that the late hydrothermal orebodies were formed by the Neoproterozoic magmatic hydrothermal event, which might be related to the breakup of the Rodinia supercontinent. Mantle derived magmatic hydrothermal fluid extracted ore‐forming materials from the metavolcanic rocks of Dahongshan Group and formed the hydrothermal (‐vein) type Fe‐Cu orebodies by filling and metasomatism.

RARE EARTH ELEMENT RESOURCE POTENTIAL OF SUPER-LARGE DEPOSITS IN EASTERN FENNOSCANDIA

Work has been carried out to assess the rare-earth potential of the main ore minerals -loparite, eudialyte and apatite of the Lovozersky and Khibinsky deposits. Super-large deposits of loparite and eudialyte are associated with the giant Lovozero intrusion (Eastern Fennoscandia, Kola Peninsula). There are a number of apatite deposits in the Khibiny complex. All these ores occupy a leading place in the structure of the raw material of Russia. The highest contents of the sum of rare earth metals are characteristic of loparite ores (the content of ΣREE in loparites is about 28 wt%), and light rare earths sharply prevail over heavy ones, the Ce/Yb ratio is about 78 000. The amount of REE in eudialites is about 2 by mass%. A remarkable feature of eudialyte ores is the high concentrations of the heavy REE group, the Ce/Yb ratio is about 14. The apatites of the Khibiny deposits occupy an intermediate position: the Ce/Yb ratio is 680, and the average concentration of the REE sum is 0.9 wt%. The conditions of formation of apatite, loparite and eudialyte ores are considered.

Mineralogical Characteristics of Baima Vanadium Titanomagnetite during Magnetic Separation Upgrading

The Baima vanadium titanomagnetite deposit, located in the Panzhihua-Xichang (Panxi) metallogenic belt in China, is one of the super-large deposits in the region. The titanomagnetite upgrading process involves grinding the raw ore followed by magnetic separation. To determine the processing characteristics of the ore and assess the upgrading process, this study employs various methods and techniques, including the X-ray fluorescence spectrometer (XRF), chemical element analysis, the electron probe microanalyzer (EPMA), and the advanced mineral identification and characterization system (AMICS). The results show that the Fe grades in the upgraded raw ore, upgraded concentrate, and upgraded tailings are 55.68%, 57.89%, and 15.62%, respectively. After upgrading, the titanomagnetite content increased from 77.41% to 82.10%, and the Fe distribution in titanomagnetite also increased from 91.05% to 93.14%. In the upgraded raw ore, titanomagnetite particles followed a normal distribution, with 50.44% in the 38–74 μm range. In the upgraded concentrate, titanomagnetite was concentrated in the 19–38 μm range. Based on EPMA data, the theoretical Fe grade in titanomagnetite was calculated to be 65.08%, indicating the potential for further improvement through the upgrading process. This study elucidates the mineralogical characteristics during the vanadium titanomagnetite upgrading, providing a theoretical basis to further enhance the Fe recovery rate.

Rare Earth Element Resource Potential of Super-Large Deposits in Eastern Fennoscandia

This work has been carried out to assess the rare-earth potential of the main ore minerals of the Lovozero and Khibiny deposits. The loparite and eudialyte deposits are associated with the giant Lovozero intrusion (Eastern Fennoscandia, Kola Peninsula). There are several deposits of apatite–nepheline ores in the Khibiny complex. All these ores take the leading position in the structure of the raw material base of Russia. The highest contents of the sum of rare earth metals (REMs) are typical of loparite ores (the content of ΣREE in loparites is about 28 wt %), light rare earths sharply dominate over heavy ones (the Ce/Yb ratio is about 78000). The sum of REEs in eudialytes is about 2 wt %. A remarkable feature of eudialyte ores is the high concentration of the heavy REM group (the Ce/Yb ratio is about 14). The apatites of the Khibiny deposits occupy an intermediate position: the Ce/Yb ratio is 680, and the average concentration of the REE sum is 0.9 wt %. The conditions of formation of apatite, loparite, and eudialyte ores are considered.

Sources of Metals for the Rudny Altai VMS Deposits: Results of High-Precision MC-ICP-MS Lead Isotope Study

The Rudny Altai metallogenic province, which is concordant to the structures of the eponymous terrane and located in the Central Asian orogenic belt (CAOB), is one of the largest volcanic massive sulfide (VMS) provinces in the world. Lead isotopic composition of galena (61 samples in total) was measured for the first time with high accuracy (±0.02%, SD) for 20 sulfide base metal deposits representing the dominant Kuroko type in the Rudny Altai. They are enclosed in the Early–Middle Devonian volcano-sedimentary sequence in association with volcanic rocks of the bimodal basalt-rhyolite series. We studied the large and superlarge deposits of this type: Ridder-Sokol’noe, Tishinskoe, Novo-Leninogorskoe, Zyryanovskoe, Zmeinogorskoe, and Korbalikha. In the province, the isotope ratios 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb vary within narrow limits. At average values of 206Pb/204Pb = 17.820, 207Pb/204Pb = 15.517 and 208Pb/204Pb = 37.669, the root mean square variations (variation coefficient, %) are 0.22, 0.038 and 0.063% respectively. Even more homogeneous composition is observed within ore districts of the province (0.054, 0.012 and 0.020%) and especially within deposits (0.025, 0.010 and 0.013%), where the scale of variations of lead isotope ratios reaches their measurement error (±0.02%). The lead isotopic composition in the province shows no isotopic “signatures” of juvenile (asthenospheric) origin. The evolutionary characteristics of the lead source (its depletion in uranium, the old model Pb-Pb age, and moderate values of the µ2 parameter) together with the persistent isotopic composition allow us to regard the lithospheric mantle consisting of metasomatized and recycled rocks as its source. This source was of regional significance, chemically (U-Th-Pb) and isotopically (Pb-Pb) homogeneous, and common for all deposits. Among other CAOB terranes, including the Chinese Altai, the 206Pb, 207Pb and 208Pb isotopes in the ore lead of the Rudny Altai terrane have the least radiogenic composition. The previously noted (Chiaradia et al., 2006) systematic decrease of radiogenic isotope content in the lead of ores and rocks of the CAOB terranes from the southwest to the northeast correlates with a decrease in the lower crustal contribution in the same direction in their composition, where fragments and blocks of Precambrian crust are also involved. The peculiarity of the Pb isotopic composition of the Rudny Altai terrane is largely determined by the absence of Precambrian crustal blocks in its composition.

Cd isotope constraints on metal sources of the Zhugongtang Zn–Pb deposit, NW Guizhou, China

The Sichuan–Yunnan–Guizhou metallogenic province (SYGMP) includes > 400 Zn − Pb deposits and prospects, eight of which are large-scale deposits with large reserves of critical metals such as Cd and Ge, including the Huize Zn − Pb − Cd − Ge and Daliangzi Zn–Pb–Ge–Cd deposits. The newly discovered Zhugongtang Zn − Pb deposit is a super-large deposit with Zn–Pb reserves of > 3 Mt. Its geochemical features are similar to those of the Huize deposit, with similar sulfide δ34S values and concentrations of critical elements in sphalerite (e.g., Cd and Ge). However, the two deposits have different host strata, and it remains unclear as to whether they have similar oregenesis. In this study, δ114/110Cd values and major- and trace-element compositions of sphalerites collected from a drill-core and tunnels of the Zhugongtang deposit were determined in an investigation of metal sources. Drill-core samples were impure and exhibited strong correlation (R2 = 0.89) between Zn and Cd contents. For samples from mining tunnels, the Cd and Fe contents of selected sphalerites were positively correlated, especially yellow sphalerites (R2 = 0.76). Cadmium is likely hosted in sphalerite by the substitution mechanism of (Fe2+, Cd2+) ↔ Zn2+. The δ114/110Cd values of all samples ranged from − 0.43 ‰ to 0.06 ‰. Based on Zn/Cd ratios, and excluding geochemical processes that may have caused the variable Cd isotopic compositions, we suggest that the metal sources of the deposit were derived from the mixing of sedimentary and basement rocks. This model is supported by the strong relationship between the δ114/110Cd and 1/Cd values of sphalerites from 11 typical Zn–Pb deposits in the SYGMP (R2 = 0.81). The quantification of metal contributions of source rocks indicates that deposits derived mainly from sedimentary rocks generally have relatively low sphalerite Ge contents and small Ge reserves, whereas those derived mainly from basement rocks have higher Ge contents and larger Ge reserves. This study provides a new model for explaining the enrichment of critical metals in Zn–Pb deposits of the SYGMP, thus extending the applications of Cd isotopes in hydrothermal systems.

Genesis of the Danping bauxite deposit in northern Guizhou, Southwest China: Constraints from in-situ elemental and sulfur isotope analyses in pyrite

The super large bauxite deposit known as the Danping deposit is hosted in the Dazhuyuan formation, Lower Permian, and is located in northern Guizhou (Southwest China). The geochemical signatures of five generations of pyrite from Danping have been identified, and their genesis has been constrained by analyzing their geochemical signatures. Oolitic pyrite (Py-O), which has two sub-generations, occurs in the upper part of the oolitic bauxite. Typically, Py-O2 has a core and rim structure, where the core may contain altered primary Py-O1. While Py-M appears as occurs in the form of interstitial material in the lower part of the oolitic bauxite, Py-C is cubic in shape and is reported in the earthy bauxite. Moreover, Py-Q is found in the Qixia formation. Py-M has a Co/Ni ratio of ∼ 1 and a δ34SV-CDT value of ∼ 0 ‰, thus suggesting a magmatic hydrothermal origin. The primary Py-O1 has a uniform geochemical composition. The reformed Py-O1 and the core of Py-O2 have considerably lower δ34S values of −19.15 ‰ to −4.72 ‰, indicating that a brief pulse of seawater injection can result in the replacement of Py-O1 and the formation of Py-O2. Py-M, Py-O and Py-Q all have positive Ce anomalies, while Py-C has negative Ce anomalies. These contrasting characteristics demonstrate that the original aluminous rock series was largely deposited in an oxidic environment, while the earthy bauxite was formed in a reducing environment. Lithium, Sc and Ga are positively correlated with one another, reflecting their similar geochemical behavior during sedimentary–weathering processes. Py-M has higher contents of Li, Sc and Ga, implying that magmatic fluids contributed to the presence of critical metals even in the weathering conditions.

Zircon U-Pb Ages and Geochemistry of the Granite in the Xintianling Tungsten Deposit, SE China: Implications for Geodynamic Settings of the Regional Tungsten Mineralization

The Xintianling tungsten deposit is a super-large deposit in the Nanling tungsten–tin mineralization belt, which is genetically associated with the early-stage hornblende-biotite monzonitic granite of Qitianling pluton. The orebodies predominantly occur as veins and lenses within skarn rocks between Xintianling granite and limestone (Shidengzi group). In this work, whole-rock major and trace elements and zircon U–Pb ages of the Xintianling granite were studied in an attempt to investigate the geochronological framework, petrogenesis, tectonism, and metallogenesis with regard to the deposit. The petrographic and geochemical analyses indicated that the Xintianling granite consists of three intrusive units of medium- and coarse-grained biotite granite, fine-grained biotite granite, and granite porphyry, of which the biotite granite was strongly associated with mineralization. Biotite granite rocks are highly K-calc-alkaline and weakly peraluminous, with A/CNK ratios ranging from 0.99 to 1.05. Late-granite porphyry is aluminum-supersaturated with a high evolution degree, whose geochemical characteristics suggest that it is either an I- or S-type granite. LA-ICP-MS zircon U-Pb dating revealed that medium- and coarse-grained biotite granite (162.3 ± 1.2 Ma, MSWD = 1.3), fine-grained biotite granite (161.8 ± 1.3 Ma, MSWD = 1.8), and granite porphyry (154.3 ± 1.6 Ma, MSWD = 2.4) formed in the late Jurassic. The emplacement of the Qitianling A-type granite and associated tungsten-tin polymetallic mineralization is a continuous evolution process, and they are products of the large-scale mineralization of the Nanling in the middle–late Jurassic (150–160 Ma). Under the tectonic setting of the Mesozoic lithospheric extension, asthenosphere upwelling along deep-fault, intensive mantle–crust interaction processes probably provide not only the high heat flow, but also partly mantle-derived material for large-scale W-Sn-polymetallic mineralization in this area.

Apatite Fission Track Thermochronology of Granite from Duobaoshan Porphyry Cu (Mo) Deposit, Northeast China: Implications for Cooling History and Ore Preservation

The Duobaoshan Cu (Mo) deposit is one of the oldest super large porphyry deposits in the eastern part of the Central Asian orogenic belt. Although ore-forming processes have been extensively concerned, the post-mineralization ore preservation state was poorly focused on. In order to improve the ability of prospecting forecast, it is necessary to consider both deposit formation and deposit preservation. Here, we reported apatite fission track (AFT) data for the Duobaoshan porphyry copper deposits in the belt to reveal the cooling and exhumation history and evaluate ore preservation. The results show that the rapid cooling of the ore-hosting rock body occurred later than the surrounding rock body. The rapid cooling of the surrounding granodiorite occurred between 82 and 72 Ma, with the exhumation depth of 2.33–3.11 km and the exhumation rate of 0.25 mm/a, whereas the ore-hosting granodiorite porphyry was rapid cooling between 71.8 and 50.2 Ma, with the exhumation depth of 2.99–3.86 km and the exhumation rate of 0.22 mm/a. This differential exhumation and cooling event provide favorable geological conditions for the preservation of the ore body.

Mineralogical Characterization of Manganese Oxide Minerals of the Devonian Xialei Manganese Deposit

The Guangxi Zhuang Autonomous Region is an important manganese ore district in Southwest China, with manganese ore resource reserves accounting for 23% of the total manganese ore resource reserves in China. The Xialei manganese deposit (Daxin County, Guangxi) is the first super-large manganese deposit discovered in China. The Mn oxide in the supergene oxidation zone of the Xialei deposit was characterized using scanning electron microscopy (SEM), energy spectrometer (EDS), transmission electron microscopy (TEM, HRTEM), and X-ray diffraction analysis (XRD). The Mn oxides have a gray-black/steel-gray color, a semi-metallic-earthy luster, and appear as oolitic, pisolitic, banded, massive, and cellular textures. Scanning electron microscopy images show that the manganese oxide minerals are present as fine-spherical particles with an earthy surface. TEM and HRTEM indicate the presence of oriented bundled and staggered nanorods, and nanopores between the crystals. The Mn oxide ore can be classified into two textural types: (1) oolitic and pisolitic (often with annuli) Mn oxide, and (2) massive Mn oxide. Pyrolusite, cryptomelane, and hollandite are the main Mn oxide minerals. The potassium contents of cryptomelane and pyrolusite are discussed. The unit cell parameters of pyrolusite are refined.

Geochemistry of Super-Large Deposits of Eastern Fennoscandia (Kola Peninsula)

Geochemistry of Super-Large Deposits of Eastern Fennoscandia (Kola Peninsula)

Metallogenic model of the Shuangjianzishan Ag-Pb-Zn district, Northeast China: Revealed from integrated geophysical investigation

The Shuangjianzishan deposit in Inner Mongolia is a typical Ag-Pb-Zn deposit of the southern Great Xing’an Range. Proven reserves of Ag, Pb, and Zn in this deposit have reached the scale of super-large deposits, with favorable metallogenic conditions, strong prospecting signs, and high metallogenic potential. This paper reports a study involving integrated geophysical methods, including controlled-source audio-frequency magnetotelluric, gravity, magnetic, and shallow-seismic-reflection methods, to determine the spatial distribution of ore-controlling structures and subsurface intrusive rock for a depth range of <2000 m in the Shuangjianzishan ore district. The objective of this study is to construct a metallogenic model of the ore district and provide a scientific basis for the exploration of similar deposits in the deep and surrounding regions. We used three-dimensional inversion for controlled-source audio-frequency magnetotelluric data based on the limited memory quasi-Newton algorithm, and three-dimensional physical-property inversion for the gravity and magnetic data to obtain information about the subsurface distribution of ore-controlling structures and intrusive rocks. Under seismic reflection results, regional geology, petrophysical properties, and borehole information, the geophysical investigation shows that the Dashizhai group, which contains the main ore-bearing strata in the ore district, is distributed within a depth range of <1239 m, and is thick in the Xinglongshan ore block and the eastern part of the Shuangjianzishan ore block. The mineralization is spatially associated with a fault system characterized by NE-, NW-, and N-trending faults. The magnetic and electrical models identify large, deep bodies of intrusive rock that are inferred to have been involved in mineralization, with local shallow emplacement of some intrusions. Combining the subsurface spatial distributions of ore-bearing strata, ore-controlling faults, and intrusive rock, we propose two different metallogenic models for the Shuangjianzishan ore district, which provide a scientific basis for further prospecting in the deep regions of the ore district and surrounding areas.

Redox-controlled antimony isotope fractionation in the epithermal system: New insights from a multiple metal stable isotopic combination study of the Zhaxikang Sb–Pb–Zn–Ag deposit in Southern Tibet

Redox reactions, biological processes, evaporation and precipitation processes, adsorption, and Rayleigh distillation mechanisms have been proposed to account for the fractionation of antimony (Sb) isotopes in natural materials. However, only one paper was published to support and characterize the Rayleigh distillation induced Sb isotopic fractionation in a hydrothermal system. Therefore, the Sb isotopic fractionation mechanism research in the epithermal system is still negligible, which severely restricts future application. The Zhaxikang Sb–Pb–Zn–Ag deposit is the only super-large deposit within the North Himalayan Metallogenic Belt (NHMB), which comprises two episodes of mineralization (First episode: Pb–Zn mineralization, Stages 1 and 2; Second episode: Sb mineralization, Stages 3 to 6). Herein, we measured the δ123SbNIST 3102A values of stage 4 sulfosalt minerals and stage 5 stibnite from the Zhaxikang Sb–Pb–Zn–Ag deposit, to resolve the fractionation direction and relative magnitude of Sb isotopes caused by these aforesaid geologically prominent mechanisms in the epithermal systems with an auxiliary investigation of Fe–Cu isotopes. The second episode of Sb-containing hydrothermal fluid has leached metals (e.g., Pb, Ag, Fe, Cu) from pre-existing Pb–Zn orebodies, to initiate the formation of stage 4 sulfosalt minerals. According to XPS (X-ray Photoelectron Spectroscopy) analyses, the Cu isotopic variation of stage 4 bournonite (0.08‰ – 0.89‰) must be controlled primarily by the reduction reaction (Cu2+ + e− → Cu+) during leaching and precipitation. Keeping in mind a good linear correlation between δ123Sb and δ65Cu values (R2 = 0.99) for bournonite, the same mechanism was used to decipher the variation in δ123Sb values (0.10‰ – 0.48‰) of bournonite (Sb5+ + 2e− → Sb3+). Abundant native sulfur within the orefield allowed for the overall reaction equation of CuFeS2 + FeS2 + PbS + Sb5+(aq) = CuPbSbS3 + Fe2+(aq) + 2S to describe the bournonite formation. Accordingly, the Sb isotopic variations (−0.27‰ to 0.48‰) of Sb-bearing minerals (boulangerite, bournonite and stibnite) were empirically attributed to redox reactions. The Rayleigh distillation model indicated that the observed fractionation was most likely induced by redox reactions, while the related theoretical calculations revealed a great antimony exploration potential in deeper parts of the orefield. Overall, the Sb isotopes could be used to identify redox changes in the epithermal system, and exhibit great potential in tracing metal sources, monitoring fluid evolution and ore formation, and providing insights into mineral exploration.

Cadmium isotopic constraints on metal sources in the Huize Zn–Pb deposit, SW China

The Sichuan–Yunnan–Guizhou (SYG) Zn–Pb metallogenic zone in SW China contains >400 carbonate-hosted hydrothermal Zn–Pb deposits. Some of these, such as the Huize, Tianbaoshan, and Daliangzi deposits, are super-large deposits with significant reserves of Cd, Ge, and Ag. However, the sources of these metals remain controversial. This study investigated the Cd isotopic geochemistry of the Huize deposit, the largest Zn–Pb deposit in the SYG area. Sphalerites formed at three stages in the deposit have different colors: black or dark brown (Stage I), red (Stage II), and light-yellow (Stage III). The δ114/110Cd values of the sphalerites are in the order Stage III < Stage I < Stage II. Kinetic isotopic fractionation is likely the key factor causing the lower δ114/110Cd values in the early formed Stage I sphalerites than in later-formed Stage II sphalerites, with cooling of ore-forming fluids being responsible for the still lower values of the Stage III sphalerites. In galena, the δ114/110Cd values are inversely correlated with Cd contents and tend to be higher in high-Zn galena. We speculate that Cd isotopic fractionation was significant during the precipitation of sphalerite and galena, with light Cd isotopes being enriched in galena rather than sphalerite. Comparison of the Cd isotopic signatures and Zn/Cd ratios of different endmembers suggests that the δ114/110Cd values and Zn/Cd ratios of sphalerite from the Huize deposit, as well as other large-scale deposits from the SYG area, are lie in those range of Emeishan basalts and sedimentary rocks and the mean δ114/110Cd values of these deposits show good negative correlation with 1/Cd, suggesting that the ore-forming materials of these deposits were derived from the mixing of Emeishan basalts and sedimentary rocks. This study demonstrates that Cd isotopes can be useful proxies in elucidating ore genesis in large Zn–Pb deposits.

Analysis of Tectonic Stress Characteristics of the Bainiuchang Silver-Lead Polymetallic Mining Area, Yunnan Province, SW China

The southeastern of Yunnan metallogenic belt is an area with many large- super large deposits in the Metallogenic Province of South in China. The mineral deposits in the area are densely distributed and the geological structure is complex. This article studies the joints (cracks) of the super large bed in the Bainiu factory in this area, a total of 21 joint observation points, 685 groups of occurrence structural surfaces were observed, and uses Dips software to analyze the joints (fissures) in the mining area. It is concluded that there are three periods of tectonic stress in the mining area, which are closely related to the mineralization, there are North North West-South South East, North East-South West, and South-North.

Sulfur isotopic characteristics of the Zhaxikang Sb–Pb–Zn–Ag deposit in southern Tibet

The Zhaxikang Sb–Pb–Zn–Ag deposit is the only super-large deposit in the North Himalayan Metallogenic Belt, but its genesis is debated. Genetic models include hot springs, magmatic-hydrothermal fluids and sedimentary exhalative overprinted by hydrothermal fluids. Here, we present sulfur isotopic data to constrain the genetic models for this deposit. The δ 34SV-CDT values of sulfides in the first pulse of mineralisation range from 7.8 to 12.2‰ (average = 10.7‰), and in the second pulse of mineralisation have lower δ 34S values of 4.5–11.3‰ (average = 8.5‰), suggesting the sulfur source for the first pulse of mineralisation is mainly seawater sulfur mixed with some mantle-derived sulfur, whereas the second pulse of mineralisation originated from mantle-derived sulfur and sulfur from earlier formed sulfides and wall rocks. Together with previously published Fe–Zn–Cd isotope evidence for the Zhaxikang deposit and regional S isotopic and geochronological data, the new data suggest that the first pulse of mineralisation is related to multiple seafloor volcanic events during the synsedimentary period (220–130 Ma) with submarine hydrothermal sedimentation (metasomatism) genesis that is overprinted by the second pulse of mineralisation associated with the magmatic-hydrothermal activity during the post-collision period (25 Ma to now). KEY POINTS The Zhaxikang Sb–Pb–Zn–Ag deposit, a super-large deposit in the North Himalayan Metallogenic Belt, is the product of overprinting hydrothermal events. The first pulse of mineralisation is related to multiple seafloor volcanic events and is overprinted by a second pulse of mineralisation associated with the magmatic-hydrothermal activity. Sulfur isotope analyses show the first pulse achieved equilibrium during sulfide crystallisation, but kinetic Rayleigh fractionation induced sulfur isotope variations for the second pulse of mineralisation.

Gold deposition and resource potential of the Linglong gold deposit, Jiaodong Peninsula: Geochemical comparison of ore fluids

The Linglong gold deposit is a super large deposit in the Linglong goldfield, northern Jiaodong Peninsula. The orebodies consist of hundreds of auriferous quartz veins that surrounded by relatively narrow K-feldspar alteration halos. Four mineralization stages have been identified on the basis of cross-cutting relationships, and mineralogical and textural characteristics: milky quartz–pyrite (stage 1), grey-white quartz–pyrite (stage 2), quartz–pyrite–base-metal sulfide (stage 3), and quartz–carbonate (stage 4). Native gold was mainly deposited in stages 2 and 3. Petrographical and microthermometric studies on quartz from stages 2 and 3 ores reveal three types of fluid inclusions associated with gold mineralization: Type 1 H2O–CO2–NaCl ± CH4 inclusion that consisting FIA 1 and represent a homogeneous fluid trapped at the same pressure and temperature; coexisting Type 2a H2O-rich H2O–CO2–NaCl ± CH4 and Type 2b CO2-rich H2O–CO2–NaCl ± CH4 inclusions that constitute FIA 2 and are interpreted to be products of a heterogeneously trapped fluid. The ore-forming fluids belong to a H2O–NaCl–CO2 ± CH4 system with medium temperatures (~290–340 °C), low salinity (~4–7 wt% NaCl eq.), and are CO2-rich (~15% mol) with minor CH4 (~2–5% mol). The δD–δ18O values of ore-forming fluids vary from −63 to −57‰ and 6.0‰ to 9.3‰, respectively, overlap both the magmatic and metamorphic fluid fields. The δ34S values of hydrothermal pyrite have a narrow range from 5.6‰ to 7.9‰, and are within the ranges of Neoarchean Jiaodong Group, and Mesozoic Linglong granite, Guojialing granitoid and intermediate–basic dikes. Combined with H–O–S isotope data, fluid inclusions compositions, and regional geological events, the ore-forming fluids may have a metamorphic-dominate origin, but a mantle or crustal contribution cannot be excluded. Fluid immiscibility played a major role, and fluid-wallrock interaction may be a subordinate reason for gold deposition in Linglong. The stage 2 quartz grains contain more FIAs 2 and volatiles than those in stage 3 quartz, indicating a more extensive fluid-immiscibility process which has a positive-correlated higher gold grade. Based on the data of FIAs 2, the P–T conditions of gold depositions generally range from 242 to 54 MPa and 348 to 269 °C, with a depth of metallogenesis of 5.4–9.0 km. Considering the depth of regional post-ore exhumation has been calculated as about 5–7 km, the space with deep gold exploration is expectable at Linglong.

Isotope geochemistry of Zn, Pb and S in the Ediacaran strata hosted Zn-Pb deposits in Southwest China

The Sichuan–Yunnan–Guizhou (SYG) area is a world-class Zn-Pb metallogenic zone and contains over four hundred of carbonate-hosted hydrothermal Zn-Pb deposits, six of which are super large-scale deposits with significant sources of Cd, Ge, and Ag, including the Huize, Wusihe, Xiaoshifang, Maozu, Tianbaoshan and Daliangzi deposits. Although previous studies focused fully on these deposits, the ore genesis of which are still in controversial. Interestedly, four of those super large scale deposits are hosted in the Ediacaran Dengying Formation, including the Maozu, Wusihe, Tianbaoshan and Daliangzi deposits. Based upon previous studies, we investigate the extent, causes and consequences of Zn and Pb isotope signatures at hand specimen scale and ore genesis of the Daliangzi and Tianbaoshan deposits, associated with published data for the Wusihe deposit. Lead isotope ratios, coupled with published data, demonstrate that Pb in the studied deposits was predominantly derived from two components: basements and sedimentary rocks. Meanwhile, a strong positive linear correlation between δ66Zn and δ34SCDT values was observed in hand specimen D-2084, suggesting the variations may be resulted by fluid mixing. Furthuremore, the Zn isotope and Cd/Zn dataset from the Tianbaoshan, Daliangzi and Wusihe deposits defines a logarithmic curve (R2 = 0.82), which, to our knowledege, is firstly reported and lies between two indentified components: a low Cd/Zn end-member with high δ66Zn values and a high Cd/Zn end-member with low δ66Zn values. Based upon previous studies, we suggest that Zn and Pb in the Wusihe and Tianbaoshan deposits were predominantly derived from basements and Ediacaran sediments; in contrast, Zn and Pb in the Daliangzi deposit were predominantly derived from Ediacaran sediments and upper sedimentary rocks, but we cannot rule out metal contributions of the basements. Furthermore, we suggest that fluid mixing is more propreate to better explain Zn isotope signatures in the studied deposits.In summary, Zn and Pb isotope ratios reflect similar ore genesis and metal sources of the Daliangzi, Tianbaoshan and Wusihe Zn-Pb deposits in the SYG area. The application to the studied deposits with the discovery of Zn, S and Pb isotope compositions for sulfides indicates the potential of Zn isotope, combined with Cd/Zn raito, as new geochemical tracers, which may be useful for distinguishing the metal sources in large hydrothermal systems as suggested previously.