Pb Zn Research Articles

Cadmium isotope fractionation in a S-type granite related large magmatic–hydrothermal system

Granite-associated deposits are one of the important ore types in the Earth’s crust and can dominantly be subdivided into S-, I- and A-type granite-related deposits with different mineralization elements and isotopic signatures (e.g., sulphur and boron). The object of this study is to investigate whether Cd isotopic difference exists between I- and S-type granite-related deposits, and to provide new insights on geochemical behavior of Cd in such systems that have not been well constrained. The Dulong deposit in southwest China is a world-class skarn-type polymetallic Zn–Sn–In deposit that is thought to be genetically related to the emplacement of the highly fractionated S-type Laojunshan granite. The extremely negative δ114/110Cd values of sulfides (−0.82 ‰ to −0.42 ‰) within the Dulong deposit are all lower than those of sulfides from other Zn–Pb ore deposits globally. In comparison, representative sphalerites from I-type granite-related deposits yield heavier Cd isotopic compositions relative to the samples from the Dulong deposit. The Laojunshan granite samples are enriched in light Cd isotopes and have δ114/110Cd values that range from −0.73 ‰ to −0.40 ‰, overlapping with the δ114/110Cd values of sphalerite within the Dulong deposit and suggesting that the Cd in the deposit was derived from the Laojunshan granite. Similarly, I-type granite-related deposits elsewhere have Cd isotopic compositions that are similar to mafic–intermediate igneous rocks, suggesting little or no Cd isotopic fractionation took place during the magmatic–hydrothermal processes that formed these deposits. These results suggest that geochemical signatures of metal sources are the most likely control on Zn/Cd ratios and δ114/110Cd values of sulfides in these deposits, with different mineral deposit types having different Zn/Cd ratios and δ114/110Cd values. In summary, Cd isotopes provide a potentially effective tool for discriminating between different types of hydrothermal system and may also be useful in the investigation of granite petrogenesis.

Genesis of Pb–Zn-Ag-Sb mineralization in the Tethys Himalaya, China: Early magmatic-hydrothermal Pb–Zn(-Ag) mineralization overprinted by Sb-rich fluids

Genesis of Pb–Zn-Ag-Sb mineralization in the Tethys Himalaya, China: Early magmatic-hydrothermal Pb–Zn(-Ag) mineralization overprinted by Sb-rich fluids

Pyrite geochemical fingerprinting on skarn ore-forming processes: A case study from the Huangshaping W–Sn–Cu–Pb–Zn deposit in the Nanling Range, South China

Pyrite geochemistry has been extensively used to reveal ore-forming processes in diverse ore deposits, but its application in skarn systems is not well understood. The Huangshaping deposit in the Nanling Range (South China) uniquely develops W–Sn–Pb–Zn and Cu–Pb–Zn skarn mineralization systems, and both two systems have formed multi-types of pyrite, which provides a good window to reveal the mineralization histories of different skarn systems using pyrite trace element geochemistry. In the Cu–Pb–Zn system, texturally homogeneous Py1 mainly occurs in calcite veins within the host rock, whereas texturally homogeneous Py2 in the calcite-sulfide stage mainly occurs in skarn orebodies. Py3 in the siderite-sulfide stage replaces Py2 and commonly develops abundant pores or fractures, resembling the “bird's eye” texture. In the W–Sn–Pb–Zn system, Py4 in calcite veins can be divided into the oscillatory-zoned Py4a and irregular Py4b under BSE, and Py4b commonly replaces Py4a as veins or overgrowth. Texturally homogeneous Py5 in the calcite-sulfide stage occurs in skarn orebodies and is replaced by Py6 with a “bird's eye” texture in the siderite-sulfide stage.In the Cu–Pb–Zn system, Py1 may have formed by fluid cooling during its ascent along the hydraulic fractures indicated by its enrichment of Co, Ni, As, Sb, and Tl, whereas Py2 is likely formed under higher temperature and pH conditions caused by intense fluid-rock interactions evidenced by its depletion of Co, Ni, As, Sb, and Tl as well as its enrichment of Zn and Ag. In the W–Sn–Pb–Zn system, Py4b has higher contents of Co, Ni, As, Sb, and Tl than Py4a and similar contents of Ag, Zn, and Mo with Py4a, suggesting that decreasing temperature may have controlled the formation of Py4b. Py5 is featured by the depletion of As, Sb, Tl, and Mo as well as the enrichment of Zn and Ag, indicating that Py5 is likely formed under higher temperature and pH conditions resulting from the intense fluid-rock interactions. Marcasite replaces pyrrhotite and then is replaced by pyrite may be an important precipitation mechanism for pyrite with a “bird's eye” texture (Py3 and Py6) in both two skarn systems at Huangshaping. This study demonstrates that fluid-rock interaction is an important mechanism for sulfide precipitation at Huangshaping, which shows that pyrite geochemistry has good potential to reveal mineralization histories in skarn systems.

Application of portable multi-component gas analyzer to mineral exploration in semi-arid steppes of northern China: A case study from the Qinjiaying Ag–Pb–Zn prospect

Soil gases, particularly sulfur gases, have not been widely used in mineral exploration due to their high mobility and reactivity. However, our team developed a portable multi-component gas analyzer (PMGA) capable of on-site and real-time measurement of H2S, SO2, CH4, and CO2 concentrations in soil gas. This study showcases the applicability and effectiveness of PMGA in the geochemical exploration of concealed ore deposits in the Qinjiaying Ag–Pb prospect in semi-arid steppes. Comparison tests between different analyzers and periods were conducted in the Qinjiaying Ag–Pb prospect. The results showed that PMGA has high stability, consistency, and reproducibility. Then, soil gas geochemical surveys were carried out by applying PMGA along eight prospecting lines, with three prospecting lines passing through the known mineralized zone and the remaining five prospecting lines focusing on the covered areas. Three composite anomalies of H2S, SO2, CH4, and CO2 were identified. The No. 1 soil gas anomaly corresponds well to the known No. I mineralized zone. The No. 3 gas anomaly is characterized by large-scale and strong multi-gas anomalies, indicating the presence of great prospecting potentials. Finally, drilling verification revealed a medium-sized Ag–Pb–Zn deposit in the No. 3 gas anomaly. The results demonstrate that PMGA is a powerful tool for mineral exploration in the study area. This successful practice provides a paradigm for applying PMGA in mineral exploration in semi-arid steppes.

Metals pre–enrichment during the syn–sedimentary period of Mengxing Pb–Zn Deposit, western Yunnan, SW China: Evidence on LA–ICP–MS trace elements and S isotopes of lamellar sphalerite

The Mengxing Pb–Zn deposit, which contains up to 1.02 Mt of Pb + Zn metal with an average Pb + Zn grade of ca. 12.13 %, is a representative of sedimentary–reworked deposit in western Yunnan. The orebodies, which are strata–bound and veined, occur in the Silurian Shangrenheqiao formation. The mineralization process has been divided into sedimentary stage and hydrothermal stage. Previous research has primarily focused on the economic ores enriched during the hydrothermal stage. However, the formation of syn–sedimentary ore, responsible for metal pre–enrichment, has been largely ignored. To solve the issue above, the in–situ trace elements and mapping, as well as in–situ S isotopes analyses, were conducted on lamellar sphalerite ore, which retains the characteristics of the syn–sedimentary ore. Analysis of the trace elements revealed that the sphalerite at Mengxing are rich in Ge, Cd, As, Sb and poor in Fe, Mn, In, Sn and Co overall, suggesting a metallogenic environment of medium–low temperature. The LA–ICP–MS trace elemental mapping graph indicated that colloidal sphalerite exhibits the obvious oscillation belts. The dark zonal band of sphalerite is more enriched in Fe, Mn, Cu, Ge, As, Ag, Sb, and Pb, and depleted in Ga, Cd, and Sn, compared to the light zonal band, suggesting the various formation temperature. Based on the equation of the first principal component (PC1*) relating trace elements to mineral formation temperature, it is estimated that ore in the sedimentary stage occurred at relatively lower temperatures (174.74℃ – 203.18℃), while that of the hydrothermal stage occurred at higher temperatures (209.78℃ – 240.18℃). The S isotopic composition of sphalerite indicated a significant distinction between the sedimentary stage (δ34SVCDT = 13.29 ‰ – 37.06 ‰, with an average value of 27.97 ‰) and the hydrothermal stage (δ34SVCDT = −6.45 ‰ – 31.57 ‰, with an average of 9.01 ‰). It is hypothesized that sulfur during the early stage originated primarily from thermochemical sulfate reduction (TSR) of seawater sulfate, while sulfur during the hydrothermal stage was likely influenced by hydrothermal fluid from the deep. In conclusion, the early lamellar ores formed during the Silurian period exhibit characteristics consistent with SEDEX type mineralization, leading to initial metal pre–enrichment, followed by further enrichment of ore grade by superimposed fluid during the hydrothermal stage.

An introduction to the Bowland Shale Formation, UK: processes and resources

Abstract This volume showcases recent geological, geophysical and geochemical research on the Carboniferous Bowland Shale Formation. The Bowland Shale is a relatively thick and extensive Palaeozoic black shale unit with a long history of debate and controversy in the UK. The Bowland Shale is proven in many of the key Carboniferous basins in the Midlands, northern England and North Wales, and represents a significant, near-continuous temporal record spanning 16 Myr including the important mid-Carboniferous boundary (Mississippian–Pennsylvanian). Since the first geological surveys in the late nineteenth century, the Bowland Shale has been of interest for a variety of reasons, including the search for Irish-type Pb–Zn base metal mineral deposits, and as a source rock in conventional hydrocarbon systems. In the mid-2000s, attention turned to the Bowland Shale as a target for unconventional hydrocarbon extraction, shale gas, following success in the USA. This placed the Bowland Shale at the centre of a series of interconnected controversies and debates from the local to national scale. The geological credibility of the purported shale gas resource in the UK was – and continues to be – highly contentious. This volume contributes to a more updated view of the Bowland Shale, covering topics such as sedimentary, geochemical and physical properties and processes, basin-forming events, hydrocarbon prospectivity, mineralization and heat and fluid flow in the subsurface. The volume also includes a field guide to some of the key localities in the UK. With the benefit of hindsight offered by the latest generation of research, the early regional shale gas assessments failed to attach sufficient weight to the compositional heterogeneity, structural complexity, compartmentalization and highly variable exhumation, erosion and palaeo-heat flow history of the Bowland Shale. The following topics are identified as promising avenues for future research beyond shale gas: (1) the role of the Bowland Shale in the context of mineral systems; (2) the role of the Bowland Shale as a cap rock in the Lower Carboniferous limestone geothermal play and potentially as an analogue of CO 2 or radioactive waste storage in the UK; and (3) pathways and mechanisms for weathering, alteration and trace element release from the Bowland Shale into the surface and/or subsurface environment.

Environmental Contamination and Health Risk Assessment of Heavy Metals in the Stream Sediments of Oued Kasseb (Northerwest of Tunisia) in the Vicinity of Abandoned Pb–Zn Mine

Environmental Contamination and Health Risk Assessment of Heavy Metals in the Stream Sediments of Oued Kasseb (Northerwest of Tunisia) in the Vicinity of Abandoned Pb–Zn Mine

Cd–Pb isotopic characteristics within the Hehuashan carbonate-hosted Pb–Zn deposit, Middle-Lower Yangtze River Metallogenic Belt: Constraints for ore-forming metal sources and implications for exploration

The Hehuashan carbonate-hosted Pb–Zn deposit is a large-scale deposit situated in the Middle-Lower Yangtze-River Metallogenic Belt (MLYRMB) in China. It contains 0.99 million tons of Zn at an average grade of 1.5 % and 0.41 million tons of Pb at an average grade at 1.9 %, accompanied by critical metals of Cd and Ga. The ores are mainly composed of breccia-type and vein-type in the deposit. Though previous chemical compositions of sphalerite showed that Cd is enriched in both two types of mineralization and the sulfide sulfur isotopes research showed that the reduced sulfur is derived from the marine sulfate reduction, the source of ore-forming metals is still unclear. In this research, we studied the non-traditional stable isotope of Cd and the radioactive isotope Pb of the Hehuashan deposit to discuss the ore-forming metal sources and provide genesis constraints to the Hehuashan Pb–Zn deposit. The sphalerite Cd isotopic compositions are relatively concentrated but the Zn/Cd ratios are scattered in the Hehuashan deposit, of which the early-stage sphalerite δ114/110Cd values ranged from 0.21 ‰ to 0.30 ‰ with an outlier of 0.09 ‰, mean of 0.22 ‰ and a wide range of Zn/Cd ratios (78 to 430), and the late-stage sphalerite δ114/110Cd values ranged from 0.09 ‰ to 0.15 ‰ with two outliers of −0.05 ‰ and 0.52 ‰, mean of 0.17 ‰ with also a wide range of Zn/Cd ratios (50 to 286), both stages of Cd isotopic compositions are overlapped with the ranges of diorite and OIB & MORB, implying the Cd is might be derived from the dioritic intrusions of the Hehuashan deposit district, and the varied Zn/Cd ratios imply that the limestone also provided some of ore-forming metals to the both two ore-forming stages. Additionally, the Pb isotopic compositions of galena in the two mineralization stages exhibit a concentrated range (206Pb/204Pb = 18.2806 – 18.4190, 207Pb/204Pb = 15.6262 – 15.6484, and 208Pb/204Pb = 38.5710 – 38.6529) and all the Pb isotopic data points of the Hehuashan deposit are plotted in the right-hand side of the geochron and the overlapped field of marine sediments, Tongling dioritic intrusions, and Lower Triassic limestones in the Tongling area in the diagrams of (207Pb/204Pb)i vs. (206/204Pb)i and in the field (208Pb/204Pb)i vs. (206/204Pb)i, implying that the Pb is mainly derived from the magma of dioritic intrusions and marine sediments. Subsequently, the sulfide Cd–Pb isotopic compositions show that the ore-forming metals in the Hehuashan deposit are mainly originated from the dioritic intrusions and marine sediments. The plots of deposit genesis classification show that the Cd isotopic compositions in the Hehuashan deposit are unsuitable to the plots of δ114/110Cd vs. Zn/Cd ratios, but imply the metals were derived from multi sources. Finally, the Cd-Pb studies of the Hehaushan Pb–Zn deposit show that the earlier Lower Triassic carbonate formations and its contact with dioritic rocks should be ideal exploration targets for Pb–Zn and associated Cd sources in the Tongling mining area.

Environmental performance of unfired bricks produced from co-disposal of mine tailings and municipal solid waste incineration fly ash based on comprehensive leaching tests

The potential leaching of heavy metals is a crucial concern for construction materials produced from solidification/stabilization (S/S) treatment of wastes. This study comprehensively evaluated the leaching characteristics of heavy metals from the unfired bricks produced from co-disposal of Pb–Zn mine tailings and municipal solid waste incineration fly ash using batch, sequential, and semi-dynamic leaching tests. The results show that S/S treatment drastically reduced the leachability of heavy metals from the unfired bricks through lowering their distribution in the acid-soluble fraction. The effective diffusion coefficients of heavy metals within unfired bricks were all below 1.55 × 10−13 cm2/s, which is indicative of low mobility in the environment. The release of heavy metals from the unfired bricks was primarily governed by diffusion and dissolution. Slaking treatment of fly ash significantly reduced the leaching of heavy metals from the unfired bricks due to their improved structural integrity and compactness, which minimizes the surface area in the solid matrix accessible by the leaching medium. The leachability indices of heavy metals within the unfired bricks ranged from 13.12 to 18.10, suggesting that they are suitable for “controlled utilization” in specific scenarios. Compared to untreated mine tailings, converting them into unfired bricks could reduce the releases of heavy metals by several to hundreds of folds. These findings demonstrate that S/S can be an effective and sustainable strategy for co-disposal of mining tailings and incineration fly ash to produce construction materials with sound long-term environmental performance.

Phase equilibria in the NiO-ZnO-SiO2 and PbO-NiO-ZnO-SiO2 systems

Experimental investigation and thermodynamic modeling of the phase equilibria in the (PbO)-NiO-ZnO-SiO2 system has been undertaken to characterize Ni behavior in high-Zn slags. Phase equilibria data at 790–1700 °C were obtained through equilibration of synthetic mixtures in sealed silica ampoules or Pt-Ir / Au foils, rapid quenching, and electron probe X-ray microanalysis. Phase equilibria and liquidus isotherms of the NiO-ZnO-SiO2 system in the tridymite/cristobalite SiO2, monoxide (Ni,Zn)O, zincite (Zn,Ni)O, olivine (Ni,Zn)2SiO4 and willemite (Zn,Ni)2SiO4 phase fields were measured and the extent of the 2-liquid immiscibility gap over cristobalite was determined. Additional solid solutions: larsenite Pb(Zn,Ni)SiO4 and melilite Pb2(Zn,Ni)Si2O7 were measured in the PbO-NiO-ZnO-SiO2 system. It was found that NiO partially substitute ZnO in larsenite and melilite and may form a complete range of solubility in barysilite Pb8(Zn,Ni)Si6O21. New data were used for developing a thermodynamic database to describe the Pb/Cu-containing complex system for characterizing Ni behavior in Zn-containing slags.

The initial magma–fluid evolution of the Laochang porphyry molybdenum deposit in Lancang, Yunnan, SW China: Insights from the in-situ analysis of mica and titanite

The Laochang polymetallic deposit is the only large deposit in the Changning–Menglian Junction Zone. The deposit features by deep porphyry-skarn Mo–(Cu) and shallow vein Pb–Zn–(Ag) mineralization. Researches on the deposit have yielded extensive data, however, details about the initial evolution from magma to ore-forming fluid remain unclear. This study centers on the in-situ analysis of biotite from the porphyry, as well as phlogopite and titanite from the A vein, leading to the following insights: (1) The biotite geothermobarometer suggests the porphyry intruded in a moderate depth (2.57–4.27 km), with average parameters as P = 93 MPa, T = 697 °C, and logfO2 = -16.78. (2) The A vein in the deposit can be further subdivided into A1 K-feldspar vein and A2 quartz vein. The phlogopite in the A1 vein formed at P = 98 MPa, T = 681 °C, and logfO2 = -17.29. The pressure of the A1 vein is slightly higher than the static pressure of wall rock, attributed to pressure increment from the initial exsolved fluid. Conversely, the temperature and oxygen fugacity experience a slight decrease, due to buffering of the adjacent tuff. (3) The in-situ LA–ICP–MS U–Pb dating of the titanite in the A1 vein yields 44.4 ± 1.5 Ma (MSWD = 1.8, n = 48), comparable to the emplacement age of the porphyry (44.6–44.4 Ma). It is slightly older than the main mineralization age (43.78 Ma), further delineated the initial evolution sequence from magma to ore-forming fluid. Our research suggests that the in-situ analysis of titanite is crucial for preciously tracking the magma–fluid system, as titanite records both time and temperature information.

Major types, spatio-temporal distribution, and metallogenesis of magmatism-related polymetallic deposits in the Bangonghu–Nujiang metallogenic belt, Tibet

The Bangong–Nujiang metallogenic belt (BNMB) is one of the vital metallogenic belts in the Tibetan Plateau. At present, the metallogenic regularity on the scale of the whole metallogenic belt is still poorly understood. In this contribution, the geological, geochronological, geochemical, and isotopic data of 87 magmatism-related polymetallic deposits in the BNMB have been systematically collected to summarize the metallogenesis of polymetallic deposits in this belt. Our research shows that different segments of the BNMB have distinct metallogenic differences. The western, central, and eastern segments of the BNMB are characterized by the development of abundant Cu–Au, Fe–Cu–Cr–Ni, and W–Pb–Zn deposits, respectively. These various types of magmatism-related polymetallic deposits in the BNMB were formed between 188 Ma and 76 Ma, and the mineralization has two peak periods of 125–110 Ma and 90–75 Ma. The spatio-temporal variation of different types of magmatism-related polymetallic deposits in the BNMB is likely to be constrained by the lithospheric architecture and deep geodynamic processes. The elemental and Sr–Nd–Hf–S–Pb isotopic results indicate that various kinds of mineralization are closely related to relevant magmatism. The Cu–Au mineralization is related to dominantly mantle-derived, highly-oxidized, and less-evolved granitic intrusions; the Pb–Zn–W mineralization is genetically associated with dominantly ancient middle–upper crust-derived, relatively reduced, and highly-evolved granitic intrusions; the characteristics of the ore-causative intrusions related to Fe–Cu–Mo polymetallic mineralization are between those of the above two end members. In combination with previous studies, we propose a comprehensive model that includes four stages (>145 Ma, ∼145–125 Ma, ∼125–105 Ma, and ∼105–74 Ma) to illustrate the Jurassic–Cretaceous tectonic–magmatic–metallogenic evolution history in the whole BNMB.

Oblique distribution patterns and the underlying mechanical model of orebody groups controlled by structures at different scales

The oblique distribution of orebodies is a basic feature of the spatial distribution of orebody groups in hydrothermal deposits, and it is closely related to the shearing effect. However, the oblique distribution patterns of orebody groups controlled by ore-controlling/ore-forming structures at different scales (orebody, ore deposit and ore field scales) and the underlying formation mechanism are unclear but could be used to directly constrain mineral exploration and prospecting breakthroughs in the deep and peripheral areas of ore deposits. This paper uses the northeastern Yunnan Ge-rich Pb–Zn ore concentration area in the Sichuan–Yunnan–Guizhou metallogenic area as an example to analyse and demonstrate the oblique distribution patterns of orebodies (orebody groups) controlled by ore-forming/ore-controlling structures at different scales and the underlying mechanical model based on the Theory and Methods of Ore field Geomechanics. The results indicate that in 3D space, the oblique distributions of orebodies (veins), orebody groups and ore deposits are controlled by the mechanical properties, kinematic characteristics, and tectonic stress fields of ore-forming/ore-controlling fault structures of different sequences during the mineralization period. This study has an important guiding role for ore field-scale exploration deployment, evaluation of deep and peripheral prospecting, and exploration project arrangement, with the aim of helping mining companies increase resource reserves and production.

Compositional balance analysis: A novel method for tectono-geochemical anomaly identification and blind ore deposit prediction

Tectono-geochemical exploration always involves the study of tectono-geochemical primary halos. From the perspective of compositional data analysis, this study introduced how to use compositional balance analysis (CoBA) method to recognize tectono-geochemical anomalies and infer blind ore deposits in the deep. A case study for prediction of concealed Pb–Zn ore deposits based on tectono-geochemical data in the Huangzhuguan ore cluster, Gansu Province, China, was employed to demonstrate the potential applications of the CoBA method. First, an optimal element combination (i.e., Pb–Zn –Cd) related to near-ore halo was determined by means of CoBA method and receiver operating characteristic curve analysis. Then, according to the element zonation sequences of the primary halo in the hydrothermal deposit, the front halo element combination (i.e., As–Sb–Hg) and the tail halo element combination (i.e., W–Sn–Mo–Bi) were selected for compositional balance analysis. Finally, based on knowledge-driven CoBA method, three types of tectono-geochemical primary halos were customized to evaluate blind Pb–Zn deposits in the Huangzhuguan ore cluster. The results indicate that the CoBA method combined with the superimposed characteristics of tectono-geochemical primary haloes, proves to be effective and straightforward in interpreting Pb–Zn mineralization-related anomalies and predicting hidden Pb–Zn targets.

Evolution of skarn to quartz-vein mineralization: Insights from the Tongshanling Cu–Pb–Zn deposit, South China

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

Cenozoic Pb–Zn–Ag mineralization in the Western Alps

Abstract Metallogenic models of polyphase mountain belts critically rely on robust geochronology. We combine petrology with Rb–Sr and U–Th–Pb in situ geochronology, paired at thin-section scale, to date mineralization in deformed hydrothermal Pb–Zn–Ag deposits along an east-west transect in the Western Alps, France. The Pb–Zn–Ag veins occur in shear zones with kinematic structures consistent with the mylonitized host rocks. The ore consists mainly of galena in a quartz-phengite gangue. The paragenesis can be related to hydrothermal crystallization during periods of variable strain. Both isotope systems yield only Cenozoic ages (ca. 35 Ma and 15–20 Ma) without any pre-Alpine inheritance, clearly indicating orogenic mineralization. The metallogenic model proposed here includes significant fluid circulation along major tectonic contacts between basement and sedimentary cover during Alpine convergence.

Genesis of Pb–Zn Mineralization in the Pulang Cu Polymetallic Deposit in Yunnan Province, China: Insights from Analyses of Geology, Fluid Inclusions and C–H–O–S Isotopes

The Pulang super-large porphyry Cu polymetallic deposit, located in the Sanjiang area of Yunnan Province, is one of the largest Cu deposits in China. This deposit hosts Cu resources of ~5 × 106 t and other ore-forming elements, such as Mo, Au, Ag, Pb, Zn, Pt and Pd. Recently, obvious hydrothermal vein-type Pb–Zn mineralization, with a Pb + Zn resource of ~0.4 × 106 t, has been detected in the North Ore Section of the deposit. However, the genesis of these Pb–Zn ore bodies, especially their relationship to the major Cu ore bodies in the South Ore Section, remains controversial. We conducted geologic description, fluid inclusion petrography and microthermometry, and C, H, O and S isotope studies to uncover the genesis of Pb–Zn vein-type mineralization in North Pulang. As a result, three types of Pb–Zn veins were identified: a quartz–pyrrhotite–chalcopyrite–sphalerite–galena vein, a quartz–pyrrhotite–sphalerite–galena vein, and a calcite–quartz–pyrrhotite–galena vein. All fluid inclusions in the quartz from different veins are liquid-rich inclusions, with homogenization temperatures in the range of 184 °C–235 °C and salinities between 10.4 wt.% and 17.8 wt.% NaCl eq., indicating that the Pb–Zn ore-forming fluid was a single-phase fluid with a low temperature and low-to-medium salinity. Hydrothermal quartz in different stages displays δDwater values ranging from −46.9‰ to −120.0‰ (V-SMOW), and the calculated δ18Owater values range from 2.4‰ to 4.3‰ (V-SMOW), implying that the mineralization fluids likely originated from magma, with a minor involvement of meteoric water. The δ13CCal values (−2.3‰ to −7.9‰ V-PDB) of calcite indicate that C likely originated from a deep-seated source. The δ34S values of chalcopyrite, pyrite, pyrrhotite and sphalerite reveal that S was possibly derived from magmatic rocks. Based on the above data, it is suggested that the Pb–Zn mineralization in North Pulang was the result of the northward migration of ore-forming fluids that originated from South Pulang along the NE-trending structural fractures. A strong water–rock interaction occurred during the migration process. However, the involvement of meteoric water and accompanied cooling of fluids were most likely responsible for the precipitation of galena and sphalerite.

Magmatic-hydrothermal fluid evolution of the tin-polymetallic metallogenic systems from the Weilasituo ore district, Northeast China

The large Weilasituo Sn-polymetallic deposit is a recent exploration discovery in the southern Great Xing’an Range, northeast China. The ore cluster area shows horizontal mineralization zoning, from the inner granite body outward, consisting of high-T Sn–W–Li mineralization, middle-T Cu–Zn mineralization and peripheral low-T Pb–Zn–Ag mineralization. However, the intrinsic genetic relationship between Sn-W-Li mineralization and peripheral vein-type Pb–Zn–Ag–Cu mineralization, the formation mechanism and the deep geological background are still insufficiently understood. Here, we use fluid inclusions, trace elements concentrations in quartz and sphalerite, and H–O isotope studies to determine the genetic mechanism and establish a metallogenic model. Fluid inclusion microthermometry and Laser Raman spectroscopic analysis results demonstrates that the aqueous ore-forming fluids evolved from low-medium salinity, medium–high temperature to low salinity, low-medium temperature fluids. Laser Raman spectroscopic analysis shows that CH4 is ubiquitous in fluid inclusions of all ore stages. Early ore fluids have δ18OH2O (v–SMOW) values from + 5.5 to + 6.2‰ and δD values of approximately − 67‰, concordant with a magmatic origin. However, the late ore fluids shifted toward lower δ18OH2O (v–SMOW) (as low as 0.3‰) and δD values (~ − 136‰), suggesting mixing between external fluids derived from the wall rocks and a contribution from meteoric water. Ti-in-quartz thermometry indicates a magmatic crystallization temperature of around 700 °C at a pressure of 1.5 kbar for the magmatic ore stage. Cathodoluminescence (CL) imaging and trace element analysis of quartz from a hydrothermal vug highlight at least three growth episodes that relate to different fluid pulses; each episode begins with CL-bright, Al-Li-rich quartz, and ends with CL-dark quartz with low Al and Li contents. Quartz from Episode 1 formed from early Sn-(Zn)-rich fluids which were likely derived from the quartz porphyry. Quartz from episodes 2 and 3 formed from Zn-(Sn)-Cu-rich fluid. The early magmatic fluid is characterized by low fS2. The SO2 produced by magma degassing reacted with heated water to form SO42−, causing the shift from low fS2 to high fS2. The SO42− generated was converted to S2– by mixing with CH4-rich, Fe and Zn-bearing external fluid which led to late-stage alteration and dissolution of micas in vein walls, thus promoting crystallization of pyrrhotite, Fe-rich sphalerite and chalcopyrite and inhibiting the precipitation of anhydrite. This study shows that ore formation encompassed multiple episodes involving steadily evolved fluids, and that the addition of external fluids plays an important role in the formation of the later Cu–Zn and Ag–Pb–Zn mineralization in the Weilasituo ore district.

The genesis of the Tianbaoshan Pb[sbnd]Zn deposit in Sichuan, SW China: Insights from sphalerite and fluid inclusion compositions

The Tianbaoshan deposit, located in the Sichuan–Yunnan–Guizhou (SYG) metallogenetic belt, is one of famous PbZn deposits of Southwest China, with an established reserve of 2.6 Mt. Pb and Zn. According to the detailed field geological survey and microscopic petrography observation, three distinct ore fluid evolution stages can be divided. In this contribution, sphalerite and associated quartz from above diverse stages were carefully chosen for systematic fluid inclusion (FI) petrography, microthermometry, individual FI LA-ICP-MS analysis, Raman microspectroscopy, and in situ trace element investigation of sphalerite. The sphalerite only defines a two-phase aqueous FI type, while the FIs hosted in quartz exhibit diverse types, including two-phase aqueous FIs, vapor-rich FIs, and pure aqueous fluid inclusions. Our microthermometry results indicate that the homogenization temperature (Th) and salinity of FIs in sphalerite from the stage 1 are 109.6‐182.2 °C and 12.51–21.61 wt% NaCl equiv., respectively. The Th of the sphalerite-hosted fluid inclusions in stage 2 ranges from 97 to 158.3 °C, with a salinity range of 14.46–19.76 wt% NaCl equiv. The FIs trapped in sphalerite exhibited medium-high salinity and low Th, and Raman spectrum analysis shows that vapor composition of the FI is mainly H2O, reflecting the typical characteristics of basin brine. Measurements on quartz-hosted FIs yield homogenization temperatures from 134.3 to 233.1 °C, with a salinity from 4.49 to 12.62 wt% NaCl equiv. The gas phase composition of these inclusions is complex and consists of several components, such as CH4, N2, CO2, and H2O. The results indicate that the FIs present in quartz are dissimilar from those in sphalerite, and the sphalerite mineralization fluid has typical characteristics of basin brine and represents the ore-forming fluid. The significantly high Na and Ca of the mineralizing fluid is revealed, suggesting that the mineralizing fluid may be of the NaCa system. Combined with Ca/K, K/Na and Rb/Na ratio, typical basinal brines origin was constrained by fluid composition analysis. The gradual enrichment of Ca, Mg, and Sr in the mineralizing fluid emphasizes the positive effect of fluid-rock reactions on the precipitation of Zn. The trace element in sphalerite of the Tianbaoshan deposit is distinct from SEDEX-, skarn-, and volcanogenic massive sulfide (VMS)-type deposits and notably similar to MVT deposits. Combining with fluid inclusion and sphalerite trace elements feature, we define the Tianbaoshan deposit as a typical MVT PbZn deposit.

Chronological sequence of charcas igneous complex and their relationships with Zn–Pb–Ag mineralization events, San Luis Potosi state, Mexico

The Charcas Intrusive Complex (CIC), comprised of monzogranites and granodiorites is located at the eastern edge of the Mesa Central in México. The CIC was dated by U/Pb on zircon crystals, from Tithonian to Rupelian ages and three distinct magmatic pulses were identified: (1) Tithonian (∼150 Ma), (3) Ypresian to Lutetian (∼55–∼44 Ma), and (3) Rupelian (∼30–∼27 Ma). The Early Cretaceous to Lutetian major and trace element magma compositions, suggest that the arc monzogranites were emplaced in a growing continental crust while the Ypresian granodiorites show typical boron enrichment observed in central Mexico. The Lutetian and Rupelian granodiorites plot inside the field of cordilleran granites or continental arc magmatism where magma mixing is common and are considered as I-type granites presenting high concentration of Ba and Sr, and high Sr/Y and La/Yb ratio values. The most developed and intensely mineralized (Zn–Pb) hydrothermal event is Lutetian in age, corresponding to the peak of magma fertility conditions determined by zircon trace element chemistry and is well correlated to the skarn occurrences at around ∼47 Ma. The Ag mineralization event is related to the Rupelian dike's emplacement. Inherited zircon grains found in the magmas highlight the shallow position of the magma plumbing and the importance of the early Cretaceous magmatic intrusion in the formation of the Rupelian silver mineralization.