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Although advanced spaceborne thermal emission and reflection radiometer multispectral analysis for lithological mapping has been widely applied, traditional methods such as band ratios (BR) and principal component analysis (PCA) are still hampered by cumbersome data processing and poor classification performance. In this study, we utilize improved data inputs for random forest (RF) to extract lithological information of granitoids, which are the predominant rock type for intrusion‐related polymetallic ore deposits in the western Junggar Orogen (NW Xinjiang). Based on spectral absorption features of minerals (e.g., orthoclase, K‐feldspar, hornblende, biotite, plagioclase, and oligoclase), image statistical information and textural features, we tested different combinations of bands, BR, PCA, and texture using RF method, and found that the combination of B13678 + T1 (Mean texture) achieved the highest weighted‐F1 score for granitoids, with an accuracy of 87.32%. Compared to the support vector machine, RF effectively distinguishes lithological differences between different types of granitoid and wallrocks, especially the granite, granodiorite, and alkali granite in the Akebasito intrusion, as well as the alkali granite, plagiogranite and biotite granite in the Karamay intrusions. Moreover, the large number of rare metal deposits (including Cu, Au, Mo, etc.) distributed near the granitoid intrusions in the western Junggar, our result facilitates the analysis of regional tectonic evolution and mineralization controlling. Plain Language Summary: Random forest (RF) is a machine learning method widely used in various fields due to its high classification accuracy and ability to handle high‐dimensional data without overfitting. Advanced spaceborne thermal emission and reflection radiometer data provide important information of related minerals for lithological identification because of its characteristic values for different bands and textures. In this study, ArcGIS was used to extract information from different bands and textures as input data for RF model. Then, the RF model was trained using Python, and the lithological mapping were generated through test data set, and the weighted‐F1 score, and kappa coefficient were compared. The combination of B13678 + T1 yielded the optimal result. Key Points: Based on the spectral data, image statistics and texture, select the most suitable bands combination for lithological mappingLithological identification of granitoids subclasses is very important for the exploration of metal deposits in the western Junggar Orogen [ABSTRACT FROM AUTHOR]

The Wulong deposit is a large gold deposit in the Liaodong peninsula (North China Craton). Silicic and pyrite alterations are well-developed in the deposit and closely related to mineralization. The least altered and silicified microdiorite samples were selected for major and trace element analyses to reveal the elemental migration/enrichment. Pyrites of stage 1 (Py1) were selected for backscattered electron (BSE) imaging and LA-ICP-MS trace element analyses to reveal their possible metallogenic link. Mass balance calculation showed that Al2O3, CaO, Fe2O3, K2O, SiO2, Ag, As, Cu, and Pb were brought in, whereas MgO, Na2O, FeO, Cr, Zn, and Ni were leached out during silicification. LA-ICP-MS trace element analyses show that Py1 has higher Au and Zn contents than Py2 and Py3, Py2 has higher Au and Cu contents than Py1 and Py3, and Py3 has higher Pb, Cu, and As contents than Py1 and Py2. During the process of silicification and pyritization, the depleted H+ concentration and HS− concentration in the ore-forming fluids led to instability of the Au(HS)2− complexes and led to gold precipitation. The depleted sulfur and the reduced temperature during the precipitated of bismuthinite also led to instability of the Au(HS)2− complexes and gold precipitation. [ABSTRACT FROM AUTHOR]

The Riduo intermediate-felsic volcanic rocks are located in the eastern Lhasa terrane in southern Tibet. Zircon U–Pb dating, geochemical and Sr–Nd–Hf isotope analyses were carried out to constrain the age, petrogenesis and magma source of the Riduo magma suite, including andesite, dacitic tuff, and quartz diorite. Zircon U–Pb dating yielded Early Miocene ages of 19.5 ± 0.5 Ma (andesite), 17.6 ± 0.3 Ma (dacitic tuff), and 15.6 ± 0.5 Ma (quartz diorite). Geochemically, this early Miocene suite is adakitic with high SiO2 (55.76–69.46 wt.%), Al2O3 (15.21–16.61 wt.%), Na2O (3.82–4.83 wt.%), Sr (427–1033 ppm), and Sr/Y (24.5–145), but low Y (< 17.8 ppm) and Yb (< 1.82 ppm). The rocks also have low to high K2O (0.44–3.82 wt.%). They are enriched in light rare earth elements (LREEs), large ion lithophile elements (LILEs, e.g. K, Rb, Th and U), but depleted in high-field strength elements (e.g. Nb, Ta) and heavy rare earth elements (HREEs), and have weakly negative to positive Eu anomalies. Isotope analyses reveal that most samples have high whole-rock initial 87Sr/86Sr ratios (0.705611–0.708807), low εNd(t) (−2.25 to −1.15), and positive zircon εHf (t) (+1.29 to +6.49). We suggest that the early Miocene magmas in the eastern Lhasa terrane were likely sourced from post-collisional partial melting of the juvenile lower crust with minor mantle input. The magmas may have been crustal-contaminated during their ascent to the upper crust along the N-S-trending Cona-Riduo rift. [ABSTRACT FROM AUTHOR]

The Qingchengzi Pb‐Zn‐Au (‐Ag) orefield (eastern Liaoning province, NE China) is located in the northeastern margin of the North China Craton. The unconventional Fe isotopes of pyrites were analyzed to unravel the ore‐material source and migration pathway of the ore fluids. Pyrite samples of ores and wallrocks from various deposits in the orefield were collected and the solutions were analyzed by MC‐ICP‐MS. The results show that most pyrite samples contain heavier Fe isotopes than the international pyrite standard IRMM‐014. Within a particular deposit, Fe isotopes become lighter with depth. For example, the pyrite δ56Fe values drop from 0.216 ~ 0.408‰ (150‐m level) to −0.284 to −0.132‰ (210‐m level) at the Zhenzigou deposit. Gold deposits in the orefield also have similar features: At Baiyun (Huangdianzi), the pyrite δ56Fe values (0.394 ~ 0.627‰) of the silicic‐/potassic‐altered rock‐type ore (130‐m level) are significantly higher than that (0.359‰) of the quartz vein‐type ore (440‐m level). The lamprophyre δ56Fe values from different deposits are largely similar (0.040 ~ 0.024‰), whereas those in the wallrocks vary considerably (0.144 ~ 1.238‰). Compiling the pyrite δ56Fe values from many important sedimentary/metamorphic rock units in the region and magmatic‐hydrothermal deposits around the world, we concluded that the Qingchengzi Pb‐Zn‐Au(‐Ag) deposits belong to intrusion‐related magmatic‐hydrothermal type. The spatial fluid isotope variation pattern, and the fact that early‐formed sulfides have lighter isotopes than later ones, suggest that the Qingchengzi ore fluids may have originated from Zhenzigou‐Diannan (hydrothermal center) and outflown to Xiaotongjiapuzi, Gujiapuzi‐Baiyun and Erdao‐Xiquegou areas. The spatial fluid isotope variation pattern also suggests another possible hydrothermal center at Baiyun‐Gujiapuzi. The ability to identify hydrothermal center(s) and delineate fluid migration pathways suggests that pyrite Fe isotopes can serve as a tool for precious and base metals prospecting. [ABSTRACT FROM AUTHOR]

Baiyun deposit is a large gold deposit in the Liaodong Peninsula (North China Craton), containing over 31.7 t of gold. Silicic alteration, K‐feldspar alteration, and pyritization are well developed and closely related with mineralization in Baiyun deposit. Based on field and optical microscopic observations, the alteration styles include quartz + K‐feldspar zone, pyrite + sericite +quartz zone, and chlorite zone from orebody outward. In this study, the quartz, K‐feldspar, and pyrite of pre‐ore, syn‐ore stages 1 and 2 were selected for LA‐ICP‐MS trace element analysis and electron probe microanalysis (EPMA) to reveal the alteration‐mineralization link. Results show that the albite was altered to mainly K‐feldspar and minor secondary quartz at syn‐ore stage 1. Fluid‐rock reaction of the silicic‐potassic alteration may have decreased the fluid oxygen fugacity (fO2), which triggered the gold precipitation. Most of invisible gold occurred in the form of solid solution. At syn‐ore stage 2, albite altered to mainly quartz and minor K‐feldspar. The syn‐ore stage 1 K‐feldspar also altered to minor secondary quartz at syn‐ore stage 2. In addition, the release of sulphur from the syn‐ore stage 1 pyrite was likely another trigger for the gold precipitation. Most of syn‐ore stage 2 invisible gold occurred as nano‐particles. The ore‐forming fluids consist mainly of primary magmatic fluids mixed with minor metamorphic fluids. The ore metals may have sourced mainly from the magmatic fluid and the sillimanite‐mica schist of the Gaixian Formation. [ABSTRACT FROM AUTHOR]

Hydrothermal anomalies related to the Ms8.0 Wenchuan earthquake (EQ) on May 12, 2009, have been widely reported. However, the reported anomalies have not been associated with multi-geosphere analysis, and space–time analysis with crustal seismicity is lacking. In this paper, the space–time variation of hydrothermal parameters, including soil moisture, soil temperature, near-surface relative humidity (RHsig995) and air temperature (TMPsfc), was first extracted and analyzed with the NCEP-FNL reanalysis dataset. The b-value (a seismic parameter from the Gutenberg–Richter law) was calculated and mapped to unravel the crustal stress and rock rupture. Our results reveal a similar time window for hydrothermal anomalies on April 20 and April 30, 2008, and these anomalies are mainly distributed along the southern and middle parts of the Longmenshan fault zone. The surface temperature anomalies lag behind the humidity anomalies, and the accelerating stress accumulation started since June 2007 and lasted for eight to nine months before the mainshock. The b-value mapping shows a segmented difference along strike of the Longmenshan fault, and that regional stress accumulated mainly in the southern parts of the F2 and F3 faults. We propose the occurrence of a complex coupling process led by crustal stress buildup before the Wenchuan EQ. The anomalies are concentrated in the southern part of the surface rupture zone. The prolonged crustal stress accumulation corresponds to the short intermittent hydrothermal response on the Earth's surface before the Wenchuan EQ. Our findings reveal new hydrothermal anomalies in the Earth's surface and atmosphere and explore direct link with seismogenic processes in the crust. [ABSTRACT FROM AUTHOR]

Late Mesozoic granitoids are widely emplaced in the Qinling Orogen on the southern margin of North China Craton (NCC), and can provide important clues on the Late Mesozoic regional geodynamic setting. The Late Jurassic Laoniushan granitic pluton is located in the western end of the southern NCC margin. Zircon U–Pb dating for the granodiorite, quartz diorite, and biotite monzogranite of the pluton yielded 152.5 ± 1.6 Ma, 148.7 ± 1.2 Ma, and 149–146 Ma, respectively. Compilation of the single zircon ages revealed magmatic peaks at ca. 146, 152, and 163 Ma, suggesting multiphase Late Jurassic magmatism. These granitoids are high‐K calc‐alkaline, I‐type, and metaluminous to weakly peraluminous. The rocks show chondrite‐normalised LREE enrichments, HREE depletions and flat HREE patterns, together with (slightly) negative Eu, Nb, Ta, P, and Ti anomalies. The Laoniushan granodiorite and biotite monzogranite have similar REE patterns to the quartz diorite, but the former two have much smaller Eu anomalies than the latter. The negative zircon εHf(t) (−32.6 to −13.7), εNd(t) (−20.7 to −14.3) and crustal‐like whole‐rock trace‐elemental ratios (e.g., Nb/Ta, Th/U, Nb/U, and Ce/Pb), together with the low Mg (MgO = 0.18–2.02 wt%, Mg# = 20–34), Cr (7.00–39.0 ppm), and Ni (0.80–4.00 ppm) contents, suggests that the Late Jurassic granitoids were probably derived from the partial melting of ancient crustal rocks with minor mantle‐derived input. The granodiorite and quartz diorite have similar average εHf(t) (−26.5 and −26.7, respectively), εNd(t) (−20.5 and −20.2, respectively), TDM2(Hf) (2880 and 2885 Ma, respectively) and TDM2(Nd; 2607 and 2578 Ma, respectively), whereas the biotite monzogranite has higher average εHf(t) (−17.1) and εNd(t) (−15.3), and younger TDM2(Hf) (2281 Ma) and TDM2(Nd) (2176 Ma). This suggests that the biotite monzogranite has different magma sources and shallower magma formation depths compared to the granodiorite and quartz diorite. The latter two were likely formed by the partial melting of continental crustal rocks (notably the Taihua Group basement rocks), which was triggered by mantle underplating led by asthenospheric upwelling. The Late Jurassic Laoniushan granitoids may have formed in an extensional setting caused by the Palaeo‐Pacific Plate subduction beneath Eastern China. Commencement of Late Jurassic Laoniushan granitic magmatism likely marked the incipient of lithospheric thinning along the southern NCC margin. Considering also the regional geological evolution, we conclude that although the Laoniushan pluton exhibits spatial–temporal relationships with the nearby Mo (–U) and REE deposits, there is still no unambiguous metallogenic link with these deposits. [ABSTRACT FROM AUTHOR]

The Beishan Orogen (southern Central Asian Orogenic Belt) contains many Palaeozoic gold ore‐hosting intrusions, whose age, petrogenesis and tectonic setting are yet to be well understood. In the Mazongshan arc of the Beishan Orogen, the Jinwozi granodiorite contains high K2O (2.71–5.69 wt%), A/CNK (1.10–1.49) and 10000Ga/Al (mostly >2.6), and has high Nb (15–21 ppm), Zr (337–451 ppm) and light rare earth element contents (∑LREE = 207–257 ppm), but low Sr (92–208 ppm) and negative Eu anomalies (δEu = 0.55–0.70), with calculated Zr saturation temperature of 910–860°C. They exhibit typical features of peraluminous A‐type granites formed in subduction‐related settings. The rocks have high large‐ion lithophile element and Hf contents, but low contents in certain high‐field‐strength elements. In addition, the zircon εHf(t) values (−3.6 to −0.1) indicate partial melting of the crust, while the two‐stage model ages (TDM2 = 1385 to 1611 Ma) and several Palaeozoic magmatic rocks with Mesoproterozoic‐inherited zircon suggest the occurrence of Mesoproterozoic crustal accretion. The ore‐hosting granodiorite pluton at the Jinwozi Au deposit was LA‐ICP‐MS zircon U–Pb dated to be Silurian (ca. 428–422 Ma), older than the previously suggested Late Palaeozoic ages and before the interpreted amalgamation timing of the Beishan Orogen. We propose that the Jinwozi granodiorite is derived from pre‐existing crustal material recycling. [ABSTRACT FROM AUTHOR]

Chalcopyrite is an important sulfide mineral in many types of ore deposits, but matrix‐matched chalcopyrite reference materials for microanalysis are lacking. A new natural chalcopyrite‐bearing specimen (HTS4‐6) was analysed in this study to investigate its potential as a reference material for microbeam sulfur isotope ratio measurement. Detailed textural examination and major element determination showed that the HTS4‐6 chalcopyrite grains have no growth rim or zoning. A total of 607 sulfur isotope ratio spot measurements with secondary ion mass spectrometry (SIMS) conducted on the cruciform sections, and over 120 randomly selected grains yielded highly consistent sulfur isotope ratio. The intermediate measurement precision for four measurement sessions of the 34S/32S measurement results was better than 0.39‰ (2s). Randomly selected chalcopyrite grains of HTS4‐6 were further analysed by LA‐MC‐ICP‐MS, which gave a mean δ34S value of +0.58 ± 0.38‰ (2s, n = 95). The maximum variance (expressed as intermediate precision from SIMS and LA‐MC‐ICP‐MS measurements) is not worse than 0.39‰ (the SIMS value), indicating that HTS4‐6 chalcopyrite is a potential reference material for in situ microbeam sulfur isotope measurements. The mean δ34S value determined by gas source isotope ratio mass spectrometry (GS‐IRMS) is +0.63 ± 0.16‰ (2s, n = 23), consistent with that derived by LA‐MC‐ICP‐MS, and can represent the recommended value for this potential reference material. [ABSTRACT FROM AUTHOR]

The Longmendian Ag–Pb–Zn deposit is located in the southern margin of the North China Craton, and the mineralization occurs mainly in quartz veins, altered gneissic wallrocks, and minor fault breccias in the Taihua Group. Based on vein crosscutting relations, mineral assemblages, and paragenesis, the mineralization can be divided into three stages: (1) quartz–pyrite, (2) quartz–polymetallic sulfides, and (3) quartz–carbonate–polymetallic sulfides. Wallrock alteration can be divided into three zones, i.e., chlorite–sericite, quartz–carbonate–sericite, and silicate. Fluid inclusions in all Stage 1 to 3 quartz are dominated by vapor-liquid two-phase aqueous type (W-type). Petrographic and microthermometric analyses of the fluid inclusions indicate that the homogenization temperatures of Stages 1, 2, and 3 are 198–332°C, 132–260°C, and 97–166°C, with salinities of 4.0–13.3, 1.1–13.1, and 1.9–7.6 wt% NaCleqv, respectively. The vapor comprises primarily H2O, with some CO2, H2, CO, N2, and CH4. The liquid phase contains Ca2+, Na+, K+, SO42−, Cl−, and F−. The sulfides have δ 34 S = – 1.42 to +2.35‰ and 208 Pb / 204 Pb = 37.771 to 38.795, 207 Pb / 204 Pb = 15.388 to 15.686, and 206 Pb / 204 Pb = 17.660 to 18.101. The H–C–O–S–Pb isotope compositions indicate that the ore-forming materials may have been derived from the Taihua Group and the granitic magma. The fluid boiling and cooling and mixing with meteoric water may have been critical for the Ag–Pb–Zn ore precipitation. Geological and geochemical characteristics of the Longmendian deposit indicate that the deposit is best classified as medium- to low-temperature intermediate-sulfidation (LS/IS) epithermal-type, related to Cretaceous crustal-extension-related granitic magmatism. [ABSTRACT FROM AUTHOR]

Secondary ion mass spectrometry (SIMS) has a wide range of applications in Earth Science research, thanks to its high precision and sensitivity, and its capacity in direct insitu micromeasurement. The technique is operated in ultra‐high vacuum (UHV) conditions, especially for the measurement of volatiles such as hydrogen, or the water content in nominally anhydrous minerals (NAMs). To minimize the water background and obtain accurate and precise water contents in NAMs (eg, olivine) critical parameters such as presputtering time, field aperture (FA), dynamic transfer on/off, and primary beam current intensity were investigated for a CAMECA IMS 1280‐HR system. When the chamber vacuum reaches approximately 2 × 10−9 mbar, we set the DTOS OFF, raster size to 50 μm and primary beam current to 5 nA, and used 2000 μm FA and 170‐second presputtering time. Consequently, an approximately 1.2 ppmw water background and 3.6 ppmw limit of detection (LOD) were yielded, from analyzing the San Carlos olivine. Meanwhile, the water content and homogeneity of a range of olivine minerals were characterized for potential use as reference materials for SIMS water content measurement. Olivine water content calibration curve was also established by comparing the Fourier transform infrared (FTIR) results with the SIMS‐measured 16O1H−/16O− ratios. Accuracy and precision of water content measurement were estimated to be better than approximately 10% in this study. [ABSTRACT FROM AUTHOR]

The Eastern Tianshan Orogen (Xinjiang, NW China) in the Central Asian Orogenic Belt (CAOB) is featured by its many Carboniferous-Triassic mafic-ultramafic intrusions and associated magmatic Fe-Ti-V oxide mineralization. In this study, we present the first systematic data comparison on the age and whole-rock geochemistry of the ore-forming mafic-ultramafic complexes at Yaxi, Niumaoquan, Xiangshanxi, and Weiya. Our new age dating on the Yaxi complex indicates that the mineralized gabbro (zircon SHRIMP U-Pb dated 297.3 ± 4.9 Ma) formed in the latest Carboniferous-Early Permian, similar to the diorite (LA-ICP-MS zircon U-Pb dated 308.3 ± 8.6 Ma) and granodiorite (LA-ICP-MS zircon U-Pb dated 304.9 ± 1.7 Ma). The Yaxi complex is the oldest late Palaeozoic mafic-ultramafic intrusion reported so far in the Eastern Tianshan. The mineralized gabbro at Yaxi contains higher average Fe2O3T (20.83 wt.%), TiO2 (5.91 wt.%), and V (523 ppm) contents than its ore-barren counterpart (7.45 wt.%, 0.99 wt.%, and 133 ppm, respectively). These Eastern Tianshan mafic rocks are mildly large ion lithophile element (LILE) enriched and high field-strength element (HFSE) depleted, and with LREE/HREE enrichment (Yaxi: (La/Yb)N = 2.7 ~ 5.37) and subtle positive Eu anomalies (Yaxi: Eu/Eu* = 0.94 to 3.31). This suggests that the Eastern Tianshan mafic-ultramafic magmas were likely derived from an arc/subduction-modified magma source. The E-W trending crustal-scale faults (e.g. the Aqikkuduk fault) may have acted as magma conduits and controlled the magma emplacement. The spatial-temporal distribution of the Eastern Tianshan Fe-Ti-V ore-forming mafic-ultramafic complexes and their petrologic and geochemical features suggest that the latest Carboniferous-Early Permian magmatic phase was likely emplaced in a collision-related compression setting following the Junggar Ocean closure, whereas the late Early Permian phase may have been related to a post-collisional orogenic setting. [ABSTRACT FROM AUTHOR]

We present new laser ablation (LA)‐multicollector‐inductively coupled plasma mass spectrometry detrital zircon U‐Pb age and Hf isotope data of the Triassic sedimentary rocks from the eastern and western sides of the Ailaoshan suture in SW China, which separate the Indochina and South China blocks. Detrital zircon grains of the Lower‐Middle Triassic sequences from western South China show single age population of 280–237 Ma (peak at 254–251 Ma) with mainly positive εHf(t) values (+0.15 to +9.11, ~60%). The Middle Triassic samples from eastern Indochina also contain single age population of 273–236 Ma (peak at 246–242 Ma), but with mainly negative εHf(t) values (−18.95 to −1.83, ~88%). The unimodal detrital zircon age pattern and Hf isotope features suggest that the Permian‐Triassic magmatic arcs had supplied detritus for the Lower‐Middle Triassic sequences on both sides of the Ailaoshan suture. In contrast, the Upper Triassic sequences on the either side of the suture display similar polymodal age populations at 290–230, 500–400, 850–700, 1000–900, 2000–1800, and 2600–2400 Ma. This indicates a dramatic change in detrital provenance across the Middle‐Late Triassic boundary. We interpret this change to be resulted from the closure of the Paleotethyan Ailaoshan Ocean in the early Late Triassic. The ocean closure and consequent Indochina‐South China continent‐continent collision may have connected the drainage systems of the two blocks, leading to the marked similarities in their post‐Middle Triassic sedimentary provenance. Key Points: Lower‐Middle Triassic sedimentary rocks received detritus from Permian‐Triassic magmatic arcsUpper Triassic sedimentary rocks received detritus from both the Indochina‐South China interior and the Permian‐Triassic magmatic arcsFinal closure of the Ailaoshan Ocean was likely completed by the Late Triassic [ABSTRACT FROM AUTHOR]

The Xiuwenghala gold deposit is located in the Beishan Orogen of the southern Central Asian Orogenic Belt. The vein/lenticular gold orebodies are controlled by Northeast‐trending faults and are hosted mainly in the brecciated/altered tuff and rhyolite porphyry of the Lower Carboniferous Baishan Formation. Metallic minerals include mainly pyrite and minor chalcopyrite, arsenopyrite, galena, and sphalerite, whilst nonmetallic minerals include quartz, chalcedony, sericite, chlorite, and calcite. Hydrothermal alterations consist of silicic, sericite, chlorite, and carbonate. Alteration/mineralization processes comprise three stages: pre‐ore silicic alteration (Stage I), syn‐ore quartz‐chalcedony‐polymetallic sulfide mineralization (Stage II), and post‐ore quartz‐calcite veining (Stage III). Fluid inclusions (FIs) in quartz and calcite are dominated by L‐type with minor V‐type and lack any daughter mineral‐bearing or CO2‐rich/‐bearing inclusions. From Stages I to III, the FIs homogenized at 240–260°C, 220–250°C, and 150–190°C, with corresponding salinities of 2.9–10.9, 3.2–11.1, and 2.9–11.9 wt.% NaCl eqv., respectively. The mineralization depth at Xiuwenghala is estimated to be relatively shallow (<1 km). FI results indicate that the ore‐forming fluids belong to a low to medium‐temperature, low‐salinity, and low‐density NaCl‐H2O system. The δ18OH2O values decrease from Stage I to III (3.7‰, 1.7–2.4‰, and −1.7 to 0.9‰, respectively), and a similar trend is found for their δDH2O values (−104 to −90‰, −126 to −86‰, and −130 to −106‰, respectively). This indicates that the fluid source gradually evolved from magmatic to meteoric. δ34S values of the hydrothermal pyrites (−3.0 to 0.0‰; avg. −1.1‰) resemble those of typical magmatic/mantle‐derived sulfides. Pyrite Pb isotopic compositions (206Pb/204Pb = 18.409–18.767, 207Pb/204Pb = 15.600–15.715, 208Pb/204Pb = 38.173–38.654) are similar to those of the (sub)volcanic ore host, indicating that the origin of ore‐forming material was mainly the upper crustal (sub)volcanic rocks. Integrating evidence from geology, FIs, and H–O–S–Pb isotopes, we suggest that Xiuwenghala is best classified as a low‐sulfidation epithermal gold deposit. (i) The Xiuwenghala gold deposit is hosted by volcanic and subvolcanic rocks; (ii) it displays low sulfidation‐type hydrothermal alteration and mineralization; and (iii) the deposit belongs to a low‐sulfidation epithermal deposit. [ABSTRACT FROM AUTHOR]

The article discusses the research on the discovery of pyrite in natural coke which was derived from post-magmatic mafic intrusions found in a coal mine in Yangliu, China. It mentions the chemical compositions of colloidal pyrite, fine pyrite aggregates, and skeletal magmatic pyrite in natural coke. Topics include the exchange between coal and magma, and the use of scanning electron microscope and laser ablation inductively coupled plasma mass spectrometry for rock analysis.

The occurrence of pyrite concretions in the Permian Longtan Formation sheds light on the paragenesis, formation conditions and regional paleoenvironment. We analyzed the mineral and geochemical characteristics of pyrite concretions using scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) from the Longtan Formation shales in Anhui, Eastern China. These pyrite concretions consist of two types, each with a distinct nucleus and outer layer: The former is mainly made up of quartz, bivalve fragments and minor gypsum, ankerite, siderite and pyrite, the latter consists of pyrite (FeS2) in the voids of quartz. Based on the correlation matrix and geochemical/mineralogical affinity, trace elements in the pyrite concretions fall into three groups, that is, I (Sr, Ba, Rb and K) in calcic minerals from bivalve-bearing nucleus, II (Nb, Ta, Zr and Hf) in certain heavy minerals and III (V, Cr, Co and Ni) in pyrites. Mineral assemblage and paragenetic analysis show that the formation of pyrite concretions can be divided into three stages: (1) deposition of bivalve-bearing nucleus, (2) lithification of diatoms and (3) diagenesis of pyrite. Mineral and geochemical indicators suggest that the formation environment of pyrite concretions has undergone a major shift from lagoon with intense evaporation, to strong reducing marsh. [ABSTRACT FROM AUTHOR]

The Proterozoic Xianglushan Fe-Cu orefield (western Sichuan) is located in the Huili–Dongchuan ore belt on the southwestern margin of the Yangtze Block in SW China. The orefield has experienced complex magmatotectonic activities, and hosts a wide variety of Fe oxide-(Cu-Au) deposits. At Xianglushan, the orebodies are made of stratabound magnetite–hematite orebodies superimposed by vein-type chalcopyrite mineralization. The stratabound Fe orebodies are hosted mainly in the Proterozoic volcanic-sedimentary rocks of the lower Yinmin Formation, whilst the Cu vein or stockwork ores were mainly emplaced into the upper part of the footwall volcanic rocks and the lower part of the Fe orebodies. We divided the alteration/mineralization and their fluid inclusions (FIs) into the (I) sodic-calcic alteration, (II) potassic-silicic-sericite alteration and Fe-(Cu) mineralization, and (III) carbonate alteration and Cu mineralization stages. Stage II FIs are mainly two-phase (vapor-liquid), and are featured by medium temperature (348 to 379 °C) and high salinity (21.8 to 22.9 wt % NaCl eqv). Their generally negative calcite δ13C (−4.1‰ to −3.1‰) and δ18OH2O (12.2‰ to 15.3‰) values reveal that the Stage II ore fluids have had a seawater-magmatic fluid mixed source. Late Stage II pyrite has δ34S (−3.3‰ to 13.7‰), 206Pb/204Pb (17.663 to 18.982), 207Pb/204Pb (15.498 to 15.824) and 208Pb/204Pb (37.784 to 38.985), suggesting that the ore-forming materials were derived from dominantly upper crustal source. Stage III FIs are also mainly two-phase (vapor-liquid), and are featured by lower temperature (206 to 267 °C) and salinity (19.0 to 22.5 wt % NaCl eqv) than their Stage II counterparts. The Stage III ore fluids were also likely derived from a meteoric–magmatic mixed source with greater magmatic influence, as indicated by the generally negative calcite δ13C (−6.9‰ to −4.6‰) and δ18OH2O (6.3‰ to 9.2‰) values. Similar to the late Stage II pyrite, the Stage III chalcopyrite δ34S (−4.6‰ to 5.2‰) and Pb isotopes (206Pb/204Pb = 18.198 to 18.987; 207Pb/204Pb = 15.534 to 15.876; and 208Pb/204Pb = 37.685 to 39.476) also suggest a crustal ore-forming material source. Therefore, we suggest that the Fe-(Cu) and Cu mineralization at Xianglushan had similar ore fluid and material sources, although the magmatic influence increased in the later stage. This resembles many Fe-(Cu) deposits in the Huili–Dongchuan ore belt. We conclude that the Xianglushan Fe-Cu deposits are both similar to and different from typical iron-oxide copper gold (IOCG) deposits in terms of alteration styles and hydrothermal mineral assemblages, and are thus best classified as IOCG-like deposits hosted in submarine volcanic-sedimentary rocks. Considering the Mesoproterozoic regional tectonics in the southwestern Yangtze Block, we propose that the Xianglushan ore formation occurred in an intra-/back-arc inversion setting, possibly related to the closure of the Anning ocean basin. [ABSTRACT FROM AUTHOR]

The Liaodong Peninsula is an important mineral province in northern China. Elucidating its lithospheric architecture and structural evolution is important for gold metallogenic research and exploration in the region. In this study, Hf-Nd isotope maps from magmatic rocks are constructed and compared to geological maps to correlate isotopic signatures with geological features. It is found that gold deposits of different age periods in Liaodong are located in areas with specific εHf(t) and εNd ranges (Triassic: from −8 to −4 and from −12 to −8, Jurassic: from −22 to −8 and from −14 to −8, Cretaceous: from −12 to −10 and from −22 to −20), respectively. This may reflect that when the Paleo-Pacific plate was subducted beneath the North China Craton, the magma was derived from the juvenile lower crust and the ancient lower crust, and formed the low-to-moderate hydrothermal Au-(Ag) and Pb-Zn deposits in the Triassic. In the Jurassic, continued subduction may have led to lithospheric thickening. Subsequently, the magma from the ancient lower crust upwelled and formed low-to-moderate hydrothermal Au deposits and porphyry Mo deposits. In the Cretaceous, crustal delamination may have taken place. The magma from the ancient lower crust upwelled and formed various low-to-moderate hydrothermal Au deposits. [ABSTRACT FROM AUTHOR]

The newly discovered Shimensi deposit is a super-large tungsten-copper (W–Cu) deposit with a metal reserve of 742.55 thousand tonnes (kt) W and 403.6 kt Cu. The orebodies are hosted in Mesozoic granites, which intruded the poorly documented Shimensi granodiorite belonging to the Jiuling batholith, the largest intrusion (outcrop > 2500 km2) in South China. Our new SHRIMP (Sensitive High Resolution Ion MicroProbe) zircon dating revealed that the granodiorite at Shimensi (ca. 830–827 Ma) was formed coeval (within analytical uncertainty) or slightly earlier than those in many other places (ca. 819–807 Ma) of the Jiuling batholith. The Neoproterozoic Shimensi granodiorite is peraluminous and high-K calc-alkaline, and contains low P content with no S-type trend (positive P2O5 vs. SiO2 correlation) displayed, thus best classified as peraluminous I-type. The I-type classification is also supported by the zircon REE patterns, largely (93%) positive εHf(t) (−0.87 to 6.60) and relatively low δ18O (5.8–7.7‰). The Neoproterozoic Shimensi granodiorite was formed after the continental arc magmatism (ca. 845–835 Ma), but before the post-collisional S-type granite emplacement (ca. 825–815 Ma) in the Jiangnan Orogen. Therefore, we propose that the Shimensi granodiorite was formed in a collisional/early post-collisional setting. The δ18O increase from the Shimensi granodiorite to many younger (ca. 819–807 Ma) granodiorites (6.0–8.5‰) in the Jiuling batholith probably reflects an increase of supracrustal rock-derived melts with the progress of collision. The Shimensi granodiorite contains low zircon Ce4+/Ce3+ and Eu/Eu*, suggesting a relatively reducing magma that does not favor porphyry Cu–Au mineralization. This left a high background Cu concentration (avg. 196 ppm) in the Neoproterozoic granodiorite, which may have contributed to the Mesozoic W–Cu mineralization, when the granodiorite is intruded and assimilated by the Mesozoic granites. [ABSTRACT FROM AUTHOR]

Pyrite, a mineral that can cause potential environmental issues in coal mining, is commonly found in coal seams around intrusions. In this paper, pyrites from the Yuandian Coal Mine (Huaibei Coalfield, Anhui, Eastern China) were studied using SEM, Raman and LA-ICP-MS. The pyrite morphologic and geochemical data suggest that (1) four pyrite generations are present (framboidal sedimentary pyrites (Py I) in the original coal, coarse-grained magmatic pyrites (Py II) in the intruding diabase, fine-grained metamorphic pyrites (Py III) in the intrusive contact aureole, and spheroid/vein hydrothermal pyrites (Py IV) in the cokeite); and (2) concentrations of cobalt, nickel, arsenic, selenium, lead and copper in the metamorphic pyrites are much higher than the other pyrite generations. We propose that mafic magmatism is the main contributor of the toxic elements to the intrusion-related cokeite at Yuandian. [ABSTRACT FROM AUTHOR]