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Copyright of Geology & Resources is the property of Geology & Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The recently discovered 460 Gaodi porphyry Mo-Cu deposit is a sub-economic deposit characterized by low Mo-Cu grades, dispersed mineralization, and separated Mo- and Cu-ore bodies. This study aims to elucidate the factors underlying this type of sub-economic mineralization. Electron-microprobe analyses of biotite from ore-related granite porphyry yielded Ti-in-biotite crystallization temperatures of 677–734 °C (an average of 719 °C) and biotite phenocryst crystallization depths of 6.0 to 12.9 km. LA-ICP-MS analyses of zircons from the same sample revealed average zircon Ce4+/Ce3+ ratios of 299.7 and elevated zircon lg(ƒO2) ratios, with an average ΔFMQ of +6.6 ± 1.9. These discoveries suggest that the magma responsible for ore formation boasts a high degree of oxidation, yet also possesses a magma chamber located at a significant depth within the upper crust. This implies an extensive exsolving depth for fluids. Furthermore, our microthermometry analysis of fluid inclusions reveals that a portion of the fluid experiences considerable conductive cooling as it ascends along the conduit, owing to the depth of fluid exsolution. This process results in the ore fluids remaining in the liquid-only region without undergoing boiling, which is conducive to the enrichment of metals. We emphasize the fact that fluid-exsolving depth plays a critical role in determining the metal grades and economic value of a porphyry deposit by regulating the P-T evolution path of the ore fluids [ABSTRACT FROM AUTHOR]

The evolutionary process and spatiotemporal variation of W and Pb−Zn mineralizing fluids was investigated for the Subok deposit, a representative W−Pb−Zn deposit in the Hwanggangri mineralized district (HMD) in South Korea. The deposit was emplaced in Paleozoic carbonate rocks, which were intruded by Cretaceous Muamsa granite. The paragenetic sequence is characterized by early pyrrhotite-scheelite-arsenopyrite and late arsenopyrite-sphalerite-galena assemblages. In terms of spatial distribution, pyrrhotite and scheelite were dominant in the lower part, whereas arsenopyrite mainly occurred in the upper part. The upward increasing δ34SH2S values of ore-bearing fluids range from 1.0 to 5.9‰, corresponding to a magmatic origin. In this deposit, according to As content of arsenopyrite, fluid inclusion, and sulfur stable isotope, the early W and late Pb−Zn mineralization was controlled by decreasing temperature (425–590 to 380–450 °C), pressure (0.54–5.13 to 0.38–3.99 kbar), and sulfur fugacity of the uprising ore-bearing fluids. In the HMD, wolframite and molybdenite mainly occur in the granitic rock, whereas scheelite is precipitated in the carbonate host rock under decreasing oxygen fugacity, salinity, and pH, and the input of Ca from the host rock in the distal area. Late Pb−Zn mineralization was achieved by decreasing temperature and pressure of ore-bearing fluids and mixing with meteoric water in the distal area. The mineral zonation and physicochemical variation of W and Pb−Zn mineralizations can be applicable as indicators for the exploration of ore deposits. [ABSTRACT FROM AUTHOR]

Revealing hydrothermal evolution from the early oxide to late carbonate stages for quartz–wolframite vein‐type deposits is essential for understanding the ore‐forming process. In this study, we choose the Baishitouwa tungsten polymetallic deposit located in the southern Great Xing'an Range tungsten belt as a case study, and present detailed deposit geology and in situ fluid inclusion (FI) analyses including microthermometry, laser Raman spectra, and LA‐ICP‐MS microanalysis to address this issue. Four stages of hydrothermal activity were identified: (1) quartz–wolframite (I), (2) quartz–wolframite (II)–pyrite–chalcopyrite, (3) quartz–polymetallic sulphides, and (4) quartz–carbonate. Four types of FIs were recognized: CO2‐rich, CO2‐bearing, liquid‐rich, and brine inclusions. Microthermometric data showed that the homogenization temperatures and salinities from the early to late stages are 380–460°C, 7.4–17.3, and 29.3–43.2 wt% NaCl equiv., 300–390°C and 7.1–17.0 wt% NaCl equiv., 220–320°C and 2.7–8.1 wt% NaCl equiv., and 150–250°C and 0.5–4.8 wt% NaCl equiv., respectively, suggesting a decreasing trend. Geochemically, all stage fluids contained high Rb and Mn concentrations, high Rb/Na, Cs/Na, Li/Na, K/Na, Rb/Sr, low K/Rb, and consistent Cs/Rb and Cs/(Na + K) ratios, indicating that the mineralizing fluids originated from a common source—an underlying, geochemically uniform, and highly fractionated granitic magma. Fluid immiscibility and cooling are the main mechanisms for wolframite precipitation, whereas greisenization is subordinate; the incursion of meteoric water into the hydrothermal system initiated at the sulphide stage, and fluid mixing is the dominant mechanism for sulphide precipitation. [ABSTRACT FROM AUTHOR]

This article discusses the impacts of overprinting of tectonic and plutonic events on the mineralization of the Duna Pb-Ba ore deposit, according to geologic settings and fluid inclusion studies. The Duna carbonate-hosted deposit contains a significant amount of Ag (18.9-264.3 ppm), Cu (77-41600 ppm), Sb (32.7-11000 ppm), Sr (63.5-15100 ppm), and Fluid inclusions with 7.34-23.65 wt.% NaCl equivalent. The homogenization temperature of about 110-285°C, as well as the paragenesis of the minerals shows a difference compared with other Pb-Zn deposits such as the Irish-type and MVT. The ore mineralization in the Duna mine occurred as stratabound, open space-filling, and along the brecciated fault zones. The concordant (stratabound) type of mineralization, with salinity and homogenization temperature of 18.54 to 23.65 wt.% NaCl equivalent, and 113°C to 165°C respectively, is usually typical of MVT-ore deposits, which in this area evolved during the Early Cimmerian orogeny and was later interrupted by mineralization along younger brecciated fault zones with salinity and homogenization temperature of 7.34 to 23.65 wt.% NaCl equivalent, and 113°C to 285°C respectively. This discordant mineralization, which occurred along the faults, formed by the end of the Late Cretaceous and during the Cenozoic as a result of the intrusion of a plutonic mass, and is comparable to the Irish-type ore deposits. [ABSTRACT FROM AUTHOR]

To shed light on the genesis of the Dongping deposit and reveal the behaviour of CO2, Au and other ore elements (e.g., Cu, Fe, Zn, As, Sb, Co etc.) in ore‐forming fluids, petrographic, microthermometric and synchrotron radiation X‐ray fluorescence (SRXRF) analyses of fluid inclusions were conducted. The ore‐forming fluid is characterized as an H2O‐CO2‐NaCl system with medium‐high temperatures and low salinity. Four mineralization stages are identified, namely, feldspar‐quartz (stage 1); pyrite‐white quartz (stage 2); sulfide‐smoky grey quartz (stage 3); and carbonate‐quartz (stage 4). Three types of inclusions were distinguished, based on fluid composition, phase assemblages and mode of homogenization. Type A: H2O‐rich fluid inclusions show 2 phases (liquid H2O (LH2O) + vapour H2O (VH2O)) at room temperature and homogenize to the liquid phase. Type B: H2O‐CO2 fluid inclusions contain 2–3 phases (liquid H2O (LH2O) + vapour CO2 (VCO2); liquid H2O (LH2O) + liquid CO2 (LCO2)); liquid H2O (LH2O) + liquid CO2 (LCO2) + vapour CO2 (VCO2)) at room temperature and homogenized to the liquid H2O phase. Type C: H2O‐CO2 fluid inclusions show 2 phases (liquid H2O (LH2O) + liquid CO2 (LCO2) at room temperature and homogenize to a critical state. CO2 is clearly more enriched in the fluid inclusions of stages 2 and 3 than in stage 1. Stage 1 is dominated by type A (H2O‐rich) inclusions with homogenization temperatures (Th) of 220–359°C and salinities of 1.1–3.1 wt% NaCl equivalent. Type B (CO2‐rich) inclusions gradually increase in stages 2 and 3. The Th range of type B inclusions in stage 2 is 241–397°C with salinities of 2.2–6.9 wt% NaCl equivalent; the Th range of type A inclusions is 217–373°C with salinities of 1.2–8.1 wt% NaCl equivalent. The Th range of type B inclusions in stage 3 is 215–361°C with salinities of 2.9–6.1 wt% NaCl equivalent; the range of type A inclusions is 158–351°C with a salinity of 0.7–5.5 wt% NaCl equivalent. Stage 4 is characterized by type A with Th of 151–250°C and salinities of 0.9–8.3 wt% NaCl equivalent. The mapping results show that elements As, Te and Sb are more concentrated in vapour CO2 than in liquid H2O at room temperature, which suggests that vapour components are more able to transport elements when phase separation occurs. The SRXRF quantitative results show that Au, Cl, S and some other metals are obviously more enriched in the fluid inclusions of stages 2 and 3 than those in stage 1. Additionally, the contents of S in stages 1–3 are much lower than those of Cl, which suggests that gold might migrate mainly in the form of a gold‐chloride complex. Au is more enriched in type B fluid inclusions than in type A fluid inclusions, which suggests that the enrichment and migration of gold are closely related to CO2 and CO2 plays a critical role in the migration and enrichment of gold. The trace elements in the fluid have a similar change trend to those in the Yanshanian syenogranite distributed in the southeastern part of the mining area, which may provide some evidence for an intrusion‐related genesis for the Dongping gold deposit. [ABSTRACT FROM AUTHOR]

In order to investigate the influence of abnormal thermal fluid activity and late uplift of Qinghai-Tibet Plateau on the deep oil reservoir in front of Al-tun Mountain in Qaidam Basin, this paper adopts the techniques of microscopic observation and fluid inclusion analysis to analyze the effect of thermal fluid activity on hydrocarbon accumulation through the homogenization temperature test, combined with the paleo-tectonic movement, and to restore the process of hydrocarbon accumulation and late secondary transformation. The results showed that bitumen developed in the reservoir and high temperature inclusions were generally developed in the formation, which was obviously higher than the fluid inclusions temperature found by scholars in the study area. Quantitative grain fluo-rescence analysis of group inclusions showed that the reservoir was in the high maturity stage. During the accumulation history of Xianshuiquan reservoir in western Qaidam Basin, it experienced the transformation of abnormal thermal fluid activities, which promoted the rapid maturation of source rocks and the formation of highly mature high-temperature oil and gas inclusions, which had a certain destructive effect on the oil and gas reservoirs. This is closely related to the late strong tectonic movement of the Qinghai-Tibet Plateau and the late strike-slip action of the Altun Mountains. It also confirms that the western Qaidam Basin has experienced a strong uplift since 5Ma, and the deep oil reservoirs in the western Qaidam Basin have experienced the characteristics of crude oil charging and late secondary transformation. [ABSTRACT FROM AUTHOR]

The Choghart and Chadormalu iron deposits in Bafq metallogenic zone in Central Iran are classified as Kiruna-type deposits and surrounded by metasomatic rocks which Russian experts named them metasomatite. These rocks include different types of acidic to mafic igneous rocks and sediment and metamorphic rocks known as metasomatic bedrocks. The enrichment pattern of LREEs compared to HREEs in the spider diagrams is consistent with the felsic and alkaline nature of magma in the Choghart and Chadormalu deposits. Also, the negative anomaly of Nb and Ta and the positive anomaly of Th could be an important geochemical indicators for magmas produced in subduction zones. These metasomatic rocks formed as a result of the earliest and the deepest sodic metasomatism, multi-stage calcic metasomatism, and younger potassic metasomatism. The origin of the fluids responsible for metasomatism and alteration is magmatic, and these processes occur at a pressure of 40 MPa and a maximum depth of 2 km. The hydrothermal fluids have had an intermediate temperature and low salinity resulted in the sodic and primary calcic alteration and originated from the gabbro-diorite intrusive masses. The circulation of the high-salinity and high-temperature fluids has caused the next calcic alteration which can be related to a magmatic-hydrothermal origin which is associated with felsic magmatism in the region. The high-temperature potassium-containing fluids derived from intermediate to felsic magmas flowed towards shallow depths and caused potassic alteration. In the last stage of alteration, the release of calcium-rich hydrothermal fluids with low temperature and salinity created subsequent alteration after the main mineralization phases. [ABSTRACT FROM AUTHOR]

Copyright of Boletín Geológico y Minero is the property of Instituto Tecnologico Geominero De Espana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There are a large number of natural gas shows in the Upper Paleozoic of the central Hunan Basin. However, the hydrocarbon accumulation process was complicated due to the strong tectonic reformation in this area. A study of the natural gas accumulation period is of significance for determining gas accumulation models. In this research, the fluid inclusion samples were tested, the fluid inclusion occurrence characteristics, uniform temperature data, and reservoir evolution were analyzed, and four diagenetic periods and four diagenetic periods and three hydrocarbon accumulation periods were identified. (i) For the syntaxial stage, the filling is dark and nonluminous, and the fluid captured by the overgrowing cement around the particles is mainly seawater; (ii) for the (Early) Mesogenetic burial stage, the calcite cement grows around the particles or micritic calcite matrix, and the fluid captured is mainly brine; (iii) for (Late) Mesogenetic burial stage, two sets of decomposed fissures developed in massive calcite colloids with non-luminous gas-rich hydrocarbon inclusions within the crystals; and (iv) for Telogenetic burial stage, weakly fluorescent pure gaseous hydrocarbon inclusions are developed in luminescent calcite veins. The result indicates that the organic inclusions in the Lower Carboniferous of the central Hunan Basin are dominated by weakly fluorescent and nonfluorescent rich gas inclusions and pure gas-phase inclusions, with three stages of hydrocarbon filling. By integrating the average homogenization temperatures on burial curves, the three charging orders correspond to 260–250 Ma during the Late Permian, 249–245 Ma during the Early Triassic, and 208–170 Ma during the Late Triassic. Dense reservoir characteristics reveal deep basin gas reservoir in deep basin.

The Haxi gold deposit located in the Hatu–Saertuohai metallogenic belt of the west Junggar region, China, is a newly discovered gold deposit with proven reserves of ∼10 tons of gold and an average grade of 6.70 g/t. Primarily, the deposit is hosted in the early Carboniferous Tailegula Formation, controlled by the NEE-trending Anqi fault. The gold ore bodies contain gold-bearing quartz veins and altered basalt. The ore mineral is dominated by abundant sulfides, such as pyrite, arsenopyrite, chalcopyrite, and a little gersdorffite. To date, three types of fluid inclusion in quartz veins have been identified: liquid–gas (V-type), CO2–H2O (C-type), and liquid–rich (L-type). The ore-forming fluids exhibit medium homogenization temperatures (Th) of 226 °C–325 °C with low salinities of 2.24–9.34 wt% NaCl equivalent and low densities from 0.72 to 0.88 g/cm3. The δD values range from −115.3‰ to −100.7‰, with an average value of −109.1‰; the δ18O values range from 11.3‰ to 12.2‰, with an average value of 11.8‰; and the δ34S values in sulfide range from 0.3‰ to 1.8‰, with an average of 1.2‰. The average values of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in sulfide are 18.059, 15.547, and 37.996, respectively. To summarize, the metallogenic fluids were derived not from a single source but from late magmatic–hydrothermal fluid mixed with paleo-atmospheric water; furthermore, the ore-forming materials principally originated from a crust–mantle mixed source. The Pb model age calculated using Hautman’s formula is 347–365 Ma, leading to the speculation that the metallogenic period may be Devonian–Carboniferous.

An equation of state (EOS) of CH4-N2 fluid mixtures in terms of Helmholtz free energy has been developed by using four mixing parameters, which can reproduce the pressure-volume-temperature-composition (PVTx) and vapor-liquid equilibrium (VLE) properties of CH4-N2 fluid mixtures. The average absolute deviation of all the PVTx data available up to 673.15 K and 1380 bar from this EOS is 0.38%. Combining this EOS of CH4-N2 fluid mixtures and the EOS of CH4-CO2 and CO2-N2 fluid mixtures in our previous work, an EOS of CO2-CH4-N2 fluid mixtures has been developed, which is named ZMS EOS. The ZMS EOS can calculate all thermodynamic properties of ternary CO2-CH4-N2 fluid mixtures and the average absolute deviation of the PVTx data from the ZMS EOS is 0.40% for the CO2-CH4-N2 system. The ZMS EOS can be applied to calculate excess enthalpies of CO2-CH4-N2 fluid mixtures, predict the solubility of CO2-CH4-N2 fluid mixtures in brine and water, and quantitatively estimate the impact of the impurities (CH4 and N2) on the CO2 storage capacity in the CO2 capture and storage (CCS) processes. The ZMS EOS can also be applied to calculate the isochores of CO2-CH4-N2 system in the studies of fluid inclusions. All Fortran computer codes and Origin drawing projects in this paper can be obtained freely from the corresponding author. [ABSTRACT FROM AUTHOR]

The crystal structure of a birefringent garnet (~Adr53Grs47) that occurs as a late-stage rim on andradite from Stanley Butte, Graham County, Arizona is analyzed and refined using single-crystal XRD. The structure has an orthorhombic I 2/a 1 2/d (unconventional setting for Fddd) space group symmetry, with unit-cell parameters of a = b = 11.966(3) Å, c = 11.964(3) Å, α = β = 90°, γ = 90.29(2)°, V = 1713.0(7) Å3, Z = 8. The orthorhombic garnet displays very high birefringence (δ ~0.021) produced by the strong Fe-Al ordering in the octahedral sites, with Fe occupancies of 0.804 and 0.221 in Y1 and Y2 sites, respectively. Difraction peaks (such as 101 and 103) violating the Ia3̅d symmetry of cubic garnet are obvious even in powder XRD pattern. The homogenization temperatures of the fluid inclusions suggest that the low-crystallization temperature is responsible for the ordered orthorhombic structure. The strong ordering state of the structure and the sharp boundaries in the chemical zoning in the crystal (between ~Adr53Grs47 and ~Adr100) indicate the orthorhombic intermediate grandite garnet is a thermodynamically stable phase at low temperature, separated by wide miscibility gaps from the pure end-members (grossular and andradite) with cubic structures. Most of the previously reported triclinic garnet structures are likely artifacts produced by pseudo-merohedral twinning of less-ordered orthorhombic structure, as indicated by the characteristic pairing pattern of different Y-sites with the same occupancies. [ABSTRACT FROM AUTHOR]

Nim Ka Thana Copper Belt, in Rajasthan, India is well-known for the bornite dominated copper deposits. The present study area covers three prospects, i.e., Nanagwas, Dariba North, and Toda-Ramliyas, located in the central to the southern part of the belt. The sulfide mineralization is hosted within the carbonaceous phyllite and banded impure marble of the Paleoproterozoic sequence of the Delhi Supergroup but copper mineralization is only hosted within the banded impure marble. In this study, we use mineral chemistry of sulfide minerals, fluid inclusion of quartz vein, and sulfur isotopic geochemistry to decipher the genesis of sulfide mineralization. Nim Ka Thana copper belt exhibits a wide range of Ca-Na–K-B metasomatism. Mineral chemistry of pyrite and pyrrhotite shows Co/Ni ratio varies between 0.20–20 and 0.19–15 respectively. Three types of fluid inclusions are observed within mineralized quartz veins and homogenized within the temperature range of 121.5 °C to 390.1 °C and salinities of 0.33 wt% to 16.80 wt% NaCl equivalents. The homogenization temperature and salinity indicates the isothermal mixing and simple cooling of the ore-forming fluids and they are of metamorphic origin. Sulfur isotopic composition of major sulfides shows a bimodal distribution of δ34SVCDT (‰) values ranging from − 37.85‰ to + 6.33‰. It indicates that the ore-forming metals and sulfur come from a mixed source that encompasses sedimentary and hydrothermal sources. Based on field observation, ore mineral chemistry, petrographic study, fluid inclusion, and sulfur isotope study, it is inferred that the sulfide mineralization is overprinting of sedimentary and hydrothermal origin but copper mineralization is formed by the hydrothermal process. [ABSTRACT FROM AUTHOR]

The Lower Cretaceous Bayingebi Formation at the Hari sag, Northern China is a significant bearing oil-gas tight reservoir in the Yin'E Basin. In order to understand petrophysical properties of the reservoirs, the diagenesis and hydrocarbon accumulation phases were investigated using casting thin sections, scanning electron microscopy (SEM), X-ray diffraction and fluid inclusion analysis. Additionally, the histories of burial evolution, organic matter thermal evolution and hydrocarbon charge are investigated. The results showed that the pore types include primary pore, intergranular pore and dissolution intragranular pore. The diagenesis of sandstone reservoirs in the process of burial and diagenesis mainly includes compaction, fracture, cementation, metasomatism and dissolution. The comprehensive analysis of various diagenetic stage indexes shows that Bayingebi Formation is in the middle diagenetic stage A-B. The homogenization temperature and salinity of fluid inclusions are low temperature and low salinity (120 °C ∼ 130 °C, 0% ∼ 9%), medium temperature and high salinity (140 °C ∼ 150 °C, 10% ∼ 17%) and high temperature and medium salinity (160 °C ∼ 170 °C, 9% ∼ 11%) respectively. According to the homogenization temperature of the inclusions and the history of burial evolution, the Bayingebi Formation has mainly three phases of hydrocarbon accumulation (100 ∼ 97Ma, 93 ∼ 87Ma, 84 ∼ 81Ma). [ABSTRACT FROM AUTHOR]

Cassiterite (SnO 2), the principal ore mineral of tin, is mainly formed in granite-related magmatic hydrothermal systems. The precipitation mechanism of this mineral in hydrothermal veins is still debated due to lack of direct constraints on this specific mineralization process. Here, we present a detailed reconstruction of fluid evolution history from a high-grade cassiterite-quartz vein in the Weilasituo Sn-polymetallic deposit, North China, based on combined SEM-CL imaging with fluid inclusion microthermometry, Raman and LA-ICP-MS analysis of intergrown cassiterite and gangue minerals. Formation of the cassiterite-quartz vein at Weilasituo started from early topazization and muscovite deposition along vein walls and was followed by crystallization of topaz, quartz (Q1) and cassiterite in a general sequential order. Cassiterite deposition occurred within a restricted time period before complete crystallization of topaz and quartz. Shortly after cassiterite precipitation, the vein was fractured and overprinted by later quartz generations (Q2 & Q3) and fluorite. In situ microanalysis on primary and/or pseudosecondary fluid inclusions from the different crystallization stages indicates that an acid and reduced single-phase magmatic fluid of gradually dropping temperature but very consistent salinity was responsible for vein formation. Mixing of this magmatic fluid with a biotite-plagioclase gneiss buffered, deep-cycled underground water of lower temperature and salinity occurred at the final stage, but it is not related to Sn mineralization. The physical and chemical changes of fluids bracketing cassiterite deposition demonstrate that cassiterite precipitation at Weilasituo was predominately induced by the cooling of the hydrothermal fluid by at least 50 °C, and it is accompanied by the oxidation of Sn(II)-Cl complexes with CO 2 and/or As(III) species as potential oxidants. Early stage fluid-rock interaction with feldspathic host rocks and the formation of muscovite coverage on the vein walls are perhaps important for providing a fluid-buffered environment ideal for such mechanism. However, our result argues against meteoric water mixing or fluid boiling being the triggers of cassiterite deposition, and this conclusion has been further supported by cassiterite oxygen isotope analysis on the same set of samples. Additionally, the maximum base metal endowment (Pb and Zn) calculated from initial metal contents of the premineralization fluid at the Weilasituo Sn-polymetallic deposit are far less than proven reserves found in the two adjacent base metal deposits, and therefore a genetic link between these deposits is not suggested. This finding may have important implications for the ongoing exploration in the ore district. [ABSTRACT FROM AUTHOR]

There are many celestine deposits and mineralization points in the Huayingshan ore district which form the largest strontium resource base in China. Among these celestine deposits, the Yuxia and Xinglong are two of the larger deposits. Previous studies have displayed different views on the genesis of the celestine deposit in the Huayingshan ore district. In this study, we conducted field obversions, geochemistry, and fluid inclusion studies to investigate the sources of ore-forming matters and the metallogenic mechanism of the celestine deposit. Four types of fluid inclusion (FI), namely PL (pure liquid FI), PV (pure vapor FI), L-V (liquid-vapor two-phase FI), and L-V-S (liquid-vapor-solid three-phase FI) have been identified in celestine from different types of ore in the Xishan anticline. The ore-forming fluids belong to the NaCl-H2 O system with moderate to low temperature (190–220 °C) and moderate salinity (5–9 wt%, NaCl equiv.). Different types of ores were formed by the same period of hydrothermal activity, which is supported by the results of the microthermometer study. Geological, thermometric data, and published hydrogen and oxygen isotope results indicate that the hot brines associated with mineralization mainly originated from meteoric water and some of diagenetic fluid. The Sr (87Sr/86Sr = 0.7076–0.7078) and S (δ34S = 36.4–39.0) isotope values of celestine are consistent with those of the Jialingjiang Formation, indicating that ore metals in hot brines were predominantly derived from that formation. In situ analysis of celestine shows that there is a strong negative correlation between Sr and CaO (R2 = 0.95) and combined with mineralogical and isotope geochemical evidence, we concluded that the precipitation mechanism of celestine is the replacement of gypsum with Sr-rich hot brines. Based on the above research and the classification of celestine deposit type, we classified the celestine deposits in Huayingshan as being of hydrothermal type. The formation of celestine deposits can be divided into three periods: (1) evaporation period, forming the source bed; (2) hydrothermal activity period, forming celestine by replacement of gypsum with Sr-rich hot brines; (3) supergene period, where meteoric water dissolves orebodies and strontianization occurs. [ABSTRACT FROM AUTHOR]

The halogenesis of the Messinian Tuz Gölü Basin corresponds to the sulfate type and the magnesium sulfate subtype. Compared to the Messinian Sea brines, they have a slightly higher [Na+] concentration, which is 96.6–116.4 g/L, and a much lower [K+] concentration, ranging from 0.1 to 2.35 g/L. During salt sedimentation, the [Mg2+] concentration ranged from 6.1 to 14.0 g/L, and the [SO42−] concentration from 18.2 to 4.5 g/L. Physical–chemical reactions in the basin's near-surface and bottom waters during the suspension of halite deposition had a decisive influence on the significant reduction of [SO42−] sedimentation brines. During these periods, there was an intensive influx of Ca(HCO3)2 into the sedimentation basin and the formation of glauberite layers. The formation of the glauberite resulted from the slow dissolution of pre-deposited finely dispersed metastable minerals—gypsum, sodium syngenite, or mirabilite. In fluid inclusions in the halite, the sulfate minerals being allogenic crystals of calcium sulfate, are represented by gypsum, bassanite, and anhydrite. Additionally, as the other sulfate minerals, glauberite, anhydrite, and thenardite are found within halite crystals. Sharp fluctuations in daytime air temperatures characterized climatic indicators of the summer period in the Tuz Gölü region: 15.6–49.1 °C. In the spring or cool summer–autumn period, the daytime air temperature in the region ranged from 15.7–22.1 °C, and in late spring and early summer, it ranged from 20.6 °C to 35.0 °C. During some periods, the Tuz Gölü halite crystallized at 61.8–73.5 °C. The extreme high-temperature crystallization regime at the bottom of the salt-bearing basin was achieved due to the emergence of a vertical thermohaline structure. The "greenhouse effect" in the Tuz Gölü was established only briefly but was periodically renewed due to the influx of "fresh" waters. [ABSTRACT FROM AUTHOR]

The Zildat ophiolitic mélange lies in the eastern part of Ladakh and represents the part of the Indus Suture Zone. This ophiolitic mélange constitutes low-grade metasediments, ultramafic rocks, and exotic limestone blocks. The exotic blocks are comprised of calcite, which shows various type of twinning patterns that indicates dynamic recrystallization up to 300 °C. The carbon and oxygen isotope ratio of the exotic block is 3.2 ± 1.1‰VPDB and 21.7 ± 2.8 ‰VSMOW, respectively, suggestive of marine/platform origin. Furthermore, the stable isotope (carbon and oxygen) ratio of CO2 and H2O fluid also advocates the platform type origin of the fluid. Two types of fluid inclusions were observed in these exotic blocks: carbonic and aqueous-carbonic entrapped between 435 and 370 °C at 386–323 MPa and advocates for deep-seated marine carbonates and exhumed from 13 km depth below the sea surface which become got deposited in the Zanskar shelf. The exotic blocks in ophiolitic mélange were probably derived from the Zanskar shelf (platform), having salinity between 20.37 and 11.22 wt % NaCl, similar to the Permian time seawater. [ABSTRACT FROM AUTHOR]

Methane (CH4) is a critical but overlooked component in the study of the deep carbon cycle. Abiotic CH4 produced by serpentinization of ultramafic rocks has received extensive attention, but its formation and flux in mafic rocks during subduction remain poorly understood. Here, we report massive CH4-rich fluid inclusions in well-zoned garnet from eclogites in Western Tianshan, China. Petrological characteristics and carbon–hydrogen isotopic compositions confirm the abiotic origin of this CH4. Reconstructed P–T– f O2–fluid trajectories and Deep Earth Water modeling imply that massive abiotic CH4 was generated during cold subduction at depths of 50–120 km, whereas CO2 was produced during exhumation. The massive production of abiotic CH4 in eclogites may result from multiple mechanisms during prograde high pressure-ultrahigh pressure metamorphism. Our flux calculation proposes that abiotic CH4 that has been formed in HP-UHP eclogites in cold subduction zones may represent one of the largest, yet overlooked, sources of abiotic CH4 on Earth. [ABSTRACT FROM AUTHOR]

The material source and the evolution of ore-forming hydrothermal fluids of Xiaojiashan gold deposits remain controversial. We carried out a mineralogical characteristics analysis, trace elements analysis, sulfur isotope composition analysis, and fluid inclusion microthermometry in order to explore the ore-forming sources, conditions, and process of this deposit. Gold mineralization can be divided into three stages: the quartz-pyrite stage, the quartz-polymetallic sulfide stage, and the quartz-ankerite stage. This gold deposit was probably formed under the following conditions: temperature of 122–343 °C and salinity of 0.8–11.4 wt% (NaCl). It was inferred that the ore-forming hydrothermal fluids were early metamorphic–hydrothermal (Stage I) and late magmatic–hydrothermal (Stages II and III), and were characterized by medium–low temperature and medium–low salinity based on fluid inclusion microthermometry and S isotope composition. The temperature and salinity of the ore-forming fluid decreased during mineralization, which was caused by the involvement of groundwater. The chondrite-normalized trace element patterns of the gold ores are similar to the host rocks of the Lengjiaxi Formation, indicating that the ore-forming materials were sourced from the Lengjiaxi Formation. The S isotopes indicated that the magmatic components also provided the ore-forming materials during Stages II and III. [ABSTRACT FROM AUTHOR]

The Miocene Daralu Porphyry Copper Deposits (PCDs) is found associated with other porphyries such as Sarcheshmeh and Meiduk in the Kerman Cenozoic Magmatic Arc (KCMA), southern Iran. In this research, we provided whole-rock geochemical data, characteristics of hydrothermal fluid and sulfur isotope composition of the Daralu intrusive body, and discussed the nature, tectonic setting and fluid evolution of this deposit aiming to investigate its fertility. The Daralu porphyry shows adakites affinity, that is, high Sr/Y and La/Yb ratios and positive Eu anomalies. The REEs patterns indicate a strong fractionation ([La/Yb]n= 28.73). High La/Sm and Dy/Yb ratios suggest enrichment of amphibole and garnet as residual phases in melt source, whereas partial melting of plagioclase increases Eu and Sr in the parent magma. The presence of garnet implies a pressure equivalent to the thickness of more than 40km of crust. To elucidate the evolutionary history of fluids and the origin of the Daralu deposit, we focused on the origin and composition of the fluid through petrography, Raman spectroscopy, and microthermometry studies of fluid inclusions. The fluid inclusions have been divided into four types: vapor (type I), aqueous-vapor (type II), CO2-bearing (type III), and multiphase (type IV). The Raman shifts included 1284 and 1388 cm-1 for CO2 and 2750-3900 cm-1 for H2O. The events such as NaCl supersaturation, exhausting of CO2-rich components, high oxygen fugacity and temperature decreasing through mineralization stages were critical in controlling the fertility of the Daralu PCD. The obtained δ34S data for sulfides yielded an average of +5.5‰. Based on the observed features, it was concluded that Daralu porphyry shares formation conditions with other productive porphyries of the KCMA. [ABSTRACT FROM AUTHOR]

Gold mining in Western Borneo can be traced back over a century in the Dutch era. Many of these gold deposits are hosted in auriferous quartz veins, yet their geology and alteration/mineralization features have never been well documented. In this study, we present the first detailed account on gold mineralization in Western Borneo, using the Monterado goldfield as an example. Our results reveal that the auriferous quartz veining occurred in both intrusions (Mensibau granodiorite and Sintang Suite diorite porphyry) and volcanic‐sedimentary sequences (Raya Volcanics and Hamisan Formation), and wallrock alterations are well developed. Distributions of the veins are controlled largely by N‐S‐trending (tensional veins, e.g., Nek Rimban and Muisan) and NW‐SE (en‐échelon tensional gash veins, e.g., Mertua, Lipan, and Sekar) structures. Vein textures include mainly massive, breccia, comb, drusy, and stockwork. Advanced Mineral Identification and Characterization System mineral mapping on the ore veins and mineralized wallrocks show the presence of electrum, acanthite, pyrite, chalcopyrite, bornite, sphalerite, galena, and supergene products such as malachite, covellite, cuprite, chalcocite and rosasite. Polymetallic sulfide mineralization is spatially associated with adularia within auriferous quartz veins and silicic alteration. Ore chemistry on 285 vein ore samples yielded on average 1.46 g/t Au and 6.58 g/t Ag. Fluid inclusion microthermometry indicates that the homogenization temperature ranges from 273 to 362°C (avg. 338°C), with salinities of 1.1–8.7 wt% NaCl eq. (avg. 4.4 wt% NaCl eq.). Accordingly, the Monterado Au–Ag quartz vein‐type mineralization is best classified as intermediate‐sulfidation epithermal style. [ABSTRACT FROM AUTHOR]

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Introduction Varmazyar Pb–Zn (Ag) occurrence, 65 km north of Zanjan, is located in the Tarom–Hashtjin metallogenic belt (THMB). The THMB has been recognized as one of the most important epithermal metallogenic belts in Iran (Kouhestani et al., 2018b) that host numerous small- to medium-sized epithermal deposits (i.e., Gulojeh, Aqkand, Aliabad–Khanchy, Chodarchay, Khalyfehlou, Chargar, Zajkan, Marshoun, Abbasabad, Zehabad, and Shah Ali Beiglou). These epithermal deposits are temporally and spatially related to late Eocene granitoids (Mehrabi et al., 2016; Kouhestani et al., 2018b). Although the general geological characteristics of the region, where the Varmazyar occurrence is located, were determined (Faridi and Anvari, 2000), no detailed studies have been conducted on the mineralogy, geochemistry, and the ore-forming fluids characteristics of the Varmazyar occurrence. In this paper, we investigate the geology, mineralogy, geochemistry, fluid inclusions, and alteration styles of the Varmazyar occurrence to constrain its ore genesis. These results may have implication for the regional exploration of epithermal deposits in the THMB. Materials and methods Detailed field work has been carried out at different scales in the Varmazyar area. A total of 70 samples were collected from various parts of ore veins and breccias, host tuff units and granitoid intrusion. The samples prepared for thin (n=15) and polished-thin (n=27) sections in the laboratory of University of Zanjan, Zanjan, Iran. Representative 7 samples from the mineralized veins and breccias, 1 sample from host intermediate tuff unit and 1 sample from barren and fresh granite intrusion, were analyzed for rare and rare earth elements using ICP–MS in the Zarazma Analytical Laboratories, Tehran, Iran. Fluid inclusion measurements have been conducted on 4 doubly polished thick (~150 μm) sections including crystalline quartz, and sphalerite from the second, and third stages of ore formation. Microthermometric measurements were performed using a Linkam THMSG-600 heating–freezing stage attached to a ZEISS microscope in the fluid inclusion laboratory of Iranian Mineral Processing Research Center, Tehran, Iran. Results and Discussion The geological units hosting the Varmazyar occurrence are mainly Eocene volcanic and volcaniclastic rocks that were intruded by late Eocene granitoids. The volcaniclastic rocks can be divided into two units as acidic (lithic tuff, lithic crystal tuff and crystal tuff) and intermediate (lithic crystal tuff, crystal tuff, and lithic tuff) units. They are metamorphosed to clinopyroxene hornfels facies near contact intrusions. The granodiorite intrusion is the main rock units in the Varmazyar area. It crops out mainly in the south, southwest and northeast of the Varmazyar occurrence. It ranges in composition from monzogranite to syenogranite and shows porphyritic and granular textures. Mineralization at Varmazyar occurs as epithermal base metal quartz-sulfide brecciated vein that occupy NS-trending faults in the Eocene acidic and intermediate tuff units. The ore vein extends up to 300 m along, from several cm to 2–3 m wide, and generally dip steeply (65–80°) to the west. Wall-rock alterations developed at the Varmazyar occurrence include silicification, intermediate argillic, carbonate, and propylitic alteration; the first three are closely related to the Pb–Zn (Ag) mineralization. The alteration styles show a systematic zonation pattern, from the silica, via intermediate argillic, to propylitic alteration. Four stages of mineralization can be distinguished at Varmazyar. Stage 1 is represented by silicification of host rocks along with minor disseminated pyrite. This stage is a pre-ore stage and usually crosscut by later stages. Stage 2 is the main ore-stage at the Varmazyar occurrence. It is characterized by up to 5 cm wide quartz veins and breccias that contain variable amounts of disseminated galena, sphalerite, and minor pyrite. Clasts of this stage and associated wall-rock alteration have been recognized in the hydrothermal cements of stage 3 breccias. Stage 3 is marked by quartz-calcite-manganese oxides (psilomelane, pyrolusite, braunite) veins and breccia cements. It is usually crosscut previous mineralization stages and, in turn, is cut by stage 4 calcite veinlets. Stage 4 is a barren post-ore stage represented by < 1 mm wide calcite veinlets. This stage usually crosscuts previous ore stages. No sulfide minerals are recognized with stage 4. The ore minerals at Varmazyar formed as vein-veinlet and hydrothermal breccia cements, and show disseminated, vein-veinlet, brecciated, comb, crustiform, colloform, cockade, bladed, plumose, and vug infill textures. Galena, sphalerite, pyrite, psilomelane, and pyrolusite are the main ore minerals; smithsonite, cerussite, goethite, secondary pyrolusite, and braunite are supergene minerals. Quartz, calcite, and sericite are present in the gangue minerals. Comparison of Chondrite–normalized rare elements and REE patterns of host intermediate tuffs, barren and fresh granite intrusion, and the mineralized samples at Varmazyar indicate that mineralization is probably genetically related with granite intrusions. In this case, leaching of some elements from the host tuff units may have involved in mineralization. Ore-forming fluids associated with the quartz-sulfide veins are represented by two-phase aqueous inclusions and by H2O–NaCl fluids with moderate-temperature (135–249 °C) and low-salinity (0.2–6.4 wt.% NaCl equiv.). Fluid inclusion data indicates that fluid boiling and mixing were important processes in the evolution of the ore-forming fluids at Varmazyar. Our data suggest that Varmazyar is an example of intermediate-sulfidation type of epithermal base metal mineralization.

A giant fault-controlled oilfield has been found in the ultra-deep (greater than 6000 m) Ordovician carbonate strata in the northern Tarim Basin. It is of great significance for hydrocarbon accumulation study and oil exploitation to determine the key oil accumulation periods. Based on detailed petrographic analysis, fluid inclusion association (FIA) in calcite samples filling in fractures from 12 wells were analyzed, and key accumulation periods of the strike-slip fault-controlled oilfield was studied by combining oil generation periods of the source rocks, formation periods of the fault and traps, and the fluid inclusion data. (1) There are multiple types of FIA, among them, two types of oil inclusions, the type with yellow fluorescence from the depression area and the type with yellow-green fluorescence from the uplift area with different maturities indicate two oil charging stages. (2) The homogenization temperature of the brine inclusions in FIA is mostly affected by temperature rises, and the minimum temperature of brine inclusions symbiotic with oil inclusions is closer to the reservoir temperature during its forming period. (3) FIA with yellow fluorescence all have homogenization temperatures below 50 °C, while the FIA with yellow-green fluorescence have homogenization temperatures of 70–90 °C tested, suggesting two oil accumulation stages in Middle–Late Caledonian and Late Hercynian. (4) The Middle–Late Ordovician is the key formation period of the strike-slip fault, fracture-cave reservoir and trap there. (5) The oil generation peak of the main source rock of the Lower Cambrian is in the Late Ordovician, and the oil accumulation stage is mainly the Late Ordovician in the depression area, but is mainly the Early Permian in the uplift area. The key oil accumulation period of the strike-slip fault-controlled reservoirs is the Late Caledonian, the depression area has preserved the primary oil reservoirs formed in the Caledonian, while the uplift area has secondary oil reservoirs adjusted from the depression area during the Late Hercynian. Oil reservoir preservation conditions are the key factor for oil enrichment in the strike-slip fault zone of northern Tarim, and the Aman transition zone in the depression is richer in oil and gas and has greater potential for exploration and development.

Based on a combined in-situ calcite U-Pb dating, molecular geochemical correlations of reservoir oil and extract from reservoir rocks, and fluid inclusion analysis, the charge and evolution history of the YJ1X ultra-deep oil reservoir of the Ordovician Yijianfang Formation in the southwestern part of the Tabei Uplift has been determined systematically. (1) The reservoir oil, free oil and inclusion oil have similar geochemical characteristics and are presumably derived from marine source rock deposited in similar sedimentary environment. (2) The reservoir oil, free oil and inclusion oil have similar maturities with calculated equivalent vitrinite reflectance values in the range of 0.80%–0.96%. (3) Two types (Group I and II) of oil inclusion assemblages (OIAs) have been identified in the reservoir, of which Group I represents the original gas-saturated oil entering the trap during the initial oil charge, whereas Group II represents undersaturated residual oil retained in the reservoir after minor leakage of light hydrocarbon. (4) The reservoir experienced oil charge only once during the Early Devonian around 425 Ma and has been well preserved after the minor light hydrocarbon leakage in the Middle Devonian. The study shows that there may be old oil and gas accumulations in ultra-deep strata of petroliferous basins with well-developed caprock and stable tectonic background.

Finding direct records of the ancient Earth's atmosphere is key to understand the evolution of the entire planet. Nevertheless, such records are scarce, and only a few geological samples with preserved paleo-atmospheric signatures are available today. In this study, we analyzed noble gases contained in shocked granitic and volcanic rocks collected across the 380 Ma-old Siljan impact structure (in Sweden) to investigate the potential of shocked quartz crystals with planar deformation features (PDFs), often decorated by fluid inclusions, to preserve atmospheric signatures. Our results reveal that most of the investigated samples show relative elemental abundances of noble gases falling between those of air and meteoric water values. Atmospheric gases are present in the samples but excesses in radiogenic, nucleogenic, and fissiogenic noble gas isotopes highlight interactions of fluids with crustal rocks during the impact-generated hydrothermal circulation of fluids after the impact. Such fluid circulation event(s) could also have remobilized older fluids originally present in fluid inclusions preserved in the mineral lattices. Furthermore, results obtained on the two pure quartz fractions highlight a stronger atmospheric signature correlated with the presence of PDFs. The atmospheric component detected in this study could represent either a paleo-atmospheric signature trapped shortly after the Siljan impact event, or it may result from modern atmospheric contamination. Future studies of noble gases contained within shocked quartz crystals from other impact structures will unveil if such samples present advantages compared to other paleo-atmospheric proxies. [ABSTRACT FROM AUTHOR]

The metasedimentary rock succession of the Neoproterozoic-Cambrian Katanga Supergroup in the Central Africa Copperbelt shows evidence of several complex tectonic events. The deformation of this supergroup started from the tectonic inversion at about 570 Ma and lasted up to today, but reached paroxysm at ∼550 Ma. This long period was characterized by folding and faulting throughout multiple compressive and extensional events, which controlled the regional fluid flow on the one hand, and played an important role during formation of the stratiform to stratabound Cu-Co (Ni, U) deposits and the polymetallic Cu-Zn-Pb (Ag, Ge, Mo, Cd) vein type deposits on the other hand. Based on the structural analysis and paleostress reconstruction, coupled with fluid inclusion characterization from mineralized structures in rocks from the Nguba, Kundelungu and Biano Groups, this study demonstrates that the composition of hydrothermal fluids changed during brittle tectonic deformation during the Lufilian orogeny and subsequent uplift and post-Lufilian faulting. During early brittle tectonic deformation along strike slip faults with sinistral and dextral movement related to a NE-SW transpression, the Cu-mineralizing fluid was hypersaline (27.9–31.1 eq. wt% NaCl) with moderate temperatures (Th = 128–216 °C). The subsequent Cu or Cu (Zn, Pb) mineralization formed within an E-W extensional stress regime, related to the late Lufilian orogenic collapse. The fluid inclusions present in the gangue minerals associated with this latter mineralization show a large range in Th (50–264 °C) and salinity (26.7–36.0 eq. wt% NaCl). The decrease in temperature is interpreted to be due to migration of the fluids at shallower depth in the subsurface after uplift and erosion of the orogen. The increased salinity of the fluid is related to the dissolution of evaporites, mainly NaCl. A second H 2 O-NaCl-CaCl 2 fluid with a homogenization temperature below 55 °C has also been found associated with this brittle stage and mineralization phase, but only in rocks belonging to the Kundelungu Group. A third mineralization phase, also characterized by Cu or Cu (Zn, Pb), formed during the post-Lufilian period within a NW-SE transpressional inversion regime. The fluid inclusion in the gangue minerals of this mineralization phase have a smaller range in homogenization temperature (Th = 37–172 °C) and the largest range in salinity (0.71–30 eq. wt% NaCl), compared to the earlier fluid inclusions generations. This large range in salinity may be explained by the mixing of a high salinity fluid, already present during the earlier tectonic stages in the sedimentary basin, with meteoric water. During the more recent rift-related extension, a fluid with again a large and higher range in homogenization temperatures (Th = 47–257 °C) and with a typical low salinity (<10 eq. wt% NaCl) has been recognized in minerals filling NNE-SSW to NE-SW oriented faults and fractures. The upward migration of a relatively low-salinity fluid from deeper parts in the subsurface explains the variation in the temperatures observed with this tectonic event. [Display omitted] • Brittle tectonism and associated Cu-Zn-Pb mineralization in the Central African Copperbelt. • Syn-to post-orogenic high temperature, high salinity mineralizing fluids. • Salinity-temperature evolution of mineralizing fluids during cooling and uplift. • Post-orogenic mixing of high salinity mineralizing fluids with meteoric water. • Tectonism and fluid flow in the Neoproterozoic Katanga basin in Central Africa. [ABSTRACT FROM AUTHOR]

Sn and Cu are proposed to have their mineralization potential predetermined by their contents in initial fluids of granite-related magmatic-hydrothermal systems. However, it remains ambiguous whether the giant Sn-mineralized skarn system is applicable, and whether the Sn-Cu association in some deposits is predominantly determined by their initial metal contents. The Gejiu orefield is one of the most essential Sn-polymetallic districts worldwide, with proven resources of 3.27 million tons of tin, 3.25 million tons of copper, 4.29 million tons of lead and zinc, and >20 other metals with economic significance. Sn-polymetallic mineralization at Gejiu constitutes a composite skarn ore system that includes proximal skarn and related cassiterite-sulfide, greisen, and tourmaline-vein types. The Laochang Sn-polymetallic deposit hosts several largest skarn and cassiterite-sulfide orebodies in the eastern part of Gejiu. Recent exploitation at Laochang discovered Sn-mineralized quartz veins hosted in the concealed granite, providing a valuable opportunity to characterize the proximal magmatic-hydrothermal process of the mineralizing granitic system. Here, fluid inclusion analysis is carried out on these veins to discuss the fluid evolution, cassiterite precipitation mechanism and whether metal content in early proximal magmatic fluids determines the metal association and endowment in the deposit. Based on the paragenesis of ore and gangue minerals, three hydrothermal stages are distinguished, including quartz-tourmaline stage (Stage I), cassiterite-arsenopyrite-quartz stage (Stage II) and late sulfide stage (Stage III). Fluid evolution controlling vein formation is constrained by microthermometry and LA-ICP-MS analysis of four fluid inclusions generations successively entrapped in quartz and cassiterite. The fluids involved during vein formation show an interplay between single-sourced magmatic fluids and meteoric water. The intermediate-density single phase fluid recorded at stage I quartz is derived from initial fluids directly exsolving from granitic magma. At stage II, fluid immiscibility occurred and the separated brines were entrapped in quartz and early-formed cassiterite. Along with cassiterite precipitation, brines were mixed with low-salinity and cooler meteoric water, leading to entrapment of low-salinity aqueous fluid in outer growth zones of cassiterite at stage II. The constructed fluid evolution history suggests that fluid immiscibility may have facilitated the nucleation of cassiterite crystals at the onset of deposition while mixing of magmatic fluid with meteoric water likely dominate later cassiterite mineralization. Compared with the fluid dataset of barren and mineralized granitic systems worldwide, pre-ore fluids of the studied quartz veins are enriched in Sn, confirming that high Sn content in the initial magmatic fluid can serve as indicator to distinguish mineralized system. In contrast, although Cu mineralization is economically important in the Laochang deposit, predicted Cu contents in pre-ore proximal magmatic fluids are as low as those obtained from Cu-barren system. This implies introduction of Cu into the hydrothermal system from other sources. • Sn mineralization veins in Laochang are controlled by proximal magmatic fluids • Fluid immiscibility and fluid mixing in the vein probably facilitate cassiterite precipitation • Enrichment of Sn in pre-mineralization fluids is necessary for formation of Sn deposit • Significant Cu mineralization in Sn ores is attributed to introduction of Cu from other sources. [ABSTRACT FROM AUTHOR]

Interpreting the hydrocarbon generation, migration, and accumulation process is significant for understanding hydrocarbon evolution and finding exploration targets. The buried hills of Shulu Sag exhibit great potential for hydrocarbon exploration. However, the variations observed in different oil reservoirs highlight the complexity of hydrocarbon migration and accumulation in this region. In this study, 1D basin modeling, fluid inclusion analysis, and quantitative fluorescence techniques were used to investigate the thermal maturation history of the source rock, the timing of hydrocarbon charging, the pathway of hydrocarbon migration, and the oil-water contact. Hydrocarbons in the buried hills in the Western Slope and Paleo-uplift are derived from the source rocks at the edge and center of the sag, respectively, which have different thermal maturation histories. The source rocks in the center of the sag mainly supply hydrocarbons to the Paleo-uplift through faults, while the hydrocarbons generated from the source rocks in the edge of the sag can be rapidly transported to the Western Slope through clast-supported terrigenous carbonate rudstone. Differences in oil sources result in different hydrocarbon charging histories for the Western Slope and Paleo-uplift. The Western Slope experienced a single low-mature oil charging event at 5-0 Ma, while the Paleo-uplift encountered two hydrocarbon charging events, including low-mature oil charging at 35-25 Ma and high-mature oil charging at 5-0 Ma. As a result of secondary changes controlled by the hydrological environment, the oil reservoirs in the Western Slope have undergone varying degrees of adjustment or even destruction, resulting in variations in the oil quality of different buried hills. The results provide a detailed understanding of hydrocarbon migration and accumulation in the study area, which can be used as a reference for hydrocarbon exploration. • Quantitative fluorescence techniques were used to trace the migration pathway and identify oil-water contact. • Buried hills in the Western Slope and Paleo-uplift have different hydrocarbon charging histories. • Carbonate rudstone at the edge of the sag is a fast channel for hydrocarbon migration. • The adjustment of oil reservoirs is attributed to secondary changes controlled by water chemistry. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Dulong skarn-type deposit developed two stages of Sn mineralization. • Detailed fluid study suggest mixing is the main mechanism for Sn mineralization. • Difference of trace elements in two stages of cassiterite also imply a mixing trend. Dulong Sn polymetallic deposit is a world-class skarn tin deposit situated at the Youjiang basin with a reserve of 0.4 Mt Sn at 0.56 %, 5.0 Mt Zn at 5.12 %, together with 7 kt In. The deposit predominantly occurs within the Neoproterozoic Xinzhaiyan Formation and is controlled by NS-trending faults. Based on elaborate field and petrographic observations, the Dulong Sn polymetallic deposit was divided into four mineralization stages: stage 1 (prograde stage), stage 2 (retrograde stage), stage 3 (quartz-sulfide stage) and stage 4 (carbonate stage). Tin mineralization primarily occurs as cassiterite during stage 2, with additional cassiterite-stannite formation noted in stage 3. Analysis of fluid inclusions across these stages reveals the evolutionary history of the mineralizing fluids and the precipitation mechanisms at Dulong. During stage 1, diopside hosts both daughter-bearing multiphase inclusions and vapor-rich inclusions. The daughter-bearing multiphase inclusions exhibit homogenization temperatures ranging from 510 to 574 °C and salinities between 44.7 and 49.6 wt% NaCl equiv., whereas the vapor-rich inclusions display homogenization temperatures of 573–586 °C and salinities from 2.9 to 4.0 wt% NaCl equiv., indicating a boiling fluid process. Cassiterite (stage 2) features primarily liquid-rich two-phase inclusions, with homogenization temperatures of 351–410 °C and salinities of 6.3–9.6 wt% NaCl equiv. These inclusions document the mixing of magmatic fluid with meteoric water, which is likely the principal mechanism driving initial tin mineralization. Similarly, the same type of inclusions is also recorded in cassiterite of stage 3. The homogenization temperature of the inclusions in cassiterite is 290–334 °C and the salinities of the inclusions is 3.4–8.4 wt% NaCl equiv. Comparatively, the temperature continued to decrease in stage 3, indicating that fluid mixing may have persisted during this stage which could also explain the occurrence of cassiterite and stannite in this stage. In addition, redox reaction where CO 2 and/or As (III) serve as oxidants may also be another mechanism to exact cassiterite from ore-forming fluid. Our Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) data suggests that cassiterite of the Dulong deposit involves a variety of complex substitutional mechanism. Due to the differing geochemical properties of the elements and variations in their concentrations, there is an indication that two phases distinct mineralizing fluids may have been present. The varying geochemical properties and concentrations of elements such as Nb, Ta, Zr, Fe, In, and Ga align with microthermometric results, indicating a reduction in magmatic hydrothermal fluid contribution and/or a transition from high to low temperatures in the hydrothermal system. This variation is also likely attributable to fluid mixing processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ore-causative granodiorite of the Lianhuashan Cu deposit was emplaced at 252.8 ± 1.8 Ma. • Primary magmas of the adakite-like granodiorite originated from partial melting of the thickened lower crust following closure of the Paleo-Asian Ocean. • New fluid inclusion and H–O–S–Pb isotope data were obtained. • Ore fluids and metals were derived principally from a magma source. The medium-sized Lianhuashan Cu sulfide deposit is located in the southern Xing'an Range of Inner Mongolia, NE China. The zoned massive sulfide vein ores are hosted mainly in the Permian Dashizhai Formation, and the ore veins are controlled by NW–NNW-trending structures. The ore-forming process comprises four stages: arsenopyrite–quartz (I); chalcopyrite–pyrite–quartz (II); pyrite–chalcopyrite–sphalerite–galena–quartz (III); and ore-barren sulfide–quartz–carbonate (IV). Three types of fluid inclusions (FIs), namely vapor-rich two-phase (LV-type), liquid-rich two-phase (VL-type), and daughter mineral-bearing three-phase (SL-type), are distinguished. Stage I, II and III contain all types of FIs (LV-, VL-, and SL-type), with homogenization temperatures (Th) of 268–462°C, 230–382°C and 180–340°C and salinities of 3.4–52.3, 3.4–44.5 and 3.7–39.9 wt% NaCl eqv., respectively, whereas stage IV has only VL-type FIs, with Th = 152–232°C and salinity = 3.4–7.9 wt%. Fluid geochemical data show that the Lianhuashan ore fluids were of medium–high temperature (236–382 °C), high-salinity (31.5–44.5 wt%), and relatively oxidizing conditions, typical of a NaCl-H 2 O system. The microthermometric and H–O isotope data (δ18O H2O = − 9.0 to 6.1 ‰; δD = − 149.0 to − 99.0 ‰) indicate that the ore fluids were initially magmatic with later meteoric water incursion. The sulfide S (δ34S = − 2.9–3.8 ‰) and Pb (206Pb/204Pb = 17.954 − 18.492, 207Pb/204Pb = 15.427 − 15.739, 208Pb/ 204Pb = 37.815 − 38.357) isotopes support that the metals were magmatic-derived. Fluid boiling, cooling, and meteoric water mixing were likely the main ore precipitation mechanism at Lianhuashan. We suggest that Cu minerals at Lianhuashan were precipitated with boiling at ∼ 1 km depth. For the ore-forming granodiorite porphyry (zircon U-Pb age: 252.8 ± 1.8 Ma), geochemical data indicate that the primary magma was formed by partial melting of the thickened or delaminated lower crust. Integrating the available age, geological, and geochemical evidence, we suggest that mineralization at Lianhuashan is spatial–temporal and genetically associated with the granodiorite porphyry, and was formed in a volcanic arc setting after the Paleo-Asian Ocean closure. [ABSTRACT FROM AUTHOR]

[Display omitted] • Main mineralization stage of pyrite 1 & 2 distinguished by trace element chemistry of pyrite. • Elemental maps of pyrite exhibits Co, Ni zones distinguish early & later hydrothermal pyrite. • Ore forming fluids of CO 2 -H 2 O ± CH 4 of moderate salinity show fluid immiscibility. • δ 34S values represent crustal sources contributed to the Au mechanism. The Jiapigou auriferous belt in Jilin province has been recognized as substantial gold-producers in the North China Craton (NCC). Gold mineralization in this district mainly occurs in mineralized quartz veins and alteration zones, characterized by silicification, pyritization, and argillitization. The quartz veins contain three generations of mineralized quartz, namely, qtz1 (probably oldest), qtz2 (slightly younger), and qtz3 (probably youngest) were identified using SEM-CL. The fluid inclusions in all three generations of quartz are broadly of three types, viz., bi-phase Ia (H 2 O-CO 2), tri-phase Ib (H 2 O-CO 2 -NaCl ± CH 4), and II (H 2 O-NaCl).The micro-thermometric analysis of the type Ia and Ib fluid inclusion in qtz1 & qtz2 have aqueous-carbonic composition and exhibit a similar salinity of 1.1 to 7.8 wt% NaCl equivalent, whereas the homogenization temperature (Th) range varies from ∼237 to ∼350 °C. These ore-related fluid inclusions are of low to moderate salinity, and show mixture of CO 2 and CH 4. On the other hand, Type II fluid inclusions are dominant in qtz3. They have salinity of 3.2 to 12.7 wt% NaCl equivalent and homogenization temperature varying between 180 °C and 210 °C. These data indicate that the ore-forming fluid evolved from a CO 2 –H 2 O–NaCl ± CH 4 system during the mineralization period. The X-ray elemental maps of pyrite acquired using electron microprobe analysis (EPMA) show irregular zones of Co and Ni indicating two generations of pyrite. The early-stage pyrite which occupies core portion shows high Co and Ni, whereas the later-stage pyrite occupying rim has lower Co and Ni. The laser ablation-inductively coupled plasma-mass spectrometer (LA-ICPMS) analyses of pyrite has indicated that pyrite-1 is rich in Au + Ag + Se + Cu + Co + Ni, whereas, pyrite-2 has lower concentration of these elements. A positive correlation between Fe and other chalcophile elements reported here (i.e. Au + Ag + Se + Cu + Co + Ni), might be due to fluid-rock interaction resulting into a saturated fluid that subsequently precipitated along the microfractures within earlier-formed pyrite and quartz. The in-situ δ34S values in pyrite from Jiapigou deposits overlap in the range of +4.5 to +9.6 ‰, which is consistent with the ore-forming fluids of the crustal origin input during fluid-rock interaction. The systematic pyrite compositional observations and fluid inclusions study documented here to provide new insight into the process of ore formation for the Au enrichment in the Jiapigou deposit. [ABSTRACT FROM AUTHOR]

On the Biga Peninsula (NW Türkiye) Oligo-Miocene felsic plutonic intrusions extend vast regions. Skarn zones have developed around South Yenice plutons in this zone, which Show a rich potential for contact metamorphic diversity and mineralization, depending the host rock variety. Contact metamorphic zones and skarn occurrences have been mapped and determined. U Pb dating was performed on garnets, and ages of 25.26 ± 0.30 Ma and 26.01 ± 1.02 Ma were yielded from Islıkçatıdere, and 24.85 ± 1.68 Ma, 25.81 ± 3.97 Ma and 21.03 ± 0.38 Ma from Namazgah skarn zones, respectively. U Pb zircon dating of the Hıdırlar, Kurtlar and Namazgah plutons yielded ages of 26.33 ± 0.3, 25.39 ± 055 and 24.79 ± 0.38 Ma. These ages prove that the ages obtained from the skarn zone and the parent plutons are compatible. Garnet mineral chemistry and trace element analyses, when evaluated together with limited fluid inclusion data, indicate that the study area may be important in terms of potential iron, copper, lead and zinc mineralization. [ABSTRACT FROM AUTHOR]

The Cerattepe deposit is associated with bimodal felsic volcanics of the Kızılkaya Formation, which hosts the majority of VMS deposits in the Eastern Pontide Orogenic Belt. Pyrite, chalcopyrite, sphalerite, and bornite are the main sulfides, with minor galena, fahlores, marcasite, idaite, covellite, and chalcocite. Barite and quartz are the primary gangue minerals, with minor calcite and gypsum. Hematite, limonite, goethite, jarosite, and lepidocrocite are common oxide minerals. The sulfide ore is shaped by rapid cooling, zone refinement, replacement, and local deformation processes, which affect textural relationships and mineral paragenesis. Fluid inclusion studies have shown that the early stages of the ore were formed by boiling at temperatures of 250–355 °C and approximately 1900 m depth of sea water, while the later stages developed at temperatures as low as 148 °C. The Te temperatures imply that NaCl-dominated solutions with partial mixing of CaCl 2 may be responsible for mineralization. The CO 2 phase present in the early stages of the ore may have been derived from the interaction of hydrothermal solutions with the underlying carbonate rocks. Salinity values of 0.2–7.62 wt% NaCl equ., compatible with the average salinity of Kuroko type VMS deposits, indicate that the Cerattepe deposit was formed in a marine environment. The Co/Ni of pyrites (1–12, with an average of ∽2) and Zn/Cd of sphalerites (127–383) indicate an acidic source and magmatic source of acidic-andesitic for the ore-forming fluids, respectively. The δ34S values −4.4 ‰ – +9.63 ‰ indicate a magmatic sulfur source, with partial sulfate-reduced sulfur. A magmatic-related source is also inferred from δ18O values (+8.5 and + 9.5 ‰.) for the Cerattepe deposit. The leaching, zone refinement, and replacement processes, followed by remobilization and precipitation of the metals, resulted in gold enrichment in the oxide zone. The new zircon U Pb dating constrains the formation age of the Cerattepe deposit into a time span from 79 ± 1–76.8 ± 1 Ma, a younger age compared to other VMS deposits in the eastern Pontide region. [ABSTRACT FROM AUTHOR]

This study focuses on the evolution of the Kirazlıyayla volcanic-hosted Zn-Pb ± Cu epi-mesothermal vein-type deposit and its relationship to volcanism in NW Turkey. The Kirazlıyayla area has an extensive variety of geological formations, including the Karakaya, Yenipazar, Fındıcak, Sarısu Volcanics, and Mesudiye. The mineralization that formed within the Sarısu Volcanics at Kirazlıyayla mine area exhibits distinctive features, including the occurrence of crosscutting quartz and sulfide veins and veinlets, forming a network of sulfide-bearing stockworks with locally banded/bedded massive sulfide. Three mineralization phases occur across the alterations. Pyrite crystallization and silicification alteration occurred during the first phase. In the next phase, sphalerite develops with the deposition of the first generation of galena and chalcopyrite occurs along with sericite, kaolinite, and quartz in the phyllic alterations. Dolomite and calcite minerals dominate carbonatization in the third phase, with the second generation of galena and chalcopyrite with tennantite. The δ34S of the sulfides exhibited a range of values from 0.7 to 6.8 ‰ VCDT , with an average value of 2.13 ‰ VCDT. The presence of igneous rocks in the study area provides evidence for a uniform sulfur source having magmatic signature. The variability in sulfur isotope composition can be observed in intermediate and high-sulfidation ore minerals. The use of oxygen isotope analysis has the potential to facilitate the identification of hydrothermal fluids involved in the formation of ore deposits, which often exhibit a combination of magmatic and metamorphic fluids. The fluid inclusion investigations have shown two-phase liquid-vapor inclusions in both the sphalerite and quartz minerals, which could be categorized as both primary and secondary varieties. The indication of these fluid inclusions inside sphalerite and quartz implies a potential meteoric source and may be attributed to the gradual mixing of fluids responsible for ore formation, which is facilitated by the influx of meteoric water along the pathway of fluid flow. Therefore, these fluid inclusions show magmatic-meteoric mixing, resulting in the creation of low-salinity ore-forming fluids due to the interaction between magmatic fluid and diluted meteoric water, resulting in further mineralization at the late stage of mineralization. Zinc, lead, and copper in hydrothermal fluids may supersaturate under fluid mixing conditions, producing Zn-tennantite and second-generation galena minerals. In conclusion, the Kirazlıyayla deposit is influenced by a variety of physicochemical conditions associated with volcanism and the transportation of hydrothermal fluids. These fluids penetrate the crust, dissolving metals from nearby rocks, and may circulate and flow towards the surface via the NE-trending faults and fractures in the study area. When these hydrothermal fluids reach zones of lower pressure or temperature, mineralization often occurs, allowing dissolved metals to precipitate out of the fluid and create mineralized veins. Therefore, the volcanism played a significant role, both as a heat source and a mechanism for mobilizing hydrothermal fluids, enhancing the understanding of metallogenesis in NW Turkey. • This study focuses on the evolution of the Kirazlıyayla volcanic-hosted Zn-Pb±Cu epi-mesothermal vein-type deposit. • The mineralization hosted in Sarısu Volcanics includes sulfide-bearing stockworks within phyllic and propylitic alterations. • The δ34S data reveal sulfur having a magmatic source; the δ18O values imply a mixture of magmatic and metamorphic origins. • Fluid inclusion studies indicate the presence of a mixture of magmatic and meteoric fluids in the mineralized fluid. • Volcanism played a significant role, both as a heat source and a mechanism for mobilizing hydrothermal fluids. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wolframite in the Xuehuashan deposit yields a U-Pb age of 213.0 ± 6.7 Ma. • Trace elements in wolframite are controlled by crystalline chemical effects and initial fluids. • The ore-forming fluid is a single high-T magmatic fluid. • Decompression and boiling caused W precipitation. • Late Triassic highly evolved granitoids in the Qinling Belt have potential for W mineralization. The West Qinling Belt is a pivotal part of the Central China Orogenic Belt renowned for producing abundant Au-polymetallic deposits. Nonetheless, reports of wolframite mineralization within this region were absent. The Xuehuashan deposit is the premier documented quartz-vein type wolframite deposit in West Qinling, which has significant implications of W mineralizing potential in the West Qinling Belt. The ore bodies are predominantly composed of wolframite-quartz veins and/or veinlets which are proximal or within the Late Triassic Baijiazhuang granitoid. To elucidate the age and genesis of the Xuehuashan wolframite mineralization, we presented analyses of U-Pb dating and chemical composition on wolframite, fluid inclusion study, and hydrogen–oxygen isotopes on wolframite and quartz. The Xuehuashan wolframite U-Pb dating yielded an age of 213.0 ± 6.7 Ma, which is consistent with the age of the Baijiazhuang granitoid. The correlation among trace elements and the Y/Ho vs. Zr/Hf diagram suggests trace elements in wolframite were influenced by crystalline chemical factors and the geochemistry of parental ore-forming fluid. Homogeneous texture and stable chemical composition of wolframite, as well δD vs. δ18O isotopes, suggest a single magmatic fluid from the Baijiazhuang granitoid. Fluid inclusions in wolframite and quartz have high homogenization temperatures and varying salinities of 0.4 – 16.4 wt%, suggesting that intense decompression and fluid boiling during fracture open caused the wolframite precipitation. Compared with the Late Triassic granitoids in the Qinling Belt, the Baijiazhuang granitoid shows higher ratios of Rb/Sr and lower ratios of Zr/Hf, K/Rb, Nb/Ta, LREE/HREE, as well as negative Eu anomalies, which are consistent with the W-related highly evolved granitoids but distinct to W-barren granitoids. Hence, this study highlights W mineralization potential in the Qinling belt associated with the highly evolved Late Triassic granitoids. [ABSTRACT FROM AUTHOR]

Garnet–orthopyroxene granulites from the Rauer Islands (East Antarctica) provide a spectacular example to investigate the late fluid evolution, metamorphic duration, and behavior of monazite and zircon in response to metamorphic reactions and fluid–rock interaction. Here, we characterize the secondary fluid inclusions in peritectic garnet and orthopyroxene, which occur as multiphase inclusions along micro–fractures. Inclusions are composed of siderite, pyrophyllite, calcite, quartz and residual CO 2 , representing stepdaughter phases resulting from the interactions between C–O–H fluid and its hosts at variable temperatures during retrogression. Zircon grains show clear core–rim structure, which yield 206Pb/238U ages of 540–507 Ma and 527–490 Ma, respectively. Index inclusions and internal structures suggest that the cores document the timing of peak and post–peak decompression while the growth of rims corresponds to melt crystallization during the final cooling. The U Pb systems in zircons are considered to have not been obviously affected by fluid or melt–mediated modification. The unusual formation of monazites in garnet–orthopyroxene granulites may be linked with the elevated phosphorus budget as a result of apatite dissolution during the prograde melting of the rocks. Detailed investigations suggest that the crystallization of monazites occurred both at peak and post–decompression stages, whose isotopic systematics has been completely reset due to melt–mediated dissolution–precipitation. The spurious dates for monazites (522–495 Ma) are highly coinstantaneous with the dating results for zircon rims, further supporting this view. Therefore, we conclude that the late carbonic fluid influx cannot result in marked U(Th)–Pb resetting in zircon and monazite. Instead, anatectic melt may have played an important role in the disturbance of isotopic systematics in monazites, especially for long–lived high–grade metamorphic terranes. Combined with previously published data, we propose that the Pan–African metamorphic event in the Rauer Islands may have reached the peak at around ∼540 Ma, followed by a protracted post–peak evolution that lasted for at least ∼50 Myr. This study highlights the importance of an integrated investigation of fluid and index mineral inclusions, as well as the chemical signatures of zircon and monazite, to interpret chronological data correctly. • Secondary fluid inclusions are reported from the garnet-orthopyroxene granulites. • Peak metamorphism occurred at ∼540 Ma, and the UHT metamorphic event lasted for >50 Myr. • Monazite dates of 522–495 Ma may be spurious due to melt-mediated Pb-loss. [ABSTRACT FROM AUTHOR]

The Dawangzhuang buried hill zone is a typical representative of Paleozoic oil and gas exploration in the Jiyang Depression, Bohai Bay Basin, and has experienced a complicated accumulation process. Using petrographic observation, microthermometry and abundance of hydrocarbon inclusions, the Paleozoic hydrocarbon charging process in Dawangzhuang buried hill zone was discussed. The study shows that the Paleozoic reservoirs developed hydrocarbon inclusions in the study area. Ordovician hydrocarbon inclusions with pale yellow and blue-green fluorescence distributed along the calcite veins and particle healing joints. Asphalt inclusions and oleaginous are only distributed in Dagu 671 oil reservoir with a small scale. The main peaks of the homogenization temperature are from 80 ℃ to 90 ℃ and from 100 ℃ to 110 ℃; Carboniferous-Permian hydrocarbon inclusions with blue-green fluorescent distributed along the micro-cracks of quartz particles and secondary enlarged edges. The main peak of the homogenization temperature is from 100 ℃ to 110 ℃. Combining with the hydrocarbon generation and expulsion periods of source rocks, it can be concluded that there are two stages of hydrocarbon charging in the Paleozoic in the study area. The first stage of oil and gas charging occurred in the late Dongying period (27~25 Ma), which was a small-scale accumulation of Paleozoic, mainly in the Ordovician; the second stage of oil and gas charging occurred from the end of Guantao period to the end of Minghuazhen period (5~2 Ma), which was a large-scale accumulation of Ordovician and Carboniferous-Permian. The development of asphalt inclusions near the Dagu 671 well area and the fact shown by the Effective Grids containing Oil Inclusions (EGOI) that the ancient oil-water interface is lower than the current one are related to the activity of the Da 1 fault at the end of the Minghuazhen period (2 Ma), resulting in local adjustments and smaller scope of oil and gas reservoir.

The Wunugetushan large porphyry Cu–Mo deposit in NE China is hosted by Mesozoic quartz monzonite porphyry and has a Mo-rich core and Cu-rich rim in space. In this paper, melt inclusions in porphyry intrusions and fluid inclusions in different-stage quartz veins were studied to explore potential parameters leading to Cu–Mo decoupling. Melt inclusions in porphyry intrusions have rhyolitic compositions of 71.7–85.3 wt.% SiO2, 1.9–31.3 ppm Cu and 1.7–2.6 ppm Mo. Hydrothermal activity occurred over three stages: 1) Early Mo mineralization at high temperatures (543°C–560°C) and CO2-rich fluids of intermediate salinity (11.0–17.3 wt.% NaCl equivalent), accompanied by biotitization and minor K-feldspathization; 2) Late Mo mineralization involving high-salinity (up to 77.0 wt.% NaCl equiv.) oxidized fluids at intermediate temperatures (400°C–454°C), with K-feldspathization and minor sericitization; 3) A Cu-mineralization stage with high-salinity (up to 45.6 wt.% NaCl equiv.) and CO2-barren fluids characterized by temperature peaks at 250°C–300°C and 400°C–450°C, accompanied by sericitization and illitization. Given possible variations in melt Cu/Mo ratios during magmatic activity and redox conditions, pH, fluid composition, and temperature during the hydrothermal-fluid stage led to the separation of Cu and Mo, we found that integrated parameters including increased Cu/Mo ratios in residual melt, variations in the redox state and more acidic environment of hydrothermal fluids determine spatial separation of two metals.

Inorganic and organic fluids are widely found in sedimentary basins during oil and gas migration and accumulation. This research investigates two types of sandstone reservoirs with different pressure states and fluid evolution of the Shahejie Formation in the western slope belt of Dongpu Sag. Based on petrographic observations, micro-Raman spectroscopy, and fluorescent spectrometry, petroleum inclusions, CH4-bearing inclusions, and CO2-bearing inclusions were discovered in quartz-hosted minerals. The pressure–temperature–time–composition (P–T–t–X) properties of the CH4 and CO2 inclusions were obtained by quantitative Raman analysis and thermodynamic models. Minimum trapped pressure was predicted by the thermodynamic modeling of petroleum inclusions. Saffron yellow petroleum inclusions represent an early Oligocene oil-charging event (∼32–30 Ma), and the two kinds of reservoirs were all kept in moderate-overpressure conditions (average pressure coefficient: 1.26). Due to rapid uplift and denudation (Dongying movement) in the middle Oligocene in step II, crude oil degrades into CH4 and CO2 (density of CH4 gas inclusions: 0.1010–0.1339 g/cm3; density of CO2 gas inclusions: 0.450–0.612 g/cm3) and retains low-maturity (0.67–1.04%) bitumen in situ. Tectonic destruction causes the reservoir to be released to normal pressure. With the reburial of the Es3 Formation, step II entered the middle stage of oil generation again (average pressure coefficient: 0.90). However, in step I, with secondary hydrocarbons occurring, second-stage oil (performance for pale blue fluorescence in petroleum inclusions) accumulated at ∼12–0 Ma (late Miocene–Pliocene). The second oil charging event in step I remains a reservoir under high-overpressure conditions (average pressure coefficient: 1.67).

The Shibaogou deposit is located in the Luanchuan ore district within the East Qinling orogenic belt (EQOB), central China, which is a newly discovered Mo–Pb–Zn skarn deposit. The skarn and Mo–Pb–Zn ore bodies are mostly hosted in the contact zones between the Shibaogou porphyritic granite and carbonaceous sedimentary rocks from the Luanchuan and Guandaokou sets. A study combined of geochronology, fluid inclusion (FI), and stable isotopes was performed to constrain the mineralization age, source of ore materials, and the origin and evolution of the ore-forming fluids and their relationship with the subduction of the Paleo-Pacific Plate. The mineralization process includes skarn and quartz–sulfide episodes, which has four stages: skarn (I), quartz–molybdenite (II), quartz–galena–sphalerite (III), and quartz–calcite (IV). Molybdenite Re-Os dating suggests that the deposit was formed in the Late Jurassic (147.4 ± 7.2 Ma). Reportedly, there are five primary types of fluid inclusions: L-type, V-type, H-type, S-type, and C-type. In the skarn stage, coexisting H-type (35.58 wt%–46.05 wt% NaCl equiv.) and low-salinity V-type (0.35 wt%–5.7 wt% NaCl equiv.) fluid inclusions show similar homogenization temperatures, which suggests that fluid boiling occurred at 513–550°C and 580–650 bar (2.19–2.45 km). In the quartz–molybdenite stage, the homogenization temperatures of L-type, V-type, minor H-type, and S-type fluid inclusions indicate continued fluid boiling at 324–387°C and 180–250 bar (0.49–0.94 km). In the quartz–galena–sphalerite stage, a fewer number of coexisting V-type and L-type fluid inclusions in quartz shows different salinities with similar homogenization temperatures, indicating that they are trapped at 303–347°C and

In this study, petrographic, microthermometric, and synchrotron radiation X-ray fluorescence (SRXRF) analyses of fluid inclusions were conducted to shed light on the mineralization mechanism of the Dongtongyu deposit and provide some evidence of the relationship among CO2, Au, and other ore elements (e.g., Cu, Fe, Zn, and Pb) in ore-forming fluids. The ore-forming fluid is characterized as the H2O–CO2–NaCl system with medium–high temperatures and low salinities. Four structural mineralization stages are distinguished: Pyrite-quartz (Stage 1), gold-quartz-pyrite (Stage 2), gold-quartz-polymetallic sulfide (Stage 3), and quartz-calcite (Stage 4). Fluid inclusions in Stages 1–3 are dominated by the H2O–CO2 type, and most of them contain liquid H2O and liquid CO2 at room temperature. The melting temperatures (Tm-CO2 = −82.1°C to −57.5°C) of solid CO2 in Stage 1 are relatively low. The values of Tm-CO2 in Stages 2–3 are quite close, with ranges of −60.5°C to −56.5°C and −59.2°C to −58.6°C, respectively. The melting temperatures of clathrate in Stages 1–3 are −2.7°C to +7.8°C, −5.5°C to +7.8°C, and +3.7°C to +7.2°C. The homogenization temperatures of the CO2 phase in the H2O–CO2 inclusions of the three stages are measured as −7.5°C to +31.7°C, −7.5°C to +29.3°C, and 7.1°C to +24.1°C. The total homogenization temperatures in Stages 1–3 are 180°C–394°C, 202°C–305°C, and 224°C–271°C, with salinities of 4.3 wt.%–18.2 wt% NaCl, 4.3 wt.%–20.0 wt% NaCl, and 5.3 wt.%–11.0 wt% NaCl, respectively. The laser Raman spectroscopy results show that the CO2–H2O inclusions in the quartz veins contain abundant CO2 and CH4. The SRXFR results show that most of the elements, especially As, Te, and Cu, are more enriched in liquid CO2 than in liquid H2O. The elements of Au, Fe, Ni, Cu, and Pb have higher concentrations in H2O–CO2-type fluid inclusions in Stage 2 than other fluid inclusions in Stages 1–2, suggesting that gold mineralization is closely related to CO2-rich fluids. During the fluid evolution process, fluid immiscibility is an important mineralization mechanism of gold. The increase in CO2 and CH4 and the decrease in the fluid temperature might promote fluid immiscibility.

The oil and gas resources of the Middle Jurassic reservoirs in the Shengbei Sag of the Turpan Basin are widely distributed. A detailed analysis of the fluid inclusions and accumulation periods is beneficial to the fine exploration of oil and gas. Using inclusion petrography, fluorescence analysis, and microthermometry, the characteristics of fluid inclusions were analyzed in the Middle Jurassic reservoir of the Shengbei Sag to determine the formation and distribution of oil and gas reservoirs. Furthermore, the period of oil and gas accumulation of the tight sandstone reservoir was also investigated in the Middle Jurassic through burial history simulation and geothermal history simulation. The results show that a large number of hydrocarbon inclusions and secondary brine inclusions are developed in the Middle Jurassic reservoirs of the Shengbei Sag. The oil inclusions are usually beaded in bands or clusters within the healing cracks of quartz grain and through the quartz grain cracks, and their fluorescence color is mostly light yellow and blue-green, indicating mature and highly mature hydrocarbon charging in this region respectively. The gas inclusions do not fluoresce. The homogeneous temperature distribution of hydrocarbon inclusions and their coexisting brine inclusions has a wide range and is characterized by multi-episode distribution. Combing with burial history, geothermal history and thermal maturity history modeling, two accumulation periods are further identified in the Shengbei Sag. The first early period of hydrocarbon accumulation mainly occurred during the Late Jurassic to Early Cretaceous period, and the second late period of hydrocarbon accumulation took place during the Late Tertiary to present. This is consistent with that extracted from the hydrocarbon generation and trap formation. The research results are helpful in refining the sweet spots of tight oil and gas exploration and exploitation in the Middle Jurassic formation of Shengbei Sag, Tuha Basin. [ABSTRACT FROM AUTHOR]

Pegmatites from southwestern Nigeria have mostly been characterized using mineralization with few reported studies using the fluid inclusion approach for pegmatite genesis. This study was carried out to determine the origin, type, and characteristics of fluid inclusions in pegmatites from the Oke-Ogun and Ibadan-Osogbo pegmatite fields of southwestern Nigeria. Pegmatite samples were systematically collected at selected areas, 16 whole rock pegmatite samples and 32 mineral extracts were analyzed for their elemental concentration using inductively coupled plasma optical emission spectrometry, and pegmatitic quartz was used for microthermometric studies. Results (in ppm) revealed Be, Zn, Nb, Sn, Cs, W, and Ta ranged as 1.00–384.00, 30.00–3800.00, 0.60–330.00, 1.00–319.00, 0.70–475.00, 17.20–933.00, and 0.32–107.00, respectively. Plots of Ta vs K/Cs, K/Rb vs Rb, K/Rb vs Ba, Ta vs K/Cs, Rb vs Ba, and Ta vs Cs + Rb showed that the pegmatites were unmineralized to mineralized muscovite class pegmatites. Inclusions are aqueous, primary to pseudo-primary classified as type I, two-phase liquid–vapor (L + V; L > V), ~ 2–100 µm; type II, liquid + vapor + solid (L ± V + S), ~ 2–15 µm; and type III, monophase (liquid) at room temperature. The inclusions occurred as trails, clusters, and isolated inclusions. Type I inclusion had salinities of 0.7–21.9 wt.% NaCl eq. and all inclusions homogenized into the liquid phase at total homogenization (Th) of 80.1–335.1 °C. Fluid modeling revealed type II inclusion (Th 350 °C) was the earliest fluid trapped (at 250 °C), type I inclusion was trapped at 160–250 °C, and type III inclusions were trapped at temperatures below 50 °C. Type II inclusions were associated with late magmatic-hydrothermal fluids, while type I inclusions indicate dilution and interaction of the ore-forming fluid with meteoric water. The pegmatites are characterized by aqueous LV inclusions indicative of magmatic to meteoric origin. [ABSTRACT FROM AUTHOR]

Although China is well-endowed with tungsten deposits, while the tungsten resources in the Central Asian Orogen Belt (CAOB) are rarely reported. Recently, many W-skarn deposits have been discovered in the East Tianshan, but the source and evolution of the mineralising fluids are poorly understood. The Xiaobaishitou W(–Mo) deposits are hosted by carbonaceous limestone or banded crystalline limestone in the Mesoproterozoic Jianshanzi Formation, which is intruded by Triassic biotite monzogranite. The deposit comprises garnet-dominated prograde skarn and retrograde skarns followed by oxides (scheelite–cassiterite–magnetite), sulphides (quartz–molybdenite–bismuthinite–pyrite–chalcopyrite–sphalerite–galena), and carbonate stages. The types of fluid inclusions are composed of liquid-rich aqueous, vapour-rich aqueous, aqueous carbon-dioxide, and daughter mineral-bearing inclusions. The homogenization temperatures of fluid inclusions change from > 400 °C in garnet, through > 380 °C in epidote and 310–280 °C in scheelite, to 280 °C in quartz and 220 °C in calcite indicating a complex magmatic-hydrothermal process. The δ18Owater values varied from + 6.1 to + 8.4‰ in garnet, + 5.2 to + 7.4‰ in epidote, + 2.0 to + 3.0‰ in quartz, to − 0.7 to − 0.1‰ in calcite. The corresponding δD values are − 95 to − 71‰ in garnet, − 84 to − 80‰ in epidote, − 115 to − 90‰ in quartz and − 101 to − 89‰ in calcite. Both O and H isotopic compositions show the mineralisation fluids are originated from deep-sourced magmatic fluids. The δ13CCO2 values in the calcite range from − 7.8 to − 7.7‰, which is characteristic of magmatic fluids interacting with reduced carbon from metamorphic rocks. The δ34S values of hydrothermal fluids range from + 4.5 to + 5.1‰, and 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of sulphide are 18.072–18.664, 15.566–15.708, and 38.245–38.658, respectively, representing a mixed characteristic of magmatic and sedimentary sulphur. Considering the coexisting of L-type and V-type inclusions in the scheelite, we proposed that pH increase caused by fluid boiling may be the major cause for the precipitation of scheelite at the Xiaobaishitou deposit. [ABSTRACT FROM AUTHOR]

The Dongji epithermal Au deposit formed in the Early Cretaceous is located in the Dongkeng volcanic Basin of the South China Block. The orebodies of the deposit are mainly hosted in the Jurassic volcanic–subvolcanic rocks. Here, detailed zircon U–Pb geochronology, major‐trace elements, and fluid inclusion data of the Dongji deposit are reported. At least two epochs of magmatic activity were identified at Dongji, including the Late Jurassic rhyolitic crystal tuff lava (165.3 ± 1.8 Ma to 162.8 ± 2.6 Ma) and quartz porphyry (156.0 ± 1.9 Ma), and the Early Cretaceous dacitic crystal tuff lava (108.4 ± 5.7 Ma) and purplish‐red crystal tuff lava (98.1 ± 0.8 Ma). The Late Jurassic volcanic–subvolcanic rocks are characterized by high SiO2 content, enriched LILE (large ion lithophile element) elements, depleted HFSE (high field strength element) elements, and obvious P, Ti and Eu anomalies. These geochemical characteristics suggest that the volcanic–subvolcanic rocks were generated by partial melting of the lower crust and controlled by fractional crystallization of Ti‐bearing phases, apatite, and plagioclase. In comparison, the Early Cretaceous volcanic–subvolcanic rocks are characterized by high K contents, and arc‐like signatures (e.g., enriched Rb, Th, K, and depleted Nb, Ta, Ti), indicating a partial melting of crust–mantle interaction under an extensional tectonic setting. The ore‐bearing dacitic crystal tuff lava and the caprock of purplish‐red tuff lava constrain the timing of gold mineralization in the range of 108–98 Ma. The Au mineralization at Dongji is divided into the early stage of quartz‐pyrite association and the late main mineralization stage of quartz‐polymetallic sulfide association. The fluid inclusion microthermometry results show that the ore‐forming fluids at the early mineralization are characterized by enrichment of liquid‐rich two‐phase inclusions and CO2‐bearing aqueous inclusions. The fluids with moderate homogenization temperatures (292–382°C) and low salinities (5.4–10.0 wt% NaClequiv) were possibly exsolved from magmatic rocks. Nevertheless, fluid inclusions in the late‐stage contain liquid‐rich two‐phase inclusions and pure liquid phase inclusions. The homogenization temperatures (222–309°C) and salinities (2.4–8.3 wt% NaClequiv) of the late‐stage fluid inclusions are relatively lower than those of the early stage, probably indicating a fluid mixing of magmatic and meteoric fluids. Based on the above, we propose that fluid mixing is the key factor facilitating Au precipitation in the Dongji deposit, probably applicable to other Au deposits in the Dongkeng volcanic Basin. [ABSTRACT FROM AUTHOR]