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The study of the fluid inclusions of W–Mo deposits in the mineralization area of Ningshan–Zhen'an , Shaanxi Province, China shows that the gas–liquid two-phase inclusions are mainly present in W–Mo deposits, and the ore-forming fluid can be divided into four types: high-temperature type, middle–high-temperature type, middle-temperature type and low-temperature type. The formation depths of the W–Mo mineralization range from 4.2 to 8.4 km. The boiling and mixing of fluid may have been important mechanisms for the formation of W–Mo mineralization. The skarn-type mineralization is dominated by magmatic water, the quartz-vein-type mineralization includes both magmatic water and meteoric water, and the meteoric water is more involved in the quartz-fluorite-vein-type, beryl-quartz-vein-type and pegmatite-type mineralization. Magma is the main source of sulfur; that is, magma is the main source of mineralization. Combined with the metallogenic setting and geological characteristics of typical ore deposits, in the process of structural system transformation in South Qinling, the ore-forming magma fluid in the Late Indosinian–Yanshanian period was uplifted and emplaced along the NW–WNW direction and NE–NNE direction, and eventually, NW–WNW fault-controlled skarn-type W–Mo mineralization and quartz-vein-type W–Mo deposits accompanied by greisenization, albitization and potash feldspathization formed. [ABSTRACT FROM AUTHOR]

The Shimensi super-large tungsten polymetallic deposit is located in the Late Jurassic–Early Cretaceous Porphyry–Skarn tungsten ore belt in the south Yangtze metallogenic belt. There are three types of mineralization: veinlet-disseminated type, thick quartz vein type and hydrothermal cryptoexplosive breccia type. Based on geological studies, this paper presents new petrographic, microthermometric, laser Raman spectroscopic and hydrogen and oxygen isotope research on the fluid inclusions from the deposit. The results show that there are five different types of fluid inclusions: liquid-rich inclusions, vapor-rich inclusions, pure liquid inclusions, pure vapor inclusions, and fluid inclusions containing a solid crystal. The homogenization temperatures of the fluid inclusion range from 140 °C to 270 °C, the salinities are 3 wt.%–5 wt.% NaCleq and the densities of ore-forming fluid range from 0.64 g/cm3 to 0.99 g/cm3. For the analyses of laser Raman spectroscopy, the ore-forming fluids can be approximated by a Ca2+-Na+-SO42−-Cl− fluid system with small amounts of CO2, CH4 and N2. Otherwise, the data of the pressure, pH and Eh show a fluid metallogenic environment of low pressure, weak acid and weak reduction. The values of the homogenization temperature in the three types of orebodies suggest that the mineralization is characterized by a decrease in temperature under the conditions of fluid immiscibility. The H-O isotope values are interpreted to indicate that the ore-forming fluids are mainly composed of magmatic water, and meteoric water is added with the process of magma rising. [ABSTRACT FROM AUTHOR]

The Yama area is characterized by numerous large-scale fluorite–quartz veins that are located along faults within the widespread Late Devonian–Late Silurian syenogranites in the Tataleng granitic batholith, Qilian Orogen, Northwest China. These fluorite–quartz veins contribute to an important fluorite reserve, but their ore genesis remains unresolved so far. In this study, trace elements, rare earth elements (REEs), and hydrogen, oxygen, and strontium isotopic compositions of fluorites are analyzed. The studied fluorite samples have similar chondrite-normalized REEs, including Y patterns, with relatively strong enrichment in heavy REEs, negative Eu anomalies, strongly positive Y anomalies, and comparably invariable Y/Ho ratios of 41.43–73.79, suggesting a unique hydrothermal genesis. The relatively variable values of δD and δ18O are −77.4‰ to −102.4‰ and −12.7‰ to −4.3‰, respectively, close to the meteoric water line. These fluorites yield relatively invariable analytical 87Sr/86Sr ratios of 0.749089−0.756628 (except for an anomalously high ratio), and their calculated initial 87Sr/86Sr ratios, based on the ore-forming ages provided, are apparently higher than the calculated initial 87Sr/86Sr ratios of syenogranite wall rocks. Collectively, the geochemistry of trace elements, REEs, and stable isotopes (H, O, and Sr) suggests that the ore-forming fluids were of meteoric origin and that the Sr sources were directly derived from the ore-forming fluids themselves rather than syenogranite wall rocks. Finally, it was considered that the Yama fluorite deposit is a fault-controlled hydrothermal vein-type deposit which was possibly related to the evolution of the Paleo-Tethys Ocean in the Permian–Triassic. [ABSTRACT FROM AUTHOR]

The Laoyingqing zinc deposit is located in the Pb-Zn deposit concentration district in northeastern Yunnan, with a geotectonic location on the southwestern edge of the Yangtze block. This deposit occurs in the interlayer fracture zone of the Huangcaoling Formation slate in the Middle Proterozoic Kunyang Group. In this deposit, zinc is significantly enriched compared to lead, and the sulfur isotopic composition of sphalerite shows δ34SCDT close to negative values. These characteristics are different from the common Pb-Zn deposits that occur in Sinian and Carboniferous carbonate rocks in northeastern Yunnan. The genesis of this deposit and its similarities to and differences from other Pb-Zn deposits hosted in carbonate rocks in the Sichuan–Yunnan–Guizhou Pb-Zn metallogenic triangle area (SYGT) need further research. This article selects typical rock (ore) samples for fluid inclusion, trace element, and H–O isotope analyses. The results show that (1) the homogenization temperature of the fluid inclusions is 130~306.5 °C, the salinity is 7.17 wt%~20.67 wt% NaCleq, and the density of the ore-forming fluids is 0.86–1.07 g/cm3. Overall, these ore-forming fluids belong to medium–low-temperature, medium–low-salinity, and medium–low-density ore-forming fluids, and they have reducibility. The fluid pressure is 36.3~85.6 Mpa, and the mineralization depth is 1.34~3.17 km. (2) The ore-forming fluids mainly came from deep-source metamorphic water and basin brine containing organic matter. (3) The ore-forming materials mainly came from the surrounding rocks (Kunyang Group). (4) The trace element characteristics of this deposit are different from sedimentary-exhalative type, magmatic hydrothermal type, and skarn type of Pb-Zn deposits, and have little difference from MVT Pb-Zn deposits. Based on the comprehensive analysis, this deposit is classified as a medium–low-temperature hydrothermal vein-type zinc deposit unrelated to magmatic activity. This study extends the ore-bearing surrounding rocks of Pb-Zn deposits in the SYGT to the slate of the Kunyang Group, enriching the regional Pb-Zn deposit mineralization theory and providing new ideas for mineralization prediction. [ABSTRACT FROM AUTHOR]

This paper studies the mineralization process and the ore-forming setting of the Kantian fluorite deposit in South China through the zircon U-Pb chronology, quartz Rb-Sr dating, whole rock geochemistry, H-O isotope and fluid inclusions. A mineralization model for the Kantian fluorite deposit is proposed as follows: The subduction of the Pacific plate during the late mid-Jurassic and late Jurassic led to the formation of several fault zones. As the subduction gradually decelerated and eventually ceased, continental extension and lithosphere thinning occurred, accompanied by upwelling of the asthenosphere. This asthenosphere upwelling facilitated melting of the lithospheric mantle, resulting in the ascent of magma into the lower crust. Consequently, the intrusion of magma into the lower crust caused substantial heat, triggering partial melting of the lower crust. The molten material then ascended along faults, generating a significant quantity of granites. During the Early Cretaceous period, the Yanshan cycle witnessed another notable phase of magmatic activity. The residual magmatic hydrothermal fluid from this period served as a source of heating, while the pre-existing fault structures provided favorable pathways and storage space. Atmospheric precipitation infiltrated into the depth along these faults, and the deep-seated residual magmatic hydrothermal fluid heated the infiltrated atmospheric water, inducing cyclic upwelling. The upward migration of hydrothermal fluid continuously extracted Ca and F elements from the granites. Ongoing interaction between the fluid and the surrounding rocks led to changes in pH, coupled with alterations in temperature and pressure, ultimately resulting in the precipitation of fluorite with associated alteration zones in the surrounding rocks. [Display omitted] • Ca and F element in the fluorite were derived through the surrounding rocks. • The ore-forming fluids belong to the NaCl-H 2 O system and exhibit characteristics of medium–low temperature, low salinity, and low density, and were derived from meteoric water. • The intrusion age of surrounding rock in Kantian fluorite deposit was 159.4 ± 2.2 Ma, and the ore-forming of fluorite was 135.6 ± 0.7 Ma. • The tectonic setting responsible for the diagenesis and mineralization processes is believed to be an intracontinental stretching environment associated with the subduction of the Pacific plate. The Yanshanian events have led to the development of South China as a unique granite province globally. Within South Jiangxi, numerous metallic and non-metallic deposits have a close association with Mesozoic granite formations. The Kantian fluorite deposit, a newly discovered non-metallic deposit in southern Jiangxi Province, is one such deposit that is linked to Mesozoic granites. The orebody at the Kantian fluorite deposit is identified as occurring in veined structures within the silicification fracture zone of Mesozoic granites, with strict control exerted by fault systems. Fluorite ore can be classified into two categories based on the amount of quartz and fluorite. The first category is the fluorite quartz type, which has a higher amount of quartz than fluorite. The second category is quartz fluorite type, which has more fluorite than quartz. Among these two categories, the quartz fluorite type is precipitated during the primary mineralization stage. Through the analysis of fluid inclusions within the fluorite, it was determined that the homogenization temperature is relatively low, ranging from 133 to 236℃. The fluid inclusions also display low salinity (0.18–3.39 wt% NaCl eqv.) and low density (0.75–0.96 g/cm3). Laser Raman spectroscopy revealed that the primary components of the fluid inclusions are H 2 O, with minor C 3 H 6. Isotope analysis indicated δD VSMOW values of fluorite ranging from −61.9 ‰ to −54.8 ‰ (average −59.8 ‰), while δ18O VSMOW values varied from 1.3 ‰ to 3.1 ‰ (average 2.0 ‰). This study presents chronological, petrological and geochemical data that suggest several processes. The metallogenic age is 135.6 ± 0.7 Ma. The mineralizing fluids were identified to the NaCl-H 2 O system, with heated meteoric water identified as the primary source; The ore-forming materials originated from the granite, and water–rock interactions are proposed as the primary mechanism for fluorite precipitation. Based on a tectonic setting characterized by stretching, which is closely linked to the subduction of the Pacific plate, we proposed a model for the Kantian fluorite deposit. [ABSTRACT FROM AUTHOR]

The Chayong Cu-polymetallic deposit is a recently discovered Cu-polymetallic deposit hosted in the Sanjiang Metallogenic Belt within the Tibetan Plateau of China to the northeast of the North Qiangtang terrane. The ore body occurs in siltstone and is controlled by a northwest-trending fault structure. According to the associations, assemblages, and cutting relationships between ore veins, the hydrothermal mineralization period can be divided into three mineralization stages: (1) a molybdenite mineralization stage, (2) a Cu-polymetallic sulfide stage, and (3) a quartz-carbonate stage. Two types of fluid inclusions (FIs), namely, liquid and vapor-rich inclusions, are present in quartz associated with sulfide minerals. Early-stage FIs are both liquid and vapor-rich, homogenized at temperatures ranging from 364.1 to 384.2 °C, and have salinities ranging from 0.70% to 9.60% NaCl equivalent (eqv). The middle-stage FIs are also both liquid- and vapor-rich, homogenized at temperatures ranging from 272.4 to 355.6 °C, and have salinities ranging from 0.53%–17.10% NaCl eqv. The late-stage FIs are liquid, homogenized at temperatures ranging from 209.4 to 255.3 °C, and have salinities ranging from 0.35%–6.87% NaCl eqv. The samples from the deposit have δ34S values of − 21.8‰ to − 19.2‰ and − 5.5‰ to − 6.0‰, suggesting that sulfur was derived from the host sediments and magmatic fluids, respectively. The metallic minerals within the deposit have 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of 18.439–18.458, 15.656–15.679, and 38.772–38.863, respectively, suggesting that the metals were derived from the upper crust and orogenic belts. The samples from the deposit have δ18OW values of 2.99‰–7.99‰ and δDW values ranging from − 84.4‰ to − 73.9‰, indicating that the ore-forming fluids were magmatic and mixed with minor amounts of meteoric water. The ore-forming fluid of the Chayong copper polymetallic deposit was a high-temperature, medium- to low-salinity H2O–NaCl–CH4–N2 ± CO2 fluid system. The early high-temperature magmatic fluid, due to boiling, decreased in temperature, and via the mixing of meteoric water, gradually evolved towards the later-stage medium- to low-temperature and low-salinity fluid, causing molybdenite mineralization and forming copper polymetallic sulfide veins and quartz carbonate veins. [ABSTRACT FROM AUTHOR]

Linghu gold deposit is located at Xiaoqinling area in the southern margin of North China Craton. Ore bodies occur as veins in the fault zones. The ore-forming process can be divided into three stages, including quartz-pyrite stage, quartz-polymetallic sulfide stage and quartz-carbonate-pyrite stage. Quartz-polymetallic sulfide stage is the main mineralization stage, and gold mainly precipitates in this stage. Three types of fluid inclusions are distinguished in various quartz veins, including liquid-rich, gas-rich and H2O-CO2 inclusions. The fluid inclusions in the quartz of quartz-pyrite stage are liquid-rich; the homogenization temperatures, salinities, and densities are 424 oC ~ 499 oC, 11. 5% ~ 13. 6% NaCleq, and 0. 55 ~ 0. 66 g • cm-3, respectively. The fluid inclusions in the quartz of quartz-polymetallic sulfide stage consist of liquid-rich, gas-rich and H2O-CO2; the homogenization temperatures, salinities, and densities are 291 oC ~ 389 oC, 0. 4% ~ 11. 8% NaCleq, and 0. 50 ~ 0. 83 g • cm-3, respectively. There are liquid-rich and gas-rich inclusions in the quartz of quartz-carbonate-pyrite stage; the homogenization temperatures, salinities, and densities are 206 oC ~ 289 oC, 8. 3% ~ 22. 2% NaCleq, and 0. 83 ~ 0. 99 g • cm-3, respectively. The ore-forming fluids of Linghu gold deposit are generally characterized by high temperature, moderate-low salinity, and low density. The δ18 OH2O values calculated for ore-bearing quartz range from 0. 7‰ to 4. 5‰, and the δD values from bulk extraction of fluid inclusion water range from -106. 4‰ to - 86. 1‰, suggesting that the ore-forming fluid consists dominantly of magmatic water. The δ34 S values range from - 8. 5‰ to 2. 4‰, and the 206 Pb/ 204 Pb, 201 Pb/204 Pb, 208 Pb/204 Pb ratios of ore sulfides are in the ranges of 17. 202-17. 79 6, 15. 448- 15. 473, and 37. 712-38. 255, respectively. The analysis results of S-Pb isotope indicate that the ore-forming materials mainly come from the granitic magma formed from partial melting of the lower lower- crust. Linghu gold deposit is a magmatic-hyrothermal gold deposit; fluid phase separation and temperature decrease are the dominant mechanisms for the deposition of ore-forming materials. [ABSTRACT FROM AUTHOR]

We studied the fluid inclusions of the Jiguanshan Mo deposit in China, which is a large porphyry deposit located in the southern Xilamulun Metallogenic Belt. The irregular Mo ore body with various types of hydrothermal veinlets is hosted by Late Jurassic granite porphyry. Intense hydrothermal alterations in the deposit from the core to margin are silicification–potassium feldspar alteration, pyrite–quartz–sericite–fluorite alteration, and propylitic alteration. Based on the mineral assemblages and crosscutting relationships of ore veins, the ore-forming process were divided into three stages and two substages: quartz–pyrite veins (stage I) associated with potassic alteration; quartz–molybdenite–chalcopyrite–pyrite veins (substage II-1) and quartz–molybdenite–fluorite veins (substage II-2) associated with phyllic alteration; and fluorite–quartz–carbonate veins (stage III) with carbonation. Five major fluid inclusions (FIs) types were distinguished in the quartz associated with oxide and sulfide minerals, i.e. polyphase brine (Pb-type), opaque-bearing brine (Ob-type), solid halite (S-type), two-phase aqueous (A-type), and vapor (V-type) inclusions. The FIs of stage I were composed of liquid-rich S-, A-, and V-type FIs with homogenization temperatures and salinities of 490 to 511 °C and 8.9 to 56.0 wt% NaCl equiv., respectively. The FIs of substage II-1 are composed of Pb-, Ob-, S-, A-, and V-type FIs with homogenization temperatures and salinities of 352 to 460 °C and 3.7 to 46.1 wt% NaCl equiv, respectively. The FIs of substage II-2 are Ob-, S-, A-, and V-type FIs with homogenization temperatures and salinities of 234 to 309 °C and 3.7 to 39.2 wt% NaCl equiv, respectively. The FIs of stage III are A-type FIs with homogenization temperatures and salinities of 136 to 172 °C and 1.1 to 8.9 wt% NaCl equiv, respectively. Fluid boiling, which resulted in the precipitation of sulfides, occurred in stages I and II. The initial ore-forming fluids of the Jiguanshan deposit had high temperature, high salinity, and belonged to an F-rich NaCl ± KCl–H2O system. The fluids gradually evolved to low temperature, low salinity, and belonged to a NaCl–H2O system. Studies of the hydrogen and oxygen isotope compositions of quartz (δ18OH2O = − 7.3 to 6.3‰, δDH2O = − 104.3 to − 83.3‰) show that the ore-forming fluids gradually evolved from magmatic water to meteoric water. [ABSTRACT FROM AUTHOR]

The recently discovered Bulage Pb–Zn deposit is located in the central part of the Erlianhot–Dongwuqi Metallogenic Belt (eastern Central Asian Orogenic Belt) in Inner Mongolia, China. The ore bodies of the deposit are hosted in alkali feldspar granite and in dacitic crystal tuff within Unit 2 of the Carboniferous Baoligaomiao Formation. The Bulage deposit is a low to moderate temperature hydrothermal vein‐type deposit and is controlled by fractures. The hydrothermal mineralization can be divided into three stages: early (quartz + specularite ± magnetite), middle (quartz + sphalerite + galena ± chalcopyrite ± pyrite), and late (calcite ± quartz + sphalerite + galena). The deposit contains liquid‐rich two‐phase (VL‐type) and pure‐liquid (L‐type) fluid inclusions. The initial ore‐forming fluids are attributed to the low to moderate temperature and low salinity of a NaCl–H2O system. Hydrogen and oxygen isotopic compositions of quartz and calcite indicate that the ore‐forming fluids were dominated by meteoric water with minor contributions of magmatic water. The quartz diorite, monzonite porphyry, and alkali feldspar granite in the deposit yield LA–ICP–MS zircon U–Pb ages of 305–300 Ma. These high‐K calc‐alkaline I‐type granitoids are enriched in large‐ion lithophile elements (LILEs; e.g., Rb, Cs, and K) and light rare earth elements (LREEs) and are depleted in high‐field‐strength elements (HFSEs; e.g., Nb, Ta, and Ti) and heavy rare earth elements (HREEs). The primary magma of these granitoids was derived from the partial melting of lower crust. The parental magma of the quartz diorite may have provided part of the ore‐forming material and acted as a heat source for mineralization. Therefore, we infer that the Bulage Pb–Zn deposit was formed as a result of the southward subduction of the Paleo–Asian Ocean beneath the North China Craton during the Late Carboniferous. [ABSTRACT FROM AUTHOR]

The geochemical analysis of H-O-S-Pb isotopes in the Herenping Gold Mine was carried out. The δ34S values of sulfides from ore lie in-4.8‰~2.0‰. The ratios of 206Pb/204Pb， 207Pb/204Pb and 208Pb/204Pb from sulfide ores are 17.419~17.436， 15.519~15.535 and 37.86~37.90， respectively. The δD values of the fluid fall in-62.3‰~-53.0‰，and the δ18O values of the fluid are 4.2‰~11.8‰. These sulfur， lead， hydrogen and oxygen composition indicate that the ore-forming materials originate from the depth and the ore-forming fluid from magmatic hydrothermal， and mineralization has the characteristics of redox which formed the faded alteration zone in the region. Considering that the Herenping gold deposit is related to the deep magmatism， the ore prospecting should focus on the redox interface in the host strata and the faded alteration is the main indicator for the deposit. [ABSTRACT FROM AUTHOR]

The Qiman Tagh W-Sn ore belt is located in the westernmost sector of the East Kunlun Orogen, NW China. It has been recognized as a unique W-Sn belt that formed in the early Paleozoic and related to closure of the Proto-Tethys. To understand the evolution of ore-forming fluids and its relationship with the tectonic setting of East Kunlun Orogen, we report the results obtained from fluid inclusion and H-O isotopic studies of ores and quartz veins for the Qiman Tagh W-Sn ore belt. Mineralization in Qiman Tagh includes four stages characterized by quartz-cassiterite-wolframite assemblage stage 1, quartz ± scheelite assemblage stage 2, quartz-polymetallic sulfides stage 3, and ore-barren veins stage 4. The former two stages are conducive to mineralization, while the latter two stages are less important. The fluid inclusions are distinguished between CO 2 -H 2 O (C-type) and NaCl-H 2 O (W-type) in composition, containing a trace of CH 4 , N 2 , C 2 H 6 , SO 2 , and CO 3 2– . Cassiterite and quartz in stage 1, instead of wolframite, contain a great deal of C-type inclusions. All inclusions in minerals of stage 1 yield homogenization temperatures of 230.1–384.1 °C (peaking at 310–320 °C), with salinities lower than 14.76 wt% NaCl equiv. and bulk densities of 0.63–0.89 g/cm 3 . The stage 2 minerals contain both two types of inclusions, yielding homogenization temperatures of 183.4–335.9 °C (peaking at 280–290 °C), with salinities lower than 14.53 wt% NaCl equiv. and bulk densities of 0.66–0.97 g/cm 3 . Fluid inclusions in minerals of stages 3 and 4 are mainly W-type and homogenized at temperatures of 140.6–277.6 °C (peaking 210–220 °C), and 116.9–255.1 °C (peaking 160–170 °C), respectively. The H-O isotopic systematics shows that the fluids were dominated by magmatic water in stages 1 and 2, but by meteoric water in stages 3 and 4. Integrating all the geological and geochemical data, we conclude that the fluids forming the Qiman Tagh W-Sn ore belt evolved from granite-derived, CO 2 -rich and reducing, to meteoric water-dominated, CO 2 -poor and oxidizing. Fluid immiscibility, cooling and interaction with rocks are main mechanisms for metallic deposition. [ABSTRACT FROM AUTHOR]

The Daheishan giant porphyry Mo deposit is located at the eastern segment of the CAOB, NE China. The ore-bearing intrusion of Daheishan deposit is a Jurassic granitic complex that includes Changgangling biotite granodiorite, Qiancuoluo seriate granodiorite, and Qiancuoluo granodioritic porphyry. Mineralization consists of disseminated, breccia and veined types. The hydrothermal fluids show significant magmatic signatures, as evidenced by the hydrogen and oxygen isotopic compositions of quartz and sulfur isotopic characteristics of ores. Consistence of lead isotopic compositions of the sulfides and the Daheishan intrusive complex further indicate a close relationship between the mineralization and magma. The fluid inclusions in quartz comprise of predominant aqueous two-phase as well as gas-rich fluid inclusions and a small number of daughter mineral-bearing inclusions. The gas species in the fluid inclusions are H 2 O, CO 2 , N 2 , CH 4 , C 2 H 6 , Ar ∗ and minor H 2 S; the liquid compositions are SO 4 2 − , Cl − , Na + , K + , Ca 2+ and Mg 2+ . Raman spectroscopy on individual fluid inclusions reveals a main gaseous composition of H 2 O, minor H 2 S and CO 2 . The fluid system in Daheishan Mo deposit can be described as NaCl–KCl–H 2 O type. Fluid inclusion microthermometry reveals subsolidus homogenization temperatures for fluid inclusions in the magmatic quartz phenocrysts ( T h = 400–450 °C, salinities = ∼21 eq. wt.%), suggesting an obliteration of higher temperature history of the porphyry system by the superimposed processes. Most of the mineralization occurred at temperature range of 220–360 °C, or higher. The temperature and salinity decreased to 100–170 °C and 0–15 eq. wt.%, respectively, when the hydrothermal fluid activities were gradually ending. No distinct evolution pattern based on the homogenization temperature or stable isotopic analyses is observed among the different mineralization stages. Mineralization was supposed to be related to the multi-phased boiling of fluids, instead of the gradual cooling of fluids. Pressure may be more critical than temperature in controlling the precipitation of molybdenite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coexistence of sulphate and sulfides minerals, pore space breecia and alteration pattern arise questions. • Mixing model of previous studies has been challenged by the aforementioned evidence. • High-temperature fluid inclusions point out condensation of single-phase vapor. • H-O isotope highlighted the insignificant role of meteoric waters. • The questions justified with gas plume model. The Kahang deposit (100 Mt at 0.6% Cu) is one of the important porphyry copper deposits in the central part of Urumieh-Dokhtar Magmatic Arc (UDMA), Iran. The mineralization occurs as chalcopyrite and molybdenite in quartz and anhydrite -bearing veinlets or breccias and is closely associated with sericitic and phyllic alterations. Through comprehensive studies of the deposit's anatomy, some previously overlooked evidence raised new questions about the ore-forming process in the Kahang deposit. The coexistence of sulfate and sulfide minerals as veinlets and breccias, pore space breccias, could not be justified solely based on a previously introduced concept (i.e., mixing high temperature-high salinity magmatic water with low temperature-low salinity meteoric water). Fluid inclusions were examined in quartz veinlets of the A1, A2, and B types, anhydrite veinlets, and sphalerite of the L type veinlets. There are three types of fluid inclusions: liquid-rich (L-type), vapor-rich (V-type), and hypersaline (H-type). According to microthermometry of fluid inclusions, the fluids associated with anhydrite veinlets have relatively high temperatures (390–495 °C, mean = 455 °C) and low salinities (12.8–20.9 wt% NaCl equiv.) On the contrary, temperatures below 400 °C justified the coexistence of sulfate and sulfide minerals. The low solubility of anhydrite in high-temperature waters, on the other hand, demonstrates the gas–solid reaction of SO 2 (g) and plagioclase at such temperatures, as evidenced by fluid inclusions. Additionally, the fluid inclusions in quartz veinlets generated temperatures (290 to >600 °C) higher than those in the majority of other porphyry copper deposits. H-O isotopes indicated that magmatic fluids dominated, and meteoric waters played an insignificant role. These findings and observations supported the formation of the Kahang porphyry copper deposit as a result of a gas plume and the reactions of gas species with plagioclase to form anhydrite and sulfide minerals, as well as the formation of sericitic alteration in the host rock as a novel scenario. [ABSTRACT FROM AUTHOR]

[Display omitted] • Detailed observations combined CL imaging reveal three generations quartz in ore stage. • The key factor for the precipitation of Au was H 2 O-CO 2 -NaCl fluid immiscibility. • H-O isotopic data show ore fluids were mainly derived from magmatic fluids. • The Rb-Sr isochron age of gold-bearing pyrites is 128.1 ± 2.7 Ma. • The Hekou gold deposit shares similar mineralization feature with Jiaodong gold ore cluster. The Wuhe area in eastern Anhui province, hosting 23 metric tons of gold, has been recognized as a new gold ore cluster in the North China Craton (NCC) since the Hekou gold deposit was discovered in 2017. Its metallogenic setting and ore-forming process remain unclear. In this contribution, we perform a combined geology, cathodoluminescence, fluid inclusion, H-O isotope and pyrite Rb-Sr geochronologic studies on the Hekou gold deposit of the Wuhe area. In order to perform detailed fluid inclusion petrography study, we used scanning electron microscope-cathodoluminescence (SEM-CL) on a well preserved sulfides-bearing quartz grain from the auriferous quartz vein. In this quartz grain, generation A barren quartz in the core zone (Q A , CL-white), minor sulfides bearing generation B (Q B , CL-light gray) in intermediate zone and sulfides rich generation C (Q C , CL-dark gray) in the distal zone and fractures were revealed. Only in Q C , the higher carbonic proportion (50–80 vol%) inclusions (C C) coexist with the two-phase liquid-rich aqueous fluid inclusions (L C) and sulfides, meanwhile the C C and the L C show a similar Th of 258–313 °C and 249–308 °C, but different salinities of 1.4–5.3 wt% NaCl equivalent and 6.0–10.9 wt% NaCl equivalent, respectively. It suggests that dominating fluid immiscibility recorded in Q C is responsible for the prime deposition of gold and sulfide minerals. The δ18O (-4.1 to −6.5‰) and δD (-67.1 to −81.3‰) values of fluid inclusions in quartz suggest that ore-forming fluids were mainly derived from magmatic water which could related to mantle source. Gold-bearing pyrites yield an Rb-Sr isochron age of 128.1 ± 2.7 Ma, which is 8 m.y. earlier than the peak value of gold mineralization ages (ca. 120 Ma) at Jiaodong in response to the Early Cretaceous lithospheric thinning of the NCC and the reactivation of the Tan-Lu Fault zone (TLFZ). The Wuhe area shares similar characteristics of geology, fluid inclusions, H-O isotopes, and ore-forming ages with the Jiaodong gold ore cluster, highlighting the exploration potential in this region. [ABSTRACT FROM AUTHOR]

• The Xiadian ore and alterated rock are enriched in HREE, HFSE and transition elements. • The H-O and He-Ar isotopes are similar to the local enriched mantle-derived fluids. • The Sr-Nd-Pb isotopes suggest deeply sourced fluids interacted with Neoarchaean basement. • The new data do not support fluids and metals direct release from subducted sediments. The Jiaodong Peninsula is the largest gold concentration district in China and the third largest one in the world. It covers no >0.2% of China's total landmass yet accounts for 30% of the total national gold reserves with total proved resources near 5000 t Au. One wonders where all this gold comes from. Here we present detailed whole-rock element and Sr-Nd-Pb isotope, quartz H-O isotope and pyrite He-Ar isotope geochemical data for the Xiadian gold deposit, a large Jiaojia-type gold deposit in the Jiaodong district, which furnishes new constrains on the sources of ore-forming fluids and metals. The results indicate that the ore and alterated rock have much higher HREE (e.g. Yb and Y), HFSE (e.g. Nb, Ta, Zr and Hf) and transition elements (e.g. Sc, Ti, V, Cr, Co and Ni) than the host granites but similar to the lithospheric mantle-derived lamprophyres, suggesting an enriched lithospheric mantle origin. The H-O isotopes (δD V-SMOW = −93.9‰ to −102.3‰, δ18O H2O = −0.2‰ to 1.6‰) of fluid inclusions in quartzs collected from auriferous pyrite–sericite–quartz altered rocks are distinctly different from either primary magmatic water and metamorphic water or meteoric water in the Jiaodong district but similar to the local enriched mantle-derived fluids. The He-Ar isotopes [3He/4/He = 0.58 × 10−6 to 1.90 × 10−6 (0.42–1.36 Ra), 40Ar/36Ar = 725–1358] of fluid inclusions in pyrites collected from auriferous pyrite–sericite–quartz altered rocks are also similar to the local enriched mantle-derived fluids. The ore and alterated rock have distinct Nd-Pb isotopic compositions either from the host Linglong granites or from the asthenosphere-derived mafic dikes but similar to the lithospheric mantle-derived mafic dikes. Their Sr isotopic compositions show a mix trend between the lithospheric mantle-derived mafic dikes and Neoarchaean basement. All the elemental and multiple isotopic features support a metallogenic model that the ore-forming fluids and metals were derived from the local previously enriched lithospheric mantle, and such deeply sourced fluids may have interacted with Neoarchaean basement along their flow path and mixed with a little meteoric water when they arrived high levels in the crust. [ABSTRACT FROM AUTHOR]

The quartz-vein-type Baiyinhan tungsten deposit is located at the eastern part of the Central Asian Orogenic Belt, NE China. Analyses of fluid inclusions, H-O isotope of quartz and Re-Os isotope of molybdenite were carried out. Three stages of mineralization were identified: The early quartz + wolframite + bismuth stage, the middle quartz + molybdenite stage and the late calcite + fluorite stage. Quartz veins formed in the three stages were selected for the fluid inclusion analysis. The petrographic observation and fluid inclusion microthermometry results revealed three types of fluid inclusions: CO2-H2O (C-type), liquid-rich (L-type) and vapor-rich (V-type). The homogenization temperatures of C-type, V-type and L-type inclusions were 233–374 °C, 210–312 °C, and 196–311 °C, respectively. The salinity of the three types of inclusions was identical, varying in the range of 5–12 wt%. The H-O isotope analyses results showed that quartz had δ18OH2O and δDSMOW compositions of −2.6‰ to 4.3‰ and −97‰ to −82‰, respectively, indicating that the ore-forming fluids were mainly derived from magmatic water with a minor contribution of meteoric water. The addition of meteoric water reduces the temperature and salinity of the ore-forming fluids, which leads to a decrease of the solubility of tungsten and molybdenum in the fluids and eventually the precipitation of minerals. Re-Os isotopic analysis of five molybdenite samples yielded an isochron age of 139.6 ± 7.6 Ma (2σ) with an initial 187Os of −0.05 ± 0.57 (MSWD = 3.5). Rhenium concentrations of the molybdenite samples were between 3.1 ug/g and 8.5 ug/g. The results suggest that the metals of the Baiyinhan deposit have a crust origin, and the mineralization is one episode of the Early Cretaceous tungsten mineralization epoch which occurred at the eastern part of the Central Asian Orogenic Belt. [ABSTRACT FROM AUTHOR]

• Zircon dating yielded an Early Cretaceous pyrophyllite alteration timing. • Isotopes suggest a magmatic source of the volatile-dominated pyrophyllite fluids. • The pyrophyllite fluids are extremely acidic and highly oxidized. • The pyrophyllite alteration is the root zone of advanced argillic lithocaps. Genesis of pyrophyllite alteration can provide important clues for ore prospecting due to its various relationships with metallic mineralization. The Baiyun pyrophyllite deposit in the central Taihang Mountain (CTM) of the North China Craton (NCC) provides a natural case to gain insights into the genesis of pyrophyllite alteration and its relationships with gold mineralization in the wall rocks. The pyrophyllite ores primarily occur as subparallel-sheeted veins in fractures of the late Archean meta -volcanic rocks, and locally as filling fractures within the meta -intrusions. Phyllic alteration halos around the pyrophyllite orebody decline outwards, where gold mineralization develops as disseminated aggregates in honeycomb-like pyrites. Pyrophyllite ores are mostly dominated by 1TC-type pyrophyllite, sericite and quartz with minor kaolinite, illite and albite as identified by XRD analyses. Zircon grains from the granitic porphyry in the ore field define a weight mean U-Pb age of 130 ± 1 Ma (MSWD = 1.8, n = 19), and those from the sericite quartz schist yield an upper intercepted U-Pb age of 2551 ± 8 Ma. Zircon grains from the pyrophyllite ore yield an upper intercepted U-Pb age of 2566 ± 11 Ma and a lower intercepted age of 136 ± 7 Ma (MSWD = 0.99; n = 20), reflecting a Mesozoic magmatic-hydrothermal event, which could possibly be triggered by the lithospheric destruction of the NCC. LogƒO 2 -pH diagram suggests the fluids responsible for pyrophyllite alteration are extremely acidic (pH = 2.20) and under high oxygen fugacity (>ΔHM + 2.14). Calculated H-O isotopic compositions (δD H2O = −34 to −20‰; δO H2O = 3.4 to 7.5‰, 270 °C; δO H2O = 0.2‰ ~ 4.3‰, 200 °C) of pyrophyllite ores display typical features of volatile-dominated fluids with minor impact of meteoric water. Metal concentrations of pyrophyllite ores decrease with increasing contents of SiO 2 , suggesting the fluids generating pyrophyllite alteration are not conductive to gold mineralization. The results herein indicate that the Baiyun pyrophyllite deposit, formed as magma degassing in deep, are similar to the common root zones of advanced argillic lithocaps (barren shoulders) from porphyry environments and probably be the signs for erosion of epithermal deposits at shallow crustal depths. [ABSTRACT FROM AUTHOR]

The Shangfang deposit is a recently discovered large-scale tungsten deposit (66,500 t at 0.23% WO3), which is located near the western boundary of the Southeastern Coastal Metallogenic Belt (i.e., Zhenghe–Dafu fault), and adjacent to the northeast of the Nanling Range Metallogenic Belt. Unlike many other W–Sn deposits in this region that occur within or near the granites, the orebodies in the Sangfang deposit all occur within the amphibolite of Palaeoproterozoic Dajinshan Formation and have no direct contact to the granite. In this study, we carry out a thermal ionization mass spectrometer (TIMS) Sm-Nd isotope analysis for the scheelites from the orebody, which yields a Sm–Nd isochron age of 157.9 ± 6.7 Ma (MSWD = 0.96). This age is in good agreement with the previously published zircon U–Pb age (158.8 ± 1.6 Ma) for the granite and the molybdenite Re–Os age (158.1 ± 5.4 Ma) in the deposit. Previous studies demonstrated that the W–Sn deposits occurring between Southeastern Nanling Range and Coastal Metallogenic Belt mainly formed in the two periods of 160–150 Ma and 140–135 Ma, respectively. The microthermometry results of fluid inclusions in scheelite and quartz are suggestive of a near-isothermal (possibly poly-baric) mixing between two fluids of differing salinities. The H–O isotope results illustrate that the ore-forming fluids are derived from magma and might be equilibrated with metamorphic rocks at high temperature. The Jurassic granite pluton should play a critical role for the large hydrothermal system producing the Shangfang W deposit. Furthermore, the negative εNd(t) of −14.6 obtained in the Shanfang scheelite suggests for the involvement of the deep crustal materials. In general, subduction of the paleo-Pacific plate caused an extensional tectonic setting with formation of the Shangfang granites and related W mineralization, the geological background of which is similar to other W deposits in the Nanling Range Metallogenic Belt. [ABSTRACT FROM AUTHOR]

• The ore-forming fluids are dominant by magmatic signature with diluting of meteoric waters. • The magmatic-hydrothermal system occurred at a minimum depth of about 0.9 km. • The hydrothermal fluids boiled intensively during the early and main ore stage. • Initial hydrothermal fluids exsolved from the evolved tonalite magma with high oxygen fugacity. • The f O2 variation, fluid dilution and cooling contributed to abundant precipitation of sulfides. The Tuwu deposit (557 Mt at 0.58% Cu) is the most typical and economically significant one of several porphyry copper deposits in the Dananhu-Tousuquan Arc Belt near the Turpan-Hami Basin, northwest China. The mineralization occurs as chalcopyrite and minor bornite in quartz-bearing veins and host porphyries (i.e. diorite porphyry and tonalite porphyry), and is closely associated with potassic (e.g. K-feldspar, magnetite, and hematite) and phyllic (e.g. sericite, pyrite, albite and chlorite) alterations. Fluid inclusions were studied in different generations of quartz, defined as Qz IA+IB , Qz II , Qz III , and Qz IV. Four types of fluid inclusions were recognized, namely liquid-rich biphase (L 0), vapor-rich biphase (V 0) and triphase (V 1 , with one opaque mineral), as well as brine-rich (B 0 ; with or without an opaque mineral) inclusions. Based on fluid inclusion microthermometry using FIA method, the fluids associated with Qz IB (early ore stage) are characterized by relatively high temperatures (306–458 °C) and salinities (50.3–62.1 and 6.5–22.6 wt% NaCl + CaCl 2 equiv. for B 0 and L 0 inclusions, respectively), under lithostatic pressure of 167 to 444 bars (depth of 0.6–1.6 km), and the fluids associated with Qz II and Qz III (main ore stage) have progressively decreasing temperatures from 201° to 345 °C, under hydrostatic pressure of about 90 bars (depth of 0.9 km), which induced to large-scale mineralization at Tuwu. Mineralogy and physicochemical calculations suggest that the early stage occurred at alkaline and high-oxidized fluid environment (pH = 9.6 to 11.5; log f O2 = −26.4 to − 24.3), whereas the main ore stage took place at acidic and low-oxidized conditions (pH = 4.0 to 5.0; log f O2 = −30.8). The fluids associated with Qz IV (late ore stage) show low homogenization temperatures (<204 °C) and salinities (0.6–4.2 wt% NaCl + CaCl 2 equiv.), implying addition of meteoric water. The δ18O values of quartz and chlorite separates range from 7.7 to 12.1‰ (n = 21), with the calculated δ18O fluid values of − 5.4 to 9.0‰, and the δD values of fluids range from −99 to −45‰. All these observations combined with previous geochronological and geochemical results reveal that the Tuwu deposit was formed by magmatic-hydrothermal fluids related to the Late Carboniferous felsic magmatism (i.e. tonalite porphyry magma) in a subduction setting. The Cu concentration in magma source is probably the key factor controlling the anomalous Cu mineralization at Tuwu, and the oxygen fugacity and temperature decreasing of the fluids resulted in abundant precipitation of Cu-riched sulfides. [ABSTRACT FROM AUTHOR]

The Sizhuang gold deposit with a proven gold resource of >120 t, located in northwest Jiaodong Peninsula in China, lies in the southern part of the Jiaojia gold belt. Gold mineralization can be divided into altered rock type, auriferous quartz vein type, and sulfide-quartz veinlet in K-feldspar altered granite. According to mineral paragenesis and mineral crosscutting relationships, three stages of metal mineralization can be identified: early stage, main stage, and late stage. Gold mainly occurs in the main stage. The petrography and microthermometry of fluid inclusion shows three types of inclusions (type 1 H2O–CO2 inclusions, type 2 aqueous inclusions, and type 3 CO2 inclusions). Early stage quartz-hosted inclusions have a trapped temperatures range 303–390 °C. The gold-rich main stage contains a fluid-inclusion cluster with both type 1 and 2 inclusions (trapped between 279 and 298 °C), and a wide range of homogenization temperatures of CO2 occurs to the vapor phase (17.6 to 30.5 °C). The late stage calcite only contains type 1 inclusions with homogenization temperatures between 195 and 289 °C. With evidences from the H–O isotope data and the study of water–rock interaction, the metamorphic water of the Jiaodong Group is considered to be the dominating source for the ore-forming fluid. The ore-fluid belonged to a CO2–H2O–NaCl system with medium-low temperature (160–360 °C), medium-low salinity (3.00–11.83 wt% NaCl eq.), and low density (1.51–1.02 g/cm3). Fluid immiscibility caused by pressure fluctuation is the key mechanism in inducing gold mineralization in the Sizhuang gold deposit. [ABSTRACT FROM AUTHOR]