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[Display omitted] • Pyrite and pyrrhotite reveal homogeneous textures with some micro-inclusions. • Pyrite and pyrrhotite are enriched in Co, Ni, Cu, Pb, Zn, Ag, Bi, Mn, As, Se, and Sb. • The variation of Co, Ni, and Co/Ni ratios is linked with the distance to ore-related granite. • In-situ sulfur isotopes demonstrate a magmatic source for ore-forming materials. • The formation of Ag–Pb–Zn veins are due to a decrease of temperature, salinities, f S 2 and f O 2. Xiasai is the largest magmatic-hydrothermal Ag–Pb–Zn–Sn deposit in the central Yidun Terrane (SW China). Two generations of pyrite are associated with Ag–Pb–Zn mineralization. The coarse-grained pyrite (PyI) occurs together with arsenopyrite and pyrrhotite, and the fine-grained pyrite (PyII) is associated with sphalerite and chalcopyrite. This study documents LA-ICPMS mapping, trace element and LA-MC-ICPMS sulfur isotopic analyses of the two types of pyrite and pyrrhotite, to further constrain the formation of Ag–Pb–Zn veins. Micro-textures reveal that pyrite and pyrrhotite have a homogeneous distribution of trace elements at the individual grain scale, however, some micro-inclusions containing trace elements, including Co, Ni, Cu, Pb, Zn, Ag, Bi, and As, are identified. Pyrite and pyrrhotite are enriched in Co, Ni, Cu, Pb, Zn, Ag, Bi, As, Se, and Sb. However, PyII has higher Cu, Pb, Zn, Ag, and Bi, but lower Co, Ni, As, Sb, and Te concentrations than PyI. The variations of Co and Ni concentrations, as well as the Co/Ni ratios in pyrite and pyrrhotite demonstrate a link with the distance to ore-related granite. PyI has in-situ δ 34S values of –6.8 to –3.4 ‰ (average of –5.9 ‰), and PyII exhibits values ranging from –6.7 to –5.4 ‰ (average of –6.0 ‰). Pyrrhotite has δ 34S values ranging from –6.9 to –5.5 ‰. The in-situ sulfur isotopic compositions demonstrate a magmatic source for ore-forming materials, which were derived from the Early Cretaceous monzogranite. Trace elements and sulfur isotopic compositions of pyrite and pyrrhotite indicate that the formation of the Ag–Pb–Zn veins at Xiasai is due to a decrease of temperature, salinities, f S 2 and f O 2 of the hydrothermal fluids. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Nageng Ag mineralization age is limited to ca. 217–207 Ma. • Pyrite trace elements and δ 34S suggest a magmatic-hydrothermal origin. • Ag-Pb-Zn veins formed due to temperature, f S 2 , and f O 2 decrease. The Nagengkangqie'er (Nageng) silver deposit, situated in the Eastern Kunlun Orogenic Belt (EKOB), Northwestern China. It contains 5,070 tons of contained silver at a silver grade of 325 g/t. Nonetheless, the genesis of the Nageng silver deposit is still under debate, due to the absence of definitive constraints the mineralization age and the metal sources. The U-Pb data analysis of a post-ore calcite vein established the minimum age of the mineralization at 207 ± 3 Ma, whereas the maximum age of 217 ± 4 Ma was determined from zircon U-Pb data obtained from the altered and mineralized rhyolitic porphyry host-rock. These temporal limitations suggest that the mineralization formed at ca. 217–207 Ma, and it is associated with the post-collisional setting of the Paleo-Tethys evolution in the EKOB. The distinct textural patterns, as revealed by petrographic observations, suggest three types of pyrites: py1 is composed of euhedral pyrite in the early barren quartz vein at stage 1, py2 is represented by subhedral-anhedral grains in massive ore veins at stage 2, and py3 forms euhedral crystals of varying sizes, which are interspersed with early-formed marcasite in the quartz + calcite + silver-bearing sulfosalt-dominated veins at stage 3. In-situ δ 34S values of pyrites range between −2.33 ‰ and −0.37 ‰, indicating a dominantly magmatic origin. EPMA studies have revealed that silver in the Nageng deposit predominantly occurs as silver-bearing galena at stage 2, whereas silver is enriched in sulfosalts of stage 3. From py1 to py3, a decrease in the Co-content indicates a decrease in the ore-forming fluid temperatures. The presence of stage 3 sulfide, sliver-bearing sulfosalt, and calcite-quartz in a fracture-filled vein indicates low-pressure conditions during its formation, compared to stages 1 and 2. In summary, the Nageng deposit is a typical magmatic-hydrothermal vein-type Ag-Pb-Zn deposit. Fluid cooling and decrease in pressure, coupled with decreases in f O 2 and f S 2 , are the parameters inferred to have led to a decrease of silver solubility in the hydrothermal fluids and, successively, promoted extensive Ag deposition. [ABSTRACT FROM AUTHOR]

Sulfur isotope signatures of Au-bearing pyrite from Lannigou Au deposit, a typical Carlin-type Au deposit in SW China, provide valuable information about the origin of the ore-forming minerals. Analysis by NanoSIMS was used to determine S isotope compositions of Au-bearing pyrite and to map the grain-scale distributions of Au, Cu, As and S in pyrite from the deposit. Based on different textural pattern of pyrites revealed by back-scattered electron (BSE) images, they are divided into three types: Py-1 diagenetic pyrite without core-rim structure, Py-2 pyrite with an Au-free core and a rhythmically-zoned Au-bearing rim, Py-3 Au-bearing pyrite with rhythmic zoning across the entire grain. The element distributions and S isotope compositions of four paragenetic stages are recognized on the basis of textural observation. Py-1 grains and the Au-free homogeneous cores of zoned crystals were formed in Stage 1 while the Au-bearing rims of the zoned crystals with rhythmic zonation of As and Cu, and to a lesser degree Au, were formed in two superimposed stages: stage 2 formed the inner zone that is enriched in As alone; and stage 3 formed the outer zone that is enriched in both Au and As. Other sulfides such as realgar, cinnabar and stibnite are formed in the last stage. The relationship between Au and As distributions in pyrite rim is complicated, changing from coupled to decoupled at the nanoscale. Such complexity is interpreted to reflect fluctuation of fluid composition and temperature with time, which in turn affect the modes of occurrence of As and Au. It is inferred that As mainly occurs in the crystal lattice replacing S whereas Au is mainly present as nanoparticles that were trapped in pyrite during crystal growth. The Au-bearing rims of the zoned pyrite crystals are characterized by highly variable δ 34 S values from 1.1 to 18.1‰, which exceed the values of the Triassic calcareous host rocks (10–14‰). In contrast, the δ 34 S values of the Au-free cores of zoned pyrite crystals vary over a narrower interval and are mainly between 6 and 12‰, close to the values of pyrite crystals in the sedimentary country rocks. Our new analyses also reveals that the δ 34 S values of the Au-bearing fluids generally increase during the formation of the deposit. The observed S isotope variations are consistent with mixing between a magmatic-related fluid with mantle-like δ 34 S value (∼0‰) and a sedimentary or deep basin brine fluid with elevated δ 34 S value (>18‰), with an increasing contribution from the latter with time. The notably varied values of δ 34 S and the disseminations of Au and other trace elements such as As and Cu in pyrite crystals indicate that the process responsible for Au precipitation in this deposit occurred in an open hydrothermal system. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zircon U–Pb and sphalerite Rb–Sr dating yielded 136–135 Ma for monzogranite and Pb–Zn–Cu mineralization at Taolin. • A magmatic-hydrothermal origin was suggested for the Pb–Zn–Cu mineralization. • Ore-forming materials were derived from monzogranite with minor gypsum layers involved during the late stage. • The ore-related monzogranite was formed by crust- and mantle-derived magmas. The large Taolin Pb–Zn–Cu deposit contains 0.98 Mt Pb + Zn @ 2.35 % and 0.04 Mt Cu @ 0.1 %, and is associated with the Mufushan granitic complex in the central Jiangnan Orogen (JNO), South China. It consists of sulfides in hydrothermal veins, resulting from three successive mineralization stages (I–III). However, the geochronology of mineralization and ore-related granite, and sources of ore-forming fluids and materials are not well defined. Here we present zircon U–Pb dating for granite, Rb–Sr age of sphalerite, and H–O–S–Pb isotopes for ores that served to constrain the magmatism and mineralization at Taolin better. Zircon U–Pb laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) dating of the biotite monzogranite gave an age of 136 ± 0.8 Ma (MSWD = 1.8). Furthermore, an Rb–Sr isochron of sphalerite separates yielded an age of 135.4 ± 2.6 Ma (MSWD = 1.0). These results suggest that the intrusion of biotite monzogranite and Pb–Zn–Cu mineralization are contemporaneous with a close temporal relationship. δ D H2O values of quartz samples from stage II range from –67.4 % to –62.5 % and calculated δ 18O H2O values from –4.1 % to –1.8 ‰, indicating a mixing source of magmatic fluids and meteoric water for ore-forming fluids. S and Pb isotopic compositions of sphalerite and galena from stage II support the genetic relationship between the Pb–Zn–Cu mineralization and biotite monzogranite at Taolin and probably indicate a common source. However, previous high δ 34S values (12.6 ‰ to 17.7 ‰) for barite from stage III suggest the involvement of high sulfur isotopes, which could be derived from gypsum layers within the Early-Middle Triassic sedimentary strata. The ore-related biotite monzogranite, with ε Hf (t) values ranging from –6.8 to –3.0 and two-stage Hf model ages ranging from 1625 to 1383 Ma, was probably derived from Neoproterozoic lower crust with a minor injection of the asthenospheric mantle. Geochronological and isotopic data demonstrate a magmatic-hydrothermal origin for the Taolin Pb–Zn–Cu deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • LA–ICP–MS U–Pb dating of cassiterite yielded a Tera-Wasserburg U–Pb lower intercept age of 99.2 ± 0.8 Ma. • A magmatic-hydrothermal origin was suggested by trace elements in cassiterite. • Sn and Ag–Pb–Zn mineralization are associated with the same magmatic-hydrothermal system. • Spatial relationship can be used as a mineral exploration indicator. Tin and (Ag)–Pb–Zn mineralisation generally co-exist in SEDEX, porphyry, skarn, greisen, as well as magmatic-hydrothermal Sn and/or Pb–Zn polymetallic deposits. The genetic relationship between these two styles of mineralization, however, is not well defined. More than 20 skarn and hydrothermal-vein-type Ag–Pb–Zn–Sn deposits can be found in the central Yidun Terrane (YDT) of southwestern China. Amongst these is the large Xiasai deposit, which contains 1028 t Ag @ 337.8 g/t, 0.27 Mt Pb + Zn @ 8.33 %, and 20,000 t Sn @ 0.75 %. The deposit is zoned, comprising proximal cassiterite-quartz veins and distal Ag–Pb–Zn veins. We present micro-textural studies, LA–ICP–MS U–Pb dating results, as well as cassiterite major and trace element data that served to better constrain the link between the Sn and Ag–Pb–Zn mineralisation at Xiasai. Two types of cassiterite, i.e., Cst I and Cst II, can be distinguished using cathodoluminescence (CL) imagery. Cst I has a dull luminesce and oscillatory zonation, and it has been partially replaced by Cst II, which has a bright luminesce and a homogeneous texture. Whistle the SnO 2 and TiO 2 contents of Cst I and Cst II are similar, the latter has slightly higher FeO compositions (from bdl to 0.08 wt% and 0.01 to 0.11 wt%, respectively). LA–ICP–MS U–Pb dating of cassiterite yielded a Tera-Wasserburg U–Pb lower intercept age of 99.2 ± 0.8 Ma (n = 39, MSWD = 1.8), identical to the ages of granitic magmatism and Ag–Pb–Zn vein formations. LA–ICP–MS trace element analyses revealed that cassiterite is enriched in Ti and W, but depleted in Fe, Mn, Nb, and Ta. The Zr/Hf ratios of cassiterite range from 4.7 to 15.8 and Ti/Zr ratios range from 1.8 to 6.2. Overall, the measured Fe, W, Nb, and Ta concentrations, as well as the calculated Zr/Hf and Ti/Zr ratios, indicate that the cassiterite-quartz veins at Xiasai have a magmatic-hydrothermal origin. Our findings, when combined with previous micro-thermometrical fluid inclusion data (423–481 °C for Sn and 158–386 °C for Ag–Pb–Zn mineralisation), suggest that Sn and Ag–Pb–Zn mineralisation was cogenetic and linked to a common magmatic-hydrothermal system. The spatial relationship between Cretaceous A-type granitic magmatism and Ag–Pb–Zn–Sn mineralisation in the central YDT can be used as a guideline for mineral exploration of both skarn and hydrothermal veins. [ABSTRACT FROM AUTHOR]

The Yukeng–Banling deposit is a typical fault-controlled hydrothermal Cu–Au deposit in the Shanmen Volcanic Basin (SVB), SE China. Ore bodies commonly occur as lodes, lenses and disconnected pods dipping SW with vertical zonation of ore minerals. Ore-related hydrothermal alteration is well developed on both sides of the veins, dominated by silicification, sericitization, chloritization and argillation with a banded alteration zonation. The mineralization can be divided into three stages (stages I, II and III). Native gold is present as veinlets in fractures of fine-grained pyrite from stage II. Zircon U–Pb and Rb–Sr isochron ages indicate that the Cu–Au mineralization is coeval with the Caomen alkaline granite and Xiaokeng quartz-diorite, both emplaced at ca. 102 Ma. Microthermometric measurements of fluid inclusions in quartz and sphalerite from stage II veins indicate that the Yukeng–Banling deposit is an epithermal deposit. Six ore-related quartz grains have δ D H2O values of − 69 to − 43‰, and δ 18 O H2O values calculated using total homogenization temperatures that range from − 2.0 to 0.7‰. All samples plot in an area between the magmatic field and the meteoric line, suggesting that the ore-forming fluids are derived from a mixed source of magmatic and meteoric waters. δ 34 S values for eight pyrite separates range from − 2.1 to + 4.1‰ with an average of + 1.7‰, and δ 34 S values for galena and sphalerite are 2.3‰ and 2.2‰, similar to magmatic sulfur. Four alkaline granite samples have Pb isotopic ratios ( 206 Pb/ 204 Pb) t = 18.175–18.411, ( 207 Pb/ 204 Pb) t = 15.652–15.672 and ( 208 Pb/ 204 Pb) t = 38.343–38.800. Three quartz-diorite samples have ratios ( 206 Pb/ 204 Pb) t , ( 207 Pb/ 204 Pb) t and ( 208 Pb/ 204 Pb) t of 18.277–18.451, 15.654–15.693 and 38.673–38.846, respectively. These age-calculated lead isotopic data for alkaline granite are similar to those for the analyzed sulfides. Co/Ni ratios for stage II pyrites range from 1.42 to 5.10, indicating that the Yukeng–Banling deposit records the past involvement of magmatic hydrothermal fluids. The isotope data, together with geological, mineralogical and geochronological evidence, favor a primary magmatic source for sulfur and metals in the ore fluids. Mixing of the Cu- and Au-rich fluids with meteoric water led to precipitation of the Cu–Au veins along NW-trending faults. The Yukeng–Banling deposit, the contemporaneous Caomen alkaline granite and Xiaokeng quartz-diorite in the SVB formed under an extensional setting, due to high-angle subduction of the paleo-Pacific plate. The extensional setting facilitated the formation of Cu- and Au-rich magmas which was derived from enriched mantle and lower crust. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Giant Sb metallogenic belt in South China (GSMB) provides > 50% Sb production and reserves of the world. • Sb deposits in the GSMB are typically sedimentary-hosted and structurally controlled. • Sb deposits were mainly generated by low-temperature and low-salinity fluids. • Sb mineralization in the GSMB mainly occurred during 160–120 Ma. • Subduction of paleo-Pacific plate triggered Sb mineralization. The giant Sb metallogenic belt in South China (GSMB) has been proved to provide approximately half the world's reserves and Sb production. This metallogenic belt is tectonically located along the transition zone between the Yangtze and Cathaysia blocks, covering an area of ∼ 1900 km long and ∼ 200 km wide, with a set of large or giant Sb deposits such as the Xikuangshan, Banxi, Woxi, Qinglong, and Banpo-Banian. The Sb deposits have the following features in common: localisation in sedimentary rocks or counterpart metamorphic rocks as veins or strata, structural-tectonic control of mineralisation along the regional NE-trending faults, and the presence of intermediate-mafic dyke rocks in the belt whose relationship with Sb mineralisation is not obvious. Fluid inclusion data show that the Sb mineralisation in this belt generally occurred under low-temperature and low-salinity conditions (140–250 °C, 0.2%–10% NaCl equiv.). Abundant isotope data suggest that the Sb deposits in this belt were dominantly generated by crustal fluids from the Proterozoic basement sequences and fresh meteoric water or their mixture with various proportions, whereas the magmatic contribution to Sb mineralisation in this region is a preferential heat source rather than a material supplier (i.e., fluids and metals). The reported geochronological data of representative Sb deposits suggest an age distribution trend of Sb mineralisation, from 120 to 130 Ma in the Xikuangshan, Banxi, Woxi, Banpo and Banian Sb deposits in the northern and central parts of the GSMB, to 140–165 Ma in the Qinglong, Muli and Maxiong Sb deposits in the southern part of this belt. This age trend of the GSMB is largely comparable to that of Mesozoic igneous rocks in the Cathaysia Block, indicating both of them are the products of the west-northwestward flat-slab subduction and post-subduction of the paleo-Pacific Plate during the Late Mesozoic. In combination of the geological, geochemical, and reported geochronological data, we proposed that the Sb deposits in GSMB in South China probably have been mainly generated by low-temperature and low-salinity crustal fluids which leached Sb and S from basement sequences under an extensional setting during Late Mesozoic. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three stage Mesozoic magmatic activities in the DBO and the MLYRB almost in a similar duration. • Cu-Au mineralization is in the early stage for the MLYRB and Mo in the late stage for the DBO. • Three stage magmatic sources and their transformations are quite different for the two regions. • Broad continental arc and then back-arc for the MLYRB, and post-orogenic evolution for the DBO. • Magmatic source and physical–chemical condition, tectonic regime are key to mineralization. The Middle–Lower Yangtze River Belt (MLYRB) and the Dabie Orogen (DBO) are two contiguous tectonic units in which extensive late Mesozoic magmatism took place over similar time intervals. However, marked differences are observed in the geochemistry, lithology, and associated mineralization of the magmatic rocks of the two domains. Late Mesozoic magmatism in both regions can be divided into three stages (MLYRB: 148–133, 133–127, and 127–123 Ma; DBO: 143–130, 130–126, and 126–110 Ma). The MLYRB first-stage intrusions, which are closely genetically associated with Cu–Au polymetallic mineralization, are dominated by granodiorites characterized by higher Sr/Y ratios, arc-like trace-element distributions, moderately enriched Sr–Nd–Hf isotopic compositions, and higher radiogenic Pb isotopic values, indicating a mantle–crust mixed magma source. The mantle source was metasomatized by fluid and/or melt released from a subducted oceanic slab, and the crustal source was predominantly of Archean age, similar to late Archean to Paleoproterozoic basements in the MLYRB. However, the main metallogenic type in the DBO is Mo mineralization, whose ore-forming magmatic rocks are granites of the third stage of magmatism. The ore-barren magmatic rocks in the DBO are of the first and second stages of magmatism, with dominant rock types of adakitic granodiorite, andesite, and pyroxenitic or hornblenditic intrusions. In comparison, ore-forming rocks in the DBO show low Sr/Y ratios, less enriched Sr–Nd–Hf isotopic compositions, low radiogenic Pb isotopic values, and enriched light rare-earth element and large-ion lithophile element contents, which are geochemical signatures similar to those of the middle–upper crust represented by gneisses in the northern and central DBO. Separate tracing of the evolution of magmatic sources and deep processes of the two tectonic units during the three stages suggests that late Mesozoic magmatic activity in the MLYRB took place in a continental-arc geodynamic setting during the first stage, then transformed to a back-arc after the second stage. Northward flat subduction of the paleo-Pacific plate, followed by slab foundering and roll-back, provided not only the dynamic mechanism for the magmatism, but also a substantial material contribution. In contrast, late Mesozoic magmatic activity in the DBO, caused by an Indosinian continent–continent collisional orogen, occurred in a back-arc post-orogenic geodynamic setting, with orogenically thickened lithosphere preventing flat subduction. Subduction of the paleo-Pacific plate supplied the dynamic mechanism, but no material contribution to the magmatism of the DBO. A torn slab window formed along the present coordinates of the Yangtze River, corresponding to the Yangtze River fault, in the effect of sinistral shear of the Tan–Lu fault, a subordinate triggering dynamic setting for magmatism in the MLYRB. An integrated comparison of the two metallogenic belts suggests three key controls on metallogenic type: (1) Metal elemental abundance in the magma source was the first-order control on the minerogenetic series; (2) the physical–chemical conditions of the magma controlled the migration of metal elements from the source and incorporation into the metal-rich magma; and (3) the late Mesozoic tectonic regime exerted a broad influence on the generation of the different minerogenetic series. [ABSTRACT FROM AUTHOR]

[Display omitted] • The subducted South China Block metasomatized the subcontinental lithospheric mantle. • Subduction of the Paleo-Pacific Plate hydrated the subcontinental lithospheric mantle. • The gold-related lamprophyres had a high H 2 O and high fO 2 , which are felicitous for gold mineralization. Besides granite porphyries, many mafic dikes also have a close temporal and spatial relationship with orebodies in the BWGB. However, compared with the granite porphyries, no detailed attempt has been made to determine the petrogenesis of these mafic dikes or to elucidate their relationships with the gold mineralization. Here, we present comprehensive bulk-rock geochemical data; pyrite, apatite, and amphibole compositions; Sr-Nd-Pb isotopes, and U-Pb zircon data for the lamprophyres to provide constrains on their petrogenesis, magmatic properties, geodynamic setting, and metallogenic implications. We obtained zircon U-Pb ages, which reveal that the lamprophyres were emplaced ~ 130 Ma. The lamprophyres are characterized by pronounced light rare earth element (LREE) enrichment, heavy rare earth element (HREE) depletions ((La/Yb) N > 10). They also have low SiO 2 (<51 wt%) and high MgO (>4.1 wt%) contents; low Rb/Sr (0.01–0.04), Th/La (0.1–0.12), and Lu/Yb (0.13–0.16) ratios; high Ba/Rb ratios (>18), low Sr-Nd values (87Sr/86Sr(t) = 0.7060–0.7076; ε Nd (t) = –8.8 to –12.5); and a wide range of radiogenic Pb isotopic ratios (206Pb/204Pb(t) = 16.37–17.35), indicating an enriched mantle source metasomatized by the upper crust of the subducted South China Block (SCB). Their low apatite MnO contents and high apatite SO 3 contents, high apatite molar OH/F ratios, and high amphibole Mg* and VIAl* values suggest that the mafic magmas were more highly oxidized and hydrated. Taken together, the lithospheric mantle source was initially metasomatized by the SCB and was further hydrated by the subducted Paleo-Pacific Plate, resulting in a mafic melt with a high H 2 O content and oxygen fugacity value, which are favorable conditions for gold transportation. [ABSTRACT FROM AUTHOR]

• Cretaceous adakite-like and calc-alkaline granitoids occur in the Bengbu-Wuhe area. • Both types of granites are different in magmatic fO 2 , H 2 O-Cl contents, and sources. • The adakite-like rocks record conditions favorable for gold mineralization. Sinistral slip along the Tancheng–Lujiang Fault Zone (TLFZ) during the Mesozoic resulted in an offset of approximately 400 km between the Dabie and Sulu orogens. The Bengbu–Wuhe gold belt (BWGB) represents an extension of the Zhaoyuan–Yexian gold belt to the west of the TLFZ. Early Cretaceous intrusions are widely distributed throughout the BWGB. Gold deposits in the BWGB are commonly associated with intermediate acid dykes that are roughly contemporaneous with mineralization, and some orebodies are hosted in granitoids. This paper investigates granitoids within the BWGB to constrain their petrogenesis, tectonic setting, and metallogenic significance using systematic whole-rock elemental geochemistry, apatite geochemistry, zircon U–Pb dating, zircon Lu–Hf isotopes, and whole-rock Sr, Nd, and Pb isotopes. The timing of Au mineralization (134–113 Ma) in the area is consistent with the age of intrusive adakite-like rocks (130–115 Ma) and normal calc-alkaline granitoids (114–109 Ma). The adakite-like samples are characterized by pronounced enrichment in light rare earth elements (REE), depletion in heavy REE ((La/Yb) N = 30.5–66.2), an absence of Eu anomalies, high Sr contents and Sr/Y ratios, low Y and Yb contents, and fractionated REE patterns ((Dy/Yb) N = 1.22–1.69). They have relatively low Mg# values (38–42) and variable Sr–Nd–Pb–Hf isotopic compositions (87Sr/86Sr(t) = 0.7083–0.7111; ε Nd (t) = −22.2 to −14.9; 206Pb/204Pb(t) = 17.219–18.010; zircon ε Hf (t) = −21.0 to −12.3). These features indicate that the parental magmas of the adakites were derived from partial melting of thickened lower crust of the South China Plate and/or the North China Craton. The normal calc-alkaline granitoids have low Sr/Y (6.0–40.5), La/Yb N (6.8–24.7), and Dy/Yb N (0.90–1.28) ratios, exhibit negative Eu anomalies, and have variable Sr–Nd–Pb–Hf isotopic compositions (87Sr/86Sr(t) = 0.7082–0.7085; ε Nd (t) = −22.7 to −17.7; 206Pb/204Pb(t) = 16.686–16.713; zircon ε Hf (t) = −24.9 to −19.0), indicating they were derived from the middle to lower crust of the North China Craton. Compared with the normal calc-alkaline granitoids, the adakite-like rocks have higher zircon Ce4+/Ce3+, higher apatite SO 3 and lower apatite MnO contents, lower and more variable zircon crystallization temperatures, and higher apatite molar OH/F and Cl/F ratios, indicating that the adakitic magmas were more enriched in volatiles and more highly oxidized. Taken together, field observations and geochemical data suggest that the adakite-like rocks related to the subducted South China Block are the ore-causative rocks. [ABSTRACT FROM AUTHOR]

• Chemistry of magnetite is primarily reflective of evolution of ore-forming fluids. • High-V hydrothermal magnetite (V = ~10000 ppm) was discovered. • High-V magnetite formed in highly-reduced marine environments. The Dahongshan Fe-Cu ore deposit, hosted in the Paleoproterozoic meta-volcanic and meta-sedimentary sequences, is a giant deposit in the Fe-Cu metallogenic province of southwestern China. Two ore types have been identified: (1) massive and disseminated Fe ores hosted dominantly in meta-volcanic rocks and (2) disseminated and banded Fe-Cu ores in meta-sedimentary rocks. Magnetite presents in all orebodies, and is dominant in the Fe ores. Chemistry of magnetite suggest that the fluids for iron mineralization in the Fe and Fe-Cu orebodies are likely chemically similar and cogenetic. Minor sulfides (e.g., molybdenite) occur at the end of iron mineralization stage, indicating the gradually decrease in oxygen fugacity for the mineralizing fluids with magnetite precipitation. Along with evolution, mineralizing fluids generate magnetite with depletions in Cr, Ni, Ga and V, but enrichments in Mn, Sn and Co, which are primarily reflective of the temperature decrease of fluids. We have discovered some magnetite grains that are extremely rich in V (~10000 ppm), but low in Ti and Cr. Geochemical patterns suggest that they were formed by fluids similar to those of ordinary ores. Available knowledge about the unique high-V magnetite indicates highly-reduced marine environments for its generation. Ore bulk REE patterns showing remarkable positive Eu anomalies and absence of obvious Ce anomalies suggest a BIF-like marine environment, consistent with the morphology of both Fe and Fe-Cu orebodies. Our results provide independent evidence for submarine environment in the formation of the giant Precambrian stratiform Fe(-Cu) ore deposit. [ABSTRACT FROM AUTHOR]

• Breithauptite and ullmannite occur as inclusions in pyrrhotite. • Amounts of silver is incorporated in silver-minerals with a proportion of 88.7% for resource contribution. • Native bismuth occur as inclusions in galena with estimated Bi resource to large-sized. • Ore-forming materials derived from a monzogranite. • Ag–Pb–Zn mineralization was triggered by decreasing in T , f s 2 , and sulfidation. Sulfides and sulfosalts are major ore minerals for most of Ag–Pb–Zn deposits and can be used to study enrichment and distribution of ore-forming elements and formation conditions. The Xiasai Ag–Pb–Zn deposit (Zn 0.141 Mt @ 4.30%, Pb 0.132 Mt @ 4.03%, Ag 1028 t @ 337.8 g/t, Cu 10058 t @ 0.56%, and Sn 20000 t @ 0.75%) is a hydrothermal vein-type deposit in the central Yindun Terrane, SW China. It consists of proximal quartz-cassiterite veins and distal Ag–Pb–Zn sulfide veins to a Cretaceous monzogranite. Three successive mineralization sub-stages are recognized for Ag–Pb–Zn veins, i.e., arsenopyrite + coarse-grained pyrite (Py1) + pyrrhotite, sphalerite + chalcopyrite + fine-grained pyrite (Py2), and silver-minerals + native bismuth + galena. Nickel-minerals, such as breithauptite and ullmannite were identified as inclusions hosted within pyrrhotite using Energy Dispersive X-ray Spectroscopy (EDS) and Electron probe microscopy (EPM) analysis and mapping. Trace amounts of invisible silver have been detected in chalcopyrite and galena, whereas a significant amount of silver is incorporated in pyrargyrite, freibergite, miargyrite, and electrum as intimate intergrowths with galena or inclusions within galena. A high content of invisible bismuth is detected within galena (0.21–16.95 wt%), as well as numerous grains of native bismuth occur as inclusions in galena. Based on the Bi concentrations determined and the modal composition a large-sized bismuth deposit would be estimated with about 23,800 t of Bi resource. The presence of nickel-minerals and native bismuth, together with Zn/Cd ratios (58–151) of sphalerite, indicate that the ore-forming materials are derived from the Xiasai monzogranite. Based on mineral assemblages and chemical features for sulfides and sulfosalts, the formation of Ag–Pb–Zn ores was triggered by a decrease in temperature, f s 2 , f O 2 , and sulfidation. The early episode of arsenopyrite, Py1, pyrrhotite, and nickel-minerals formed at temperature of 320–470°C, lower f s 2 and decreasing sulfidation conditions from low alkaline fluids. In contrast, the late episode of silver-minerals, native bismuth, and galena deposited at 160–270 °C with a lower f s 2 state and neutral or acidic pH. However, a slight increase of f s 2 , f O 2 , and sulfidation (intermediate sulfidation) occurred during precipitation of Zn–Cu. [ABSTRACT FROM AUTHOR]

[Display omitted] • Banxi Sb deposit is characterized by Sb-only vein-type mineralization. • Ore-forming fluids at Banxi is dominated by basinal brines. • S in the fluids at Banxi was sourced from Proterozoic metamorphic rocks. • A new formation model is proposed for the Banxi Sb deposit. The Banxi Sb deposit (>100,000 t Sb metal with a grade of 0.02%–64.5% Sb (typically 15.3%–25.9% Sb) in the Eastern Yangtze Block is hosted in Neoproterozoic low-grade metamorphic clastic rocks of the Banxi Group. The deposit is characterized by vein-type Sb-only mineralization. Analyses of individual quartz-hosted fluid inclusions obtained by LA-ICP-MS identified Na as the most abundant cation (thousands to tens of thousands of ppm) in the ore-forming fluids of the Banxi Sb deposit, together with variable contents of K, Ca, Al, As, Fe and Sb (tens to thousands of ppm). Multiple chemical criteria, including high Na+/K+ (typically 3–15) and low Mn2+/Na+ (0.003–0.2) and Sr2+/Na+ (0.001–0.01) ratios of individual fluid inclusions, suggest that the fluids responsible for quartz and stibnite precipitation in the Banxi Sb deposit were likely dominated by basinal brines within low-grade metasedimentary rocks. Moreover, the extremely low 3He/4He ratios (0.001–0.048Ra) but relatively high 3He/36Ar (0.5 × 10−5–5.8 × 10−4) and 40Ar/36Ar ratios (323–1111 with an average of 737) of fluid inclusions trapped in ore-stage quartz further support a sedimentary origin of ore-forming fluids in this deposit. The positive and homogeneous sulfur isotopic values (δ34S = 8.0–9.5‰) of stibnite and arsenopyrite are comparable to those of sulfides in Proterozoic metasedimentary rocks (δ34S = 5.6–11.5‰), indicating these metasedimentary rocks may have served as the primary source of S for the Banxi Sb deposit. Combined with geological features and new trace element chemistry data for quartz and stibnite, we envisaged a new formation model for the Banxi Sb deposit that assumes that circulation of weakly alkaline basinal brines through faults under an extensional tectonic setting during the Early Cretaceous (∼130 Ma), mobilization of Sb and S from the underlying and host metasedimentary rocks and ascent of ore- forming fluids along faults, and ultimately precipitation of Sb minerals in or around fault/fracture zones as a result of the decreasing pH of the ore-forming fluids as well as sulfidation during fluid-rock reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • First- and second-order pulsed fluids of Mengya'a deposit are documented in garnet crystal. • The multiple fluid flow has more potential for large-size skarn metallogenesis. • The pulse frequency and pulse intensity of Sn in garnet are potential indicators of skarn Sn mineralization. Skarn deposits, which serve as a significant source of Pb, Zn, Fe, W, Cu, and Au, are typically formed through interactions between fluids and carbonate rocks. However, the discovery of skarn deposits faces obstacles due to a limited understanding of the factors influencing their size. Many studies increasingly assume that the presence of large skarn deposits may be closely associated with multi-stage fluid pulses. Nonetheless, this assumption has not undergone explicit testing. In this study, zoned garnet grains from the large Mengya'a Pb-Zn-polymetallic deposits were used to unravel the multi-stage fluid pulse and evolution within a magmatic-hydrothermal system. In-situ major and trace elemental analysis reveals that the garnets exhibit two distinct zones, namely Ti-Al-enriched (G1) and Ti-Al-poor (G2) zones. The G1 domains are characterized by high HFSEs, slight enrichment in heavy rare earth elements (HREE), and minor variable Eu anomalies, as well as a linear relationship between REE and Y concentrations. These observations suggest that their formation reflects the fluid flux in a nearly closed system. The G2 domains exhibit oscillatory zoning in Al, Fe, Sn, HFSE, and various other elements, reflecting the intermittent flow of fluids originating from a degassing magma reservoir. The Al-, Zn-, and HFSE-rich characteristics of G2, along with their low δEu anomalies in comparison to G1, are associated with fluids that have undergone multiple recharge events from a magma chamber containing a significant amount of meteoric water in an open system. The presence of Sn-rich and In-rich zones within G2, accompanied by high δEu anomalies, indicates a gradual cooling and evolution of the pulsed fluids, resulting in the enrichment of Sn and volatile elements in the remaining fluid. Consequently, it can be concluded that the contribution of multiple fluid flows from a recharged magma chamber, undergoing extended cooling and evolution, plays a pivotal role in the formation of large skarn deposits. An additional implication of this study is that the zoning of Sn in garnet serves as a crucial indicator of Sn mineralization within skarn deposits. [ABSTRACT FROM AUTHOR]

• We report trace element data of quartz at Xikuangshan and Woxi Sb deposits. • Major trace elements in quartz are controlled by (Al3+, Sb3+) + (Li+, Na+, K+) ↔ Si4+. • Two different precipitation mechanisms are responsible for two Sb deposits. • Giant Xikuangshan and Woxi Sb deposits were generated by different processes. Trace element concentration and distribution in hydrothermal quartz from the giant Xikuangshan and Woxi Sb deposits in southern China have been investigated in order to discuss the trace element differences between Sb deposits and shed new insights into their genetic processes. The LA-ICP-MS data reveal that Al, Sb, Li, Na, and K are the most important elements in quartz with concentrations of >10 ppm, which may primarily occur as solid solution within the crystal lattice in quartz, and are probably controlled by the coupled substitution of (Al3+, Sb3+) + (Li+, Na+, K+) ↔ Si4+. However, the significant differences in trace element composition are suggestive of different precipitation mechanism of hydrothermal quartz at two giant Sb deposit. The higher and relatively homogenous Al concentrations suggest that quartz from the Xikuangshan deposit may have precipitated from more acidic fluids at presumably relative stable pH compared to the Woxi deposit. In contrast, the lower but variable Al concentration in quartz at Woxi is suggestive of a less acidic fluid with significant fluid pH fluctuations that may have driven metal-sulfide precipitation from ore fluids. Moreover, the higher and relatively variable Ti and Ge concentrations in quartz at Woxi are indicative of a higher and dramatic change of fluid temperature during precipitation processes; whereas quartz at Xikuangshan has lower and homogeneous Ti and Ge concentrations, reflecting smaller temperature fluctuations during quartz formation. Additionally, the quartz from the Xikuangshan deposit contains higher Li, Na, K, and Ca concentrations compared to that of the Woxi deposit, suggesting that the quartz-precipitating fluids at Xikuangshan are more enriched in alkali metals. The significant difference in trace element composition of hydrothermal quartz is good evidence for different precipitation mechanisms for two giant Sb deposits: quartz precipitation at Woxi deposit may have resulted from fluid mixing that would lead to dramatic changes of the fluid pH and temperature; whereas fluid boiling is likely the primary mechanism of quartz and sulfide-metal precipitation at Xikuangshan, which caused a smaller fluctuation of fluid temperature during quartz precipitation, and the stable fluid pH was buffered by interaction of boiling ore fluids with wall-rock carbonates. [ABSTRACT FROM AUTHOR]

• Low sulfidation epithermal gold deposit is genetically related to volcanic rocks. • Ore deposition is triggered by the mixing of magmatic fluid and meteoric water. • Low and intermediate sulfidation epithermal gold deposits co-exist at Dongkeng District. Low sulfidation (LS) epithermal gold deposits within the Southeastern China Fold Belt (SCFB) are generally associated with Early Cretaceous volcanism (91–110 Ma). The Shangshangang (SSG) gold deposit (3 t Au @ 2.7 g/t) is proposed to be a LS ore system hosted by Early Cretaceous volcanic-subvolcanic rocks in the Dongkeng Basin (DVB), northern SCFB. Early Cretaceous felsic volcanic-subvolcanic rocks within the DVB possess high-K calc-alkaline and metaluminous to weakly peraluminous signatures. They show rare trace element (REE) and trace element patterns resembling those of Early Cretaceous A-type granites and rhyolites in the SCFB with significantly Eu negative anomalies (Eu/Eu* = 0.1–0.3). These volcanic-subvolcanic rocks are potentially formed by mixing of melts from crust and Early Cretaceous enriched mantle under an extensional tectonic setting. This is indicated by their negative ε Hf (t) values (−8.8 to −5.2), young two-stage Hf model ages (T DM2 = 1.32–1.48 Ga), and variable Sr-Nd isotopic compositions. The epithermal event at SSG is represented by three mineralization stages characterized by four distinct quartz vein types. These are: (1) greyish green crustiform comb quartz veins (type A) and smoky grey fine-grained (<0.5 mm) quartz veins (type B) in the early stage, (2) ivory medium- to coarse-grained (>1 mm) quartz veins (type C) in the middle stage, and (3) late white calcite-rich quartz veins (type D). Quartz veins are typically accompanied by hydrothermal alteration with zoning (kaolinite-illite-chlorite zone, adularia-chlorite-quartz zone, and adularia-sericite-quartz zone). Gold mineralization is identified in the early stage and free gold exists as micrometer-sized inclusions of native gold within pyrite. Pb–Zn mineralization dominates the middle stage. Hydrothermal fluids within the ore system are of low salinity (<7 wt% NaCl) and gas-poor. The fluid temperatures decreases from 224 − 316 °C for Au mineralization to 190–261 °C for Pb-Zn mineralization. No indication for fluid boiling is found. The H–O isotopes indicate mixing of magmatic and meteoric fluids and a larger portion of meteoric water at a later stage. The δ 34S values of pyrite related to Au mineralization are 1.1–2.0‰ and of sphalerite and galena related to Pb-Zn mineralization range from −1.8 to 2.5‰. The Pb isotopic compositions of sulfides from the early and middle stages are relatively homogeneous and similar with those of subvolcanic rocks within the DVB. Deposit geology, microthermometric result, and isotopic data support a LS epithermal origin for the SSG gold deposit, and therefore suggest a co-existing relationship between low and intermediate sulfidation epithermal gold mineralization within the DVB. [ABSTRACT FROM AUTHOR]

• The Sb mineralization in the Banxi deposit primarily occurred during 130–120 Ma. • Zircon (U-Th)/He system in altered host rocks can be completely reset by hydrothermal Sb mineralization and record its age. • This study proves zircon (U-Th)/He dating can be viable for constraining the timing of low-temperature hydrothermal mineralization. The Banxi Sb deposit is one of world-class Sb deposits located in the Xiangzhong Sb-Au metallogenic province in southern China. However, the mineralization age of this deposit is still not well constrained due to a lack of suitable minerals for reliable radiometric dating. Since the fluid-inclusion data suggest that the temperature of ore-forming fluids in the Banxi deposit is up to 330 °C, zircon (U-Th)/He thermochronometry with the closure temperature of 160–200 °C was chosen here to elucidate the timing of Sb mineralization of this deposit. Detrital zircons within three samples of altered host rocks in the Banxi deposit yielded (U-Th)/He dates of 132–113 Ma (weighted mean = 121 ± 12 Ma), 132–124 Ma (weighted mean = 129 ± 3 Ma) and 142–113 Ma (weighted mean = 125 ± 10 Ma), respectively, which are broadly consistent with the Rb-Sr and Sm-Nd isochron ages of hydrothermal sulfide minerals (~130 Ma). Combining with the reported ages of adjacent Sb deposits, we propose that Sb mineralization in the Banxi deposit may have primarily taken place during 130–120 Ma. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyrite of Carlin-type Au deposits in the Youjiang Basin were analyzed by Nano-SIMS. • The δ34S values Au-bearing pyrite of Linwang vary inversely with Au concentrations. • Initial auriferous fluids of Linwang were sourced from magmatic-hydrothermal systems. • Reduced sulfur in ore-forming fluids of Badu was dominated by sedimentary sulfur. • Sedimentary sulfur contamination result in variable δ34S values of Au-bearing pyrite. The Youjiang Basin in Southwest China is the world's second largest Carlin-type gold (Au)-producing region. However, the source of reduced sulfur that accounts for Au transport in ore-forming fluids remains controversial. Finely characterizing the sulfur isotopic compositions (δ34S values) in micron-scale zonation of Au-bearing pyrite is the key to clearly identify sulfur source. Here, we used high-resolution nanoscale secondary ion mass spectrometry (Nano-SIMS) to characterize the temporal variation in δ34S values and its relationship with metal contents across Au-bearing pyrite from the Linwang and Badu deposits in the Youjiang Basin, with the aim of monitoring the source and evolution of reduced sulfur in auriferous fluids. The Au-bearing pyrite rims in the Linwang deposit contain three growth stages that record episodic injections of Au- and As-rich fluids. Within these rims, the δ34S values vary inversely with Au concentrations. The inner rims with the high Au contents have δ34S values of −1.7‰ to +3.3‰ that are comparable to those of magmatic sulfur. The outer rims with decreasing Au contents have δ34S values of +1.3‰ to +15.7‰ that gradually approach those of pre-ore pyrite in the host rock. Such a variation indicates that the reduced sulfur in the initial Au-bearing ore-forming fluids was primarily originated from deep magmatic-hydrothermal systems while the host rock-derived 34S-enriched sulfur increasingly dominated through fluid-rock interactions during mineralization. In contrast, Au-bearing pyrite from the Badu deposit has positive δ34S values ranging from +9.0‰ to +25.8‰, which overlap those of diagenetic pyrite in the Devonian sedimentary rocks. Combining the intimate spatial association between Au mineralization and the Devonian strata, we propose that the initial ore-forming fluids have leached substantial sulfur from the Devonian strata. Significant contaminations of sedimentary sulfur erased the primary sulfur isotopic signals of the initial auriferous fluids. Our interpretations of these two deposits may also apply to other Carlin-type Au deposits in the Youjiang Basin, where δ34S values of Au-bearing pyrite show host rock-dependent variations. This study demonstrates that high-resolution Nano-SIMS sulfur isotope and elemental analysis of Au-bearing pyrite is a potent tool for tracing the source and evolution of reduced sulfur in ore-forming fluids for sedimentary-host Au deposits worldwide. [ABSTRACT FROM AUTHOR]

Shuiyindong is one of the largest and highest grade stratabound Carlin-type gold deposits in China. This paper reports on the results of petrographic studies, electron microprobe analyses (EMPA) of arsenian pyrite, and the mass transfer during mineralization and alteration, and it presents the deposit-scale distributions of Au, As, Sb, Hg, Tl, and trace elements in a representative cross section across the Shuiyindong Carlin-type gold deposit, Guizhou Province. The main objectives were to identify the precipitation mechanisms of minerals, or elements from fluids, and the migration paths of ore-forming fluids. Petrographic and EMPA studies indicate that gold in the primary ores is mainly hosted by arsenian pyrite. Mass transfer associated with alteration and mineralization shows that Au, As, Sb, Hg, Tl, and S were significantly added to all mineralized rocks, Fe 2 O 3 and SiO 2 were immobile in the main orebodies that are hosted in bioclastic limestone, and CaO, Na 2 O, Sr, and Li were removed from country rocks. The relations between Fe and S indicate that the sedimentary rocks at the Shuiyindong deposit contain more iron than is needed to combine with all of their contained sulfur to form pyrite. This suggests that sulfidation and decarbonation were the principal mechanism of gold precipitation at the Shuiyindong deposit. Hg, Sb, and As commonly formed sulfide minerals, such as stibnite, realgar, and orpiment, in late-stage quartz–calcite veins, or absorbed by organic matter in argillite. Fluid cooling presumably led to depositions of stibnite, realgar, and orpiment in late-stage quartz–calcite veins. Organic matter likely served as a reductant in argillite for the ore fluids, causing the precipitation of As, Sb, Hg, and S, as well as Au. Deposit-scale distributions of gold and other relevant elements reflect the passage of fluids through the rocks. Rock strata and structures allowed the ore-forming fluids to migrate horizontally along the unconformity surface of the Middle–Upper Permian, converge on the high position of an anticline, and then ascend into the overlying strata along the anticlinal axis. The distributions of the major and trace elements show that elements that accompanied the ore-forming fluids include Au, As, Sb, Hg, Tl, and S, and that Na 2 O and Li were exhausted in the Longtan Formation at the anticlinal core during gold mineralization. The enrichment of Co, Cr, and Ni in the Longtan Formation at the anticlinal core might be associated with deformation that formed the anticline, or with gold mineralization. Different host rocks were preferentially mineralized by different elements. The bioclastic limestone is commonly enriched in Au, whereas the argillite is preferentially enriched in As, Hg, Sb, and Tl. The zonation of ore-forming elements in the deposit appears to be Sb–Tl–As–Hg–Au–Hg–As (from bottom to top). Enrichment of Au, As, Sb, Hg, and Tl provides useful guidance for the exploration for Carlin-type gold deposits in Guizhou. Anomalies of As and Hg in soil or stream sediment might be an important clue and these elements can be used as indicator elements. Ore-forming fluids migrated along the unconformity surface of the Middle–Upper Permian and the anticlinal axis, so these are favorable sites for exploration for Carlin-type gold deposits in Guizhou. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Beimulang is a newly discovered porphyry Cu deposit in the Gangdese belt. • There are at least two episodes of fluid exsolution events of granites at Beimulang. • The highly oxidized and hydrous magmas are crucial to form porphyry Cu deposits. The porphyry Cu deposits in the Gangdese metallogenic belt were mainly formed in the eastern portion. The Beimulang is a newly discovered deposit formed in post-collisional setting in the western part of the belt and adjacent to the super-large Zhunuo porphyry Cu deposit. There are three epochs of magmatism at Beimulang, including pre-mineralization quartz porphyry (PQP; 49.7 ± 0.4 Ma), inter-mineralization monzogranite porphyry (IMGP; 14.8 ± 0.2 Ma), monzogranite (IMG; 14.1 ± 0.2 Ma), and late-mineralization granite porphyry (LGP; 11.7 ± 0.1 Ma). The various degrees of alteration and sulfide occurred at the IMG(P) and LGP indicate that there are at least two episodes of fluid exsolution events associated with different intrusions spanning ∼ 3 m.y. at Beimulang, which are unlike other Gangdese porphyry Cu deposits showing single fluid exsolution around only one porphyry at Miocene (e.g., Qulong, Zhunuo, Dabu). The PQP is characterized by high SiO 2 (75.6–81.4 wt%) and K 2 O (2.1–4.3 wt%) concentrations, high Nb/Ta (8.4–11.3) ratios, and low Mg# (22–43), Ni (1.5–2.7 ppm) contents. They have high (87Sr/86Sr) i (0.705098–0.707767) ratios and low ε Nd (t) (-4.9 to −1.9) values. These geochemical characteristics indicate that they were probably derived from a juvenile basaltic lower crust during the ongoing Indian-Asian collision. The IMGP and IMG show similar petrography and geochemical characteristics, such as high SiO 2 (65.0–69.8 wt%), K 2 O (3.6–4.3 wt%), Sr (550–809 ppm) contents, high Sr/Y (79–89) ratios, and low Mg# (43–48), Th/Yb, and Nb/Yb values, combined with high (87Sr/86Sr) i (0.707254–0.708017) and low ε Nd (t) (-7.9 to −6.0), implying a similar source probably originated in the subduction-modified lower crust metasomatized by Neo-Tethyan oceanic slab-derived fluids. The LGP displays trends produced by fractionation of magma with a composition similar to the IMG(P), but wall rock assimilation plays a significant role during magmatic evolution. Zircons from the IMG(P) show higher Eu/Eu* (>0.3), 10000*(Eu/Eu*)/Y (>4), and (Ce/Nd)/Y (>0.04) ratios than those of the PQP, indicating the fertile magmas were more oxidized and hydrous. The high magmatic oxidation state for the IMG(P) is also supported by using the zircon (ΔFMQ = +4.1 to + 6.1), and amphibole (ΔFMQ =+2.6 to + 3.4) oxybarometers. Their high magmatic water contents are supported by evaluations using amphibole (∼3.5 wt%) and plagioclase (∼6.7 wt%) compositions, respectively. However, the LGP has higher magmatic oxygen fugacity (Eu/Eu* >0.3, ΔFMQ = +4.2 to + 7.3) caused probably by auto-oxidation of the magmas, but lower magmatic water contents (Sr/Y = 31 ± 15; V/Sc = 6 ± 4) caused presumably by previous fluid exsolution and/or fractionation of hydrous silicate minerals during magma ascent than those of the IMG(P). Therefore, the highly hydrous and oxidized magmas with juvenile material are favorable to form porphyry Cu deposits in Tibetan orogen. On the contrary, magmatic evolution can probably reduce the water content of magma chamber, which is not beneficial to porphyry Cu mineralization. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study first highlights the importance of melanite in-situ U-Pb geochronology. • Mineralization at the Mengya'a deposit is precisely identified at 55–52 Ma. • Ti-bearing andradites will potentially become an invaluable geochronological tool for skarn Pb-Zn deposits. Ti-bearing andradite (Ti-Grt) occurs in a variety of geological environments, such as Si-unsaturated igneous rocks, high-temperature metamorphic rocks, and contact-metasomatized skarns. This type of garnet remains stable throughout a wide range of pressure-temperature conditions. Abundant skarn Pb–Zn deposits, where the ore-related pluton is not exposed, have been discovered along the eastern Nyainqentanglha metallogenic belt, western China. However, the mineralization age of these skarn Pb–Zn deposits remains controversial. Therefore, in this study, petrography, geochemistry, and in-situ U–Pb geochronology of the Ti-Grt are investigated together with the Re–Os geochronology of the molybdenite in the large Mengya'a Pb–Zn deposit. The potential of Ti-Grt dating is explored and the age relationships between the skarn alteration and the Pb–Zn mineralization are constrained. The results show Ti-Grt samples from the Mengya'a deposit are brown-black in color with TiO 2 -rich (mean of 3.47 wt%) features. Laser ablation inductively coupled plasma mass spectrometry dating showed that these Ti-Grts have a U–Pb age range of 54.9–53.8 Ma, which is consistent with the ages of two adjacent molybdenite Re–Os models (53.36–52.86 Ma). This indicates that the skarn alteration is temporally associated with a Pb–Zn mineralization event during the Indian-Asian main-collisional orogeny. The positive linear Ti vs. U correlation of the Ti-Grts and other compiled data indicate that Ti-bearing garnets may have high contents of U. The incorporation of U and Ti in garnet is largely controlled by the crystal chemistry of garnet and the components of hydrothermal fluids in a nearly closed system. Thus, this study confirms the reliability and accuracy of in-situ U–Pb dating of Ti-Grt and emphasizes that Ti-bearing garnets can become an invaluable geochronological tool for magmatic, metamorphic, and hydrothermal mineral assemblages. [ABSTRACT FROM AUTHOR]

[Display omitted] • The special effects of vapor-phase fluids on hydrothermal sulfides are firstly reported. • Raman spectroscopy revealed sulfides composition changed and low degree of crystallinity. • Isotopic combined element analyses confirmed vapor-phases fluids affect sulfide compositions. Inverted lakes filled with shimmering water are unique environments within hydrothermal systems. Recently, vapor-phase fluids have been detected on the top of an inverted lake in a mushroom cap-shaped (MC) sulfide structure based on in situ Raman spectra at the Yokosuka Site in the Okinawa Trough (OT). However, the effects of vapor-phase fluids on the migration and metallogenic characteristics of elements remain unclear. To characterize the influence of such fluids, a comparative study of the micro-Raman spectroscopy, electron microprobe analyses (EMPA), polarizing microscopic, element distribution, and S-Pb isotopic composition among the hydrothermal sulfides collected from MC area, the middle Okinawa Trough (MOT) and southern Okinawa Trough (SOT), was conducted. Raman spectra show that the dominant band of chalcopyrite in MC sulfide generated a blue shift, while sphalerite generated a red shift, indicating that compositional differences exist in MC sulfide samples compared to the other two areas. This was also confirmed by EMPA data for these two minerals. Moreover, the full width(s) at half maximum (FWHM) of the Raman spectra of minerals in the MC sulfide samples showed a lower degree of crystallinity influence by the vapor-phase fluids. Elemental analyses further demonstrated that the MC samples share a particular elemental composition. That is, MC sulfides featured high Mn, Ba, and Sr and low Fe, Cu, Zn, Pb, Bi, Mo, Cd, and Ga. The same enrichment trends were observed among Ba–Sr, Cu–Mo, Cu–Bi, Zn–Pb, Zn–Cd, and Zn–Ga. Moreover, the δ34S of 5.44–5.85‰ in these deposits suggest that S was contributed by the underlying basalt, sediments, and seawater. The Pb isotopic composition of MC sulfides exhibited the same compositional patterns as the other sulfides and the underlying sediments at the SOT site, indicating that the sedimentary contribution of Pb has increased. The S–Pb isotopic composition suggests that a hydrothermal source may not serve as the primary cause of differences in the MC deposits. Instead, the unique vapor-phase fluids and other gaseous components may have predominantly affected the precipitation and migration of elements at this site. Although the shimmering water regions of inverted lakes accompanied by vapor-phase fluids are difficult to observe in deep-sea hydrothermal systems, here, we describe the geochemical characteristics of sulfides affected by this particular vapor-phase fluid, providing a unique perspective on the migration and precipitation occurring during sulfide deposit formation. [ABSTRACT FROM AUTHOR]

The parental magmas of the Cilincuo, Rongyicuo and Hagela plutons are less oxidized (a) and contain less H 2 O and Cl (b) than those associated with typical porphyry Cu-Mo mineralization. [Display omitted] • Zircon U–Pb ages of the three Cu–Mo barren plutons range from 98 to 86.1 Ma. • There are different magma oxidation states and H 2 O–Cl contents between the three Cu-Mo infertile plutons. • The Cu–Mo infertility of the three plutons is related to the low H 2 O–Cl content and oxygen fugacity in the causative magmas. The Yidun Cu-Mo polymetallic metallogenic belt, located in the eastern Tibetan Plateau, is well known for numerous Mesozoic porphyry Cu–Mo deposits. The Cu-Mo deposits are only concentrated in the southern part of the belt while the granites situated in the north are generally barren in Cu-Mo mineralization. To understand the cause of Cu and Mo infertility, geochronology and petro-mineral geochemistry of three Cu- and Mo-barren granite plutons (Cilincuo, Rongyicuo, and Hagela) in the Northern Yidun Terrane were investigated. Petrogeochemical characteristics and zircon U-Pb dating (95–85 Ma) along with the tectonic evolution history confirmed that the three plutons formed in a Late Cretaceous intracontinental setting. The whole-rock geochemical compositions showed that these plutons can be classified as A-type granites and have undergone extensive magmatic differentiation. Based on the calculated magmatic oxygen fugacity using zircon composition and a set of geochemical criteria including whole-rock Sr/Y ratios, Eu/Eu* and Fe3+/Fe2+ values as well as apatite Cl-H 2 O contents, the parental magma of the Cilincuo pluton was identified as more oxidized and H 2 O-Cl-rich than those of the Rongyicuo and Hagela plutons. These features enable the Cilincuo pluton to have an elevated capacity of Cu mineralization compared to the other two plutons. However, the causative magmas of the three plutons are still not enough hydrous and oxidized for typical porphyry Cu ± Mo mineralization. The whole-rock Sr-Nd isotope values of these three plutons are consistent with Late Triassic Cu and Mo barren granites in the same region such as Dongcuo, Cuojiaoma and Sucuoma, suggesting that they were derived from a similar magma source which might lack the oxidized and hydrous Neoproterozoic arc root remnant. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using pyrite Re–Os dating to confirm the timing of gold mineralization. • Investigating the occurrence and deposition mechanism of visible and invisible gold related to pyrite. • Gold deposits within the Dongkeng volcanic basin have an intermediate-sulfidation epithermal origin. The Dongji (>12.5 t Au @ 4.27 g/t) and Maluntou (>5.0 t Au @ 3.70 g/t) gold deposits are the two largest ones in the Dongkeng Volcanic Basin (DVB), SE China, that are hosted by volcanic rocks. Mineralization is represented by three stages (i.e., stage 1, 2, and 3) that are characterized by four types of unzoned hydrothermal pyrite (i.e., pyrite1, 2a, 2b, and 3). Hydrothermal fluids responsible for pyrite1 deposition are moderate temperatures (308–377 °C) and low salinity (4.6–9.1 wt% NaCl equiv.). The deposition of pyrite2a and 2b is related to the stage 2 fluids featured by moderate-low temperatures (253–341 °C) and low salinity (3.2–9.1 wt% NaCl equiv.). Pyire3 is deposited from the stage 3 fluids with low temperatures (220–250 °C) and salinities (1.0–6.5 wt% NaCl equiv.). Hydrothermal fluids potentially have a magmatic origin and experience fluid boiling and mixing of meteoric water. Scanning electron microscopy and laser ablation inductively coupled plasma-mass spectrometry were used to investigate the occurrence of visible gold and the distribution of invisible gold in pyrite from different generations. Visible gold mainly exists as native gold and electrum within crystal interstices, fractures, and hollows of pyrite2b, and precipitates directly from the fluids during fluid boiling at ca. 329 °C with pressure of ca.120 bar. Invisible gold mainly presents in the form of solid solution in all pyrite types. Solid solution gold is also closely related to pyrite2b as the measured Au concentrations in pyrite2b (up to 27 ppm) exceed those in other pyrite types (<0.6 ppm) by one or two orders of magnitude. The elevated content of invisible Au (together with As, Ag, Zn, and Sb) in pyrite2b is potentially associated with lattice dislocations caused by rapid precipitation of Py2b during boiling process. The Re–Os isochron age of pyrite2b (99 ± 10 Ma) and the zircon U–Pb dating of the volcanic and subvolcanic rocks (95.1–104 Ma) indicate that the formation of gold mineralization and the igneous activity in the DVB were coeval during the Turonia–Albian. Geochronology, fluid characteristics, together with low Ni concentrations (<98 ppm) and high mean Co/Ni ratios (≥2.0) of pyrite from different generations, support that the Dongji and Maluntou gold deposits formed in a magmatic-hydrothermal ore system and have an intermediate-sulfidation epithermal origin. [ABSTRACT FROM AUTHOR]

The apatite chemical compositions show that the parental magma of the Pulang pluton is more fertile for Cu mineralization than those of the Cuojiaoma, Dongcuo, and Daocheng plutons, because it is more oxidized and richer in Cu, Cl, and S. • Apatite is an efficient probe for magmatic fertility. • The parental magma of the Cu-mineralized Pulang pluton is more fertile than that of the non-mineralized plutons. • The difference in magmatic fertility results from magma sources. The Paleo-Tethyan granitoids in eastern Tibet are generally Cu-barren, and only a few can generate porphyry Cu deposits. It is still unclear what magmatic differences cause these coeval granitoids to have different mineralization potentials. In this study, the major, minor, and trace element abundances and Nd isotope in the apatites from four Triassic granitoids from eastern Tibet have been determined using EPMA, LA-ICP-MS, and LA-MC-ICP-MS. The following are the selected plutons: the Pulang pluton, which is associated with the porphyry-type Cu deposit, and the coeval Cuojiaoma, Dongcuo, and Daocheng plutons, three of which do not generate any Cu mineralization. Our study reveals that Ga, Ce, S, Cl, and Cu in apatite are effective indicators for both magmatic oxidation states and the abundances of volatiles and ore-forming metals. The Nd isotope of apatite can be used to trace the magma source. According to the above chemical compositions of apatite and Ce4+/Ce3+ ratio of zircon, the parental magma of the Pulang pluton is identified to be more fertile for Cu mineralization than those of the other three plutons, i.e., Cuojiaoma, Dongcuo, and Daocheng, because it is more oxidized and richer in Cu, Cl, and S. The aforementioned differences in magmatic physical and chemical conditions among the plutons investigated are ascribed to the different sources and natures of magmas, as revealed by both the Nd isotope and δEu, Sr/Y, and La/Yb values of apatite. Generally, the results indicate that magmatic fertility mainly governs the Cu-mineralization potential of Paleo-Tethyan granitoids in eastern Tibet, and that apatite is a robust probe for magmatic fertility. [ABSTRACT FROM AUTHOR]

• Xinqiao and Taoyuan deposits are typical stratabound massive sulfide deposits. • Colloform (Py1), fine-grained (Py2) and medium- to coarse-grained (Py3) are identified. • Pyrites are magmatic-hydrothermal origin. • Stratabound ore precipitated from the magmatic-hydrothermal fluid. • A sedimentary component was involved in the stratabound mineralization. Stratabound massive sulfide deposits are widely distributed along Middle-Lower Yangtze River metallogenic belt, in eastern China. There has much debate as to whether these deposits were associated with Late Mesozoic igneous or Carboniferous sedimentary exhalative (SEDEX). Three-type pyrites, i.e., colloform (Py1), fine-grained (Py2) and medium- to coarse-grained (Py3), from Xinqiao and Taoyuan stratabound massive sulfide deposits in Tongling region were investigated using electron probe microanalysis (EPMA), in-situ laser-ablation inductively-coupled plasma-mass spectrometry (LA-ICP-MS) and sulfur isotopic analysis. The analytic data indicate that the three-type pyrites have high S and As, and relatively consistent Au contents. The Au, Ag, Bi, Sb and Pb elements are mainly of lattice bound appearance in the Xinqiao and Taoyuan pyrites. Low Au (mainly < 5 ppm) and Ni (commonly < 10 ppm) contents, high Co/Ni (mainly > 1), Se/Tl (mainly > 1) and δ34S CDT (4.0‰ to 5.9‰) values of the studied Xinqiao and Taoyuan pyrites imply a magmatic-hydrothermal origin. High Bi (>1 ppm) and Mo contents, and low Co/Ni ratios (<0.1) of the studied Xinqiao and Taoyuan pyrites reflect a sedimentary contribution to the magmatic-hydrothermal system. Combined with previous results, the Xinqiao stratabound mineralization is most likely to be genetically with the magmatic-hydrothermal fluids by the addition of a sedimentary component. [ABSTRACT FROM AUTHOR]

The summary plot of logarithmic Al concentrations versus δ18O fluid of Yata and Qinglong deposits shows three categories represented as initial fluid, Au metallogenic fluid, and Sb metallogenic fluid. The Carlin-type Au deposit and vein-type Sb deposit in the YMP were similar in origin of ore fluids. Different lithologies of wall rocks and the dilution of meteoric water controlled the compositional evolution of fluids. • The initial fluids of the Yata and Qinglong deposits are comparable. • Interaction between fluids and wall rocks determines variations of fluids in Au mineralization. • Meteoric water is a considerable influence in Sb mineralization. Abundant Carlin-type gold deposits and vein-type antimony deposits were discovered in the Youjiang basin of SW China, constituting the Youjiang Metallogenic Province (YMP). Although they had been widely studied by geologists, the genesis of these deposits remains debatable, while both intrusion-linked and non-intrusion linked models have been proposed. In this paper, new data of in situ trace elements (LA-ICP MS) and oxygen isotope (SIMS) analysis of hydrothermal quartz from the Yata Carlin-type gold deposit and the Qinglong vein-type antimony deposit in the province were provided to better understand the origin of ore-forming fluids as well as the genetic mechanism of Au and Sb mineralization. Four quartz generations were identified from the Yata (YTi to YTiv) and the Qinglong (QLi to QLiv) deposits. In the Yata deposit, the fluid inclusions in quartz have varied homogenization temperatures from 140–260 ℃ and salinities of 2.4–7.4 wt％ NaCl eq , while in the Qinglong deposit, the temperatures and salinities ranged from 140–200 ℃ and 0.2–7.2 wt％ NaCl eq., respectively. Both of the temperatures and salinities tend to decrease from early to late generations in the two deposits. δ18O values of initial fluids in the Yata (YTi: 7.70–10.56‰) and the Qinglong (QLi: 4.66–8.75‰) deposits are similar and suggest that they were mainly from magmatic or metamorphic fluids. The covariability of oxygen isotope and Al concentrations indicate that interaction between fluids and wall rocks is a significant factor in determining the compositions of fluids in Au mineralization, and the meteoric water is a key proxy in Sb mineralization, respectively. From these observations, we proposed that the Carlin-type Au deposit and vein-type Sb deposit in YMP were sourced from an analogous ore fluid. Different lithologies of wall rocks and the dilution of meteoric water controlled the compositional evolution of fluids, which might be the main reason for the diversity of Au and Sb mineralization. [ABSTRACT FROM AUTHOR]

• Use LA-ICP-MS and SIMS technique analyzed trace elements and carbon, oxygen isotopes of calcite in Youjiang basin Carlin-type gold deposit. • Calcite cathode luminescence intensity is controlled by Fe, Mn and ∑REE content. Ore-stage calcite of Carlin-type gold deposit has the characteristics of medium-heavy rare earth enrichment. • The ore-forming hydrothermal fluid of Carlin-type is characterized by diversity and mixed. The Carlin-type gold deposits in the Youjiang Basin, SW China can be further classified into three sub-types; strata-bound, fault-controlled, and diabase-associated. The compositions and sources of the ore-forming fluids for each deposit type are evaluated using the texture of calcite by CL (Cathode luminescence), its chemistry by EMPA (Electron probe microanalysis) and LA-ICP-MS (Laser ablation inductively coupled plasma mass spectrometry), and its C-O isotopic compositions by SIMS (Secondary ion mass spectroscopy). The studied deposits are the stratabound Zimudang deposit, the fault-controlled Lannigou deposit, and the diabase-associated Badu deposit. Calcite in the Zimudang and Lannigou deposits formed at three different stages: pre-ore stage pore-filling and massive calcite (Cal 1), late-ore stage vein calcite (Cal 2) associated with realgar and pyrite, and post-ore stage vein calcite (Cal 3). Calcite in the Badu deposit formed in two stages: ore stage vein and replacement calcite (Cal 2) associated with pyrite and post-ore stage calcites (Cal 3). Calcite with brighter red CL color has higher Mn and lower Fe content than calcite with darker red CL color. Furthermore, the higher the total REE content, the brighter the CL color. The host rocks are characterized by light REE (Rare earth element) enrichments. In contrast, the ore stage calcite shows middle REE enrichments. The ore stage calcite has higher concentrations of Fe, Mn, Mg, Si and Sr, and lower concentrations of Cu, Sb and Zn than both the pre- and post-ore calcite. The ranges of carbon (PDB) and oxygen (SMOW) isotope compositions of calcite are from −11.29 to 6.89‰ and from 16.49 to 22.60‰ for the Zimudang deposit, from −13.31 to 2.80‰ and from 9.12 to 29.71 for the Lanningou deposit, and from −11.94 to 0.49‰ and from 10.51 to 18.97‰ for the Badu deposit. Generally, the ore stage calcite has a wider range of δ13C and δ18O values than the other stage calcite. The isotope data indicate that a deep crustal fluid was involved in the formation of all of these three deposits. Meteoric water containing abundant organic matter was also involved in the formation of the Badu deposit as well as the Zimudang deposit, whereas a basin brine was also involved in the formation of the Lanningou deposit. [ABSTRACT FROM AUTHOR]