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A comprehensive study was conducted to investigate the geochemical characteristics of Sb, Pb, and Zn deposits in various regions of Chitral district. The primary objective was to identify the source and chemical composition of the metal-bearing fluids, which currently remain unidentified. Field research revealed the presence of stibnite (Sb), galena (Pb), and sphalerite (Zn) ores, accompanied by small amounts of chalcopyrite and pyrite. These deposits were found to be associated with the Reshun fault/shear zone, and secondary minerals such as quartz and calcite were observed. Ore petrography, in combination with SEM-BSE and SEM–EDS analysis, confirmed the presence of magnetite, chamosite, stibnite, fahlore, galena, litharge, sphalerite, arsenopyrite, zinkenite, chalcostibite, boulangenite, pyrite, as well as a few gangue minerals (specifically quartz and calcite). Atomic absorption spectroscopy (AAS) was employed on four cross-sections to determine the concentrations of the metal-bearing elements. The results revealed varying concentrations of Sb (ranging from 0.001 to 24%), Pb (ranging from 0.006 to 24.1%), Zn (ranging from 1.2 to 158,000 ppm), and Cu (ranging from 0.2 to 2730 ppm). Gold (Au) and silver (Ag) concentrations were predominantly below the detection limit (BDL), except for the Barum Ghari section, where gold concentrations ranged from 0.0 to 0.38 ppm. Integration of field observations, ore petrography, and SEM analysis suggested that the deposition of ores was influenced by metamorphic fluids generated during the progressive metamorphism of sedimentary layers. Furthermore, the AAS results demonstrated an increasing concentration of metal-bearing elements from the lower to the upper Chitral region. [ABSTRACT FROM AUTHOR]

The Murcielago gold placer is located in the Lepaguare Valley, Olancho Department (Central Honduras). The placer mineralogy includes silicates (quartz, garnets, amphibole, Ca-pyroxene, micas, epidote, and tourmaline); calcite; and in the heavy fraction, zircon, ilmenite–rutile, magnetite, hematite, cassiterite, and cinnabar. Gold grains recovered from the Murcielago placer production plant are mainly flattened grains with a moderately to high elliptical shape. The composition of the gold grains varies continuously in the range Au 46 Ag 54 to Au 88 Ag 12 . Few of them are characterized by Au-rich rims of a few microns in size (Ag 3-1 atoms percent (at%)). Gold from the Canan lode deposit, a nearby hydrothermal Au mineralization area, has a composition (from Au 54 Ag 44 to Au 81 Ag 19 ) overlapping the composition of the Murcielago grains. Inclusions in the alluvial gold particles are arsenopyrite, pyrite, acanthite, sphalerite, and hematite. On the basis of the placer mineralogy and the gold grains analyses, possible gold source(s) include the Canan lode and skarn gold deposits in the area. We obtained new data on the Murcielago gold placer that will be the basis for an exploration of the potential sources of gold in the area. [ABSTRACT FROM AUTHOR]

The Elatsite–Chelopech ore field in the northern part of the Panagyurishte district in Central Bulgaria comprises numerous spatially associated porphyry copper and epithermal gold deposits and prospects. In addition to the mineralization and alteration features, trace elements, lead and sulfur isotope signatures of sulfide minerals from porphyry copper, base metal and gold-base metal deposits/prospects have been studied. LA-ICP-MS analyses of pyrite, arsenopyrite and sulfosalt minerals validate them as major carriers for Au, Ag, Sb, Se and Co. Pyrite from the three types of mineralization has specific geochemical characteristics. Pyrite from the porphyry copper deposits/prospects has generally lower total trace element content compared to pyrite from the epithermal prospects, except for Se, Co and Ni. Pyrite from the base metal and gold-base metal veins is enriched in As, Au, Ag, Sb and Pb. In pyrite from the base metal deposits, Co and Ni have contents comparable to the pyrite from the porphyry copper deposits, while pyrite from the gold-base metal veins shows lower Co and Ni. Arsenopyrite from these deposits shows similar features. Similarly, sphalerite from the gold-base metal veins also has lower Co content compared to sphalerite from the base metal veins but higher In and Cu contents. In addition to the close spatial relationships between the Elatsite and Gorna Kamenitsa porphyry Cu deposits and Negarstitsa-West and Dolna Kamenitsa base metal prospects, as well as similarities in the mineralization and alteration styles, the lead isotopic (206Pb/204Pb = 18.61–18.68, 207Pb/204Pb = 15.64–15.65 for porphyry and 206Pb/204Pb = 18.55–18.67, 207Pb/204Pb = 15.64–15.68 for base metal) and sulfur isotopic (δ34S values of −3 to +1‰ for porphyry and δ34S values of −1.7 to +3.5‰ for base metal) signatures of sulfides support the idea of a genetic link between these two types of deposits. The porphyry and base-metal mineralization result from a common major ore-forming event during the Late Cretaceous, corresponding to deep/higher-temperature and shallower/distal/lower-temperature environments, respectively. In particular, more radiogenic lead (206Pb/204Pb = 18.41–18.47, 207Pb/204Pb = 15.67–15.76) and slightly different sulfur isotopic compositions (δ34S values of +3.5 to +10.6‰) of sulfides from the distal gold-base metal veins of Kordunsko Dere, Svishti Plaz and Shipkite might be a consequence of the interaction of the ore-forming fluids with an external older crustal and isotopically positive S source. Alternatively, a different fluid source/event for the formation of these gold-base metal veins may be suggested. [ABSTRACT FROM AUTHOR]

The Heihaibei gold deposit is located in the Eastern Kunlun Orogen in Northwest China. The gold mineralization here occurs predominantly in quartz veins within faulted granite zones. The sulfide mineral assemblage is dominated by pyrite and arsenopyrite, with minor chalcopyrite, galena, sphalerite, tetrahedrite, and micro-native gold. Weak alterations in Heihaibei granites include silicification and sericitization, with minor chloritization and carbonatization. The measured δDH2O and δ18Oquartz values of quartz in auriferous quartz veins range from −104.2‰ to −81.1‰ and +9.2‰ to +13.9‰, respectively. The δ34S values of sulfides in auriferous quartz veins range from +7.60‰ to +8.65‰, and the lead isotope compositions of sulfides in ores range from 18.7219 to 19.0007 for 206Pb/204Pb, 15.6959 to 15.7062 for 207Pb/204Pb, and 37.7359 to 38.8055 for 208Pb/204Pb. The Pb isotope compositions of potassic feldspars from Heihaibei granites vary from 18.3532 to 19.4864 for 206Pb/204Pb, 15.6475 to 15.6812 for 207Pb/204Pb, and 37.1750 to 38.4598 for 208Pb/204Pb. Collectively, the isotope (H, O, S, and Pb) geochemistry suggests that the ore-forming fluid was a special metamorphic water evolved from the deep slab-derived fluids, and the sulfur and lead were predominantly sourced from such metamorphic fluids, and from the deep parts of the Heihaibei granites. Therefore, the Heihaibei gold deposit can be classified as an orogenic gold deposit, which is closely associated with the subduction of the Paleo-Tethys oceanic plate, and even the final closure of this ocean by the Later Triassic. [ABSTRACT FROM AUTHOR]

The stibnite mineralization at Rizana (Kilkis ore district; Serbo-Macedonian metallogenic province; northern Greece) occurs along a NE–SW-trending brittle shear-zone, which transects a two-mica and an augen-gneiss of the Vertiskos Unit. Barren Triassic A-type granites and satellite pegmatites and aplites, as well as Oligocene-Miocene plutonic, subvolcanic and volcanic rocks that are variably hydrothermally altered and mineralized, outcrop in the broader region. The mineralization appears as veins, discordant lodes and disseminations. Veins and discordant lodes exhibit massive and brecciated textures. Historic underground mining (1930s–1950s) produced 9000 t of stibnite ore, grading 40% Sb on average. The main ore mineral assemblage includes stibnite + berthierite + sphalerite + pyrite + chalcopyrite + native antimony and traces of wolframite, galena, tetrahedrite, marcasite, pyrrhotite, arsenopyrite, realgar, native arsenic and native gold. Quartz, minor barite and ankerite are the gangue minerals. Sericitization and silicification developed along the shear-zone, forming hydrothermal halos of moderate intensity in the two-mica gneiss. Locally, valentinite, goethite and claudetite are present due to the supergene oxidation of the stibnite mineralization. Bulk ore geochemistry shows enrichments in specific elements including As, Au, Cd, Se, Tl and W. Fluid inclusion microthermometry showed that the mineralization was formed under a limited range of temperatures and salinities. The fluids had low to slightly moderate salinities (6.6–8.1 wt% equiv. NaCl) with low homogenization temperatures (217–254 °C, with a maximum at 220 °C). [ABSTRACT FROM AUTHOR]

The Jagpura Au-Cu deposit is situated within the Aravalli craton in the northwestern part of India. In the present work, petrography, mineral chemistry, fluid inclusion and sulfur isotopic compositions were used to study the Jagpura Au-Cu deposit. The ore mineral association of the deposit is arsenopyrite, loellingite, chalcopyrite, pyrrhotite and pyrite, along with native gold, magnetite and apatite. The gold fineness ranges from 914–937‰ (avg. 927‰). The presence of Au-Bi-Te phases, pyrite (>1 Co/Ni ratio), magnetite (≥1 Ni/Cr ratio, <1 Co/Ni ratio) and apatite (>1 F/Cl ratio) suggest the hydrothermal origin Au-Cu mineralization. A fluid inclusion study indicates the different episodes of fluid immiscibility with the homogenization temperatures varying between 120–258 °C and salinities range within the 8.86–28.15 wt% NaCl eq. The sulfur isotopic composition of sulfides varies from 8.98 to 14.58‰ (avg. 11.16‰). It is inferred that the variation in the sulfur isotopic compositions of sulfides is due to the cooling and dilution of the metalliferous fluid of mixed origin, derived from the basement meta-sedimentary rocks and the high saline basinal fluid. The iron oxide-copper-gold-apatite associations, structural control of mineralization, pervasive hydrothermal alteration, fluid salinity and sulfur isotope compositions indicate that the Jagpura Au-Cu deposit is similar to the iron oxide-copper-gold (IOCG)-iron oxide-apatite (IOA)types of deposits. Based on the ore geochemistry and the trace elements systematic of magnetite, the deposit is further classified as an IOCG-IOA type: IOCG-Co (reduced) subtype. [ABSTRACT FROM AUTHOR]

Arsenic (As) migration and transformation in the supergene environment and eucalyptus planting have essential effects on ecology or even human health, respectively. However, the combined environmental impact of As migration and transformation and eucalyptus planting has not been studied. Here we report a case of soil As contamination caused by eucalyptus planting and address the fate of As in Longmen county, Guangdong Province, China. We found high As content in weathered arsenopyrite bearing granite or granite-derived soil, where a large area of eucalyptus is planted. The release of organic acids from eucalyptus roots promoted the electrochemical reaction of arsenopyrite to produce AsO33−. In the subsequent supergene migration process, As species change from arsenite to arsenate with the addition of oxygen and the effect of clay minerals, last with As infiltration, precipitation, and enrichment, forming the As contamination in soil. The whole process reveals the activation process of eucalyptus to the As source (arsenopyrite), the migration and transformation process of As in the supergene environment, and the formation mechanism of soil As contamination. This finding provides a new perspective of soil As contamination around arsenopyrite bearing granite of the Nanling area with eucalyptus planting and proposes that the negative effects of Nanling eucalyptus planting may be greater than expected. [ABSTRACT FROM AUTHOR]

The Paleoproterozoic Svecofennian Central Finland Granitoid Complex (CFGC) has been regarded as an area of low mineralisation potential. The Hiekkapohja area, 20 km north-east of the town of Jyväskylä, host a concentration of variable metalliferous showings. Samples from mineralised boulders and outcrops display variable combinations of anomalously high concentrations of Cu, Mo, Zn, Pb, W, Pb, Ag, As, and Au. The area is composed mainly of peraluminous and ferroan granitoids. The dominant porphyritic Hiekkapohja granodiorite (~1.88 Ga) is cross-cut by the equigranular Soimavuori granite of similar age. The porphyritic Lehesvuori granite on the western side of the study area represents marginally older (~1.89 Ga) magmatism. The paragenetic sequence of the ore minerals shows that the Hiekkapohja area has been affected by at least two separate stages of hydrothermal activity. The first mineralisation stage was widespread, crystallising typically chalcopyrite, pyrrhotite, sphalerite, galena, arsenopyrite, magnetite and Ag-bearing minerals. After the first stage, a low temperature oxidising phase formed hematite and marcasite. The second mineralisation stage enclosed low temperature minerals, such as marcasite and native Ag and Ag-minerals, as inclusions inside chalcopyrite, pyrite, pyrrhotite, sphalerite, and arsenopyrite. The mineralised samples typically display signs of K-metasomatism and less commonly signs of propylitic alteration. During the second mineralisation stage the fluid flow was controlled by the dominant 120°-135° trending shear zones. Both the hydrothermal activity and the regional geology indicate that porphyry type ore forming processes have occurred in the Hiekkapohja area. Paleoproterozoic resetting of the remanent magnetisation is further evidence for the role of the hydrothermal system. [ABSTRACT FROM AUTHOR]

The Hamzeh–Gharanin gold deposit (HGD) is located in the Qolqoleh–Kasnazan shear zone in the northwest of Sanandaj–Sirjan Zone (SSZ) and 40 km SW of Saqez. The main rock units are an assemblage of the Precambrian metasedimentary (pelitic) rocks and the Cretaceous phyllite associated with marble interlayers. The post–Cretaceous intrusive granitoids with NW–SE trends intruded within these two units. Mineralization occurs mainly within the NE–SW extensional veines and veinlets in proto–mylonitic, mylonitic and ultra–mylonitic rocks. Hydrothermal alterations consist of sericitization, carbonatization, silicification and chloritization. The main ore minerals include pyrite, chalcopyrite, arsenopyrite, pyrrhotite, sphalerite, galena, gold, magnetite and hematite. The fluid inclusions study from quartz minerals associated with the mineralization shows four different phases: single vapor phase (V; type I), single liquid phase (L; type II), liquid–vapor biphasic (LV; type III) and three phases (LLV; type IV). Microthermometric studies were performed on types III and IV of fluid inclusions. Homogenization temperatures (Th) for Types III and IV inclusions vary between 138 and 310 °C (mean 230 °C) and 250–335 °C (mean 300 °C) and their salinity varies between 0.52 and 13.87 and 4.79 to 9.58 (wt% NaCl), respectively. Moreover, the density of Types III and IV inclusions vary from 0.71 to 0.927 g/cm3 and 0.700–0.870 g/cm3, respectively. The oxygen (in quartz: 4.58–7.80 ‰; mean 5.82 ‰) and δ34S (in pyrite: 5.54–6.28 ‰; mean 5.91‰) isotope compositions of the mineralizing fluids indicate an insignificant meteoric water input during hydrothermal evolution and a magmatic origin of sulfur in the deposit which is broadly similar to those of orogenic gold deposits worldwide. [Display omitted] • This study presents the metallogenic processes and ore-forming fluids evolution in the Hamzeh–Gharanin Au deposit. • The deposit was formed during the continental collision in the shear zone. • The main characteristics of geology and mineralization are similar to orogenic gold deposits. [ABSTRACT FROM AUTHOR]

The medium-sized Daping gold deposit is located in the middle Xuefeng Mountain area of Southern China with gold ores hosted in sericite phyllite, sericitolite, and mylonite. The auriferous quartz-carbonate-sulfide veins and adjacent alteration rocks are structurally controlled within the NE (northeast) shear zone with NE, NNE (north-east-east), and NW (northwest) trending at high inclination angles. The petrogeochemistry analysis results show that the gold ores are characterized by high content values of SiO2, S, and As and low content values of Al2O3 and Na2O and display strong enrichment of LREE with δEu values ranging from 0.54 to 0.75. Four stages of mineralization/alteration were identified: the first stage has mineral assemblages of quartz+pyrite+arsenopyrite±carbonate minerals, the second stage has mineral assemblages of quartz+polymetallic sulfide minerals (pyrite, arsenopyrite, chalcocite, galena, chalcopyrite, tetrahedrite)±chlorite±carbonate minerals, the third stage has mineral assemblages of quartz and carbonate minerals, and the supergene stage is characterized by limonite±patina which were formed by the oxidation of metal sulfides. Among them, the first stage and the second stage are the main gold mineralization stages. The ore-forming fluid inclusions in quartz are mainly composed of liquid phase (H2O) and gas phase (H2O and CO2), and based on the microthermometric analysis, the first metallogenic stage and second metallogenic stage yielded average homogenization temperature of 184.5 and 255.8°C and average salinity of 7.64 wt.% NaCl eqv. and 11.35 wt.% NaCl eqv., respectively. Thus, the ore-forming fluids belong to H2O-CO2-NaCl, medium-low temperature, and medium-low salinity fluid. The δ D H 2 O and δ 18 O H 2 O values of auriferous quartz are from -51‰ to 62‰ and from -1.44‰ to 5.42‰, respectively, indicating that the ore-forming fluids may belong to mixing fluids of the magmatic fluid and meteoric hydrothermal fluid. The values of δ34S of metal sulfides range from -0.94‰ to 1.98‰ (-0.131‰ in average), implying that sulfur may source from the concealed granite and/or basement metamorphic strata. The Daping gold deposit formed in the Indosinian period under the tectonic environment of compression between the Cathaysian plate and Yangtze plate and may belong to orogenic gold deposits. [ABSTRACT FROM AUTHOR]

The Shenshuitan gold deposit is located within the Eastern Kunlun Orogen in northwest China. The gold mineralization here occurs primarily within the ductile fault XI. The sulfide mineral assemblage is dominated by pyrite and arsenopyrite, with minor pyrrhotite, chalcopyrite, galena, and sphalerite. Host rocks predominantly consist of Ordovician silicic slate and late Silurian granites, and their alterations include silicification and sericitization. The measured δD and δ18O values of quartz and sericite range from −113.9‰ to −93.1‰ and from 4.6‰ to 12.0‰, respectively. Bulk and in situ δ34S values of sulfides range from −7.3‰ to +9.6‰ and from −3.92‰ to 11.04‰, respectively. Lead isotope compositions of sulfides show 206Pb/204Pb ratios from 18.071 to 19.341, 207Pb/204Pb ratios from 15.530 to 15.67, and 208Pb/204Pb ratios from 37.908 to 38.702. Collectively, the isotope (H, O, S, and Pb) geochemistry suggests that the ore-forming fluids were of a metamorphic origin mixed with meteoric water and that the sulfur and lead were sourced from a mixture of host rocks and original ore-forming metamorphic fluids. Lastly, this deposit can be classified as an orogenic gold deposit associated with the final collision between the Bayan Har–Songpanganzi Terrane and the Eastern Kunlun Orogen during the Later Triassic. [ABSTRACT FROM AUTHOR]

Although forming one unified class, orogenic gold deposits may be associated with a range of ore mineral assemblages controlled by a variety of gold deposition processes that have a direct impact on gold grade. Whereas, a better understanding of the deposition process may be critical for effective targeting of highly-endowed gold deposits, it is challenging to establish a direct comparison between mineral systems formed under different conditions. Accordingly our ability to predict whether contrasted mineral associations may be more or less prospective for high grade mineralization remains poor. In this paper, we compare fluid-rock interaction processes that led to the coeval formation of two contrasting gold mineral assemblages within the world-class Callie orogenic gold deposit. Stratabound and vein-hosted lodes formed within the same structural framework but with contrasting grades (∼3 g/t Au and ∼8 g/t Au, respectively). The stratabound mineralization consists of bedding-parallel sulfides in which gold is preserved in arsenopyrite micro-fractures. The vein-hosted mineralization consists of locally very high-grade (up to 10,000 ppm Au) visible gold concentrated in quartz veins. Both mineralization styles are hosted within different metasedimentary stratigraphic horizons with contrasting compositions. The stratabound mineralization occurs in iron-oxide rich siltstones whereas the vein-hosted mineralization occurs in carbonaceous siltstones. We investigate the fluid-rock interaction mechanisms of the two styles of mineralization at the Callie deposit by combining petrographic observation with whole-rock geochemistry, quantitative chlorite and gold analyses and thermodynamic modeling. Our results show that the stratabound mineralization occurred in response to sulfidation of the host-rock whereas decarbonation alteration, associated with the vein-hosted mineralization, records oxidation of the host-rock. Our investigation shows that gold deposition induced by oxidation of the host-rock produces the valuable, locally very-high grade visible gold mineralization whereas the sulfidation process lead to the formation of lower grade gold mineralization disseminated within the sulphide ore assemblage. We conclude that the nature of the host-rock applies a first-order control on the gold deposition efficiency in metasedimentary-hosted gold deposits. [ABSTRACT FROM AUTHOR]

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

The Vathi porphyry Cu-Au ± Mo mineralization is located in the Serbo-Macedonian metallogenic province of the Western Tethyan Metallogenic Belt. It is mainly hosted by a latite and is genetically associated with a quartz monzonite intrusion, which intruded the basement rocks of the Vertiskos Unit and the latite, 18 to 17 Ma ago. A phreatic breccia crosscuts the latite. The quartz monzonite was affected by potassic alteration, whereas the latite was subjected to local propylitic alteration. Both styles of alteration were subsequently overprinted by intense sericitic alteration. M-type and A-type veins are spatially associated with potassic alteration, whereas D-type veins are related to the sericitic alteration. Three ore assemblages are associated with the porphyry stage: (1) pyrite + chalcopyrite + bornite + molybdenite + magnetite associated with potassic alteration; (2) pyrite + chalcopyrite related to propylitic alteration; and (3) pyrite + chalcopyrite + native gold ± tetradymite associated with sericitic alteration. A fourth assemblage consisting of sphalerite + galena + arsenopyrite + pyrrhotite + pyrite ± stibnite ± tennantite is related to an epithermal overprint. Fluid inclusion data indicate that the A-type veins and related porphyry-style mineralization formed at 390–540 °C and pressures of up to 646 bars (<2.6 km depth) from boiling hydrothermal fluids. A later condensation of vapor-rich inclusions resulted in a moderately saline fluid (8.4–11.2 wt % NaCl equiv) at temperatures between 311 and 392 °C, which were related to sericitic alteration, D-type veins, and associated metallic mineralization. Subsequent dilution of the moderately saline fluid at lower temperatures (205–259 °C) produced a less saline (1.4–2.9 wt % NaCl equiv.) fluid, which is likely associated with the late epithermal overprint. [ABSTRACT FROM AUTHOR]

Gold‐silver deposits in the Atalla area occur as hydrothermal quartz veins in NE–SW pre‐existing fractures within the Atalla granitic pluton. The orientation of such quartz veins has been attributed to extensional behavior related to the Atalla Shear Zone (ASZ). The Atalla area is covered by a variety of lithologies that are (from oldest to youngest): metasedimentary rocks, metavolcanic rocks, ophiolite assemblage (serpentinites/talc‐carbonates), Atalla granite and Dokhan volcanic rocks. Microscopically, Atalla granite ranges in composition from granodiorite to monzogranite. Whole‐rock geochemistry constrains the calc‐alkaine affinity of the Atalla granite that was intruded within an orogenic (syncollision) tectonic regime. The ore minerals are represented by gold/silver (electrum), pyrite (Py1 & Py2), arsenopyrite, pyrrhotite, sphalerite, chalcopyrite, galena, covellite and goethite. The temperature of ore formation ranges from 240 to 285°C and the estimated fluid pressure is in the range of 20–100 MPa. Based on the geological setting, ore textures and fluid characteristics; the Atalla Au‐Ag deposits are considered to be orogenic in nature, formed from a continental collision (∼653‐590 Ma), synchronous with the emplacement of calc‐alkaline magmatism during the evolutionary history of the Arabian Nubian Shield (ANS). The initial ore‐forming fluid was primarily derived from a metamorphic source related to ophiolitic‐serpentinite rocks under deep regional conditions of greenschist‐amphibolite facies, where the Atalla granitic eruption provided the required temperature conditions for the metamorphic process to take place. Under such conditions, the transportation of ore metals as bisulfide complexes is favoured. The deposition of ore minerals was triggered by fluid‐wallrock interaction through fracture pathways in conjunction with a temperature‐pressure drop that is likely to have been related to uplift into the crustal levels. [ABSTRACT FROM AUTHOR]

In geochemistry, the elevated concentrations of certain elements in rock or mineral samples are used for the assessment of a mineralising system's important geological characteristics. The relationship between the elements and system characteristics may take one of two forms, regression or classification. The collection and analysis of geochemical samples typically leads to the development of sparse and fuzzy multivariate datasets, which often have complex interrelationships. As a result, it is difficult to quantitatively and qualitatively interpret many of these geochemical datasets and relate the resulting data to relevant geological characteristics. There are no governing expressions in the current literature that can relate mineral-based trace element assemblages to geological characteristics. In this work, a generalised formulation for multivariate systems modelling is presented and it is applied to the discovery of the manifested system characteristics of arsenopyrite samples collected from Australian gold (Au) deposits, using fuzzy arsenopyrite trace element datasets. Arsenopyrite trace element assemblages, collected using laser ablation-inductively coupled plasma-mass spectrometry, are represented as spatially distributed networks embedded in R 4 , 1 conformal geometric algebraic space. The interactions of elements within these networks generate multivectors which are referred to as hyperfields. The functions and parameters used to generate these hyperfields are optimised to create multiple unique models, which are used to discover relationships between system characteristics and the multivariate dataset. The models generated allow a specialist to discover qualitative relations, using higher-dimensional representations of multivariate data. In this work, the generalised hyperfield formulation is applied to the problem of predicting the endowment, lithology and camp of Au deposits, using an arsenopyrite trace element dataset. The hyperfield formulation is compared against the state-of-the-art random forest decision tree algorithm 'XGBoost' and artificial neural networks (ANNs). [ABSTRACT FROM AUTHOR]

The Churan gold and copper deposit located 70 km northeast of Sirjan in the Dehaj- Sarduyeh structural subzone of the Urumieh -Dokhtar magmatic arc. Lithologically, the area mainly consists of the Middle Eocene volcanic rocks with dominant andesite to andesite-basalt crosscutting by the intrusive rocks and quartz dioritic to granodioritic dykes belonging to the Oligocene-Miocene time. The host granitoid rocks are classified as meta-aluminous I-type granitoid with high potassium calc-alkaline affinity dominated by plagioclase, biotite, hornblende, alkali feldspar, quartz and apatite, zircon, and opaque as accessory minerals. The rocks under study are characterized by large ion lithophile element (LILE) enrichment, high field strength element (HFSE) depletion, and high LREE/HREE ratios. On tectonomagmatic discrimination diagrams, the Churun granitoids are scattered on active continental margins to post-collisional fields. Mineralization occurred as gold and copper-bearing quartz vein and veinlets in the quartz diorite intrusive. Hydrothermal alterations associated with the mineralization contain silicification, sulfidation, tourmalinization, and sericitization. Ore mineral assemblages in the deposit consist of pyrite, arsenopyrite, chalcopyrite, bornite, sphalerite, galena, covellite, malachite, and iron hydroxides. The mineralization criteria as well as the spatial relationship between ore-bearing veins and alteration zones granite-granodiorite intrusion suggest that gold mineralization in the investigated area is related to granite-granodiorite emplacement and likely originated from those rocks. [ABSTRACT FROM AUTHOR]

The Xin'gaguo deposit is representative of the skarn Pb–Zn polymetallic zone in the northern Gangdese porphyry metallogenic belt, Tibet. Pb–Zn mineralization is hosted in the Take'na formation skarn. The Xin'gaguo ore‐forming process can be divided into prograde skarn, retrograde skarn and quartz‐sulfides. Skarn minerals include garnet, diopside, and epidote, with minor wollastonite, actinolite, and chlorite. Metallic minerals are mainly sphalerite, galena, chalcopyrite, magnetite, and pyrrhotite, with minor arsenopyrite, marcasite, native bismuth, cosalite, and gersdorffite. The LA–ICP–MS zircon U–Pb age of the diorite is 59.66±0.52 Ma. Diorite samples are characterized by fractioned REE patterns with marked positive Eu anomalies, enriched LILEs (Rb, Ba, Th, U, and K) and depleted HFSEs (Ta, Nb, Zr, Hf, and Ti), belong to the calc‐alkaline series and have metaluminous compositions. Zircon εHf(t) values of the diorite are positive (5.7–11) and lie between the chondrite and mantle values. These geochemical characteristics suggest that the diorite was formed by the partial melting of a young metasomatized asthenospheric mantle wedge deriving basaltic rocks. The δ34S values of sulfides range from −4.7 to 4.5‰ and show a bimodal distribution, indicating interactions of magma‐derived ore fluid with biogenic sulfide minerals from the Take'na formation. The 206Pb/204Pb (18.5–18.629), 207Pb/204Pb (15.599–15.704), and 208Pb/204Pb (38.616–38.975) of sulfides show that ore‐forming metals were derived from mixed sources, in part from the Lhasa Terrane basement. Skarn mineral compositions imply that the ore‐forming environment was variable, and underwent at least three changes in oxidation‐reduction state. The geochemical characteristics of diorite indicate that the Xin'gaguo deposit formed within the Indo‐Asian continental collision tectonic setting. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Laguhe deposit is classified as a Carlin-like type gold deposit. • The main ore-forming temperatures are constrained at 320–370 °C. • The Au(HS) 2 – and AuH 3 SiO 4 are the Au main migrated forms in hydrothermal fluids. The precious metal Au has a wide range of utilization in various fields, and the Au deposits in China are hosted mostly within the West Qinling Orogen and Jiaodong Peninsula. The Laguhe deposit is a newly discovered medium–size Au deposit in the West Qinling Orogen. Previous studies focused mainly on the nature of Au mineralization in this deposit during different exploration stages, so its genesis and ore–forming physico–chemical conditions and processes remain enigmatic. Here, we present major and trace element analyses of Au–bearing pyrite and arsenopyrite from the Laguhe Au deposit, in combination with machine learning to explore its origin and ore–forming processes. The early and late stages of arsenopyrite show As contents of 40.69–46.22 wt% and 39.12–43.22 wt%, respectively, which constrain corresponding ore–forming temperatures at 320–370 °C and 270–340 °C, respectively. The sulfur fugacities in the two stages range from 10–13.2 to 10–8.4. The arsenopyrite has high Co and Ni contents of 0.02–0.28 wt% and 0.02–0.27 wt%, respectively, which suggest that a deep source mafic magmatic water participated in the Au mineralization. The Fe/(S + As) ratios in pyrite vary from 0.838 to 0.869, which indicate that the Laguhe deposit formed at a moderate to deep ore–forming depth (1.5–8.0 km). Most of the Co/Ni ratios (1–5) and the negative correlation (–0.47) between Fe and As contents in pyrite suggest that the ore–forming hydrothermal fluids in the Laguhe deposit were moderately acidic. Based on the heterogeneous Au contents and the lack of correlation between Fe and Au in pyrite and arsenopyrite, most of Au are suggested to likely exist as nanoparticles, with few as lattice Au in pyrite and arsenopyrite. Machine learning results based on the geochemistry of arsenopyrite and pyrite and geochemical features of arsenopyrite and pyrite classified the Laguhe deposit as a Carlin–like type Au deposit. The Au in the Laguhe deposit migrated mainly in the forms of Au(HS) 2 – and AuH 3 SiO 4 in hydrothermal fluids, which then precipitated as a result of water–rock reaction, fluid immiscibility and fluid boiling at and around plutons and along faults. [ABSTRACT FROM AUTHOR]

The Zaozigou gold deposit lies in the West Qinling orogenic belt, Gansu Province, China. It is one of the largest gold deposits, and the orebodies are hosted in fine‐grained slates intercalated with limestone of the Middle‐Triassic Gulangdi Formation and varied dykes. The gold orebodies are strictly controlled by the NE‐, NW‐, and SN‐trending tensional and shearing faults with high dipping angle. The mineralogy and geochemistry of pyrite and arsenopyrite are measured by electron microprobe. Pyrite has up to 0.12 wt.% Au, and arsenopyrite contains up to 0.17 wt.% Au. The antithetic correlation between S and As indicates the substitution of As for S in pyrite, and arsenic occurs in anionic As1− state in the pyrite structure under the reduced conditions. Pyrite has relatively high Co (~364–2248 ppm) but relatively low Ni (~109–497 ppm) contents, with Co/Ni ratios ranging from ~1.63 to 10.50, indicating that the deposit originated from a volcanogenic fluid and remobilized by hydrothermal fluid. Au in arsenopyrite occurs as cationic Au in solid solution, whereas Au in pyrite is in solid solution and metal nanoparticles (Au0). The texture characteristics and trace element geochemistry among cores, transition zones, and rims of pyrites demonstrate that there are at least four pulses of fluid participating in the generation of pyrite in the deposit. The calculated formation temperatures of the Zaozigou deposit vary from 148°C to 304°C, with an average temperature of 213°C based on Au contents in pyrite. The Pb isotopic compositions of pyrite samples suggest that the metallogenic materials of the Zaozigou deposit were derived from the mantle and upper crust. All the characteristics above lead us to draw the conclusion that the Zaozigou gold deposit is classified as an epithermal deposit. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • We document three auriferous veining stages at the Dublin Gulch RIRGS. • Gold Ag, Pb, and Bi were mobilized from arsenopyrite to form Au-P ± Bi mineral accumulations. • We suggest new Pb-Bi and Pb variations on the hydrothermal melt (Bi) collector model. Abstract Dublin Gulch reduced intrusion-related gold system (RIRGS), located in the Selwyn Basin area of western Canada, represents one of the best examples of RIRGS mineralization globally and hence can be studied to unravel genesis and evolution of these types of deposits. Based on textural relationships, mineralogy, and trace element mineral chemistry, three auriferous vein stages were identified. The paragenetic sequence for the auriferous vein stages are: 1) Eagle Style (ES), quartz-albite, low sulfide and sulfosalt content (<5% vol.), As-Fe-Mo-W-Pb-Bi-Au-Ag veins; 2) Potato Hills Style-1 (PHS-1), quartz, high sulfide and sulfosalt content (>30% vol.), As-Fe-W-Pb-Bi-Au-Ag veins; and, 3) Potato Hills Style-2 (PHS-2), high sulfide and sulfosalt content (>30% vol.), Fe-Pb-Sb-Zn-Cu-Au-Ag veins. In the ES and PHS-1 veins, Au is present both as native gold (Au, Ag) and as invisible gold in arsenopyrite, whilst in the PHS-2 veins, Au is present as invisible gold in pyrite. Native gold micrograins (individual grains, 1–100's µm in size) are observed associated with Pb minerals [in anhedral-to-globular cosalite (Pb 2 Bi 2 S 5) in ES veins, or galena (PbS) in the PHS-1 veins]. Native gold is also observed as micrograins along arsenopyrite margins and in quartz fractures. We suggest a variation on the hydrothermal Bi melt collector model to explain the Au-Pb ± Bi association. The Au, Ag, Pb, and Bi are interpreted to have been locally remobilized from arsenopyrite, which shows textures and trace element distribution patterns consistent with fluid-and-deformation assisted recrystallization. We suggest Pb and Bi were mobilized either as immiscible nanodroplets that coalesced to form larger Pb ± Bi liquid accumulations or into the hydrothermal fluid and subsequently exsolved to form immiscible Pb ± Bi liquids. We propose that remobilized Au and Ag were collected by these Pb+/-Bi immiscible liquids. Subsequent retrograde alteration (sulfidation) is interpreted to have converted the Au-Ag-Pb ± Bi alloys to native gold and cosalite (ES), and native gold and galena mineral assemblages (PHS-1). The similarity of the Au/Ag ratios in native gold and arsenopyrite supports a local source for the native gold micrograins. Temperatures required to attain liquid Pb 0.5 Bi 0.5 (>145.2 °C) and Pb (>327.5 °C), are consistent with arsenopyrite geothermometry (ES 345–405 °C; PHS-1 ≈ 380 °C). These suggested new variations (Pb-Bi and Pb) on the hydrothermal melt (Bi) collector model are important, given the common association of native gold with Pb ± Bi sulfosalts in many gold deposits, and the relatively low temperatures required to maintain these liquids and collect Au from the hydrothermal fluid. [ABSTRACT FROM AUTHOR]

This paper describes the Se proper minerals first identified in the primary ores in Uralian volcanogenic massive sulfide (VMS) deposits. The investigation was carried out by instrumental neutron activation analysis of bulk ore samples and the mineral monofractions and also by local analysis methods: LA-ICP-MS, electron microprobe analysis, and analytical electron microscopy. СSe reaches 977 ppm in the Uralian VMS ores. A significant positive correlation is characteristic for Se with Te, S, Fe, Co, Mo, Hg, and Bi. Se is concentrated in major sulfides, mainly in pyrite (73 ppm), chalcopyrite (49 ppm), and pyrrhotite (48 ppm). Sphalerite commonly contains <10 ppm Se. The Se content is high (up to 1–3 wt %) in secondary and rare minerals of the massive sulfide ores (mainly Pb, Te, and Bi compounds): tetradymite, galena, tellurobismuthite, altaite, and wittichenite. In the ores, the Se proper minerals occur as kawazulite, clausthalite, and galena–clausthalite Pb(Se,S), and also as micron inclusions with (Ag,Cu)2(Se,S); (Ag,Pb)3(Te,Se)S; and (Ag,Pb)2(S,Se) compositions. [ABSTRACT FROM AUTHOR]

Historical mining and mineral processing at the former Giant Mine (Yellowknife, NT, Canada) created an enduring legacy of arsenic (As) and antimony (Sb) contamination. Approximately 237,000 tonnes of arsenic trioxide roaster waste (ATRW) generated between 1948 and 1999 remains stored on-site in underground chambers. We studied the chemical forms and phase associations of As and Sb to improve understanding of ATRW environmental behavior. Although arsenolite [As 2 O 3 ] is the principal As and Sb host, we also observed minor associations of As with Fe oxides. Arsenic K-edge X-ray absorption spectroscopy (XAS) revealed As(III) dominated ATRW, with some As(V) and As(−I) also present. Arsenic coordination and bonding is consistent with arsenolite, while scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) showed minor As association with Fe oxides and arsenopyrite [FeAsS]. Antimony K-edge XAS revealed variable proportions of Sb(III) and Sb(V), with Sb−O, Sb−Sb and Sb−As bonding consistent with stibioclaudetite [AsSbO 3 ] or Sb-substituted arsenolite. Electron microprobe analysis (EMPA) results showed variable but quantitative Sb substitution for As in arsenolite grains, possibly influencing ATRW solubility and reactivity under environmental conditions. Overall, our results reveal complex As and Sb phase associations with important implications for ongoing remediation efforts and long-term environmental fate of ATRW solids. [Display omitted] • Arsenic trioxide roaster waste (ATRW) exhibits compositional heterogeneity. • Arsenic and antimony are principally associated with arsenic trioxide phases. • Antimony substitutes for arsenic in some arsenic trioxide crystals. • Iron oxides are minor arsenic and antimony hosts. • Complex phase associations may influence ATRW solubility and reactivity. [ABSTRACT FROM AUTHOR]

The Obří důl Fe-Cu-As polymetallic sulfide skarn deposit is developed in a metamorphic series in the West Sudetes, Bohemian Massif. It consists of lenses of marble, calc-silicate rocks, and skarns. We studied the Gustav orebody, which is located few hundred meters away from the contact with a large, late-orogenic Variscan Krkonoše-Jizera Plutonic Complex (KJPC) emplaced into shallow crust. Mineralogical and fluid inclusion study evidence indicates that the main sulfide stage, dominated by pyrrhotite, arsenopyrite, and chalcopyrite originated from aqueous hydrothermal fluids with salinity up to 8 wt% NaCl eq. with minimum homogenization temperatures ranging from 324 to 358 °C. These fluids mainly replaced carbonate-rich lithologies. Carbon, oxygen, and strontium isotope data in Ca-rich rocks imply total overprinting by channelized metasomatic fluid flow, which is most probably related to the intrusion of the KJPC, whereas δ34S values of sulfides argue for a magmatic source of sulfur. The Re-Os age of arsenopyrite overlaps published age data for the KJPC and suggests synchronous formation of the main sulfide mineralization and pluton emplacement. [ABSTRACT FROM AUTHOR]

The hydrothermal plume and the Si-Fe deposits is one of important sources and sinks of Fe and Si in the ocean, respectively. The Iron and Silica are concentrated on the seafloor through two basic processes: abiogenic and biogenic ways. For the abiogenic process (a), the iron and silica within the plume partly form the mixed colloidal phase which precipitates as amorphous oxide and oxyhydroxide on the seafloor. While, for the biogenic process (b), the Si and Fe were consolidated into the Si-Fe deposits through the biologically induced mineralization or/and biologically controlled mineralization. While the exact mechanism of Si-Fe deposits from Jiawang Seamount remain unsolved. [Display omitted] • New Geophysical and seafloor imaging data around Jiawang Seamount were recovered. • Jiawang ferromanganese deposits primarily consist of amorphous Fe-Si oxyhydroxide. • One mixed mechanism (Hydrothermalism and biogenesis) was proposed. The Jiawang Seamount is a young volcanic edifice in the central Bransfield Basin, Antarctica. Ferromanganese precipitates were collected from its top during the R/V "Xianghong 01" cruise during the austral summer season of 2017/2018. The mineralogical and chemical compositions of typical species were analyzed to decipher their origin. These ferromanganese fragments were very light in weight and characterized by channel/cavity structures. Their mineralogy was mainly amorphous Fe-Si oxyhydroxide, with minor amounts of pyrite, arsenopyrite and metal compounds. Geochemically, they were enriched in Fe and Si and depleted of Mn, with Mn/Fe ratios of approximately 0.009. Most trace elements were depleted in these species, but Mo and Ge were enriched relative to the elemental contents of the upper continental crust. Additionally, these samples were depleted in rare earth elements, with an average of 77.64 μg/g. The post-Archean Australian shale (PAAS)-normalized rare earth element (REE) patterns showed negative Eu anomalies but no Ce anomalies. Biomorphic-like structures were present in the samples, probably indicating that bacteria such as Leptothrix ochracea, Gallionella ferruginea and Mariprofundus ferrooxydans had, to some extent, affected sample formation. All of these facts also indicated that one mixing process (hydrothermal process and biological process) affected the ferromanganese deposits in the Bransfield Basin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Gold and As contents in pyrite from Carlin-type Au deposits may be coupled or decoupled. • High As contents in pyrite favor Au incorporation, but are not solely responsible for Au enrichment. • The variable evolution of ore-forming fluids in the Youjiang Basin led to the various relationships of Au and As in pyrite. • Gold precipitation was controlled by the extrinsic fluid conditions and microscopic reactions at the fluid–mineral interface. The low-temperature geochemistry of gold (Au) and arsenic (As) in pyrite from Carlin-type Au deposits is significant for understanding the enrichment mechanisms of Au in pyrite, but remains poorly understood due to the complex processes that lead to the precipitation of micron-scale pyrite grains. This paper concerns the geochemical behaviors of Au and As during the precipitation of pyrite from six Carlin-type Au deposits (the Nibao, Shuiyindong, Banqi, Jinya, Yata, and Zimudang deposits), southwest China. These deposits are located in different locations and ore-bearing horizons of the Youjiang Basin. Arsenian pyrite and/or arsenopyrite are the dominant Au-bearing minerals. Gold-bearing pyrite grains are typically zoned (core, intermediate, and rim), with multiple, oscillatory banded sub-zones. In situ analysis demonstrates that invisible Au exists mainly as cationic Au+ in the growth zones of pyrite. Gold and As are positively correlated (i.e., coupled) in the Nibao and Shuiyindong deposits, negatively correlated in the Banqi, Jinya, and Yata deposits, and poorly correlated in the Zimudang deposit. Arsenic and S substitution in pyrite and the presence of a reduced fluid promoted the incorporation of Au, resulting in the coupling of Au and As. The Au precipitation was affected by changes in the physicochemical conditions of the hydrothermal systems, independent of the As concentration, resulting in decoupling of Au and As. As such, invisible Au precipitation is controlled by the extrinsic physicochemical conditions of the ore-forming fluids and microscopic reactions at the fluid–mineral interface, and also the episodic incursion of Au-rich hydrothermal fluids. High As contents in pyrite favor Au incorporation, but are not solely responsible for Au enrichment. Gold and As contents in pyrite in Carlin-type Au deposits may be coupled or decoupled. [ABSTRACT FROM AUTHOR]

The Jinji deposit is the first reported gold deposit with a genetic link to early Paleozoic granitic magma, and this gold mineralization style in northeastern Hunan should be paid more attention in future exploration work. [Display omitted] • The Jinji Au deposit in middle Jiangnan Orogen (South China) has three ore stages. • H-O-S-Pb isotope data suggest ore-material were derived from granitic magma. • The Jinji is orogenic type and linked to Early Paleozoic syn -collisional magmatism. The Jinji gold deposit (northeastern Hunan province) is located in the central Jiangnan Orogenic Belt, South China. The auriferous sulfide-calcite-quartz vein orebodies, controlled by near NNW-trending faults, occur in the Lengjiaxi Group metamorphic rocks spatially associated with the Banshanpu granitic pluton. Metallic minerals include mainly pyrite, arsenopyrite, and pyrrhotite, with minor sphalerite, chalcopyrite, galena, and native gold. The main alteration types include K-feldspar, silicic, sericite, carbonate, and chlorite. The gold mineralization comprises three stages: (1) quartz–K-feldspar–chlorite–carbonate–arsenopyrite–pyrite, (2) quartz–carbonate–chlorite–polymetallic, and (3) quartz–carbonate–fluorite–pyrite. Geothermometry of chlorite yielded formation temperatures of 261–332 °C (stage 1) and 262–290 °C (stage 2), whereas the calculated oxygen fugacity of chlorite is −45 to −40 (stage 1) and −42 to −39 (stage 2). The δ18O H2O and δD values are 8.8–10.5 ‰ and −73.3 to −72.8‰ (stage 1), 3.2–4.8 ‰ and −83.6 to −80.7‰ (stage 2), and −1.4 to −0.4 ‰ and −82.2 to −78.6‰ (stage 3), respectively. These results indicate that the primary ore fluids (stages 1 and 2) were derived from a granitic magma and were mixed with meteoric water in stage 3. The gold-bearing sulfides (pyrite, pyrrhotite and galena) have δ34S values of −4.8 to +5.8‰, whilst their 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios are of 35.975–36.204, 15.160–15.231, and 16.100–16.176, respectively. The sulfide S-Pb isotope compositions indicate that the metals were likely derived from the Banshanpu granitic magma, which was produced by partial melting caused by Early Paleozoic crustal thickening. The Jinji deposit exhibits many features of orogenic gold mineralization, such as the ore-controlling structures and mineralization styles (quartz-calcite-sulfide veins). The Jinji deposit is the first reported gold deposit in the central Jiangnan orogen with a genetic link to early Paleozoic granitic magma. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mineralization is in quartz veins (W-Sn) and granitoid breccias (Sn). • W-Sn mineralization related to H 2 O–NaCl magmatic-hydrothermal fluids. • Sulfides related to H 2 O–CO 2 –CH 4 –N 2 –NaCl fluids. • Several processes could have triggered mineral deposition. The Peña do Seo W-Sn ore deposit in NW Iberia consists mainly of quartz veins hosted in schists. Vein mineralogy comprises wolframite, cassiterite and minor molybdenite. Peraluminous S-type granites and minor metaluminous granitoid breccias crop out in the same location. Whole rock geochemistry, mineral characterization, fluid inclusions and stable isotope geochemistry have been combined to infer hydrothermal mineralization conditions. A pre-ore stage (0) involving the alteration of host rocks, three stages of mineralization (I, II and III), and a supergene stage (IV) have been identified. Stage I (oxide-halide-sulfide stage) consisted of a cassiterite-pyrite-fluorite mineralization in granitoid breccias. Stage II (main oxide stage) involved wolframite-rich selvages and wolframite-cassiterite-(molybdenite) quartz veins. Stage III (main sulfide stage) consisted of a sulfide mineralization in quartz veins comprising pyrite and minor arsenopyrite and chalcopyrite. Three types of fluid inclusions were found in vein quartz: (1) aqueous two-phase inclusions, with homogenization temperatures (Th) between 445 °C and 280 °C and moderate salinities (9–14 wt% NaCl eq.), (2) aqueous-carbonic three-phase fluid inclusions, with Th from 340 °C to 260 °C and low salinities (2–7 wt% NaCl eq.), and (3) aqueous two-phase fluid inclusions, with Th from 270 °C to 155 °C and low salinities (0–6 wt% NaCl eq.). δ18O values in quartz from mineralized veins range from +11.2‰ to +13.4‰, and between +15.0‰ and +15.4% in quartz from mineralized granitoid breccias. δ34S values in sulfides (pyrite, arsenopyrite and chalcopyrite) range between +13.0 ‰ and +37.1 ‰, thus suggesting a marine source of sulfate and possible equilibration with host-rock sulfides. δD values in muscovite and chlorite from quartz veins range between −105.7 ‰ and −71.5 ‰ and between −69.4 ‰ and −67.1 ‰, respectively, indicating a transition from magmatic to magmatic-metamorphic conditions. An aqueous (H 2 O–NaCl) magmatic-hydrothermal fluid led to the W-Sn mineralization, as deduced from the studied fluid inclusions and isotopic signatures. High W and Sn contents in the peraluminous granites indicate that the W-Sn mineralization in Peña do Seo could partially be related to the granites and granitoid breccias. Whereas the Sn (±W) likely derived from hydrothermal fluids exsolving from the crystallizing magmas, host quartz schists would have supplied other elements required for wolframite deposition such as Fe and Mn. Sulfide mineralization in stage III was probably driven by fluid dilution. [ABSTRACT FROM AUTHOR]

[Display omitted] • The independent selenides coexisting with tellurides and sulfides were discovered for the first time in the Zhaishang gold deposit. • The ore-forming materials leached from the underlying Paleozoic strata, and were affected by Indosinian magmatism. • The mineral paragenetic association shows that the redox conditions have changed from reduction to oxidation during the fluid evolution process. • The sulfur, tellurium and selenium fugacity of hydrothermal fluid of the main metallogenic stage is estimated in this paper. The Zhaishang gold deposit is characterized by Au–Sb–W paragenetic association, hosted in the Middle Devonian strata and Lower Permian strata of the Western Qinling Orogen, Central China; also found in in the mining area is a small carbonatized diorite porphyrite. Besides common sulfides, such as pyrite, arsenopyrite and chalcopyrite, some specific telluride and selenide minerals were found, and especially the first discovery of independent selenides. The assemblage pyrrhotite–arsenianpyrite–arsenopyrite suggests a relatively reducing environment for mineralization during stage II. However, the occurrence of selenides (clausthalite, tiemannite) and sulfates (barite and gypsum) represents a change of redox conditions from reduction to oxidation in stage III. On this basis, combined with the study of fluid inclusions and thermodynamic data, we evaluated the physicochemical conditions of the main metallogenic stages. the sulfur fugacity (log f S 2) did not change significantly from stage II to stage III, the selenium fugacity (log f Se 2) values were constrained to have been ≤ -13.7 in stage II, ranged from −14.8 to −9.8 in stage III, and the tellurium fugacity (log f Te 2) ranged from −14.0 to −11.2 in stage III. Moreover, the He–Ar–Pb isotopic values of sulfides suggest that ore-forming materials were dominantly of stratigraphic source but with important additions of magmatically derived hydrothermal fluid during Indosinian period. Water-rock reaction and ore-forming fluid mixed with magmatically-derived hydrothermal fluid were likely the dominant mechanisms of precipitation. Meanwhile, boiling likely played a certain role in the deposition of selenides and tellurides. [ABSTRACT FROM AUTHOR]