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The Daocaowan antimony (Sb) deposit is a newly discovered Sb deposit located outside the northeast Xikuangshan ore field. In the absence of geochemical data, the metallogenic mechanism of the Daocaowan Sb deposit and its relationship with the Xikuangshan ore field remains unclear. Using high-resolution LA-ICP-MS technique, this study quantitatively determined the in-situ S isotope values and trace element composition of stibnite from the Daocaowan Sb deposit in South China to investigate the source of ore-forming materials and genesis of this deposit. The trace element compositions of stibnite from the Daocaowan Sb deposit revealed the form of occurrence and substitution mechanism of trace elements in stibnite, providing new constraints for explaining the genesis of Sb deposits. The relatively smooth LA-ICP-MS profiles indicate that As, Cu, Hg, and Pb primarily occur as solid solutions in stibnite. Therefore, we speculate that the substitution 3Sb3+↔As3+ + 2Cu+ + Hg2+ + Pb2+ may be the reason for the enrichment of As, Cu, Hg, and Pb in stibnite. A comparison with the Xikuangshan Sb deposit reveals the metallogenic mechanism of the Daocaowan Sb deposit, and the relationship between the two. With the exception of higher content of Fe in Stibnite from the Daocaowan deposit as compared to the Xikuangshan deposit, other trace elements are similar between the two deposits. The results show that the Daocaowan and Xikuangshan Sb deposits may have the same source of ore-forming fluids. We propose that the ore-forming fluid flowed through the Xikuangshan Sb deposit along the F75 fault and dissolved pyrite in the wall rock. Subsequently this fluid containing a high concentration of Fe precipitated and mineralized at Daocaowan. Meanwhile, the S isotope value of the Daocaowan Sb deposit (+6.65 to +9.29‰) is consistent with that of the Xikuangshan, proving that the ore-forming materials of the two deposits are from the same source, probably the basement strata. We propose that the Daocaowan Sb deposit is part of the Xikuangshan ore field, indicating a great prospecting potential in the northeast of the Xikuangshan ore field.

The world-renowned Jinchuan Cu-Ni-(PGE) sulfide deposit consists of four mainly independent intrusive units from west to east, namely Segments III, I, II-W, and II-E, and the main sulfide types are the disseminated, net-textured, massive, and Cu-rich ores. Due to the similar geochemical characteristics of each segment, there is no convenient method to distinguish them and explain their respective variations. Meanwhile, considering that the division of different types of ores is confusing and their formation is still controversial, direct classification using elemental discrimination maps can facilitate subsequent mining and research. In this paper, we report the new major and trace elements data from the Jinchuan deposit and collect the published data to construct a database of 10 major elements for 434 samples and 33 trace elements for 370 samples, respectively, and analyze the data based on multivariate statistical analysis for the first time. Robust estimation of compositional data (robCompositions) was applied to investigate censored geochemical data, and the input censored data were transformed using the centered log-ratios (clr) to overcome the closure effect on compositional data. Exploratory data analysis (EDA) was used to characterize the spatial distribution and internal structural features of the data. The transformed data were classified by partial least squares-discriminant analysis (PLS-DA) to identify different compositional features for each segment and ore type. The receiver operator characteristic (ROC) curve was used to verify the model results, which showed that the PLS-DA model we constructed was reliable. The main discriminant elements were obtained by PLS-DA of the major and trace elements, and based on these elements, we propose the plot of SiO2 + Al2O3 vs. CaO + Na2O + K2O and Cs + Ce vs. Th + U to discriminate the different segments of the Jinchuan deposit, and the Al2O3 + CaO vs. Fe2O3T + Na2O and Co + Cu vs. Rb + Th + U to discriminate the different ore types. In addition, we predict that there are still considerable metal reserves at the bottom of Segment I.

The study of enclaves in granitic plutons provides fundamental information on the petrogenesis of their host rocks. Here we combine U–Pb zircon ages, petrography, geochemistry and Nd–Hf isotope composition to investigate the origin of dioritic–granodioritic enclaves and their host granodiorites and biotite granites in the Xuehuading–Panshanchong area, which is a pivotal site to study the Palaeozoic intracontinental orogenic processes of the South China Block. Obtained ages indicate that the host rocks were formed in early Silurian time (c. 432 Ma). The enclaves are fine grained, but with mineral assemblages similar to their hosts and contain amphibole, biotite and plagioclase. All rocks have fractionated rare earth element patterns ((La/Yb)N = 2.86–8.16), except for one biotite granite that has a concave rare earth element pattern ((La/Yb)N = 1.50). Most rocks are depleted in Ta–Nb–Ti, and have negative Eu anomalies and ϵNd(t) (–8.86 to –5.75) and zircon ϵHf(t) (–13.30 to –4.11, except for one, –39.08). We interpret that the enclaves were formed at the borders of magma-ascending conduits, where the mafic mineral crystallization was enhanced by rapid cooling. Conversely, the biotite granites were produced by fractional crystallization from a related granodiorite magma. The sample with a concave rare earth element pattern may have been influenced by hydrothermal fluid–melt interaction. Geochemical modelling suggests that the granodiorites were likely generated by disequilibrium melting of heterogeneous amphibolites in the middle–lower crust. Considering the geological data for the Palaeozoic magmatic rocks in the South China Block, we propose that the Xuehuading–Panshanchong magmatism was likely triggered by piecemeal removal of the thickened lithospheric root and subsequent thermal upwelling of mantle, without a mantle-derived magma contribution to the granites.

The North Qilian orogenic belt in North China has been defined as a subduction–collision zone between the Alxa Block and the Qilian Block. We present petrography, zircon U–Pb geochronology, major- and trace-element geochemistry, and Sr–Nd–Pb–Hf isotope analysis for the Yushigou diabase from the Longshoushan area, which is located SW of the Alxa Block, aiming to understand its petrogenetic link to subduction processes. The Yushigou diabase belongs to the tholeiite series, and shows enrichment in light rare earth and large-ion lithophile elements, and a depletion in heavy rare earth and high-field-strength elements. Laser ablation – inductively coupled plasma – mass spectrometry U–Pb zircon dating yielded an emplacement age of 414 ± 9 Ma, with an ϵHf(t) value in the range of −10.3 to 1.8. The whole-rock initial 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of the diabase range over 16.811–17.157, 15.331–15.422 and 37.768–37.895, respectively. The (87Sr/86Sr)i ratios vary between 0.7086 and 0.7106, and ϵNd(t) values vary between −14.4 and −13.4, which are significantly higher than the ϵHf(t) value (Nd–Hf decoupling). An interpretation of the elemental and isotopic data suggests that the Yushigou diabase was derived from partial melting of an enriched mantle I (EM-I) -type lithospheric mantle in the spinel–garnet transitional zone. Based on the geochemical features and previous regional geological data, we propose that the Silurian magmatism was most likely triggered by slab break-off after the closure of the North Qilian Ocean, and ancient continental materials from the subduction slab metasomatized the overlying lithospheric mantle during exhumation.

Crustal structure and fluid or melt originating in the deep crust and mantle are critical in regional magmatic mineral systems. However, the crustal structure and the processes that entrain and focus fluids from a deep-source region to a metallogenic belt remain relatively undisclosed. We present a magnetotelluric (MT) study of the eastern Qimantagh Metallogenic Belt (QMB) in the northern Tibetan Plateau. Data from 33 MT stations in two sections and 7 dispersed stations are acquired using a surface electromagnetic prospecting (SEP) system in frequency band ranges from 320 Hz to 0.00034 Hz. Data are converted by Bostick conversion and two-dimensional (2D) nonlinear conjugate gradient inversion. Our MT results reveal the geoelectrical crustal structure of the QMB, which consists of a southern low-resistivity domain that reflects the Kumukuri rift, a high-resistivity middle domain that represents the southern QMB in the central Kunlun belt, and a northern low-resistivity domain that covers the northern QMB and southwestern Qaidam block. We present a comprehensive tectonic and geophysical model of QMB based on the MT interpretation and geological analysis. We infer the high-resistivity domain as a reflection of a rigid crust and detached lithospheric mantle, this belt separate the QMB into northern and southern QMB. Most of the mineral deposits are found in the northern low-resistivity domain of QMB. Our study and findings provide an understanding of the tectonic evolution of the northern Tibetan Plateau, the crustal structure that controls the temporal and spatial distribution of magmatic rocks, and the geological signature associated with mineral deposits.

The study of fluid inclusions is important for understanding various geologic processes involving geofluids. However, there are a number of problems that are frequently encountered in the study of fluid inclusions, especially by beginners, and many of these problems are critical for the validity of the fluid inclusion data and their interpretations. This paper discusses some of the most common problems and/or pitfalls, including those related to fluid inclusion petrography, metastability, fluid phase relationships, fluid temperature and pressure calculation and interpretation, bulk fluid inclusion analysis, and data presentation. A total of 16 problems, many of which have been discussed in the literature, are described and analyzed systematically. The causes of the problems, their potential impact on data quality and interpretation, as well as possible remediation or alleviation, are discussed.

Middle-Late Jurassic high Sr/Y granitic intrusions are extensively exposed in the Liaodong Peninsula, in the eastern part of the North China Craton (NCC). However, the genesis of the high Sr/Y signature in these intrusions has not been studied in detail. In this study, we report results of zircon U-Pb dating, Hf isotopic analysis and zircon and whole-rock geochemical data for the Late Jurassic Zhoujiapuzi granite in the middle part of the Liaodong Peninsula. The Zhoujiapuzi granite is high-K (calc-alkaline) and peraluminous in nature, with high SiO2 (68.1–73.0 wt %) and Al2O3 (14.5–16.8 wt %), low in TFe2O3 (1.10–2.49 wt %) and MgO (0.10–0.44 wt %), and with high Sr/Y (19.9–102.0) and LaN/YbN (14.59–80.40). Morphological and chemical studies on zircon grains show that there are two stages of zircon growth, interpreted as magmatic evolution in two distinct stages. The early stage of zircons (ESZ) reflects a crystallization environment of low oxygen fugacity and high TZr-Ti (Ti-in-zircon thermometer values: 669–792 °C); the late stage of zircons (LSZ) formed with high oxygen fugacity and lower TZr-Ti (498–720 °C). LA-ICP-MS U-Pb zircon dating yielded the formation ages of the ESZ and LSZ of ~162 ± 1 Ma and ~158 ± 1 Ma, respectively, with similar εHf(t) values in the range of &minus26.3– −22.8. Interpretation of the elemental and isotopic data suggests that the Zhoujiapuzi granite was a I-type granite derived from partial melting of basement in the region: ~2.17 Ga Liaoji granites. The high Sr/Y signature is most likely inherited from these source rocks. Based on the geochemical features and regional geological data, we propose that the Liaodong Peninsula in the Late Jurassic was part of a mature continental arc, with extensive melting of thick crust above the Paleo-Pacific subduction zone.

The ilvaite-bearing skarn associations in the Galinge skarn deposit were studied to determine their physicochemical formation conditions. A thermodynamic model setting pressure of 50 MPa (Pf=Ps=50 MPa) was set up to trace the skarn evolution. Petrographic evidence for replacement of garnet and magnetite by ilvaite in the early retrograde stage (Stage I) combined with thermodynamic modeling suggests that the alteration may have occurred at 400–470 °C under moderately high fO2 with ΔlgfO2(HM) ranges from −4 to −4.2. The model is based on a maximum pressure of 50 MPa calculated from magmatic amphibole geobarometer. The continuous breakdown of ilvaite with quartz to form ferro-actinolite and magnetite occur in the late retrograde stage (Stage II). The reactions occurred at 400-440°C under moderate fO2 (ΔlgfO2(HM): −4 to −4.4). In Stage III, the breakdown of ilvaite to form calcite, pyrite and ferroactinolite depends on XCO2 which can be estimated to be in a range of 0.005 to 0.05, and the reaction would occur at higher temperatures with increasing XCO2. Under these conditions, the breakdown occurs at 270–350 °C and low fO2 (ΔlgfO2(HM): up to −5.2). The thermodynamic model for continuous evolution from Stage I to Stage III completely records the conditions of the retrograde alteration, which is inconsistent with the thermobarometry imprints of fluid inclusions. Therefore, the petrography and phase relations of ilvaite are useful indicators of reaction conditions in various skarn deposit types.

The gold mineralization in the Longtoushan hydrothermal gold deposit is concentrated within the contact zone of the granitic complex. Whole rock geochemistry and in-situ U-Pb and Hf isotopic data were used to constrain the genesis and age of the granites and related Cu-Au mineralization in the Longtoushan Deposit. The granites mainly consist of the granite porphyry, rhyolite porphyry, porphyritic granite and quartz porphyry. LA-ICP-MS U-Pb dating of zircons from the granite porphyry, rhyolite porphyry and quartz porphyry indicates that they intruded from ca. 94 to 97 Ma. These intrusions exhibit similar trace element characteristics, i.e., right-dipping REE patterns, depletion of Ba, Sr, P and Ti, and enrichment of Th, U, Nd, Zr and Hf. The eHf (t) values of zircons from the granite porphyry, rhyolite porphyry and quartz porphyry range from −26.81 to −8.19, −8.12 to −5.33, and −8.99 to −5.83, respectively, suggesting that they were mainly derived from the partial melting of the Proterozoic crust. The Cu-Au mineralization is mainly related to the rhyolite porphyry and porphyritic granite, respectively. The Longtoushan granites were most likely formed in a post-collisional extensional environment, and the deposit is a part of the Late Yanshanian magmatism related mineralization in the Dayaoshan area and its adjacent areas.

Late Early Oligocene mantle-derived potassium (K)-rich lavas occur widely in the Qiangtang Block, central Tibet. However, it remains ambiguous whether partial melting of crust beneath central Tibet...

The Xikuangshan antimony (Sb) deposit is the world’s largest known Sb deposit. Due to the lack of suitable minerals for reliable high-precision radiometric dating, it remains difficult to determine the exact age of Sb mineralization in this deposit. Here, we report the first LA-MC-ICP-MS U-Pb ages of syn-stibnite calcite from this deposit. The dating results indicate the presence of at least two stages of Sb mineralization in the Xikuangshan ore district. The calcite-stibnite veins in the Daocaowan ore block probably formed during the Paleocene (58.1 ± 0.9 Ma), representing an early stage of Sb mineralization, while the quartz-stibnite vein in the Feishuiyan ore block probably formed during the Eocene (50.4 ± 4.4 Ma, 50.4 ± 5.0 Ma, and 51.9 ± 1.6 Ma), representing a late stage of Sb mineralization. The new calcite U-Pb ages are significantly younger than the calcite Sm-Nd ages (124.1 ± 3.7 Ma, 155.5 ± 1.1 Ma) reported by previous researchers. We suggest that Sb mineralization of the South China antimony metallogenic belt may be related to tectono-thermal events during Paleogene, possibly linked to high heat flow during the subduction (ca. 60–40 Ma) of the Pacific Plate beneath the Eurasian Plate and/or the Indo–Asian Collision (began at ca. 61 Ma). The young in situ U-Pb ages of calcite challenge the idea of late Mesozoic Sb mineralization in the South China antimony metallogenic belt, suggesting the requirement for more high-precision dating studies.

The Kaerqueka polymetallic deposit, Qinghai, China, is one of the typical skarn-type polymetallic ore deposits in the Qimantage metallogenic belt. The dynamic mechanism on the formation of the Kaerqueka polymetallic deposit is always an interesting topic of research. We used the finite difference method to model the mineralizing process of the chalcopyrite in this region with considering the field geological features, mineralogy and geochemistry. In particular, the modern mineralization theory was used to quantitatively estimate the related chemical reactions associated with the chalcopyrite formation in the Kaerqueka polymetallic deposit. The numerical results indicate that the hydrothermal fluid flow is a key controlling factor of mineralization in this area and the temperature gradient is the driving force of pore-fluid flow. The metallogenic temperature of chalcopyrite in the Kaerqueka polymetallic deposit is between 250 and 350 °C. The corresponding computational results have been verified by the field observations. It has been further demonstrated that the simulation results of coupled models in the field of emerging computational geosciences can enhance our understanding of the ore-forming processes in this area.

As the largest low-sulfidation (LS) epithermal deposit in the Tulasu basin, western Tianshan, NW China, the Axi gold deposit has a poorly understood geologic history. It is not clear whether hydrothermal mineralization occurred during a single event or multiple events. In this paper, new data consist of whole rock geochemistry and mass-change calculations for hydrothermal alteration. LA-ICP-MS trace element analysis of pyrite was conducted in order to develop a comprehensive metallogenic model. The pyrite-sericite-quartz alteration at the Axi deposit is characterized by replacement of plagioclase and mafic phenocrysts by sericite, quartz, pyrite (py1), smectite, and illite, indicating slightly acidic and reducing conditions during the early ore stage. Medium subhedral pyrite crystals (py1) with porous texture are typically sited adjacent to iron-rich minerals (e.g., hornblende) and are characterized by Co-Ni-Mn enrichment with high ratios of Co/Ni (avg. 1.114) and Cu/As (avg. 0.655), implying preferential sulfidation reactions in magmatic hydrothermal systems. The quartz ± calcite ± pyrite ± adularia assemblages in silicified rocks and the strong mobility of LREE both reflect a slightly acidic chloride-rich solution phase during the later ore stage. Coarse anhedral pyrites with cataclastic texture (py2) and medium euhedral pyrites (py3) have a mixed hydrothermal origin and were deposited with quartz during Au-pyrite-quartz and Au-polysulfide-quartz stages, respectively. Py2 and py3 both have significantly lower Cu/As ratios (avg. 0.103 and avg. 0.088, respectively) than py1, indicating the input of meteoric fluid during the later ore stage. The three generations of pyrite, especially py3, have significant lattice-bound gold contents (py1: 0.01–38.86 ppm, median 1.51 ppm; py2: 0.03–234.37 ppm, median 1.21 ppm; py3: 3.31–231.56 ppm, median 42.72 ppm). Gold precipitation is associated with the destabilization of Au-bearing chlorine (Au(Cl)2−) and bisulfide complexes (Au(HS)2−) via sulfidation and fluid boiling. All of these characteristics indicate the Axi epithermal deposit is the result of two stages of mineralization.

Intracontinental orogens are major sites to better understand tectonic regime of plate interior. However, deep response to those processes remains poorly constrained due to the rare exposure of mag...

The Longtoushan hydrothermal gold deposit is located in the southwestern region of the Dayaoshan Uplift. Tourmaline is widespread in the Longtoushan gold deposit and is mainly distributed in the rhyolite porphyry and associated cryptoexplosive breccia. The spatial distribution of tourmaline enrichment is similar to that of the gold orebody. Feldspar has been largely replaced by tourmaline in the rhyolite porphyry and cryptoexplosive breccia. Electron microprobe analysis revealed that tourmalines in the Longtoushan deposit belong mainly to the alkali group and partly to the X-vacant group; they mostly fell in the schorl-dravite series field. Two distinct sets of dominant substitutions were observed: MgFe−1 and Al□(NaR2+)−1, where R = Fe, Mg. In addition, minor substitutions include (CaMg)(NaAl)−1 and FeAl−1. The calculated δ11B value for the mineralizing fluids ranged from − 12.8 to − 9.7‰, which is typical of S-type granites, and boron-enriched fluids predominantly derived from rhyolitic melt. Part of the tourmaline from the rhyolite porphyry crystallized during the magmatic-hydrothermal stage, whereas most tourmalines from the deposit formed in the post-magmatic hydrothermal stage. The tourmalines were deposited from a relatively reduced and acidic fluid system, and the gold predominantly precipitated during the post-magmatic hydrothermal stage in the Longtoushan deposit.

In extended-reach and directional drilling, cuttings transport is a key issue associated with the efficiency of hole-cleaning and drilling operation. If the cuttings cannot be returned to the surface in time, many technical difficulties may arise such as excessive torque and drag, stuck pipe, and loss of well control. In this study, a computational fluid dynamics (CFD) approach with Eulerian–Eulerian (EE) multiphase model was employed to comprehensively understand and analyze the effect of several drilling operation parameters, mud rheological properties, and specularity coefficient (representing various wellbore wall conditions) on the cuttings transport performance. A commercial CFD software (ANSYS FLUENT™ 19.1) was used to implement all simulations, and a sensitivity analysis was executed with an error of less than 5%. Furthermore, the motion patterns of cuttings were observed and analyzed under various factors. The results show that the cuttings transport performance is sensitive to the wellbore wall condition. In the lower side of annuli, the volume fraction of cuttings increases significantly by 28% with increasing specularity coefficients. Additionally, the combined influence of critical shear rate and flow rate on the cuttings distribution was investigated. The relative reduction rate of cuttings concentration decreased by 30% with increasing critical shear rate at the fluid velocity of 0.4 m/s, while that didn't change so obviously at the fluid velocity of 0.8 m/s.

The Hutouya Pb-Zn deposit located in Qinghai, China, is a typical skarn-type polymetallic deposit in the Qimantage metallogenic belt. This belt is characterized by extensive magmatic activity, complicated ore-forming element assemblages and various carbonate-bearing strata. Considering the geological features, mineralogy and geochemistry in the field, we have conducted finite difference simulations of the mineralizing process of galena and sphalerite in terms of a temperature-gradient driven flow. Specifically, we have used modern mineralization theory to quantitatively estimate the duration of the mineralizing process of galena and sphalerite in the Hutouya Pb-Zn deposit. The associated computational simulation results have demonstrated that the hydrothermal fluid flow is a key controlling factor of mineralization in this area. The mineralization of galena and sphalerite corresponds to the quartz sulfide stage, whereas the ore-forming time of galena is later than that of sphalerite. The best metallogenic temperatures of the galena and sphalerite are 150 °C and 250 °C, respectively. These computational results can enhance our understanding of the ore-forming processes in the Hutouya Pb-Zn district.

The Yejiwei deposit, which is located in the southern Hunan W–Sn–Pb–Zn Metallogenic Belt in south China, is a large-scale porphyry–skarn–veinlet-type deposit containing 806 t In. Mineralization occurs as porphyry-type Sn (stockworks), skarn-type Sn–Cu, marble-hosted-type Sn–Cu (veinlet), and vein-type Pb–Zn ores. Thirty-five ore samples were collected from the Yejiwei deposit for bulk and mineral chemical composition, microscopic observation and electron microprobe analyses. The porphyry-type Sn ores contain variable amounts of In (2.3–76 ppm; mean of 17.4 ppm) with local In enrichment (226 ppm) and 1000 × In/Zn values are 3.8–52.4. The skarn-type Cu–Sn ore is richest in In (12.3–214 ppm; mean of 114 ppm), and 1000 × In/Zn values are 2.4–117. In contrast, the In content of the marble-hosted-type Cu–Sn ores is relatively low (7.4–34.9 ppm; mean of 20.3 ppm), and 1000 × In/Zn is in the range of 0.61–5.5, and the vein-type Pb–Zn ores in the external zone contain the lowest In contents (7.2–17.0 ppm; mean of 12.1 ppm) with 1000 × In/Zn values of 0.07–0.09. The ore minerals in the deposit include pyrite, pyrrhotite, cassiterite, and In-bearing minerals of sphalerite, chalcopyrite, and stannite. Although only trace amounts of sphalerite are hosted in the porphyry ores, the sphalerite contains the highest In content (0.27–10.1 wt.% In) in the deposit. We observed the highest In contents of all In-bearing sphalerite reported in China. The In contents of sphalerite in the skarn-type ore range from 0.15 to 0.56 wt.%, whereas the marble-hosted-, and vein-type ores have lower In contents (0.00–0.04, and 0.03–0.06 wt.%, respectively). The In resources of the Yejiwei deposit are mainly hosted in skarn ores of the No. 31 and No. 32 orebodies. The genesis of In in the Yejiwei deposit was closely related to the shallow intrusive environment of related igneous rocks. As W–Sn–Mo–Bi–Cu–Pb–Zn–Ag mineralization is widespread in south Hunan, this study would suggest a focus on skarn-type Sn–Zn deposits for the future prospecting of In resources.

We report petrological, cathodoluminescence (CL), major and trace element analyses and fluid inclusion studies on scheelite (W)-mineralized granodiorite porphyries from Dongyuan and Zhuxiling, southern Anhui Province (China). In Dongyuan, the larger part of the granodiorite porphyry body is mineralized with W concentrations up to 1140 g/t (total WO3 reserves >140 000 tonnes), whereas in Zhuxiling mineralization is spatially more limited. All mineralized rocks are strongly altered, containing abundant calcite and no fresh plagioclase. W-mineralized rocks show higher K, Pb and lower Na, Sr, Ti contents compared to the non-mineralized ones. Co-variations between mobile elements (K, Na, Pb, Sr, Rb, etc.) and W, combined with petrological observations, demonstrate that fluid alteration must have controlled the mineralization. In quartz from both deposits 4 types of fluid inclusions have been recognized, i.e., aqueous-carbonic (WC-type), aqueous (W-type, subdivided into Wm-type containing minor detected CO2 and Wn containing no CO2), carbonic (pure CO2, C-type) and late secondary aqueous inclusions (LW-type). WC- and LW-type inclusions represent the original magmatic fluids and meteoric waters, respectively. The other inclusions represent evolved magmatic fluids which are closely related to alteration and mineralization. WC-, Wm- and Wn-type inclusions show higher salinity and lower homogenization temperatures, indicating fluid immiscibility with CO2 effervescence. Additionally, during plagioclase alteration and precipitation of K-feldspar and sericite the K/Na ratio is lowered and Ca released. The precipitation of scheelite must have been promoted by increasing Ca contents in the fluid and also by increasing pH due to CO2 loss. The present study demonstrates that for granitic rocks without calcareous wall rock, plagioclase breakdown must have been the key factor for scheelite mineralization. The presence of CO2-rich fluid indicates that both deposits formed in the same intracontinental extension setting as those in the Nanling region. Thus, the Yanshanian granites from southern Anhui Province may have a great potential for W mineralization, especially the blind ones in deep levels.

The association between mineralization and hydrocarbons in sedimentary basins is widely recognized, but the nature and significance of their relationships are not fully understood. This paper provides an example of metalliferous brines injecting into a palaeo-oil–gas reservoir to form a world-class Zn–Pb deposit (Jinding, China). Petrographic and microthermometric studies of oil inclusions and PVT simulations suggest that oil and gas were charged in a shallow (

The Jingchong Co–Cu polymetallic deposit and a few other Co (–polymetallic) ore deposits are located in northeastern Hunan Province, in the central segment of the Jiangnan Orogen, South China. These deposits occur along the NE-trending Changping (Changsha–Pingjiang) deep fault zone and show a spatial association with the Late Jurassic–Early Cretaceous Lianyunshan granitoids, which intruded the Archean to Paleoproterozoic Lianyunshan Group comprising metaclastic-sedimentary rocks interlayered with mafic-intermediate igneous rocks. The Jingchong deposit is hosted within an altered fracture zone at the footwall of the Changping fault zone, and comprises an upper Pb–Zn ore zone and a lower Co–Cu ore zone. Wall rock alteration is dominated by silicification and chloritic alteration. Three types of ores were identified, i.e., quartz–sulfide veins, altered structural breccias and altered fractured rocks. Integrated field work and microscopy observations reveal a three-stage hydrothermal process related to mineralization: 1) quartz + chlorite (ChlI) + pyrite, 2) quartz + chlorite (ChlII) + pyrite + chalcopyrite + cobaltite, and 3) quartz + carbonate + galena + sphalerite ± pyrite ± chalcopyrite. LA-ICPMS analyses reveal that the Co contents are 1315–6473 ppm, 76–3866 ppm, and 5–435 ppm for pyrite from the first-, the second-, and the third stages, respectively. EPMA analyses of chlorite show that ChlI and ChlII have Fe/(Fe + Mg) ratios of 0.65–0.80 and 0.76–0.92, and AlIV contents of 1.30–1.65 apfu (atom per formula unit) and 1.18–1.48 apfu, respectively. Empirical geothermometry of chlorite yielded temperatures of 256–318 °C (av. 281 °C) and 239–290 °C (av. 256 °C) for first- and second-stage chlorite, respectively. The δ34SVCDT values of sulfides (−4.9‰ to 0.2‰, av. −1.6‰) suggest a magmatic source for the sulfur, and the 3He/4He (0.017–0.30 Ra) and 40Ar/36Ar (285–306) ratios of fluid inclusions in pyrite suggest that the ore-forming fluids were mainly crust-derived magmatic hydrothermal fluids with possible meteoric water inputs. The 206Pb/204Pb (18.042–18.746), 207Pb/204Pb (15.592–15.741) and 208Pb/204Pb (38.237–39.150) ratios of ore sulfides are similar to those of the Lianyunshan Group, suggesting that the metals may have been derived from the latter. Integrating the geological, mineralogical and geochemical data documented in this study, we propose that the Jingchong Co–Cu polymetallic deposit formed from a hydrothermal system related to the Lianyunshan pluton, which was derived from crustal anataxis of the Lianyunshan Group in a back-arc extensional setting in the Late Mesozoic.

The Dabie Orogen is a world-class case for large amounts of Mo mineralization in that it contains at least 10 porphyry Mo deposits with Mo metal reserves over 3 Mt from the time period of 156–110 Ma. However, the principal mechanism for the Mo mineralization remains controversial due to the lack of a precise definition of its source and shallow ore-forming process, which is essential to understand these rare large Mo deposits. Detailed geochronology, geochemistry, and isotopic data for ore-related granites and minerals were analyzed in order to place constraints on the massive Mo mineralization in the Dabie Orogen in eastern China. The Yaochong molybdenum orebodies were hosted in the transition belt and alteration zone between the granitic stocks and the Dabie Complex and were characterized as numerous veinlets with potassic, phyllic and propylitic alterations. The buried Yaochong granitic intrusions and associated molybdenum mineralization yield Early Cretaceous ages of magmatic activities at ca. 138 Ma and extremely similar Re–Os isotope ages for the corresponding Mo metallogenic event at ca. 137 Ma. The Yaochong monzogranite and granite porphyry belong to the highly fractionated I-type granites, which are believed to be derived from the dominantly Yangtze's lower crust mixed with the Northern Dabie Complex due to their geochemical and isotope features. The elemental diversity and isotopic homogeneity suggest that the formation of the Yaochong monzogranite involved the fractionation of biotite, garnet and minor feldspar and accessory minerals combined with a weak crustal assimilation process. In contrast, the granite porphyry was possibly generated by the partial melting of the same mixed lower continental crust via the differentiation process involving the fractionation of feldspar, apatite, and/or titanite. Fractional crystallization processes can significantly elevate the molybdenum concentration in the residual melts. The biotite fractional crystallization results in removal of molybdenum from the vestigial magma since molybdenum is compatible with it, which may account for the barren monzogranite with a low-grade molybdenum mineralization. The ore-bearing granite porphyry has more source materials from the Yangtze's lower crust, which may have contributed most of the molybdenum for the porphyry-related molybdenum deposits in the Dabie metallogenic zone. This porphyry molybdenum aggregation may have been deposited in a post-collision or intracontinental extensional setting.

The Gutian porphyry Cu–Mo deposit is a newly proved porphyry copper deposit in the coastal South China associated with granodioritic porphyries. In this study, zircon U–Pb ages and Hf isotope data, as well as geochemical and Sr–Nd–Pb–Re–Os isotopic compositions, are reported for these intrusions and minerals. Both zircon U–Pb and molybdenite Re–Os dating suggest that the Gutian granodiorite porphyries and related mineralization formed at ~ 160 Ma. The Gutian granodiorites show a low-Mg adakitic geochemical affinity, with relatively high K 2 O but low Cr and Ni contents. These rocks have initial ( 87 Sr/ 86 Sr) i ratios of 0.7085 to 0.7097, negative e Nd (t) values (− 12.5 to − 7.8), ( 206 Pb/ 204 Pb) t ratios of 18.048 to 18.241, ( 207 Pb/ 204 Pb) t ratios of 15.609 to 15.628, and ( 208 Pb/ 204 Pb) t ratios of 38.494 to 38.667. Zircons from the granodiorites have negative e Hf (t) values of − 15.7 to − 8.5, which are close to those of Cathaysia crust-derived melts. Geochemical and Sr–Nd–Pb–Hf isotopic compositions suggest that they may be derived from Late Jurassic thickened juvenile lower crust. These lower crustal magma sources may not only contain pre-Proterozoic basement rocks, but also involve Triassic and Middle–Late Jurassic arc magmas within the lower crust, which were likely derived from an enriched mantle source associated with paleo-Pacific Plate subduction from the Middle to Late Jurassic. The Gutian ore-related granodiorites represent a new example for significant contributions of ancient subduction melts and enriched mantle-derived sources for porphyry-type magmatism and Cu-Mo mineralization, which occurred in response to an arc regime during the Middle to Late Jurassic in South China.

The Saishitang–Rilonggou Ore Field (SROF), which includes the Saishitang, Tongyugou, and Rilonggou ore deposits as well as other scattered occurrences, is located in the Elashan region in Qinghai Province, and is a significant Cu–Sn ore field in NW China. These ores are hosted in stratiform skarn deposits with the main metals being Cu and Sn, as well as Zn, Pb, Au, Ag, and trace elements (e.g. Ga, Ge, Se, and In). Bulk-rock geochemical analyses of 50 ore samples from the three deposits show that In contents in the Saishitang deposit range from 0.03 to 39 ppm (average 12.7 ppm, n = 19), with 1000 In/Zn values that vary from >0.01 to 29.83 (average 4.29). Indium contents in the Tongyugou deposit vary from 7.51 to 131 ppm (average 28.37 ppm, n = 13), with 1000 In/Zn values from 0.74 to 48 (average 17.55). Finally, indium contents in the Rilonggou deposit vary from 0.73 to 120 ppm (average 36.15 ppm, n = 18), with 1000 In/Zn values from 0.33 to 47 (average 8.52). Indium is hosted mainly in sphalerite, while some other In-bearing minerals (e.g., roquesite, stannoidite, and stannite) are present locally within the ore field. Roquesite, which replace or fill bornite, occurs in bornite-rich ores in the Saishitang deposit. This is the first reported Chinese locality of roquesite. Based on previously reported Zn resources, a total of 136 tons of In is calculated to be hosted in the SROF, with 30, 66, and 40 tons of In attributed to the Saishitang, Tongyugou, and Rilonggou deposits, respectively. The differences in indium contents among the deposits and their respective geological histories and characteristics suggest that the origin of indium relates to volcanogenic metallogenesis in an early Permian volcano-sedimentary basin. Based on the evaluation of In resources, future mining operations should include the recovery of indium in the Tongyugou and Rilonggou deposits.

Granitoids are widely distributed in Jinchuan at the southwestern margin of the North China plate, which is also an important area of mineral deposits. The research subject of this article are two Paleozoic granitoids, a cataclastic syenogranite and a granodiorite porphyry. This study presents whole rock geochemistry and zircon U–Pb–Hf isotope data for the two granitoids to determine their petrogenesis, source characteristics and tectonic significance. The cataclastic syenogranite is characterized by metaluminous composition with high potassium, and La N /Yb N from 39 to 48. The composition with strong negative Eu anomalies and Zircon saturation temperatures ( T Zr ) from 947 to 1072 °C classify this intrusion as an A-type granite. The granodiorite porphyry is metaluminous with high sodium, sub-alkaline, La N /Yb N ratios from 27 to 32. These I-type intrusions have no Eu anomalies and T Zr ranges from 818 to 845 °C. Both the cataclastic syenogranite and granodiorite porphyry show enrichment of LREE and LILE and depletion of HREE and HFSE, except Hf and Zr. Using single zircon LA-ICP-MS U–Pb dating, the emplacement age of the cataclastic syenogranite and granodiorite porphyry are determined at 433.4 ± 3.7 Ma and 361.7 ± 4.6 Ma, respectively. Zircons from the cataclastic syenogranits have uniform negative e Hf ( t ) values (−11 ± 0.5 to −9 ± 0.5), implying the involvement of an old Palaeoproterozoic crustal source in magma genesis. The zircons from the granodiorite porphyry have e Hf ( t ) values that range from −8 ± 1.0 to +10 ± 0.6, suggesting heterogeneous source materials involving both juvenile and ancient crust reworked crustal components. Based on the geological significance of granites at the southwestern margin of the North China plate, the closure of the North Qilian Ocean occurred at ∼444 Ma. Geochemical features suggest that the cataclastic syenogranite and granodiorite porphyry formed in an intraplate extensional and compressional setting, respectively. Hence after a period of extensional post-collisional intraplate evolution, strong compressive forces affected the area.

Coexisting porphyry Cu-Au and low- to intermediate-sulfidation epithermal Au-Ag mineral systems are well developed in the Oligocene–Miocene volcanic and porphyry rocks in the Cangrejos–Zaruma district, Ecuador, northern Andes. The Humedo deposit, with a defined gold resource of 8 t @ 5 g/t, is a recently discovered Miocene porphyry–epithermal gold deposit in the southwest Cangrejos–Zaruma district. Here the textures, geochemistry, and B isotopes of tourmaline are investigated to understand the fluid evolution of the Humedo gold deposit. Four types of tourmaline (TurA–D) associated with three hydrothermal stages have been identified at Humedo: TurA in the matrix of stage II magmatic hydrothermal breccias, TurB in pervasive phyllic altered and silicified rocks of stage III, and TurC and TurD aggregates hosted in the extensively silicified rock and/or hydrothermal breccias of stage IV. All Humedo tourmaline belongs to the alkali group, with schorlitic–dravitic compositions. The TurA is characterized by the highest Fe, Nb, W, and Sn contents, the heaviest B isotopes (δ11B = 1.4–5.6 ‰), isovalent Al–Fe substitution, and low Eu/Eu* values, suggesting that oxidized magmatic fluids dominated during stage II. The TurB grains hosted by metamorphic and intrusive host rocks have different contents of Sc, Zn, V, and Ni, indicating a local impact on compositions from the host rocks. The low values of δ11B (−9.7 to −2.2 ‰), the correlation of δ11B with Co, and the Fe–Mg substitution of TurB suggest that fluids of stage III were reducing and possibly influenced by interaction with graphite-bearing meta ultramafic–mafic rocks of the Raspas Formation and/or Palenque Unit. The TurC–D is marked by the highest Mg contents of all groups, combined with the positive correlations of δ11B with Mg and Ba, suggesting the existence of external waters that interacted with shallow metasedimentary or volcanic sedimentary rocks during stage IV. The geochemistry and isotope characteristics of tourmaline thus record changes in the ore-forming fluid compositions (magmatic vs. external) and nature (oxidized vs. reduced) caused by fluid-rock interaction with regional country rocks in the Humedo porphyry–epithermal system.

The Huxingshan tungsten deposit (~0.21 Mt at 0.3 wt% WO3) is located in the Jiangnan Massif tungsten ore belt, South China. Here, the W mineralization is restricted to quartz and muscovite-quartz veins intruding variable country rocks of the Lower Cambrian strata. Rb-Sr isochron ages derived from fluid inclusions trapped in muscovite-quartz veins (ca. 134 ± 2 Ma) agree with the zircon U–Pb crystallization age of the associated Huxingshan granite (137.8 ± 0.5 Ma) and may thus suggest a close petrogenetic relationship between both rock types. Zircon eHf (t) values of the Huxingshan granite (−16.2 to +6.6) overlap with those of the specially related metasedimentary Banxi and Lengjiaxi Groups, consistent with melting of Neoproterozoic Yangtze lower crustal materials with mantle melts input to the source. We suggest that the highly differentiated signatures of tungsten and beryllium granite might be inherited from the origin chemistry of source rocks and further modified by highly fractional crystallization rather than by fluid-rock interaction processes. During this process, tungsten and beryllium was enriched in the residual melts/fluids, which finally separated from the solidifying melt body and were introduced into the county rock to precipitate scheelite and beryl along skarn and greisen horizons by large-scale fluid movements. The outlined processes are likely to be coupled to large-scale melting of continental crust and associated granitic magmatism under a regime of subduction of the paleo-Pacific Plate beneath South China and subsequent tearing of the slab. The newly discovered Huxingshan deposit underlines the huge prospecting potential for the northwestern Jiangnan Massif.

The Alxa block is located in the southwestern margin of the North China Craton. The Paleoproterozoic tectonic evolution, crustal growth and tectonic affinity of the block remain unknown or controversial. The Longshoushan (LS) area is one of the few areas that outcrop Paleoproterozoic to crystalline basement rocks in the Alxa Block. In this study, we preset whole-rock geochemistry, zircon U–Pb geochronology and Lu–Hf isotope data from metagabbro, metadiorite, quartz syenite, granitic leucosome and pegmatoid leucosome in the LS area. These rocks all are enriched in LREE and LILE, and depleted in HREE and HFSE. Eight new LA-ICP-MS zircon U–Pb ages yielded three magmatic ages of 2044 Ma, 2029 Ma and 1940 Ma, and three metamorphic ages of 1891 Ma, 1848 Ma and 1812 Ma. Lu–Hf analyses reveal that the magmatic zircons and anatectic/metamorphic zircons from all the rock types are characterized by positive εHf(t) (−0.16 to 10.89) and variable εHf(t) (−11.21 to 6.24), respectively. Based on the previous studies and our new data, we conclude that the LS area experienced three magmatic events (2.5–2.45 Ga, ~2.1–2.0 Ga and ~1.95–1.91 Ga) and three regional metamorphism/anataxis events (~1.93–1.89 Ga, ~1.86–1.84 Ga and ~1.81 Ga) in Paleoproterozoic. The age–Hf isotope data establishes two main crustal growth events at ~2.9–2.5 Ga and ~2.2–2.0 Ga in the LS area. These data indicate that the LS area experienced intraplate extensional setting in the middle Paleoproterozoic, and continental subduction, collision and exhumation in the late Paleoproterozoic. Combining the geochronological framework and tectonic evolution, we suggest that the Alxa Block is part of the Khondalite Belt.

The Annage gold deposit is located at the east part of the eastern Kunlun orogenic belt. The characteristics of ore-forming fluids and metallogenesis were discussed by using fluid petrography, micro-thermometry and hydrogen-oxygen isotope analysis. Three stages, namely quartz-pyrite stage (A), quartz-polymetallic-sulfide stage (B) and quartz-ankerite stage (C) were included in the hydrothermal process as indicated by the results of this study. Inclusions developed in ore-bearing quartz veins from stages A and B are of three types: aqueous inclusions (type I), CO2-bearing inclusions (type II) and pure CO2 inclusions (type III). All three types of inclusions, mainly type I, are presented in stage A, having homogenization temperatures at 180°C - 360°C, and salinities ranging from 0.53% to 21.44%. In addition to development of type I inclusions, type II and III inclusions increase significantly in stage B, with homogenization temperatures ranging from 160°C to 330°C, and salinities are from 1.32% to 22.01%. Based on micro-thermometry, fluids in Annage deposit are of H2O-NaCl-CO2 type with medium-high temperature (140°C - 395°C) and medium-low salinity (0.53% - 22.01%). Results of hydrogen-oxygen isotope analysis show that ore-forming fluid is mainly CO2-rich magmatic fluid, mixed with shallow groundwater or metamorphic hydrothermal in the late mineralization stages. Calculated metallogenic pressures are in the range of 79 - 130MPa corresponding to a maximum depth of 4.8 km. The Annage deposit is a mesothermal quartz vein type gold deposit.

The Ulu Sokor gold deposit is one of the most famous and largest gold deposits in Malaysia and is located in the Central Gold Belt. This deposit consists of three major orebodies that are related to NS- and NE-striking fractures within fault zones in Permian-Triassic meta-sedimentary and volcanic rocks of the East Malaya Block. The faulting events represent different episodes that are related to each orebody and are correlated well with the mineralogy and paragenesis. The gold mineralization consists of quartz-dominant vein systems with sulfides and carbonates. The hydrothermal alteration and mineralization occurred during three stages that were characterized by (I) silicification and brecciation; (II) carbonatization, sericitization, and chloritization; and (III) quartz–carbonate veins. Fluid inclusions in the hydrothermal quartz and calcite of the three stages were studied. The primary CO2–CH4–H2O–NaCl fluid inclusions in stage I are mostly related to gold mineralization and display homogenization temperatures of 269–389 °C, salinities of 2.77–11.89 wt.% NaCl equivalent, variable CO2 contents (typically 5–29 mol%), and up to 15 mol% CH4. In stage II, gold was deposited at 235–398 °C from a CO2 ± CH4–H2O–NaCl fluid with a salinity of 0.83–9.28 wt.% NaCl equivalent, variable CO2 contents (typically 5–63 mol%), and up to 4 mol% CH4. The δ18OH2O and δD values of the ore-forming fluids from the stage II quartz veins are 4.5 to 4.8‰ and − 44 to − 42‰, respectively, and indicate a metamorphic–hydrothermal origin. Oxygen fugacities calculated for the entire range of T-P-XCO2 conditions yielded log fO2 values between − 28.95 and − 36.73 for stage I and between − 28.32 and − 39.18 for stage II. These values indicate reduced conditions for these fluids, which are consistent with the mineral paragenesis, fluid inclusion compositions, and isotope values. The presence of daughter mineral-bearing aqueous inclusions is interpreted to be a magmatic signature of stage IIIa. Combined with the oxygen and hydrogen isotopic compositions (δ18OH2O = 6.8 to 11.9‰, δD = − 77 to − 62‰), these inclusions indicate that the initial fluid was likely derived from a magmatic source. In stage IIIb, the gold was deposited at 263° to 347 °C from a CO2–CH4–H2O–NaCl fluid with a salinity of 5.33 to 11.05 wt.% NaCl equivalent, variable CO2 contents (typically 9–15 mol%), and little CH4. The oxygen and hydrogen isotopic compositions of this fluid (δ18OH2O = 8.1 to 8.8‰, δD = − 44 to − 32‰) indicate that it was mainly derived from a metamorphic–hydrothermal source. The CO2–H2O ± CH4–NaCl fluids that were responsible for gold deposition in the stage IIIc veins had a wide range of temperatures (214–483 °C), salinities of 1.02 to 21.34 wt.% NaCl equivalent, variable CO2 contents (typically 4–53 mol%), and up to 7 mol% CH4. The oxygen and hydrogen isotopic compositions (δ18OH2O = 8.5 to 9.8‰, δD = − 70 to − 58‰) were probably acquired at the site of deposition by mixing of the metamorphic–hydrothermal fluid with deep-seated magmatic water and then evolved by degassing at the site of deposition during mineralization. The log fO2 values from − 28.26 to − 35.51 also indicate reduced conditions for this fluid in stage IIIc. Moreover, this fluid had a near-neutral pH and δ34S values of H2S of − 2.32 to 0.83‰, which may reflect the derivation of sulfur from the subducted oceanic lithospheric materials. The three orebodies represent different gold transportation and precipitation models, and the conditions of ore formation are related to distinct events of hydrothermal alteration and gold mineralization. The gold mineralization of the Ulu Sokor deposit occurred in response to complex and concurrent processes involving fluid immiscibility, fluid–rock reactions, and fluid mixing. However, fluid immiscibility was the most important mechanism for gold deposition and occurred in these orebodies, which have corresponding fluid properties, structural controls, geologic characteristics, tectonic settings, and origins of the ore-forming matter. These characteristics of the Ulu Sokor deposit are consistent with its classification as an orogenic gold deposit, while some of the veins are genetically related to intrusions.

The spatial distribution of ore-forming elements is the result of interaction and influence among multiple factors in the process of mineralization, and is the specific embodiment of non-linearity and coupling of mineralization. The fractal theory has such functions as to characterize non-lineariry and coupling, and can find out the deterministic law from the complicated coupling process. The primary geochemical fractal distribution of metallogenic elements such as Cu and Au possesses the characteristics of multi-fractal distribution in the Dehelongwa copper-gold deposit. Copper follows 2-d fractal distribution, and Au follows 3- or 4-d fractal distribution. The primary geochemical fractal distribution has a certain similarity on the same prospecting line, and this similarity is not obvious among different prospecting lines. The secondary geochemical fractal distribution of Cu and Au is higher in similarity, and simpler than the primary geochemical fractal distribution. These results show that the mineralization of Cu and Au is out of sync and also is inconsistent in this deposit, and the mineralization of Cu mainly experienced two mineralization stages, while the mineralization of Au experienced three to four mineralization stages. Besides the mineralization of Cu and Au shows a certain direction and along the strike of vertical orebodies it is relatively balanced. While along the strike of the ore bodies the mineralization of Cu and Au shows a significant difference. The hypergenic geologic process has a certain effect on the balance of spatial distribution of Cu and Au. From these it can be seen that the mineralization process of this deposit is well characterized by the geochemical fractal distribution of Cu and Au.

The Kendekeke polymetallic deposit, located in the middle part of the magmatic arc belt of Qimantag on the southwestern margin of the Qaidam Basin, is a polygenetic compound deposit in the Qimantag metallogenic belt of Qinghai Province. Multi-periodic ore-forming processes occurred in this deposit, including early-stage iron mineralization and lead-zinc-gold-polymetallic mineralization which was controlled by later hydrothermal process. The characteristics of the ore-forming fluids and mineralization were discussed by using the fluid inclusion petrography, Laser Raman Spectrum and micro-thermometry methods. Three stages, namely, S1-stage (copper-iron-sulfide stage), S2-stage (lead-zinc-sulfide stage) and C-stage (carbonate stage) were included in the hydrothermal process as indicated by the results of this study. The fluid inclusions are in three types: aqueous inclusion (type I), CO2-aqueous inclusion (type II) and pure CO2 inclusion (type III). Type I inclusions were observed in the Si-stage, having homogenization temperature at 240–320°C, and salinities ranging from 19.8% to 25.0% (wt% NaCl equiv.). All three types of inclusions, existing as immiscible inclusion assemblages, were presented in the S2-stage, with the lowest homogenization temperature ranging from 175 °C to 295°C, which represents the metallogenic temperature of the S2-stage. The salinities of these inclusions are in the range of 1.5% to 16%. The fluid inclusions in the C-stage belong to types I, II and III, having homogenization temperatures at 120–210°C, and salinities ranging from 0.9% to 14.5%. These observations indicate that the ore-forming fluids evolved from high-temperature to low-temperature, from high-salinity to low-salinity, from homogenization to immiscible separation. Results of Laser Raman Spectroscopy show that high density of CO2 and CH4 were found as gas compositions in the inclusions. CO2, worked as the pH buffer of ore-forming fluids, together with reduction of organic gases (i.e. CH4, etc), affected the transport and sediment of the minerals. The fluid system alternated between open and close systems, namely, between lithostatic pressure and hydrostatic pressure systems. The calculated metallogenic pressures are in the range of 30 to 87 Mpa corresponding to 3 km mineralization depth. Under the influence of tectonic movements, immiscible separation occurred in the original ore-forming fluids, which were derived from the previous high-salinity, high-temperature magmatic fluids. The separation of CO2 changed the physicochemical properties and composition of the original fluids, and then diluted by mixing with extraneous fluids such as meteoric water and groundwater, and metallogenic materials in the fluids such as lead, zinc and gold were precipitated.

Melt inclusions and fluid inclusions in the Fangcheng basalt were investigated to understand the magma evolution and fluid/melt-peridotite interaction. Primary silicate melt inclusions were trapped in clinopyroxene and orthopyroxene phenocrysts in the Fangcheng basalt. Three types of melt inclusions (silicate, carbonate, and sulfide) coexisting with fluid inclusions occur in clinopyroxene xenocrysts and clinopyroxene in clinopyroxenite xenoliths. In situ laser-ablation ICP-MS analyses of major and trace element compositions on individual melt inclusions suggest that the silicate melt inclusions in clinopyroxene and orthopyroxene phenocrysts were trapped from the same basaltic magma. The decoupling of major and trace elements in the melt inclusions indicates that the magma evolution was controlled by melt crystallization and contamination from entrapped ultramafic xenoliths. Trace element patterns of melt inclusions are similar to those of the average crust of North China Craton and Yangtze Craton, suggesting a considerable crustal contribution to the magma source. Calculated parental melt of the Fangcheng basalt has features of low MgO (5.96 wt%), high Al2O3 (16.81 wt%), Sr (1,670 ppm), Y (>35 ppm), and high Sr/Y (>40), implying that subducted crustal material was involved in the genesis of the Fangcheng basalt. The coexisting fluid and melt inclusions in clinopyroxene xenocrysts and in clinopyroxene of xenoliths record a rare melt-peridotite reaction, that is olivine + carbonatitic melt1 (rich in Ca) = clinopyroxene + melt2 ± CO2. The produced melt2 is enriched in LREE and CO2 and may fertilize the mantle significantly, which we consider to be the cause for the rapid replacement of lithospheric mantle during the Mesozoic in the region.

To study the geochemical anomaly structure of multi-element associations in the South Mining District of the Fenghuangshan Copper Mine, samples were collected and analyzed for their trace element contents. Multi-element anomaly associations were divided according to the correlations between Cu and each of the other elements, and the distribution characteristics of multi-element anomaly associations were also described. Among them, the anomaly distribution of metallogenic element Cu indicates the environment of mineralization. This study provided the basis for research on the metallogenic prediction and geochemistry of the Fenghuangshan Copper Mine.

The Buffalo gold deposit is a small deposit consisting of auriferous quartz-tourmaline veins within a granodiorite stock in the Red Lake greenstone belt. This study aims to characterize the mineralizing fluids through fluid inclusion and stable isotope analyses and to compare them with those of the world-class Campbell-Red Lake deposit. Four types of fluid inclusions were recognized, including carbonic, aqueous-carbonic, aqueous, and halite-bearing aqueous, with the carbonic type being the most abundant. Raman analyses indicate that the carbonic phase mainly consists of CO 2 , with minor amounts of N 2 and CH 4 , and rarely detectable H 2 S. The homogenization temperatures of the carbonic inclusions range from −41.7° to 30.9°C. The homogenization temperatures and salinities of the aqueous, halite-bearing aqueous, and aqueous-carbonic inclusions are 130° to 276°C and 9.7 to 23.6 wt.% NaCl equiv., 155° to 207°C and 32.9 to 42.3 wt.% NaCl equiv., and 215° to 357°C and 8.3 to 19.7 wt.% NaCl equiv., respectively. The δ 18 O VSMOW values of tourmaline range from 8.2‰ to 9.0‰, and those of quartz from 11.4‰ to 11.9‰, with estimated fluid temperatures from 323° to 399°C based on the quartz-tourmaline isotopic geothermometer. It is postulated that separate CO 2 -dominated and aqueous fluids intermittently invaded the fracture/vein system in response to fluid pressure fluctuations, with limited mixing. The CO 2 -dominated fluid, previously recognized in Campbell-Red Lake as the main mineralizing fluid, is inferred to have been derived from deeper parts of the crust. This deep CO 2 -dominated fluid reservoir might have been a common source for gold mineralization in the Red Lake greenstone belt.

The Fenghuangshan Cu-Fe-Au deposit is located in Tongling, Anhui province in central-east China, within the Middle-Lower Yangtze River polymetallic belt. The mineralization is related to Late Yanshanian magmatic intrusions emplaced in Lower Triassic limestones and is divided into two episodes. The first and more important, episode A, is related to granodiorite-granodiorite porphyry and characterized by massive, disseminated, veinlet- and breccia-style mineralization in skarn formed at the contact zone, whereas the second, episode B, is related to a quartz monzodiorite porphyry stock which crosscuts the previous skarn and is characterized by disseminated and veinlet-style mineralization within the porphyry. Based on mineral assemblages and their crosscutting relationships, the hydrothermal evolution of episode A is further divided into five substages (A1–A5), and that of episode B into four (B1–B4), among which A4, A5, and B3 are the main copper mineralization stages. This paper focuses on microthermometric studies of fluid inclusions in the various stages, with an aim to characterize the thermal and compositional evolution of hydrothermal fluids and to discuss their implications for mineralization in terms of fluid sources and metal deposition mechanisms. Fluid inclusions were studied in garnet, quartz, and calcite from stages A1, A4, A5, B1, B2, B3, and B4. Four types and 13 subtypes of fluid inclusions were distinguished based on fluid composition and phase assemblages. Type I fluid inclusions contain one or more salt daughter minerals (halite and sylvite) and homogenize into the liquid phase, whereas type II inclusions homogenize into the vapor phase, both commonly containing an opaque daughter mineral. Type III fluid inclusions are aqueous inclusions that do not contain daughter minerals and homogenize into the liquid phase, and type IV inclusions are CO2 bearing, homogenize to the CO2 or the aqueous phase, and commonly contain an opaque daughter mineral. Primary fluid inclusions in stage A1 are of type I and II, interpreted to represent two immiscible phases resulting from boiling, and those in stages A4 and A5 are of type III. Stages B1 and B2 are characterized by type I primary inclusions, and stages B3 and B4 by type III. Type IV inclusions occur as secondary inclusions in B1 quartz and are interpreted to be related locally to B3 stage mineralization. Microthermometric data indicate a trend of decreasing temperatures and salinities from early to late stages for both mineralization episodes, reflecting a change from a magmatic fluid-dominated system to one invaded by fluids from the country rocks and meteoric water. The fact that the main stages of mineralization (A4, A5, B3) coincided with the development of fluid inclusions without daughter minerals of salt suggests that sulfide precipitation did not take place until the system was diluted by cooler fluids with lower salinities. However, the observation that the fluid inclusions hosted in minerals before sulfide mineralization (i.e., stages A1, B1, and B2) commonly contain opaque daughter minerals inferred to be sulfides suggests that the ore-forming components were likely derived from the higher temperature magmatic fluids, and the fluids derived from the country rocks mainly contributed to the precipitation of sulfides through mixing and cooling.

The Jinding deposit is a large Zn-Pb deposit hosted in coarse siliciclastic strata of Early Cretaceous and Paleocene ages in the Lanping-Simao basin, western Yunnan, China. The deposit, characterized by fine-grained sphalerite and galena disseminated in sandstones of the Cretaceous Jingxing Formation (K 1j ) and sandstones and limestone breccias of the Paleocene Yunlong Formation (E 1y ), was generally considered as one formed from basinal fluids passively controlled by sedimentary lithofacies and structures. This paper reports sand injection and liquefaction structures occurring as millimeter- to centimeter-wide mineralized sand veins and irregular bodies of light-colored sandstones cutting red-colored sedimentary rocks, and relates them to episodic release of overpressured fluids. The proposed model for the flow of ore-forming fluids differs from previous models in that the fluid flow did not passively follow preexisting pore space and was actively creating new porosity and permeability in the conduits. This implies that the development and distribution of fluid over-pressures in the basin may have exerted a control on mineralization, in addition to lithofacies and structures, and the sand injection and liquefaction structures as described in this paper may be used as indicators of favorable conditions for mineralization.

CO2-rich fluid inclusions containing opaque mineral crystals were found in the Fenghuangshan skarn-porphyry Cu–Fe–Au deposit in Tongling, Anhui, China. These inclusions show variable CO2 contents and are accompanied by aqueous inclusions, both occurring as secondary inclusions in quartz and being locally associated with chalcopyrite mineralization. Laser Raman microspectroscopic analyses confirm the predominance of CO2 in the vapor and the presence of H2S as high as 8 mol%, and identify the opaque mineral with yellow reflectance color in the inclusions as chalcopyrite. More than half of the CO2-bearing inclusions contains chalcopyrite, whereas few of the associated aqueous inclusions do so. The chalcopyrite, occupying less than 1% (volume) of the inclusions, is interpreted to be a daughter mineral, and calculated Cu concentrations in the inclusions range from 0.1 to 3.4 wt%. Copper is inferred to have been transported in CO2-dominated fluids as HS− complexes. The occurrence of chalcopyrite daughter crystals in CO2-rich fluid inclusions indicates that CO2-rich vapor has the capacity of transporting large amounts of Cu, and possibly Au. This finding has significant implications for metal transport and mineralization in hydrothermal systems enriched in CO2, such as orogenic-type and granitic intrusion-related gold deposits.

Based on the detailed geological investigation and record of galleries and drill holes, a new idea has been advanced that granodiorite is earlier than quartz monzodiorite porphyry. Both of them are products of two different magmatic intrusive activities. The analysis results of trace elements show that the Sr content is beyond any other crustal rock and the Th content is beyond that of Ta. The whole-rock analysis indicates that rockbody is rich in CaO and poor in K2O. In the composition of Pb istope of rockbody, the ratio of 207Pb to 204Pb is less than 15.60. All these show that the magma mainly comes from the upper mantle. Ti,Zr,Cr,Nb trace elements and the relation between the Gardini index(τ) and the Rittmann index(σ) indicate that the rockbodies are formed in the orogenic belt and island arc tectonic setting. The summation (ΣREE) and the characteristic value (m(La)/m(Yb)) of the rare earth elements show that the original rock is alkalic basalt. The analysis of the characteristic values of REE and the quantitative modeling calculation indicate that the rock-forming process is dominated by mixed crystallization. According to the analysis on the rock-forming order, magmatic source, tectonic setting and rock-forming process, combined with the achievements of regional rock-controlling structures and division of sublayer of crust, it is believed that Fenghuangshan rock body derives from the deep-seated alkalic basalt magma. The rock-forming process has undertaken sialic and calcareous assimilation and contamination of two different degrees. The rock-forming model belongs to the typical assimilation and fractional cryatalization mechanism.

This paper demonstrates the channels and methods for location prognosis of concealed ore deposits (bodies) in the deep-seated and surrounding districts of productive mines in accordance with their special features. The system frame map is built, from quick exploration in the field to the rapid building of a model indoors. The main research points of location prognosis are also discussed in the paper, which include: 1) integrating the location with the surrounding geological areas, microscopic with macroscopic; 2) analyzing and synthesizing all geological information of different levels, depths and aspects; 3) laying stress on mineralization series; 4) paying attention to the study of the distribution law of ore bodies; 5) introducing the theory of nonlinear dynamics of ore forming processes to ordinary static prognosis; 6) the necessity of the geophysical method in recovering information of concealed ore bodies; 7) the combination of all kinds of geology, geophysics, geochemistry and remote -sensing methods.

The Yunnan Himalayan alkaline-rich porphyry occurs as a compound rockbelt and consists of calca-alkalic, alkaline and peralkaline intrusions. Its origin is in debate. The paper deals with its origin by studying rock’s REE and Sr isotope. Although the rocks are different in their REE contents varying from 77.53 µg/g to 1 798.3 µg/g, they have very similar features in REE parameters. On the triangalar diagram of REEs, the sample dots are concentrated on the end area of light REEs, representing a product of low-degree melting of upper mantle or lower crust materials. The initial 87Sr/86Sr values of rocks vary between 0.706 4 and 0.709 8, showing a feature of mantle-crust mixed source. Moreover, REEs show a logarithmic linear positive correlation between them. This type of correlation strongly supports the fractional-partial melting model. The result of geochemistry inversion shows that the source rock of alkaline-rich porphyry is plagioclase-bearing harzburgite and of mantle-crust mixed type. At the early state of melting, some crust components of the source rock were partially melted into intermediate-acidic magma; with the crust components consumed, the magma evolved to basic.

two stages. Based on microthermometic study, three types of fluid inclusions are divided, namely aqueous inclusions (type I), aqueous-CO2 inclusions (type II) and pure CO2 inclusions (type III). The majority of type I and type II inclusions of stage B and type I inclusions of stage C often appear in groups, representing their primary causes. Besides, near the sulfide veinlet of stage C, many type I inclusions of stage B are arranged in rows along the fracture, showing characteristics of secondary inclusions, these inclusions may be formed at the same time with primary type I inclusions of stage C. So, there may be two main stages of inclusion formation, related to B and C stages, respectively. Stage B develops type I, type II, and type III inclusions, while stage C mainly contains type I inclusions. Homogenization temperatures and salinities of fluids are different in different stages. Mineralization of Guoluolongwa is mainly gold bearing quartz veins and quartz sulfide veins superimposed on the milky quartz veins. The early milky quartz veins of stage A may represent the product of low-grade metamorphic hydrothermal activity. Inclusions of stage B, including all these three types, are primary causes. Coexistence of aqueous and carbonaceous inclusions illustrates the separation of H2 O and CO 2. With a medium homogenization temperature ranging from 240℃ to 300℃, and salinities varing between 18~24% and 3~10% for type I and type II inclusions, respectively, fluid of stage B may be derived from metamorphic hydrothermal fluid. Stage C is characterized by type I inclusions with high salinity, ranging from 15% to 22%, shows that fluid may originate from magmatic hydrothermal, belongs to magmatic hydrothermal period. Homogenization

Comparatively analyzing 47 REE distribution data of the Southern Hunan geosynclinal arkose-silicarenite and various period granitic rocks and the results of their partially melting experiment series in company with the occurence and petrogeochemical features of various period granitic rocks, the authors suggest that all of the above-mentioned salic rocks can be partially melt to produce granitic magma.

The alkali-rich porphyries formed in the structural relaxation epoch of the Himalayan Movement. The tectonic setting and crustal structure in which the rocks formed and the compositional regionization feature of the rocks indicate that the magma formed inside the crust, which is further proved by REE. Sr and Pb isotope data. Combined the aforesaid data with the result of REE inversion, it is suggested as a new opinion that the alkali-rich porphyries were the remelting product of the mixture of mantle rocks intrusing into the crust with crustal material.