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Geophysical exploration techniques play a pivotal role in enhancing the accuracy of mineral prospecting predictions. However, relying solely on individual methods often introduces uncertainties. This study presents a case study from the Yongxin gold deposit, where we integrated audio-frequency magnetotelluric (AMT) methods with gravimetric surveying and high-resolution magnetic profiling to overcome this challenge. Advanced three-dimensional modeling techniques were utilized to precisely delineate lithological variations and deep-seated mineralization features inherent to the area. The inversion and interpretation of cross-sectional AMT data provided insights into the subsurface structure down to a depth of 1.5 km. This enhanced data reliability was achieved through an integrated interpretation constrained by multiple datasets, enabling a more accurate inference of the deeper geological framework. Furthermore, by amalgamating various datasets, we uncovered characteristics of deep mineralization, the three-dimensional configuration of mineralization-related rock masses, and the spatial orientation of known ore deposits. This holistic approach facilitated a comprehensive understanding of the deeper geological formations. A detailed analysis of ore-controlling structures and exploration markers led to the development of a tailored geological-geophysical model for mineral exploration within the study area, serving as a valuable reference for future deep exploration efforts. [ABSTRACT FROM AUTHOR]

The study of the fluid inclusions of W–Mo deposits in the mineralization area of Ningshan–Zhen'an , Shaanxi Province, China shows that the gas–liquid two-phase inclusions are mainly present in W–Mo deposits, and the ore-forming fluid can be divided into four types: high-temperature type, middle–high-temperature type, middle-temperature type and low-temperature type. The formation depths of the W–Mo mineralization range from 4.2 to 8.4 km. The boiling and mixing of fluid may have been important mechanisms for the formation of W–Mo mineralization. The skarn-type mineralization is dominated by magmatic water, the quartz-vein-type mineralization includes both magmatic water and meteoric water, and the meteoric water is more involved in the quartz-fluorite-vein-type, beryl-quartz-vein-type and pegmatite-type mineralization. Magma is the main source of sulfur; that is, magma is the main source of mineralization. Combined with the metallogenic setting and geological characteristics of typical ore deposits, in the process of structural system transformation in South Qinling, the ore-forming magma fluid in the Late Indosinian–Yanshanian period was uplifted and emplaced along the NW–WNW direction and NE–NNE direction, and eventually, NW–WNW fault-controlled skarn-type W–Mo mineralization and quartz-vein-type W–Mo deposits accompanied by greisenization, albitization and potash feldspathization formed. [ABSTRACT FROM AUTHOR]

By studying the light isotopic compositions of carbon, oxygen, and hydrogen, combined with previous research results on the ore-forming source of the deposit, the authors try to uncover its metallogenic origin. The δ18O and δ13C isotope signatures of dolomite samples vary between 10.2 and 13.0‰, and between −7.2 and −5.2‰, respectively, implying that the carbon derives from the upper mantle. δD and δ18O of quartz, biotite, and muscovite from different ore veins of the deposit vary between −82 and −59‰, and between 11.6 and 12.4‰, respectively, implying that the metallogenic solutions are mainly magmatic. According to the relevant research results of many isotope geologists, the fractionation degree of hydrogen isotopes increases as the depth to the Earth's core increases, and the more differentiated the hydrogen isotopes are, the lower their values will be. In other words, mantle-derived solutions can have extremely low hydrogen isotope values. This means that the δD‰ value − 134 of the pyrrhotite sample numbered SD-34 in this article may indicate mantle-derived ore-forming fluid of the deposit. The formation of the Dashuigou tellurium deposit occurred between 91.71 and 80.19 Ma. [ABSTRACT FROM AUTHOR]

In this work, we investigated in situ isotopic compositions of antimony (Sb) minerals from two substages of the ore deposits near Pezinok (Slovakia). The δ123Sb values of the primary Sb minerals range from −0.4 and +0.8‰ and increase progressively along the precipitation sequence. In the substage II, the early-formed gudmundite (FeSbS) shows in all sections the lowest δ123Sb values, followed by berthierite (FeSb2S4), stibnite (Sb2S3), and valentinite (Sb2O3) with the heaviest δ123Sb values. A similar trend was observed for the substage III, from the initially-formed stibnite, followed by kermesite (Sb2S2O), valentinite, senarmontite (both Sb2O3), and schafarzikite (FeSb2O4). The evolution can be rationalized by a Rayleigh fractionation model with a starting δ123Sb value in the fluid of +0.3‰, applying the same mineral-fluid fractionation factor to all minerals. Thus, the texturally observed order of mineralization is confirmed by diminishing trace element contents and heavier δ123Sb values in successively crystallized Sb minerals. Antimony in substage III was likely supplied from the oxidative dissolution of stibnite that formed earlier during substage II. The data interpretation, although limited by the lack of reliable mineral-fluid fractionation factors, implies that Sb precipitation within each substage occurred from an episodic metal precipitation, likely associated with a similar Sb isotope fractionation between fluid and all investigated Sb minerals. Large isotopic variations, induced by precipitation from a fluid as a response to temperature decrease, may be an obstacle in deciphering the metal source in hydrothermal ore deposits. However, Sb isotopes appear to be an excellent instrument to enhance our understanding on how hydrothermal systems operate. [ABSTRACT FROM AUTHOR]

The Zhazixi deposit hosted in sedimentary rocks is a major Sb-W deposit in South China. The mineral scheelite, which can be dated by the U-Pb method, commonly occurs in both tungsten (W)-dominated and antimony (Sb)-dominated ore veins of the deposit. Cathodoluminescence (CL) images reveal the presence of three distinct stages of scheelite (Sch-I, Sch-II and Sch-III) within the deposit. These three scheelites were dated using in-situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), yielding U-Pb ages of 158.1±5.4 Ma and 157.6 ± 4.9 Ma for Sch-I, 155 ± 11 Ma for Sch-II, and 151.3±6.1 Ma for Sch-III. These data suggest that the Zhazixi Sb-W deposit formed during the Late Jurassic (160–150 Ma) rather than the Late Triassic as previously suggested. Considering the temporal similarity with low-temperature hydrothermal Sb deposits in the Xiangzhong metallogenic province (XZMP), the formation of the Sb-W deposit may have followed a similar genetic model, where meteoric groundwater circulated to depth and extracted metals from fertile basement rocks through fluid-rock interaction, resulting in the generation of ore fluids. This study highlights that Late Jurassic low-temperature hydrothermal Sb-polymetallic mineralization in the XZMP is likely more extensive than previously perceived. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The basal unit of the Early Cambrian black shale sequence of South China hosts sulfide-rich polymetallic units, non-sulfidic vanadium-rich black shales, sapropelic alginite (combustible shale), barite, and phosphorite. This rock spectrum occurs in a paleoceanographic similar, and stratigraphically correlated, transgressive upwelling setting on the passive continental margin of the Neoproterozoic Yangtze Platform. Several centimeter-thick polymetallic sulfidic units (3–13 wt% Mo+Ni, 100–600 ppm U) have relatively light Mo (δ98/95Mo = 1.1 ± 0.2‰) and relatively heavy U isotope composition (δ238/235U = 0.2 ± 0.1‰). Several meter-thick V-rich shales with multiple ore-grade layers (0.1–0.8 wt% V, < 100 ppm U, Mo and Ni ~ 100 ppm) have isotopically lighter Mo (δ98/95Mo = 0.3 ± 0.4‰) and heavier U composition (δ238/235U = 0.4 ± 0.2‰ and up to 0.7‰). The inverse Mo versus U isotope correlation suggests that both metals were enriched by removal from anoxic to strongly euxinic bottom water in restricted basins along the rifted continental margin. Metal replenishment probably occurred via the cycling of Fe–Mn-oxyhydroxide particles across the redox boundary, with sorption/desorption of Mo (and likely Ni) in a stratified water column. In contrast, V enrichment with much lower Mo, Ni, and U contents, but more fractionated Mo and U isotope composition, reflects non-sulfidic anoxic depositional conditions in a partly open system with higher bottom water renewal rates. While Mo isotope fractionation likely occurred in the water column, U isotope fractionation may dominantly have occurred at the water-sediment interface, perhaps in a benthic organic flocculent layer. These findings indicate that local hydrodynamic control and stratified water column redox conditions may explain the observed variation of metal enrichment (Mo–Ni versus V) in the black shales. Furthermore, the high δ98/95Mo values up to 2.6‰ of the black shales studied and the correlated U and Mo isotope data suggest that Early Cambrian seawater was at least episodically broadly similar to modern seawater. [ABSTRACT FROM AUTHOR]

The relationship between Sn–Ag mineralization and mantle magmatism is a topic of high interest in current ore deposit research. Here, we investigate porphyry-, skarn-, and cassiterite-sulfide type Sn-polymetallic deposits associated with granitoids and vein-type Ag–Pb–Zn deposits hosted in sub-volcanic rocks in the southern Great Xing'an Range (SGXR), northeast China, as a case example. We use He, Ar, and S isotopes and isotopic end-member simulation calculations to determine the contribution of mantle-derived fluids/melts to the ore mineralization. Our He–Ar isotope data demonstrate that the ore-forming fluids are mixtures of shallow crust-derived fluid containing radiogenic 4He but no radiogenic 40Ar and magmatic fluids with mantle-derived 3He and 40Ar. The Pb–Zn–Ag deposits have a higher contribution of magmatic volatiles than the Sn-polymetallic deposits. Sulfide δ34S values of − 2.7 to − 0.6‰ in the Pb–Zn–Ag deposits are consistent with a magmatic sulfur source, whereas sulfides with δ34S values of − 12.2 to − 0.15‰ in the Sn-polymetallic deposits signal a possibly bimodal source of sulfur, i.e., crustal light sulfur mixed with magmatic sulfur. The noble gas compositions of the ore fluids are controlled by crustal thickness, high 3He fluxes (24 to 404 at/s/cm2), and low residence time (1 to 18 Myr) of He in the asthenosphere below the SGXR. Non-equilibrium open-system magma degassing is evidenced by the range of elevated values of 4He/40Ar* ratios (4.8–127). The 3He/heat ratio of the ore fluids from the Sn and Pb–Zn–Ag deposits overlap (0.01–0.76 × 10−2 cm3 STP J−1 (cubic centimeter at standard temperature and pressure per joule) and 0.02–1.08 × 10−2 cm3 STP J−1, respectively), indicating a consequence of conduction of mantle-derived heat across the magma-hydrothermal interface. Furthermore, an increasing abundance of Sn reserves in the SGXR deposits can be equated with an increase in the mantle-derived He component in the ore fluids. These findings suggest that a continuous flux of mantle-derived fluids/melts plays an essential role in Sn–Ag–Pb–Zn mineralization. [ABSTRACT FROM AUTHOR]

We use Sr-Nd isotopes of apatite and trace element compositions of apatite-zircon pairs from a major ore layer in each of three selected magmatic Fe-Ti-V oxide ore deposits (Hongge, Panzhihua, and Taihe) in the Emeishan large igneous province (LIP) in southwestern China to contrast the magmatic controls on ore formation. The average contents of REEs in apatite from a representative ore zone/layer in each of these deposits are higher than the predicted values of apatite crystallizing from a melt with REE contents assumed to be the same as the average values of high-Ti basalts in the Emeishan LIP, confirming that the ore-forming magmas all experienced higher degrees of fractional crystallization by major silicate minerals than the average basalt. The apatites Sm/Yb and Sr/Y indicate that the Panzhihua magma was generated at a shallower depth and experienced higher degree of plagioclase fractional crystallization than Taihe and Hongge. The apatite Sr-Nd isotopes can be reproduced by ~ 8 wt% contamination with Precambrian gneiss-schist in the parental magma for Hongge and by ~ 10 wt% and ~ 25 wt% contamination with marbles in the parental magmas for Panzhihua and Taihe, respectively. A recycled, high-T altered oceanic gabbroic component in the mantle source is a viable alternative to the marble contamination model for Taihe. Coexisting zircon trace element compositions reveal that the parental magma for Taihe (ΔFMQ+4.0) is more oxidized than those for Hongge (ΔFMQ−0.4) and Panzhihua (ΔFMQ−0.7), questioning that magma oxidation played a critical role in the genesis of Fe-Ti-V oxide ore deposits in the Emeishan LIP. [ABSTRACT FROM AUTHOR]

The Gejiu ore district (~ 3.2 Mt Sn) is located in eastern Yunnan Province, southwest China, and is one of the largest Sn polymetallic ore districts in the world. Athough it has been widely studied, the petrogenesis of ore-related granites is still unclear. In this paper, we present petrological, geochemical, and geochronological data on the granites associated with the Kafang Cu–Sn deposit in the Gejiu ore district (65 Mt Cu ore at a grade of 1.2% and 32 Mt Sn ore at a grade of 0.6%). We use these data to constrain the source, evolution, oxygen fugacity, and tectonic setting of the granitic magmatism. Zircon U–Pb dating yielded an age of 82.8 ± 0.6 Ma for the Kafang granite. The high zircon δ18O values (7.45–9.74‰; mean = 8.80‰) and narrow range of εNd(t) values (–9.0 to –7.7) of the Kafang granite indicate a highly evolved S-type granite derived by partial melting of metamorphic basement rocks of the Jiangnan orogenic belt. Rayleigh fractional crystallization modeling, along with the increase in Hf and Sn contents and decrease in Eu/Eu* values of zircons, record extensive fractional crystallization, and Sn enrichment during magmatic evolution. The Kafang granite was relatively reduced, as evidenced by low zircon Ce/Ce* (10.0–366; mean = 171), (Ce/Nd)N (0.76–8.32; mean = 4.41), △FMQ (–2.5 to 1.2) values, and Fe3+-depleted biotite compositions (Fe3+/(Fe3+ + Fe2+) = 0–0.10), which were favorable for Sn mineralization but not for Cu mineralization. Copper in the Kafang deposit may not have been derived from the granite. Our results suggest that biotite and zircon geochemical compositions, particularly biotite Mg# and A/CNK values and zircon Hf contents, Eu anomalies, and Ce/Ce* and (Ce/Nd)N ratios, are robust tracers of different types of magmatic-hydrothermal ore deposits (i.e., Cu, Mo, W, and Sn). Late Cretaceous magmatism in the Gejiu region and other areas along the southern margin of South China formed an E–W-trending igneous belt that was likely related to northward subduction of the Neo-Tethyan plate rather than northwestward subduction of the Paleo-Pacific plate. [ABSTRACT FROM AUTHOR]

The genesis (primary versus secondary) of Mn carbonate-rich sediments, which consist of sub-economic rocks and ore deposits, remains hotly debated. Here, we investigated the petrographic, geochemical, and C–Mo isotopic characteristics of the Zhaosu Mn carbonate deposit in northwestern China, in order to provide constraints on its origin. The Mn ores occur within a Carboniferous marine transgressive siliciclastic-carbonate succession, and are mainly comprised of Mn carbonate minerals with subordinate alabandite. Within the Mn ores, organic matter is commonly replaced by Mn carbonates, coupled with concentric Mn carbonates, suggesting that Mn carbonates formed during diagenesis. This is further supported by their negative δ13CVPDB values (from −2.4 to −10.7‰), negative δ98MoNIST+0.25 values (from −0.1 to −3.7‰), shale-normalized positive Ce anomalies (up to 1.2), and lower Y/Ho ratios (29-35) relative to seawater (~44). These all indicate that the Zhaosu Mn carbonate ores formed due to original Mn oxide reduction coupled with organic matter degradation during diagenesis. The extremely negative Mo isotopic values (as low as −3.7‰) likely resulted from a dual effect of original Mn oxide adsorption and subsequent Mo sequestration within weakly sulfidic pore waters during diagenesis. The ubiquity of alabandite in the Mn ores indicates a significant separation between Mn and Fe, and combined with the country-rock limestones with negative Ce anomalies, we infer that an oxic-suboxic stratified water column might have characterized the Zhaosu basin during Mn deposition. By compiling geochemical and isotopic features of major Mn carbonate-rich sediments in Earth's history, we argue that ancient Mn carbonate-rich sediments, especially economic ore deposits, might result from original Mn oxide reduction during diagenesis and thus are a reliable proxy for oxic oceanic conditions. [ABSTRACT FROM AUTHOR]

Continuous resource supply is one of the key points to improve comprehensive national strength. Resource prediction models supportive of target delineation for successful discovery of mineral deposits are consequently pursued and explored by academic communities. Boosting as a classic ensemble learning technique, which can partly improve classification and/or prediction accuracy, has been greatly developed nowadays. To test the efficiency of boosting algorithms in mineral prospectivity prediction, three boosting methods were compared in this research. The Hongyuntan–Chilongfeng mining district chosen as the study area hosts a number of marine volcanic–sedimentary Fe deposits, skarn Fe deposits, Cu–Ni sulfide deposits, etc. Ore-bearing strata, buffers of faults and igneous intrusions, and geochemical distributions of mineralization related elements were used as predictors in this study. To overcome the weakness of the traditional AdaBoost algorithm, this research proposes an improved AdaBoost algorithm. By optimizing the weighting parameters, the weights put on the "difficult-to-learn" samples can be adjusted. In addition, using the Real AdaBoost algorithm to give real number weights to weak classifiers within the range of [0, 1] makes them work evenly during the classification, which better corresponds to the idea of data integration. The results of the experiments showed that the improved AdaBoost and the Real AdaBoost algorithms enhanced the accuracy of classification significantly and performed much better than the traditional algorithm in recognition and extraction of metallogenic anomalies in this area. It is assumed that the user-friendliness and effectiveness of boosting models make them potential data-driven alternatives for regional-scale mineral prospectivity prediction in other mining districts. [ABSTRACT FROM AUTHOR]

The ore deposits of the Mesozoic age in South China can be divided into three groups, each with different metal associations and spatial distributions and each related to major magmatic events. The first event occurred in the Late Triassic (230-210 Ma), the second in the Mid-Late Jurassic (170-150 Ma), and the third in the Early-Mid Cretaceous (120-80 Ma). The Late Triassic magmatic event and associated mineralization is characterized by peraluminous granite-related W-Sn-Nb-Ta mineral deposits. The Triassic ore deposits are considerably disturbed or overprinted by the later Jurassic and Cretaceous tectono-thermal episodes. The Mid-Late Jurassic magmatic and mineralization events consist of 170-160 Ma porphyry-skarn Cu and Pb-Zn-Ag vein deposits associated with I-type granites and 160-150 Ma metaluminous granite-related polymetallic W-Sn deposits. The Late Jurassic metaluminous granite-related W-Sn deposits occur in a NE-trending cluster in the interior of South China, such as in the Nanling area. In the Early-Mid Cretaceous, from about 120 to 80 Ma, but peaking at 100-90 Ma, subvolcanic-related Fe deposits developed and I-type calc-alkaline granitic intrusions formed porphyry Cu-Mo and porphyry-epithermal Cu-Au-Ag mineral systems, whereas S-type peraluminous and/or metaluminous granitic intrusions formed polymetallic Sn deposits. These Cretaceous mineral deposits cluster in distinct areas and are controlled by pull-apart basins along the South China continental margin. Based on mineral assemblage, age, and space-time distribution of these mineral systems, integrated with regional geological data and field observations, we suggest that the three magmatic-mineralization episodes are the result of distinct geodynamic regimes. The Triassic peraluminous granites and associated W-Sn-Nb-Ta mineralization formed during post-collisional processes involving the South China Block, the North China Craton, and the Indo-China Block, mostly along the Dabie-Sulu and Songma sutures. Jurassic events were initially related to the shallow oblique subduction of the Izanagi plate beneath the Eurasian continent at about 175 Ma, but I-type granitoids with porphyry Cu and vein-type Pb-Zn-Ag deposits only began to form as a result of the breakup of the subducted plate at 170-160 Ma, along the NNE-trending Qinzhou-Hangzhou belt (also referred to as Qin-Hang or Shi-Hang belt), which is the Neoproterozoic suture that amalgamates the Yangtze Craton and Cathaysia Block. A large subduction slab window is assumed to have formed in the Nanling and adjacent areas in the interior of South China, triggering the uprise of asthenospheric mantle into the upper crust and leading to the emplacement of metaluminous granitic magma and associated polymetallic W-Sn mineralization. A relatively tectonically quiet period followed between 150 and 135 Ma in South China. From 135 Ma onward, the angle of convergence of the Izanagi plate changed from oblique to parallel to the coastline, resulting in continental extensional tectonics and reactivation of regional-scale NE-trending faults, such as the Tan-Lu fault. This widespread extension also promoted the development of NE-trending pull-apart basins and metamorphic core complexes, accompanied by volcanism and the formation of epithermal Cu-Au deposits, granite-related polymetallic Sn-(W) deposits and hydrothermal U deposits between 120 and 80 Ma (with a peak activity at 100-90 Ma). [ABSTRACT FROM AUTHOR]

The Huangshaping deposit is unique in southern Hunan Province, China, as it hosts economic reserves of both W–Mo and Pb–Zn mineralization, which are usually associated with granite and granodiorite porphyry in this area, respectively. This study reports results of in situ LA-MC-ICP-MS sulphur isotopic composition analyses conducted on sulphides from both W–Mo and Pb–Zn mineralization from the Huangshaping deposit with the aim of constraining ore genesis for this deposit. All samples from the proximal W–Mo mineralization have relatively uniform and high δ34S values (8.7 ‰ to 16.0 ‰), close to the range for carbonate sediments in this deposit (13.8 ‰ to 18.1 ‰). These patterns suggest that the granite porphyry in this deposit was the sulphur source for W–Mo mineralization, and that the assimilation of evaporite from the carbonate sediments led to the high δ34S values of the granite porphyry. Sulphides from the Pb–Zn mineralization have δ34S values (2.2 ‰ to 10.3 ‰) lower than those of the W–Mo mineralization, and generally increase in this paragenetic order, with the lowest δ34S values being similar to those of the basement (3.8 ‰ to 7.7 ‰). These patterns indicate that the original sulphur for the Pb–Zn mineralization was most likely derived from the basement, with input of sulphur from the carbonate sediments increasing during the evolution of ore-forming fluids. On the basis of the measured sulphur isotopic compositions, it is suggested that the ore-forming materials for the W–Mo mineralization were derived from the granite porphyry, whereas ore-forming materials extracted from the basement dominated the Pb–Zn mineralization. [ABSTRACT FROM AUTHOR]

The West Qingling Orogen is endowed with more than 1100t gold resources and with 50 gold deposits, ranking it the third-largest gold province in China. The Jianchaling giant gold deposit with 52 t gold reserve is a typical orogenic gold deposit in West Qinling Orogen. The deposit lacks accurate and direct metallogenic age. Five pyrite samples collected from the quartz-polymetallic veins yielded Re–Os isochron age of 206.3 ± 2.7 Ma and an initial 187Os/188Os ratio of 0.1154 ± 0.0016 (MSWD = 0.54). The pyrites were analyzed by the electron microprobe (EMPA), and the results show that the iron content ranges from 45.1 to 47.8 wt.%, the sulfur content ranges from 52.0 to 53.5 wt.%, and the gold content varies from 0.022 to 0.035%. The higher gold content means that gold is closely related to pyrite, which is a gold-bearing mineral. Moreover, the age is very close to the previous fuchsite 40Ar/39Ar isotopic ages of 199–194 Ma, which indicates that the gold mineralization at Jianchaling has begun in the Late Triassic (206 Ma), and continued into the Early Jurassic. Through summary and comparison, it is found that the gold metallogenic age of the southern ore belt of the Mian-Lue Suture belt in the West Qinling is younger than that of the northern ore belt, suggesting that the gold deposits in the southern ore belt such as Jianchaling were formed in the transitional period from oceanic subduction to continental collision. [ABSTRACT FROM AUTHOR]

South China can be divided into four metallogenic belts: The Middle-Lower Yangtze Metallogenic Belt (MLYB), Qinzhou-Hangzhou Metallogenic Belt (QHMB), Nanling Metallogenic Belt (NLMB), and Wuyi Metallogenic Belt (WYMB). The major mineralization in the four metallogenic belts is granite-related Cu–Au–Mo and porphyrite Fe-apatite, porphyry Cu (Au), and epithermal Pb–Zn–Ag, hydrothermal Cu–Au–Pb–Zn–Ag, and granite-related skarn-type and quartz-veins W–Sn, respectively. Low-temperature thermochronology, including fission-track and U-Th/He dating, has been widely used to constrain tectonic thermal evolution and ore deposits preservation. Understanding fission-track annealing and He diffusion kinetics in accessory minerals, such as zircon and apatite, is essential for dating and applications. In this study, previous zircon fission-track (ZFT) and apatite fission-track (AFT) ages in South China were collected. The result shows that the ZFT ages are mainly concentrated at 140–90 Ma, and the AFT ages are mainly distributed at 70–40 Ma. The age distribution and inversion temperature–time paths reveal heterogeneous exhumation histories in South China. The MLYB experienced Late Cretaceous-Cenozoic extremely slow exhumation after rapid cooling in the Early Cretaceous. The northern QHMB (i.e. from southern Anhui province to the Hangzhou Bay) had a relatively faster rate of uplifting and denudation than the southern QHMB in the Cretaceous. Subsequently, the northern QHMB rapidly exhumed, while the continuously slow exhumation operated the southern QHMB in the Cenozoic. The southern NLMB had a more rapid cooling rate than the northern NLMB during the Cretaceous time, and the whole NLMB experienced rapid cooling in the Cenozoic, except that the southern Hunan province had the most rapid cooling rate. The WYMB possibly had experienced slow exhumation since the Late Cretaceous. The exhumation thickness of the four metallogenic belts since 90 Ma is approximately calculated as follows: the MLYB ≤ 3.5 km, the northern QHMB concentrated at 3.5–5.5 km, and the southern QHMB usually less than 3.5 km, the NLMB 4.5–6.5 km and the WYMB < 3.5 km. The exhumation thickness of the NLMB is corresponding to the occurrence of the world-class W deposits, which were emplaced into a deeper depth of 1.5–8 km. As such, we infer that the uplifting and denudation processes of the four metallogenic belts have also played an important role in dominated ore deposits. [ABSTRACT FROM AUTHOR]

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

The Xiaokele Cu (–Mo) deposit is a recently discovered porphyry deposit in the northern Great Xing'an Range (GXR) of northeast China. The ore bodies in this deposit are mainly hosted within granodiorite porphyry intrusions. Potassic, phyllic, and propylitic alteration zones develop from center to edge. In this paper, we present zircon LA–ICP–MS U–Pb ages, zircon Hf isotopic compositions, and whole-rock geochemistry of the ore-bearing granodiorite porphyries from the Xiaokele Cu (–Mo) deposit. Zircon U–Pb dating suggests that the Xiaokele granodiorite porphyries were emplaced at 148.8 ± 1.1 Ma (weighted-mean age; n = 14). The Xiaokele granodiorite porphyries display high SiO2, Al2O3, Sr, and Sr/Y, low K2O/Na2O, MgO, Yb, and Y, belonging to high-SiO2 adakites produced by partial melting of the subducted oceanic slab. Marine sediments were involved in the magma source of the Xiaokele granodiorite porphyries, as indicated by enriched Sr–Nd isotopic compositions (εNd(t) = − 1.17– − 0.27), low positive zircon εHf(t) values (0.4–2.2), and high Th contents (4.06–5.20). The adakitic magma subsequently interacted with the mantle peridotites during ascent through the mantle wedge. The Xiaokele granodiorite porphyries were derived from slab melting during the southward subduction of the Mongol–Okhotsk Ocean. [ABSTRACT FROM AUTHOR]

The mechanics of crustal growth in the Altaids during the Phanerozoic is still not well understood. This paper reports new geochronological, geochemical, and isotopic data from Paleozoic adakitic intrusions in the Dananhu arc in the Chinese Eastern Tianshan with the aim of better understanding the specific mechanisms of crustal growth. Our new LA-ICPMS U–Pb zircon age data show that four phases of adakitic intrusions formed at 410–413 Ma, 385–387 Ma, 335 Ma, and 313–311 Ma. Combined with previous data of ours and from the literature, there were seven phases of adakitic intrusions from the Silurian to early Permian. All these adakitic intrusions have distinctive geochemical-isotopic signatures with high Na and Al, high Sr, low Yb and Y, high Sr/Y and (La/Yb)N values, relatively high MgO contents and Mg numbers (Mg# = 41–70), high abundances of compatible elements (Cr = 1.66–46.30 ppm, Ni = 2.40–26.96 ppm), and positive high εHf (t) (+ 7.1 to + 15.6) and a TDM (Ma) range from 325 to 670 Ma. These adakitic intrusions were associated with essential Cu polymetallic mineralization in the Dananhu arc. The above chemical data and relations indicate that the processes of oceanic slab melting generated these adakitic rocks. Our new geochronological, geochemical and isotopic data, integrated with the geology of the Dananhu intra-oceanic arc, lead us to conclude that multiphase of hot/young oceanic crust subduction and melting generated the massive crustal growth in the Silurian–early Permian. Our results indicate that the magmas were derived by slab melting of hot/young oceanic crust, which was one of the most critical mechanisms of continental crustal growth in the Paleozoic accretionary orogen of the Altaids. [ABSTRACT FROM AUTHOR]

The Yangla Cu deposit is the largest ore deposit in the Jinshajiang polymetallic metallogenic belt, northwest Yunnan, China. There is no consensus on the genesis of the ore deposit owing to the limited studies on the chemical compositions of sulfides. This study used an electron probe micro-analyzer to constrain the chemical compositions of pyrite, chalcopyrite, molybdenite, and sphalerite in the porphyry Cu ore of the Yangla Cu deposit and compared them with the chemical compositions of sulfides in the skarn Cu ore. The trace element contents and their occurrences were used to estimate the metallogenic temperature and infer the genesis of the Yangla deposit. The results show that the sulfides in the porphyry Cu ores have variations of ore element concentrations relative to their theoretical values. Pyrite is depleted in S but elevated in Fe; chalcopyrite is depleted in Cu, Fe, and S; and molybdenite and sphalerite are enriched in S whilst depleted in Mo and Zn. The concentrations of the main metallogenic elements Cu, Fe, Mo, Zn, and S in the porphyry are generally lower than those in skarn, suggesting that the porphyry ore was formed in a moderate to moderate-high temperature metallogenic environment. The formation time may also be slightly later than that of the skarn Cu ore. Elements such as As, Co, Cu, Pb, Zn, Mo, Cd, and Ni mainly exist as isomorphic replacements and mineral inclusions in the sulfides of both porphyry and skarn Cu ores. The trace element features of sulfides in the two ore bodies show that the Yangla Cu deposit may be a composite super imposed ore deposit, and its formation has undergone the process of exhalative-sedimentary to skarn-porphyry mineralization. [ABSTRACT FROM AUTHOR]

Understanding the relationship between mineral occurrences and host granitic rocks can be controversial. The Zaozigou Au-Sb deposit (118 t Au, 0.12 Mt Sb), hosted in metasedimentary rocks and dacitic to granodioritic sills and dikes, is one such example of a large gold deposit argued to have formed from either magmatic or metamorphic hydrothermal processes. Two populations of monazite are identified within a mineralized dacite located along a major shear zone. Magmatic monazite commonly occurs within magmatic biotite and quartz phenocrysts and is characterized by uniform and high Th concentrations. It has a crystallization age of 238.3 ± 2.6 Ma, consistent with the zircon U-Pb age of 238.0 ± 1.8 Ma from the same dacite. Hydrothermal monazite is associated with sulfides and sericite, and has a 207Pb-corrected 206Pb/238U age of 211.1 ± 3.0 Ma. The amount of Th in hydrothermal monazite is widely variable. The low Th content of some monazite grains reflects direct precipitation from a metamorphic hydrothermal fluid. Furthermore, the elevated Th content in other hydrothermal monazite grains is likely due to the release of Th (and U) into hydrothermal fluids by dissolution of pre-existing Th-rich minerals in the country rock during ore-related alteration events. The magmatism, which overlaps Middle-Late Triassic terrane subduction-accretion in the West Qinling orogen, thus pre-dates the ore-forming event by about 30 m.y. The δ34S values of pyrite, arsenopyrite, stibnite, marcasite, and chalcopyrite from disseminated- and vein-type ores range from − 12.0 to − 5.5‰. Such negative values are distinct from those measured for other deposits in the northwestern part of the orogen that are genetically related to Triassic magmatism, including the Xiekeng-Jiangligou-Shuangpengxi Cu-Au-Fe-Mo skarn, Laodou reduced intrusion-related Au, and Gangcha epithermal Au ores. The Zaozigou deposit is best classified as an epizonal orogenic Au-Sb deposit. Our results demonstrate the usefulness of high-precision in situ geochronology on monazite for deciphering age relationships in ore deposits that have spatial associations with granitic rocks, thus aiding in the testing of the veracity of ore formation models. [ABSTRACT FROM AUTHOR]

The Muli antimony deposit is located in the Au–Sb polymetallic metallogenic belt in south-eastern Yunnan, China. In this paper, we investigated the concentrations of trace elements in gangue minerals, mainly calcite, quartz, and pyrite, which were formed at different metallogenic stages. Meanwhile, the host rocks, predominantly composed of limestone, are also analysed for comparison. The calcite from the Nadan ore section is enriched with medium-heavy rare earth elements (M-HREEs), likely due to the presence of a high concentration of Fe and Mn impurities, which results in the preferential enrichment of M-HREEs in the calcite. Alternatively, the calcite may be precipitated from the M-HREE-rich granitic leaching fluid. In the Muli ore section, both quartz and pyrite in the metallogenic period show enrichment with light rare earth elements (LREEs), and the wall rock is also enriched with LREEs, which indicates that the wall rock material was involved in the metallogenic process. The W-shaped tetrad effect of quartz in the late metallogenic stage was interpreted to determine extensive fluid–rock interactions in highly fractionated Si-rich systems. Fe and Mn impurities cause M-HREE to be preferentially enriched with calcite to some extent. Whether mineralization is related to granite deserves further study. Eu and Ce anomalies of different types of gangue minerals indicate that the temperature and the fO2 were constantly changing during mineralization, and the temperature of the main ore-stage was higher than 200 °C in an oxidized state. The various REE patterns, LREE/HREE and (La/Yb)N values, reveal that there may be multi-sources and multi-stage hydrothermal activities in the Muli antimony deposit. The REE distribution patterns of minerals are likely interfered with by many internal and external factors. Studies on REE characteristics of calcite, quartz, pyrite and limestone in the Muli antimony deposit have greatly improved the understanding of ore-forming fluids. When we traced the origin and evolution of ore-forming fluids by means of mineral REE distribution patterns, in addition to the determination of inclusions of ore minerals related to mineralization and the in situ analysis methods performed by LA-ICP-MS, we should also combine the REE characteristics of various minerals or trace the ore-forming fluids with multiple methods. [ABSTRACT FROM AUTHOR]

The Sichuan–Yunnan–Guizhou (SYG) metallogenic province of southwest China is one of the most important Zn–Pb ore zones in China, with ~ 200 Mt Zn–Pb ores at mean grades of 10 wt.% Zn and 5 wt.% Pb. The source and mechanism of the regional Zn–Pb mineralization remain controversial despite many investigations that have been conducted. The Wusihe Zn–Pb deposit is a representative large-scale Zn–Pb deposit in the northern SYG, which mainly occurs in the Dengying Formation and yields Zn–Pb resources of ~ 3.7 Mt. In this paper, Zn and S isotopes, and Fe and Cd contents of sphalerite from the Wusihe deposit were investigated in an attempt to constrain the controls on Zn and S isotopic variations, the potential sources of ore-forming components, and the possible mineralization mechanisms. Both the δ66Zn and δ34S values in sphalerite from the Wusihe deposit increase systematically from the bottom to the top of the strata-bound orebodies. Such spatial evolution in δ66Zn and δ34S values of sphalerite can be attributed to isotopic Rayleigh fractionation during sphalerite precipitation with temperature variations. The strong correlations between the Zn–S isotopic compositions and Fe–Cd concentrations in sphalerite suggest that their variations were dominated by a similar mechanism. However, the Rayleigh fractionation mechanism cannot explain the spatial variations of Fe and Cd concentrations of sphalerite in this deposit. It is noted that the bottom and top sphalerites from the strata-bound orebodies document contrasting Zn and S isotopic compositions which correspond to the Zn and S isotopic characteristics of basement rocks and host rocks, respectively. Therefore, the mixing of two-source fluids with distinct Zn–S isotopic signatures was responsible for the spatial variations of Zn–S isotopic compositions of sphalerite from the Wusihe deposit. The fluids from basement rocks are characterized by relatively lighter Zn (~ 0.2 ‰) and S (~ 5 ‰) isotopic compositions while the fluids from host rocks are marked by relatively heavier Zn (~ 0.6 ‰) and S (~ 15 ‰) isotopic compositions. [ABSTRACT FROM AUTHOR]

A well reasoned lead (Pb) isotope-driven provenance study lies in concert with a comprehensively evaluated database of geological ore sources and accompanying archaeological and contextual information. In this paper we have compiled and evaluated all currently available Pb isotope data for galena and K-feldspars in China, and provided geological interpretations for how their ore-forming substances evolved across relevant tectonic terrains. We pay particular attention to the geological settings of host ore deposits that were likely exploited in ancient and historic China, detailing the heterogeneity and homogeneity of their ore formation across different metallogenic provinces and belts. Using the isotope database, and supportive geological and archaeological background information, three case studies are presented that detail the provenancing of Chinese cultural materials. The isotope data themselves are presented in ternary diagrams that allow for their concise and accurate comparison. [ABSTRACT FROM AUTHOR]

A type of carbonate-hosted lead-zinc (Pb-Zn) ore deposits, known as Mississippi Valley Type (MVT) deposits, constitutes an important category of lead-zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping with or without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H2S, rather than HS− or S2−, dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb-Zn deposits. [ABSTRACT FROM AUTHOR]

The Dalingshang W-Cu deposit is located in the North section of the Dahutang ore field, northern Jiangxi Province, South China. Vein- and breccia-style tungsten-copper mineralization is genetically associated with Mesozoic S-type granitic rocks. Infrared and conventional microthermometric studies of both gangue and ore minerals show that the homogenization temperatures for primary fluid inclusions in wolframite (~ 340 °C) are similar to those in scheelite (~ 330 °C), but about 40 °C higher than those of apatite (~ 300 °C) and generally 70 °C higher than those in coexisting quartz (~ 270 °C). Laser Raman analysis identifies CH4 and N2 without CO2 in fluid inclusions in scheelite and coexisting quartz, while fluid inclusions in quartz of the sulfide stage have variable CO2 content. The ore-forming fluids overall are characterized by high- to medium-temperature, low-salinity, CH4, N2, and/or CO2-bearing aqueous fluids. Chalcopyrite, muscovite, and sphalerite are the most abundant solids recognized in fluid inclusions from different ores. The H-O-S-Pb isotope compositions favor a dominantly magmatic origin for ores and fluids, while some depleted δ34S values (− 14.4 to − 0.9‰) of sulfides from the sulfide stage are most likely produced by an increase of oxygen fugacity, possibly caused by inflow of oxidized meteoric waters. The microthermometric data also indicate that a simple cooling process formed early scheelite and wolframite. However, increasing involvement of meteoric waters and fluid mixing may trigger a successive deposition of base metal sulfides. Fluid-rock interaction was critical for scheelite mineralization as indicated by in-situ LA-ICP-MS analysis of trace elements in scheelite. [ABSTRACT FROM AUTHOR]

The Au-Ag-Pb-Zn-Cu epithermal deposit Banská Hodruša of intermediate-sulphidation type is located in the Middle Miocene Štiavnica stratovolcano on the inner side of the Carpathian arc in Slovakia. This deposit represents an unusual subhorizontal multi-stage vein system, related to processes of underground cauldron subsidence and exhumation of a subvolcanic granodiorite pluton. Veins are developed on a low-angle normal shear zone, possibly representing a detachment zone in andesitic wall rocks that formed during emplacement and exhumation of the granodiorite pluton. The deposit consists of two parts, separated by a thick sill of quartz-diorite porphyry. The eastern part is currently mined, and the western part has already been depleted. The Banská Hodruša mineralization was formed during four stages: (1) low-grade silicified breccia at subhorizontal structures at the base of the deposit; (2) stockwork of steep veins with rhodonite-rhodochrosite, quartz-sulphide-carbonate and quartz-gold assemblages; (3) thin quartz-gold veins with medium dip in tension cracks inside the shear zone and complementary detachment hosted quartz-base metals-gold veins; (4) Post-ore veins. Gold and electrum (920-730) occur as intergrowths with base metal sulphides or hosted in quartz and carbonates, accompanied by Au-Ag tellurides (hessite, petzite). Rare Te-polybasite and Cu-cervelleite result from re-equilibration of early Te-bearing minerals during cooling. Sulphide minerals include low Fe sphalerite (~ 1.25 wt%), galena, chalcopyrite, and pyrite. The wall rock alteration is represented mostly by adularia, illite, chlorite, quartz, calcite and pyrite. Precipitation of gold, Au-Ag tellurides, Mn-bearing minerals and adularia resulted from boiling of fluids due to hydraulic fracturing, as well as opening of dilatational structures within the shear zone. [ABSTRACT FROM AUTHOR]

The Weibao copper-lead-zinc skarn deposit is located in the northern East Kunlun terrane, NW China. Igneous intrusions in this deposit consist of barren diorite porphyry (U-Pb zircon age of 232.0 ± 2.0 Ma) and ore-bearing quartz diorite and pyroxene diorite (U-Pb zircon ages of 223.3 ± 1.5 and 224.6 ± 2.9 Ma, respectively). Whole-rock major and trace element and accessory mineral (zircon and apatite) composition from these intrusions are studied to examine the different geochemical characteristics of ore-bearing and barren intrusions. Compared to the barren diorite porphyry, the ore-bearing intrusions have higher Ce4+/Ce3+ ratios of zircon and lower Mn contents of apatite, indicating higher oxidation state. Besides, apatite from the ore-bearing intrusions shows higher Cl contents and lower F/Cl ratios. These characteristics collectively suggest the higher productivity of ore-bearing quartz diorite and pyroxene diorite. When compared with ore-bearing intrusions from global porphyry Cu deposits, those from Cu-Pb-Zn skarn deposits display lower Ce4+/Ce3+ and EuN/EuN* ratios of zircon and lower Cl and higher F/Cl ratios of apatite. We conclude that these differences reflect a general geochemical feature, and that zircon and apatite composition is a sensitive tool to infer economic potential of magmas and the resulting mineralization types in intrusion-related exploration targets. [ABSTRACT FROM AUTHOR]

The Dashuigou tellurium (Te) deposit in Shimian city, Sichuan Province is the only known independent Te ore deposit in China. Samples were collected by 1/50,000 stream sediment survey and analyzed by inductively coupled plasma-mass spectrometry, X-ray fluorescence spectrometry, emission spectrometry, and atomic absorption spectroscopy. An ore prospecting model for the Dashuigou Te deposit was then established. In the Dashuigou area, bismuth (Bi), Te, and gold (Au) concentrations in stream sediment samples displayed weak-positive anomalies, while silver (Ag) displayed a weak-negative anomaly. Bi, Te, Ag, and Au anomalies are regarded as indicators of Te deposits; the greater the ratio of Te + Bi/Au + Ag, the larger the possibility of an independent tellurobismuthite deposit. The ratio calculated from our samples is 7.288. Five locations were identified for prospecting for Te minerals by this model, including the northern part of the Dashuigou Te deposit, Majiagou, Tizigou, southeastern Miaoping, and northern Baishuihe. These five regions are within the Dashuigou dome anticline, the exposed strata of which are controlled by tracing the tensile shear fracture; the metallogenic geological conditions and geochemical characteristics are the same as those of the known Dashuigou Te deposit. Already, Te-Bi veins have been found in some of these areas. [ABSTRACT FROM AUTHOR]

The Nanyangtian skarn-type scheelite deposit is an important part of the Laojunshan W-Sn polymetallic metallogenic region in southeastern Yunnan Province, China. The deposit comprises multiple scheelite ore bodies; multilayer skarn-type scheelite ore bodies are dominant, with a small amount of quartz vein-type ore bodies. Skarn minerals include diopside, hedenbergite, grossular, and epidote. Three mineralization stages exist: skarn, quartz-scheelite, and calcite. The homogenization temperatures of fluid inclusions in hydrothermal minerals that formed in different paragenetic phases were measured as follows: 221-423 °C (early skarn stage), 177-260 °C (quartz-scheelite stage), and 173-227 °C (late calcite stage). The measured salinity of fluid inclusions ranged from 0.18% to 16.34% NaCleqv (skarn stage), 0.35%-7.17% NaCleqv (quartz-scheelite stage), and 0.35%-2.24% NaCleqv (late calcite vein stage). Laser Raman spectroscopic studies on fluid inclusions in the three stages showed H2O as the main component, with N2 present in minor amounts. Minor amounts of CH4 were found in the quartz-scheelite stage. It was observed that the homogenization temperature gradually reduced from the early to the late mineralization stages; moreover, δ13CPDB values for ore-bearing skarn in the mineralization period ranged from − 5.7‰ to − 6.9‰ and the corresponding δ18OSMOW values ranged from 5.8‰ to 9.1‰, implying that the ore-forming fluid was mainly sourced from magmatic water with a minor amount of meteoric water. Collectively, the evidence indicates that the formation of the Nanyangtian deposit is related to Laojunshan granitic magmatism. [ABSTRACT FROM AUTHOR]

The Badi copper deposit is located in Shangjiang town, Shangri-La County, Yunnan Province. Tectonically, it belongs to the Sanjiang Block. Vapor-liquid two-phase fluid inclusions, CO2-bearing fluid inclusions, and daughter-bearing inclusions were identified in sulfide-rich quartz veins. Microthermometric and Raman spectroscopy studies revealed their types of ore-forming fluids: (1) low-temperature, low-salinity fluid; (2) medium-temperature, low salinity CO2-bearing; and (3) high-temperature, Fe-rich, high sulfur fugacity. The δ18O values of chalcopyrite-bearing quartz ranged from 4.96‰ to 5.86‰, with an average of 5.40‰. The δD values of ore-forming fluid in equilibrium with the sulfide-bearing quartz were from − 87‰ to − 107‰, with an average of − 97.86‰. These isotopic features indicate that the ore-forming fluid is a mixing fluid between magmatic fluid and meteoric water. The δ34S values of chalcopyrite ranged from 13.3‰ to 15.5‰, with an average of 14.3‰. Sulfur isotope values suggest that the sulfur in the deposit most likely derived from seawater. Various fluid inclusions coexisted in the samples; similar homogenization temperature to different phases suggests that the Badi fluid inclusions might have been captured under a boiling system. Fluid boiling caused by fault activity could be the main reason for the mineral precipitation in the Badi deposit. [ABSTRACT FROM AUTHOR]

Some Au deposits in southern Anhui Province have recently been found to be closely associated with Late Mesozoic intrusions. Typical examples include the Huashan Au (Sb) deposit and Au deposits at Zhaojialing, Wuxi, and Liaojia. In order to understand the mechanisms that led the formation of these Au deposits, we make detailed reviews on the geological characteristics of these Au deposits. Specifically, we present new LA-ICP-MS zircon U-Pb dating, along with elemental and Hf isotopic data from the Huashan Au (Sb) deposit. Our data suggests that the Huashan ore-related intrusions were emplaced during the Late Jurassic and Early Cretaceous periods (144-148 Ma). They are characterized by arc-magma features and high oxygen fugacity and are rich in inherited zircons. Zircon U-Pb ages and Lu-Hf isotopes from intrusions suggest that Proterozoic juvenile lithosphere is the main source of these intrusions. The regional geological history implies that lithosphere beneath southern Anhui was produced during a Proterozoic subduction and was fertilized with Au (Cu) in the process. Integrated with the results of previous studies, we inferred that Late Mesozoic intrusions formed by the remelting of the lithosphere could provide the metal endowment for the Au-rich deposits in southern Anhui. [ABSTRACT FROM AUTHOR]

The Shihu gold deposit, located in the middle-south section of the core of the Fuping mantle branch structure, is hosted in the Archean Fuping Group and adjacent to the quartz diorite porphyrite. The gold deposit is the only large gold deposit with reserves of more than 30 tons gold discovered in western Hebei Province so far. In order to constrain the timing of mineralization of this ore deposit, this paper focuses on the isotopic dating of zircon and pyrite. Zircons in gold-bearing quartz veins are magmatic in origin and no hydrothermal zircon has been found in such quartz veins, indicating that zircons were derived from the wall rocks. U-Pb ages of zircons fall mainly in the two domains: 2492 ± 82 and 136 ± 4 Ma, respectively, indicative of the contribution of the Fuping-Group TTG gneiss and Yanshanian igneous rocks, respectively. The Re-Os isotopic compositions of pyrites in the gold-bearing quartz veins yield an isochron age of 127 ± 31 Ma. Combined with other dating results, we suggest that the main metallogenic age of the Shihu gold deposit is 120-127 Ma. [ABSTRACT FROM AUTHOR]

The contiguous region between Guangxi, Guizhou, and Yunnan, commonly referred to as the Golden Triangle region in SW China, hosts many Carlin-type gold deposits. Previously, the ages of the gold mineralization in this region have not been well constrained due to the lack of suitable minerals for radiometric dating. This paper reports the first SIMS U-Pb age of hydrothermal rutile crystals for the Zhesang Carlin-type gold deposit in the region. The hydrothermal U-bearing rutile associated with gold-bearing sulfides in the deposit yields an U-Pb age of 213.6 ± 5.4 Ma, which is within the range of the previously reported arsenopyrite Re-Os isochron ages (204 ± 19 to 235 ± 33 Ma) for three other Carlin-type gold deposits in the region. Our new and more precise rutile U-Pb age confirms that the gold mineralization was contemporaneous with the Triassic W-Sn mineralization and associated granitic magmatism in the surrounding regions. Based on the temporal correlation, we postulate that coeval granitic plutons may be present at greater depths in the Golden Triangle region and that the formation of the Carlin-type gold deposits is probably linked to the coeval granitic magmatism in the region. This study clearly demonstrates that in situ rutile U-Pb dating is a robust tool for the geochronogical study of hydrothermal deposits that contain hydrothermal rutile. [ABSTRACT FROM AUTHOR]

Porphyry Cu and Mo deposits are two economically important types of metal deposits worldwide, but factors controlling their difference remain enigmatic. Compared with the well-studied large porphyry Mo province in the south margin of the North China Block (S-NCB), the origin of newly discovered porphyry Cu deposits in the South Qinling (SQB) is poorly constrained. Integrated zircon LA-ICPMS U-Pb and molybdenite Re-Os ages and geological evidence indicate three stages of magmatism at Lengshuigou: (1) late Neoproterozoic (718 to 704 Ma) quartz diorite + albitite + granite association during the pre-ore stage, (2) 146 to 145 Ma granodiorite porphyry during the syn-ore stage, and (3) 145 Ma granite porphyry during the post-ore stage. Elemental and Sr-Nd isotopic evidence provide important constraints on their magma source. Pre-ore Neoproterozoic quartz diorite + albitite + granite was derived by re-melting of a mixture of crustal and juvenile mantle materials, and stronger fractional crystallization was involved in these ore-hosting intrusions than in contemporary granitoids hosted in the Douling Group. Syn-ore granodiorite porphyry was derived from mantle-derived magma with contributions from different proportions of crustal components. Post-ore granite porphyry was derived mainly from a crustal source. Nearly contemporaneous porphyry Cu and Mo systems were identified in Qinling Province, including the 147-139 Ma porphyry Mo systems in the S-NCB and 150-146 Ma porphyry Cu systems in the SQB. Granitic stocks related to porphyry Cu systems in the SQB are characterized by moderate SiO contents (58.01-69.07 %) and less radiogenic Nd-Hf isotopes (εNd = −3.8 to −6.3, εHf = −4.5 to +1.6), whereas the granitic stocks related to porphyry Mo deposits in the S-NCB have high SiO concentrations (64.00-76.00 %) and more radiogenic Nd-Hf isotopes (εNd = −18.0 to −11.6, εHf = −26.3 to −13.5). In addition, molybdenite from the Chigou and Lengshuigou porphyry Cu deposits in the S-NCB show higher Re contents (77.50-394.3 ppm) than those from nearly contemporaneous porphyry Mo deposits (9.34-49.7 ppm) in the S-NCB. These lines of evidence indicate that a higher proportion of mantle component was involved in the formation of porphyry Cu deposits in the SQB than nearly contemporaneous porphyry Mo deposits in the S-NCB. It is most likely that the nature of the magma source plays an essential role in the differences between porphyry Cu and Mo deposits. [ABSTRACT FROM AUTHOR]

Stratabound deposits are the most abundant and economically significant ore type in the Middle-Lower Yangtze River Valley, one of the most important metallogenic belts in China. The Datuanshan deposit is one of the largest and most representative stratabound Cu(-Mo) deposits in the Tongling district of the Middle-Lower Yangtze River metallogenic belt. All the orebodies of the Datuanshan deposit occur around Mesozoic quartz monzodiorite and are tabular or semi-tabular bodies along bedding-parallel faults within upper Permian to Lower Triassic strata. However, discordant and crosscutting relationships (e.g., the host rocks crosscut by skarn- and quartz-sulfide veins, with alteration halos around the veins) have also been found, especially along the skarn-host contact and orebody-host contact, indicating that skarnitization and mineralization postdated the deposition of the host sediments. The skarn consists mainly of prograde garnet and pyroxene and retrograde alteration assemblages of amphibole, epidote, and chlorite, as well as quartz and sulfides. Electron microprobe analyses show that the garnets and pyroxenes are grossular-andradite and hedenbergite-diopside series, respectively, and all samples plot in the field of typical skarn copper deposits worldwide. Molybdenite samples from stratiform copper ores yield Re-Os model ages of 138.2-139.9 Ma with a weighted mean age of 139.2 ± 0.9 Ma. This is reasonably consistent with the ages of the stratiform Mo ores (138.0-140.8 Ma) and genetically related quartz monzodiorite (135.2-139.3 Ma) in the Datuanshan deposit, indicating that the stratiform Cu and Mo mineralization was contemporaneous with emplacement of the quartz monzodiorite magmas in the Early Cretaceous. Fifteen δS values for sulfides range from −1.8 to +4.7 ‰, with a mean of 0.5 ‰, indicating that the sulfur was derived mainly from a magmatic source. Moreover, the sulfur isotope values of the ores are consistent with those of Mesozoic intermediate-acid intrusions but are different from those of sediments in the Shizishan orefield. Based on these lines of evidence, we conclude that the Datuanshan stratabound Cu(-Mo) deposit is the result of replacement related to Mesozoic magmatic rocks and is not a product of submarine exhalative sedimentary processes. [ABSTRACT FROM AUTHOR]

The Pengshan Sn and Pb-Zn polymetallic deposits are located in the south margin of the Jiujiang-Ruichang (Jiurui) district of the Middle-Lower Yangtze River Metallogenic Belt in South China. Four large deposits include Huangjinwa, Zengjialong, Jianfengpo, and Zhangshiba, the former three are Sn-dominant deposits which occur as stratiform orebodies in the contact zones of the Pengshan granites and within the country rock strata, whereas Zhangshiba consists of stratiform Pb-Zn orebodies within the Precambrian metasedimentary strata. In this study, we present results on zircon U-Pb ages, major and trace elements, and mineral chemistry as well as Sr-Nd-Hf isotope data of the granites, Pb and S isotopes of both the Sn-dominant and Pb-Zn dominant deposits, and U-Pb dating of cassiterite from the Pengshan district. SHRIMP and LA-ICP-MS zircon U-Pb dating shows that the Pengshan granites were emplaced in the Early Cretaceous (129-128 Ma), which is in good agreement with the U-Pb dating (130-128 Ma) of cassiterite from the Jianfengpo Sn deposit. The Pengshan granites consist mainly of weakly peraluminous highly fractionated I-type affinity granitic rocks. Detailed elemental and isotopic data suggest that the granites formed by partial melting of Mesoproterozoic metamorphic basement materials with minor input of mantle-derived melts. The mineral chemistry of biotite demonstrates that the Pengshan granitic magma had a low oxygen fugacity, thereby precluding the tin dominantly partitioning into the rock-forming silicate minerals and favoring accumulation in the exsolved residual liquid during magma crystallization stages. Sulfur isotopes show a relatively heavy sulfur isotopic composition from 5.8 to 17.6 ‰, and no difference for sulfur isotopes between the Sn deposits (5.8-13.4 ‰, Huangjinwa, Zengjialong, Jianfengpo) and the Pb-Zn deposit (mostly 7.1-13.0 ‰, except for one 17.6 ‰, Zhangshiba). The sulfur isotope data of pyrite from the host sedimentary rocks show relatively higher δS values of 22.7-28.7 ‰. Lead isotopes indicate that the granites have higher Pb/Pb, Pb/Pb, and Pb/Pb ratios than the host Precambrian metasedimentary rocks, and the sulfide minerals from the orebodies fall in between them. Again, there is no difference for Pb isotopes between the Sn deposits (Huangjinwa, Zengjialong, Jianfengpo) and the Zhangshiba Pb-Zn deposit. The coincidence in S and Pb isotope compositions for Sn and Pb-Zn deposits suggests that similar sources for these mineralization, possibly derived from a mixed source of the granitic magmas and the Precambrian metasedimentary rocks. These data therefore favor of a magmatic-hydrothermal origin for both the Sn and Pb-Zn polymetallic mineralization in the Pengshan district. [ABSTRACT FROM AUTHOR]

We present Mo isotopic ratios of molybdenite from five porphyry molybdenum deposits (Chagele, Sharang, Jiru, Qulong, and Zhuonuo) and one quartz-molybdenite vein-type deposit (Jigongcun) along the Gangdese metallogenic belt in the Tibetan Plateau. These deposits represent a sequence of consecutive events of the India-Asia collision at different periods. Additional molybdenite samples from the Henderson Mo deposit (USA), the oceanic subduction-related El Teniente (Chile), and Bingham (USA) porphyry Cu-(Mo) deposits were analyzed for better understanding the controls on the Mo isotope systematics of molybdenite. The results show that molybdenite from Sharang, Jiru, Qulong, and Zhuonuo deposits have similar δMo (∼0 ‰), in agreement with the values of the Henderson Mo deposit (−0.10 ‰). In contrast, samples from the Changle and Jigongcun deposit have δMo of 0.85 ‰ to 0.88 ‰ and −0.48 %, respectively. Molybdenite from the El Teniente and Bingham deposits yields intermediate δMo of 0.27 and 0.46 ‰, respectively. The Mo isotopes, combined with Nd isotope data of the ore-bearing porphyries, indicate that source of the ore-related magmas has fundamental effects on the Mo isotopic compositions of molybdenite. Our study indicates that molybdenite related to crustal-, and mantle-derived magmas has positive or negative δMo values, respectively, whereas molybdenite from porphyries formed by crust-mantle mixing has δMo close to 0 ‰. It is concluded that the Mo isotope composition in the porphyry system is a huge source signature, without relation to the tectonic setting under which the porphyry deposits formed. [ABSTRACT FROM AUTHOR]

The Sandaowanzi gold-telluride deposit, with a total reserve of ≥ 25 t of Au and an average grade of 15 g/t, is located in the Great Hinggan Range Metallogenic Belt in NE China. This deposit is the first reported case of a dominantly Au (±Ag)-telluride deposit in this area and it reveals highly economic bonanza Au- and Ag-telluride ores. Ore bodies principally occur in quartz veins and stockworks and minor in disseminations hosted by trachyandesites and andesitic breccias. Four paragenetic stages of mineralization are identified, demonstrating an early deposition of sulfides and subsequent precipitation of tellurides, which are mainly composed by petzite, sylvanite and to a lesser extent, hessite, calaverite, altaite, unnamed telluride (AuAgTe), krennerite, empressite, stützite and coloradoite. Abundant telluride assemblages identified from Sandaowanzi ores are mostly attributed to breakdown of early tellurium-bearing phases (i.e., γ- and χ-phases) during cooling. The deposition of substantial Au-Ag-Te minerals are constructed under physicochemical conditions of T = 240 to 280 °C, pH = 4.39 to 5.64, logfO =-44.8 to -41.8, logfTe =-9.75 to -9.43, logαAu/αAg = −6.87 to -6.56, and gold is mostly scavenged from a HTe-dominant ore-forming fluid. The unusually high Te concentrations in the Sandaowanzi epithermal system are likely attributed to alkaline to calc-alkaline magmatic degassing. [ABSTRACT FROM AUTHOR]

The Tengchong-Lianghe tin district in northwestern Yunnan, China, is an important tin mineralization area in the Sanjiang Tethyan Metallogenic Domain. There are three N-S trending granite belts in the Tengchong-Lianghe area, with emplacement ages ranging from Early Cretaceous to Late Cretaceous and Early Cenozoic. Tin mineralization is spatially associated with these granitic rocks. However, the petrogenetic link between the tin deposits and the host granites is not clear because of the lack of age data for the tin mineralization. We investigate the possibility of direct dating of cassiterite from three typical tin deposits in the Tengchong-Lianghe tin district, using laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). In situ LA-MC-ICP-MS dating of seven cassiterite samples from the Lailishan (LLS-1 and LLS-2), Xiaolonghe (XLH, WDS, DSP, and HJS), and Tieyaoshan (TYS) tin deposits yielded well-defined Pb/Pb-U/Pb isochron ages. To assess the accuracy of the in situ U/Pb dating of cassiterite, Ar/Ar dating of coexisting muscovite (in samples LLS-1, DSP, and TYS) was also performed. The cassiterite in situ U/Pb ages (47.4 ± 2.0, 71.9 ± 2.3, and 119.3 ± 1.7 Ma, respectively) are in excellent agreement with the coexisting muscovite Ar/Ar ages (48.4 ± 0.3, 71.9 ± 1.4, and 122.4 ± 0.7 Ma, respectively). The U/Pb ages of cassiterite combined with the Ar/Ar ages of muscovite indicate that there are three tin mineralization events in this district: the Lailishan tin deposit at 47.4 ± 2.0 to 52 ± 2.7 Ma, the Xiaolonghe tin deposit at 71.6 ± 2.4 to 3.9 ± 2.0 Ma, and the Tieyaoshan tin deposit at 119.3 ± 1.7 to 122.5 ± 0.7 Ma. These ages are highly consistent with the zircon U/Pb ages of the host granites. It is su.ggested that the Cretaceous tin mineralization might have taken place in a subduction environment, while the Early Tertiary tin metallogenesis was in a postcollisional geodynamic setting. [ABSTRACT FROM AUTHOR]

Abstract  The Samgwang mine is located in the Cheongyang gold district (Cheonan Metallogenic Province) of the Republic of Korea. It consists of eight massive, gold-bearing quartz veins that filled NE- and NW-striking fractures along fault zones in Precambrian granitic gneiss of the Gyeonggi massif. Their mineralogy and paragenesis allow two separate vein-forming episodes to be recognized, temporally separated by a major faulting event. The ore minerals occur in quartz and calcite of stage I, associated with fracturing and healing of veins. Hydrothermal wall-rock alteration minerals of stage I include Fe-rich chlorite (Fe/(Fe) ratios 0.74-0.81), muscovite, illite, K-feldspar, and minor arsenopyrite, pyrite, and carbonates. Sulfide minerals deposited along with electrum during this stage include arsenopyrite, pyrite, pyrrhotite, sphalerite, marcasite, chalcopyrite, galena, argentite, pyrargyrite, and argentian tetrahedrite. Only calcite was deposited during stage II. Fluid inclusions in quartz contain three main types of C–O–H fluids: CO2-rich, CO2–H2O, and aqueous inclusions. Quartz veins related to early sulfides in stage I were deposited from H2O–NaCl–CO2 fluids (1,500–5,000 bar, average 3,200) with T htotal values of 200°C to 383°C and salinities less than about 7 wt.% NaCl equiv. Late sulfide deposition was related to H2O–NaCl fluids (140–1,300 bar, average 700) with T htotal values of 110°C to 385°C and salinities less than about 11 wt.% NaCl equiv. These fluids either evolved through immiscibility of H2O–NaCl–CO2 fluids as a result of a decrease in fluid pressure, or through mixing with deeply circulated meteoric waters as a result of uplift or unloading during mineralization, or both. Measured and calculated sulfur isotope compositions (δ34SH2S = 1.5 to 4.8‰) of hydrothermal fluids from the stage I quartz veins indicate that ore sulfur was derived mainly from a magmatic source. The calculated and measured oxygen and hydrogen isotope compositions (δ18OH2O = −5.9‰ to 10.9‰, δD = −102‰ to −87‰) of the ore-forming fluids indicate that the fluids were derived from magmatic sources and evolved by mixing with local meteoric water by limited water–rock exchange and by partly degassing in uplift zones during mineralization. While most features of the Samgwang mine are consistent with classification as an orogenic gold deposit, isotopic and fluid chemistry indicate that the veins were genetically related to intrusions emplaced during the Jurassic to Cretaceous Daebo orogeny. [ABSTRACT FROM AUTHOR]

Abstract  The Røros district is a pyrite-rich polymetallic sulfide orefield in the southeastern part of the Trondheim region, Central Norwegian Caledonides. All of the ore deposits at Røros are hosted within a Cambrian to Silurian succession that was deformed and metamorphosed at lower greenschist to lower amphibolite facies conditions during the Caledonian orogeny. Samples from five individual deposits across the orefield have been analyzed using a combination of reflected light petrographic observation, orientation contrast imaging, and electron backscatter diffraction. Results indicate that, whereas samples from each ore deposit have a variety of different textures, all of them preserve plastic deformation in pyrite grains that occurred at peak metamorphic conditions characterized by the development of internal lattice misorientation within pyrite grains and low-angle (∼2°) dislocation walls. These observations indicate that the principal deformation mechanisms at peak metamorphic conditions were dislocation glide and creep. The preservation of brittle fracturing represents later overprinting events. [ABSTRACT FROM AUTHOR]

The article discusses a study that focuses on the petrogenesis and mineralization of the Paodaoling gold deposit in Guichi Ore cluster region in the Middle-Lower Yangtze Metallogenic Belt in China. Topics discussed include types of mineralized alterations such as carbonatization, chloritization and pyritization; percentage of silica, alumina, potassium oxide revealed in geochemical analysis and hydrothermal transformation in the porphyry deposits.