Cu-Zn isotope compositions of hydrothermal sediments from the southern Mid-Atlantic Ridge:implications to the sediment formation and mineral exploration

Six hydrothermal sediment samples were collected from the Xunmei and Tongguan hydrothermal fields along the southern Mid-Atlantic Ridge during the China Ocean Cruise DY46 in 2017.Sulfides and oxides in the samples were separated,and Cu and Zn isotope compositions were analyzed.Results show that the ranges ofδ^(65)Cu values of the bulk sediments,sulfides,and oxides were 0.36‰-2.46‰,-0.21‰-1.10‰,and 0.68‰-1.52‰,respectively.Theδ^(65)Cu values of sulfides in four samples(46II-14,46II-30,46III-06,and 46II-09)were relatively low(-0.21‰-0.50‰),corresponding to theδ^(65)Cu values of sulfides from inactive old hydrothermal chimneys in northern Mid-Atlantic Ridge(n MAR),suggesting that the sulfides in the sediments were originated from collapsed dead chimney mainly.While theδ^(65)Cu values of the other two samples(46III-02 and 46III-08)were relatively high(1.10‰-0.96‰),corresponding to theδ^(65)Cu values for active hydrothermal chimneys sulfides in n MAR,which indicated that the sulfides in these two samples might mainly come from sulfide particles settled from active hydrothermal plume.Because of the high density of sulfide particles,they tended to settle near the hydrothermal vents first.Therefore,highδ^(65)Cu values of sulfides in 46III-02 and 46III-08 implied that undiscovered active hydrothermal vents near the sampling positions of 46III-02 in the Xunmei hydrothermal field and 46III-08 in the Tongguan hydrothermal field.Theδ^(66)Zn values of hydrothermal sediments and sulfides ranged 0.11‰-0.43‰and 0.29‰-0.67‰,respectively.In the four samples from the Xunmei hydrothermal field,a positive correlation was found between the distance of the sampling position from sulfide mineralized spot and the Zn isotopic ratio,showing that the greater the distance from the mineralized spot,the heavier the Zn isotope composition as seen in two samples(46II-30 and 46II-14)of the Xunmei-3 spot.This result aligned with the findings of Wilkinson et al.(2005)and Baumgartner et al.(2023),suggesting that the lower the Zn isotope composition,the closer it is to the hydrothermal vent.However,in the Xunmei hydrothermal field,the Zn isotope composition in the other two samples(46III-02and 46III-06)showed the opposite trend.This indicated that there might be an active hydrothermal vent near the sampling location of sample 46III-02.This observation aligned with the Cu isotope analysis results.This study showed that Cu-Zn isotopes are good indicators for understanding the formation mechanisms of hydrothermal sediments and for locating active hydrothermal vents.

Systemic modulation of skeletal mineralization by magnesium implant promoting fracture healing: Radiological exploration enhanced with PCA-based machine learning in a rat femoral model

The clinical application of magnesium(Mg)and its alloys for bone fractures has been well supported by in vitro and in vivo trials.However,there were studies indicating negative effects of high dose Mg intake and sustained local release of Mg ions on bone metabolism or repair,which should not be ignored when developing Mg-based implants.Thus,it remains necessary to assess the biological effects of Mg implants in animal models relevant to clinical treatment modalities.The primary purpose of this study was to validate the beneficial effects of intramedullary Mg implants on the healing outcome of femoral fractures in a modified rat model.In addition,the mineralization parameters at multiple anatomical sites were evaluated,to investigate their association with healing outcome and potential clinical applications.Compared to the control group without Mg implantation,postoperative imaging at week 12 demonstrated better healing outcomes in the Mg group,with more stable unions in 3D analysis and high-mineralized bridging in 2D evaluation.The bone tissue mineral density(TMD)was higher in the Mg group at the non-operated femur and lumbar vertebra,while no differences between groups were identified regarding the bone tissue volume(TV),TMD and bone mineral content(BMC)in humerus.In the surgical femur,the Mg group presented higher TMD,but lower TV and BMC in the distal metaphyseal region,as well as reduced BMC at the osteotomy site.Principal component analysis(PCA)-based machine learning revealed that by selecting clinically relevant parameters,radiological markers could be constructed for differentiation of healing outcomes,with better performance than 2D scoring.The study provides insights and preclinical evidence for the rational investigation of bioactive materials,the identification of potential adverse effects,and the promotion of diagnostic capabilities for fracture healing.

Geochemical Anomalies Identified by Multifractal Modeling: Implications for Mineral Exploration in the Ziyoutun Cu-Au District, Jilin Province, China

The Ziyoutun Cu-Au district is located in the Jizhong–Yanbian Metallogenic Belt and possesses excellent prospects. However, the thick regolith and complex tectonic settings present challenges in terms of detecting and decomposition of weak geochemical anomalies. To address this challenge, we initially conducted a comprehensive analysis of 1:10,000-scale soil geochemical data. This analysis included multivariate statistical techniques, such as correlation analysis, R-mode cluster analysis, Q–Q plots and factor analysis. Subsequently, we decomposed the geochemical anomalies, identifying weak anomalies using spectrum-area modeling and local singularity analysis. The results indicate that the assemblage of Au-Cu-Bi-As-Sb represents the mineralization at Ziyoutun. In comparison to conventional methods, spectrumarea modeling and local singularity analysis outperform in terms of identification of anomalies. Ultimately, we considered four specific target areas(AP01, AP02, AP03 and AP04) for future exploration, based on geochemical anomalies and favorable geological factors. Within AP01 and AP02, the geochemical anomalies suggest potential mineralization at depth, whereas in AP03 and AP04 the surface anomalies require additional geological investigation. Consequently, we recommend conducting drilling, following more extensive surface fieldwork, at the first two targets and verifying surface anomalies in the last two targets. We anticipate these findings will significantly enhance future exploration in Ziyoutun.

Flotation separation of chalcopyrite from pyrite using mineral fulvic acid as selective depressant under weakly alkaline conditions

Mineral fulvic acid(MFA)was used as an eco-friendly pyrite depressant to recover chalcopyrite by flotation with the use of the butyl xanthate as a collector.Flotation experiments showed that MFA produced a stronger inhibition effect on pyrite than on chalcopyrite.The separation of chalcopyrite from pyrite was realized by introducing 150 mg/L MFA at a pulp pH of approximately 8.0.The copper grade,copper recovery,and separation efficiency were 28.03%,84.79%,and 71.66%,respectively.Surface adsorption tests,zeta potential determinations,and localized electrochemical impedance spectroscopy tests showed that more MFA adsorbed on pyrite than on chalcopyrite,which weakened the subsequent interactions between pyrite and the collector.Atomic force microscope imaging further confirmed the adsorption of MFA on pyrite,and X-ray photoelectron spectroscopy results indicated that hydrophilic Fe-based species on the pyrite surfaces increased after exposure of pyrite to MFA,thereby decreasing the floatability of pyrite.

Influence of the mineralogy of fines on sediment slurrying and slurry behaviors

Fine debris is an important component of natural debris flows.Previous studies focused primarily on the clay minerals found in the fines,and non-clay minerals were often neglected.The effects of mineralogy of fines on debris-mass slurrying and flow behaviors of the resultant slurries are examined herein.The fines(≤0.04 mm)in the<5 mm fraction of the Dongyuege Creek debris-flow deposit is replaced with five other mineral powders with the same maximum particle size.Four types of separate and sequential experiments related to debris slurrying and slurry behaviors are carried out with the prepared clastic materials.The obtained slurrying index ranging from 0.08 to 0.18 shows that non-clay minerals also can function as the fine fractions of debris-flow materials,so long as the requirement of grain size distribution is met.Equidimensional,non-clay minerals making up fines of debris flows can increase the upper solid concentration limits of slurrying(with a maximum of 0.692)and peak values of relative excess water pressure(measured maximum mean peak value is 0.99),leading to higher momentum and higher competence,and thereby more destructive catastrophe.The sediments with platy non-clay mineral-dominated fines have potential for mobilizing into small-to medium-size debris flows with a relatively small competence.Clay minerals in the fines may indeed enhance the liquefaction potential of debris masses by expanding the difference between upper and lower solid concentration limits of slurrying(0.413 and 0.238,respectively,for pure kaolinite),but they significantly suppress the momentum,competence,and destructive power of potential debris flows by lowering upper solid concentration limit of slurrying of debris masses.Alpine catchments rich in non-clay minerals,notably those releasing dolomite into loose sediments,may be more prone to threatening and destructive debris flows.The basin producing clay minerals should be more susceptible to lowmagnitude/high-frequency debris flows with less devastating consequences.

Clinical application of indocyanine green fluorescence imaging in laparoscopic cholecystectomy with common bile duct exploration and J-Tube drainage

BACKGROUND Intraoperative and postoperative biliary injuries remain significant complications of laparoscopic common bile duct exploration(LCBDE).Indocyanine green(ICG)has been shown to significantly reduce injuries caused by intraoperative operational errors.We found that the J-tube can reduce postoperative strictures and injuries to the common bile duct.At this moment,we aim to analyze and compare the complications,efficacy,short-term outcomes,and feasibility of these two adjunctive tools for LCBDE.AIM To evaluate the efficacy of ICG fluorescence imaging In LCBDE and J-tube drainage for patients with common bile duct stones.METHODS We retrospectively collected the clinical case data of patients who were treated at the Hepatobiliary Surgery Department of the Third People’s Hospital of Nantong,affiliated with Nantong University,from January 2016 to January 2021 due to gallbladder stones with choledocholithiasis and who underwent LCBDE combined with a primary suture and either J-tube or T-tube drainage.The patients were divided into groups:Traditional white-light laparoscopy+T-tube group(WL+T-tube),traditional WL+J-tube group,fluorescent laparoscopy+T-tube group(ICG+T-tube)and fluorescent laparoscopy+J-tube group(ICG+J-tube).The preoperative and postoperative clinical case data,laboratory examination data,and intraoperative and postoperative complications(including postoperative bile leakage,electrolyte disturbances,biliary peritonitis,and postoperative infections)and other relevant indicators were compared.RESULTS A total of 198 patients(112 males and 86 females)were included in the study,with 74 patients in the WL+T-tube,47 in the WL+J-tube,42 in the ICG+T-tube,and 35 in the ICG+J-tube.Compared with the other groups,the ICG+J had significantly shorter operation time(114 minutes,P=0.001),less blood loss(42 mL,P=0.02),shorter postoperative hospital stays(7 days,P=0.038),and lower surgical costs(China yuan 30178,P=0.001).Furthermore,patients were subdivided into two groups based on whether a T-tube or J-tube was placed during the surgery.By the third postoperative day,the aspartate transaminase,glutamic pyruvic transaminase,total bilirubin,and direct bilirubin levels were lower in the J-tube group than in the T-tube group(P<0.001).At last,follow-up observations showed that the incidence of biliary strictures at three months postoperatively was significantly lower in the J-tube group than in the T-tube group(P=0.002).CONCLUSION ICG fluorescence imaging in laparoscopic cholecystectomy with common bile duct exploration and J-tube drainage facilitates rapid identification of biliary anatomy and variations,reducing intraoperative bile duct injury,blood loss,surgery duration,and postoperative bile duct stenosis rates,supporting its clinical adoption.

Association between body mass index and lumbar spine volumetric bone mineral density in diabetic and non-diabetic patients

BACKGROUND The association between body mass index(BMI)and bone mineral density(BMD)has shown inconsistent results,varying by sex and skeletal site.Despite normal or elevated bone mass,individuals with type 2 diabetes have an increased risk of hip and vertebral fractures.AIM To assess lumbar spine trabecular volumetric BMD(vBMD)across different BMI categories in individuals with and without diabetes.METHODS This cross-sectional study included 966 men over 50 years old and 1001 postmenopausal women from the Pinggu Metabolic Disease Study.The vBMD of lumbar vertebrae 2 through 4 was measured using quantitative computed tomography.Total adipose tissue,subcutaneous adipose tissue(SAT),visceral adipose tissue(VAT),and lumbar skeletal muscle area were also quantified.RESULTS In men with obesity(P=0.038)and overweight(P=0.032),vBMD was significantly higher in the diabetes group compared to non-diabetic men.After adjusting for age and sex,no significant saturation effect between BMI and BMD was found in participants with diabetes or in women without diabetes.However,a BMI threshold of 22.33 kg/m²indicated a saturation point for vBMD in nondiabetic men.Independent predictors of vBMD in men included age(r=-0.387,P<0.001),BMI(r=0.130,P=0.004),and VAT(r=-0.145,P=0.001).For women,significant predictors were age(r=-0.594,P<0.001),BMI(r=0.157,P=0.004),VAT(r=-0.112,P=0.001),and SAT(r=-0.068,P=0.035).CONCLUSION The relationship between BMI and trabecular vBMD differs in individuals with and without diabetes.Overweight and obese men with diabetes exhibit higher vBMD.

Hydrodynamic Links between Shallow and Deep Mineralization Systems and Implications for Deep Mineral Exploration

Deep mineral exploration is increasingly important for finding new mineral resources but there are many uncertainties.Understanding the factors controlling the localization of mineralization at depth can reduce the risk in deep mineral exploration.One of the relatively poorly constrained but important factors is the hydrodynamics of mineralization.This paper reviews the principles of hydrodynamics of mineralization,especially the nature of relationships between mineralization and structures,and their applications to various types of mineralization systems in the context of hydrodynamic linkage between shallow and deep parts of the systems.Three categories of mineralization systems were examined,i.e.,magmatic-hydrothermal systems,structurally controlled hydrothermal systems with uncertain fluid sources,and hydrothermal systems associated with sedimentary basins.The implications for deep mineral exploration,including potentials for new mineral resources at depth,favorable locations for mineralization,as well as uncertainties,are discussed.

Quantitative Prediction for Deep Mineral Exploration

On reviewing the characteristics of deep mineral exploration, this article elaborates on the necessity of employing quantitative prediction to reduce uncertainty. This is caused by complexity of mineral deposit formational environments and mineralization systems as increase of exploration depth and incompleteness of geo-information from limited direct observation. The authors wish to share the idea of ＂seeking difference＂ principle in addition to the ＂similar analogy＂ principle in deep mineral exploration, especially the focus is on the new ores in depth either in an area with discovered shallow mineral deposits or in new areas where there are no sufficient mineral deposit models to be compared. An on-going research project, involving Sn and Cu mineral deposit quantitative prediction in the Gejiu （个旧） area of Yunnan （云南） Province, China, was briefly introduced to demonstrate how the ＂three-component＂ （geoanomaly-mineralization diversity-mineral deposit spectrum） theory and non-linear methods series in conjunction with advanced GIS technology, can be applied in multi-scale and multi-task deep mineral prospecting and quantitative mineral resource assessment.

Province-scale commonalities of some world-class gold deposits:Implications for mineral exploration

Discovery rates for all metals, including gold, are declining, the cost per significant discovery is increasing sharply, and the economic situation of the industry is one of low base rate. The current hierarchical structure of the exploration and mining industry makes this situation difficult to redress. Economic geologists can do little to influence the required changes to the overall structure and philosophy of an industry driven by business rather than geological principles, However, it should be possible to follow the lead of the oil industry and improve the success rate of greenfield exploration, necessary for the next group of lower-exploration-spend significant mineral deposit discoveries. Here we promote the concept that mineral explorers need to carefully consider the scale at which their exploration targets are viewed. It is necessary to carefully assess the potential of drill targets in terms of terrane to province to district scale, rather than deposit scale, where most current economic geology research and conceptual thinking is concentrated. If orogenic, IRGD, Carlin-style and IOCG gold-rich systems are viewed at the deposit scale, they appear quite different in terms of conventionally adop- ted research parameters. However, recent models for these deposit styles show increasingly similar source-region parameters when viewed at the lithosphere scale, suggesting common tectonic settings. It is only by assessing individual targets in their tectonic context that they can be more reliably ranked in terms of potential to provide a significant drill discovery. Targets adjacent to craton margins, other lithosphere boundaries, and suture zones are clearly favoured for all of these gold deposit styles, and such exploration could lead to incidental discovery of major deposits of other metals sited along the same tectonic boundaries.

Geochemical and Geophysical Data Processing Aided by“Multifractal-Spectrum”Filters for GIS-Based Mineral Exploration

A recently developed method, on the bases of “multifractal spectrum” filters for mineral exploration, is introduced in this paper. The “multifractal spectrum” filters, a group of irregularly shaped filters that are constructed on each processed datum, can be used to separate various types of geochemical and geophysical anomalies. The basic model, with an emphasis on the GIS based implementation and the application to the geochemical and geophysical data processing for mineral exploration in southern Nova Scotia, Canada, indicates its advantage in the separation of multiple anomalies from the background.

A scale-integrated exploration model for orogenic gold deposits based on a mineral system approach

Concept-based orogenic gold exploration requires a scale-integrated approach using a robust mineral system model.Most genetic hypotheses for orogenic gold deposits that involve near-surface or magmatic-hydrothermal fluids are now negated in terms of a global mineral system model.Plausible models involve metamorphic fluids,but the fluid source has been equivocal.Crustal metamorphic-fluid models are most widely-accepted but there are serious problems for Archean deposits,and numerous Chinese provinces,including Jiaodong,where the only feasible fluid source is sub-crustal.If all orogenic gold deposits define a coherent mineral system,there are only two realistic sources of fluid and gold,based on their syn-mineralization geodynamic settings.These are from devolatilization of a subducted oceanic slab with its overlying gold-bearing sulfide-rich sedimentary package,or release from mantle lithosphere that was metasomatized and fertilized during a subduction event,particularly adjacent to craton margins.In this model,CO_2 is generated during decarbonation and S and ore-related elements released from transformation of pyrite to pyrrhotite at about 500 ℃.This orogenic gold mineral system can be applied to conceptual exploration by first identifying the required settings at geodynamic to deposit scales.Within these settings,it is then possible to define the critical gold mineralization processes in the system:fertility,architecture,and preservation.The geological parameters that define these processes,and the geological,geophysical and geochemical proxies and responses for these critical parameters can then be identified.At the geodynamic to province scales,critical processes include a tectonic thermal engine and deep,effective,fluid plumbing system driven by seismic swarms up lithosphere-scale faults in an oblique-slip regime during uplift late in the orogenic cycle of a convergent margin.At the district to deposit scale,the important processes are fluid focussing into regions of complex structural geometry adjacent to crustal-scale plumbing systems,with gold deposition in trap sites involving complex conjugations of competent and/or reactive rock sequences and structural or lithological fluid caps.Critical indirect responses to defined parameters change from those generated by geophysics to those generated by geochemistry with reduction in scale of the mineral system-driven conceptual exploration.

Deep gold mineralization features of Jiaojia metallogenic belt,Jiaodong gold Province:Based on the breakthrough of 3000 m exploration drilling

Recently,continuous breakthroughs have been made about deep gold prospecting in the Jiaodong gold province area of China.Approximately 5000 t of cumulative gold resources have been explored in Jiaodong,which has thus become an internationally noteworthy gold ore cluster.The gold exploration depth has been increased to about 2000 m from the previous<1000 m.To further explore the mineralization potential of the Jiaodong area at a depth of about 3000 m,the Shandong Institute of Geological Sciences has drilled an exploratory drillhole named“Deep drillhole ZK01”to a depth of 3266 m.Hence,as reported herein,the mineralization characteristics of the Jiaojia metallogenic belt have been successfully documented.ZK01 is,to date,the deepest borehole with an gold intersect in China,and constitutes a significant advance in deep gold prospecting in China.The findings of this study further indicate that the depth interval of 2000 m to 4000 m below the ground surface in the Wuyi Village area incorporates 912 t of inferred gold resources,while the depth interval of 2000 m to 4000 m below the surface across the Jiaodong area possesses about 4000 t of inferred gold resources.The Jiaojia Fault Belt tends to gently dip downward,having dip angles of about 25°and about 20°at vertical depths of 2000 m and 2850 m,respectively.The deep part of the Jiaojia metallogenic belt differs from the shallow and moderately deep parts about fracturing,alteration,mineralization,and tectonic type.The deep zones can generally be categorized from inside outward as cataclastic granite,granitic cataclasite,weakly beresitized granitic cataclasite,beresitized cataclasite,and gouge.These zones exhibit a gradual transitional relation or occur alternately and repeatedly.The mineralization degree of the pyritized cataclastic granite-type ore in the deep part of the Jiaojia metallogenic belt is closely related to the degree of pyrite vein development;that is,the higher the pyrite content,the wider the veins and the higher the gold grade.Compared to the shallow gold ores,the deep-seated gold ores have higher fineness and contain joseite,tetradymite,and native bismuth,suggesting that the deep gold mineralization temperature is higher and that mantle-sourced material may have contributed to this mineralization.ZK01 has also revealed that the deep-seated ore bodies in the Jiaojia metallogenic belt are principally situated above the main fracture plane(gouge)and hosted within the Linglong Granite,contradicting previous findings indicating that the moderately shallow gold ore bodies are usually hosted in the contact zone between the Linglong Granite and Jiaodong Group or meta-gabbro.These new discoveries are particularly significant because they can help correct mineralization prospecting models,determine favorable positions for deep prospecting,and improve metallogenic prediction and resource potential evaluation.

Application of Transient Electromagnetic Method with Multi-Radiation Field Sources in Deep Edge Mineral Resources Exploration

In recent years,in order to meet the practical needs of deep edge mine detection with large depth and high precision,transient electromagnetic method(TEM)near emission source detection mode has become an international advanced method(Xue et al.,2020).

Application of Thermolum inescence Techniques to Mineral Exploration—Principles and Advantages

The phenomena of TL are connected with the defect structures of the atomic lattice of the material concerned, and hence are very sensitive to changes in defection of the country rocks status as induced by the mineralizing solution. In other words, the TL of the country rocks from the mineralized area should be quite different from that in the intact barren area.Besides the high sensitivity as mentioned above, advantages of the application of TL techniques to the mineral exploration the easiness in accessing to proper samples, the easy preparation of samples and the quickness in sample processing all amount to convenience and economy of the techniques, indicating the high competitiveness of the TL mineral exploration method, especially during the development stage of mining operations.

A Novel Approach in Hydrogeochemical Exploration for Uranium Mineralization:an Example from West Central Sinai,Egypt

Groundwater in contact with ore deposits may acquire a chemical composition that could be used as a guide for exploration. Eight well-water samples are collected from a known uraniummineralized area near Abu Zenima, west central Sinai to examine the applicability of using the hydrogeochemical technique in the search for uranium mineralization in similar arid areas. The analytical chemical data of the ground water is compared with ground radiometric measurements. The obtained results indicate that groundwater affected by uranium mineralization has a specific relativity of major anions expressed essentially as SO_4〉Cl〉HCO_3 and to a lesser extent as Cl〉SO_4〉HCO_3, associated as a rule with low magnesium content. This association constitutes a signature of uranium mineralization on the composition of groundwater in west central Sinai and could be used as an important exploration guide in the search for uranium deposits in similar areas. Anomalies in Ni, Fe, Zn and Cr and other pathfinder elements in groundwater can furnish geochemical guides to uranium ores. The immobile trace element anomalies, including Zn, Ni and Fe are strongly distributed near the orebody; whereas the relatively mobile trace elements, including Co, U, V and Cr, constitute the dispersion haloes away from the orebody. A new hydrogeochemical discrimination diagram is constructed to be used as a quick and cost effective exploration tool in the search for uranium occurrences in environmentally similar arid areas. Based on the obtained results, a new site for uranium occurrence, west of W. Baba, is delineated and recommended for future detailed geological and geochemical surveying.

Supply-Demand Situation and Exploration of Mineral Resources in China during 2016-2017

During 2016-2017,both the supply and demand of China’s main mineral resources continued to grow.The import of major energy resources and metal ore resources,such as iron ores,crude oil,natural gas,coal and bauxite,except for copper,has shown a substantial increase(Table1).In order to guarantee economic development needs,the

Identification of Sources of Potential Fields with Directional Wavelet Transform:Application to Mineral Exploration

For the sustainable supply of mineral resources, blind deposits are becoming the emphasis of exploration after long-period exploitation of exposed deposits.The collection and analysis of gravity or magnetic data represents one of the cheapest forms of large-scale geophysical exploration.With the identification of potential fields,we can get the map of worms or skeletonizations showing the three-dimension structure of shallow crust,and find the

Identification of Potential Mineral Fields with Directional Wavelet Transform:Application to Mineral Exploration

For the sustainable supply of mineral resources, blind deposits are becoming the emphasis of exploration after long-period exploitation of exposed deposits.The collection and analysis of gravity or magnetic data represents one of the cheapest ways of large-scale geophysical exploration.With the identification of potential mineral fields,we can get the map of worms or skeletonizations showing

Cathodoluminescence and Trace Element Composition of Scheelite from the Middle-Lower Yangtze River Metallogenic Belt(MLYB): Implications for Mineralization and Exploration

The Middle-Lower Yangtze River Metallogenic Belt(MLYB)is known to contain abundant copper and iron porphyry-skarn deposits,with an increasing number of tungsten deposits and scheelite in Fe-Cu deposits being discovered in the MLYB during recent decades.The ore genesis of the newly-discovered tungsten mineralization in the MLYB is poorly understood.We investigate four sets of scheelite samples from tungsten,iron and copper deposits,using CL imaging and LA-ICP-MS techniques to reveal internal zonation patterns and trace element compositions.The REE distribution patterns of four studied deposits show varying degrees of LREE enrichment with negative Eu anomalies.The oxygen fugacity of ore-forming fluid increased in Donggushan,while the oxygen fugacity of ore-forming fluid decreased in Ruanjiawan,Guilinzheng and Gaojiabang.The scheelites from the Donggushan,Ruanjiawan,Guilinzheng and Gaojiabang deposits show enrichment in LREEs and HFSE,with Nb/La ratios ranging from 1.217 to 52.455,indicating that the four tungsten deposits are enriched in the volatile fluorine.A plot of(La/Lu)N versus Mo/δEu can be used to distinguish quartz vein type,porphyry and skarn tungsten deposits.This study demonstrates that scheelite grains can be used to infer tungsten mineralization and are effective in identifying magmatic types of tungsten deposits in prospective mining sites.