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[Display omitted] • Co is primarily enriched in Fe-Ti ores and olivine pyroxenites. • Co is mainly hosted within cobaltite and pentlandite. • Co exists as independent Co minerals, via isomorphism, or in microscopic grains. • Sulfide-silicate melt immiscibility is the key process enriching Co. Magmatic Fe-Ti oxide deposits are recognized as a potential significant source of Co. However, the distribution, occurrence state and enrichment mechanism of Co within these deposits are not well understood. The Hongge deposit, one of the world's largest Fe-Ti oxide deposits, has an estimated Co reserve of 488,400 tons and an annual production of Co concentrates of 20,000 tons. Based on comprehensive analyses across various scales from lithologies to rocks and minerals, this study aims to elucidate the occurrence state and enrichment mechanism of Co in Fe-Ti oxide deposits. Among different rock types, the highest concentrations of Co are observed in massive ores, with an average of 280 ppm, followed by disseminated ores, olivine pyroxenite, pyroxenite, and gabbro. In silicate and oxide minerals, the abundance of Co decreases in the following order: olivine > magnetite > ilmenite > amphibole > pyroxene > apatite and plagioclase. Among sulfide minerals, the Co content is ranked as follows: cobaltite (with Co contents ranging from 18.42 % to 25.80 %) > pentlandite > pyrite > pyrrhotite > chalcopyrite. Cobalt occurs as three primary forms: (1) an independent mineral, such as cobaltite (As 0.99∼1.10 Co 0.55∼0.74 Ni 0.20∼0.37 S); (2) isomorphous substitution for Fe, Mg and V; (3) microscopic inclusions in magnetite and pyrrhotite. The processes contributing to the enrichment of Co include fractional crystallization, sulfide-silicate immiscibility, and hydrothermal alteration. Sulfide-silicate immiscibility plays a predominant role in the Co enrichment. [ABSTRACT FROM AUTHOR]

[Display omitted] • recycled oceanic sediment was involved in source of the parental magma. • PGE depletion in the parental magma before sulfide saturation. • sulfide-silicate magma interactions in the deep chamber play an important role. • significant PGE mineralization potential is expected in the staging magma chamber. The Nanke Ni-Cu sulfide deposit is situated within the Jinping-Song Da region of the Emeishan large igneous province. A sill-like body of olivine pyroxenite intruding Late Silurian strata hosts the deposit, which consists of massive, net-textured and disseminated sulfide ores. The predominant sulfide minerals are pyrrhotite, pentlandite and chalcopyrite, together they constitute over 90 % of the sulfide mineral assemblage. The Nanke deposit is notable for its significant negative Nb-Ta anomalies and enriched ε Nd (t) values (−4.4 to −6.2), like the coeval Emeishan picrite and basalt in this region. Mixing calculations indicate that these geochemical features are due to the involvement of recycled oceanic sediment in the mantle sources, rather than shallow-level crustal contamination. The ores of Nanke deposit contain relatively high contents of Ni (0.20 to 4.2 wt%) and Cu (0.06 to 1.37 wt%) but low platinum-group element (PGE) contents (1.56 to 37 ppb). They exhibit Cu/(Pd × 1,000) ratios ranging from 191 to 5897, suggesting that PGE depletion occurred within the parental magma before it reached sulfide saturation. The Ni/Cu ratios of the ores vary from 0.76 to 33, averaging 13.9 for massive ores and 3.96 for net-textured and disseminated ores, which is higher than those of the Baimazhai deposit and Ban Phuc deposit. This suggests that the PGE depletion in the Nanke deposit cannot be attributed to sulfide saturation triggered by fractional crystallization alone. The sulfide ores display a mantle-like δ34S range from −1.09 to + 0.03 ‰, supporting the interpretation that the parental magma underwent sulfur isotope exchange between new primitive magma and pre-existing sulfide liquid. Mass balance calculations indicate that most PGEs and some Ni were transferred from the magma to the pre-existing sulfide liquid during the reaction, resulting in a final magma with PGE content similar to the composition of PGE-depleted basalt and picrite in this area. The sulfide saturated from the magma with R-factors of 200-1000, forming the Nanke deposit. The PGE enrichment in the pre-existing sulfide liquid through reactions at greater depths suggests that exploration for PGE deposits at deeper levels is warranted. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three generations of tetrahedrite have been recognized from Fe-Cu stage to Pb-Zn stage. • Selenium mainly occurs in pyrite and tetrahedrite, while Te occurs as both independent mineral and isomorphism. • High temperatures contribute to the enrichment and precipitation of Se, but do the opposite effect on Te. • Te and Se mineralization have similar regularity in porphyry-skarn deposits in the MLYB. The Jilongshan Au-Cu skarn deposit is located at the Jiurui ore district of the Middle-Lower Yangtze River metallogenic belt (MLYB), which is a significant metallogenic belt for dispersed elements. The Jilongshan deposit hosts abundant critical metal elements (e.g., Se, Te, and Bi) and shows potential for the comprehensive utilization of these critical mineral resources. This study examines the mineralogical textures and compositions of sulfides and sulfosalts from the Jilongshan deposit through EPMA, TIMA, and LA-ICP-MS analyses to clarify the nature of the occurrence and distribution of Se and Te. Based on the host rocks, the ores can be divided into porphyry-hosted, marble-hosted, and skarn-hosted types. Selenium content is significantly higher in porphyry-hosted and skarn-hosted ores compared to marble-hosted ore, while Te is most abundant in marble-hosted ore. Apart from rare minerals such as clausthalite (PbSe), hessite (Ag 2 Te), and hedleyite (Bi 7 Te 3), Se and Te predominantly occur as isomorphism within pyrite (∼70 %) and tetrahedrite (∼20 %). On the basis of mineral assemblages and textures, tetrahedrite can be recognized as three generations, including Ttr1 (replacing Fe-Cu sulfides), Ttr2 (intergrown with Pb-Zn sulfides), and Ttr3 (replacement of last pyrite). Selenium is enriched in minerals precipitated in the Fe-Cu stage, including hydrothermal pyrite, chalcopyrite, and Ttr1, with the average of 345 ppm, 183 ppm, and 592 ppm, respectively, while Te mainly concentrates in minerals formed in the Pb-Zn stage, such as galena (143 ppm), Ttr2 (3112 ppm), and Ttr3 (489 ppm). These findings align with previous studies on the Se-Te relationship and may indicate that Se is more likely to be enriched at a higher temperature, while Te exhibits the opposite trend. The variation in sulfur fugacity within fluid systems may also play a role in the enrichment of these critical elements. Additionally, the regional distribution and enrichment of Se and Te in the porphyry-skarn deposits of the MLYB also shows certain regularity. Selenium is more likely to be enriched in high-temperature porphyry ores, while Te is most abundant in relatively low-temperature interlayer ores. [ABSTRACT FROM AUTHOR]

[Display omitted] • NW–SE trending ductile–brittle Chitradurga shear zone controls gold mineralization. • Carbonatization, chloritization, and sulfidation are the major alterations. • Gold/sulfide minerals are confined to altered & deformed rocks. • Fe-rich chlorites are closely associated with gold/sulfides in the proximal zone. • A temperature range of ̴ 306–326 °C for hydrothermal activity is proposed. The gold mineralization at Paramanahalli (Chitradurga, Karnataka) in the Archean Greenstone Belt of Western Dharwar Craton, India, is structurally controlled and similar to many greenstone-hosted orogenic gold deposits across the world. The volcano-sedimentary rock sequences of the Hiriyur Formation of the Chitradurga Group are the host rocks related to gold mineralization. These litho-units were subjected to greenschist facies metamorphism, later deformed and altered by hydrothermal fluids. Detailed petrographic studies indicate that the rocks experienced chloritization, carbonatization, silicification, and sulfidation due to wall rock-fluid alterations. The prominent wall rock alteration assemblage is characterized by the presence of chlorite (Mg-rich), ilmenite, albite, and quartz-1 in the distal zone and quartz-2, chlorite (Fe-rich), biotite, ankerite in the proximal zone with a significant amount of sulfide minerals and gold. Three major stages of mineral formation have been identified: albite-1, Mg-rich chlorite, quartz-1, magnetite, and ilmenite formed during the regional metamorphism and deformation stage (pre-ore stage). Fe-rich chlorite, annite, quartz-2, pistomesite, ankerite, rutile, pyrite, chalcopyrite, pyrrhotite, and gold during the mineralization stage (syn-ore stage) and albite-2, calcite and goethite formed during the post mineralization stage (post-ore stage). The development of different types of twinning in calcite indicates the deformation temperature, around 150–300 °C. The temperature range of approximately 306–326 °C is the temperature of hydrothermal fluids involved in gold mineralization based on chlorite thermometry. Kink folds and strain fringes in altered wall rocks indicate ductile deformation followed by brittle deformation in the area. [ABSTRACT FROM AUTHOR]

[Display omitted] • SWIR spectral parameters of white mica can reflect the physicochemical conditions. • The shift in wavelength is predominantly controlled by Tschermak substitution. • The longer Pos2200 and higher IC values of white mica can distinguish orebodies. The Xiaoqinling-Xiong'ershan region, a prominent component of the East Qinling Belt, is renowned worldwide for its molybdenum and gold ore fields. Moreover, with gold reserves of at least 1300 tons, it is also China's major gold mining province, second only to Jiaodong. Seated in eastern center of the Xiong'ershan area, the Xiaonangou gold deposit has an estimated gold reserve of over 60 tons and is characterized by disseminated gold in altered rocks. Based on detailed petrographic investigation, coupled with an analysis of crosscutting relationships, there are three stages of hydrothermal alteration and mineralization: pre-ore K-feldspar + quartz (stage Ⅰ), ore quartz + ankerite + disseminated pyrite + polymetallic sulfide (stage Ⅱ), and post-ore quartz + carbonate (stage Ⅲ). As revealed by a systematic analysis of short wavelength infrared (SWIR) spectroscopy, four main types of alteration minerals exist, including white micas, clay minerals, chlorite, and carbonate minerals. In the ore body, white micas mainly developed in stage Ⅱ, and slightly occurred in stage Ⅰ. The clay minerals and chlorite usually developed in the banded alteration zones outside the orebody. Most of the carbonate minerals, including calcite and dolomite, mainly developed in stage Ⅲ, but the ankerite was associated with disseminated pyrite, quartz and polymetallic sulfides in stage Ⅱ. Of these, white micas were recognized as the most abundant hydrothermal alteration minerals, which were observed to be widely distributed within alteration zones in the Xiaonangou gold deposit. The SWIR parameters and its spatial variation of white mica indicate that the Al-OH absorption positions (Pos2200) exhibit a drifting tendency towards longer (>2205 nm) wavelengths in the ore body vicinity. Additionally, there is a discernible increase in illite crystallinity (IC values) in the same region. The temperature, redox, and pH conditions for associated fluids can be reflected through characterization of these parameters. Furthermore, it demonstrates that the ore-proximal zones are situated in a relatively oxidized, alkaline, and high-temperature environment in the Xiaonangou gold deposit. According to the electron probe microanalysis (EPMA) results, two distinct end members exist in white mica: a Si-poor, Al-rich muscovite and an Al-poor, Si-, Fe-, and Mg-rich phengite. The Si, ivAl, viAl, Mg, Fe, and Ti elements exhibit a linear correlation with the wavelength of Pos2200, demonstrating that the shift in wavelength of white mica is predominantly controlled by Tschermak substitution (ivSivi(Mg，Fe) ↔ivAlviAl). The application of spatial variation in the SWIR spectral parameters along with geochemical properties of white mica facilitates the effective guidance of mineral exploration. In comparison to other deposits, it can be concluded that the longer (>2205 nm) wavelength of the Pos2200 along with the higher IC values (>1.4) of white mica are applicable as valid vectors towards gold mineralization in the Xiaonangou gold deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • Au- and Mo-related hydrothermal rutiles are both present in the Laowan deposit. • The Au-related rutiles are significantly incorporated W, Nb, and Ta. • The Mo-related rutiles are featured by Sn, W, and Nb. • The Au- and Mo-related rutiles formed from different fluid systems. The Laowan deposit is a recently discovered large lode-gold deposit with a Au reserve >208 t in the Tongbai Orogen of Central China. This Au deposit is characterized by the co-occurrence of stockwork-type Mo mineralization. Hydrothermal rutiles are present both in the altered rock-type gold ores and in the alteration halos around the fluorite-K-feldspar-quartz Mo veins. A detailed investigation of the mineralogical, textural, and chemical analyses (EPMA and LA–ICP–MS) of the Au- and Mo-related rutiles was carried out in this study. Au-related rutiles formed during silicification and sericitization, intergrown with a hydrothermal mineral assemblage of pyrite + chalcopyrite + electrum + sericite + quartz + calcite + REEPO 4 minerals, whereas Mo-related rutiles formed during sericitization and silicification closely associated with sericite + quartz + apatite + calcite + molybdenite + other Fe-Cu sulfides. Both rutiles formed via hydrothermal breakdown of metamorphic titanites in the host rocks of garnet-epidot-amphoble–quartz schist. The formation mechanism involves coupled dissolution-reprecipitation of CaTiSiO 5 (titanite) + CO 2 -rich fluid = TiO 2 (rutile) + CaCO 3 (calcite) + SiO 2. The textural features show that most of the Au-related rutiles nucleate and grow at the original textural position of the precursor titanites, suggesting a mechanism of coupled dissolution and in situ precipitation due to relatively low mobility of Ti. The Mo-related rutiles grow in a microenvironment locally enriched in Ti due to the small-scale mobilization of Ti released during titanite dissolution, suggesting a relatively high solubility of Ti. These results indicate that the Mo-mineralized fluid system probably contains more halogens (particularly F) than the Au-mineralized fluid system does because TiO 2 solubility and mobilization increase with increasing halogen concentration in the fluid system. The Au-related rutiles are characterized by enrichment of W, Nb, and Ta, whereas the Mo-related rutiles are characterized by enrichment of Sn, W, and Nb. The mass balance estimation indicated that the Au-related rutiles retained most of the trace elements released from the breakdown of titanites and significantly incorporated W and, to a lesser extent, Nb and Ta from the hydrothermal fluid during rutile precipitation. The Mo-related rutiles incorporated significant amounts of Sn, W, Nb, and, to a lesser extent, Th and Pb from the hydrothermal fluid and Sc, V and Cr from other mafic minerals, such as amphibole, during hydrothermal alteration. The compositional fingerprints of hydrothermal rutiles indicate that the Mo-mineralized fluid contained Sn, W and Nb and more halogen (particularly F), which are distinguished from the Au ore-forming fluid, which contained significant amounts of W but less Nb and Ta and lower amounts of halogen. The Au- and Mo-related rutiles formed from two different fluid systems during different periods (∼140 Ma and ∼130 Ma), recording the overprinting of two separate magmatic-hydrothermal fluid events in the same deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Axile deposit is an orogenic-type gold deposit. • The deposit formed much later than the ore-hosted intrusions. • The ore-forming fluids were mainly derived from the sediments. • The Chinese Altai is an orogenic-type Au-Te-Bi mineralization belt associated with regional metamorphism and shearing events. Unlike the gold deposits typically hosted in metamorphosed volcanic-sedimentary sequences, the recently discovered Axile gold deposit (over 13 t Au at 5.35 g/t) is a unique example in the Chinese Altai for evaluating the genesis of intrusion-hosted lode gold deposits in metamorphic terranes. The orebodies in this deposit occur as quartz veins and altered tectonites hosted in the sinistrally sheared quartz diorite and biotite granite zones in the Habahe intrusion. The quartz vein-type ores are composed of quartz-pyrite veins and quartz-polymetallic sulfide veins, in which gold-tellurides also occur. The altered tectonites, spatially associated with the quartz veins, are composed of deformed and altered rocks of quartz diorite and biotite granite. Main alterations include quartz, sericite, calcite, chlorite, albite, pyrite, chalcopyrite, and gold-tellurides. Two types of fluid inclusions are identified in the ores, i.e., (1) carbonic-aqueous (C-type) and (2) aqueous (W-type), with the C-type being dominated. These fluid inclusions yield salinity ranging from 3.6 to 9.0 wt% NaCl equivalent and homogenization temperatures in the range of 249 − 387 ℃, suggesting a typical mesothermal NaCl-CO 2 -H 2 O system. The Axile deposit thus corresponds to an orogenic-type gold deposit. The hydrothermal titanites in the auriferous quartz-pyrite veins yield in situ U-Pb ages around 278.4 ± 2.4 Ma (MSWD = 3.1, 2σ), which constrain the gold mineralization timing as Permian. The mineralized quartz diorite and biotite granite yield zircon U-Pb ages of 377.0 ± 1.0 Ma (MSWD = 0.1; 1σ) and 394.0 ± 1.2 Ma (MSWD = 0.4; 1σ), respectively, which show that the ore-hosting intrusions were emplaced in the Devonian, obviously earlier than the gold mineralization. The light δ13C V-PDB values (−15.5 ‰ to −6.7 ‰, average −10.7 ‰) of the CO 2 extracted from the fluid inclusions display a significant contribution from the organic carbon in sediments. Given the sedimentary rocks underwent Permian greenschist to amphibolite facies metamorphism in the Chinese Altai, accompanied by the synchronous structural deformation and shearing activities, it could be concluded that the Axile gold deposit is formed by a shear zone-controlled mesothermal system that originated from metamorphic-devolatilization. The Chinese Altai Orogen is an orogenic-type gold metallogenic belt, containing both the intrusion- and metamorphic rock-hosted gold deposits, illustrated by a consistent genetic model. [ABSTRACT FROM AUTHOR]

[Display omitted] • Tellurium is mainly hosted in pyrite as mineral inclusions, whereas Se is mainly hosted in chalcopyrite and bornite replacing S. • Positive correlations between Pb and Au suggest a Pb melts collecting Au model. • In porphyry-skarn deposits of the Mid-Lower Yangtze River belt, Te is typically hosted in pyrite, Se in chalcopyrite, Co in both pyrite and sphalerite, and Au in chalcopyrite. In recent years, an increasing number of studies have reported the enrichment of Te, Se, and Co in magmatic-hydrothermal deposits in the Mid-Lower Yangtze River metallogenic belt (MLYRB), especially in Au-rich deposits. The Jiguanzui deposit, a representative porphyry-skarn Au-Cu deposit in the MLYRB, Eastern China, is characterized by significant critical metal (Te, Se, Co) association. Based on previous studies on critical metals distribution, this study presents trace element geochemistry of various sulfide minerals (chalcopyrite, bornite, sphalerite, molybdenite) through LA-ICP-MS analysis, aiming to reveal the distribution and modes of occurrences of Te, Se, Co, and Au among sulfide minerals in the Jiguanzui Au-Cu deposit. Analytical results indicate that, except for molybdenite, which hosts high concentrations of both Te and Se, pyrite and chalcopyrite generally have higher Te contents than bornite and sphalerite, whereas bornite and chalcopyrite exhibit relatively high Se concentrations. Cobalt and Au are dominantly hosted in pyrite and chalcopyrite, respectively, although the highest Au concentration up to 14 ppm was tested in pyrite. Principal component analysis of trace element contents, time-resolved LA-ICP-MS signal depth profiles, and trace element correlations suggest that Te is generally incorporated as silver and bismuth telluride mineral inclusions in the sulfides, whereas Se and Co are incorporated into the lattice of sulfide minerals. The intimate Pb-Bi-(Cu)-Au associations suggest that tiny mineral inclusions of native Au coexisting with either Cu-Bi sulfosalts or Pb sulfides or sulfosalts. Comparative analysis of the distribution patterns of Te, Se, Co, and Au in porphyry-skarn deposits within the MLYRB suggest that pyrite is the main Te-hosting sulfide mineral, whereas chalcopyrite is the major host for Se, which means Te hosted in pyrite is difficult to recover under current technologies. Pyrite and sphalerite are the major hosts of Co, and chalcopyrite is the main Au-bearing sulfide mineral in the deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Mamuniyeh Cu deposit is located in the central part of the (UDMA), Iran. • Mineralization hosted by Eocene volcanic and Oligo-Miocene intrusions. • Cu Mineralization controlled by NW-SE faults, showing quartz-sulfide-oxide veins. • The ore fluids are low temp / salinity, from magmatic origin mixed with meteoric waters. • Mamuniyeh has been categorized as low-sulfidation epithermal deposits. The Mamuniyeh Cu deposit is located in the central part of the Urumieh-Dokhtar Magmatic Arc (UDMA), 10 km south of the city of Mamuniyeh, Iran. Mineralization is controlled by faults with a NW-SE trend and hosted within an Eocene volcanic sequence and Oligo-Miocene hypabyssal calc-alkaline monzonitic and gabbroic bodies. Quartz + chalcopyrite veins are most abundant and high-grade ore containing up to 5 wt% Cu, although quartz + pyrite veins have the most abundant sulphide content. In addition, quartz + chalcopyrite + specular hematite ± pyrite veins/veinlets are another common mineralized assemblage in the Mamuniyeh copper deposit, with pyrite, chalcopyrite, bornite, and oxide minerals (specular hematite, titanomagnetite, and magnetite) typical of the hypogene stage. Chalcocite, covellite, and dignite also formed at the margins of primary sulphides in the supergene (paleoweathering) stage. The mineralized veins exhibit colloform, crustiform, open space-fillings, replacements, and dissemination textural characteristics associated with mineralizing assemblages with silicification, argillization, chloritization, and sericitization assemblages. The salinity for L > V fluid inclusions is between 1.74 to 11.7 wt% NaCl and for (V > L) inclusions between 1.7 to 11.4 wt% NaCl. The average homogenization temperature and salinity for quartz + chalcopyrite + pyrite veins is 186 °C and 4.9 wt% NaCl. In the quartz + chalcopyrite assemblage an average of 185 °C and 4.5 wt% NaCl and for quartz + chalcopyrite + specularite ± pyrite (QCSP) an average of 195 °C and 5.59 wt% NaCl was determined. In these three vein types, the fluid density has almost identical values ranging from 0.8 to 1.0 g/cm3. The mineralizing system evolved in two-stages; the first metal precipitation occurred at less than 1 km of crustal depths and second metal deposition stage at shallower crustal levels (less than 500 m). Although it appears that the boiling process occurred within the fluids of the area, the primary factor contributing to Cu mineralization was influenced by fluidmixing processes. The δ18O and δD values of ore fluids computed vary from + 6.08 to −0.50 ‰ and −92 to −71 ‰, respectively, indicative of the blending of oxidizing and cooler meteoric waters with primary magmatic fluids. Calculated values of δ34S of H 2 S in equilibrium with chalcopyrite ranges from −7.6 to −1.9 ‰ and H 2 S in equilibrium with pyrite ranges from −7.1 to −3.8 ‰, respectively; this is consistent with monzodiorite to gabbro as the magmatic sulphur source for copper mineralizing fluids. Furthermore, the QCSP vein data align more closely with primary magmatic water compared to other veins, suggesting that precipitation occurred mainly from magmatic fluids, which experienced depletion in δ18O due to mixing with meteoric waters (shallow oxygenated ground waters), which caused sulphide deposition. The geochemical features for these magmas show that contamination with crustal materials occurred during the ascent of the parent magma, as well as the role of suprasubduction fluids released from the subducting plate in mantle metasomatism. Based on all evidence, Cu mineralization in the Mamuniyeh deposit has been categorized as a low-sulphidation epithermal-type system, which formed during active magmatism in the central part of UDMA. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four types of pyrite are identified from two styles of gold mineralization. • All types of pyrite contain low lattice-bound gold. • Deep-seated magma may play a key role for the main mineralization. • The new metallogenic model with two episodes of mineralization has been established. The Kateba'asu gold deposit, situated in the Western Tianshan of China, is one of the most significant discoveries in the world-class Tianshan gold belt. The deposit features two distinct mineralization styles. The early, subordinate skarn-type copper–gold mineralization occurs in the contact zone between monzogranite, diorite, and Silurian limestone, composed of garnet, diopside, epidote, chalcopyrite, pyrite, and gold. The later, primary lode-gold mineralization is hosted in the altered monzogranite characterized by pervasive quartz-pyrite-sericite-chlorite-K-feldspar alteration and a well-develped veining systems. Pyrite is the dominant sulfide mineral related to gold mineralization in the Kateba'asu gold deposit, with four types identified: Py0 from the early skarn copper–gold mineralization, and Py1 to Py3 from the later lode-gold mineralization. All types of pyrite are homogeneous and contain very low levels of lattice-bound gold. Py0 is euhedral and fine-grained, with relatively high Cu, Au, Co, and Ni contents, and displays a magmatic sulfur isotopic signature with δ34S ranging from 0.8 to 4.3 ‰. Py1 occurs as euhedral to subhedral, coarse-grained crystals within pyrite-quartz veins with higher concentrations of Co and Ni. Py2, which develops in the quartz-pyrite veins, is medium to coarse-grained and contains elevated levels of As, Cu, Zn, and Bi relative to Py1. Py3, found in polymetallic sulfide veins of the main lode-gold stage, is anhedral and medium to fine-grained with higher contents of As, Ag, Cu, Zn, Se, Te and lowest Co and Ni concentrations compared to Py1 and Py2. The positive correlations between Au-Te, Au-Bi, Au-Cu, and Pb-Bi across all pyrite types, along with the presence of visible gold in Py3, indicate that most gold occurs as micro-/nano-sized inclusions and as fissure gold. The δ34S values of Py1, Py2, and Py3 (7.6 to 11.8 ‰, 10.1 to 12.6 ‰, and 9.8 to 12.4 ‰, respectively) were attributed to an initial magmatic source and mixed with external sulfur subsequently from the wall rocks. The H and O isotopic compositions (δD H2O = −84.1 to −93.5 ‰; δ18O H2O = 1.8 to 6.6 ‰) of quartz from the lode-gold mineralization imply that ore-forming fluids were predominantly of magmatic origin, with a additional contribution from meteoric water. Taken together, a two-episode mineralization model was proposed for the formation of the Kateba'asu gold deposit. The early skarn mineralization stage is associated with the emplacement of diorite during the Early Carboniferous. In contrast, the subsequent lode-gold mineralization, occurring between the Late Carboniferous and Permian periods, represents a overprinted magmatic-hydrothermal gold system potentially linked to a deep-seated magmatic intrusion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Samples are Fe-rich sulfides with different oxidation degrees from the Wocan-1 hydrothermal field, Carlsberg Ridge. • Fe (oxyhydr)oxides are the oxidation products of sulfides, with Fe-Si (oxyhydr)oxides precipitating from low-temperature hydrothermal fluids. • Three Fe (oxyhydr)oxides associate with the oxidation of different Fe-sulfide minerals. • Fe (oxyhydr)oxides can not only retain Cu and Zn released by the sulfide oxidation, but also scavenge Cu from seawater. • The release of Pb, As, Mo and Co exceeds the retention during the oxidation, which has the potential to damage the local ecosystem. Hydrothermal sulfides undergo complex oxidation process under seawater conditions, which has the potential to impact resource values and marine environments. However, the oxidation process is not fully explored, particularly regarding the transformation of minerals and the behavior of metals. In this paper, we conducted detailed mineralogical and geochemical analyses on a series of samples with varying degrees of oxidation, collected from the Wocan-1 hydrothermal field, Carlsberg Ridge, Northwest Indian Ocean. The principal purpose is to illuminate the formation and transformation of Fe (oxyhydr)oxides, and further to reveal the migration and redistribution of key metals throughout the oxidation process. We identified four types of Fe(−Si) (oxyhydr)oxides with two distinct formation mechanisms. Three Fe (oxyhydr)oxides are the direct oxidation products of pyrite and marcasite, while Fe-Si (oxyhydr)oxide precipitates from low-temperature hydrothermal fluids. Thin Fe (oxyhydr)oxide forms as the secondary product of euhedral pyrite at the early stage of oxidation. Pseudomorphic Fe (oxyhydr)oxide with low Fe contents, occurs as the replacement of euhedral marcasite. Filamentous Fe (oxyhydr)oxide, enriched in trace metals, is attributed to the uniform oxidation of subhedral pyrite-marcasite intergrowth. Moreover, major and trace elements occur multiple migrations and redistributions among primary sulfides, secondary products, and seawater. Notably, Fe (oxyhydr)oxides, through the sequestration mechanism, not only retain Cu and Zn released by the oxidation of primary sulfide minerals, but also scavenge Cu from seawater. However, the dissolution of Pb, As, Mo, and Co exceeds the amount retained during the oxidation, indicating that the potential release of toxic metals into the environment could pose a threat to the local ecosystem. These new insights can provide an initial foundation for the effect of submarine oxidation on economic values of sulfides and ecological environments of deep sea. [ABSTRACT FROM AUTHOR]

[Display omitted] • Major compositions of epidote may be affected by precursor minerals and fluid composition. • Trace elements may be affected by coprecipitating minerals and precursor allanite. • General patterns of trace elements in skarn epidote may indicate orebodies' direction. • As and Sb of epidote correlate with Cu tonnage or distance to magmatic-hydrothermal center. Epidote is a common alteration phase in magmatic-hydrothermal deposits. It has been widely used as an indicator for vectoring mineralization centers and fertility assessments for porphyry ore deposits. However, whether epidote from skarn deposit without significant porphyry-style mineralization can also serve as an exploration indicator remains unclear. Major and trace elements of epidote from the quartz monzodiorite (porphyry) (QMD), endoskarn, Cu-Fe ore, and exoskarn/marble at Tonglushan were analyzed by electron microprobe analysis (EMPA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to constrain their variations across the deposit. The EMPA results suggest that the major compositions (e.g., Al, Fe, and Mn) of epidote are more likely to be affected by precursor minerals such as plagioclase, garnet, diopside, and features of fluid composition (e.g., f O 2 , temperature, and Fe3+ abundance). Epidote trace elements, however, may controlled by coprecipitating minerals such as sulfides and magnetite, which may strongly enrich in certain elements (e.g., As, Sb, Co, Ti, and V) relative to the epidote, as well as precursor allanite which has significantly elevated trace elements (such as As and V) than the successor epidote replacement. The contents of Na, Mg, Mn, Co, and Sn in epidote show a general increase from QMD, through endoskarn, to Cu-Fe ore and then decreasing to exoskarn/marble whereas that of Sc, V, Y, Zr, Sb, and total REE show an opposite trend. The general patterns of these trace elements in skarn epidote may potentially indicate the direction of orebodies. The strong-moderate linear correlation (R2 = 0.76 to 0.93) of As and Sb contents in epidote with the tonnage of Cu or distance from the magmatic-hydrothermal center demonstrates their potential as a quantitative evaluation tool. In general, the trace element contents of skarn epidote are expected to provide critical information for skarn deposit exploration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phreatomagmatic brecciation linked to granite porphyry formed Haopinggou breccia. • S isotopes and monazite 206Pb/238U ages confirm magmatic origin. • Structural weaknesses and fluidization drive NW–SE breccia clast movement. Breccia-hosted Au deposits within the North China Craton (NCC) exhibit a complex genesis, with some breccias being genetically linked to Au mineralization and others unrelated. Understanding the origin of these breccias is crucial for elucidating the genesis of associated ore deposits and guiding exploration strategies. The Haopinggou deposit in the Xiong'ershan district, on the southern margin of the NCC, comprises quartz-carbonate vein-hosted Ag–Pb–Zn–Au deposits and related breccia pipe in metamorphic rocks of the late Archean to early Paleoproterozoic Taihua Group. The origin of the Haopinggou breccia is crucial to understand the Xiayu Ag-Pb-Zn-Au mineralization (5640 t Ag). In this study, we examine the genetic relationship between breccia and Ag‒Pb‒Zn‒Au mineralization, drawing on new insights from the characteristics of the Haopinggou deposit, breccia features, breccia‒hosted Au mineralization, and isotopic data. These findings enhance our understanding of the Haopinggou Ag‒Pb‒Zn‒Au hydrothermal systems and refine exploration models for discordant breccia pipes. Recent underground tunnel surveys and drill-core logging reveal a close spatial link between the breccia and hidden granite porphyry. Juvenile magmatic clasts (granite porphyry) and cement (K-feldspar and quartz crystallized from granite porphyry) are present in the breccia pipe above a granite porphyry apophysis, indicating that the breccia was formed by phreatomagmatic brecciation caused by emplacement of the granite porphyry. Fluidization at the cm- to 100-m-scale reveals that the movement direction of clasts inside the breccia pipe was from northwest to southeast after crypto-explosion, creating a northwest-trending breccia zone. Anhedral monazite (131.2 ± 7.6 Ma) encapsulated in pyrite from the breccia constrains the upper limit of brecciation. The δ34S values of pyrite in rock flour and hydrothermal cements range from 3.8 ‰ to 5.3 ‰ (mean: 4.8 ‰) and 2.7 ‰ to 7.5 ‰ (mean: 5.2 ‰), respectively, with δ34S-sphalerite in hydrothermal cement ranging from 5.7 ‰ to 6.1 ‰ (mean: 5.9 ‰) and δ34S-chalcopyrite ranging from − 0.9 ‰ to 5.6 ‰ (mean: 2.9 ‰). The S isotope characteristics of vein-hosted and breccia-hosted mineralization zones are consistent, with complete alignment of the sulfide assemblages and alteration features. These pieces of evidence collectively indicate that both vein- and breccia-hosted mineralization zones are products of magmatic activity. The metallogenic model for the Haopinggou breccia pipe underscores its unique formation mechanism, driven by pre-existing northwest-striking structural weaknesses and fluidization. This model implies a predominant northwest‒to‒southeast transport of clasts and raises the hypothesis of an underlying porphyry‒type Au mineralization system at depth. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ore-causative granodiorite of the Lianhuashan Cu deposit was emplaced at 252.8 ± 1.8 Ma. • Primary magmas of the adakite-like granodiorite originated from partial melting of the thickened lower crust following closure of the Paleo-Asian Ocean. • New fluid inclusion and H–O–S–Pb isotope data were obtained. • Ore fluids and metals were derived principally from a magma source. The medium-sized Lianhuashan Cu sulfide deposit is located in the southern Xing'an Range of Inner Mongolia, NE China. The zoned massive sulfide vein ores are hosted mainly in the Permian Dashizhai Formation, and the ore veins are controlled by NW–NNW-trending structures. The ore-forming process comprises four stages: arsenopyrite–quartz (I); chalcopyrite–pyrite–quartz (II); pyrite–chalcopyrite–sphalerite–galena–quartz (III); and ore-barren sulfide–quartz–carbonate (IV). Three types of fluid inclusions (FIs), namely vapor-rich two-phase (LV-type), liquid-rich two-phase (VL-type), and daughter mineral-bearing three-phase (SL-type), are distinguished. Stage I, II and III contain all types of FIs (LV-, VL-, and SL-type), with homogenization temperatures (Th) of 268–462°C, 230–382°C and 180–340°C and salinities of 3.4–52.3, 3.4–44.5 and 3.7–39.9 wt% NaCl eqv., respectively, whereas stage IV has only VL-type FIs, with Th = 152–232°C and salinity = 3.4–7.9 wt%. Fluid geochemical data show that the Lianhuashan ore fluids were of medium–high temperature (236–382 °C), high-salinity (31.5–44.5 wt%), and relatively oxidizing conditions, typical of a NaCl-H 2 O system. The microthermometric and H–O isotope data (δ18O H2O = − 9.0 to 6.1 ‰; δD = − 149.0 to − 99.0 ‰) indicate that the ore fluids were initially magmatic with later meteoric water incursion. The sulfide S (δ34S = − 2.9–3.8 ‰) and Pb (206Pb/204Pb = 17.954 − 18.492, 207Pb/204Pb = 15.427 − 15.739, 208Pb/ 204Pb = 37.815 − 38.357) isotopes support that the metals were magmatic-derived. Fluid boiling, cooling, and meteoric water mixing were likely the main ore precipitation mechanism at Lianhuashan. We suggest that Cu minerals at Lianhuashan were precipitated with boiling at ∼ 1 km depth. For the ore-forming granodiorite porphyry (zircon U-Pb age: 252.8 ± 1.8 Ma), geochemical data indicate that the primary magma was formed by partial melting of the thickened or delaminated lower crust. Integrating the available age, geological, and geochemical evidence, we suggest that mineralization at Lianhuashan is spatial–temporal and genetically associated with the granodiorite porphyry, and was formed in a volcanic arc setting after the Paleo-Asian Ocean closure. [ABSTRACT FROM AUTHOR]

[Display omitted] • The system features diverse styles of REE mineralisation across and within different stratigraphic levels and host rocks. • The mineralogy and textures reflect a protracted evolution with multiple stages of REE-mineral formation and modifications. • Metamorphic remobilisation of REE-bearing minerals and sulphides during the Svecokarelian orogeny is highlighted. • The synthesis reviews key mineral system components and highlights mappable proxies for mineral prospectivity mapping. Rare earth elements (REE) have gained increasing significance for numerous technologies, particularly in today's rapidly expanding "green transition" applications such as wind generators and electric vehicle traction engines. Among the more well-known REE mineralisation types in Sweden, together with alkaline intrusions and apatite-iron oxide ores, is the classic yet enigmatic REE-Fe-polymetallic mineral system of Bastnäs-type. The mineralisation type is regional in context and occurs in a discontinuous SW–NE-striking belt (the REE-line) in the west-central part of the Palaeoproterozoic Bergslagen ore province, Sweden. This contribution is aimed at integrating and synthesising existing geological, mineralogical, and textural features with new observations from both well-known and several lesser-known, underexplored or previously unrecognised REE-enriched occurrences within this belt, and to discuss key features within the context of mineral systems modelling. A considerable diversity in both the style and abundance of REE mineralisation as well as in discrete REE mineralogy is evident both regionally across the entire REE-line and locally within different ore districts or mine fields. These variations also extend laterally within or across different stratigraphic levels, and within different host rocks, primarily skarn-altered metacarbonates but also variably altered felsic metavolcanic rocks. Many of the mineralisations share similar textural features, which record a protracted evolution with multiple stages of formation or replacement of REE-minerals. The earliest recognised REE assemblages feature fine-grained cerite-(CeCa) with minor bastnäsite-(Ce) – bastnäsite-(La) or fluorbritholite-(Ce) – fluorbritholite-(Y) or locally britholite-(Ce) – britholite-(Y) minerals. Such assemblages typically display anhedral-granoblastic textures appearing in folded assemblages, all suggesting recrystallisation and ductile deformation during regional metamorphism of REE-minerals that had formed during an early stage of the Svecokarelian orogeny. Overprinting overgrowths and cross-cutting vein-like features of allanite-group minerals likely represent different stage(s) of REE mineralisation and (re)-mobilisation during this orogenic evolution. Several of the REE-enriched occurrences contain variably abundant and diverse polymetallic Cu-Mo-Bi-(Co) sulphide mineralisation that typically occur in late paragenetic positions and show a prevalence to REE-rich assemblages, often dominated by different allanite-group minerals. Sulphide and REE mineralisation are locally strongly associated with metamorphic minerals formed during metamorphism of variably Mg-(Fe)-altered metavolcanic rocks. The diversity in style and intensity of the REE mineralisations, along with variations in textures and specific mineralogy, suggest slight differences in the ore-forming conditions or environment at the time of mineralisation. Additionally, these differences may also reflect variations in the preservation or modification processes that operated later in the evolution of the Svecokarelian orogeny, also featuring remobilisation of REEs and sulphidic minerals. The insights gained from all available evidence synthesised herein, from micro-scale to province-scale, help define key proxies for prospectivity mapping. The combined evidence supports that the primary ore-forming stages in the mineral system coincided with felsic volcanism and associated sub-volcanic to plutonic processes at around 1.9 Ga. [ABSTRACT FROM AUTHOR]

In both the diopside-magnetite stage (Stage I) and phlogopite-magnetite stage (Stage II), the cobalt mainly occurs in magnetite, and its content gradually decreases from 80 to 30 ppm as the system evolved. During the sulfide stage, minor pyrite deposited near the intrusion, and cobalt occurs in the pyrite lattice and also forms numerous independent cobalt minerals. Pyrite is abundant in the distal part of the ore-body, where all cobalt occurs in pyrite, and independent cobalt minerals are absent. [Display omitted] • The occurrence status of cobalt minerals in different types of ores at Longqiao Iron deposit has been investigated. • The metallogenic model of cobalt at Longqiao Iron deposit has been established. • New insights and methods have been provided for the study of cobalt associated with similar skarn-type iron deposits in eastern China. Longqiao is a cobalt-rich skarn iron deposit in Eastern China. As a typical representative of its type, it provides an opportunity to study the occurrence, distribution, and factors controlling cobalt in these deposits. Cobalt-bearing ores in Longqiao deposit can be classified into two types: cobalt-bearing diopside-magnetite ore (Co-Di-Mag) and cobalt-bearing phlogopite-magnetite ore (Co-Phl-Mag). Systematic whole-rock geochemical analysis, automated mineral analysis (TESCAN Integrated Mineral Analyzer, TIMA), and LA-ICP-MS trace element analysis were conducted on the two ore types. Three independent cobalt minerals（cobaltite, glaucodot, and carrollite）were found in Co-Di-Mag; no independent cobalt minerals were found in Co-Phl-Mag. TIMA and LA-ICP-MS analyses showed that cobalt in Co-Phl-Mag is mainly hosted in pyrite, so the pyrite content has a decisive role in the overall cobalt content. Cobalt in Co-Di-Mag is controlled by the content of magnetite, pyrite, and cobalt minerals. In both the diopside-magnetite stage (Stage I) and phlogopite-magnetite stage (Stage II), the cobalt mainly occurs in magnetite, and its content gradually decreases from 80 to 30 ppm as the system evolved. During the sulfide stage, minor pyrite deposited near the intrusion, and cobalt occurs in the pyrite lattice and also forms numerous independent cobalt minerals. Pyrite is abundant in the distal part of the ore-body, where all cobalt occurs in pyrite, and independent cobalt minerals are absent. Cobalt mainly occurs in pyrite in Longqiao deposit, which is favorable for beneficiation and recovery. Similar skarn iron deposits are widespread in eastern China, and the cobalt in these deposits has potential for recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Las Herrerías deposit consists of a copper-rich mineralization dated at ca. 333–330 Ma that replaces an Early-Middle Cambrian ironstone formed in a third order oxic basin related to the Cambrian rifting event in SW Iberia. • The copper mineralization seems to be related with E-W tensional structures that focused hydrothermal fluids probably derived from distal peraluminous granite dated at ca. 332 Ma. Sr-Nd isotope geochemistry suggests that fluids are of crustal derivation. • Numerical modeling shows that ironstone is an excellent trap for Cu mineralization due to the control that it exerts of the pH and redox conditions of fluids at intermediate to low fluid/rock ratios. However, the precipitation of copper sulfides needs an extra source of sulfur that cannot be transported by the same hydrothermal fluid. • At Las Herrerías, the most likely source of the reduced sulfur is the thermogenic reduction of barite present in the ironstone. The amount of reduced sulfur is perhaps the major control to the grade and size of the mineralization. The central Ossa Morena Zone (SW Iberia) hosts a regionally extensive ironstone level interbedded with bimodal volcanic rocks, limestone and shale of Lower-Middle Cambrian age. The stratabound ironstone includes dominant magnetite and hematite with locally abundant chert and barite. It is interpreted as being (sub-)exhalative at or near the seafloor and formed during a rifting event that postdated the Cadomian orogeny. In some places, such as in the Las Herrerías deposit, the ironstone is irregularly replaced by a chalcopyrite-rich ore; the Cu-rich mineralization is accompanied by the pervasive phyllic alteration of the hosting siliciclastic sediments. The highest copper grades are found when the ironstone is crosscut by WNW-ESE-trending late-Variscan extensional brittle-ductile structures that are interpreted as the feeder channels for deep hydrothermal fluids. A similar nearby copper-rich mineralization (Pallares) is likely controlled by the tectonic contact between limestone and pyrite-rich black shale. Sr-Nd whole-rock isotope geochemistry data suggests that the Sr in the ironstone (87Sr/86Sr i ≈ 0.7088) is close to isotopic equilibrium with the local exhalative barite (0.7084–0.7086) and Cambrian seawater. The ironstone has a significantly more crustal εNd initial signature (<-1.8) than the coeval volcanic rocks (+5.2 to + 7.9). The younger sulfide mineralization inherited the Nd isotope composition of the ironstone but shows a significant enrichment in 87Sr (87Sr/86Sr > 0.7091) that is interpreted as related with the input of genetically different and more crustally-derived hydrothermal fluids. 39Ar-40Ar dating of the phyllic alteration suggest that the copper mineralization was formed at ca. 332–330 My. These ages are coeval with those of small peraluminous granite intrusions that host Cu-Au vein-like mineralization and dated at 331.8 ± 1.6 Ma (LA ICPMS U-Pb zircon). Our interpretation is that the copper-rich mineralization at the Las Herrerías area is the distal expression of an intrusion-related hydrothermal system. Numerical modelling shows that ironstone is an effective trap for copper precipitation due to the large changes in pH and f O 2 that take place when copper-bearing acid and reduced fluids react with the brittle ironstone. The precipitation of chalcopyrite, however, is controlled by the amount of available reduced sulfur in the ore trap. The δ34S values of the sulfides (+12.6 to + 21.6 ‰) suggest that the most likely source for the reduced sulfur is the thermogenic reduction of aqueous sulfate equilibrated with the exhalative barite (δ34S, +31.4 to + 35 ‰) with some minor input of reduced sulfur leached from the metasediments. This system could be considered as a variant of the IOCG clan. The formation of the ironstone and the copper mineralization, however, are separated by more than 200 My. Probably, many IOCG systems have a similar origin as Las Herrerías, with an ironstone being just a passive geochemical trap for the copper–gold mineralization. [ABSTRACT FROM AUTHOR]

• The cobalt mineralization was dated to ∼2100 Ma based on Re-Os isochron ages of cobalt-bearing pyrites. • Cobalt was mainly hosted in carrollite, linnaeite, and pyrite. • The Songjiashan deposit belongs to the sedimentary, metamorphic, and hydrothermal superposition type Co-Fe deposit. The Songjiashan Co-Fe deposit in the central part of the "Tongshan skylight" on the southeastern edge of the Zhongtiao Mountains is hosted by the volcanic-sedimentary rock series of the Paleoproterozoic Songjiashan Group. The spatial distribution of the orebodies is controlled by south-north trending rock units. Based on microscopic observations, the dominant ore minerals included magnetite, pyrite, chalcopyrite, carrollite, and linnaeite, while gangue minerals comprised quartz, calcite, sericite, and chlorite. Cobalt-iron ores had massive, banded, disseminated, and veinlet texture, and alteration of the host rocks included silicification, sericitization, pyritization, carbonation, and chloritization. Mineralization processes of the Songjiashan deposit were grouped into three periods: sedimentation, metamorphism, and hydrothermal. The Co concentrations in hydrothermal pyrite (Py-III) varied from 1.05 % to 3.75 %, with an average of 2.45 %. Cobalt in pyrite was homogeneously distributed and inversely correlated to Fe, indicating that Co isomorphically replaced Fe in pyrite. The characteristic Co/Ni ratio of pyrite varied greatly, ranging from 0.1 to 1000, reflecting various genetic types of sedimentation, metamorphism, and hydrothermal mineralization, with the main mineralization period primarily related to hydrothermal activities. Zircon U-Pb geochronology of the host rock and Re-Os isochron of Co-bearing pyrites indicate that Co mineralization mainly occurred at ∼2100 Ma. In-situ S isotopic analysis of sulfides reveals two peak δ34S values of 5–9 ‰ and 12–16 ‰. We interpret that the former value reflects the mixing of volcanic and marine sulfate sources, while the latter value is mainly artributted to marine sulfate sources. All δ34S values were lower than those of Proterozoic marine sulfates (15–20 ‰). Accordingly, we infer that thermochemical sulfate reduction plays a key role in marine sulfate reduction, and that the formation of Co-rich ore bodies in the Songjiashan deposit have undergone processes of initial sedimentation, metamorphism-deformation, and subsequent hydrothermal overprinting. Genetically, we suggest that the Songjiashan deposit belongs to a sedimentary-metamorphic hydrothermal superposition type Co-Fe deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The LFC deposit belongs to the skarn-type polymetallic sulfide deposit. • A Comparative Study of the LFC Deposit and "Makeng-Type" Deposit Has Been Conducted. • Emphasizing the significance of disconformity between the Jinshe and Lindi Formations within the window areas of the thrust-nappe structure system in large iron deposit exploration. The Southwest Fujian Depression Belt is a prominent metallogenic zone for skarn-type iron polymetallic deposits in China, with the Longfengchang (LFC) sulfur polymetallic deposit representing a medium-scale, sulfide-dominated deposit in this region. This study conducted a detailed analysis of the LFC deposit, focusing on its mineralogy, mineral composition, and in-situ sulfur isotopes, alongside a comparative study with the "Makeng-type" deposit. The study aims to elucidate the genesis of the LFC deposit, its relationship with the "Makeng-type" deposit, and the factors underlying differences in dominant economic minerals and resource scale. The LFC deposit is hosted within the skarn above the fault contact zone between the Lindi Formation sandstone and the Chuanshan–Qixia Formation carbonate, with mineralization stages classified as skarn-magnetite, quartz-sulfide, and carbonate. LFC garnets are primarily composed of CaO, TFeO, and SiO 2 , with minor Al 2 O 3 and trace amounts of MgO and MnO, classifying them as distal exoskarn andradite. The presence of Mn3+ substituting for Fe3+ in garnet suggests that the ore-forming fluid during the garnet skarn stage was likely oxidizing and weakly acidic. LFC pyrites exhibit Co/Ni ratios primarily ranging from 1 to 10, decreasing from Py 1 to Py 3. In-situ sulfur isotope δ34S values range from −1.48 to 3.51 ‰, centering around 0 ‰, and increase from Py 1 to Py 3 , suggesting a magmatic-hydrothermal origin and a cooling metallogenic process. Thus, the LFC deposit is classified as a magmatic-hydrothermal skarn-type deposit, consistent with the genesis of "Makeng-type" deposits. The absence of the Jinshe Formation, and mantle-derived magma contribution, and less developed "Si-Ca" interface may explain the smaller scale and different mineralization type in the LFC deposit compared to the "Makeng-type" deposit. The key prospecting area for large iron-sulfur polymetallic deposits in the Southwest Fujian Depression Belt should feature a nappe structural window, well-preserved Jinshe Formation, developed "Si-Ca" interface, Yanshanian high-K calc-alkaline to shoshonitic intrusions, and coeval mantle-derived magma. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cobaltite was discovered within pyrite at the De'erni deposit for the first time. • The lattice defects provided sites for the nucleation of cobaltite within pyrite. • Cobaltite NPs contributed to the uneven distribution of Co in pyrite. Cobalt (Co) is a critical metal that occurs in many types of deposits, Co minerals and sulfide hosts are the main forms of Co occurrence. Pyrite is the most important cobalt-bearing mineral in the De'erni Cu-Zn-Co ultramafic-hosted volcanogenic massive sulfide deposits. However, the occurrence and enrichment of Co in pyrite remain unclear. In this study, a combination of LA-ICP-MS and STEM techniques was employed to conduct a detailed mineralogical investigation of pyrite in the De'erni deposit. The results revealed significant variations in cobalt content among pyrite samples from different mineral assemblages. Pyrite associated with magnetite (Mag), pyrrhotite (Po), chalcopyrite (Ccp), arsenopyrite (Apy), and bornite (Bn) (Py-Mag-Po-Ccp-Apy-Bn suite of mineral assemblages) exhibited the highest cobalt content, which ranged from 672.6 ppm to 2007 ppm. Cobalt occurs in two forms in the pyrite from the De'erni deposit: as cobaltite nanoparticles (NPs) and as a substitute for iron (Fe) in the pyrite lattice. The enrichment mechanism of cobalt in pyrite was explored at the deposit and mineral scales. The results indicate that a decrease in ore-forming fluid temperature and an increase in cobalt content may be significant factors contributing to cobalt enrichment at the deposit scale. Lattice defects may play a crucial role in cobalt enrichment within the pyrite lattice. Furthermore, the discovery of cobaltite NPs in pyrite could provide new insights for explaining the complex zonation of the cobalt element in pyrite. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ore-bearing rhyolite in the Ulaan deposit is an A-type rhyolite formed in the early Late Jurassic. • The mineralization of the Ulaan deposit was formed during the late Late Jurassic, contemporaneous with quartz porphyries in the deposit. • The ore-forming materials in the Ulaan deposit were derived from magmatic-hydrothermal fluids. The Ulaan silver-lead–zinc deposit (hereinafter referred to as the Ulaan deposit) is identified as the largest silver-lead–zinc polymetallic deposit in Mongolia, with proved reserves including 2,240 tons of silver (Ag; average grade: 49 g/t), 440,000 tons of lead (Pb; average grade: 1.13 %), and 810,000 tons of zinc (Zn; average grade: 2.07 %). However, the genesis of this deposit remains unclear. The Ag-Pb-Zn ore bodies in the deposit, occurring as cylinders in shape within the Middle-Late Jurassic rhyolites, are governed by a concealed breccia pipe. The ore minerals include galena, sphalerite, and pyrite, followed by chalcopyrite, hematite, stibnite, and siderite. The primary alterations of the surrounding rocks include silicification, chloritization, kaolinization, argillization, carbonatization, and skarnization. The Rb-Sr dating of sulfide minerals and associated vein minerals in the ores yielded isochron ages varying in a range of 146 ± 3 Ma (n = 6, MSWD=1.3), suggesting mineralization during the Late Jurassic. The δ34S values of sulfide minerals in the ores range from 1.6 ‰ to 4.3 ‰, suggesting that the sulfur originated primarily from magmas or deep sources. The isotopic compositions of coexisting sphalerite-galena minerals in the deposit revealed mineralization temperature estimates ranging between 331 °C and 449 °C, indicating a medium- to high-temperature ore-forming conditions. The sulfide minerals exhibit 208Pb/204Pb ratios ranging from 38.138 to 38.301, 207Pb/204Pb ratios from 15.543 to 15.594, and 206Pb/204Pb ratios from 18.318 to 18.354, suggesting that ore-forming metals, represented by Pb, also originated primarily from mantle source. The zircon U-Pb dating of rhyolites in the ore-hosting strata and ore-controlling breccia pipes yielded ages of 160.6 ± 1.7 Ma (n = 24, MSWD=0.68) and 161.6 ± 1.6 Ma (n = 30, MSWD=0.89), respectively, indicating volcanic eruptions during the early Late Jurassic. These ore-hosting rhyolites exhibit characteristics of A-type rhyolites, suggesting that they were formed in an intracontinental extensional environment. These rhyolites share similar rare earth element (REE) distribution patterns with fluorite formed in the main mineralization stage, suggesting a genetic link between the mineralization and magmatic processes. This study proposes that the Ulaan deposit was a hydrothermal deposit formed in an extensional environment following the closure of the Mongol-Okhotsk Ocean, with ore-forming metals and hydrothermal fluids associated with volcanic rocks or magmatic-hydrothermal processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Forecast vent field exhibits substantial gold concentrations, reaching up to 101 ppm. • Electrum is the primary form of gold-rich mineralization. • The majority of sulfur and metals in hydrothermal fluids are sourced from magmatic volatile influxes. • The combination of magmatic fluid–seawater mixing and host rock alteration produces the gold-enriched massive sulfides. Massive sulfides and sulfide-bearing breccia were collected from the Forecast vent field in the southern Mariana Trough. These samples exhibit varying degrees of hydrothermal alteration and/or mineralization, with the former type having significant enrichments in Au (up to 101 ppm). In this study, detailed analyses of mineralogy, geochemistry, S isotope, and fluid inclusion were conducted to understand the unusual Au-rich mineralization. Mineralogical investigations and geochemical analyses (LA–ICP–MS and EPMA) of dominant sulfide minerals indicate that electrums, the main phase of Au mineralization, are characterized by two different generations based on mineralogical relationships and fineness. Early-stage high fineness electrums (930–981 ‰) are associated with sphalerite under relatively high-temperature fluid conditions, whereas galena is main host mineral related to late-stage low fineness electrums (773–868 ‰). Sphalerite geothermometry (231–264 °C), the occurrence of colloform textured sulfides, and microthermometric characteristics of fluid inclusions (T h = 220–304 °C; Salinity = 1.4–6.6 wt% NaCl equivalent; a general trend of decreasing salinity with decreasing T h) indicate that significant decreases in H 2 S activity, attributed to seawater dilution and rapid precipitation of sulfide minerals, facilitated the efficient destabilization and deposition of Au transported as sulfide complexes from hydrothermal fluids. In particular, the lower 34S values (+0.2 ‰ to + 1.3 ‰) of sulfides compared to those of arc/back-arc lavas (δ34S = +5‰ to + 11 ‰), along with the prevalence of CO 2 in the vapor phase of fluid inclusions, reflect that the significant contribution of magmatic volatile influx supplied most of the sulfur and metals (including Au) to the Forecast hydrothermal fluids. Additionally, the abundance of montmorillonite and varying proportions of sulfide and gangue minerals observed in hydrothermal samples suggest that the chemical buffering of fluids by associated substrates and/or sediments could be another significant factor in promoting Au-rich mineralization. Therefore we conclude that the combination of magmatic fluid–seawater mixing and host rock alteration plays an important role in the formation of Au-enriched massive sulfides in the Forecast vent field. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ analyses on sulfides help in discriminating the Yongping metallogeny. • The sphalerite and pyrite chemistry from the Yongping area resembles a skarn system. • A narrow range of δ34S V-CDT values from Yongping sulfide suggests a magmatic source. • Jurassic Yanshanian magmatism (Shizitou granitoids) is the primary source of metal enrichment. • Yongping skarn was likely formed at medium–high temperature, magmatic-hydrothermal fluid. Yongping copper deposit is a large-scale polymetallic mine that contains 1.6 Mt of proven Cu metal reserves with an average grade of 0.74 % and contributes significantly to China's production of copper. This deposit is situated in the eastern part of the Qin-Hang Metallogenic Belt (Jiangxi province, SE China) at the contact zone between the Yangtze Cu–Mo metallogenic belt and the Jiangxi W–Sn–REE metallogenic belt. The thick stratiform and lenticular-shaped orebodies are hosted in the Carboniferous Yejiawan Formation, consisting of sandstone, limestone, mudstone, and chert-rich clastic rocks. Dominant metal-bearing minerals are chalcopyrite and pyrite with a minor amount of sphalerite, tetrahedrite, galena, molybdenite, pyrrhotite, magnetite, hematite, and scheelite. Although intensive research has been done on its geological setting, geochemical characteristics, and geodynamic evolution over the past thirty years, the origin and depositional environments have remained controversial. In the current research, in situ trace element geochemistry and sulfur isotope analyses, coupled with microscopic investigation, were conducted on sulfide minerals using the LA-ICP-MS technique. The results display that Yongping pyrite rich in Co, As, Ni, Zn, Cu, and Te and deplete in other trace elements. Sphalerite rich in Fe, Mn, Cu, and Cd, followed by In, Co and Ga. The calculation results of formula T(°C) = (Fe/Zn + 0.2953)/(0.0013) reveal that sphalerite was formed in medium–high temperature conditions (262 °C–377 °C). The δ34S V-CDT values of studied sulfides (pyrite, chalcopyrite, sphalerite, and tetrahedrite) varied from −1.52 ‰ to 5.13 ‰ with an average of 2.36 ‰, which are highly consistent with those recorded from porphyritic biotite granite stock of Shizitou (from 2.20 ‰ to 4.5 ‰), suggesting a dominantly magmatic origin. Collectively, trace element compositions of analyzed sphalerite and pyrite from the Yongping area exhibit characteristics of typical skarn deposits. Combined with previous studies, we can conclude that the Yongping Cu deposit is a skarn deposit that was most likely formed by contact metasomatism after the intrusion of the Jurassic Huoshaogang-Shizitou granitic stock into the Carboniferous Yejiawan Formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co is mainly concentrated in violarite, pentlandite and pyrite, and substitutes isomorphically for Fe and Ni. • Lherzolites have heavier δ56Fe pn-ccp than olivine websterites, suggesting different stage of magma. • δ34S increase from pyrrhotite, pentlandite, chalcopyrite to pyrite, implying external S contributed to its sulfide saturation. • Co contents vary with δ56Fe and δ34S, indicating that sulfide segregation was critical to Co enrichment. The Zhubu Ni–Co–PGE sulfide deposit in the Permian Emeishan Large Igneous Province (LIP), SW China is hosted by a mafic–ultramafic intrusion that comprises two morphologically distinct ore-forming spaces: a central, layered sequence that represents a magma chamber surrounded by a marginal sub-vertical conduit zone. The marginal conduit zone contains significant Ni–Co–PGE sulfide mineralization, suggesting that high volumes of sulfide-bearing silicate melt flowed through the magma conduit system. Determining the hosts of Co is key to understanding the Co enrichment process in the Zhubu deposit, as well as in the Emeishan LIP as a whole. We assess this here using the geochemistry and Fe–S isotope compositions of sulfides in the Zhubu deposit. Cobalt is mainly concentrated in pentlandite sulfide in the websterite, with Co contents increasing in the order pyrrhotite < chalcopyrite < pyrite < pentlandite < violarite; the abundance of violarite, however, is notably lower than that of the other sulfides. The Co contents of pentlandite, pyrite, and chalcopyrite are negatively correlated with their Ni and Fe contents, suggesting that Co substitutes isomorphically for Ni and Fe in the sulfide structure. The δ56Fe values of sulfides increase in the order pyrrhotite < chalcopyrite < pentlandite < pyrite resulted from kinetic fractionation of Fe isotopes. The δ56Fe values of pentlandite and chalcopyrite in lherzolite are higher than those in websterite, implying that lherzolite and websterite formed in compositionally distinct magmas, Fe isotope compositions become heavier with crystal fractionation. The δ34S values of sulfides increase in the order pyrrhotite < pentlandite < chalcopyrite < pyrite, similar to the fractionation sequence of sulfide melts, suggesting that externally derived S was added to the magma and contributed to its sulfide saturation. The Co contents of chalcopyrite and pyrite vary positively with δ56Fe values, and negatively with δ34S values, indicating that the addition of externally derived S and resulting sulfide segregation were critical to Co enrichment. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ Cu isotope data show large fractionation between Sn-rich and Cu-rich ores. • Cu isotopes and modeling show water–rock interaction crucial in Sn-Cu mineralization. • Cu source of the Sn-Cu coexisting deposit may be the Cu-rich country rocks. This study presents high-resolution in situ Cu isotope data for chalcopyrite from the Jinkeng Sn-Cu deposit, Guangdong Province, China, with the aim of understanding how the Sn-Cu mineralization was formed. Results show that early chalcopyrite (quartz-cassiterite stage) has the lowest δ65Cu values (–0.01 to +0.02 ‰), similar to δ65Cu values (∼0‰) in most granites. In contrast, chalcopyrite from the subsequent cassiterite-sulfide stage exhibits the highest δ65Cu values (+0.90 to +0.97 ‰), comparable to those of the volcanic country rocks (+0.87 to +1.00 ‰). δ65Cu values in late chalcopyrite gradually decrease (from +0.79 to +0.45 ‰) across the latest ore-forming stages, from quartz-sulfide to quartz-calcite-sulfide mineral assemblages. Observed variation in δ65Cu is explained by water–rock interaction. Quantitative geochemical modeling also demonstrates that the Cu isotopic compositions of chalcopyrite record variable degrees of water/rock ratios during water–rock interactions. Therefore, our results suggest that water–rock interaction plays a critical role in providing Cu for Sn-Cu ore systems. The study further indicates that in situ Cu isotope analysis provides an accurate and efficient tool for diagnosis of magmatic-hydrothermal processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co and Ni occur mainly in sulfides through isomorphic substitution in the Yindongshan ultramafic–mafic intrusions. • Magmatic iron deposits hosted by ultramafic–mafic intrusions with sulfide mineralization are promising targets for Co and Ni exploration. The Yindongshan iron deposit in western Hubei Province of China is hosted within Ordovician ultramafic–mafic intrusions. Recent field geological surveys have detected cobalt (Co) and nickel (Ni) enrichment within the Yindongshan clinopyroxenite, suggesting good potential for subeconomic Co-Ni mineralization. This study investigated the occurrence modes and enrichment processes of Co and Ni in the Yindongshan deposit through field geology and in situ analysis of the rock texture, geochronology, and geochemistry of sulfides, Fe-Ti oxides, and silicate minerals. The Yindongshan clinopyroxenites were emplaced at 440.2 ± 7.2 Ma via titanite LA-ICP-MS U-Pb dating, and underwent extensive post-magmatic metamorphism at 401.2 ± 8.6 Ma via apatite U-Pb dating. This metamorphism led to the widespread formation of amphibole via the replacement of clinopyroxene. Subsequently, hydrothermal epidote-albite veins, calcite-pyrite veins, and later actinolite veins developed. Pyrites from both clinopyroxenites and calcite veins show limited δ34S variations from −5.4 ‰ to −1.2 ‰, suggesting a magmatic sulfur source. Late-vein actinolites display geochemical characteristics distinct from those of amphiboles, indicating possible involvement of external fluids. LA–ICP–MS trace element results reveal a general increase in Co and Ni contents from silicate minerals and Fe-Ti oxides to pyrite and from earlier-crystallized coarse-grained clinopyroxenite to later medium- to fine-grained clinopyroxenite. The highest Co and Ni contents observed in pyrite from coarse-grained clinopyroxenite suggest their preferential incorporation into early sulfide minerals and then progressively depleted through magmatic evolution such as fractional crystallization. The positive correlation between Co and Ni with Fe in pyrite, along with the consistent parallel time-resolved LA–ICP–MS depth profiles among different mineral phases, indicates that isomorphic substitution occurred in pyrite. In silicate minerals, the Co and Ni contents increase from pyroxene, amphibole, to actinolite, with almost no Co or Ni present in epidote. The elevated Co and Ni contents in metamorphic amphiboles are attributed to their remobilization from magmatic pyrite to newly formed amphiboles. During the late hydrothermal phase, external fluids might transport additional Co and Ni, contributing to higher concentrations in late actinolite veins. In general, Co and Ni in the Yindongshan iron deposit are primarily hosted in sulfide minerals and can be remobilized during regional metamorphism and metasomatism. Thus, magmatic iron or iron–titanium oxide deposits hosted by mafic–ultramafic intrusions with sulfide mineralization may serve as promising targets for further Co-Ni exploration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Niukutou Pb–Zn-(Fe) deposit is a Co-rich skarn deposit in the East Kunlun metallogenic belt. • Two independent cobalt minerals, cobaltite and glaucodot, are present in this deposit. • Cobalt precipitates during the late Fe-Cu sulfide stage. • Co enrichments are related to decreases in temperature and f O 2 in magmatic-hydrothermal dominant stages. The East Kunlun orogenic belt is one of the most important Co-rich polymetallic metallogenic belts in China. Niukutou, a typical Pb-Zn-(Fe) skarn deposit, is situated within the marble formations of the Ordovician-Silurian Qimantagh Group in this belt. Six distinct stages of mineralization have been identified: (1) prograde skarn stage, (2) hydrous mineral-oxide stage, (3) pyrrhotite stage, (4) chalcopyrite stage, (5) sphalerite-galena stage, and (6) carbonate stage. Co enrichment predominantly manifests at chalcopyrite stage, with two distinct Co minerals identified: glaucodot and cobaltite. Co is also present as isomorphous substitution in sulfides (mostly arsenopyrite) and as inclusions in chalcopyrite. Variations in As and S contents in arsenopyrite suggest a steady decrease in ore-forming fluid temperature from the pyrrhotite stage to sphalerite-galena stage. Variations in the Co, Ni, Se, As, Sb, Cu, Sn, Ag, and Zn contents in pyrite indicate fluctuations in temperature, oxygen fugacity, and fluid composition during ore formation. Sulfur isotope compositions (δ34S) through the pyrrhotite stage to the sphalerite-galena stages show a limited range from +3.4 to +7.0 ‰, suggesting a predominantly magmatic source. Whereas, the δ34S of pyrite and marcasite in carbonate stage exhibit significant variations from −22.5 to +22.7 ‰. We propose that this significant variation may be caused by mixing of sulfur from the surrounding rocks and the large fluctuations in oxygen fugacity due to the influx of meteoric water at the carbonate stage. Overall, Co in Pb-Zn skarn system may occur either as independent minerals or as lattice substitution in sulfides such as arsenopyrite. The deposition of Co-bearing minerals is related to decreases in temperature and f O 2 during the chalcopyrite stage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sulfides are main hosts of Co and Ni in the Panzhihua intrusion. • Three types of Co occurrence patterns are identified. • Co enrichment are mainly controlled by sulfide segregation and crystallization. The Panzhihua deposit is the one of the largest Fe-Ti oxide deposits in the world and holds 10,000 to 20,000 tons of Co resource with grades varying from 0.01 % to 0.02 %. Detailed field geological investigations and major and trace element analyses, were conducted to reveal occurrence of Co and Ni and their enrichment mechanism. Co and Ni are predominantly enriched in massive magnetite ores (average 277 ppm Co, 281 ppm Ni) of the Lower zone in the Panzhihua intrusion. Co occurs as three types:(1) independent minerals such as cobalt pentlandite (Co 3.96-6.98 Ni 0.85-2.62 Fe 1.36-2.53 S 8) and linnaeite (Co 1.65-1.88 Ni 0.99-1.05 Fe 0.15-0.37 S 4); (2) isomorphic state substituting for Fe, Ni and/or Mg in pentlandite (Co 0.53-0.55 Ni 4.57-4.65 Fe 3.80-3.83 S 8), Co-bearing pyrite (Co 0.09-0.12 Fe 0.89-0.93 S 2), pyrrhotite (Co 111–1964 ppm), olivine (Co 161–184 ppm), pyrite (Co 3–272 ppm), titanomagnetite (Co 57–181 ppm), ilmenite (Co 57–110 ppm), clinopyroxeneclinopyroxene (Co 34–40 ppm); (3) microscopic sulfide inclusions in chalcopyrite. Sulfide segregation and crystallization are principal mechanisms of Co enrichment. The results offers valuable insights into understanding Co mineralization, resource assessment, and comprehensive utilization in magmatic Fe-Ti oxide deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three Co mineralization stages in the Tuolugou deposit are identified. • Mineral chemistry and nanoscale textural study of the Co pyrite were investigated. • Co mineralization here is related to SEDEX genesis. The Tuolugou sedimentary-exhalative (SEDEX) Co-Au deposit is located in the eastern Kunlun metallogenic belt of the northern Qinghai-Tibet Plateau in China. Pyrite is the prevalent Co-hosting sulfide mineral that occurs in the Tuolugou deposit. In this study, we investigated mineral characteristics of Co-bearing pyrite and effect of Co on crystal structure of the pyrite to obtain a better understanding of Co mineralization. Three pyrite generations were identified, including Co-barren pyrite (Py-1, formed during the early mineralization stage I, with Co content of 1-3844 ppm), Co-rich pyrite (Py-2, formed during the sedimentary-exhalative stage II, Co content 15–36522 ppm), and Co-rich pyrite (Py-3, formed during metamorphic stage III, with Co contents of 448–10505 ppm in Py-3A, and 1371–14904 ppm in Py-3B). As Co enters the pyrite structure, it is discovered that the octahedrons in pyrite is twisted and tilted, the lattice parameters (a 0) rise, and the sulfur atom positions alter. The Co-rich Py-2 shows a similar REE and trace element distribution as those in quartz albitite, which indicates that Co mineralization is related to SEDEX genesis. Subsequent metamorphism resulted in additional Co enrichment. This detailed study of Co-bearing pyrite provides insights on the details of isomorphism Co in pyrite similar to the situation of this deposit as medium–low Co grade. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simultaneous thrust faults, post-collisional porphyries and gold mineralization. • Decreasing sulfur fugacities, oxygen fugacities and temperatures during mineralization. • Gold mineralization genetically related to post-collisional porphyries. The relationships among magmatism, orogeny, and gold mineralization in lode gold deposits have been controversial for a long time. The East Kunlun Orogen in northern Tibet has experienced a complex Paleo-Tethyan tectono-magmatic evolution and hosts the largest Wulonggou lode gold deposits (>120 t). The Shuizhadonggou-Huanglonggou (SZDG-HLG) gold deposit is the largest in the Wulonggou goldfield and is an excellent candidate for solving the controversy through detailed field observations, magmatic and hydrothermal mineral in-situ U-Pb dating, and gold-bearing sulfide in-situ trace elements and sulfur-lead isotopes. Gold mineralization in the SZDG-HLG deposit includes sulfide disseminations and minor amounts of small quartz-sulfide veins in hydrothermal alteration assemblages along a ductile shear zone. Gold mineralization can be divided into four stages based on crosscutting relationships and associated alteration assemblages. U-Pb ages from magmatic zircon, hydrothermal rutile, and hydrothermal monazite support field relationships that gold mineralization was later than the ductile deformation but synchronous with the post-collisional porphyries. Gold mineralization evolved from high to low temperatures (560℃ to less than 300℃), accompanied by markedly decreased sulfur fugacities (–6.3 to –12.5) and oxygen fugacities (–20.7 to –40.5). The gradual increase of sulfur isotopes (δ 34S) from stage 1 (–0.9 to 1.8 ‰ in Py1a) to stage 3 (up to 8 ‰) is ascribed to sulfide precipitation from a finite fluid reservoir, while the sharp decrease of δ 34S values in stage 4 (down to –24 ‰) is caused by the fluid oxidation. The negative covariations of δ 34S and Se/S values, positive correlations between Au and chalcophile elements (As, Sb, Te, and Bi) in most sulfides, and overlapping lead isotopes of sulfides and Late Triassic granodiorite-diorite confirm a post-collisional magmatic gold and sulfur source. This study demonstrates that lode gold deposits in Phanerozoic orogens having similar characteristics to their counterparts in Archean metamorphic terranes can be genetically related to post-collisional magmatism. [ABSTRACT FROM AUTHOR]

[Display omitted] • Limited crystallization of olivine and chromite promote sulfide mineralization in the Wuxing complex. • Silicate minerals in the Wuxing complex contain lower Co and Ni contents compared to typical Alaskan-type complexes due to sulfide segregation. • Long-term magmatism revealed by Re-Os isotopic ages contribute to the Ni-Cu-PGE mineralization in the Wuxing complex. Alaskan-type mafic–ultramafic complexes have been recognized as potential hosts of magmatic Ni-Cu sulfide deposits. However, the distribution and controlling factors of ore-forming metal elements like Co and Ni within these complexes remain poorly understood. This study offers comprehensive petrological observations and quantifies the Co and Ni contents of silicate minerals and sulfides in the Wuxing complex, the oldest Alaskan-type complex hosting a distinctive PGE-rich Ni-Cu sulfide deposit in the Central Asian Orogenic Belt. The Co-rich minerals, including cobaltite and pentlandite, occur as inclusions or interstitial grains in other mineral phases. Among the sulfide assemblages (pyrrhotite, pentlandite and chalcopyrite), pentlandite exhibits the highest 3.59 ∼ 5.98 wt.% of Co and 28.7 ∼ 32.7 wt.% of Ni contents, with the Co contents being 2 to 10 times higher than those in magmatic Ni-Cu sulfide deposits. Clinopyroxene and hornblende in the Wuxing complex display lower Co and Ni contents compared to those in sulfide-free rocks of typical Alaskan-type complexes. This could be ascribed to the reduction in Co and Ni contents in evolved magmas following sulfide segregation. Additionally, lack of olivine and chromite crystallization would elevate Co and Ni contents in silicate magma and promote the sulfide mineralization in the Wuxing complex. The Re-Os isotopic dating in ore samples at 596 Ma, combined with previously zircon U-Pb ages of 510 ∼ 517 Ma, reveals that long-term magmatism would facilitate mineralization in the Wuxing complex. Our investigations provide a new insight of mineral crystallization for understanding of magmatic Ni-Cu-PGE sulfide mineralization in Alaskan-type complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] The Bushveld Complex is the largest known layered intrusion in the world and has been extensively studied. However, there remains an absence of systematic investigations of cobalt (Co) and nickel (Ni) distribution at various scales. Elements Co and Ni behave varying degrees of compatibility within chromite, silicates, and sulfides, making them effective proxies for elucidating chemical competition and interaction among these minerals. This study aims to characterize Co and Ni distribution in olivine, pyroxenes, chromite, and whole rocks from different seams of the Bushveld Complex and to reveal their controlling factors. Our results indicate large variations of whole-rock Co and Ni concentrations, with a decreasing sequence of dunites (Co: 156–222 ppm; Ni: 2208–2750 ppm) > harzburgites (Co: 87.8–174 ppm; Ni: 152–2050 ppm) > pyroxenites (Co: 58.7–143 ppm; Ni: 387–1947 ppm) > norites (Co: 16.0–113 ppm; Ni: 153–646 ppm) > anorthosites (Co: 3.20–16.3 ppm; Ni: 19.7–97.2 ppm). In general, olivine has higher Ni contents (717–4496 ppm) and lower Co (105–239 ppm) than chromite (Ni: 524–1948 ppm; Co: 236–563 ppm). Pyroxenes have apparently low Co (orthopyroxene: 39.7–184 ppm; clinopyroxene: 17.2–114 ppm) and Ni contents (orthopyroxene: 224–1195 ppm; clinopyroxene: 177–831 ppm). Chromite in chromitites has lower Co content than that in other rocks. The whole-rock and mineral Co and Ni variations in the stratigraphic profile are closely related with lithology, mineral assemblages and element partition coefficients in minerals. The Co contents in the chromite and pyroxenes vary alternately with the chromitites and rock seams, with lower Co contents in ore samples than that in silicate rocks. Whole rocks and mineral separates in the Merensky Reef exhibit the highest Ni contents (whole-rock: up to 4000 ppm; orthopyroxene: 1035–1195 ppm; clinopyroxene: 730–831 ppm; chromite: 1760–1948 ppm), which are likely attributed to sulfide segregation and diffusion between sulfides and other minerals. In addition, the sulfide segregation may also be a main factor resulting in Co-Ni decoupling in pyroxenes from the Main Zone of the Bushveld Complex. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fo-Mn correlations in olivine can record in situ sulfide saturation event. • Orebody 1 in the Jinchuan deposit was formed by in situ sulfide saturation. • The in situ sulfide saturation initiated when the crystallizing olivine reached a Fo79.5 and ended at Fo84. • The magma conduit's geometric resemblance to a de Laval nozzle triggered the in situ saturation as magma flowed through it. When and how sulfide saturation occurred in the Jinchuan magmatic Ni-Cu sulfide deposit are poorly constrained. To address this issue, we investigated compositional variations and crystallization temperatures of olivine in various ores and rocks in orebody 1 of the Jinchuan deposit. The forsterite (Fo) values and Mn contents in olivine vary respectively from 79.6 to 85.2 and 1270 to 2463 ppm in net-textured ores, 76.7 to 84.2 and 1425 to 2865 ppm in patchy net textured ores, 78.7 to 84.1 and 1440 to 2649 ppm in disseminated ores, and 69.7 to 81.8 and 1495 to 3191 ppm in sulfide-barren lherzolites. The estimated crystallization temperatures of olivine in these ores/rocks range from 803 to 1163 ℃, 871 to 1314 ℃, 821 to 1507 ℃, and 929 to 1652 ℃, respectively. These data revealed two distinct groupings in both olivine Fo-Mn correlations and crystallization temperatures cluster splitting at a Fo of 79.5 and a temperature of 1100 ℃. The wider range of Mn content with a given Fo value higher than 79.5 compared to those with Fo values lower than 79.5 indicates the onset of in situ sulfide saturation at a Fo of 79.5. The termination of sulfide saturation is epitomized by olivine in disseminated ores with a peak Fo content of 84. The abrupt temperature drops from ca. 1400–1500 °C to ca. 800–1100 °C in the parental magma likely occurred when the magma flowed through the westernmost portion of this segment, which resembles a de Laval nozzle. This geometry could have induced rapid cooling and decompression of the magma, consequently promoting degassing through decompression. These reductions in temperature and H 2 O content of the magma would collectively result in a decrease in the sulfur concentration at sulfide saturation (SCSS), which would exceed any SCSS increase due to decompression. Our findings emphasize the critical role of magma conduit geometry in physicochemical changes of the parental magma for sulfide saturation and subsequent mineralization in the Jinchuan deposit, which may also be applicable to other magmatic deposit worldwide. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-existing pyrite and calcite with uranium minerals play a significant role in ISL of uranium. • Gypsum produced by pyrite and calcite in CO 2 + O 2 environment disadvantages the leaching of uranium. • Secondary hexavalent uranium minerals will be produced in the ore layer of a neutral environment. Oxidative weathering of pyrite, a widespread iron sulfide mineral, is crucial for the uranium mineralization in sandstone-hosted uranium deposits and the ore utilization leaching under manual intervention. To understand the behavior of pyrite under CO 2 + O 2 leaching conditions in sandstone-hosted uranium deposits, samples of uranium ore from the mineralized zone of the Qianjiadian IV uranium deposit located in the lower section of the Yaojia Formation were collected for this study. The stirring leaching experiment was carried out through the processes of the pyrite-bearing uranium ore samples thinned before and after the reaction, followed by an optical microscopic study and the TESCAN Integrated Mineral Analyzer analysis, and finally, the thermodynamic simulation by making use of PHREEQC3.0. The results revealed the following: (1) The dissolution particles of pyrite become smaller, which may increase the porosity of the ore layer and the exposure ratio of uranium minerals. And more soluble pyrite with a high free surface will be more competitive with uranium minerals for the consumption of O 2. (2) The ion (Fe2+) produced by the dissolution of pyrite will be oxidized to Fe3+ by excess O 2 (4 mol), which provides an oxidant for the oxidation of uranium minerals, and the generated SO 4 2- will combine with the Ca2+ released from calcite to form a permanent precipitate of gypsum, which may block pores and cover the uranium ore. (3) Pyrite and calcite will consume O 2 and CO 2 in the injection system, thus jointly inhibiting the leaching of uranium minerals. After the injection of excessive CO 2 and O 2 , the concentration of Ca2+, SO 4 2-, Fe3+, UO 2 2+, and HCO 3 – in the system will continue to accumulate, resulting in the secondary precipitation of calcite, co-precipitation of gypsum, iron minerals, colloids, and hexavalent uranium minerals, resulting in plugging pores and seriously affecting the effective leaching of uranium. This study contributes to the understanding of the behavior of pyrite during uranium recovery through CO 2 + O 2 leaching. It also contributes to the understanding of quantitative uranium mineralization in sandstone-hosted uranium deposits and process parameters in in-situ leaching (ISL) of uranium. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Hajibolagh-Zalibolagh Cu-(Ag) deposit is hosted by the Eocene volcano-sedimentary sequence. • Fault-controlled sulfides occur with silicification, sericitization, and intermediate argillic alteration types. • pH increases due to boiling, dilution, and mixing causes Cu-Ag saturation. • Hajibolagh-Zalibolagh is an intermediate-sulfidation Cu-(Ag) epithermal system from Saveh, UDMA, Iran. The Hajibolagh-Zalibolagh deposit located northeast of the city of Saveh in the central part of the Urumieh-Dokhtar magmatic arc of Iran, demonstrates vein and breccia vein style copper-(silver) mineralization hosted by Eocene volcano-sedimentary rocks. The main mineralization stage can be divided into four phases, respectively (1) jasperoid + quartz veins, chalcopyrite, and pyrite; (2) quartz veins along with chalcopyrite, bornite, chalcocite, arsenopyrite, and pyrite; (3) quartz-barite veins along with chalcopyrite, bornite, chalcocite and pyrite; and (4) veins of quartz, calcite, hematite, and oligist along with a small number of copper sulfides. The main stages of mineralization are cut by barren post-ore quartz and calcite veinlets. As a result of supergene processes, minerals are oxidized, and malachite, azurite, chrysocolla, chalcocite, covellite, goethite, and hematite are formed, presenting an important exploration guide. The hydrothermal alteration from the center of the vein-veinlets to the outside includes, respectively, silicification, sericitization, intermediate argillic, and propylitic. The average salinity and homogenization temperature (T h) of fluid inclusions is 14.2 wt% NaCl equiv. and 288 °C, respectively. The coexistence of the vapor phase, liquid-rich phase, and halite-bearing fluid inclusions is a sign of boiling in this hydrothermal system, which has contributed to copper saturation. Sulfur isotope values for pyrite, chalcopyrite, chalcocite, and bornite are mainly from –0.16 to 2.98 ‰, indicating a probable magmatic source for sulfur. Boiling, dilution, and mixing are the mechanisms for the ore deposition and facilitated the mineralization. The Hajibolagh-Zalibolagh deposit shows the highest similarity to intermediate-sulfidation epithermal deposits. The best environment for the mineralization and fluid circulation in these epithermal deposits is the intersection of faults with the Eocene volcanic and volcano-sedimentary rocks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Traditional geological and geophysical methods do not perform well for greenfield exploration of orogenic gold deposits. • Possible hydrothermal fluid channel can be identified through geological and SWIR mapping. • Two distinct exploration strategies for surface and drill hole prospecting based on SWIR data. Widespread regolith cover makes it difficult to identify the anomalous size of their mineralogical or geochemical footprint at the surface in gold exploration. Short wavelength infrared (SWIR) spectroscopy with effective identification of clays and other hydrous minerals shows potential application in gold exploration. The detailed geological and short wavelength infrared (SWIR) spectroscopy mapping was conducted in the newly-discovered orogenic-type Mailong gold deposit (13.06 t @ 6.29 g/t Au), East Kunlun, to determine alteration stage and mineral assemblages and discuss the potential values of SWIR spectral in gold exploration. In the Mailong area, magmatic rocks consist of granodiorite, biotite granodiorite, plagiogranite and mafic dikes, and the gold mineralization shows a close spatial and temporal relationship with mafic dikes. The earliest chloritization (chlorite-quartz) is widely distributed in granodiorite, biotite granodiorite and plagiogranite. The following potassic alteration (hydrothermal K-feldspar and quartz) is developed along high-angle fault/fracture, which cut through granodiorite, biotite granodiorite and plagiogranite. The subsequent sulfide alteration (chlorite-muscovite-sulfide-carbonate) overprints the former potassic and chloritization alteration, and shows spatial association with mafic dikes. Native gold occurs in fracture arsenopyrite or associated with minerals such as pyrite, and chalcopyrite during the early sulfide stage. Supergene alteration is characterized by limonite and malachite. At Mailong, the SWIR data indicate that the most abundant alteration minerals (chlorite, white micas and ankerite) mainly occurred in the northern area. White mica Al-OH absorption occurs at longer wavelengths (Pos2200 = 2202.5 ∼ 2203 nm) and higher Illite crystallinity (IC = 1.2 ∼ 3.1) probably reflecting a higher temperature and pH conduit at the bottom of ZK0001 and ZK0801. The sharp shift of IC values near the bottom reflects the control of fault. This area is also situated at the V-shaped intersections of the three granitic intrusions and structural transection, indicating more of a possible hydrothermal fluid channel than a mineralization center. Low-grade Au mineralization (Au = 0.1 ∼ 0.5 g/t) is mainly distributed within hydrothermal channels with higher Pos2200 (mainly 2022.5 ∼ 2203 nm) and IC values (mainly 1.2 ∼ 3.1), while high-grade Au endowment associated with mafic dikes has low Pos2200 (mainly 2201 ∼ 2202.5 nm) and IC values (mainly 0.43 ∼ 1.2). Meanwhile, an equation of distance = -15*IC + 31 (R2 = 0.47) can be summarized for low-grade orebodies vectoring. Integrating geological mapping and spectral data, target areas for high-grade ore bodies can be outlined using the criteria of white mica, shorter wavelength of Al-OH absorption position (Pos2200 = 2201 ∼ 2202.5 nm), lower IC values (IC = 0.43 ∼ 1.2), and chlorite Fe-OH absorption position Pos2250 (>2247 nm) along with occurrences of mafic dikes. This study demonstrates that utilizing the detailed SWIR identification in conjunction with accurate geological mapping has great potential for greenfield exploration of orogenic gold deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • Exploration of gold. • Variation in homogenization temperatures and electrolytes observed at all scales. • Textural and fluid inclusions assemblages with evidence of boiling and flashing. • The importance of rapid coseismic dilation induced at specific structural sites such as dilational fault jogs and bends. The Alhué mining district (AMD) of the Coastal Range in Central Chile is situated approximately 70 km southwest of the city of Santiago and hosted in stratified Jurassic and Early Cretaceous sequences which are common in central Chile. More than 79 faults and veins are recognized in the AMD hosted in andesites and tuffs with clear structural control showing two distinct trends. Precious‐metal mineralization locally extends over strike lengths of up to 1000 m along these structures with grades averaging at 5 ppm gold and 23 ppm of silver. In this study, a University of Chile – YAMANA GOLD joint research project was created to better understand this particular deposit and explore the origin of gold anomalies found in the district using drill core, mine, and surface samples. Wide internal variations in homogenization temperature and electrolytes were observed at all scales: on the district scale, in mineralized structures intersected in drill core, and in hand specimens. This variability may reflect the diversity of ore-forming conditions in the mining district in addition to the different processes (including fault motion over time) and geochemical components within the district. Textural analyses and fluid inclusion assemblages (FIA) provide evidence for boiling and flashing mechanisms at several localities. Raman spectroscopy and LA-ICP-MS techniques allowed a better characterization of the fluid composition and mineral paragenesis. The presence of gold (∼3.8 ppm) and silver (∼1424 ppm) in both vapor-rich only FIAs (i.e. that contain 99 % vapor) hosted in quartz and liquid-rich FIA hosted in sphalerite implies that gold was transported as sulfide and chloride complexes. The AMD shows a transition from a high temperature environment (sometimes containing calc-silicate minerals) to a low temperature (epithermal) system. This mineralization depended on the type of vein system which tend to be mineralized in strike slip faults e.g. Maqui and Lorena structures. The consequence of flashing documented at dilational jogs, structural intersections and fault bends was likely an important outcome leading to the precipitation of metals at the AMD. Coexisting liquid-rich and vapor-rich fluid inclusions contained in a FIA were observed at the deepest levels in the Chilco vein and the proportion of samples showing boiling increases with depth, indicating that additional precious metal resources may be present below current exploration depths. In summary, our new results reveal that gold, silver and base metal veins found at the AMD in Chile are unique hydrothermal polymetallic ore deposits that are structurally controlled and related to an orogenic environment. A general model for the AMD is one where high temperature fluids from deep crustal mafic magmatic systems, probably as products of a devolatilization and far-from-equilibrium conditions, reach subsurface conditions along faults and are mineralized along these faults. Because having a truly unique ore deposit in the geologic record is very unlikely, the AMD forms an important case study that helps understand structurally controlled ore deposits. Thus our work can form a model for future exploration in the AMD and provide insight into exploration in other sites in Chile and along continental margin settings worldwide, in both poorly characterized known deposits and at greenfield sites. [ABSTRACT FROM AUTHOR]

Figure. Stereoscopic slice of inverted resistivity-elevation section. The hidden conductive bodies detected in this study serve as significant indicators for mineral exploration. A blue low-resistivity body, inferred to be mineralized pyroxenite, was identified at depths ranging from 80 to 150 m. The mafic body extends deeper towards the southwest, and mineralized pyroxenite is observed beneath the mafic gabbro, as indicated by the distribution characteristics of the low-resistivity anomaly. The degree of mineralization gradually decreases from northeast to southwest, and there are conductive mineralized anomalies at greater depths below the known exposed intrusion, pointing towards promising prospects for exploration. Magma channels have been observed beneath the mineralized intrusion. The magma upwells into the shallow gneiss through high-angle fractures and subsequently migrates horizontally. This lateral migration is influenced by density differences, resulting in the formation of the current spatial relationship between the mafic gabbro and ultramafic pyroxenite. [Display omitted] • The mafic body extends to a greater depth towards the southwest. • The mafic body extends to a greater depth, and mineralized pyroxenite was observed beneath the mafic gabbro. • Conductive mineralized anomalies are present at considerable depths below the known exposed intrusion. • The magma upwelled along fractures into the shallow gneiss and subsequently migrated horizontally. The Xiarihamu magmatic Ni-Cu sulfide deposit is situated within the East Kunlun Orogenic Belt and consists of four intrusions. While the estimated Ni resources of intrusion No. 1 exceed 1.2 million tons, the resource potential of other intrusions remains unknown. One significant factor contributing to this knowledge gap is the lack of effective detection and localization methods for concealed intrusions. To address this issue, we conducted an electromagnetic study focusing on intrusion No. 2. Due to the substantial topographic relief in the survey area, the conventional artificial-source electromagnetic method presented limitations in data acquisition. Consequently, we employed the short-offset transient electromagnetic method for data acquisition. A group-network observation mode was utilized to reconstruct the electrical structure of intrusion No. 2 through data inversion. Our results reveal a predominant high-resistivity background within the survey area. Rocks including granite, biotite gneiss, gabbro, and pyroxenite exhibit high resistivities, whereas mineralized ultramafic rocks show lower resistivities due to the presence of sulfides. The detection of concealed conductive bodies serves as a crucial indicator for deep mineral exploration. The distribution characteristics of low-resistivity anomalies indicate that the mafic bodies extend deeper towards the southwest, with mineralized pyroxenites observed beneath the gabbros. The results also suggest a gradual weakening of mineralization from the northeast to the southwest, with conductive mineralized anomalies existing at considerable depths beneath the known exposed intrusion. These findings highlight promising prospecting potential and provide valuable insights into the formation of intrusions within the Xiarihamu deposit, supporting resource exploration in similar deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • Temperature, f O 2 , and compositions of fluids control trace element occurrence in sulfides. • Gold occurrence is invisible as solid solution and visible as micron-sized electrum. • Incorporation mechanisms of invisible gold are different by structurally bound gold. • Prolonged interaction generates Cu (–Au) mineralization in IOCG-like deposits. Gold (e.g., electrum) has been reported in the Paleozoic Heijianshan Fe–Cu (–Au) or iron oxide–copper–gold-like (IOCG-like) deposit in the Eastern Tianshan, but relationships between gold occurrence and sulfides are unclear. The Heijianshan Fe–Cu (–Au) (or IOCG-like) deposit underwent five alteration and mineralization stages: Pre-ore epidote alteration (Stage I), syn -ore magnetite/iron mineralization (Stage II) followed by pyrite alteration (Stage III) and Cu (–Au) mineralization (Stage IV), and post-ore late veins (Stage V). This deposit mainly has two types of pyrite (A and B) based on pyrite–hematite and pyrite–pyrrhotite–chalcopyrite assemblages. They are euhedral to subhedral and mainly homogenous, with the former having porous or inclusion-rich domains. Trace elements incorporating into pyrite at Heijianshan are mainly controlled by compositions (e.g., As, Co, and Cu), temperature (e.g., Ni and Se), and oxygen fugacity (f O 2 ; e.g., As and Se) of hydrothermal fluids, respectively. The time-resolved depth-concentration profiles suggest trace elements in pyrite and chalcopyrite occur as solid solution (e.g., Co, Ni, Zn, As, and Se) and micro- to nano-sized mineral inclusions (e.g., Cu, Bi, and Pb). The gold occurrence at Heijianshan is invisible as solid solution in Stage III pyrite and Stage IV chalcopyrite and visible as micron-sized Stage IV electrum. Moreover, incorporation mechanisms of invisible gold are Au3+ substituting iron or copper in pyrite A and chalcopyrite, respectively, and Au+ incorporating into the vacancy or defect positions of pyrite B. Sulfides texture and geochemical compositions when combined with previous in-situ sulfur isotope suggest that pyrite formation was resulted from interaction between external basinal brines and altered host rocks under different temperature and f O 2 conditions. Ongoing fluid-rock reaction led to formation of chalcopyrite ± electrum veins as Cu (–Au) mineralization at Heijianshan. This study suggests that the prolonged interaction contributes to sulfide formation and Cu (–Au) mineralization in these Paleozoic Fe–Cu or IOCG-like deposits formed in basin-related setting, and the Aqishan-Yamansu belt, Eastern Tianshan has gold mineralization potential. [ABSTRACT FROM AUTHOR]

[Display omitted] • LA–ICP–MS analysis of individual fluid inclusions from the Jinman sediment-hosted vein-type Cu deposit was performed. • The ore fluids in the Jinman deposit were metamorphic in origin. • The Jinman deposit has many similarities to orogenic Au deposits worldwide and thus can be thought of as an orogenic deposit. • Implications for global metallogeny and exploration of this type of deposits were highlighted based on the compiled data. Sediment-hosted Cu deposits, including stratiform and epigenetic vein-type Cu deposits, are the second largest source of Cu worldwide. However, many facets of these vein-type Cu deposits, such as the nature and origin of ore fluids and geodynamic mechanisms that produced these fluids, remain controversial, limiting our interpretations of the ore genesis and hampering the selection of exploration strategies. Numerous sediment-hosted vein-type Cu deposits are present in the Lanping Basin, SW China, of which the Jinman deposit is the largest. Copper orebodies at Jinman consist of Cu-sulfide–quartz–carbonate veins and altered wall-rocks hosted mainly in faults and fracture zones in metamorphosed and deformed clastic rocks. The deposit was formed in three stages, pre-, syn- and post-ore, with the first two stages producing hydrothermal veins. The veins in pre-ore stage consist of quartz + ankerite ± sericite ± pyrite, whereas those in syn -ore stage consist of Cu-sulfides + quartz + carbonate ± sericite. During the syn -ore stage, tennantite, quartz, and ankerite crystallized early, then bornite was precipitated, followed by chalcopyrite and chalcocite and finally calcite. Only minor sericite was formed during the post-ore stage. Two major types of fluid inclusions—CO 2 -rich and aqueous inclusions—are present in both pre- and syn -ore quartz, whereas only aqueous inclusions are present in syn -ore calcite. In pre- and syn -ore quartz and calcite, CO 2 -rich inclusions have higher homogenization temperatures (275–323 °C) and pressures (307–3495 bar) and lower salinities (0.22–2.7 wt% NaCl eqv.) than aqueous inclusions (164–299 °C, 6.5–80.4 bar and 3.7–20.9 wt% NaCl eqv.). However, the small variations in Cs/Na and Cs/(Na + K) ratios [log Cs/Na = –3.3 ∼ –1.9, log Cs/(Na + K) = –3.3 ∼ –2.1] of the fluid inclusions suggest a same source for the ore fluids. We propose that during both stages, CO 2 -rich inclusions resulted from unmixing of initial deep-seated, single-phase CO 2 -rich fluids, whereas aqueous inclusions likely represent the fluids that evolved from these unmixed fluids by extensive CO 2 degassing. This interpretation, combined with microthermometric results of CO 2 -rich inclusions, suggests a mesothermal, low-salinity H 2 O–NaCl–CO 2 ore fluid system. The fluid inclusions from Jinman have similar compositions to those of metamorphic fluids, suggesting a metamorphic origin for the ore-forming fluids. The evolution of fluid compositions suggests that fluid degassing likely acted as a major mechanism for Cu precipitation. We propose that the ore fluids were generated through metamorphic devolatilization of basement of the Lanping Basin in the Biluoxueshan–Chongshan metamorphic zone under a compressional or transpressional regime caused by Cenozoic India–Asia collision. The Jinman deposit has many similarities to orogenic gold deposits worldwide and thus can be thought of as an orogenic deposit. Based on a compilation of the geological characteristics of global sediment-hosted epigenetic vein-type Cu deposits, we suggest that other sediment-hosted epigenetic vein-type Cu deposits with similar genesis to the Jinman deposit are likely present in other regions worldwide. This highlights the exploration potential of this type of deposit in these regions and the need for further research. [ABSTRACT FROM AUTHOR]

[Display omitted] • Based on the EPMA analyses, sulfosalts were identified at the Chodarchay deposit. • The chalcopyrite and sphalerite host solid-solution Ag, and the chalcopyrite hosts Ag-sulfosalt. • The sphalerite hosts nano-Au. The Au-Ag exists in the neyite, emplectite and gustavite. • The sphalerite precipitated from 220 to 280 °C, Bi assemblages at > 350 °C. • The supergene enrichment of Ag and Au depends on the presence of Mn. The Chodarchay overprinting epithermal on porphyry mineralization occurs in the Tarom-Hashtjin subzone of the Alborz magmatic arc in northwestern Iran. Rock units include intrusions (phases I and II) and volcano-volcaniclastic rocks. The alteration types consist of potassic, phyllic, argillic, and propylitic. The porphyry type is mostly accompanied by potassic alteration. The Chodarchay Fault implies two extensional and compressional mechanisms. The porphyry type is associated with the extensional and the epithermal type with the compressional stage of the fault. Mineralization occurred mainly inside the Eocene volcanic and volcano-sedimentary rocks; some ores are associated with the Late Eocene quartz monzonite. The mineralization is divided into three zones from depth to surface: 1) Hypogene sulfide zone (deep); 2) Enriched supergene sulfide zone (near-surface); 3) Oxidized and leached zone (surface). The major sulfide minerals consist of chalcopyrite, pyrite, sphalerite, and galena. Based on the results of the new analyses, chalcopyrite hosts Ag as a solid-solution and contains Ag-rich Bi-sulfosalt micro-inclusions. Non-constant Cd/Zn ratio in the chalcopyrite can indicate varying physiochemical conditions during its crystallization. Low As contents in the pyrite caused relatively clean pyrite with very few elements. The Ni concentrations in the pyrite imply that it was sourced from mantle mafic–ultramafic rocks. Sphalerite is the only Au-host mineral among the sulfide minerals as a nano-mineral phase. Solid-solution Ag exists in the sphalerite. The sphalerite Fe/Zn ratios show that it was precipitated between 220 and 280 °C. Silver and Bi have the highest measured concentrations among all analyzed elements in the galena, mainly partitioning within the galena, but Hg and Cd are abundant in the sphalerite. Bornite is one of the major carriers of Ag and Bi. Silver and Bi exhibit considerable variations in the Cu-(Fe) sulfides. A new occurrence of sulfosalt minerals was identified at Chodarchay (N = 14). The discovered Bi-sulfosalts include cuprobismuthite group minerals (cuprobismuthite, hodrushite, and paderaite), aikinite-bismuthinite series (aikinite and friedrichite), emplectite, makovickyite, galenobismutite, gustavite, heyrovskyite, neyite, cupropavanite; and As-Sb-bearing Cu sulfosalts (watanabeite and colusite). This number of sulfosalts had not previously been reported from any of the Tarom or Alborz deposits or mines. The Au-Ag occurrence was reported from the neyite, emplectite, and gustavite. The Ag-rich minerals crystallize from fractionated fluids that cooled during rising. Silver-carrier sulfosalts may have been exsolution from pre-existing Ag-bearing chalcopyrite in the cooling system. Most of the Ag-bearing sulfosalt minerals formed at the margins and fractures of the chalcopyrite, indicating that the cooling started from these points. Thus, Ag at Chodarchay is hosted inside Cu-(Fe) sulfides, the significant part of them being chalcopyrite and Ag-rich sulfosalt micro-inclusions inside the chalcopyrite. The fluid temperature for the Ag and chalcopyrite precipitation is from 200 to 350 °C. Bismuth assemblages precipitated at > 350 °C. The cuprobismuthite group crystallizes at temperatures > 300 °C. The supergene process and rare secondary enrichment of Ag and Au took place in the oxidation zone; this enrichment is dependent on the presence of manganese. Based on the fire-assay results, the concentration of gold is greater at shallower depths. [ABSTRACT FROM AUTHOR]

We suggest that the predominant hypogene alteration assemblage, present Alto de la Blenda monzonite and volcaniclastic Morada Central andesitic breccia, is indicative of deeper-seated, transitional magmatic-hydrothermal systems (>1 km depth), which are generally controlled by fluid cooling. The identified supergene dioctahedral smectite-kaolinite-interstratified chlorite/smectite-interstratified R1 illite/smectite assemblage that replaces the hypogene alteration assemblage along the permeable fault and fracture zone network, associated with veins, could serve as a vectoring tool for concealed, deeper-seated, epithermal veins in arid climatic regions. [Display omitted] • We suggest that the predominant hypogene alteration assemblage (quartz-interstratified-R3 illite/smectite-chlorite-calcite-pyrite ± illite), present in the Alto de la Blenda monzonite and volcaniclastic Morada Central andesitic breccia, is indicative of deeper-seated, transitional magmatic-hydrothermal systems (>1 km depth), which are generally controlled by fluid cooling. The identified supergene dioctahedral smectite-kaolinite-interstratified chlorite/smectite-interstratified R1 illite/smectite assemblage that replaces the hypogene alteration assemblage along the permeable fault and fracture zone network, associated with veins, could serve as a vectoring tool for concealed, deeper-seated, epithermal veins in arid climatic regions. The Farallón Negro deposit is located in the Farallón Negro Volcanic Complex (FNVC; ∼9.40 to 4.88 Ma) in NW Argentina and includes intermediate-sulfidation, epithermal Au-Ag mineralization in the Alto de la Blenda deposit. Detailed mineralogical and geochemical investigations of the Esperanza-Esperanza Sureste, Cecilia veins, both hosted in the Alto de la Blenda monzonite, and the Laboreo vein, hosted in the volcaniclastic Morada Central andesitic breccia, reveal four hypogene vein stages. Each of these four stages are comprised of a texturally early quartz, followed by a sulfide-sulfosalt and a late Mn-carbonate sub-stage. Stage 1 is characterized by a quartz, base metal and Mn-carbonate sub-stage showing high δ18O VSMOW (δ18O Quartz = 13.7 ± 0.4‰ and δ18O Mn-Calcite = 11.6 ± 0.2‰) and low δ13C VPDB values (δ13C Mn-Calcite = –4.7 ± 0.2‰). Stage 2 includes most gold and silver minerals in a tennantite-tetrahedrite-sphalerite-pyrite-galena±electrum sub-stage. Fluid inclusions trapped in vein-anhydrite, only associated with stage 2, record the highest temperatures (T Entrapment = 327–335°C) and highest salinity (3.8 NaCl eq. wt.%) when compared to all other stages. Stage 2 quartz (δ18O Quartz = 9.9 to 11.9‰) and carbonate display lower δ18O VSMOW (δ18O Mn-Calcite = 7.9 to 10.3‰), as well as lower δ13C VPDB values (δ13C Mn-Calcite = -5.2 to 4.7‰) than all other stages. Stages 3 and 4 consist of barren quartz and carbonate sub-stages that show lower temperatures (T Entrapment = 187–262°C) and higher δ18O VSMOW (δ18O Quartz = 13.4 to 13.9‰ and δ18O Mn-Calcite = 10.7 to 11.8‰) and δ13C VPDB values (δ13C Mn-Calcite = –3.5 to −3.9‰) when compared to earlier stages. Petrographic, sulfide mineral chemistry, microthermometric, and stable isotope data combined with distinct alteration mineral assemblages allow the reconstruction of a model for the Alto de la Blenda deposit. During the hypogene hydrothermal fluid flow stage, around 7.16 Ma, at ∼2.2 km depth (P HYDROSTATIC = 220 bars), the high temperature alteration mineralogy, low fluid salinities and 18O and 13C isotope compositions indicate cooling of ascending magmatic-hydrothermal fluids. These fluids were derived from a contracted magmatic vapor phase that exchanged with unexposed sedimentary rocks of the Sierras Pampeanas. Hypogene quartz-R3 illite/smectite-chlorite-calcite-pyrite alteration in the andesitic-breccia and quartz-illite-R3 illite/smectite-chlorite-calcite-pyrite alteration in the monzonite are temporally and spatially to the hydrothermal vein minerals deposited between 187 and 335°C. During the post-hydrothermal supergene weathering event, around 2.70 Ma, sulfuric acids generated by meteoric fluids and supergene oxidation of hypogene sulfides, particularly pyrite, descended along normal fault zones and related vein and fracture networks to at least 450 m depth below the surface level, forming the supergene alteration assemblage of dioctahedral smectite-kaolinite-Mn-/Fe-oxides/-hydroxides-gypsum±interstratified chlorite/smectite±interstratified R1 illite/smectite in both wall rock types at temperatures <50°C. The dominant hypogene alteration assemblage, present in the monzonite and volcaniclastic andesitic breccia, may be indicative of deeper-seated, transitional magmatic-hydrothermal systems (>1 km depth), generally controlled by fluid cooling, as is the case at Farallón Negro. Pervasive supergene alteration can conceal these systems but the identified supergene alteration assemblage of dioctahedral smectite-kaolinite-interstratified chlorite/smectite-interstratified R1 illite/smectite that replaces the hypogene alteration assemblage along the permeable fault, vein and fracture zone network may present a useful vectoring tool towards concealed, deeper-seated, epithermal Au-Ag mineralization in arid climates. [ABSTRACT FROM AUTHOR]

[Display omitted] • The dissolution-reprecipitation process is the dominant post-hydrothermal modification mechanism in the Hongtoushan deposit. • The superimposed fluid was derived from magmatic fluid. • The ferrous ions partially oxidized to ferric iron and precipitated as magnetite together with ferrous ions. The Hongtoushan copper-zinc deposit is a highly metamorphosed Archean volcanogenic massive sulfide deposit (VMS) in China. After metamorphism, the deposit underwent later fluid superimposition, which is of significance for the re-distribution of metals and upgrading ores. However, the hydrothermal modification mechanism and fluid source remain unclear due to the difficulties in accurately recognizing the mineral textures and assemblages formed by hydrothermal modification. In this study, the mineral texture was investigated to identify the modification mechanism of later fluid and in situ sulfur isotope and trace elements of chalcopyrite were tested to track the source of later fluid and metals. The dominant assemblage formed by superimposed fluid consisted of pyrite, chalcopyrite, sphalerite, minor galena, magnetite, calcite, anhydrite, and hydrothermal alteration minerals, i.e. sericite and chlorite. These minerals infilled the fractures in early pyrite porphyroblasts or precipitated along the grain boundary. Additionally, the pre-existing sulfides were corroded by these minerals. They exhibited replacement and porous textures, indicating that the superimposed fluids resulted in a dissolution-reprecipitation process and formed new sulfides. The hydrothermal metasomatism produced the sericitization of plagioclase and chlorization of biotite, which concurrently liberated silica to form silicification. These interactions suggested that the hydrothermal fluid is acid fluid. The chlorite geothermometer defined the formation temperature of 226–279°C, implying that the superimposed fluid has a moderate temperature. The chalcopyrite precipitated from superimposed fluid either coexisted with pyrite (Ccp 2a) or magnetite (Ccp 2b). The sulfur isotope of Ccp 2a defined a closing zero range (0.75–2.41‰), demonstrating the superimposed fluids were derived from magmatic fluids. In contrast, the Ccp 2b enriched heavy sulfur with a δ34S range of 4.10–8.63‰, which was attributed to the oxidation of fluids. Partial ferrous ions were oxidized to ferric iron, and ferrous and ferric iron precipitated as magnetite. The mineral assemblage changed from chalcopyrite + pyrite, followed by magnetite + chalcopyrite + pyrite, to magnetite + pyrrhotite, representing the local increase of the oxidation state of hydrothermal systems. During the oxidation process, the oxygen fugacity of the superimposed fluid decreased, whereas the pH increased. These results provide crucial evidence on the re-distribution pattern of metals and the post-hydrothermal modification process in the Hongtoushan Cu-Zn deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anhydrite REE concentrations reflect seafloor hydrothermal mineralization conditions. • Host rock compositions have little effect on the anhydrite REE systematics. • The low redox potential of hydrothermal fluids is a major control on Eu mobility. • Fluid boiling plays an important role in determining the mobility of LREE. • Magmatic volatile input and limited fluid-seawater mixing produce REE-rich anhydrite. Comparative studies of sulphide chemistry have been conducted over the past few decades to characterise seafloor hydrothermal mineralisation, but few studies have been carried out on sulphate minerals. Here we report on a systematic study of the S isotopic composition and rare earth element (REE) chemistry of chimney anhydrite from various types of seafloor hydrothermal vent fields in the Central Indian Ridge, North Fiji Basin, and Tonga intra-oceanic arc. Our results show that sulphate δ34S values of anhydrite cluster around that of seawater sulphate, indicating a significant role for fluid–seawater mixing during anhydrite precipitation. However, some anhydrite has δ34S values lower than that of seawater. This likely reflects sulphate derived from magmatic SO 2 disproportionation. Chondrite-normalised REE patterns of the anhydrite are not uniform on the scale of individual grains and/or between each type of hydrothermal vent field. The REE compositions of the anhydrite do not have a clear relationship with the REE compositions of the primary host rocks with which the hydrothermal fluids interacted. This indicates that the REEs are not sensitive indicators of the host rock compositions, even though the host rocks are the dominant source of REEs in the seafloor hydrothermal fluids. In contrast, anhydrite REE concentrations and Eu anomalies are correlated with δ34S values and the redox state of the hydrothermal fluids, respectively. We suggest that relatively REE-enriched anhydrite is formed by efficient leaching of REEs from host rocks by acidic magmatic fluids (i.e., a low pH), whereas a low redox potential of the hydrothermal fluids is the most important factor controlling Eu mobility. The original concentrations of REEs supplied to the hydrothermal fluids can also be modified by fluid boiling and fluid–seawater mixing. The former produces light REE-depleted anhydrite because the availability of chloride ligands decreases in low-density vapor-dominated boiled fluids. In situ geochemical analysis of anhydrite on the intra-grain scale shows that high degrees of fluid–seawater mixing contribute to the relatively low REE concentrations and positive Eu anomalies. As such, our results indicate that the REE systematics of anhydrite are mainly controlled by the combined effects of fluid conditions (i.e., redox state, pH, and Cl concentrations) and sub-seafloor geochemical processes (i.e., magmatic input, fluid boiling, and seawater mixing) rather than the nature of the source materials. In situ analysis of anhydrite grains is a useful tool for constraining variable hydrothermal mineralisation conditions during chimney growth, which cannot be solely inferred from geochemical studies of sulphide minerals, particularly in inactive and relict systems where the hydrothermal fluids cannot be sampled. [ABSTRACT FROM AUTHOR]

[Display omitted] • Latest Oligocene–Miocene arc magmatism in central Oaxaca developed in a thick continental crust. • Early–mid-Miocene metallogenic epoch in southern Mexico comprises Au-Ag rich epithermal deposits. • Precious metal-rich intermediate-sulfidation epithermal deposits occur at Natividad. • Detailed vein stratigraphy reveals multi-episodic fluid pulses and interaction with wall rocks. • First formal report of argyrodite (Ag 8 GeS 6) in Mexico. The final magmatic arc—Miocene in age—of the long-lived Sierra Madre del Sur igneous province in southern Mexico hosts several epithermal deposits that have hitherto received little attention. The Natividad Au-Ag(-Ge) epithermal deposit is one of them and holds a mining record of > 200 years. Here, we present the first petrogenetic and metallogenic study on the Natividad deposit, in which we use a multi-methodological approach to assess the genesis and evolution of the deposit and its associated igneous rocks. Natividad is mostly hosted by Oligocene–Miocene arc-related dacites (U-Pb zircon dates of 22.8–24.7 Ma), whose geochemical features suggest lower-crustal differentiation (i.e., involvement of garnet) at the base of a thickened continental crust. The mineralization occurs in three multi-stage quartz + carbonate veins and consists of Fe-poor sphalerite (<5 mol. % FeS), galena, chalcopyrite, acanthite, and marcasite (sulfide-dominated stage) overprinted by pearceite-polybasite, pyrargyrite-proustite, tetrahedrite-group minerals, electrum, and argyrodite (Ag 8 GeS 6 ; Ag-sulfosalt-dominated stage). Geothermometry and fluid inclusion data for ore-bearing assemblages reveal fluid temperatures of 170°–400 °C and salinities of 14.6–19.5 wt% NaCl equiv. δ18O from 0.8 ‰ to 7.5 ‰ in mineralizing fluids suggests mixtures of magmatic brines and meteoric waters, while δ13C from –8.4 ‰ to 2.2 ‰ indicates the recycling of organic carbon from the meta -sedimentary basement. Further, δ34S from –3.2 ‰ to –0.3 ‰ in sulfides attest to magmatic S. These results align with an intermediate-sulfidation epithermal model, whereby upwelling magmatic ore-bearing brines precipitated the ores due to conductive cooling, dilution, and, locally, boiling. Our study highlights the metallogenic potential of Miocene magmatism in the eastern Sierra Madre de Sur. [ABSTRACT FROM AUTHOR]

Metal mobilization event was linked to shear-associated granodiorite magmatism. [Display omitted] • Um Samiuki volcanogenic massive sulfide deposit in Egypt's South Eastern Desert. • Zircon U-Pb and sulfide Re-Os dating reveal the genetic link with the host rocks. • Ore-hosted stratum formed ∼700 Ma, and a crosscutting granodiorite at 624 Ma. • Sulfide minerals show high Re-Os ratios and crustal isotope signature. • Ductile shearing formed discrete sulfide masses, followed by intermittent brittle deformation. • Ag-mineral inclusions in galena and solid solution in sulfides contribute to Ag budget. The Um Samiuki deposit in the South Eastern Desert of Egypt is a Kuroko-type volcanogenic massive sulfide deposit associated with arc-related bimodal volcanic rocks. SIMS U-Pb zircon ages of the host metavolcanic rocks and a crosscutting granodiorite intrusion are integrated with Re-Os isotopes of ore sulfides, allowing the determination of the genetic relationships between sulfide mineralization and host rocks to be determined. Zircon U-Pb dating reveals that the ore-hosted stratum of banded tuffs formed at ∼700.0 ± 7.3 Ma, whereas the granodiorite yielded a concordia age of 624.0±8.5 Ma. Sulfide mineral separates (pyrite, sphalerite, chalcopyrite) and sulfide mixtures from the massive ores have significantly high radiogenic Re-Os concentrations and ratios. Regression of seven 187Re/188Os-187Os/188Os data points with the corresponding uncertainty correlation values yields a 624±46 Ma age (2σ, MSWD = 0.56), with an initial 187Os/188Os ratio of 3.58±0.7, thereby pinpointing a distinctive crustal isotope signature. Evolution towards textural equilibrium by recrystallization, as revealed by grain growth and annealing textures in the ores, suggests that ductile shearing and penetrative deformation of the host metavolcanic/metavolcaniclastic rocks led to the formation of discrete sulfide disseminations and masses. Deformed, rolled and rotated pyrites in veins and tension gashes with or without quartz evidently suggests an intermittently rejuvenated brittle deformation regime superimposed on the early ductile deformation textures. Pyrite, galena, chalcopyrite, and sphalerite contain elevated Ag contents between 5 and 812 ppm. Two pyrite generations can be distinguished with the earlier one (Py1) having the highest Ag contents of all sulfides. Silver was released during replacement of Py1 by a late assemblage (Py2-galena-chalcopyrite-sphalerite) with some Ag incorporated into the late sulfides but most Ag was released and retained in discrete Ag minerals like cerveilleite, hessite and acanthite. Time-resolved analyses of LA-ICP-MS data reveal the presence of micron-scale Ag-bearing inclusions in galena while other base metal sulfides also contribute a notable part to the Ag budget of Um Samiuki ore. The new geochronological data integrated with results of the microscopic and microanalytical analyses of the sulfide phases provide an updated insight into a metal mobilization event in the Um Samiuki volcanogenic massive sulfides, roughly coincided with shear-associated granodiorite magmatism. [ABSTRACT FROM AUTHOR]

[Display omitted] • S ulfide minerals from Hongtoushan Cu-Zn-Au deposit have slightly various δ34S Δ33S values. • The slightly negative mass-independent fractionation indicates a dominant igneous source of sulfur with ∼2.5–3.5 % seawater sulfate contribution. • Multiple sulfur isotope analyses may be used to predict the size, the grade of Cu, and the grade of Au for the Archean VMS deposits. In-situ multiple sulfur isotope analyses of pyrite, pyrrhotite, and chalcopyrite from the ∼2.55 Ga Hongtoushan Cu-Zn-Au VMS deposit are reported. Three sulfide minerals (pyrite, pyrrhotite, chalcopyrite) display slightly different mean δ34S values of +0.94 ‰, +0.60 ‰, and +0.57 ‰ and mean Δ33S values of –0.07 ‰, –0.02 ‰, and –0.05 ‰, respectively. The sulfide minerals show obvious signatures of slightly negative mass-independent fractionation for sulfur isotopes, indicating a dominant igneous source of sulfur with ∼2.5–3.5 % seawater sulfate contribution during the formation of this deposit. According to the suggestion by Chen et al. (2015) that the ore tonnages of Archean VMS deposits are linked to the Δ33S values, the Hongtoushan deposit may have greater prospecting potential. This study also proposes that not only do high Au-grade Archean VMS deposits have relatively high Δ33S values (near-zero) as suggested by Sharman et al. (2015), but low Au-grade Archean VMS deposits might also have high Δ33S values (near-zero). The Cu grades may also be directly linked to the Δ33S values for the Archean VMS deposits, as a greater seawater contribution (rapid temperature decrease; more negative Δ33S values) would be linked to higher Cu grades. These new findings may have great implications for our understanding of Archean VMS deposit genesis, and multiple sulfur isotope analyses may be used to predict the size, grade of Cu, and grade of Au for Archean VMS deposits. [ABSTRACT FROM AUTHOR]

• Texture and trace element geochemistry of quartz from Jiguanzui Cu–Au skarn deposit were proposed. • Neutralization of the acidic ore fluids may be an important cause of metal sulfide precipitation at Jiguanzui. • Quartz Al/Ti ratio could be used to distinguish skarn deposits from orogenic-, porphyry- and epithermal-type deposits. The Jiguanzui Cu–Au deposit is an important skarn deposit in the Edong ore district of the Middle–Lower Yangtze River Valley Metallogenic Belt (MLYRB), Eastern China. The skarn mineralization occurs dominantly in the intrusive contact between quartz diorite and marble of the Lower-Middle Triassic Jialingjiang Formation. The main mineralization stage (quartz-sericite-pyrite-chalcopyrite) is characterized by abundant quartz, which can be grouped as quartz in orebodies (Qtz1), quartz in quartz-pyrite hydrothermal veins in hornfels of the Middle Triassic Puqi Formation and quartz diorite (Qtz2 and Qtz3, respectively). Cathodoluminescent (CL) imaging reveals core-rim texture in Qtz1 and oscillatory zoning in Qtz2 and Qtz3, suggesting that Qtz1 was formed under low crystallization rate, in a relatively stable closed system, whereas Qtz2 and Qtz3 were formed under high crystallization rate, in an open system with oscillatory physicochemical fluctuations. As the main trace element in the Jiguanzui quartz, aluminum is incorporated into quartz as trivalent Al3+ to substitute Si4+. Monovalent alkali metal (esp. Li+) and divalent cations (Ge2+, Sr2+) act as charge compensators for the Al3+ substitution. Titanium concentrations (mostly <10 ppm) and the clear positive Al vs. Li correlation indicate the main mineralization at Jiguanzui formed under low temperature (<350 °C). Additionally, CL reflectivity of Qtz1 increases from core to rim, suggesting neutralization of the acidic ore fluids, which is interpreted to be an important cause of metal sulfide precipitation at Jiguanzui. [ABSTRACT FROM AUTHOR]

• Diverse fluid signatures are recorded in the Mashitu South deposit, Katanga Cu-belt. • Cu-Co vein mineralization formed during basin inversion and orogenic stages. • Hydraulic fracturing of hematitic siltstones favored deposition of supergene ores. • Migration of metal-rich brines and low salinity fluids is of regional significance. • Barium and potassium-bearing sulfate fluids are linked to Cu transport. The sediment-hosted Mashitu South (Sud) Cu-Co deposit situated in the Katangan Copperbelt (DR Congo) hosts hypogene and supergene mineralization in Neoproterozoic age rocks of the Mines and Red R.A.T. Subgroups of the Neoproterozoic Katangan Supergroup. Detailed and systematic petrographic, fluid inclusion and stable isotope studies of minerals from various generations of stratabound metalliferous veins, crackle breccia, and alteration zones placed significant constraints on the intricate fluid dynamics, compositions as well as origins of ore-forming and ore-upgrading fluid systems at the Mashitu South deposit. Our data document large-scale migration of metalliferous (Cu, ±Co, Zn) high-salinity brines, sulfate-rich fluids and meteoric fluids, which can be regionally followed across the Katangan Copperbelt through deposits tens of kilometers apart from each other. The stratabound, hypogene, hydrothermal Cu-Co ore veins precipitated at high temperatures (∼247–316 °C) from mixed high-salinity Mg-rich/Na-K-Ca-Mg-Cl brines and Ba-K-Na-Ca ± Cl-SO 4 2− fluids and locally operating thermochemical sulfate reduction-TSR as indicated by negative δ13C V-PDB ratios (down to −7.4‰). A number of these veins were subjected to dynamic recrystallization, under the influence of low salinity/meteoric fluids, during active deformation at the onset of the Lufilian Orogeny. Isotopic compositions of dolomites from veins containing spectacularly large carrollite, chalcopyrite, bornite and chalcocite crystals from the Kamoya South II deposit overlap with isotope data from hydrothermal veins from the Mashitu South deposit suggesting a similar nature of the parent fluids. Metalliferous (Cu, Zn) Na-K-Cl brines, which provided metals for giant crystals of carrollite in post-tectonic ore veins from the Kamoya South II deposit originated from seawater evaporation. Besides fluctuations of the water table the brecciation, alteration and dissolution/re-precipitation processes in the Red R.A.T. and the R.S.C. units were essential for deposition of supergene ores at Mashitu South. The quartz-specular hematite-dolomite veins sealing the crackle breccia, which resulted from hydraulic fracturing, precipitated from Na-Ca-Cl-SO 4 2− fluids gaining salinity (<12.7 mass% NaCl equiv.) and compositions through pervasive interaction of low salinity meteoric fluids with formation waters stored in hematitic siliciclastic rocks of the Red R.A.T. Subgroup. Primary mono-phase liquid aqueous inclusions and C-O isotopic signatures of free-growing supergene minerals record T < 50 °C and precipitation from predominantly low salinity freshwaters, with local pulses of saline fluids during the formation of decoupled supergene Cu and Co mineralization. [ABSTRACT FROM AUTHOR]

• Mineralization of the Gongpengzi deposit occurred at ca. 173 Ma. • Granitoids were derived by partial melting of a mixed depleted mantle and crustal source. • Crustal and mantle mixing was important for mineralization at Gongpengzi. The Gongpengzi Cu-Zn-W polymetallic deposit is a typical skarn deposit located in the Lesser Xing'an-Zhangguangcai Range, NE China. Although the deposit was first discovered in the 1950s, the timing of mineralization, source of the ore-forming materials, and geodynamic setting of the deposit, remain unclear. We present whole-rock geochemical and zircon U-Pb geochronological data for granitoids, molybdenite Re-Os geochronological data, and S-Pb isotopic analyses of sulfide minerals and feldspars from granitoids within the deposit. The results of molybdenite Re-Os and zircon U-Pb dating of biotite granites and granodiorite from the Gongpengzi polymetallic deposit suggest that ore formation occurred at 176.7 ± 5.9 Ma, and that the granodiorite hosting the mineralized zone were emplaced at 173.6 ± 1.0 and 173.9 ± 1.0 Ma, respectively. The granites and granodiorites have high SiO 2 and Na 2 O + K 2 O contents, are enriched in Rb, Th, U, Ta, and Pb, and depleted in U, P and Ti, and therefore classify as I-type granitoids. One granodiorite sample yielded a (87Sr/86Sr) i value of 0.70444, ε Nd (t) value of 2.30, and two-stage model age (T DM2) of 785 Ma. The biotite granite samples yielded (87Sr/86Sr) i values of 0.70433–0.70445, ε Nd (t) values of 2.34–2.54, and T DM2 of 785–765 Ma. These observations suggest that the granites were probably derived by partial melting of both mantle and juvenile crustal material, and that these partial melts underwent fractional crystallization. The ore-forming elements were magmatic source, and may have been derived by mixing between crustal and mantle sources. We interpret granitoid relating to skarn mineralization in the Lesser Xing'an-Zhangguangcai Range to have resulted from subduction of Paleo-Pacific oceanic crust toward the Eurasian continent. [ABSTRACT FROM AUTHOR]