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Objectives: To study the molecular epidemiological characteristics of the virus in children with acute viral diarrhea in Changdu of Tibet, China., Methods: Fecal specimens were collected from 96 children with acute diarrhea who visited the People's Hospital of Changdu, Tibet, from November 2018 to November 2020 and were tested for adenovirus, norovirus, astrovirus, sapovirus, and rotavirus. Gene sequencing was performed for the genotypes of these viruses., Results: The overall positive rate of the five viruses was 39% (37/96), among which astrovirus had the highest positive rate of 17%, followed by norovirus (9%), rotavirus (8%), adenovirus (7%), and sapovirus (5%). There was no significant difference in the positive rate of the five viruses among different age groups ( P >0.05). Only the positive rate of astrovirus was significantly different among the four seasons ( P <0.05). For adenovirus, 6 children had F41 type and 1 had C2 type; for norovirus, 6 had GⅠ.3 type, 1 had GⅠ.7 type, 1 had GⅡ.3 type, and 2 had GⅡ.4 Sydney&#95;2012 type; HAstrV-1 type was observed in all children with astrovirus infection; for sapovirus, 1 child each had sporadic GⅠ.2, GⅠ.6, and GⅡ.1 sapovirus and 2 children had unknown type; 6 children had rotavirus G9[P8]., Conclusions: Astrovirus and norovirus are important pathogens in children with acute diarrhea in Changdu, Tibet. The positive rate of adenovirus, norovirus, astrovirus, sapovirus, and rotavirus is not associated with age, and only the positive rate of astrovirus has obvious seasonality. F41 type is the dominant genotype of adenovirus; GⅠ.3 is the dominant genotype of norovirus; HAstrV-1 is the dominant genotype of astrovirus; sporadic GⅠ.2, GⅠ.6, and GⅡ.1 are the dominant genotypes of sapovirus; G9[P8] is the dominant genotype of rotavirus.

A number of iron ore deposits and occurrences are distributed along the southeastern China coast, and they constitute an important Fe metallogenic belt in South China. However, the genesis of this belt remains poorly understood. Here, we present in situ U–Pb laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) ages of garnet from three Fe skarn deposits (Makeng, Luoyang, and Yangshan) to constrain the timing and the genesis of the Fe mineralization. Electron microprobe analyses of garnet in association with magnetite indicate a composition within the grossular-andradite solid solution series. Garnet from two Fe skarn ore samples in the Makeng deposit (430 Mt @ 41.60% Fe) in the western part of the belt yielded two U–Pb ages of 132.9 ± 0.9 Ma and 131.4 ± 1.2 Ma, respectively. Garnet from the Luoyang Fe skarn deposit (14.4 Mt @ 42.44%Fe) in the middle part of the belt yielded ages of 130.7 ± 0.7 Ma and 131.8 ± 1.4 Ma, and garnet from two ore samples in the Yangshan Fe deposit (37.1 Mt @ 42.82% Fe) in the eastern part of the belt yielded similar U–Pb ages of 130.0 ± 1.2 Ma and 132.8 ± 0.9 Ma. The consistent ore-formation ages, similar geological characteristics, and close spatial distribution of these Fe skarn deposits indicate that they constitute a newly recognized ca. 130 Ma Fe skarn metallogenic belt in South China. The garnet ages are in general agreement with the crystallization ages of their associated granitic rocks. The ca. 130 Ma iron skarn belt at the southeastern China coast formed simultaneously and in parallel NE-trending alignment with the Handan-Xingtai Fe skarn deposits in the central North China craton and the Middle-Lower Yangtze River Valley (MLYRV) iron-oxide apatite (IOA) and skarn deposits at the northeastern margin of Yangtze Craton in the northern part of Eastern China. Together, these three ca. 130 Ma Fe metallogenic belts in eastern China constitute an important component of the Cretaceous post-subduction tectono-magmatic Cu–Au–Mo–Sn–W–Fe metallogeny along the eastern Asian continental margin. [ABSTRACT FROM AUTHOR]

Low-temperature polymetallic melts can scavenge gold from aqueous fluids and may be instrumental in the formation of some hydrothermal lode gold deposits. However, this process is yet to be fully appreciated, because of the difficulty in recognizing textural evidence for preexisting melts and a lack of awareness that metallic melts can persist in hydrothermal systems down to very low temperature. The Xiaoqinling gold district, central China, belongs to the world-class East Qinling gold province in the North China Craton. Samples of pyrite from the S60 quartz vein at Xiaoqinling record evidence of multistage gold mineralization, with abundant Au-rich polymetallic droplets trapped as primary melt inclusions in pyrite. We examine this pyrite using a combination of nanoscale secondary ion mass spectrometry, electron probe microanalysis, and scanning electron microscopy. We present textural evidence left by migration of melt inclusions, which can be used to distinguish previously trapped polymetallic melt inclusions from mineral inclusions. We propose that polymetallic melt inclusions trapped early in the crystallization history of the host mineral could migrate to the crystal surface and enter into contact with aqueous fluids. The same effect can also be achieved by fracturing of the host mineral. In this way, relatively low volumes of polymetallic melts can continue to scavenge gold from the multiple pulses of ore fluids that are commonly involved in the formation of large gold deposits. [ABSTRACT FROM AUTHOR]

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

Porphyry-type molybdenum deposits, many of which are in China, supply most of the World's molybdenum. Of particular importance are the molybdenum deposits located in the Qinling-Dabie region that are responsible for more than half of China's molybdenum production. A feature that distinguishes this suite of deposits from the better-known Climax and Endako sub-types of porphyry molybdenum deposits is their formation from CO2-rich magmatic-hydrothermal fluids. The role of CO2, if any, in the transport of molybdenum by these fluids, however, is poorly understood. We conducted experiments on the partitioning of molybdenum between H2O-CO2, H2O-NaCl, and H2O-NaCl-CO2 fluids and a felsic melt at 850 °C and 100 and 200 MPa. Here we show that the exsolution of separate (immiscible) brine and vapor leads to the very high brine DMo values needed for efficient extraction of Mo from the magmas forming Dabie-type porphyry molybdenum deposits. Direct exsolution of immiscible CO2 vapour and brine from magma greatly enriches the brine in molybdenum, a likely factor in the genesis of the Dabie-type porphyry deposits that supply much of the World's molybdenum [ABSTRACT FROM AUTHOR]

The world-class Huize deposit hosts significant germanium (Ge) resources in the Sichuan–Yunan–Guizhou (SYG) Mississippi Valley-type (MVT) Pb–Zn province of China. The distribution and enrichment mechanism of Ge is still poorly understood. In the main ore-forming stage of Huize, we identified six sphalerite colors from C1 (black) to C6 (white) in transmitted light. Two color sequences are confirmed, including C1 → C2 → C3 → C6 and C1 → C2 → C4 → C5 → C6. We used multiple analytical methods to reveal the Ge distribution and incorporation mechanism into sphalerite and the possible enrichment factors. Our results show that Ge occurs as argutite (GeO2), and in the sphalerite crystal lattice, C1 and C3 sphalerite has up to 593 ppm Ge. Two substitution mechanisms, i.e., Ge4+ + □(vacancy) → 2Zn2+ (e.g., C1 and C2) and Ge4+ + 2Cu+ → 3Zn2+ (e.g., C2, C3, C4, and C5), are inferred from the Huize sphalerite. They show different spatial structures of sphalerite and a weak shift of the white line observed by high-resolution X-ray absorption near-edge structure (XANES) spectroscopy. The trace-element composition of sphalerite suggests that reduced sulfur content of the ore-forming fluid contributes to Ge enrichment, followed by high temperature (> 300 °C). [ABSTRACT FROM AUTHOR]

The origin of propylitic fluids in intermediate sulfidation mineralization has not been investigated in detail. Here, we present an extensive petrographic, geochemical, and isotopic (O-H-Sr) study of propylitic epidote, chlorite, and calcite from the Zhengguang intermediate sulfidation epithermal Au-Zn deposit, NE China. Propylitic minerals can be divided into three main types based on their different textural occurrences, namely interstitial cement of clasts of hydrothermal breccia, replacement of primary plagioclase or hornblende, and vein infill of cracks, with late, minor calcite as amygdules in vesicles of andesite representing a fourth textural occurrence. The H-O isotope compositions and mass balance calculations suggest that most propylitic epidote records a dominant (> 50%) contribution of magmatic fluids. The decrease of the average δ18 O H 2 O values equilibrated with different types of epidote (cement 6.8 ± 0.7‰, replacement 5.1 ± 1.1‰, vein 4.5 ± 1.4‰, 1 SD), and the decreasing content of high-temperature elements (e.g., Cu-Mo) from cement, through replacement to vein epidote and chlorite, collectively indicates a decreasing role of magmatic fluids. Replacement epidote and chlorite are enriched in Sr-Mn-Y-Sb, whereas replacement epidote and calcite record similar (87Sr/86Sr)i values to the andesitic host rock, suggesting that replacement minerals inherit certain elements from plagioclase and hornblende, and the Sr isotope signature of the wall rocks. We highlight that propylitic alteration in epithermal deposits can involve significant proportions of magmatic fluids and texturally different alteration mineral types should be considered when using mineral isotopic or chemical compositions to track fluid sources or to vector towards the location of intrusive centers. [ABSTRACT FROM AUTHOR]

The Xingluokeng deposit is the largest granite-related tungsten deposit within the Wuyi metallogenic belt in South China. The Xingluokeng intrusion primarily consists of porphyritic biotite granite, biotite granite, and fine-grained granite. The deposit is represented by veinlet-disseminated mineralization with K-feldspathization and biotitization, alongside quartz-vein mineralization with greisenization and sericitization. This study investigates in-situ analyses of quartz compositions from both the intrusion and hydrothermal veinlets and veins. Trace element correlations indicate that trivalent Al3+ and Fe3+ replace Si4+ within the quartz lattice, with monovalent cations (such as Li+, Na+, and K+) primarily serving as charge compensators. Low Ge/Al ratios (< 0.013) of quartz from granites suggest a magmatic origin. The low Al/Ti and Ge/Ti ratios, accompanied by high Ti contents in quartz, suggest that the porphyritic biotite granite and biotite granite are characterized by relatively low levels of differentiation and high crystallization temperatures. In contrast, the fine-grained granite exhibits a higher degree of fractionation, lower crystallization temperatures, and a closer association with tungsten mineralization. Ti contents in quartz from quartz veins indicate Qz-I formed at temperatures above 400 °C, while Qz-II to Qz-V formed at temperatures below 350 °C. Variations in different generations of quartz, as indicated by Al content and (Al + Fe)/(Li + Na + K) ratio, suggest that Qz-I precipitated from a less acidic fluid with a stable pH, whereas Qz-II to Qz-V originated from a more acidic fluid with notable pH variations. Consequently, alkaline alteration and acidic alteration supplied the essential Ca and Fe for the precipitation of scheelite and wolframite, respectively, highlighting a critical mechanism in tungsten mineralization at the Xingluokeng deposit. [ABSTRACT FROM AUTHOR]

The Yangla Cu skarn deposit is located in the central part of the Jinshajiang Suture Zone, southwest China, with a total reserve of 150 Mt Cu @ 1.03%. The newly discovered antimony orebodies at the depth of Yangla are strictly controlled by the stratum, structure, and lithology, which are lenticular and vein-like within the marble fracture zone, which can provide a window into multistage mineralization and ore genesis at Yangla. Mineralization can be divided into three types, Cu–Pb–Zn (skarn) pyrite, galena, and sphalerite, Cu (porphyry) chalcopyrite and pyrite, and Sb (hydrothermal) stibnite and pyrite. The mineral assemblages were stibnite + pyrite + calcite + quartz ± minor scheelite in antimony ores. This study presents quantitative measurements of the trace element compositions of pyrite and stibnite from the Yangla antimony ores. Analysis of pyrite with electron probe microanalysis (EPMA) showed enrichment in Co, Ni, Sb, As, and Mo, and deficit in its S and Fe contents when compared to the stoichiometric concentrations of S and Fe in pyrite. The Sb-related pyrite may belong to sedimentary-reworked genesis and may be modified by hydrothermal fluids, thereby presenting a certain difference (i.e., crystal morphology, texture, and chemical composition) compared to the skarn and porphyry Cu-related pyrite in the Yangla Cu skarn deposit. Analysis of stibnite with EPMA and inductively coupled plasma-mass spectrometry showed enrichment in As, Pb, Sn, Pb, Cu, and Zn, and presented much higher Sb contents and slightly lower S contents when compared to the stoichiometric concentrations of Sb and S in stibnite. Statistical analysis of the stibnite trace elements showed correlations for the elemental pairs Cu–Pb, As–Sb, and Sn–Pb, and the coupled substitution equations Sb3+ ↔ Cu+ + Pb2+, Sb3+ ↔ As3+, and Sn2+ ↔ Pb2+ may be the major factors governed the incorporating Cu, Pb, As and Sn within the stibnite. Moreover, this study preliminary shows that the antimony mineralization may belong to a carbonate replacement hydrothermal genesis at Yangla. [ABSTRACT FROM AUTHOR]

Actively mined Carlin-type gold provinces are only found in Nevada, USA, and SW China. Herein, we combined nanoscale secondary ion mass spectrometry and atom probe tomography to characterize the distribution of Au and As in pyrite from the micrometer to atomic scales from the Shuiyindong and Lannigou deposits, SW China, and compared this with a representative Nevadan deposit. Results show that invisible gold in both deposits occurs in complex micrometer and nanometer scale zones in the rims of pyrite. Within these oscillatory zones, Au is homogenously distributed rather than occurring as nanoclusters. This confirms that invisible gold is principally structure-bound Au, and that ore fluids were not saturated in Au. Gold deposition from undersaturated, arsenic containing, and ore fluids led to the formation of the giant Carlin-type gold deposits. Although not all high-As zones in the Lannigou pyrite contain high Au, all high-Au zones in both deposits contain elevated As. Arsenic is an important criterion for the incorporation of Au, but just because the fluid had high As does not necessarily imply it had/precipitated a high-Au pyrite. Gold atoms, in the Au–As rich zones of pyrite from both deposits, are surrounded by elevated concentrations of As compared to the matrix. Therefore, As both promotes Au incorporation into the pyrite and controls the maximum amount of structure-bound Au in the pyrite. Comparison of the Guizhou pyrite with Nevada pyrite reflects that the pyrite from the two districts exhibits the consistent nanometer- to atomic-scale characteristics. These similar nanometer- to atomic-scale characteristics further support the Guizhou deposits being classed as "Carlin-type." [ABSTRACT FROM AUTHOR]

Jinchanghe is a Zn-Pb-Fe-Cu skarn deposit in the northern Baoshan block, southwestern China. It is a typical distal skarn deposit with orebodies in the Cambrian Hetaoping Formation limestone and calcareous siltstone. The skarn minerals display a vertical zonation with garnet skarn in the lower part and pyroxene skarn in the upper part. Economic metals are also zoned with Fe at the base, Cu in the middle, and Zn-Pb in the upper part. The skarn formation and Zn-Pb-Fe-Cu mineralization is divided into four paragenetic stages: a pre-ore stage dominated by prograde garnet and pyroxene, an oxide stage represented by Fe mineralization associated with retrograde ilvaite, actinolite and epidote alteration, a sulfide stage characterized with Cu–Zn-Pb sulfides, and a post-ore stage with barren calcite, quartz and chlorite. Fluid inclusion microthermometry indicates that the hydrothermal fluids of the Jinchanghe skarn system evolved from the pre-ore stage (450–480 °C and 11.7–15.5 °C wt% NaCl equiv), through the oxide stage (230–280 °C and 6.5–12.2 wt% NaCl equiv), the sulfide stage (190–230 °C and 1.3–10.3 wt% NaCl equiv), and eventually to the post-ore stage (120–180 °C and 1.6–4.6 wt% NaCl equiv). Correspondingly, the δ18Ofluid values decrease from 1.8–7.1‰ to 1.0–6.4‰, -1.0 to 1.3‰, and -3.6 to -1.4‰. This indicates that the pre-ore fluids comprise a magmatic component but mixed with some meteoric water, and in the later stages meteoric water has become dominant in the hydrothermal system. Zinc and sulfur isotope compositions reveal that the Zn and S forming the sulfides have a dominantly magmatic origin. The coupled decreases of fluid temperature, salinity, and δ18Ofluid values during the mineralization indicate simultaneous mixing with meteoric water and ore precipitation, suggesting that fluid mixing was critical in ore deposition. The gradual increase of δ13CCO2 values in equilibrium with the hydrothermal calcite (-5.2 to -1.6‰) from the sulfide stage to the post-ore is attributed to the reaction between the fluids and the carbonate wallrocks, implying a role that fluid-rock interaction has taken in the sulfide deposition. Fluid mixing and fluid-carbonate reaction are the two major factors controlling the formation of the Jinchanghe deposit. [ABSTRACT FROM AUTHOR]

Many massive sulfide deposits have been discovered in the Upper Paleozoic rift-related volcaniclastic sequence in South China, among which the Yushui copper deposit is the most important due to its high grade. The deposit has been variably attributed as SEDEX (sedimentary exhalative) or MVT (Mississippi valley type). The Yushui copper deposit in Guangdong (South China) contains stratiform bornite-chalcopyrite orebodies (102.1 kt Cu @ 3.5%, 186.6 kt Pb @ 4.29%, 117.6 kt Zn @ 2.91%, and 339 t Ag @ 112 g/t) developed along the contact between Upper Carboniferous dolostone and Lower Carboniferous pebbly quartz sandstone, which indicates a shallow marine deposition environment. The Yushui deposit comprises an upper massive sulfide orebody and a lower stockwork orebody with intense alteration. In this study, we newly identified Carboniferous tuffs and syn-volcanic faults in the footwall, and exhalites in the hanging-wall. Hematite from the Cu ores yielded a U-Pb age of 320 ± 15 Ma (MSWD = 2.1, n = 57), and hydrothermal dolomite yielded a Sm-Nd isochron age of 308.1 ± 4.6 Ma (n = 7; MSWD = 0.94), which constrains the timing of mineralization at Yushui. These ages are coeval with the Carboniferous host rocks. Combining the evidence from the geological features (syn-volcanic faults, volcanic rocks, exhalites) and hematite trace element compositions, we suggest that the Yushui is a shallow marine VMS (volcanogenic massive sulfide) deposit. The Sr-Nd isotope composition of hydrothermal dolomite (εNd ~−12) indicates that the ore-forming materials were originated from the crustal basement. The Yushui copper deposit was likely formed during the Late Carboniferous continental back-arc extension in eastern South China. The regional extension may have caused enhanced heat flow, which promoted fluid convection in the basement rocks. In addition, we suggest that volcanic rocks and disseminated chalcopyrite-pyrite mineralization in the Lower Carboniferous quartz sandstone and exhalites are good indicators for regional VMS prospecting. [ABSTRACT FROM AUTHOR]

The Yueguang gold deposit is located in Fengjia, Xinhua County, Hunan Province, South China. It represents a recently discovered small-scale gold deposit situated in the southwestern region of the Jiangnan Orogenic Belt, west of the Baimashan granitic batholith. In order to discern the characteristics of the ore-forming fluids, the underlying mineralization processes, and establish a foundation for the origin of the Yueguang gold deposit fluid inclusion microthermometry, as well as quartz hydrogen and oxygen isotope analysis, have been carried out on samples obtained from various stages of mineralization. The hydrothermal mineralization stages within the Yueguang gold deposit can be categorized into three stages: (i) the barren, pre-ore quartz-pyrite stage (Stage I), the quartz-pyrite-gold stage (Stage II), and the post-ore quartz-carbonate stage (Stage III), with the second stage being the main mineralization stage. The fluid inclusions identified in samples from the main mineralization stage can predominantly be described with the NaCl–H2O and CO2–NaCl–H2O systems. These inclusions display homogenization temperatures ranging from 158.8 to 334.9 °C, and the fluid salinity ranges from 0.3% to 4.0% (wt.% NaCl equiv.). Laser Raman spectroscopy analysis of individual inclusions further reveals the presence of gas-phases such as CO2, CH4, and N2. Isotopic analysis indicates δ18O fluid values ranging from 3.95 to 6.7 ‰ and δDH2O values ranging from − 71.9 to − 55.7 ‰. These results indicate that the ore-forming fluid of the Yueguang gold deposit belongs to metamorphic hydrothermal fluids of middle-low temperature and low salinity. In the process of ore formation, gold is transported in the form of Au (HS)2− complexes, with gold deposition being driven by fluid immiscibility. Therefore, the Yueguang gold deposit is categorized as an orogenic gold deposit dominated by metamorphic hydrothermal fluid. It may become a new target for gold exploration in the Baimashan region, central Hunan Province. [ABSTRACT FROM AUTHOR]

The Baotan tin deposit (23 Mt @ 0.43% Sn) is located in the Jiuwandashan–Yuanbaoshan area, South China. It is hosted in Neoproterozoic mafic/metasedimentary rocks and apical portions of the Pinying granite pluton. Six alteration and mineralization stages have been identified: pre-ore alteration, cassiterite greisen, cassiterite–tourmaline–quartz vein, cassiterite–quartz vein, cassiterite–sulfide vein, and post-ore quartz/calcite–quartz vein stages. Tin mineralization is mainly in the cassiterite greisen, cassiterite–tourmaline–quartz, and cassiterite–quartz vein stages. The deposit is characterized by widespread tourmalinization. Both pre-ore and ore-stage tourmaline is schorl. Tourmaline from pre-ore tourmaline–quartz nodules has elevated Al2O3 and F contents and Fe/(Fe + Mg) and Na/(Na + Ca) ratios, which are probably controlled by the initial magmatic fluid. Ore-stage tourmaline shows low Al2O3 and F contents and Fe/(Fe + Mg) and Na/(Na + Ca) ratios, which are likely influenced by the surrounding mafic rocks. LA–ICP–MS U–Pb dating on two cassiterite samples from disseminated cassiterite–tourmaline–quartz ore and cassiterite–quartz vein yields 206Pb/238U weighted mean ages of 832 ± 5 Ma and 834 ± 4 Ma (2 σ), respectively. These two dates are consistent with the previously reported zircon U–Pb ages of 834–835 Ma for the Pingying granite, which indicates that tin mineralization is related to the granite. The granite has low magnetic susceptibility and zircon Ce4+/Ce3+ ratios, which are similar to those of Sn-bearing ilmenite-series granites. Our study confirms the Neoproterozoic tin mineralization event in South China and indicates that the Neoproterozoic highly fractionated S-type granites in the southeastern margin of Yangtze Block have a great potential for tin mineralization. [ABSTRACT FROM AUTHOR]

The Zhazixi deposit hosted in sedimentary rocks is a major Sb-W deposit in South China. The mineral scheelite, which can be dated by the U-Pb method, commonly occurs in both tungsten (W)-dominated and antimony (Sb)-dominated ore veins of the deposit. Cathodoluminescence (CL) images reveal the presence of three distinct stages of scheelite (Sch-I, Sch-II and Sch-III) within the deposit. These three scheelites were dated using in-situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), yielding U-Pb ages of 158.1±5.4 Ma and 157.6 ± 4.9 Ma for Sch-I, 155 ± 11 Ma for Sch-II, and 151.3±6.1 Ma for Sch-III. These data suggest that the Zhazixi Sb-W deposit formed during the Late Jurassic (160–150 Ma) rather than the Late Triassic as previously suggested. Considering the temporal similarity with low-temperature hydrothermal Sb deposits in the Xiangzhong metallogenic province (XZMP), the formation of the Sb-W deposit may have followed a similar genetic model, where meteoric groundwater circulated to depth and extracted metals from fertile basement rocks through fluid-rock interaction, resulting in the generation of ore fluids. This study highlights that Late Jurassic low-temperature hydrothermal Sb-polymetallic mineralization in the XZMP is likely more extensive than previously perceived. [ABSTRACT FROM AUTHOR]

Carlin-type gold deposits are among the most important gold-bearing hydrothermal ore systems and are mainly located in Nevada, USA, and southwestern China. However, the source and evolution of the ore-forming fluids for these deposits remain controversial, especially those found within China. In this study, lithium and oxygen isotopic analyses of quartz-hosted fluid inclusions are used to elucidate the source and evolution of the giant Shuiyindong Carlin-type gold deposit. Fluid inclusions trapped in quartz of three distinct genetic stages have low salinity (0.8–6.3wt% NaCl equiv.) and moderate temperature (154–343 °C), but display variable Li and O isotope signatures. The Li and O isotopes of stage I fluids (δ7Li values from + 5.1 to + 9.1‰; δ18O values from + 6.3 to + 10.0‰) indicate predominantly a magmatic source for the initial ore-forming fluids. The large variations of Li and O isotopes of stage II fluids (δ7Li values from + 9.3 to + 16.0‰; δ18O values from + 0.1 to + 7.7‰) suggest that the fluids are controlled by mixing of magmatic fluids and meteoric water, which in turn triggered the precipitation of gold-bearing sulfides. The isotopic compositions of stage III fluids (δ7Li values from + 15.5 to + 22.8‰; δ18O values from − 5.4 to − 2.8‰) confirm that the final fluids are dominated by meteoric water. Furthermore, this work demonstrates that the combined Li–O isotopic analysis of fluid inclusions is a powerful tracer to decode the source and evolution of ore-forming fluids in hydrothermal mineralizing systems. [ABSTRACT FROM AUTHOR]

Scheelite, one kind of common REE-rich and U-bearing hydrothermal mineral, is extensively developed in various types of gold deposits, which can be used to record nature and timing of metallogenesis. The Zhaishang Carlin-like gold deposit in the Qinling Orogen is a giant Au deposit, hosting 127t of Au @ 2.67 g/t with economic concentrations of tungsten and antimony. The study reports two types of scheelite based on the characteristics of petrography and geochemistry. Sch A shows significant oscillatory zoning with dark gray cathodoluminescence (CL) response, whereas Sch B displays patchy textures with brighter CL response. Systematic LA-ICP-MS U–Pb dating of Sch A and Sch B yields ages of 227.1 ± 3.2 Ma and 226.2 ± 6.9 Ma, respectively. The new dates, constraining the Zhaishang Au–W mineralization to ~ 227Ma, coincide well with the western Qinling magmatism, metallogenic and tectonic events. There are significant variations in concentration, the Sch A has low REE content (mean = 41.3 ppm), negative Eu-anomaly with slightly positive Ce-anomaly, whereas Sch B, with small negative or positive Eu-anomaly, has higher REE content (mean = 247 ppm) and higher positive Ce-anomaly. The positive correlation of EuN and EuN* records oxidizing condition during the whole W mineralization event. Additionally, Sch B intergrown with selenides with an increase in the Ce-anomaly supports that the latter has higher oxygen fugacity environment. The Sr isotope signature for scheelite supports that ore-forming metals mostly inherited the host rock component, while the proportion of magma-derived Sr increased in the Sch B. Fluid–rock interactions co-precipitated Au and W caused by the release of Fe and Ca cations and the increase of pH. The study highlights that scheelite as a recorder can help in deciphering the nature and timing of metallogenesis of the studied Au–Sb–W deposit, and thus other similar Au–W deposits. [ABSTRACT FROM AUTHOR]

The basal unit of the Early Cambrian black shale sequence of South China hosts sulfide-rich polymetallic units, non-sulfidic vanadium-rich black shales, sapropelic alginite (combustible shale), barite, and phosphorite. This rock spectrum occurs in a paleoceanographic similar, and stratigraphically correlated, transgressive upwelling setting on the passive continental margin of the Neoproterozoic Yangtze Platform. Several centimeter-thick polymetallic sulfidic units (3–13 wt% Mo+Ni, 100–600 ppm U) have relatively light Mo (δ98/95Mo = 1.1 ± 0.2‰) and relatively heavy U isotope composition (δ238/235U = 0.2 ± 0.1‰). Several meter-thick V-rich shales with multiple ore-grade layers (0.1–0.8 wt% V, < 100 ppm U, Mo and Ni ~ 100 ppm) have isotopically lighter Mo (δ98/95Mo = 0.3 ± 0.4‰) and heavier U composition (δ238/235U = 0.4 ± 0.2‰ and up to 0.7‰). The inverse Mo versus U isotope correlation suggests that both metals were enriched by removal from anoxic to strongly euxinic bottom water in restricted basins along the rifted continental margin. Metal replenishment probably occurred via the cycling of Fe–Mn-oxyhydroxide particles across the redox boundary, with sorption/desorption of Mo (and likely Ni) in a stratified water column. In contrast, V enrichment with much lower Mo, Ni, and U contents, but more fractionated Mo and U isotope composition, reflects non-sulfidic anoxic depositional conditions in a partly open system with higher bottom water renewal rates. While Mo isotope fractionation likely occurred in the water column, U isotope fractionation may dominantly have occurred at the water-sediment interface, perhaps in a benthic organic flocculent layer. These findings indicate that local hydrodynamic control and stratified water column redox conditions may explain the observed variation of metal enrichment (Mo–Ni versus V) in the black shales. Furthermore, the high δ98/95Mo values up to 2.6‰ of the black shales studied and the correlated U and Mo isotope data suggest that Early Cambrian seawater was at least episodically broadly similar to modern seawater. [ABSTRACT FROM AUTHOR]

The formation of Carlin-type gold deposits is poorly constrained, mainly due to the lack of accurate ages for gold mineralization. The Youjiang basin, SW China, represents the world's second-largest Carlin-type gold province after NV, USA. In this paper, we use hydrothermal apatite U–Th–Pb dating to systemically determine the mineralization ages of five Carlin-type gold deposits, namely, Shuiyindong, Jinfeng, Zimudang, Linwang, and Jinya, in the Youjiang basin. The hydrothermal apatite is characterized by intimate intergrowth with gold-bearing sulfides, presence of primary fluid inclusions, irregular morphology and cathodoluminescence zoning, and MREE-enriched composition patterns, indicating that it is clearly associated and coeval with gold mineralization. The concentrations of lattice-bound U and Th in the apatite are highly variable, making it suitable for in situ secondary ion mass spectrometry (SIMS) U–Th–Pb dating. The dating results of hydrothermal apatite from the five deposits show that they formed at ca. 150–140 Ma, contemporary with the widespread felsic magmatism and associated W–Sn mineralization to the east of the Youjiang basin, probably in response to slab breakup of the Paleo-Pacific oceanic plate beneath the South China continental plate. Our case story suggests that hydrothermal apatite could be a robust chronometer for age dating of sedimentary rock-hosted gold mineralization worldwide. [ABSTRACT FROM AUTHOR]

Pyrite, the most common sulfide mineral, is a ubiquitous component of many hydrothermal gold deposits. Geochemical patterns within the refractory pyrite structure represent a valuable repository of information that can help constrain the sources of ore-forming materials, and the evolution of ore-forming processes over time. However, there are still a lot of debates on the mechanisms of physico-chemical processes in ore-forming fluid controlling trace element and sulfur isotope distributions in pyrite during growth. In our manuscript, we use cutting-edge complementary microanalytical methods to understand the origin and evolution of zoned gold-bearing pyrite in samples from the largest gold deposit in the Ailaoshan gold belt, SW China, Zhenyuan (exceeding 100t Au, average grade: 5.3 g/t). Pyrite, arsenopyrite, chalcopyrite, and stibnite are the most abundant sulfide minerals in most orebodies. Of these, pyrite is dominant and is also the most important host for gold. Two types of pyrite can be clearly distinguished: framboidal pyrite and hydrothermal pyrite. Gold is most commonly hosted by hydrothermal pyrite. Framboidal pyrite, mainly hosted by carbonaceous slate, hosts negligible Au, and features low δ34S values ranging from − 35.0 (± 0.9) to − 25.6 (± 1.0)‰. Hydrothermal pyrite is characterized by complex intra-grain zoned textures with alternating As-rich and As-poor bands readily recognizable on backscattered electron images. Scanning electron microscopy and trace-element analyses show that both visible and invisible gold occur only in the As-rich bands. Compared to the As-poor bands (72.1% of Au concentration data < 1.96 ppm, n = 43), the As-rich bands are characterized by far higher concentrations of Au (up to 1420 ppm), Cu, Ag, Sb, and Tl, but lower concentrations of Co and Ni. In-situ sulfur isotope analysis indicates that the δ34S values of As-rich zones range from − 7.3 (± 0.6) to 2.9 (± 0.6)‰ and are similar to those of As-poor zones (from − 6.9 (± 0.7) to 2.8 (± 0.6)‰), but distinct from the framboidal pyrite. Combined with published fluid inclusion data and a probable age for the magmatic event associated with mineralization, these data suggest that magmatic–hydrothermal fluids contributed most ore-forming materials and that periodic boiling led to formation of the rhythmic As-rich and As-poor bands in pyrite. Our data for pyrite constrain the evolution of ore-forming processes and provide new insights into the formation of zoned pyrite, with the conclusions having broad implications for analogous hydrothermal gold deposits worldwide. [ABSTRACT FROM AUTHOR]

This study examines fractures in the Gaosong ore field to determine the main factors affecting the spatial variability in the fracture structure. The attributes of fractures, including the fracture orientation, intensity and intersection density, in the Wuzishan anticline and near the Lotus mountain fault in the Gaosong ore field in the GeJiu ore district were extracted by using a modified circular scanning line method. The fracture intensity and intersection density were analyzed based on the semivariance geostatistics function by using the volume of variation and the amount of relative variability. These parameters quantitatively describe the spatial variability in the fracture structure. The mean and standard variance of fracture intensity and intersection density in the ore field decrease with distance from the Lotus mountain fault, while the coefficient of variation increases. The spatial anisotropy is closely related to the axial direction of the Wuzishan anticline and the orientation of the Lotus mountain fault. The main factors affecting the spatial variability in the fault structure can be determined with the semivariance geostatistics function, and the results are useful for studying the geology of the mining area and can help to construct an accurate structural model to serve the needs of mine production. [ABSTRACT FROM AUTHOR]

The Gongguan deposit in southern Qinling district, central China, is characterized by a Hg and Sb metal association, with proven reserves of 7,543 t Hg and 17,100 t Sb. The Hg-Sb mineralized veins are primarily hosted by local Lower Devonian dolomite. Three primary paragenetic stages have been identified, including (I) pyrite-dolomite-quartz, (II) stibnite-cinnabar-quartz-calcite and (III) post-ore calcite. Dominant mercury and antimony mineralization occurred in stage II. Fluid inclusion microthermometry of quartz and calcite reveal that the Hg-Sb mineralization is associated with a low temperature (142° to 240 °C) and low salinity (< 8.6 wt% NaCl equivalent) fluid, belonging to a H2O-NaCl ± CO2 system. The H–O isotope compositions (δDH2O = −84 to −63‰, δ18OH2O = 1.3 to 12.7‰) of the hydrothermal fluid suggest a mixture of metamorphic fluid and meteoric water. In situ sulfur isotope results of cinnabar (δ34S = 3.4 to 14.5‰), stibnite (δ34S = 4.9 to 10.5‰) and pyrite (δ34S = 3.8 to 5.4‰) indicate sulfur sources from decomposition of diagenetic pyrite and/or the thermochemical sulfate reduction in local sedimentary rocks. In situ obtained 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios (18.006 to 18.362, 15.445 to 15.610 and 37.871 to 38.288, respectively) of stibnite and pyrite substantially differ from those for the regional Carlin Au-Sb and SEDEX Pb–Zn ore deposits. The lead isotope results indicate that the underlying Paleozoic (Silurian to Cambrian) strata and Precambrian metamorphic basement supplied substantial metals for the studied Hg-Sb deposit, whereas the host Devonian carbonates did not contribute significant metals. In summary, we propose that fluid mixing between metamorphic fluid and meteoric water was the main cause for carbonate-hosted Hg-Sb deposition at Gongguan, which reduced the stibnite solubility, oxidized mercury (Hg0 to Hg2+), favoring the process of dedolomitization. [ABSTRACT FROM AUTHOR]

The southern margin of the North China Craton (SNCC) contains 8 giant (> 0.5 Mt Mo resources), 4 large (0.1–0.5 Mt Mo resources) and many small (< 0.1 Mt Mo resources) porphyry Mo deposits. Their magmatism ages are concentrated within 150–131 Ma, but it is unclear what determines the size of porphyry Mo systems. Herein, we synthesize new and existing data for the Mo-bearing intrusions in the SNCC to investigate the optimal conditions for giant deposit formation. These intrusions share similar whole-rock geochemistry characteristics and highly differentiated features, with SiO2 and K2O contents ranging from 68.55 to 79.13 wt.% and 2.63 to 11.18 wt.%, respectively. They share similar lower crustal sources with a variable input of mantle materials. Their εNd(t) and εHf(t) values range from -19.1 to -12.7 and -29.5 to -9.3, respectively, and indicate no relationship with metal fertility. The similar ΔFMQ values calculated from zircon geochemistry also suggest that the porphyry Mo deposit size is unrelated to magma redox conditions. High magmatic water contents and high differentiation features (SiO2 > 73 wt.%) exhibit significant positive correlations with the deposit size. Therefore, we propose that magma with a high water content triggered by intensive fractional crystallization is the fundamental requirement to produce large Mo endowment in the SNCC. This conclusion is consistent with the criteria that pulsed release of mineralizing fluids from a large magma chamber through fractional crystallization play an important role in the formation of giant porphyry Mo deposits in other molybdenum belts in the world. [ABSTRACT FROM AUTHOR]

The relationship between Sn–Ag mineralization and mantle magmatism is a topic of high interest in current ore deposit research. Here, we investigate porphyry-, skarn-, and cassiterite-sulfide type Sn-polymetallic deposits associated with granitoids and vein-type Ag–Pb–Zn deposits hosted in sub-volcanic rocks in the southern Great Xing'an Range (SGXR), northeast China, as a case example. We use He, Ar, and S isotopes and isotopic end-member simulation calculations to determine the contribution of mantle-derived fluids/melts to the ore mineralization. Our He–Ar isotope data demonstrate that the ore-forming fluids are mixtures of shallow crust-derived fluid containing radiogenic 4He but no radiogenic 40Ar and magmatic fluids with mantle-derived 3He and 40Ar. The Pb–Zn–Ag deposits have a higher contribution of magmatic volatiles than the Sn-polymetallic deposits. Sulfide δ34S values of − 2.7 to − 0.6‰ in the Pb–Zn–Ag deposits are consistent with a magmatic sulfur source, whereas sulfides with δ34S values of − 12.2 to − 0.15‰ in the Sn-polymetallic deposits signal a possibly bimodal source of sulfur, i.e., crustal light sulfur mixed with magmatic sulfur. The noble gas compositions of the ore fluids are controlled by crustal thickness, high 3He fluxes (24 to 404 at/s/cm2), and low residence time (1 to 18 Myr) of He in the asthenosphere below the SGXR. Non-equilibrium open-system magma degassing is evidenced by the range of elevated values of 4He/40Ar* ratios (4.8–127). The 3He/heat ratio of the ore fluids from the Sn and Pb–Zn–Ag deposits overlap (0.01–0.76 × 10−2 cm3 STP J−1 (cubic centimeter at standard temperature and pressure per joule) and 0.02–1.08 × 10−2 cm3 STP J−1, respectively), indicating a consequence of conduction of mantle-derived heat across the magma-hydrothermal interface. Furthermore, an increasing abundance of Sn reserves in the SGXR deposits can be equated with an increase in the mantle-derived He component in the ore fluids. These findings suggest that a continuous flux of mantle-derived fluids/melts plays an essential role in Sn–Ag–Pb–Zn mineralization. [ABSTRACT FROM AUTHOR]

We use Sr-Nd isotopes of apatite and trace element compositions of apatite-zircon pairs from a major ore layer in each of three selected magmatic Fe-Ti-V oxide ore deposits (Hongge, Panzhihua, and Taihe) in the Emeishan large igneous province (LIP) in southwestern China to contrast the magmatic controls on ore formation. The average contents of REEs in apatite from a representative ore zone/layer in each of these deposits are higher than the predicted values of apatite crystallizing from a melt with REE contents assumed to be the same as the average values of high-Ti basalts in the Emeishan LIP, confirming that the ore-forming magmas all experienced higher degrees of fractional crystallization by major silicate minerals than the average basalt. The apatites Sm/Yb and Sr/Y indicate that the Panzhihua magma was generated at a shallower depth and experienced higher degree of plagioclase fractional crystallization than Taihe and Hongge. The apatite Sr-Nd isotopes can be reproduced by ~ 8 wt% contamination with Precambrian gneiss-schist in the parental magma for Hongge and by ~ 10 wt% and ~ 25 wt% contamination with marbles in the parental magmas for Panzhihua and Taihe, respectively. A recycled, high-T altered oceanic gabbroic component in the mantle source is a viable alternative to the marble contamination model for Taihe. Coexisting zircon trace element compositions reveal that the parental magma for Taihe (ΔFMQ+4.0) is more oxidized than those for Hongge (ΔFMQ−0.4) and Panzhihua (ΔFMQ−0.7), questioning that magma oxidation played a critical role in the genesis of Fe-Ti-V oxide ore deposits in the Emeishan LIP. [ABSTRACT FROM AUTHOR]

The regolith-hosted rare earth element (REE) deposits in the Nanling Mountain Range, South China, are the most important source of heavy REE (HREE) in the world. A perplexing thing is that only a few of these deposits are relatively enriched in HREE and most of them are actually light REE (LREE)-enriched, although they are all originated from the granitic bedrocks with similar HREE concentrations. This is supposed to be related to the redistribution of REE in the weathered bedrocks due to groundwater-rock interaction, however, it remains enigmatic how REEs are mobilized and fractionated in the interaction. Titanite is an important REE contributor to the regolith-hosted REE deposit. Here, we investigate textural and compositional variations of the titanite from the granitic bedrocks to weathered profiles in the Zuokeng regolith-hosted REE deposit, the largest one that is newly discovered in this region. Together with thermodynamic modelling, we deduce the nature of the fluids, temperature range for titanite alteration, and the mechanism of REE fractionation. Primary titanite is of magmatic in origin and shows relatively high REE contents and negative Eu anomaly on the chondrite-normalized REE pattern. Secondary titanite is commonly associated with chloritized biotite and is characterized by extremely low REE, high Al2O3, F and significant positive Eu anomaly, typical of authigenic origin due to chloritization of biotite under oxidized conditions in supergene environment. From the bedrocks upward to the surface, primary titanite is gradually replaced by calcite, synchysite-(Ce) and TiO2 in the weathered bedrocks. This is interpreted as the result of infiltration of the F, carbonate-rich, alkaline fluids derived from local groundwater through the bedrocks. The irregular dark patches in primary titanite display typical alteration texture and may have formed through fluid leaching of primary titanite. The patches in primary titanite have lower REE concentrations and higher LREE/HREE ratios than magmatic domains, indicating that the groundwater preferentially scavenges HREE from primary titanite, leaving behind LREE in weatherable secondary minerals, such as synchysite-(Ce) and allanite. Mass balance calculation results also confirm that more HREE are lost from weathered bedrocks than LREE. Therefore, the interaction of groundwater and granitic bedrocks may be favorable to enrich LREE rather than HREE in the regolith. This may explain why most regolith-hosted REE deposits like Zuokeng in South China are of predominant in LREE. This study highlights the role of groundwater in mobilizing, fractionating and enriching REE from the granitic bedrocks to resultant regolith-hosted REE deposits. [ABSTRACT FROM AUTHOR]

Oxygen fugacity (fO2) is a critical factor that controls the formation mechanisms of the porphyry Cu deposits. However, the differentiation of the fO2 in post-collisional Au-mineralized and Cu-mineralized porphyry intrusions remains unclear. The post-collisional Jinshajiang–Ailaoshan metallogenic belt hosts several Eocene Cu–Au–Mo porphyry systems including the Yulong Cu, Machangqing Cu, Chang'anchong Cu, and Beiya Au deposits and contains several barren porphyry intrusions, such as the Jianchuan, Putaishan, and Bailiancun granite porphyries. This study compares the zircon chemistry, magmatic fO2, and petrogenesis among the Cu-mineralized, Au-mineralized, and ore-barren porphyries. Our results show that the fO2 of the Cu- and Au-porphyry systems (average ΔFMQ = + 1.59 ± 0.77) is higher than that of the ore-barren (average ΔFMQ = − 0.43 ± 0.91) granite porphyry. Notably, compared to the Au-mineralized porphyries (average ΔFMQ = + 0.99 ± 0.70), the Cu-mineralized porphyries crystallized from more oxidized magma (average ΔFMQ = + 1.89 ± 0.60). All the Cu-mineralized, Au-mineralized, and ore-barren porphyry intrusions originated from partial melting of a thickened lower crust with minor input from the enriched lithospheric mantle-derived melts. The lithosphere of the Au-mineralized and ore-barren porphyry intrusions was influenced mainly by the slab-derived fluids, whereas the lithosphere of the Cu-mineralized porphyry intrusions was metasomatized by slab-derived melts. Therefore, we propose that the parental magmas for the Cu–mineralized porphyry possibly inherited the high oxidation state of the slab-derived melts and then contributed to the high fO2 of the Cu-mineralized granite porphyries. Collectively, the magmatic processes at deep levels played an essential role in determining the fO2 of the granite porphyry, thus controlling the mineralization diversity. [ABSTRACT FROM AUTHOR]

Lithocaps are composed of silicic and advanced argillic altered rocks, and represent an important target for porphyry-epithermal Cu-Au exploration. Previous studies showed that integrating alunite spectral and composition with lithocap whole-rock geochemistry can effectively aid exploration for concealed Cu-Au mineralization. The Zijinshan Cu-Au and Dafanshan alunite deposits are located in the Coastal Volcanic Belt in SE China, where alunite is an indicator of hypogene mineralization and alteration. Detailed mineralogical studies of alunite from these two deposits were performed with short-wavelength infrared spectroscopy (SWIR), whole-rock geochemistry and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). For Zijinshan, wavelength variation of the SWIR alunite absorption peak at 1480 nm is proportional to the whole-rock Na/(Na + K) molar ratio of alunite-bearing samples. Different percentage of alunite and mineral assemblages in the lithocap samples would both affect the wavelength of the SWIR alunite absorption peak at 1480 nm. We suggest that the alunite Ba-Bi contents and the whole-rock Nb/La value (of alunite-bearing rocks) are reliable vectoring tools for detecting magmatic-hydrothermal mineralization center in the district. Comparing the alunite SWIR spectral and mineral geochemical features and whole-rock geochemistry of alunite-bearing rocks between the Zijinshan and Dafanshan deposits, Au–Ag mineralization may be concealed at depth in northwestern Dafanshan. [ABSTRACT FROM AUTHOR]

The Yangchuling porphyry W–Mo deposit is an oxidized tungsten deposit in the Jiangnan tungsten belt, which is the largest tungsten belt in the world. Both W- and Mo-mineralization predominantly occur in the cupola of a monzogranite porphyry with abundant mafic dikes and microgranular mafic enclaves (MMEs). Acicular apatite in MMEs and similar SIMS U–Pb zircon ages of the monzogranite porphyry (149.7 ± 1.1 Ma) and MMEs (148.7 ± 1.3 Ma) suggesting mixing of mafic and felsic melts. Plagioclase phenocrysts are oscillatory zoned with An-rich and An-poor zones with lower 87Sr/86Srinitial values and higher contents of Mg, Ti, and Sr in the An-rich zones and resorption surfaces in An-poor bands. These textures reflect multiple injection of mafic magma into the magma system responsible for the formation of the Yangchuling deposit. Whole rock Sr–Nd isotope data and zircon Hf–O isotope data indicate 60–70% contribution from the enriched mantle and 30–40% from the crust to the ore-forming granitic rocks. The W and Mo endowments of the Yangchuling deposit and other W-Mo deposits in the Jiangnan tungsten belt have different sources. Whereas W is derived from the melting of supracrustal metasedimentary rocks, Mo is contributed by mafic magmas. The latter is inferred from (i) the close relationship of Mo mineralization with mafic dikes and MMEs rather than the more evolved monzogranite porphyry and (ii) higher Mo concentrations in scheelite from MMEs (3020–3406 ppm) than in scheelite from the host monzogranitic porphyry (540–1886 ppm). On the scale of the whole Jiangnan tungsten belt, granitic rocks with more intense Mo mineralization have higher εHf zircon values that demonstrate higher input of mantle material to the deposit-forming granites. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction (SCR) has been one of the most efficient and widely used technologies to remove nitrogen oxides (NOx). SCR research has developed rapidly in recent years, which can be reflected by the dramatic increase of related academic publications. Herein, based on the 10,627 documents from 2001 to 2020 in Web of Science, the global research landscape and hotspots in SCR are investigated based on a comprehensive bibliometric analysis. The results show that SCR research has developed positively; the annul number of articles increase sharply from 246 in 2001 to 1092 in 2020. People's Republic of China and Chinese Academy of Sciences are the most productive country and institution, respectively. The global collaboration is extensive and frequent, while People's Republic of China and USA have the most frequent research cooperation. Applied Catalysis B-Environmental is the leading publication source with 711 records. Five major research areas on SCR are identified and elaborated, including catalyst, reductant, deactivation, mechanism, and others. Zeolite is the most widely studied SCR catalyst, while copper, silver, platinum, and iron are the most popular metal elements in catalyst. Ammonia (NH3) is dominated among various SCR reductants, while hydrocarbon reductant has gained more attention. Sulfur dioxide (SO2) and vapor are the two most concerned factors leading to catalyst deactivation, and catalyst regeneration is also an important research topic. Density functional theory (DFT), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and kinetics are the most widely used methods to conduct mechanism study. The studies on "low temperature," "atomic-scale insight," "elemental mercury," "situ DIRFTS investigation," "arsenic poisoning," "SPOA-34," "Cu-CHA catalyst," "TiO2 catalyst," and "Ce catalyst" have been the hotspots in recent years. [ABSTRACT FROM AUTHOR]

The Huashandong W deposit (7.7 Mt @ 0.26% WO3) is a newly discovered Neoproterozoic scheelite-dominated deposit in the world-class Jiangnan tungsten belt, South China. It occurs largely in metasedimentary rocks near the western margin of the Neoproterozoic Jiuling batholith and mainly consists of W-bearing exogreisen, hydrothermal breccias, and quartz veins. Two episodes of Neoproterozoic granite magmatism are identified with zircon U-Pb ages of ca. 830–823 and 807–804 Ma, respectively. According to cross-cutting relationships and mineral assemblages, two periods of hydrothermal alteration and W mineralization, corresponding to the two episodes of granite magmatism, are recognized in the Huashandong deposit. The early period is dominated by greisenization and associated scheelite mineralization whereas the late period is characterized by sericitization, hydrothermal brecciation, quartz veining, and associated scheelite and minor wolframite mineralization. Molybdenite Re-Os dating indicates that the early- and late-period W mineralization took place at ca. 828 and 800 Ma, respectively. Zircon trace element characteristics suggest that the Jiuling granite crystallized from reduced granitic magmas and has the potential for W mineralization. The petrologic and geochemical features of the Jiuling granite, coupled with the zircon U-Pb ages and Hf isotopic signatures and molybdenite Re-Os ages, imply that the Huashandong W deposit is genetically related to two phases of evolved granodiorites in the Jiuling batholith. The magmatic-hydrothermal nature of both metallogenic events is confirmed by H-O isotopes on hydrothermal quartz. [ABSTRACT FROM AUTHOR]

Tungsten-tin-(rare-metal) deposits are most commonly granite-related and an important source of critical metals. This study describes the fluid evolution in the Tiantangshan Rb-Sn-W deposit, Nanling Range, China, and discusses the implications for mineralizing processes. Mineralization at Tiantangshan is spatially zoned. The greisen roof hosts wolframite-cassiterite quartz veins. The surrounding volcanic rocks host biotite quartz veins (Rb mineralization) crosscut by cassiterite quartz veins and sphalerite-galena quartz veins. The earliest intermediate-density fluids are responsible for the early W-(Sn)-Rb mineralization and evolve towards decreasing homogenization temperature (Th) and ratios of W, Sn, Rb, Cs, Fe, and Mn to Na + K as the fluid migrated from the greisen to the volcanic rocks hosted veins (Th: 420 to 350 °C; salinity: 13 to 4 wt% NaCleq). The spatial distribution of mineralization and fluid paragenesis indicates that precipitation of wolframite, early cassiterite, and Rb-rich biotite was associated with a pH increase during fluid-rock interaction. Late cassiterite and intergrown quartz precipitated from a degassing fluid with lower Th (mainly 360 to 340 °C) and salinity (10 to 2 wt% NaCleq) and with distinctly lower Sn concentrations. Late cassiterite precipitation is therefore likely related with depressurization by brittle failure of the rock leading to simultaneous boiling and meteoric water input. Late Pb–Zn mineralization precipitated from low Th (< 320 °C) and salinity (0 to 2 wt% NaCleq) fluids through extensive mixing with meteoric water. The tempo-spatial development of Rb-Sn-W-Pb–Zn mineralization at Tiantangshan was controlled by a mixing fluid regime, where input of meteoric water gradually increased with time. [ABSTRACT FROM AUTHOR]

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The Dexing porphyry deposit is the largest porphyry Cu–Mo–Au deposit in South China. Biotite composition can record the physicochemical conditions and evolution history of magmatic-hydrothermal system. Biotite from the Dexing porphyry deposit could be divided to three types: primary magmatic biotite (Bi-M), hydrothermal altered magmatic biotite (Bi-A) and hydrothermal biotite (Bi-H). The temperature of Bi-M and Bi-H range from 719 to 767 °C and 690 to 727 °C, respectively. Both magmatic and hydrothermal biotite have high Fe3+/Fe2+ ratios (from 0.18 to 0.24) and XMg values (from 0.57 to 0.66), indicating a high oxygen fugacity. Bi-M has F lower than Bi-A and Bi-H (up to 0.26 wt%), but has Cl (Cl = 0.18–0.30 wt%) similar to Bi-A and Bi-H (Cl = 0.21–0.35 wt%), suggesting that high Cl/F ratios of early hydrothermal fluid may result from the exsolution from high Cl magma. From potassic alteration zone to phyllic and propylitic alteration zones, Cl decreases with increasing Cu, whereas F increases roughly. Therefore, Cl mostly originate from magma, but enrichment of F possibly results from reaction of fluids and Neoproterozoic strata. Negative correlation between Cl and Cu indicates that Cl might act as an important catalyst during Cu mineralization process. Biotite from Dexing has similar halogen compositions to other porphyry Cu-/Mo deposits in the world. Chlorine contents of hydrothermal fluid may be critical for Cu transportation and enrichment, while consumption of Cl would promote Cu deposition. [ABSTRACT FROM AUTHOR]

The Dongnan Cu–Mo deposit, located in the southeast of the Zijinshan ore field (the largest porphyry–epithermal system in Southeast China), represents the complex magmatic and metallogenesis events in the region. The petrogenesis and metallogenesis of granitoids from the deposit are not determined, especially the interactions between ore-bearing (granodiorite porphyry) and barren samples (granodiorite and diorite). In the paper, the whole rock geochemical features shared a similar affinity to the middle-lower content and revealed that they derived from partial melting of the Cathaysian basement with the contribution of mantle materials, even represented that they generated in the plate subduction; LA-ICP-MS zircon U–Pb ages show that these granodiorites, granodioritic porphyry and diorite, were generated during 114–103 Ma. The ore-bearing samples mostly presented εHf(t) of negative values (peak value is −4 to −3) with old two-stage Hf model ages (tDM2) (peak value is 1.10–1.15 Ga), while the barren sample showed slightly negative εHf(t) (peak value is −1 to 0) values with young tDM2 (peak value is 1.00–1.05 Ga). The value of zircon Ce4+/Ce3+ ratio mostly higher than 450 was first verified for the ore-bearing samples in the Dongnan Cu–Mo deposit, and the values of ore-bearing were found to be higher than those from the barren, which suggests that the ore-bearing formed in more oxidized parental magma with higher oxygen fugacity. Based on the geochemical characteristic of the element and isotope, we concluded that the Early Cretaceous multi-phases magmatic activities, low melting temperature and low pressure of pluton, and high oxygen fugacity of zircon, were the favorable conditions for metallogenesis of Dongnan Cu–Mo deposit. [ABSTRACT FROM AUTHOR]

Most porphyry Cu deposits are formed in magmatic arc settings, but some occur in non-arc environments, such as intracontinental settings. The petrogenesis of fertile magmas for porphyry Cu deposits formed in intracontinental settings is still ambiguous. To address this issue, we performed an integrated study of the late Mesozoic porphyry Cu deposits in the South Qinling Orogenic Belt. Zircon U–Pb ages indicate that these late Mesozoic porphyry Cu deposits were formed at 149–142 Ma, in a postcollisional intracontinental setting. εNd(t) (− 4.5 to − 2.7), initial 87Sr/86Sr (0.7046 to 0.7084), and zircon εHf(t) values (− 3.8 to + 2.2) of the late Mesozoic ore-forming and barren rocks suggest that both originate from Meso-Neoproterozoic juvenile lower crust. Whole-rock geochemical and isotopic characteristics indicate that the ore-forming rocks could be formed by the delamination of thickened juvenile lower crust or by the reaction of mantle with normal juvenile lower crust. The barren rocks could be formed by the partial melting of thickened or normal juvenile lower crust. Whole-rock petrochemistry and reversed anorthite contents and Sr isotope data of zoned plagioclase crystals indicate that the mafic magma was recharged into the ore-forming magma chamber. Due to the injection of mafic magma, the ore-forming rocks obtained higher oxygen fugacity, volatiles, water, sulfur, and Cu contents than the barren rocks. According to the regional tectonic evolution, the late Mesozoic porphyry Cu deposits in the South Qinling Orogenic Belt were formed in an extensional environment due to transformation of the tectonic regime. Large-scale lithospheric extension caused asthenospheric mantle upwelling and crust-mantle interaction, providing the crucial metallogenic conditions. Moreover, the injection of mantle-derived mafic magma into the normal magma is a key factor in the formation of the late Mesozoic porphyry Cu deposits in the SQB and similar porphyry systems in an intracontinental setting. [ABSTRACT FROM AUTHOR]

The Baishuizhai, Shituling and Zhushanxia deposits from the Xiazhuang district represent to date the only known occurrences of early Yanshanian (Middle to Upper Jurassic) granite-related high-temperature hydrothermal uranium deposits (175–145 Ma) in the Nanling Metallogenic Belt, South China. Whole-rock geochemistry of ore samples combined with chemical and mineralogical signatures of the hydrothermal phases associated with the U mineralisation characterised a coeval potassic and propylitic alteration fingerprint: (i) the potassic alteration is defined by Na and Ca depletion of the granitic host rock and precipitation of adularia, dioctahedral Fe-muscovite, biotite and secondary quartz; and (ii) the propylitic alteration is marked by whole-rock enrichment in Ca, Fe, Mg, Mn and Ti mainly associated with the precipitation of (Mn)-epidote, Fe-chlorite, fluorapatite, titanite, calcite, APS and Fe-Cu-Pb-Cd-Bi-Mo-sulfide minerals. The high-temperature conditions of the hydrothermal system was demonstrated by the typologies of alteration such as greisen, chlorite geothermometry giving temperature estimates of the ore fluid ranging from 316 to 455°C, minor W mineralisation and the high Zr contents in titanite. Besides, high Rb, Ba, Be, Y, Nb, W, Ta and Mo contents in ore samples, mineral assemblages and chemical signatures of the hydrothermal phases showed evidence for the alteration of fractionated felsic granitic host rocks and the contribution of enriched magmatic-derived fluids. Therefore, these characteristics define a magmatic-hydrothermal genetic model directly related to the intrusion of early Yanshanian granites in the Nanling belt. In this new metallogenic model, highly fractionated high-K calc-alkaline A2-type granitic plutons have provided magmatic fluids, heat and metal sources to the early Yanshanian high-temperature hydrothermal U system. Uranium (±W-Sn-Nb-Ta-Li)-rich fluids were derived from fractionated peraluminous residual silicate melts. Uranium was enriched in a high-temperature, highly saline, F-rich, acid and reducing fluid, and dominantly carried as fluoride complexes. This mineralising fluid percolated in the Indosinian U-rich host granites within the cupolas of early Yanshanian granites and produced characteristic propylitic and potassic (including greisen) hydrothermal alteration. During the hydrothermal alteration, the pH and T variations of the mineralising fluid and the subsequent precipitation of F- and P-bearing hydrothermal phases induced the destabilisation of U complexes, winch eventually triggered the deposition of the U mineralisation. [ABSTRACT FROM AUTHOR]

The carbonate-hosted Pb–Zn deposits in the Sichuan–Yunnan–Guizhou (SYG) triangle region are important Indosinian deposits in South China. The Tianbaoshan deposit is a typical large Pb–Zn deposit in the SYG area and occurs as pipe-like type, hosted by Sinian dolostone. It contains ∼26 Mt Zn–Pb ore (7.76–10.09 % Zn, 1.28–1.50 % Pb and 93.6 g t−1 Ag) and >0.1 Mt Cu ore (2.55 % Cu). In this study, the detailed mineral textures, mineral chemical and sulphur isotopic compositions of the various sulphides have been analysed to constrain the abnormal enrichment mechanism and mineralization relationship. Four mineralization stages have been recognized: Stage 1, minor early pyrite (Py1) with relics and infill of intergranular dolomite or quartz grains; Stage 2, Cu mineralization with coarse-grained, elliptical crystal chalcopyrite (Cp1); (3) Stage 3, Zn mineralization with dark fine-grained sphalerite (Sph1) and light coarse-grained sphalerite (Sph2); and (4) Stage 4, as represented by a quartz–calcite assemblage with galena, minor pyrite (Py2) and chalcopyrite (Cp2). The petrography of the sulphide minerals (Py1, Cp1, Sph1 and Sph2) demonstrates a mutual inclusion relationship. The nature of this relationship from core to rim and their similar sulphur isotope values (5.5–8.3 ‰) indicates a single sulphur source, suggesting that the different mineralization types are the result of different stages of a continuous hydrothermal system. Sphalerite geothermometer study suggests that sphalerite in the Tianbaoshan deposit formed in a low-temperature (<200 °C) hydrothermal system. The low concentrations of Mn and In, low In/Ge ratios and high Fe/Cd ratios in the sphalerite are consistent with those of Mississippi Valley-type (MVT) deposits, but different from those of magmatism-related deposits (e.g. epithermal, skarn and VMS deposits). The positive δ34S values for Py1 (5.1–7.9 ‰), Cp1 (5.1–7.2 ‰), Sph1 (4.7–7.4 ‰), Sph2 (3.9–8.7 ‰), Py2 (4.4–9.3 ‰) and Cp2 (5.0–6.8 ‰) indicate a sulphur source from thermochemical reduction of coeval seawater sulphate. Widely developed dissolved textures (caverns and breccias) with massive sulphide infillings and deformed host rock remnants suggest that replacement of host dolostones by ore fluids was volumetrically significant and the ore formed nearly simultaneously with the cavities. The Tianbaoshan deposit is a typical MVT deposit, which resulted from mixing of a H2S-rich fluid and a metal-rich fluid, with thermochemical sulphate reduction occurring before ore precipitation rather than during ore precipitation. [ABSTRACT FROM AUTHOR]

The Gejiu ore district (~ 3.2 Mt Sn) is located in eastern Yunnan Province, southwest China, and is one of the largest Sn polymetallic ore districts in the world. Athough it has been widely studied, the petrogenesis of ore-related granites is still unclear. In this paper, we present petrological, geochemical, and geochronological data on the granites associated with the Kafang Cu–Sn deposit in the Gejiu ore district (65 Mt Cu ore at a grade of 1.2% and 32 Mt Sn ore at a grade of 0.6%). We use these data to constrain the source, evolution, oxygen fugacity, and tectonic setting of the granitic magmatism. Zircon U–Pb dating yielded an age of 82.8 ± 0.6 Ma for the Kafang granite. The high zircon δ18O values (7.45–9.74‰; mean = 8.80‰) and narrow range of εNd(t) values (–9.0 to –7.7) of the Kafang granite indicate a highly evolved S-type granite derived by partial melting of metamorphic basement rocks of the Jiangnan orogenic belt. Rayleigh fractional crystallization modeling, along with the increase in Hf and Sn contents and decrease in Eu/Eu* values of zircons, record extensive fractional crystallization, and Sn enrichment during magmatic evolution. The Kafang granite was relatively reduced, as evidenced by low zircon Ce/Ce* (10.0–366; mean = 171), (Ce/Nd)N (0.76–8.32; mean = 4.41), △FMQ (–2.5 to 1.2) values, and Fe3+-depleted biotite compositions (Fe3+/(Fe3+ + Fe2+) = 0–0.10), which were favorable for Sn mineralization but not for Cu mineralization. Copper in the Kafang deposit may not have been derived from the granite. Our results suggest that biotite and zircon geochemical compositions, particularly biotite Mg# and A/CNK values and zircon Hf contents, Eu anomalies, and Ce/Ce* and (Ce/Nd)N ratios, are robust tracers of different types of magmatic-hydrothermal ore deposits (i.e., Cu, Mo, W, and Sn). Late Cretaceous magmatism in the Gejiu region and other areas along the southern margin of South China formed an E–W-trending igneous belt that was likely related to northward subduction of the Neo-Tethyan plate rather than northwestward subduction of the Paleo-Pacific plate. [ABSTRACT FROM AUTHOR]

The Dongping gold deposit, located near the northern margin of the North China Craton, contains ore bodies spatially associated with the Devonian Shuiquangou syenite, Cretaceous Shangshuiquan granite, and Archean metamorphic rocks. Major and trace elements and S–Pb isotopes of pyrite from two stages of gold-quartz veins and wall rocks were used to constrain the composition of hydrothermal fluids and metal sources. Stage-1 (early) pyrites are euhedral to subhedral, medium- to coarse-grained, and have low gold contents. Py1a is homogeneous with few fractures, whereas Py1b, which occurs on the edges of Py1a, is porous and has higher metal contents. Stage-2 (late) pyrites are mostly anhedral to subhedral and have smaller grain sizes and higher gold contents than Stage 1. Py2a occurs with sulfide minerals such as galena and chalcopyrite, and Py2b is porous and has the highest gold content (up to 1839 ppm) and smallest grain size. All pyrite samples yield negative δ34S values (− 7.5 to − 3.5‰), reflecting oxidized conditions during mineralization. The ~ 2‰ decrease in δ34S values from Stage 1 (− 4.3‰, − 4.9‰) to Stage 2 (− 7.0‰, − 6.4‰) may reflect a change in the fluid source and/or an increase in fO2. The Pb isotope composition of Stage-1 pyrite is suggestive of a mantle source similar to that of the Shuiquangou syenite, whereas Stage-2 pyrite has more radiogenic Pb isotopic compositions suggestive of an Archean metamorphic source. Combined with previous studies, our trace element and isotopic results indicate that the two stages of pyrite had different sources, with Stage-2 pyrite being more strongly influenced by metasedimentary rocks. We propose that the early stage of low-grade gold mineralization was related to emplacement of the Devonian Shuiquangou syenite, whereas the late stage of high-grade gold mineralization was related to emplacement of the Cretaceous Shangshuiquan granite and leaching of gold from Archean metamorphic rocks. [ABSTRACT FROM AUTHOR]

The Wulong gold deposit (> 80 t Au) is located at the northeastern margin of the North China Craton (NCC). Gold in the most economically important quartz veins (Stages 2 and 3) is associated with a varied assemblage of Bi and Te minerals. Stage 2 is characterized by, in a temporal order, native gold-native bismuth-maldonite-hedleyite, bismuthinite-Bi-sulfotellurides, electrum-hessite-Bi-Pb-Ag sulfosalts, Bi-Pb sulfosalts, and Bi-Pb-sulfotellurides. All of these minerals except maldonite, electrum, hessite, and Bi-sulfosalts are present in Stage 3 veins, which also contain jonassonite and unnamed minerals with stoichiometry of Bi8Te3 and Bi5Te3. These complex Bi mineral assemblages resulted from changes in Pb, Ag, Te and Bi concentrations in reduced hydrothermal fluids both locally and temporally, from Stage 2 to 3. Texturally, approximately 85% of the gold grains are associated with almost all Bi minerals in each main-stage mineralization. Quartz-vein ores from Stages 2 and 3 have high Bi concentrations (up to 7332 ppm) and show a positive correlation between Bi and Au, with Bi/Au ratios > 10. These textural and geochemical associations, together with the occurrence of numerous droplet-like blebs and small inclusion trails of native bismuth and Bi-tellurides with native gold, maldonite, or jonassonite, suggest that Bi-rich melts may have formed from the hydrothermal fluids of Stages 2 and 3, and acted as an Au scavenger in a complex Bi-Au-Pb-Ag-Te system. Hence, the intimate association of Bi and Au at Wulong is the result of Au enrichment via the liquid bismuth collector mechanism. Unlike Wulong, however, other deposits in the NCC, such as Yangzhaiyu (Xiaoqinling district), Guilaizhuang (Jiaodong district) and Dongping (Jidong district), are characterized by low Bi concentrations, and are much richer in Te than Bi, so these systems could not generate low-melting point Bi-rich polymetallic melts. The low-sulfur Bi-Au-Pb-Ag-Te association at Wulong is consistent with that observed in reduced intrusion-related gold systems elsewhere and suggests that hydrothermal fluids may have been derived from the co-located Early Cretaceous diorite-granite porphyry dyke swarm. [ABSTRACT FROM AUTHOR]

The Dashuigou tellurium deposit is the world's only known independent tellurium deposit. By restoring metamorphic rocks' protolith, we seek to understand not only the development and evolution trajectory of the region but also the origin of the relevant deposits. While there are many ways to restore metamorphic rocks' protolith, we take the host metamorphic rocks of Dashuigou tellurium deposit and leverage various petrochemical eigenvalues and related diagrams previously proposed to reveal the deposit's host metamorphic rocks' protolith. The petrochemical eigenvalues include molecular number, Niggli's value, REE parity ratio, CaO/Al2O3 ratio, Fe3+/(Fe3+ + Fe2+) ratio, chondrite-normalized REE value, logarithmic REE value, various REE eigenvalues including scandium, Eu/Sm ratio, total REE amount, light and heavy REEs, δEu, Eu anomaly, Sm/Nd ratio, and silicon isotope δ30SiNBS−28‰, etc. The petrochemical plots include ACMs, 100 mg-c-(al + alk), SiO2-(Na2O + K2O), (al + fm)-(c + alk) versus Si, (FeO + Fe2O3 + TiO)–Al2O3–MgO, c-mg, Al2O3–(Na2O + K2O), chondrite-normalized REE model, La/Yb-REE, and Sm/Nd ratio, etc. On the basis of these comprehensive analyses, the following conclusions are drawn, starting from the many mantle-derived types of basalt developed in the study area of different geological ages, combined with the previously published research results on the deposit's fluid inclusions and sulfur and lead isotopes. The deposit is formed by mantle degassing in the form of a mantle plume in the late Yanshanian orogeny. The degassed fluids are rich in nano-scale substances including Fe, Te, S, As, Bi, Au, Se, H2, CO2, N2, H2O, and CH4, which are enriched by nano-effect, and then rise to a certain part of the crust in the form of mantle plume along the lithospheric fault to form the deposit. The ultimate power for tellurium mineralization was from H2 flow with high energy, which was produced through radiation from the melted iron of the Earth's outer core. The H2 flow results in the Earth's degassing, as well as the mantle and crust's uplift. [ABSTRACT FROM AUTHOR]

Southwestern Guizhou province is one of China's most important distribution areas of Carlin-type gold deposits. The Nibao deposit is a typical gold deposit in southwestern Guizhou. To elucidate the genesis of the Nibao gold deposit, establish a metallogenic model, and guide prospecting prediction, we systematically collected previously reported geological, geochemical, and dating data and discussed the genesis of the Nibao gold deposit, based on which we proposed the metallogenic model. Earlier works show that the Nibao anticline, F1 fault, and its hanging wall dragged anticline (Erlongqiangbao anticline) were formed before or simultaneously with gold mineralization, while F2, F3, and F4 faults postdate gold mineralization. Regional geophysical data showed extensive low resistivity anomaly areas near the SBT (the product of tectonic slippage and hydrothermal alteration) between the P2/P3 and the strata of the Longtan Formation in the SSE direction of Nibao anticline in the lower plate of F1 and hanging wall dragged anticline (Erlongqiangbao anticline), and the anomaly areas are distributed within the influence range of anticlines. Simultaneously, soil and structural geochemistry show that F1, Nibao anticline, Erlongqiangbao anticline, and their transition areas all show good metallogenic elements (Au, As, and S) assemblage anomalies, with good metallogenic space and prospecting possibilities. There are five main hypotheses about the source of ore-forming fluids and Au in the Nibao gold deposit: (1) related to the Emeishan mantle plume activity; (2) source from the Emeishan basalt; (3) metamorphic fluid mineralization; (4) basin fluid mineralization; (5) related to deep concealed magmatic rocks; of these, the mainstream understanding is the fifth speculation. It is acknowledged that the ore-forming fluids are hydrothermal fluids with medium–low temperature, high pressure, medium–low salinity, low density, low oxygen fugacity, weak acidity, weak reduction, and rich in CO2 and CH4. The fluid pressure is 2–96.54 MPa, corresponding to depths of 0.23–3.64 km. The dating results show that the metallogenic age is ~141 Ma, the extensional tectonic environment related to the westward subduction of the Pacific Plate. Based on the above explanation, the genetic model related to deep concealed magmatic rocks of the Nibao gold deposit is established, and favorable prospecting areas are outlined; this is of great significance for regional mineral exploration and studying the genesis of gold deposits. [ABSTRACT FROM AUTHOR]

This study presents zircon U–Pb geochronology and Hf and O isotope data for granitic rocks in the Zijinshan ore field, southwestern Fujian Province, China. The intrusive rocks comprise monzogranite, granite and granodiorite. The magmatic zircon U–Pb ages from these granitic rocks can be divided into four episodes: episodes 1 (157.9–159.9 Ma) and 2 (141 Ma) in the Late Jurassic and episodes 3 (108.1–103.2 Ma) and 4 (97.5–99.7 Ma) in the Middle and Late Cretaceous, respectively. Patterns of rare-earth elements (REE) show enrichment in light REE and obvious negative Eu anomalies. These rocks are also enriched in Rb, Th, U, La, Ce, Nd and Hf, and depleted in Ba, Nb, Sr, P and Ti. The increasing La/Yb ratio and decreasing heavy REE content with decreasing age may imply an increasing contribution of mantle-derived materials from the Late Jurassic to Cretaceous. The zircon ϵ Hf(t) and δ18O values, ranging from −37.7 to −2.8 and 12.0 ‰ to 6.3 ‰, respectively, indicate that the lower crust is an important source of granitic rocks. There was a significant increase in ϵ Hf(t) values and a decrease in δ18O values in the younger magmatic episodes (3 and 4), which ranged from −11.4 to −0.6 and 10.7 to 6.3 ‰, respectively. This suggests an increasing contribution of mantle-derived magma to the crustal melts from the Late Jurassic to late Early Cretaceous in response to the changing regional tectonic setting from compression to extension and an increasing interaction between the crust and mantle. [ABSTRACT FROM AUTHOR]

Background: Polyhalite fertilizer application is an effective way to alleviate a shortage of potassium. This study explored the effects of polyhalite fertilizer application as a total or partial replacement for conventional potassium fertilizer to improve peanut growth and soil quality. Results: The index of peanut yield and its economic benefits, the content and distribution of mineral nutrients in different organs, soil chemical properties, and rhizosphere microbial diversity in response to the treatments were examined. The results show that the M4P6T treatment (60% polyhalite fertilizer replacing potassium chloride as the base fertilizer, and 40% potassium chloride fertilizer applied as a topdressing) increased profit by 7.2% without affecting the yield. The M4P6T treatment significantly improved the accumulation and distribution of potassium, calcium and magnesium in the kernels compared with the M10B treatment (no polyhalite fertilizer; potassium chloride fertilizer only as the base fertilizer). Soil treated with polyhalite fertilizer had higher alpha-diversity values and greater relative abundance of microbes at the phylum and genus levels. Conclusions: Partial substitution of polyhalite for potassium chloride improved soil quality and peanut growth more than did single applications of polyhalite and potassium chloride. [ABSTRACT FROM AUTHOR]

The Maogongdong deposit is located in the giant Dahutang W-Cu-(Mo) ore field, northern Jiangxi Province, South China. It is mainly a vein-type deposit, characterized by early W and late Cu-Mo mineralization, and temporally and spatially associated with Late Mesozoic S-type muscovite granites emplaced into a Neoproterozoic granodiorite batholith and the Shuangqiaoshan Group metasedimentary rocks. Fluid inclusions and H–O isotopes suggest that the early ore-forming fluids of the Maogongdong deposit are mainly magmatic water with relatively high temperature (270–410 °C) and moderate-to-low salinity, while the late ore-forming fluids are mixed with meteoric water, with medium-to-low temperature (160–270 °C) and low salinity. Infrared and conventional microthermometric studies of fluid inclusions of the main tungsten mineralization stage show that the homogenization temperatures of primary fluid inclusion assemblages in wolframite (325 to 355 °C) are about 20 °C higher than those of coexisting scheelite and generally 40 °C higher than those in quartz. The δ34S values of sulfides (− 5.2 to − 1.3 ‰) in the sulfide stage are slightly lower than the magmatic sulfur (− 1.7 to 0.6 ‰) in the pre-ore stage, most likely due to an increase in oxygen fugacity. The low carbon isotope values (− 26.2 to − 15.5 ‰) of fluid inclusions in the tungsten mineralization stage show that a large amount of organic carbon was added before mineralization. Fluid cooling and pressure decrease are the main factors of tungsten ore precipitation, while local boiling may also make a contribution. Mixing of the different fluids led to the formation of copper and molybdenum ores. [ABSTRACT FROM AUTHOR]

Carbonate-hosted Pb–Zn deposits frequently contain significant amounts of critical metals such as germanium in sphalerite. However, the textural and chemical controls leading to Ge enrichment remain poorly constrained. Based on textural observations and laser-ablation (multi-collector) inductively coupled plasma mass spectrometry analysis, we investigate the origin, textural control, and incorporation of Ge in the Zhulingou carbonate-hosted Zn(-Ge) deposit, South China, which contains > 400t Ge at 97.9 ppm. Two hydrothermal stages (I and II) and three textural types of sphalerite (Sp1, Sp2, and Sp3) are recognized in stratabound and stockwork Zn(-Ge) orebodies. Acicular colloform Sp1 formed in stage I, whereas euhedral sector-zoned Sp3 is related to stage II. In acicular-euhedral Sp2, both Sp1 and Sp3 are observed. A large variation of Ge concentrations is observed with an average Ge of 1013 ppm in Sp1, decreasing to 621 ppm in Sp2 and to 492 ppm in Sp3. In the three types of sphalerite, Ge concentrations are not correlated to monovalent cations (Cu and Ag), indicative of unusual substitution mechanisms coupled to divalent cations such as Mn, Pb, or Cd. Trace element distribution, sulfur, and lead isotopes suggest that the deeply circulating brines interacted with Ge-rich basement rocks and mixed with shallow biogenic sulfur: This mixing process was certainly the main factor controlling the Ge endowment. The precipitation of acicular sphalerite was likely controlled by a combination of specific fluid conditions (i.e., low T and pH, and rapid mineral growth rate) and fluid mixing. These conditions leading to the formation of acicular sphalerite were favorable for Ge enrichment, compared to co-existing euhedral grains generally less rich in Ge. [ABSTRACT FROM AUTHOR]

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

Eastern Tianshan is an important nickel ore belt in China, in which large to middle-sized magmatic Ni–Cu sulfide deposits occur spatially in the eastern part. The Baixintan magmatic Ni–Cu sulfide deposit is an important discovery in the western part of Eastern Tianshan, which provides an ideal target to track the evolution of the magmatic mineralization system in this part. The Baixintan intrusion is composed of the northeastern mafic units and the southwestern mafic–ultramafic units. The olivine Fo contents of the Baixintan intrusion range from 81.12 to 84.46 mol.%. Numerical calculations yield a parental magma composition with 9.14 wt.% MgO. The Rayleigh simulation using olivine Fo and Ni contents shows that the parental magma of the Baixintan intrusion has experienced ~ 2% olivine crystallization, and then evolved magma became sulfide-saturated. Calculations by the mass-balance R factor equation using PGE data indicate that the formation of the mafic and mafic–ultramafic units of the Baixintan intrusion resulted from multiple influxes of magmas. The Baixintan intrusion is highly comparable with those mafic–ultramafic intrusions that host large magmatic Ni–Cu sulfide deposits in the eastern part of Eastern Tianshan. The mafic–ultramafic intrusions in the western part of Eastern Tianshan should be carefully evaluated for the potential of hosting large magmatic Ni–Cu deposits. [ABSTRACT FROM AUTHOR]

Permian magmatism occurred widely in the Tarim basin and adjacent areas of NW China, resulting in the emplacement of numerous carbonatite plutons and alkaline rock intrusions, which are likely to have been derived from mantle sources. In addition, at least one large igneous province (LIP) can be recognized in NW China; namely, the ca. 270–290 Ma Tarim LIP, and it can be inferred that the peak age of magma activity is ~ 280 Ma. Therefore, the mantle plume is limited spatially within southern Tianshan and the Tarim Basin and temporally in the Early Permian. Age and field evidence suggest a spatial and temporal relationship between the carbonatites and alkaline rocks within the Tarim LIP, and their genesis is related to the Tarim mantle plume. In this paper, we direct our attention to the mineral assemblages that are related to carbonatites and alkaline rocks which host REE deposits (Wajilitag, Boziguoer) in the northern Tarim Craton. Alkaline rocks typically are related to rifts and/or extensional tectonics, and we suggest that these magmatic and metallogenic events occurred during an extensional regime, possibly related to the Tarim mantle plume event that affected much of South Tianshan during the Permian. [ABSTRACT FROM AUTHOR]