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The Jinding deposit in the Lanping basin, southwest China, is the largest sandstone-hosted Zn deposit in the world and the second largest Zn-Pb deposit in China. However, questions related to the metal compositions and origin of the ore fluids remain. In this study, microthermometry and laser ablation-inductively coupled plasmamass spectrometry (LA-ICP-MS) were employed to determine the properties and compositions of individual fluid inclusions trapped in sphalerite and calcite. The results show that the fluid inclusions trapped in sphalerite and calcite have similar homogenization temperatures (79°–173°C with the majority 100°–130°C), salinities (10.3–29.1 wt % NaCl + CaCl2 equiv with the majority 24.5–27.4 wt % NaCl + CaCl2 equiv), and concentrations of alkali and alkali earth elements (e.g., Na, Ca, Mg, K, Sr, Ba, Li, Rb, and Cs). However, the concentrations of ore and associated metals (e.g., Pb, Sb, Ag, and Tl) in the fluid inclusions hosted by sphalerite are significantly higher than those hosted by calcite. Based on these observations, we propose that the sulfides including sphalerite were precipitated from a low-temperature, high-salinity, Ca-rich, metal-rich fluid, while the gangue minerals such as calcite crystallized subsequently from fluids depleted in metals due to prior precipitation of sulfides, and that the high salinities of the fluid inclusions are likely due to a combination of seawater evaporation and subsequent dissolution of evaporitic sequences during fluid percolation. The LA-ICP-MS analyses reveal that the fluid inclusions have K/Na, Rb/Na, and Cs/Na ratios within the range of modern basinal brines, and Li/Na, Ba/Na, and Ca/Na ratios share similar compositions with the ore fluids of basement interacted deposits in the world. The Jinding ore fluids contain ~200 to 650 ppm Pb, based on the data of fluid inclusions trapped in sphalerite. The estimated concentrations of Zn in the ore fluids are also very high at ~200 to 6,500 ppm. Our results reveal that anomalously metal rich fluids played a critical role in the formation of the giant Jinding sediment-hosted Pb-Zn deposit. We concur with the previous suggestion that sulfide precipitation at Jinding occurred when ascending metal-rich brines encountered an H2S-rich, Ca-rich fluid, which was produced by interaction of hydrocarbons with evaporites, in the cap of the Jinding dome.

Recently, the mineral potential of the area surrounding the granitic batholiths in the Nanling Range was highlighted by the discovery of a series of tungsten and tin deposits or occurrences hosted in or near the Penggongmiao and Guidong batholiths in southern Hunan Province, South China. However, the lack of high-precision geochronological data from these deposits has hampered the understanding of their ore genesis and further W-Sn exploration progress. Based on detailed geological investigations, we obtained precise Secondary Ion Mass Spectroscopy (SIMS) zircon U-Pb and muscovite Ar-Ar ages from the greisen-dominated Liuyuan tin deposit and Zhuyuanli tungsten deposit, which are located on the western margin of the Guidong batholith. The results show that the 40Ar/39Ar plateau age of muscovite (153.10 ± 0.96 Ma) from the Liuyuan tin deposit is consistent with the 40Ar/39Ar plateau age of muscovite (151.64 ± 0.96 Ma) from the Zhuyuanli tungsten deposit within analytical error. These data indicate that the W-Sn mineralization in the region occurred during the Late Jurassic, which is significantly later than the emplacement of the Caledonian (Early Paleozoic) ore-hosting Guidong granite batholith, as evidenced by the SIMS zircon U-Pb age data from the Liuyuan greisen (438.1 ± 2.6 Ma) and the Zhuyuanli greisenized granite (433.8 ± 3.1 Ma). The remarkable differences in age between the Guidong batholith emplacement and formation of these two W-Sn ore deposits indicate that the regional tungsten and tin mineralization is temporally and genetically associated with possibly concealed Late Jurassic granite at depth rather than with the surrounding Caledonian granite batholith. The uniform W-Sn mineralization age (153–151 Ma) of the Liuyuan and Zhuyuanli deposits suggests that significant Late Jurassic W-Sn ore-forming potential exists along the western margin of the Guidong batholith.

The Nanling Range, South China, was world-famous for hosting abundant granitoid-related copper-lead-zinc (Cu-Pb-Zn) polymetallic ore deposits and quartz vein-type wolframite (W) ore deposits, both of which have roughly similar formation ages predominately between 150 and 160 Ma with a peak of ca. 156 Ma. In this study, accessory minerals from typical Cu-Pb-Zn-bearing and W-bearing granitic rocks are compared in terms of elemental and isotopic compositions. Apatite from W-bearing granites in the Xihuashan pluton has lower eNd(t) value (−11.9 to −8.6) than that from Cu-Pb-Zn-bearing granitic rocks in Shuikoushan with eNd(t) value of −8.7 to −4.2 and initial 87Sr/86Sr ratio of 0.7097–0.7109. Zircon grains in Xihuashan, yielded eHf(t) value from −14.9 to −11.4, δ18O value from 8.6‰ to 10.4‰, and highly variable and negative δ7Li value (−45.8‰ to −3.8‰), whereas those in Shuikoushan have relatively higher eHf(t) value (−10.6 to −8.1), lower δ18O value (8.4‰–9.7‰), and highly variable δ7Li values from −12.7‰ to +17.6‰. In situ Hf-O-Li isotopic compositions of zircon and Sr-Nd isotopes of apatite, suggesting that the Shuikoushan granitic pluton was likely generated from dehydration melting of amphibolite from a metal-fertile mafic source in the middle-to-lower crust, whereas the Xihuashan granitic pluton could be derived from partial melting of metapelite with minor amphibolite in the middle to upper crust. The geochemical records in accessory minerals fingerprint that the Shuikoushan granitic magma was characterized by high Cl content (0.11–1.44 wt%) and logfo2 value (>ΔFMQ+1), whereas the Xihuashan granitic magma have elevated F (3.51–4.80 wt%) and Li (3.49–42.4 ppm) contents with low logfo2 value (

The Lanuoma and Cuona sediment-hosted Pb-Zn deposits hosted by Upper Triassic limestone and sandstone, respectively, are located in the Changdu area, SW China. Mercury concentrations and Hg isotopic compositions from sulfide minerals and potential source rocks (e.g., the host sedimentary rocks and the metamorphic basement) were investigated to constrain metal sources and mineralization processes. In both deposits, sulfide minerals have higher mercury (Hg) concentrations (0.35 to 1185 ppm) than the metamorphic basement rocks (0.05 to 0.15 ppm) and sedimentary rocks (0.02 to 0.08 ppm). Large variations of mass-dependent fractionation (3.3‰ in δ202Hg) and mass-independent fractionation (0.3‰ in Δ199Hg) of Hg isotopes were observed. Sulfide minerals have Hg isotope signatures that are similar to the hydrothermal altered rocks around the deposit, and similar to the metamorphic basement, but different from barren sedimentary rocks. The variation of ∆199Hg suggests that Hg in sulfides was mainly derived from the underlying metamorphic basement. Mercury isotopes could be a geochemical tracer in understanding metal sources in hydrothermal ore deposits.

The Mesozoic Shuikoushan granitoid intrusion in the Jiangnan orogen between the Yangtze and the Cathaysia blocks in southern Hunan Province, South China, provides an opportunity to probe deep-crustal composition and structure, and to investigate the geodynamic evolution of South China. The intrusion is composed of granodiorite with I-type geochemical affinities and contains zircon with an U–Pb concordant age of 158.3 ± 1.2 Ma. Rocks from the intrusion have variable SiO2 from 58.4 wt.% to 65.2 wt.%, Al2O3 from 15.0 wt.% to 17.2 wt.%, TiO2 from 0.57 wt.% to 0.76 wt.%, and P2O5 from 0.27 wt.% to 0.52 wt.%. They have A/CNK from 0.97 to 1.23 (1.04 on average) and are dominantly peraluminous. They are characterized by enrichment in LREE ([La/Sm]N = 3.47–5.19) and LIL (e.g., K, Rb) and depletion in HFSE (e.g., U, Th) in primitive mantle normalized trace element diagrams. These geochemical features indicate that the rocks are I-type granodiorites and have undergone extensive fractional crystallization of hornblende, biotite, titanite, and apatite. All samples show negative eHf(t) (−10.6 to −8.1) and eNd(t) (−5.92 to −6.13) values, with relatively high initial 87Sr/86Sr (ISr) (0.7101–0.7102) and δ18O ratios (8.4–9.7‰). These values significantly differ from mantle values, suggesting that they are generated by the amphibole-dehydration melting of a mafic source in the middle-to-lower crust beneath the Jiangnan orogen. The emplacement of the Shuikoushan granitoid intrusion is contemporaneous with the late Jurassic to early Cretaceous extension within the Shi-Hang rift zone, indicating that it may have been formed under an extensional regime in response to both the Pacific superplume activity and westward subduction of the Pacific Plate. The extensional processes along with asthenosphere upwelling and basaltic underplating may have triggered the widespread late Jurassic granitoid intrusion in southern Hunan Province and possibly in South China.

The Shuikoushan ore district, located in southern Hunan Province, South China, contains Pb–Zn–Au mineralization hosted in the Devonian to Triassic strata and Mesozoic granodiorite intrusions. Ore minerals are mainly pyrite, sphalerite, galena and minor molybdenite. Molybdenite, usually intergrown with pyrite, formed during Pb–Zn hydrothermal mineralization. In order to determine the precise age of Pb–Zn mineralization and further understand the relationship between magma emplacement and hydrothermal mineralization in the ore district, molybdenite Re–Os dating and zircon SIMS U–Pb dating were undertaken. The zircon U–Pb dating reveals that the granodiorite intrusion was emplaced at 158.8 ± 1.8 Ma (MSWD = 0.40). Re–Os isotopic age of seven molybdenite samples yields model ages ranging from 157.5 ± 2.5 Ma to 161.0 ± 2.4 Ma, and gives a well-defined 187Re–187Os isochron age of 157.8 ± 1.4 Ma (2σ, MSWD = 1.3), indicating the timing of Pb–Zn mineralization in the Shuikoushan ore district at about 158 Ma. This date coincides well with the zircon SIMS U–Pb age of the granodiorite, revealing a genetic association between the Pb–Zn mineralization and the granitic magmatism. Combined with geochronological data published for other Pb–Zn–(Cu) deposits in southern Hunan, it can be concluded that the granodiorite-related Pb–Zn mineralization throughout southern Hunan mainly occurred at 160–156 Ma, rather than 180–170 Ma or 170–160 Ma as considered previously. The Pb–Zn mineralization and major W–Sn mineralization in southern Hunan are coeval and may be related to the same geological event.

The Woxi Au–Sb–W deposit, hosted by the Neoproterozoic low-grade metamorphic clastic rocks, is located in a brittle-ductile shear zone within the Xuefengshan Range, South China. Orebodies are predominantly banded quartz veins, which are strictly controlled by bedding faults and display significant vertical extents (up to 2 km) without obvious vertical metal zoning. Fluid inclusions hosted in quartz, scheelite, and stibnite from quartz–scheelite and quartz–sulfide–gold veins have been studied using conventional and infrared microscopy, respectively. Four types of fluid inclusions were identified based on petrography, including type I (two-phase, liquid-rich aqueous inclusions), type II (two- or three-phase, CO 2 -rich inclusions), type III (two-phase, vapour-rich aqueous inclusions), and type IV (single-phase aqueous inclusions). The fluid inclusions in ore minerals (scheelite and stibnite) and their coexisting quartz largely share similar characteristics in terms of their types, homogenization temperatures and salinities. This is consistent with the fact that these ore minerals are always intergrown with quartz. Microthermometric and laser Raman data indicate a low-to-moderate temperature (140–240 °C), low salinity ( 2 -rich, N 2 -bearing aqueous ore-forming fluid. Such fluid is further identified as a deeply non-magmatic crustal fluid rather than a mantle-source fluid by the significantly low 3 He/ 4 He ratios (0.002–0.281 Ra), and a small amount of meteoric water or host-rock-buffered fluid could be involved. W ore precipitation was probably associated with mixing between a deeply-originated crustal fluid and host-rock-buffered fluid based on the fluid inclusion features in scheelite and quartz-I. However, Au and Sb ore deposition probably resulted from boiling which was caused by the marked pressure drop. Geological features (such as banded structure and crack-sealing structure) also indicate that fluid pressure fluctuation induced by fault-valve mechanism occurred during ore precipitation. These characteristics of the ore-forming fluids in the Woxi deposit are in good agreement with the definition of orogenic gold deposits and the Woxi Au–Sb–W deposit is probably an atypical orogenic gold deposit for its unique ore-forming element association.

Lead–zinc–copper (Pb–Zn–Cu) deposits in the western Kunlun Orogen of China are mostly distributed along the Keziletao–Kusilafu fault zones in the Palaeozoic clastic–carbonate rocks, which formed in a late Palaeozoic subsidence belt at the south-west margin of the Tarim platform. Geological and geochemical studies were conducted on these deposits including detailed field observation, petrographic study, and geochemical and isotopic analyses of sulfur, lead, strontium, rhenium–osmium, and argon isotopes, as well as fluid inclusion geochemistry. The characteristics of the deposits include: (1) Except for the Tiekelike Pb–Cu deposit associated with mid-Devonian rocks, all of the other deposits were developed in the lower layers of the early Carboniferous strata. These strata mostly comprise sedimentary dolomitic limestone, sandy limestone, black limestone, and calcareous shale. (2) The ore bodies are stratiform and host veins. The stratiform ores are coeval with host rocks (yielding ore-forming ages of 331–337 Ma), while the vein ore bodies are mostly massive deposits formed at 206–235 Ma. The isotopic compositions of the sulfur and lead reveal that the ore-forming elements originated from various sources. (3) The mineralization in cements of brecciated ore is a veinlet type, while in the breccias it is a disseminated type. The stratoid, disseminated, and framboidal structures of the ore reveal the synsedimentary ore-formation. However, the veins, mesh-veins, and massive structures indicate late stage hydrothermal mineralization. (4) The principal metallic minerals include sphalerite, galena, and pyrite, while the secondary oxide minerals include variable distributions of cerussite, anglesite and limonite. The gangue minerals include dolomite, calcite, quartz, sericite, and gypsum, with minor chert and barite. (5) The original host rocks likely experienced dolomitization, calcitization, and minor silicification. The ore deposits underwent hydrothermal alterations, sub-greenschist facies metamorphism, and brecciation. The ore deposits may have initially formed via syndeposition in a subsidence belt along the southwest margin of the late Paleozoic Tarim platform; these deposits were further modified during later hydrothermal alteration and orogenesis during the Triassic period.

The Xuebaoding deposit in the Songpan–Garze orogenic belt, western China, spatially associated with the Xuebaoding granitic complex, is a unique pegmatite-type Sn–W–Be deposit within the giant Songpan–Garze polymetallic belt. A lack of precise geochronological constraints on the timing of mineralization for this deposit has precluded definitive statements relating to a genetic link between ore formation and granitoid intrusion, up to now. To address the temporal relationship between the emplacement of granite and the spatially associated Sn–W–Be polymetallic mineralization in the Xuebaoding deposit, systematic cassiterite U–Pb and muscovite Ar–Ar dating were undertaken. U–Pb data of cassiterite analyzed by In-situ LA-MC-ICP-MS provided an isochron age of 193.6 ± 6 Ma (at 95% confidence level, MSWD = 4). The 40 Ar/ 39 Ar dating on the muscovite intergrown with the cassiterite sample yielded a plateau age of 194.50 ± 1.02 Ma (MSWD = 1.26), and an inverse isochron age of 194.53 ± 1.05 Ma (MSWD = 1.34). Both the Ar–Ar dates overlap the U–Pb date within uncertainties, placing the timing of tin mineralization at ~ 193–194 Ma. This is consistent with field geological relationships that show veins cutting marble and granite, and with previous Sm–Nd dating, within experimental error, for scheelite and indicates that Sn–W polymetallic mineralization at the Xuebaoding deposit occurred during the Early Jurassic. Combined with previous published trace element and REE data from the Xuebaoding granites and other ore minerals, as well as the timing of granite emplacement, the temporal and genetic associations between granite intrusion events and Sn–W mineralization of this deposit have been discussed in this paper. The results suggest that the Pankou granite is genetically related to the polymetallic mineralization in Xuebaoding Sn–W–Be deposit, and further demonstrate that the latest-phase of granitic intrusion is commonly favorable for Sn and/or W mineralization. Although the Pukou granite also exhibits close relationships with the ore formation in its spatial distribution and element characteristics, the possibility as a parent for this deposit is excluded duo to the time span from its emplacement to mineralization event that exceed the estimated life of modern geothermal systems (

The Xihuashan tungsten deposit, hosted in the late Jurassic granitic pluton in the Nanling Range of South China, has a total resource of about 81,300 tonnes of WO3 with an average ore grade of 1.08% WO3. Wolframite is the dominant ore mineral and intergrown with quartz in the main mineralization stage. Ore-forming fluids trapped in wolframite have δD and δ18O values from −82‰ to −64‰ and 7.4‰ to 8.8‰, respectively. Those in quartz have similar δD (−72‰ to −58‰) and δ18O (6.8‰ to 8.0‰) values, indicative of a magmatic fluids simultaneously trapped by quartz and wolframite. LA-ICP-MS analyses for individual fluid inclusion show that this mineralizing fluid contains measurable Li, Rb, Cs, K, Na, Ti, Cu, Zn, As and W (1–125 ppm with average of 19 ppm) while depleted in Fe and Mn. The wolframite from the Xihuashan tungsten deposit contains high FeO (10.9–17.7 wt%) and MnO (5.9–12.7 wt%) contents with Fe/(Fe + Mn) atomic ratio of 0.46 to 0.75, thus requires the availability of external Fe and Mn. We detect that the Fe and Mn contents in mica from the greisen are remarkably lower than primary mica from granite. Some magmatic micas were observed in greisen and were subjected to hydrothermal alteration. Compared to the core, the rim of these micas depleted in Fe, Mn, F, and Na. The siderite and pyrophanite are formed along cleavage planes of altered magmatic mica that are evidence to be due to Fe and Mn release during granite alteration. Thus, we demonstrate quantitatively that magmatic fluids at Xihuashan provide W in solution, whereas the hosted granite alteration contributes Fe and Mn to precipitate wolframite. It is also supported by wolframites have trace and rare earth elements characteristics similar to those of granite and some characteristics similar to the greisen. Therefore, the ore-forming fluids has components derived from the last highly evolved residual granitic melt and components acquired by releasing through the hosted granite alteration. Fluid-rock interaction exert a principle control on wolframite precipitation. Based on mineralogy, fluid inclusion and stable isotope, we proposed three-stage process to illustrate the genetic link between tungsten mineralization and granite.

The Lanuoma deposit, located in the Sanjiang Tethyan metallogenic domain, shows a characteristic assemblage of Pb-Zn-Sb mineralization, distinguished from those in other sediment-hosted base metal deposits of this region. The ore textures reveal two mineralization stages: the early stage is characterized by Zn mineralization with occurrences of porous pyrite (Py2) and yellowish-brown sphalerites (Sp1), and the late stage is characterized by Sb-Pb mineralization with occurrences of subhedral-euhedral pyrite (Py3), yellowish-white sphalerites (Sp2), sulfosalts consisting of boulangerite, zinkenite, sorbyite and plagionite and calcite veins. The framboidal pyrites (Py1) predate Pb-Zn-Sb mineralization. Py2 has higher Zn contents (16.97–621.67 ppm, mean: 181.17 ppm) than Py3 (Zn: 0.76–323.44 ppm, mean: 29.58 ppm) by up to one order of magnitude. The Se contents of Py2 (Se: 5.46–87.82 ppm, mean: 50.96 ppm) are also one order of magnitude higher than those of Py3 (Se: 1.64–10.99 ppm, mean: 4.35 ppm). Sp1 is characterized by one order of magnitude higher contents of Fe (381.99–9046.64, mean: 4875.50 ppm) and Se (4.02–72.51 ppm, mean: 34.70 ppm) than Sp2 (Fe: 287.53–584.02 ppm, mean: 416.75 ppm; Se: 2.89–10.80 ppm, mean: 6.20 ppm). However, the average content of Cd (4256.38 ppm) in Sp2 is almost twice that in Sp1 (2635.74 ppm). The higher Se contents in Py2 coupled with higher Se and Fe contents in Sp1 indicate that Py2 and Sp1 had higher precipitation temperatures than Py3 and Sp2. Sulfur isotope compositions of pyrites and sphalerites acquired by NANO-SIMS and LA-MC-ICP-MS suggest two origins: the sulfur of Py2 (δ34S: −3.0 to 2.3‰), Sp1 (δ34S: 0.2–0.9‰) and Sp2 (δ34S: 0.7–2.5‰) was mainly of magmatic source, and sulfur reduced via thermochemical sulfate reduction participated in the formation of Py3 (δ34S: 0.2–6.0‰) and S-Sb-Pb minerals intergrown with Py3. The sulfur isotope compositions of Py1 (δ34S: −31.8 to −19.4‰) indicate a biogenic origin associated with bacterial sulfate reduction. A fluid mixing model is suggested to interpret the genesis of the Lanuoma Pb-Zn-Sb deposit: mixing of a reduced S-bearing fluid with a metalliferous basinal brine resulted in the precipitation of sulfides. Temperature was the most important factor controlling metal precipitation in the Lanuoma deposit.

The Xihuashan complex intrusion in South China, which is emplaced at ca. 154 Ma, mainly comprises medium-grained porphyritic biotite granite, medium-grained biotite granite, and fine-grained two-mica granite. Medium-grained biotite and fine-grained two-mica granites are important tungsten-bearing granites and contain an unusual amount of garnet. Garnets from this intrusion are dominated by almandine and spessartine, which constitute 94% to 99% of the total molecular composition of the garnet. These garnets display unusual compositional zoning. The cores of these garnets are rich in heavy rare earth element (HREE), Y, Ca, and contain abundant HREE- and Y-rich mineral inclusions. Their rims are free of mineral inclusions and have low of these elements. Two types of fluorite inclusions exist in garnet: Y fluorite and Y-poor fluorite. Garnet exhibits specific Mn zoning with a relatively Mn-poor core but a relatively Mn-rich rim, thus constituting a specific “spessartine inverse bell-shaped profile” that belongs to typical magmatic garnets. All analyzed garnets have high REE content and exhibit HREE-enriched and LREE-depleted patterns with strong negative Eu anomalies. The incorporation of REE into garnet is in part controlled by its crystal chemistry, with REE3 + following a coupled substitution of the type [Fe2 +,Mn2 +]− 1VIII[REE3 +]+ 1VIII[Si4 +]− 1IV[Z3 +]+ 1IV. The texture and compositional zoning of garnet suggest that garnet growth is largely controlled by the pressure–temperature–composition condition of magmatic evolution, internal crystal-chemical parameters, and kinetics during mineral growth. The garnet core grows in near equilibrium with magmatic melt under a relatively high pressure–temperature (P–T) condition. By contrast, the garnet rim grows rapidly by the coexisting melt-fluid phase and CO2-rich volatile environment under a relatively low P–T condition, which is virtually unfavorable for the incorporation of REE into the magmatic garnet structure. Garnet fingerprints the magmatic-hydrothermal transition during crystallization of these granites.

The Xihuashan tungsten deposit in the central Nanling region, South China, is an important vein-type ore deposit hosted in Cambrian strata and Mesozoic granitic intrusions. Wolframite and molybdenite are the principal ore minerals. The gangue minerals are mainly quartz and muscovite. Wolframite and molybdenite are products of the first stage hydrothermal activity, whereas muscovite formed dominantly at the second stage. Molybdenite Re–Os and muscovite 40Ar/39Ar dating have been carried out to investigate the age of mineralization. Re–Os isotopic dating for molybdenite associated with wolframite yield a precise, well-constrained isochron age of 157.8 ± 0.9 Ma (MSWD = 1.5). Ar–Ar isotopic analyses of muscovite yield a plateau age of 152.8 ± 1.6 Ma, in agreement with an inverse isochron age of 152.8 ± 1.6 Ma, which is ~ 5 mys younger than the Re–Os age. The molybdenite Re–Os age is interpreted as the age of tungsten mineralization. This age coincides well with the zircon U–Pb age of the host granitic intrusion reported previously. The ~ 5 mys difference between molybdenite Re–Os and muscovite 40Ar/39Ar ages probably represents the duration of hydrothermal activity. The results show that the Xihuashan tungsten deposit is one of many important tungsten–tin deposits formed during 150 to 160 Ma associated with large-scale lithospheric extension in South China.

Northern Guangdong is an important part of Nanling tungsten–tin metallogenic belt, South China. The tungsten mineralization in this area consists of mainly quartz–wolframite vein-type mineralization, with W–Sn polymetallic deposits mostly distributed at the outer contact zone between concealed Late Jurassic granitic stocks and Cambrian–Ordovician low-metamorphosed sandstones and shales. Molybdenite Re–Os and muscovite 40Ar/39Ar isotopic dating of three typical tungsten vein-type deposits (Yaoling, Meiziwo, and Jubankeng) in northern Guangdong, show that two episodes of Late Jurassic W–Sn polymetallic mineralization occurred in this area: an early episode during the Late Jurassic (158–159 Ma) represented by the Yaoling, Hongling, and Meiziwo tungsten deposits, and a younger event during the Early Cretaceous (138 Ma) represented by the Jubankeng deposit. Analysis of available radiometric ages of several W–Sn deposits in the Nanling region indicate that these deposits formed at several intervals during the Mesozoic at 90–100, 134–140, 144–162, and 210–235 Ma, and that large-scale W–Sn mineralization in this region occurred mainly between 150 and 160 Ma.

More than 90% of the tungsten resources of China are in the Nanling region of South China, and the Yaogangxian vein deposit is the largest tungsten deposit in this region. The tungsten deposits have ages of 150–160 Ma, and are spatially, temporally and genetically related to granites which were previously believed to be produced by crustal anatexis. This paper provides He and Ar isotope data of fluid inclusions in pyrite and arsenopyrite from the Yaogangxian W veins. 3He/4He ratios range from 0.41 to 3.03 Ra (where Ra is the 3He/4He ratio of air = 1.39 × 10−6), and 40Ar/36Ar ratios from 328 to 1,191. Moreover, there are excellent correlations between He and Ar isotopic compositions. The results suggest that the ore-forming fluids are a mixture between a crustal fluid containing atmospheric Ar and crustal 4He and a fluid containing mantle components. It is likely that the former is a low temperature meteoric fluid, and the later is a fluid exsolved from the W-associated granitic magma, which formed by crustal melting induced by intrusion of a mantle-derived magma.

The Xihuashan tungsten deposit, Jiangxi province, China, is a world-class vein-type ore deposit hosted in Cambrian strata and Mesozoic granitic intrusions. There are two major sets of subparallel ore-bearing quartz veins. The ore mineral assemblage includes wolframite and molybdenite, with minor amounts of arsenopyrite, chalcopyrite, and pyrite. There are only two-phase aqueous-rich inclusions in wolframite but at least three major types of inclusions in quartz: two- or three-phase CO2-rich inclusions, two-phase pure CO2 inclusions and two-phase aqueous inclusions, indicating boiling. Fluid inclusions in wolframite have relatively higher homogenization temperatures and salinities (239–380°C, 3.8–13.7 wt.% NaCl equiv) compared with those in quartz (177–329°C, 0.9–8.1 wt.% NaCl equiv). These distinct differences suggest that those conventional microthermometric data from quartz are not adequate to explain the ore formation process. Enthalpy–salinity plot shows a linear relationship, implying mixing of different sources of fluids. Although boiling occurred during vein-type mineralization, it seems negligible for wolframite deposition. Mixing is the dominant mechanism of wolframite precipitation in Xihuashan. δ34S values of the sulfides range from −1.6 to +0.1‰, indicative of a magmatic source of sulfur. δ18O values of wolframite are relatively homogeneous, ranging from +4.8‰ to +6.3‰. Oxygen isotope modeling of boiling and mixing processes also indicates that mixing of two different fluids was an important mechanism in the precipitation of wolframite.

The Shizhuyuan ore deposit in southern Hunan Province is a world-class W–Sn–Bi–Mo occurrence hosted by Devonian limestone in the thermal aureole of the Qianlishan granite. Mineralization coincided with intrusion of the granite pluton during Mesozoic crustal extension in South China. We present new He and Ar isotope data for volatiles released from pyrite in the Shizhuyuan deposit. Concentrations of 40Ar range from 0.21 to 2.38 × 10−6 cm3 STP 40Ar/g, and 4He concentrations range from 0.8 to 65.1 × 10−6 cm3 STP 4He/g. 3He/4He ratios vary from 0.06 to 1.66 Ra (where Ra is the 3He/4He ratio of air = 1.39 × 10−6) and 40Ar/36Ar ratios range from 293 to 1072. The isotopic compositions of He and Ar indicate that the ore-forming fluids were mantle-derived, modified by air-saturated crustal fluids. Shallow-level boiling increased 3He concentrations, whereas crustal contamination decreased 3He/4He ratios in the magmatic fluids. The occurrence of mantle-derived components in the magmatic fluid indicates that the asso...

The Xujiashan antimony deposit is hosted by marine carbonates of the Upper Sinian Doushantuo and Dengying Formations in Hubei Province, South China. Our Sr isotopic data from pre- and syn-mineralization calcites that host the mineralization show that the pre-mineralization calcite displays a narrow range of 87 Sr/ 86 Sr ratios (0.7096 to 0.7097), similar to the ratios of the Sinian seawater, and high Sr concentrations (2645 to 8174 ppm). In contrast, the syn-mineralization calcite exhibits low Sr concentrations (785 to 2563 ppm) and high 87 Sr/ 86 Sr ratios (0.7109 to 0.7154), which is interpreted as the result of addition of radiogenic strontium during the antimony mineralization. The study of Sr isotopes suggests that their Sr component to the pre-mineralization calcite derived directly from the host rocks (i.e. the Sinian marine carbonates), while radiogenic 87 Sr for the syn-mineralization calcite derived from the underlying Mesoproterozoic Lengjiaxi Group basement through hydrothermal fluid circulation along the major fault that hosts the mineralization. The Pb isotopic ratios of stibnite are subdivided into two groups (Group A and Group B), Group A is characterized by higher radiogenic lead, with 206 204 Pb/

The Furong tin deposit in the central Nanling region, South China, consists of three main types of mineralization ores, i.e. skarn-, altered granite- and greisen-type ores, hosted in Carboniferous and Permian strata and Mesozoic granitic intrusions. Calcite is the dominant gangue mineral intergrown with ore bodies in the orefield. We have carried out REE, Mn, Fe, and Mg geochemical and C, and O isotopic studies on calcites to constrain the source and evolution of the ore-forming fluids. The calcites from the Furong deposit exhibit middle negative Eu anomaly (Eu/Eu*= 0.311–0.921), except for one which has an Eu/Eu* of 1.10, with the total REE content of 5.49–133 ppm. The results show that the calcites are characterized by two types of REE distribution patterns: a LREE-enriched pattern and a flat REE pattern. The LREE-enriched pattern of calcites accompanying greisen-type ore and skarn-type ore are similar to those of Qitianling granite. The REE, Mn, Fe, and Mg abundances of calcites exhibit a decreasing tendency from granite rock mass to wall rock, i.e. these abundances of calcites associated with altered granite-type and greisen-type ores are higher than those associated with skarn-type ores. The calcites from primary ores in the Furong deposit show large variation in carbon and oxygen isotopic compositions. The δ13C and δ18O of calcites are −0.4 to −12.7‰ and 2.8 to 16.4‰, respectively, and mainly fall within the range between mantle or magmatic carbon and marine carbonate. The calcites from greisen and altered granite ores in the Furong deposit display a negative correlation in the diagram of δ13C versus δ18O, probably owing to the CO2-degassing of the ore-forming fluids. From the intrusion to wall-rock, the calcites display an increasing tendency with respect to δ13C values. This implies that the carbon isotopic compositions of the ore-bearing fluids have progressively changed from domination by magmatic carbon to sedimentary carbonate carbon. In combination with other geological and geochemical data, we suggest that the ore-forming fluids represent magmatic origin. We believe that the fluids exsolved from fractionation of the granitic magma, accompanying magmatism of the Qitianling granite complex, were involved in the mineralization of the Furong tin polymetallic deposit.

In this paper the authors present the REE concentrations and Sr and Nd isotopic compositions of fluorites from the Bailashui tin deposit of the Furong ore field, southern Hunan Province. The results showed that the total amount of REE in fluorites is usually low, ranging from 0.705 to 8.785 μg/g with the chondrite-normalized REE distribution patterns similar to those of the Qitianling granites in the study area, characterized by LREE-enrichment patterns with pronounced negative Eu anomalies. The fluorites vary in Sr isotopic composition within the range of 0.7083–0.7091, the values are lower than those of the granites and higher than those of the host carbonate rocks in this area. The ɛNd(t) values of fluorites vary between −9.4 and +10.3, revealing that both the crust-and mantle-source materials were involved in the ore-forming hydrothermal fluids. Combined with previous studies on this ore deposit, the Bailashui tin deposit is temporally and spatially closely related with granitic magmatism in this area. The hydrothermal fluorites are the product of fluid/rock interactions between granitic magmatic hydrothermal fluid and marine carbonate rocks. The REE and F in the ore-forming fluid were derived from the granites, whereas Sr in the ore-forming fluid came mainly from the granitic magmatic hydrothermal fluid and marine carbonate rocks, although variations in Sr isotopic composition cannot be explained by a simple mixture of these two end-members. Evidence demonstrated that the ore-forming fluids are of crustal-mantle mixing origin, but that the fluids were probably incompletely homogenized and this may be caused by inhomogeneous mixing of the fluids of different sources.

South China is rich in vein-type hydrothermal uranium deposits hosted in granitic, volcanic, and carbonaceous and siliceous pelitic sedimentary rocks. The uranium deposits are spatially associated with extensional structures and/or mantle-derived mafic dikes. Both the uranium deposits and mafic dikes are Cretaceous to Tertiary in age, temporally coincident with the crustal extension. Carbon isotope analyses of calcite deposited in the main-stage mineralization in the veins from 12 representative uranium deposits yield δ13C values of ore-forming fluids mainly from −4 to −8 per mil, which are permissive of a mantle origin for the CO2 in the ore-forming fluids. A mantle origin is consistent with the association of the deposits with mafic dikes and the 3He/4He ratios of ore-forming fluids (e.g., 0.10–2.02 Ra for the volcanic-hosted Xiangshan uranium deposit). Isotopic compositions of H and O demonstrate that water in the ore-forming fluids is predominantly meteoric in origin. Ore-forming temperatures ranged approximately from 150° to 250°C. Uranium-rich crustal rocks in South China may have been the sources for the uranium. Crustal extension and associated mafic magmatism are considered to have heated the rocks and allowed CO2 (possibly from mantle sources) to migrate upward and to mix with CO2-poor meteoric water. The CO2-rich hydrothermal fluids mobilized uranium from the source rocks and then the uranium was deposited in various host rocks to form the uranium deposits.

Geochemical and Sr–Nd–Pb isotopic data are presented for volcanic rocks from Zougouyouchaco (30.5 Ma) and Dogai Coring (39.7 Ma) of the southern and middle Qiangtang block in northern Tibet. The volcanic rocks are high-K calc-alkaline trachyandesites and dacites, with SiO2 contents ranging from 58.5 to 67.1 wt % The rocks are enriched in light REE (LREE) and contain high Sr (649 to 986 ppm) and relatively low Yb (0.8 to 1.2 ppm) and Y (9.5 to 16.6 ppm) contents, resulting in high La/Yb (29–58) and Sr/Y (43–92) ratios, as well as relatively high MgO contents and Mg no., similar to the compositions of adakites formed by slab melting in subduction zones. However, the adakitic rocks in the Qiangtang block are characterized by relatively low εNd(t) values (−3.8 to −5.0) and highly radiogenic Sr ((87Sr/86Sr)i=0.706–0.708), which are inconsistent with an origin by slab melting. The geochemistry and tectonics indicate that the adakitic volcanic rocks were most likely derived from partial melting of delaminated lower continental crust. As the pristine adakitic melts rose, they interacted with the surrounding mantle peridotite, elevating their MgO values and Mg numbers.

We report the first precise U–Pb isotope data on cassiterite from the large Xianghualing tin-polymetallic deposit in the central Nanling district, South China. The results show that four separates from sample XF-51 have a relatively narrow range of 206Pb/238U apparent ages, varying from 152 to 157 Ma, and the three 206Pb/238U apparent ages yield a weighted average value of 156 ± 4 Ma (MSWD = 0.32). Separates from two other cassiterite samples do not have sufficient radiogenic Pb to generate a reliable 206Pb/238U age. Seven separates from the above three cassiterite samples define a well-constrained 238U–206Pb isochron corresponding to an age of 157 ± 6 Ma (MSWD = 34). A comparison of the U–Pb cassiterite ages with published Ar–Ar dates on muscovite from this deposit and K–Ar age data on biotite from the pluton genetically related to the tin mineralization in this area demonstrates that the U–Pb isotope system of cassiterite is a potential geochronometer. Combined with the Ar–Ar dates of muscovite from this deposit, we can constrain the absolute age of tin-polymetallic mineralization in Xianghualing at 154–157 Ma. The dates obtained in this study, consistent with the published geochronological results from other important deposits in this region, reveal that the large-scale tungsten–tin mineralization in the central Nanling region was predominantly emplaced during 150–161 Ma.

The Furong tin deposit, located in southern Hunan Province, China, is a large, newly discovered deposit with an estimated Sn reserve of about 700,000 tons. The deposit is spatially and temporally associated with the A-type Qitianling granite. The 3He/4He ratios of fluid inclusions trapped in sulfides from the deposit range from 0.13 to 2.95 Ra, indicating a mixed crust-mantle source, similar to that of the Qitianling granite complex. Lead isotopes in feldspars of the granite (mostly in the range of 206Pb/204Pb = 18.547–19.180, 207Pb/204Pb = 15.598–15.825, 208Pb/204Pb = 37.912–39.068) and in sulfide minerals (206Pb/204Pb = 18.467–18.836, 207Pb/204Pb = 15.503–15.772, 208Pb/204Pb = 38.607–39.099) are essentially the same, indicating that the lead in both was derived mainly from the upper crust, with a small mantle component. The sulfur isotopic values of the ore minerals vary widely, ranging from − 26.1‰ to + 10.4‰, but are mainly within the range of + 0.2‰ to + 10.4‰, implying that the S in the hydrothermal fluids was derived mainly from magmatic fluids, with minor contributions from the mantle, sedimentary rocks and biogenic material. The He, Pb and S isotopes all confirm that the ore-forming fluids of the Furong deposit were magmatic in origin, derived from the melts that produced the Qitianling A-type granite. The tin mineralization occurs within, or along the margins of, the Qitianling granite complex, and the timing of the mineralization coincides with the intrusive age of the granite. The available data suggest that the emplacement of the granites and the mineralization was related to mantle upwelling and extension of the lithosphere in South China during the Mesozoic.

The Yaogangxian deposit in the central Nanling region, South China consists of vein-type ore bodies hosted in Cambrian to Jurassic strata and Mesozoic granitic intrusions. Wolframite and molybdenite are the dominant ore minerals intergrown with gangue minerals of quartz, feldspar, phlogopite, and muscovite. We have carried out molybdenite Re–Os and phlogopite and muscovite 40Ar/39Ar dating to better understand the timing and genesis of mineralization. Re–Os dating of eight molybdenite samples yielded model ages ranging from 152.0±3.5 to 161.1±4.5 Ma, with an average of 156.0 Ma. The Re–Os analyses give a well-defined 187Re/187Os isochron with an age of 154.9±2.6 Ma (MSWD=2.4). Hydrothermal phlogopite and muscovite display extremely flat 40Ar/39Ar age spectra. Phlogopite yields a 40Ar/39Ar plateau age of 153.0±1.1 Ma, whereas muscovite yields a plateau age of 155.1±1.1 Ma. Both 40Ar/39Ar ages are in good agreement with the Re–Os ages, placing the timing of tungsten mineralization at about 154 Ma. This age is consistent with the field relationships. Our new data, when combined with published geochronological results from other major deposits in this region, suggest that large scale W–Sn mineralization occurred throughout the central Nanling region in the Late Jurassic.

The Furong tin orefield, located in southern Hunan, China, is a newly-discovered super-large tin orefield. In contrast to most other tin deposits associated with S-type granites, the Furong tin deposit is closely associated with the Qitianling A-type granite. The 3He/4He ratios of fluid inclusions in pyrite and arsenopyrite from this orefield range from 0.13 to 2.95 Ra. The influence of various post-mineralization processes on the helium isotopic composition of ore-forming fluid inclusions are estimated negligible. Thus, the analytical values of helium isotopic composition basically represent the original values of ore-forming fluids at the time they were trapped. The 3He/4He ratios of ore-forming fluids from the Furong orefield indicate the existence of mantle-source components. It supports the idea that both the Furong tin orefield and Qitianling granite formed under the geodynamic background of mantle upwelling and crustal extension.

Alkali-rich intrusive rocks in western Yunnan were derived from an enriched lithospheric mantle (EM II) source. The data available indicated they are alkali-rich (K2O + Na2O > 8wt%) and shoshonitic. Although formed in a within-plate environment they exhibit signatures of arc magmatic rocks, such as high amounts of LILE and LREE relative to the HFSE and HREE, and thus high Ba/Nb, Ba/Zr, Sr/Y, La/Yb ratios as well as mimic chondrite-normalized REE and primitive mantle-normalized trace element patterns of subducted sediments, and they fall in the collision- or arc-related tectonic setting field on all discrimination diagrams. This might suggest the enrichment be related to the substantial extent of sediment contamination by the Mesozoic Tethyan subduction processes.

187Os/188Os ratios in all sub-layers of the Co-rich ferromanganese crust MP5D17 from Line Seamount in Central Pacific have been systematically determined. The 187Os/188Os values in this crust are highly variable, ranging from 0.4262 to 1.0155. From the bottom to the top, the osmium isotopic ratios of the crust display a regular variation trend, which correlates well with its changes in structure and texture in the vertical profile. In comparison with the evolution curve of Os isotopic composition in seawater over the past 80 Ma, a similar evolution tendency can be found with respect to the Os isotopic composition of the crust in this study. It is preliminarily concluded that the crust MP5D17 began to grow at about 72 Ma, and underwent three growth hiatuses, corresponding to the geological ages of 64, 53 and 37 Ma, respectively.

The Xikuangshan antimony mine located at Central Hunan, China, is the largest antimony deposit in the world. Hydrothermal calcites from the Xikuangshan Mine display relatively large variations in REE abundance and Sm/Nd ratios and are characterized by MREE- and HREE-enriched and LREE-depleted patterns. Sm–Nd isotopic compositions of syn-sulfide calcites fall on well-defined lines in the isochron plot. Calcites from early- and late-stage mineralization form two distinct isochrons corresponding to 155.5±1.1 and 124.1±3.7 Ma, respectively. The isochron ages suggest that Sb mineralization took place during the Late Jurassic–Early Cretaceous Period in the Xikuangshan district, consistent with previous geological observations and with independent isotope data. Samarium–neodymium dating of calcites shows potential for determining ages of hydrothermal mineralization.

Nine seamount ferromanganese nodules from six seamounts in the mid-Pacific Ocean have been sampled, the obtained sixteen sub-samples were used to analyze their main elements, trace elements and rare earth elements by the chemical method and ICP-MS, platinum group elements have also been analyzed for some subsamples, using the methods of Te co-precipitation pre-concentration and isotope dilution. All subsamples have been analyzed by X-ray diffraction for their mineral composition. It is shown from the analysis results that the mineral composition, chemical characteristics and the occurrence of main components of seamount nodules from mid-Pacific Ocean are similar to those of hydrogenous cobalt-rich crust on seamounts, which indicates that seamount nodules were hydrogenous. Compared with the ferromanganese nodules occurring on the surface of deep-sea sediments, seamount nodules have higher Fe and Co but lower Cu and Ni, so the seamount nodules from mid-Pacific Ocean might be formed on the surface of sediments on seamounts in weak acidic but strong oxidation environment. Because of their similar occurring depth and redox conditions, seamount nodules are very similar to cobaltrich crust in their chemical composition, minerals and occurrence of main compositions. However, having been found on the sediment-seawater interface, seamount nodules experienced the influence of early-diagenesis of sediments, so the typical seamount crust has some characteristics of transition to ferromanganese nodules.

Scheelite Sm-Nd and quartz Ar-Ar dating were accomplished for the Woxi Au-Sb-W deposit in western hunan. The results show that the Sm and Nd concentrations of scheelite are relatively high, and Sm/Nd ratios are usually high and variable. In the 147Sm/144Nd vs. 143Nd/144Nd diagram, the disseminated scheelites show a good linear array, which corresponds to an isochron age of 402 ±6 Ma and an initial 143Nd/144Nd ratio of 0.510544± 9 (2oσ) with a eNd(t) value of −30.7. The Ar-Ar age spectra for 2 quartz samples display the saddle shape. The minimum apparent age, plateau age and isochron age of each quartz sample generally overlap within errors; and both the minimum apparent ages of 420±20 and 414 ± 19 Ma coincide well with the scheelite Sm-Nd age. Both Sm-Nd and Ar-Ar dating results reveal that the Au-Sb-W mineralization at Woxi district took place in the Late Caledonian. This is in good agreement with the tectonic evolution of the Xuefengshan district and with some geochronological data available for Au, Sb and W deposits in this area. The low initial Nd isotope ratio of scheelites suggests that the fluid responsible for Au-Sb-W mineralization at the Woxi is of deep crustal origin and probably originated from the underlying Archaean continental basement rather than the host Proterozoic strata in western Hunan. The constraints on the mineralization time and on the fluid source provide insight into the genesis of the Woxi deposit.

The research on Samarium-Neodymium isotope systematics of hydrothermal calcites from the Xikuangshan antimony deposit, Central Hunan, places precise timing constraints on the Sb mineralization in this area. It is revealed that the Xikuangshan deposit formed during the late Jurassic-early Cretaceous Period, the early- and latestage mineralization took place at (155.5± 1.1) Ma and (124.1±3.7) Ma, respectively. The accurate age determination of mineralization is very crucial for revealing the super-enrichment mechanism of the element Sb at the Xikuangshan mine, and lays some foundations for the further understandings of its ore genesis and mineralization mechanism.