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Two types of turquoise, including homogeneous Cu-rich turquoise and oscillatory zoned turquoiseplanerite series, are recognized in association with quartz-barite veins hosted by Cambrian carbonaceous slates from western Hubei Province of China. Combined fluid inclusion and Raman micro-spectroscopic data reveal that turquoise-bearing barite-quartz veins contain three types of fluid inclusions (pure CH4-N2, carbonic-aqueous, and aqueous), suggesting the responsible fluid is of carbonic-aqueous composition with low oxygen fugacity. Pressure-corrected homogenization temperatures in quartz and barite show a range from 325 to 485 °C and 186 to 391 °C, respectively. Carbon, oxygen, and hydrogen isotopic data suggest that the mineral-forming fluids have a mixed metamorphic-organic affinity, in which the fluids have δ18O and δD values of 15.0 to 18.8‰ and –111 to –93‰, respectively. Generally, the formation of quartz-barite-turquoise veins could be triggered by prior metamorphic devolatilization, followed by the interaction of fluids with country rocks enriched in carbonaceous material, which resulted in the leaching of Cu, Fe, P, and Al from chalcopyrite, pyrite, magnetite, monazite, xenotime, apatite, feldspar, and muscovite in the wall rocks. Decomposition of the organic matter in the carbonaceous slates, caused by regional metamorphism and deformation, could also promote the concentration and transportation of necessary metals for the turquoise. Thus, we propose a new model and suggest that the turquoise gem deposits in western Hubei Province of China belong to the non-magmatic hydrothermal vein type deposit, not the previously proposed supergene origin. The turquoise-forming fluids were characterized by the coexistence of two immiscible fluids of non-magmatic affinity (i.e., moderate to high-temperature and low-salinity aqueous fluid and pure CH4-N2 fluid formed by interaction with carbonaceous slates). The bluish green homogeneous turquoise in the metamorphic quartz-barite-turquoise veins evolved toward the turquoise-planerite solid solution series as the metal-leaching capability of the aqueous fluids decreased. [ABSTRACT FROM AUTHOR]

The Wangjiadashan area in Suizhou-Zaoyang region of Hubei Province in the Tongbai-Dabie orogenic belt hosts important copper-gold deposits and contains a large number of quartz syenite porphyry dykes, occurring mostly along the NEE-trend faults. In this study, we used LA-ICP-MS zircon U-Pb dating method and obtained an age of 143.6 ± 1.4 Ma, which represents the emplacement of these quartz syenite porphyry dykes was at the Yanshanian, but it was slightly earlier than the previously reported ages (139–135 Ma) for granites widespreading in Suizao area. The geochemical data of the Wangjiadashan quartz syenite porphyry show high K2O, CaO, Na2O and Al2O3 contents but extremely low MgO contents (0.01 wt.%–0.46 wt.%). The geochemical characteristics indicate that these quartz syenite porphyry dykes belong to the typical C-type adakite and were possibly formed in the post-collisional environment. Multi-isotopic (Sr-Nd-Pb-Hf) analyses indicate that these quartz syenite porphyry dykes were originated from crust without distinct mantle materials involved. It is suggested that the Wangjiadashan quartz syenite porphyry was generated from partial melting of the thickened lower continental crust, and garnet but no plagioclase was left as residual phase. Compared with the widespread granites of the Tongbai area, the Wangjiadashan quartz syenite porphyry formed earlier and derived from more juvenile and K-rich lower crust, while they all belong to intensive magmatism concentrated during the Early Cretaceous epoch in the Tongbai area. [ABSTRACT FROM AUTHOR]

The Huangling gold deposits belong to orogenic gold deposits, forming during the tectonic transformation period at ca. 830–800 Ma. [Display omitted] • Gold mineralization in the Huangling region occurred ca. 830-800 Ma. • The timing of gold mineralization coincided with the tectonic transformation period. • The Huangling gold deposits belong to orogenic gold deposits. The Huangling region of northwestern Hubei Province, which contains 76 gold deposits with more than 310 gold-quartz veins, is located in the northern part of the Yangtze Craton, South China Block. Despite several geological and geochronological studies conducted on gold deposits in this region, the timing and origin of gold mineralization remain controversial. This study utilizes in situ U–Pb dating of apatite and monazite from representative ores from the Banchanghe, Hongwucun, and Sunjiahe gold deposits to determine the timing of gold mineralization. The results indicate that gold mineralization occurred ca. 830–800 Ma, which is consistent with the period of tectonic transformation in the region. This study proposes that the gold deposits in the Huangling region represent typical orogenic gold deposits. These findings indicate a rare example of a well-preserved early Neoproterozoic orogenic gold system, suggesting the existence of orogenic gold deposits during the growth of the Rodinia supercontinent. This study highlights the significant potential for further exploration in the deep of the Huangling region to uncover additional gold veins. These findings also suggest that the Neoproterozoic orogenic belts of the Yangtze Craton may serve as important targets for gold deposit exploration in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new type clay-Li deposit is found in southern Hubei Province, China. • This deposit was formed by fault-controlled hydrothermal alteration. • Hydrothermal apatite U-Pb dating indicates an age of 135.2 ± 13.9 Ma. • The Li enrichment is related to the Mufushan granitic magmatism. Clay-Li deposits are among the major Li deposits in the world and occur mainly in sedimentary and/or volcanic-sedimentary strata. The Li orebodies are generally stratiform and stratibound, and Li is mainly hosted in various clay minerals. Here, we report a new type of clay-Li deposit that occurs along fault zones developed in metasedimentary rocks with significant alteration, and Li is also hosted in clay minerals in the Jinyinshan area in Xianning, southern Hubei Province, China. The study area has no granitic rock outcrops, but approximately 15 km south is the Mufushan granite batholith, where large-scale rare metal mineralization, such as Li, Be, Nb and Ta granitic pegmatites, developed in the internal and outer contact zones of the granite batholith. In this study, high-Li clay minerals, including chlorite, kaolinite and smectite, were identified. The enrichment of Li is closely related to hydrothermal activity along the F9 fault in the region. Hydrothermal apatite coexisting with Li-clay in the orebody along the fault zone yielded an in situ U–Pb age of 135.2 ± 13.9 Ma, which is in good agreement with the ages of granites and Li-pegmatites around the Mufushan batholith. Petrographic, geochemical, and chronological evidence suggests that the ore-forming fluids and Li were likely sourced from the Mufushan granite batholith or a similar blind granite at the depth of the study area; that is, the granite-derived ore-forming fluids can travel long distances along fault zones, and during this pathway, Li from the metasedimentary rocks (i.e., the Lengjiaxi Group) may also have been leached by the fluids and contributed to the Li mineralization in the Jinyinshan clay-Li deposit. The close spatial relationships among different clay minerals indicate that fluid physical–chemical conditions (changes in temperature) may play a crucial role in controlling the formation of Li-rich clay minerals. Our study indicates that the Mufushan area has great potential for hydrothermal clay-Li mineralization occurring in the Lengjiaxi Group metasedimentary rocks around the Mufushan batholith. [ABSTRACT FROM AUTHOR]

The Wangjiadashan Cu–Au deposit is a vein‐type deposit controlled by the secondary faults of the Wushan Fault zone in the Suizao area of Hubei Province. Three hydrothermal stages are identified, namely, (I) barren quartz stage, (II) the quartz‐sulphide stage, and (III) quartz‐carbonate stage. Six types of fluid inclusions occur in quartz: (a) liquid‐rich aqueous fluid inclusions (L + V), (b) vapour‐rich aqueous‐carbonic fluid inclusions (V + L), (c) water‐rich aqueous‐carbonic fluid inclusions (L + V + CO2), (d) CO2‐rich aqueous‐carbonic fluid inclusions (V + L + CO2), (e) pure carbonic fluid inclusions (pure CO2), and (f) daughter mineral‐bearing multiphase inclusions (S‐type) with three subclasses (S1, S2, and S3 subtype). Two types of fluid inclusions occur in calcite: (a) liquid‐rich aqueous fluid inclusions (L + V) and (b) pure carbonic fluid inclusions (pure CO2). The S‐type fluid inclusions include halite (NaCl), calcite (CaCO3), and chalcopyrite (CuFeS2). The fluid system is composed of CO2–NaCl–H2O. The homogenization temperatures of the three stages are 295°C to 390°C, 245°C to 280°C, and 200°C to 241°C, with salinities of 7.3–19.8 wt% NaCl equiv. (except for several high values of 33.8 to 44.3 wt% NaCl equiv.), 7.7–13.7 wt% NaCl equiv., and 5.6–10.1 wt% NaCl equiv., respectively. Fluid immiscibility occurred in stage I that accounts for the high‐salinity fluids, but the dominant ore precipitation occurred afterward during temperature drop. In situ sulphur isotope analysis indicates a δ34S value around 0 (+1.1% to +2.2%) for the chalcopyrite, suggesting that the sulphur likely derived from the deep‐seated magma. Pyrites show δ34S values from −0.5‰ to +6.5‰ in stage II, from +0.7‰ to +6.6‰ in country rock of marble, but significantly higher from +12.8‰ to +21.7‰ in country rock of greenschist. These results indicate the sulphur for pyrite in stage II likely derived from the mixing of deep‐seated magma and country rocks. From stages I to II, a slightly increase of δD (from −86‰ and −73‰ to −59‰ and −56‰) and a decrease of δ18O (from 8.9‰ and 7.1‰ to 1.3‰ and 3.4‰) indicate that an increasing involvement of meteoric water. The carbon isotopes of fluid inclusions CO2 in quartz of stage I (−11.0‰ to −13.0‰) indicate a major magmatic or metamorphic carbon source mixed with minor sedimentary sourced carbon, but a major organic carbon source (−32.0‰ to −35.0‰) for stage II fluids. In conclusion, the Wangjiadashan Cu–Au deposit belongs to the orogenic type. [ABSTRACT FROM AUTHOR]

[Display omitted] • Calc-alkaline magma can exsolve high REE fluid. • High F content can facilitate the transportation of REE from magma into fluid. • The assimilation of evaporates enhances REE transportation. Hydrothermal fluids associated with carbonatites and peralkaline silicate rocks typically exhibit high REE content, but this is generally not the case for calc-alkaline rocks. However, the Tieshan skarn Fe-Cu deposit in the Edong district of Hubei Province in China demonstrates economic REE mineralization potential linked to calc-alkaline rocks. To investigate the presence of REE enrichment in the fluid, we present textural and compositional data of rock-forming mineral amphibole from the quartz diorite in the Tieshan deposit. Three distinct types of amphibole are identified in the Tieshan quartz diorite, namely Early amphibole , Main-stage amphibol e, and Late amphibole , following the crystallization sequence. Early amphibole (813–864 °C, 115–152 MPa) crystallized when the magma was emplaced at a depth of approximately 4.8 km. Main-stage amphibol e (741–806 °C, 58–103 MPa) crystallized at a depth of roughly 3 km. Between the early and main-stage amphibole crystallization, the magma experienced fractional crystallization of pyroxene, amphibole, and plagioclase, resulting in a REE enrichment in the residual melt. Late amphibole crystallized subsequent to the transition from lithostatic to hydrostatic stress states (656–729 °C, 27–52 MPa). Significantly, the transport of REE from the magma system initiated towards the end of Main-stage amphibol e crystallization. A comparison with the Tonglvshan granitic rocks in the same district indicates an elevated F content and extended fractional crystallization history in the Tieshan magma, contributing to REE enrichment in its melt. Furthermore, the high F content lowered the solidus temperature of the Tieshan magma, thereby facilitating the more efficient removal of REE into the fluid. The assimilation of evaporate into the magma possibly led to heightened sulfur and chlorine levels in the fluid, enabling the transport of a significant amount of REE. [ABSTRACT FROM AUTHOR]

In the Tongshankou porphyry deposit (SE Hubei Province, South China), three types of K-feldspars are recognized: (I) the phenocryst type in the porphyry that crystalized during the magmatic stage, (II) the megacryst type and (III) the vein type in the altered porphyry and orebody that was produced by hydrothermal fluids. A detailed in-situ analysis of trace elements and Sr-Pb isotopes was carried out on K-feldspars in an attempt to unravel their formation processes and to trace the element sources during potassic alteration. The Type III K-feldspars show lower Sr contents and Sr-isotope ratios but higher Pb contents and Pb-isotope ratios than the Type I and II K-feldspars, possibly reflecting a contribution from the country carbonate rocks with less radiogenic Sr but more radiogenic Pb sources, and indicate that the ore-forming fluids and materials may have been partially derived from external sources such as the host sedimentary rocks during the early potassic alteration stage. [ABSTRACT FROM AUTHOR]

The Tonglvshan deposit is the largest Cu-Fe (Au) skarn deposit in the Edong district, which is located in the westernmost part of the Middle and Lower Yangtze River metallogenic belt, China. In this study, we performed a detailed in situ analysis of major and trace elements in amphiboles from the ore-related Tonglvshan quartz monzodiorite porphyry using electron microprobe (EMPA) analysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Two distinct populations of amphiboles, which can be distinguished by their aluminum content, are found in the quartz monzodiorite porphyry. The low-aluminum (Low-Al) amphiboles are subhedral or anhedral and formed at 46.3-73.5 MPa and 713-763 °C. In contrast, the high-aluminum (High-Al) amphiboles are euhedral and formed at 88-165 MPa and 778-854 °C. Some euhedral amphiboles are partially or completely replaced by Low-Al amphibole. The compositions of parental melts in equilibrium with the High-Al amphibole ( Melt 1) and Low-Al amphibole ( Melt 2) were computed by applying solid/liquid partition coefficients. This modeling shows that magma in equilibrium with High-Al amphibole ( Melt 1) underwent 40% fractional crystallization of amphibole, plagioclase and apatite at a depth of ~5 km to evolve to magma in equilibrium with Low-Al amphibole ( Melt 2). Copper enrichment occurred in the magma after undergoing fractional crystallization. The magma had a high oxygen fugacity, increasing from NNO + 1 ( Melt 1) through NNO + 2 to HM ( Melt 2), which could have prevented the loss of Cu (and possibly Au) to sulfide minerals during crystallization. Finally, the evolved magma intruded to shallower depths, where it presumably exsolved aqueous ore-forming fluids. Therefore, the large Cu-Fe-Au reserves of the Tonglvshan deposit can likely be attributed to a combination of controlling factors, including high oxygen fugacity, fractional crystallization, fluid exsolution, and a shallow emplacement depth. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Suixian Mo deposit is a magmatic hydrothermal vein-type deposit related to intrusions. • The ore-forming fluid shows moderate-high temperature and rich in CO 2 and CH 4. • The ore materials derived from the mixture of magma and surrounding metamorphic rocks. • Mixed organic water and fluid immiscibility are two important ore-forming mechanisms. The Suixian Mo deposit is a recently discovered deposit in the northern Hubei Province, Tongbai orogen. The Mo orebodies of this deposit are all hosted in the metamorphic rocks (leuco-gneiss, amphibolite and marble) of the Neoproterozoic Tianwangzhai Group, and these orebodies have no direct contact with the granite surrounding the host rocks. The mineralization types are dominated by disseminated ore and fine Mo-bearing quartz-sulfide veins. Hydrothermal alteration consists of abundant feldspathization, epidotization and chloritization, together with less garnetization, tremolitization, and muscovitization. A detailed study on fluid inclusions and multiple isotope (C H O S Pb) analyses, together with geologic features, are carried out to investigate the fluid composition, fluid origin and evolution, the source of ore-forming materials, and the ore genetic type. In line with microthermometric measurements and laser Raman analysis on fluid inclusions from three hydrothermal stages, the ore-forming fluid in this deposit is characterized by medium–high temperatures and salinities, as well as richness in CO 2 and CH 4. Three hydrothermal stages are identified in this deposit, including (I) feldspar-quartz-amphibole-muscovite stage, (II) quartz-sulfides stage, and (III) quartz-calcite-scheelite-fluorite stage. From stages I, II to III, the temperatures change from 290 to 354 °C, through 229–312 °C, to 173–269 °C, with decreasing salinities of 12.6 to 16.3 wt% NaCl equiv., 4.5 to 13.4 wt% NaCl equiv., and 0.2 to 6.9 wt% NaCl equiv., respectively. Most of sulfur isotope data of sulfides (chalcopyrite, pyrite, pyrrhotite and molybdenite) show a narrow δ34S range from −2.0 to 3.0 ‰, suggesting a dominant magmatic source, but some data show either positive or negative values (δ34S: −13.3 to −10.6 ‰ and 9.8 to 11.2 ‰) which may indicate small contribution from the restricted wall rocks. The Pb isotope data (molybdenite, pyrite and pyrrhotite: 206Pb/204Pb: 17.239 to 18.483; 207Pb/204Pb: 15.378 to 15.717; 208Pb/204Pb: 37.889 to 38.850) imply that the lead of sulfides pertains to a mixture of magma (derived from the lower crust) and upper crustal materials (host metamorphic rocks). Based on evident CO 2 and CH 4 in fluid inclusions, the gradually depleted carbon isotopic compositions (δ13C: −5.4 to −9.9 ‰ at stage I, −14.8 to −19.7 ‰ at stage II, and −17.0 to −24.2 ‰ at stage III) and the H O isotope data, it is suggested that the ore-forming fluids were mainly magmatic fluids with mixture of some organic-containing water, and the thermochemical reaction between the fluids and organic matters (e.g., CH 4) from host metamorphic rocks and fluid immiscibility are two important mechanisms for Mo mineralization. Compared with typical Mo deposits in the same orogen, the Suixian Mo deposit belongs to the magmatic hydrothermal vein-type deposit associated with intrusions rather than porphyry or skarn type deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Heilongtan-Xiejiagou Au deposit is a magmatic-hydrothermal vein type deposit. • Ore-forming fluid is medium–low temperature and low salinity and with abundant CO 2. • Ore-forming fluid were derived from magmatic fluid with meteoric water mixture. • Ore-forming materials came from both deep-seated magma and surrounding strata. The Heilongtan-Xiejiagou Au deposit at Suizao (Suizhou-Zaoyang) area of Hubei province was recognized previously as an orogenic gold deposit by many researchers, in consistent with the fact that this area is dominated by extensive Early Cretaceous magmatism and associated magmatic hydrothermal deposits. In this study, we try to constrain the ore genetic type and formation mechanism of the Heilongtan-Xiejiagou Au deposit by studying the source of ore-forming fluids and materials. Three paragenetic mineralization stages were recognized, including (I) feldspar-quartz-sericite-pyrite veins, (II) quartz-sulfides veins, and (III) quartz-sulfides-carbonate veins. Combined Laser Raman analysis and microthermometry for fluid inclusions hosted in quartz and calcite, the fluid system of three hydrothermal stages is all composed of H 2 O-NaCl ± CO 2 with medium–low temperatures and salinities. A gradually decreasing trend has been recorded for temperatures from 224 to 339 °C, through 182–301 °C and towards 138–249 °C, respectively, together with salinities changing from 9.9 to 15.6 wt% NaCl eq., through 6.3–12.7 wt% NaCl eq., to 2.9–8.1 wt% NaCl eq. from early to late stages. The calculated fluid pressures range from 52 to 185 MPa at stage I, and the stages II and III vary from 42 to 128 MPa and 19 to 96 MPa, respectively. The in-situ sulfur isotope data suggest that the sulfur sources were dominantly mixture of magma and surrounding metamorphic rocks, and the C–H-O isotope data imply the mineralizing fluids were originated dominantly from magmatic fluid and mixed with some meteoric water. By means of comparison with regional magmatism and mineralization ages, we consider that the fluids may have originated from the buried granite that also supplied some sulfur and particularly heat energy to drive the fluid circulation system to extract metallogenic materials (Au and other elements) also from country rocks, resulting in mineralization after fluid flow into the fractures and faults of the metamorphic rock strata. In consequence, we draw a conclusion that the Heilongtan-Xiejiagou Au deposit pertains to hydrothermal quartz vein-type deposit controlled by both of magmatic fluid and structure. [ABSTRACT FROM AUTHOR]

Abstract: The Middle–Lower Yangtze River metallogenic belt (MLYRMB), extending from Daye in Hubei Province in the west to Zhenjiang in Jiangsu Province in the east, hosts a number of large polymetallic (Cu–Au–Mo, Fe, Zn, Pb, and Ag) deposits and constitutes one of the most important metallogenic belts in China. The Cu–Au–Mo deposits in the Jiurui district are an important component of the MLYRMB. In this study we carried out precise and detailed zircon U–Pb dating for all types of magmatic rocks from the Wushan ore deposit in the Jiurui district. Three samples of Cu–Au–Mo-related porphyries from different ore belts at Wushan were analyzed and yielded zircon U–Pb ages of 148.0±1.0Ma, 145.4±0.9Ma and 147.3±0.9Ma, respectively. A series of dykes were emplaced immediately following the Cu–Au–Mo-related porphyries at Wushan. A dark-colored basic dyke which intruded into the granodiorite porphyry at Wujia gold deposit near Wushan was dated at 144.5±1.2Ma. Two lamprophyre dykes taken from the north ore belt at Wushan underground mining stops were dated at 143.6±0.9Ma and 144.3±0.9Ma, respectively. A late-stage dyke which was also taken from the Wushan north ore belt yielded an age of 142.6±1.0Ma and might represent the end of magmatism in the Wushan ore deposit. These new geochronological data demonstrate that the time range of magmatism in the Wushan ore deposit is approximately between 148Ma and 143Ma, showing that the magmatic activity at Wushan was rapid and intensive. The ages of Cu–Au–Mo-related porphyries from other areas in the Jiurui district, such as the Dongleiwan, Yangjishan and Chengmenba ore deposits, were also measured and yielded zircon U–Pb ages of 141.5±1.7Ma, 143.4±1.4Ma and 146.6±1.0Ma, respectively. Combined with those previously reported zircon U–Pb age results from the Jiurui district, the present age data set demonstrates that extensive magmatism in the Jiurui district was coeval and intensive, marked by a magmatic activity in the age range of 148 to 138Ma and peaked between 148Ma and 142Ma. According to the statistics of all those precise zircon U–Pb ages, the Cu–Au–Mo-related porphyries in the Edong and Tongling districts in the MLYRMB show similar ages, and they have a slightly younger peak age and a longer duration than that of the Jiurui district. The geographic shape of the MLYRMB in the Cretaceous shows an arcuate structure, the Jiurui district is located at the transitional point of the arcuate structure and the Edong and Tongling districts are situated on both sides of the arcuate structure. Considering that the Jiurui district has a slightly older peak age and a shorter duration of magmatic activity than that in the Edong and Tongling districts, it seems that the arcuate structure of the MLYRMB played an important role in the formation of these Cu–Au–Mo-related porphyries. Consequently, we suggest that the genesis of the Late Mesozoic magmatic rocks along the MLYRMB may have been due to a tectonic activity developed from southeast to northwest, which probably has a close relationship with the subduction of the paleo-Pacific plate beneath the Eurasian plate in Mesozoic times. [Copyright &y& Elsevier]

[Display omitted] • Fractional crystallization elevates Cl content in magma. • Fluid exsolution depletes Cl content in magma. • Chlorine behaves different from sulfur in magmatic rocks. • In-situ study is necessary when using apatite as a volatile tracer. In order to trace chlorine and sulfur evolution during magma evolution, detailed petrographic observation, major- and trace-element analysis of amphibole and apatite were carried out on the ore-related pluton in the Tonglvshan Cu-Fe (Au) skarn deposit, Hubei Province, South China. Several generations of apatite and amphibole are identified, from early to late including: (1) apatite in euhedral amphibole; (2) euhedral amphibole; (3) apatite in subhedral-anhedral amphibole/plagioclase; (4) subhedral-anhedral amphibole + plagioclase; (5) apatite in K-feldspar or quartz; and (6) K-feldspar + quartz. Most apatites show homogeneous textures, but a few apatite grains enclosed in amphibole and plagioclase (1 and 3) display oscillatory zoning. These zoned apatites crystallized in semi-closed environments created as growth of amphibole or plagioclase removed components of the melt. The magmatic Cl and S evolution can be divided into three stages: (I) In the deep magma chamber, at ∼ 5 km below the surface, magma underwent ∼ 39% fractional crystallization, and its Cl and S contents increased simultaneously; (II) In a shallow magma chamber at ∼ 2.5 km depth, fractional crystallization elevates Cl and S contents in the residual melt, but fluid exsolution depletes them; (III) At near-solidus stage, when fluid exsolution becomes weak, crystallization elevates Cl and S contents in the residual melt simultaneously. This study suggests that the silicate mineral (fractional) crystallization can elevate Cl content in residual melt, and fluid exsolution can efficiently remove Cl from the magma. Bulk sulfur in magma may be transported not only as dissolved sulfur, but also as sulfates like anhydrite. The sulfur content of apatite is controlled by the sulfur composition in melt from which the apatite crystallizes, but Cl in apatite may represent re-equilibration between the apatite and the last melt in contact with the apatite, because of rapid diffusion of Cl in apatite. These characteristics along with complex apatite generations imply that in-situ study is necessary when using apatite to trace volatile composition in magma. [ABSTRACT FROM AUTHOR]

The Tongbai orogen is located in the northern Hubei and southern Henan provinces, together with the Qinling, Hong'an and Dabie orogens they constitute one of the most important orogenic belt separated the North China Block and Yangtze Block. Among these orogens, the Tongbai receives less attention and its magmatic and tectonic evolution is still unclear. In this paper, we present a detailed study on geochronology, geochemistry and Sr-Nd-Pb-Hf isotopes of the five plutons (Daxianduo, Jinziling, Sanguanduo, Sanhedian and Zhoulou) that composes the Qijianfeng Granite Complex in Suizao area, in order to better understanding the Late Mesozoic magmatic and tectonic evolution of the Tongbai orogen. The LA-ICP-MS U Pb dating of zircon suggests an Early Cretaceous emplacement age (135–139 Ma) for the Qijianfeng Granite Complex. All the five plutons of the Qijianfeng Granite Complex are weakly peraluminous and belong to high-K calc-alkaline series and post-collisional I type granites. The chemical and isotopic compositions of the Qijianfeng Granite Complex show SiO 2 contents of 69.84–74.36 wt%, Al 2 O 3 of 13.85–15.62 wt%, MgO of 0.16–0.52 wt%, N 2 O/K 2 O of 0.99–1.73; 506–1205 ppm Sr, 3.4–12.9 ppm Y, 0.49–1.25 ppm Yb; Eu/Eu* values of 0.7–1.0, LREE/HREE values of 3.1–9.5; 87Sr/86Sr values of 0.7057–0.7080 and ε Nd(t) values of −16.59 to −6.18, which share similarities with the C-type (high-K) adakite. The low MgO, Ni and Cr contents further suggest that the Qijianfeng Granite Complex belongs to adakite derived from partial melting of thickened lower continental crust. Combined with the geochemical characteristics of other contemporaneous intrusions in the whole orogen, our study shows that the extensive Early Cretaceous adakitic magmatic activity is triggered by lower crustal thickened, mountain-basin coupling and crust-mantle interaction in the Tongbai orogeny. • The Qijianfeng complex was formed at 135–139 Ma. • The Qijianfeng complex is a typical adakitic I-type granite. • The granites formed mainly by partial melting of a thickened lower continental crust. • Crust-mantle magma mixing contributes to the granite petrogenesis. • The mountain-basin coupling plays a role in the granite petrogenesis. [ABSTRACT FROM AUTHOR]

• The Zaopa Ag-Mo prospect is a structurally-controlled hydrothermal vein type deposit. • The composition of the ore-forming fluid system is CO 2 -NaCl-H 2 O. • The temperatures and salinities decrease from early to late stage. • The ore-forming fluid was derived from a magmatic source. • Meteoric water and organic carbon involved in the ore system. The Zaopa Ag-Mo prospect is located in the Tongbai-Dabie orogenic belt in central China. The orebodies occur as quartz veins and are controlled by secondary faults of the Wushan fault zone in the Suizao area, and hosted by the Zhoulou granite. We document three hydrothermal stages, characterized by albite-quartz-sulfide veins (stage I), quartz-sulfide (stage II) and quartz-fluorite assemblages (stage III), respectively. Silver is mainly found in hessite and galena. There are three types of fluid inclusions in quartz and fluorite including: (1) liquid-rich aqueous fluid inclusions (L + V); (2) aqueous-carbonic fluid inclusions (L + V + CO 2); (3) pure carbonic fluid inclusions (pure CO 2). Laser Raman spectroscopic analyses indicate the existence of carbon dioxide in the fluid inclusions. The fluid system of the Zaopa Ag-Mo prospect is composed of CO 2 -NaCl-H 2 O. The homogenization temperatures of the three stages are 380 to 495 °C, 337 to 404 °C and 246 to 336 °C, respectively. The salinities of the three stages are 11.1–17.5 wt% NaCl eq., 6.7–12.7 wt% NaCl eq. and 1.6–9.9 wt% NaCl eq., respectively. The stage I sulfides (molybdenite, chalcopyrite, pyrite) show a δ34S value around 0‰ (−3.1 to +1.0‰), indicating a magmatic origin. The stage II sulfides (galena, sphalerite, pyrite) also show a δ34S value around 0‰ (−5.7 to +1.6‰), again indicating a magmatic origin. The C-H-O isotope data shows that the fluids of the early stage were derived from a magmatic source, but the fluids of the late stage mixed with meteoric waters. By comparing the characteristics of the Mo deposits in China and those from other countries, we conclude that the Zaopa Ag-Mo prospect is a structurally-controlled magmatic-hydrothermal vein type deposit. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Fujiashan-Longjiaoshan deposit is an oxided Cu-W-(Mo) skarn deposit. • The pristine ore-forming fluids and materials originated from magmatic rocks. • The fluid is high-T, high-salinity and high- f O 2 NaCl-KCl-H 2 O system. • Meteoric water and organic matter are involved in the quartz-sulfide stage. • Cooling, meteoric water mixing, fluid boiling produced scheelite precipitation. Abstract The Fujiashan-Longjiaoshan deposit is located in the southern area of the Edong District of the Middle-Lower Yangtze River metallogenic belt. W-Cu-(Mo) orebodies are found in the contact zone between the granodiorite porphyry and Carboniferous to Triassic carbonate strata. Four stages of ore formation are identified: (1) the prograde skarn stage, (2) retrograde skarn stage, (3) quartz-sulfide stage (further subdivided into the early 3a and later 3b), and (4) carbonate stage. In this study, we applied fluid inclusion microthermometry, laser Raman spectroscopy, and H-O-C-S-Pb isotopic compositions to constrain hydrothermal processes and ore precipitation mechanisms of the Fujiashan-Longjiaoshan deposit. Early stage (1 and 2) ore-forming fluids belong to a high-temperature (above 550 °C), high-salinity (60–70 wt% NaCl equiv. and 15–20 wt% NaCl equiv, respectively), high-pressure (above 700 bars) and high-oxygen-fugacity NaCl-KCl-H 2 O system, and in the quartz-sulfide stage 3, the system changes into a NaCl-KCl-CO 2 -H 2 O system. Homogenization temperatures and salinities of ore-forming fluids gradually decrease throughout the evolutionary process. Fluid temperatures vary at >550 °C in prograde skarn stage 1, from 350 to 400 °C in retrograde skarn stage 2, from 250 to 300 °C in quartz-sulfide stage 3, and finally from 100 to 150 °C in carbonate stage 4. Salinity levels vary from 15 to 20 wt% NaCl equiv. in prograde skarn stage 1, from 5 to 20 wt% NaCl equiv. in retrograde skarn stage 2, from 10 to 15 wt% NaCl equiv. in quartz-sulfide stage 3a, from 5 to 10 wt% NaCl equiv. in quartz-sulfide stage 3b, and from 0 to 5 wt% NaCl equiv. in carbonate stage 4. The H-O-C isotopic compositions indicate that the ore-forming fluids were derived from magmatic water (δD of −123‰ to −83‰, δ18O V-SMOW of 6.1‰ to 7.4‰) with the input of meteoric water and organic matter in the quartz-sulfide stage (δD of −91‰ to −53‰, δ18O V-SMOW of 2.4‰ to 4.6‰, and δC V-PDB of −14.7‰ to −6.4‰). Sulfur and Pb isotopic compositions show that the ore-forming materials were mainly derived from granitic magma (δ34S V-CDT values of granodiorite-porphyry sulfides and skarns of −5.7‰ to +6.6‰) and in part from host sedimentary strata (δ34S V-CDT values of sulfides of country rocks clustering at −20‰ and at −10‰). Fluid boiling in the retrograde skarn stage gave rise to the first precipitation of scheelite. The precipitation of scheelite, chalcopyrite and molybdenite in the quartz-sulfide stage was probably triggered by the input of meteoric water and organic carbon. According to mineral assemblages and all available geological and geochemical data, we conclude that the Fujiashan-Longjiaoshan deposit is an oxidized skarn-type W-Cu-(Mo) deposit. [ABSTRACT FROM AUTHOR]

The Baiguoyuan Ag-V ore deposit in Xingshan County, Hubei Province, is hosted in Neoproterozoic black shale, containing approximately 1860 tons Ag at average grade of 116 g/t and 21.8 Mt. V at average grade of 1.5%. The occurrence, source and enrichment mechanism of silver in this deposit are still a topic of debate. In this study, we applied high-resolution electron microprobe analysis (EMPA) and LA-ICP-MS technique to determine the occurrence of silver and to infer its source and enrichment mechanism. Mineralography observation revealed that pyrite is the main metallic mineral in the ores, which shows three-stage formation histories: (1) sedimentation, (2) diagenesis, and (3) deformation. BSE imaging detected tiny naumannite inclusions in pyrite. EMPA showed high contents of Ag in sedimentary pyrite. LA-ICP-MS analysis displayed both solid solution and tiny naumannite inclusion of Ag in pyrite. A mass balance calculation suggested that Ag occurred mainly as solid solution and minor as tiny naumannite inclusions in pyrite. The high contents of Co and Se, and high ratios of Co/Ni and Se/S in sedimentary pyrite indicated that Ag was probably supplied by submarine hydrothermal venting. The correlation between Ag and Fe or Se in sedimentary pyrite indicated that Ag was enriched through Ag and Se replacing Fe and S in pyrite, respectively. [ABSTRACT FROM AUTHOR]