China's requisition-compensation balance strategy has dramatically reshaped cropland spatial patterns,drawing multidisciplinary research attention.However,existing studies predominantly emphasize horizontal distri...China's requisition-compensation balance strategy has dramatically reshaped cropland spatial patterns,drawing multidisciplinary research attention.However,existing studies predominantly emphasize horizontal distribution,overlooking the significant influence of slope gradient on cropland spatial patterns.This paper proposes a slope location quotient(SLQ)index that reflects the relative advantage of cropland distribution and explores the slope grade difference of cropland spatial patterns in China at the county scale.The analysis adopts 30-m resolution digital elevation model with land cover data,taking 2672 counties with cropland ratio>1%as study units.The temporal scope covers 1990 and 2020,with slope gradients categorized into five grades:0°~2°,2°~6°,6°~15°,15°~25°,and 25°~90°.Results show that:1)The inverse correlation between cropland area and slope gradient remained stable throughout the study period,with the variation in cropland area frequency across slope grades being less than 1%.2)The spatial patterns of SLQ in 1990 and 2020 both transited stepwise with slope gradient,while≤2°and>6°slopes exhibited opposing patterns.3)The mean absolute variation of SLQ during 1990-2020 increased with slope gradient(R2=0.926,p<0.01).Particularly for slope grades>15°,the mean absolute variation reached 0.26(for 15°~25°)and 0.43(for 25°~90°),respectively,and displayed a distinct southward-increasing and northwarddecreasing pattern.This study offers novel slopegradient perspectives for analyzing cropland spatial patterns.To enhance cropland protection benefits,reversing the steep cropland SLQ surge in southern China is recommended.展开更多
The rapid advancement of modern science and technology,coupled with the recent surge in new-energy electric vehicles,has significantly boosted the demand for lithium.This has promoted the development and efficient uti...The rapid advancement of modern science and technology,coupled with the recent surge in new-energy electric vehicles,has significantly boosted the demand for lithium.This has promoted the development and efficient utilization of lepidolite as a lithium source.Therefore,the processes for the flotation of lepidolite have been studied in depth,particularly the development and use of lepidolite flotation collectors and the action mechanism of the collectors on the lepidolite surface.Based on the crystal-structure characteristics of lepidolite minerals,this review focuses on the application of anionic collectors,amine cationic collectors(primary amines,quaternary ammonium salts,ether amines,and Gemini amines),and combined collectors to the flotation behavior of lepidolite as well as the adsorption mechanisms.New directions and technologies for the controllable flotation of lepidolite are proposed,including process improvement,reagent synthesis,and mechanistic research.This analysis demonstrates the need for the further study of the complex environment inside lepidolite and pulp.By using modern analytical detection methods and quantum chemical calculations,research on reagents for the flotation of lepidolite has expanded,providing new concepts and references for the efficient flotation recovery and utilization of lepidolite.展开更多
The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with G...The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with GPS field collected data in the area of Xiaowan-Dachaoshan Reservoirs of Lancangjiang River cascaded Hydropower Area. Consequently, the land-cover is divided into five subclasses, namely water, paddy field and wetland, bare dryland and sparse shrub, secondary forest and density forest. The result showed that the areas of bare land, upland and secondary forest decreased in 1988-1996, whereas from 1996 to 2000, water body and density forest keep invariability while the areas of paddy field and wetland, bare dryland and sparse scrub increasing and the area of secondary forest decrease; Features of reciprocal transformation between density forest and other type of land-cover had two points, i.e. secondary forest, bare dryland and sparse shrub converted to density forest; and density forest converted to secondary forest and paddy field and wetland. It reflects the dynamic variation of density forest; the area which slope less than 8° and greater than 15° shows bigger variation, however, less change in 8°-15°.展开更多
In order to evaluate the productivity of reclamation lands in mining districts,field investigation and spatial information technique were adopted to investigate influence factors of land.Based on the collected data of...In order to evaluate the productivity of reclamation lands in mining districts,field investigation and spatial information technique were adopted to investigate influence factors of land.Based on the collected data of each land,membership grade of each factor was obtained based on Fuzzy logic,and combined weight of each factor was got by analytica1 hierarch process and Delphi method.According to membership grades and combined weights of all factors,integrated fertility index(IFI)of every land was calculated to reflect levels of the productivity of reclamation lands in mining districts.Experimental results show that spatial information technique is an efficient method in field data collection,while lack of evaluation data.By means of quantificational analysis of this method,IFI is appropriate to describe the productive capacity level of reclamation lands.展开更多
The symbolization of land polygon is an important part of cartography.In the mapping of traditional present land-use maps,the symbol of land polygons was usually filled by the method of filling or plotting,but these m...The symbolization of land polygon is an important part of cartography.In the mapping of traditional present land-use maps,the symbol of land polygons was usually filled by the method of filling or plotting,but these methods can't solve the spatial conflicts of the symbol.According to the principle of cartography,the rule of how to symbolize the land polygon was summarized,and a new method that can generate and deploy the land symbols was presented.By making use of C#programming language and Arc Engine developing components,the algorithm can generate land symbols presenting triangle and adjust the coordinate of the symbol.Through mapping the present land-use map of Honghe county,this algorithm can reduce 88.84%of the spatial conflicts error rate compared with the traditional methods.It improves the accuracy and efficiency of the map symbolic.展开更多
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 in...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.展开更多
Tin is a critical metal for various industries,making its recovery from low-grade cassiterite ores crucial.This study aimed to optimize the flotation recovery of cassiterite using multi-component collector systems.Sev...Tin is a critical metal for various industries,making its recovery from low-grade cassiterite ores crucial.This study aimed to optimize the flotation recovery of cassiterite using multi-component collector systems.Several collectors were initially selected through micro-flotation tests,leading to the identification of optimal proportions for a four-component collector system(SHA-OHA-SPA-DBIA in a 4:3:2:1 ratio).Molecular dynamics simulations and surface tension tests were used to investigate the micellar behavior of these collectors in aqueous solution.The adsorption characteristics were quantified using microcalorimetry,enabling the determination of collection entropy and changes in Gibbs free energy.The four-component collector system showed the highest entropy change and the most favorable Gibbs free energy,leading to a cassiterite recovery of above 90%at a concentration of 8.0×10^(5)mol/L.Various analytical techniques were employed to systematically characterize the adsorption mechanism.The findings revealed a positive correlation between the adsorption products formed by the multicomponent collectors on the cassiterite surface and the entropy changes.Industrial-scale testing of the high-entropy collector system produced a tin concentrate with an Sn grade of 6.17%and an Sn recovery of 82.43%,demonstrating its substantial potential for practical applications in cassiterite flotation.展开更多
This study investigated the effect of konjac glucomannan(KGM)on the flotation separation of calcite and scheelite.Micro-flotation tests showed that under the action of 50 mg/L KGM,the floatability of calcite notably d...This study investigated the effect of konjac glucomannan(KGM)on the flotation separation of calcite and scheelite.Micro-flotation tests showed that under the action of 50 mg/L KGM,the floatability of calcite notably decreased,while the impact on scheelite was negligible,resulting in a recovery difference of 82.53%.Fourier transform infrared(FTIR)spectroscopy and atomic force micro-scopy(AFM)analyses indicated the selective adsorption of KGM on the calcite surface.Test results of the zeta potential and UV-visible absorption spectroscopy revealed that KGM prevented the adsorption of sodium oleate on the calcite surface.X-ray photoelectron spec-troscopy(XPS)analysis further confirmed the chemical adsorption of KGM on the calcite surface and the formation of Ca(OH)_(2).The density functional theory(DFT)simulation results were consistent with the flotation tests,demonstrating the strong adsorption perform-ance of KGM on the calcite surface.This study offers a pathway for highly sustainable and cost-effective mineral processing by utilizing the unique properties of biopolymers such as KGM to separate valuable minerals from gangue minerals.展开更多
Three types of activators such as sodium hydroxide,calcium oxide and triethanolamine(TEA)are used to establish different activation environments to address the problems associated with the process of activating fly as...Three types of activators such as sodium hydroxide,calcium oxide and triethanolamine(TEA)are used to establish different activation environments to address the problems associated with the process of activating fly ash paste.We conducted mechanical tests and numerical simulations to understand the evolution of microstructure,and used environmental scanning electron microscopy(ESEM)and energy dispersive spectroscopy(EDS)techniques to analyze the microenvironments of the samples.The mechanical properties of fly ash paste under different activation conditions and the changes in the microstructure and composition were investigated.The results revealed that under conditions of low NaOH content(1%-3%),the strength of the sample increased significantly.When the content exceeded 4%,the rate of increase in strength decreased.Based on the results,the optimal NaOH content was identified,which was about 4%.A good activation effect,especially for short-term activation(3-7 d),was achieved using TEA under high doping conditions.The activation effect was poor for long-term strength after 28 days.The CaO content did not significantly affect the degree of activation achieved.The maximum effect was exerted when the content of CaO was 2%.The virtual cement and concrete testing laboratory(VCCTL)was used to simulate the hydration process,and the results revealed that the use of the three types of activators accelerated the formation of Ca(OH)_(2) in the system.The activators also corroded the surface of the fly ash particles,resulting in a pozzolanic reaction.The active substances in fly ash were released efficiently,and hydration was realized.The pores were filled with hydration products,and the microstructure changed to form a new frame of paste filling that helped improve the strength of fly ash paste.展开更多
As one of the typical deposits in the Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province,the Daliangzi Pb-Zn deposit has a close genetic relationship with the structural system of the black/fracture zone formed under ...As one of the typical deposits in the Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province,the Daliangzi Pb-Zn deposit has a close genetic relationship with the structural system of the black/fracture zone formed under the action of the NWW-approximately EW strike-slip structures in the metallogenic province.The R1 black/fracture zone has a close relationship with ore forming;however,the mechanism of the rock-and ore-controlling action of the structural system remains unclear.Based on a detailed analysis of the tectonite-mineralized alteration lithofacies of the R1 black/fracture zone,the tectonite-mineralized alteration lithofacies zones can be divided into four types in succession outward from the Pb-Zn mineralization center(F_(5),F_(100),and other faults),i.e.,(1)the brecciated and stockwork-like Pb-Zn mineralization-complex breccia facies zone;(2)the stockwork-like Pb-Zn mineralization-simple breccia and cataclasite facies zone;(3)the veined pyrite-sulfide-dolomitic cataclasite facies zone;(4)the fine-veined calcite-black carbonized dolomite facies zone.With the evolution of the ore-forming fluid,the homogenization temperature decreases from Zone 1 to Zone 4;the salinity increases from Zone 1 to Zone 2 and then it decreases from Zones 3 and 4.The fluid density shows little change overall.The contents of Zn,Pb,Cu,Ga,Ge,Cd,Ag,and other metallogenic elements,Zn/Pb ratio,and CaO/MgO mole ratio decrease gradually from Zone 1 to Zone 4,and the REE fractionation,calcilization,silicification,and pyritization enhance gradually from Zone 1 to Zone 4.This series of changes is the product of diapirism(cryptoexplosion)of strike-slip structures and the black/fracture zone,among which the second-order structures derived from NWW-approximately EW-striking dextral shear-tension faults F_(1)and F_(15)control the brecciated and stockwork-like Pb-Zn mineralized complex breccia facies zones and the stockwork-like Pb-Zn mineralized simple breccia and cataclasite facies zones.Therefore,this paper establishes the zoning mode of tectonite-mineralized alteration lithofacies of the black/fracture zone and proposes that Zones 1 and 2 provide important prospecting criteria.展开更多
1.Objective.The Yidun arc within the Tethys-Himalaya metallogenic belt formed during the westward subduction of the Ganzi-Litang Ocean(237-206 Ma)during the Indosinian period,and then underwent the evolution stages of...1.Objective.The Yidun arc within the Tethys-Himalaya metallogenic belt formed during the westward subduction of the Ganzi-Litang Ocean(237-206 Ma)during the Indosinian period,and then underwent the evolution stages of the collisional orogeny(206-138 Ma)and the post-collisional orogeny(135-75 Ma).In recent years,a series of large and medium-sized Late Yanshanian intracontinental porphyry-skarn Mo-Cu-W deposits have been discovered in the southern part of the Yidun arc,including Xiuwacu,Relin,Hongshan,Tongchanggou,and Donglufang(Fig.1a).展开更多
Hemihydrate phosphogypsum(HPG)-based filling materials have become a new low-cost green alternative for early strength filling materials.They also provide a promising solution for the large-scale utilization of phosph...Hemihydrate phosphogypsum(HPG)-based filling materials have become a new low-cost green alternative for early strength filling materials.They also provide a promising solution for the large-scale utilization of phosphogypsum.However,pipe plugging,which is caused by the poor workability of HPG-based filling materials,has become a major safety hazard in the filling process.Determining an economical and practicable method is urgently needed to improve the workability of HPG slurry work.First,this work found that grind-ing treatment was much more effective than increasing concentration(59wt%-65wt%)and adding tailings(20wt%-100wt%)in enhan-cing the workability of HPG slurry based on a comprehensive analysis of water retention,fluidity,and flow stability.Then,the combined effects of particle size,particle morphology,water film,and interparticle interactions on the workability of HPG slurry were quantitat-ively described through a microanalysis.Moreover,the first direct evidence for the transformation from robust embedded structures to soft stacking structures was presented.In practice,the filling materials should be prepared by grinding HPG for 20 min and mixing with 0-200wt%phosphorus tailings to achieve satisfactory workability and mechanical performance.The results of this study provide practic-al and feasible methods for addressing the stable transportation problem of HPG slurry.展开更多
The middle-scale Heima zinnwaldite deposit is situated in the southeastern Tibetan Plateau,SW China.The NNW-to NS-trending orebodies are hosted in the Gaoligongshan metamorphic zone.To clarify the zinnwaldite genesis ...The middle-scale Heima zinnwaldite deposit is situated in the southeastern Tibetan Plateau,SW China.The NNW-to NS-trending orebodies are hosted in the Gaoligongshan metamorphic zone.To clarify the zinnwaldite genesis at Heima,this study presents an integrated investigation of the Heima pegmatites,combining precise geochronology,isotopic tracing,and detailed mineral chemistry to constrain its formation age,petrogenetic origin,and mineralization processes.Our robust geochronological framework,employing magmatic zircon(56.93±0.53 Ma)and cassiterite(57.0±4.2 Ma),establishes the pegmatite emplacement during the Late Paleocene to Early Eocene,representing the maximum age of lithium mineralization.Hf isotopic compositions(εHf_((t))=−14.3 to−12.4)demonstrate that the Heima pegmatite originated from remelting of ancient sediments,distinguishing it from contemporaneous Eocene Gangdese-Tengchong granites(εHf_((t))=−12.7 to+11.0)that show mantle contributions.This crustal signature aligns with the evolutionary trend of Hf isotopes in regional gneissic granites(600−420 Ma),supporting an anatectic origin from ancient continental crust rather than being derivatives of nearby Eocene granitic plutons.Detailed geochemical analysis of Li-micas reveals two distinct generations with contrasting formation mechanisms.The primary mica-Ia(53.45±0.86 Ma,Rb-Sr age)exhibits extreme incompatible element enrichment(Li,Be,Rb,Cs)and remarkably low K/Rb ratios(3.98-4.37),characteristic of crystallization from highly fractionated granitic melts.In contrast,secondary mica-Ib and mica-Ⅱ(17.9-16.0 Ma,Rb-Sr age)show significant Nb-Ta-W enrichment,reflecting precipitation from F-P-rich hydrothermal fluids during Miocene metamorphic-hydrothermal events.Principal component analysis(PCA)confirms the compositional disparity between these mica generations,with the later phases attributed to fluid-induced alteration and reworking.Regional correlation identifies two distinct lithium mineralization episodes in the Gongshan area,southeast Tibetan Plateau.The Eocene phase(~55 Ma)is zinnwaldite-dominant(e.g.,Heima,Puladi),associated with crustal melting following Neo-Tethyan closure.The Miocene phase(~17 Ma)is spodumene-dominant(e.g.,Danzhu,Peili),linked to Himalayan leucogranites formed as the rapid exhumation,denudation,and decompression partial melting of Himalayan Crystalline Complex.展开更多
The Gejiu tin-copper-(tungsten)(Sn-Cu-(W))polymetallic district is located in the southwest of the W-Sn metallogenic belt in the western Youjiang Basin,Yunnan,Southwest China.Abundant W minerals have been identified i...The Gejiu tin-copper-(tungsten)(Sn-Cu-(W))polymetallic district is located in the southwest of the W-Sn metallogenic belt in the western Youjiang Basin,Yunnan,Southwest China.Abundant W minerals have been identified in the region via exploration.However,metallogenic sources and evolution of W remain unclear,and the existing metallogenic model has to be updated to guide further ore prospecting.Elemental and Sr-Nd isotopic data for scheelites assist in the determination of sources and evolution of the W-mineralizing fluids and metals in the district.Based on field geological survey,the scheelites in the Gejiu district can be categorized into three types:altered granite(Type Ⅰ),quartz vein(Type Ⅱ)from the Laochang deposit,and skarn(Type Ⅲ)from the Kafang deposit.Types Ⅰ and Ⅱ scheelites have low molybdenum(Mo)and strontium(Sr)contents,and Type Ⅱ scheelite has lower Sr contents than Type Ⅰ as well as higher Mo and Sr contents than Type Ⅲ scheelites.Varying Mo contents across the scheelite types suggests that the oxygen fugacity varied during ore accumulation.Type Ⅰ and Type Ⅱ scheelites exhibit similar rare earth elements(REE)patterns;Type Ⅲ scheelite contains lower REE content,particularly HREE,compared with the other scheelites.All scheelites exhibit negative Eu anomalies in the chondrite-normalized REE patterns.As the W-mineralization and two-mica granite share close spatial and temporal relationships,the negative Eu anomalies were likely inherited from the two-mica granite.Type Ⅰ and Type Ⅱ scheelites display varied(^(87)Sr/^(86)Sr)_(82 Ma)(0.7090-0.7141)andε_(Nd)(82 Ma)(from−9.9 to−5.4)values,similar to those of granite.However,Type Ⅲ scheelite exhibits lower(^(87)Sr/^(86)Sr)_(82 Ma)(0.7083-0.7087)and lowerε_(Nd)(82 Ma)(from−10.5 to−6.9)values than the two-mica granite.This indicates that the two-mica granite alone did not provide the ore-forming fluids and metals and that the Type Ⅲ scheelite ore-forming fluids likely involved external fluids that were probably derived from carbonate rocks.The implication is that highly differentiated two-mica granites were the source of primary W-bearing metals and fluids,which is consistent with earlier research on the origin of Sn ore-forming materials.展开更多
To investigate the influence of different joint conditions on the rockburst of a circular tunnel,a true-triaxial test of rockburst with a single set of joint conditions was conducted.The rockburst incubation and evolu...To investigate the influence of different joint conditions on the rockburst of a circular tunnel,a true-triaxial test of rockburst with a single set of joint conditions was conducted.The rockburst incubation and evolution characteristics and acoustic emission evolution characteristics under different joint directions and joint dip angles were studied.The Weibull function was used to fit rockburst debris with different particle sizes and a single set of joints to obtain statistical results.The experimental results revealed that shear fracture rockburst occurred in samples with joints aligned with the tunnel strike as well as joints with inclination angles of 45°,60°,and 90°.Slab buckling–shear fracture rockburst was more likely to occur in samples with inclination angles of 0°and 30°.Slab buckling–shear fracture rockburst occurred in samples with joints crossing the tunnel strike as well as in samples with joints with inclination angles of 0°,30°,45°,60°,and 90°.The location of the rockburst pit was influenced by the joint inclination angle when the joints aligned with the tunnel strike.In contrast,when the joints crossed the tunnel strike,the location of the rockburst pit was independent of the joint inclination angle.The cumulative absolute energy of acoustic emission(AE)exhibited an overall upward trend with the increase in joint dip angle.The cumulative absolute energy of the AE of the jointed samples was greater than that of intact samples(without joints).Loading reached the rockburst stage in the samples with joints aligned with the tunnel strike and dip angles of 45°,60°,and 90°.Moreover,the peak value of AE cumulative absolute energy was the highest.These results can elucidate the evolution mechanism of rockburst in the surrounding rock of circular tunnels with a single set of joints in deep underground engineering.展开更多
In response to the three major contradictions,safety,cognition,and ability cultivation,existing in the practical teaching of geological hazard courses,this paper proposes a“virtual-real integration”teaching reform s...In response to the three major contradictions,safety,cognition,and ability cultivation,existing in the practical teaching of geological hazard courses,this paper proposes a“virtual-real integration”teaching reform scheme,using earthquake disasters as an example.By integrating digital twin technology and artificial intelligence technology,a four-layer teaching framework consisting of data layer,model layer,platform layer,and intelligent layer is constructed.Progressive teaching segments of“cognition-simulation-decision-making”are designed to establish a comprehensive training path from seismic geological survey to disaster early warning and decision-making.This scheme shifts the traditional field practice venue to a safe virtual environment,promotes students’understanding of geological hazards from static fragments to dynamic processes,enhances their comprehensive decision-making ability in geological disaster prevention and mitigation,and provides theoretical support and practical guidance for cultivating interdisciplinary talents in geological hazard prevention.展开更多
Flotation behavior of stibiconite after sulfidation roasting with sulfur at a high temperature and the sulfidation mechanisms were investigated by ultraviolet spectrophotometry,X-ray diffraction(XRD)combining with the...Flotation behavior of stibiconite after sulfidation roasting with sulfur at a high temperature and the sulfidation mechanisms were investigated by ultraviolet spectrophotometry,X-ray diffraction(XRD)combining with thermodynamic calculation,X-ray photoelectron spectroscopy(XPS)and electron probe microanalysis(EPMA).The XRD and thermodynamic analyses revealed that the Sb_(3)O_(6)(OH)was reduced into Sb_(2)O_(4)and Sb_(2)O_(3),and was transformed into Sb_(2)S_(3)after introducing sulfur at high temperatures.Flotation test results show that flotation recovery of the stibiconite after sulfidation reaches 90.3%.Ultraviolet spectrophotometry tests confirm that adsorption capacity of sodium butyl xanthate(SBX)on surface of the roasted products has a positive relationship with S/Sb mole ratio.XPS analyses indicate that Sb-bearing species including mainly Sb_(2)S_(3),Sb_(2)O_(3)and Sb_(2)(SO_(4))_(3) are formed at the surface of particle after sulfidation.The EPMA analyses verify that the Sb_(2)S_(3)is generated at the outer layer of sample after sulfidation roasting,but the particle interior is mainly composed of antimony oxides.The sulfur atmosphere induces the outward migration of oxygen to form Sb_(2)O_(4).Then,the Sb_(2)O_(4)is transformed into Sb_(2)O_(3)in two pathways,and the Sb_(2)S_(3)is formed.These findings will provide theoretical support for recovering antimony from antimony oxide ores by xanthate flotation methods.展开更多
The western margin of the Yangtze Block hosts diverse Neoproterozoic igneous rocks,with exposed S-type granites serving as key indicators for deciphering regional geological evolution.This study focuses on the Jiudaow...The western margin of the Yangtze Block hosts diverse Neoproterozoic igneous rocks,with exposed S-type granites serving as key indicators for deciphering regional geological evolution.This study focuses on the Jiudaowan granite pluton,located on the western margin of the Yangtze Block,through systematic petrographic,whole-rock geochemical,zircon and monazite U-Pb geochronology,and whole-rock Nd isotopic analyses aiming to elucidate its petrogenesis and tectonic significance.The Jiudaowan granite pluton is a composite body,consisting of the Luotaijiu,Jiudaowan,and Daheishan units,characterized by biotite monzogranites,muscovite-plagioclase granites,and two-mica monzogranites,respectively.LA-ICP-MS zircon and monazite U-Pb dating reveals crystallization ages between 832 and 798 Ma.The three units are peraluminous,containing minerals such as muscovite,garnet,and tourma-line,and exhibiting high SiO_(2)(72.99-77.83 wt%),Al_(2)O_(3)(12.36-15.02 wt%),and A/CNK values(1.06-1.43),con-firming their classification as peraluminous S-type granites.Compositional variations within the Jiudaowan granite pluton are primarily controlled by protolith composition and melting mechanisms.The pluton is distinguished by low CaO/Na_(2)O ratios(0.02-0.18),high Rb/Sr(0.83-113)and Rb/Ba(0.33-15.2)ratios,and negativeεNd(t)values(−13.6 to−9.1),indicating derivation from partial melting of het-erogeneous metasedimentary sources.MgO,TiO_(2),Rb/Sr,and whole-rock Zr saturation temperatures suggest that the Luotaijiu and Daheishan units formed via biotite dehydration melting,whereas the Jiudaowan unit resulted from muscovite dehydration melting.Additionally,the Jiudaowan granite pluton displays a clear negative correlation between Al_(2)O_(3),CaO,Fe_(2)O_(3)T,MgO,TiO_(2),and SiO_(2),along with pronounced Eu negative anomalies and depletions in Sr and Ti,suggesting fractional crystallization of feldspar,mica,and Fe-Ti oxides during magma emplacement.Similarly,variable incompatible element ratios of Nb/U(1.07-18.97)and Nb/La(0.24-26.88)further indicate minor crustal assimilation and contamination during magma evolution.Integrating regional geological data,we propose that the Jiudaowan pluton formed during crustal thickening associated with post-collisional extension,likely related to the breakup of the Rodinia supercontinent.展开更多
The Saxi tungsten deposit,located in the Laojunshan ore district of southeastern Yunnan Province,is a significant W-polymetallic deposit.The origins of tungstenbearing pegmatite dikes and quartz vein mineralization in...The Saxi tungsten deposit,located in the Laojunshan ore district of southeastern Yunnan Province,is a significant W-polymetallic deposit.The origins of tungstenbearing pegmatite dikes and quartz vein mineralization in the Saxi deposit remain poorly understood.This study employs in situ U-Pb dating of apatite from the altered granite,along with trace element and S-Pb isotopic analysis of arsenopyrite,to investigate the timing,source of ore-forming fluids and the mechanisms of tungsten enrichment.The apatite in the altered granite yields a U-Pb age of 147.0±4.0 Ma,indicating magmatic activity during the Early Cretaceous.Three generations of arsenopyrite(Apy)are identified:Apy-1 in the altered granite,Apy-2 in the pegmatite dikes and Apy-3 in the quartz veins.The S/Fe ratios for Apy-1,Apy-2 and Apy-3 range from 0.98 to 1.09,0.89 to 0.92 and 0.86 to 1.02,respectively(average 0.97),suggesting a magmatic-hydrothermal origin.Sulfur isotope values(δ^(34)S=4.29‰-8.11‰)indicate that it was likely sourced from deep magmatic-hydrothermal fluids.Lead isotopic compositions of arsenopyrite suggest that the granitic parental magma is derived from the upper crust.These findings point to a magmatic-hydrothermal origin for the vein-type tungsten mineralization,linked to a concealed magmatichydrothermal system in the Early Cretaceous.展开更多
The migration mechanisms of ore-forming fluids have long been a focus in the field of ore deposit studies.Calcite is ubiquitously present in various types of rocks in the lithosphere,and the underlying mechanisms of i...The migration mechanisms of ore-forming fluids have long been a focus in the field of ore deposit studies.Calcite is ubiquitously present in various types of rocks in the lithosphere,and the underlying mechanisms of its influence on fluid migration are of crucial importance.While previous studies have revealed that salinity changes can modulate fluid migration,the underlying mechanisms remain poorly understood.We employ molecular dynamics simulations to elucidate how salinity variations in ore-forming fluids modulate the adsorption onto calcite nanopore walls,thereby revealing the microscopic mechanisms governing ore fluid transport through calcite nano-fractures.The results show that the adsorption energy Eint of the solution on the calcite surface increased from -14,948.84±182.48 kcal/mol to -12,144.08±118.2 kcal/mol as salinity increased,which is conducive to the long-range transport of the fluid in the calcite nanopore.展开更多
基金supported by the project of the National Natural Science Foundation of China entitled“Distribution and change characteristics of construction land on slope gradient in mountainous cities of southern China”(No.41961039)。
文摘China's requisition-compensation balance strategy has dramatically reshaped cropland spatial patterns,drawing multidisciplinary research attention.However,existing studies predominantly emphasize horizontal distribution,overlooking the significant influence of slope gradient on cropland spatial patterns.This paper proposes a slope location quotient(SLQ)index that reflects the relative advantage of cropland distribution and explores the slope grade difference of cropland spatial patterns in China at the county scale.The analysis adopts 30-m resolution digital elevation model with land cover data,taking 2672 counties with cropland ratio>1%as study units.The temporal scope covers 1990 and 2020,with slope gradients categorized into five grades:0°~2°,2°~6°,6°~15°,15°~25°,and 25°~90°.Results show that:1)The inverse correlation between cropland area and slope gradient remained stable throughout the study period,with the variation in cropland area frequency across slope grades being less than 1%.2)The spatial patterns of SLQ in 1990 and 2020 both transited stepwise with slope gradient,while≤2°and>6°slopes exhibited opposing patterns.3)The mean absolute variation of SLQ during 1990-2020 increased with slope gradient(R2=0.926,p<0.01).Particularly for slope grades>15°,the mean absolute variation reached 0.26(for 15°~25°)and 0.43(for 25°~90°),respectively,and displayed a distinct southward-increasing and northwarddecreasing pattern.This study offers novel slopegradient perspectives for analyzing cropland spatial patterns.To enhance cropland protection benefits,reversing the steep cropland SLQ surge in southern China is recommended.
基金financially supported by the Excellent Youth Scholars Program of State Key Laboratory of Complex Nonferrous Metal Resource Clean Utilization,Kunming University of Science and Technology,China(No.YXQN-2024003)the Central Government-Guided Local Science and Technology Development Fund Project,China(No.202407AB110022)。
文摘The rapid advancement of modern science and technology,coupled with the recent surge in new-energy electric vehicles,has significantly boosted the demand for lithium.This has promoted the development and efficient utilization of lepidolite as a lithium source.Therefore,the processes for the flotation of lepidolite have been studied in depth,particularly the development and use of lepidolite flotation collectors and the action mechanism of the collectors on the lepidolite surface.Based on the crystal-structure characteristics of lepidolite minerals,this review focuses on the application of anionic collectors,amine cationic collectors(primary amines,quaternary ammonium salts,ether amines,and Gemini amines),and combined collectors to the flotation behavior of lepidolite as well as the adsorption mechanisms.New directions and technologies for the controllable flotation of lepidolite are proposed,including process improvement,reagent synthesis,and mechanistic research.This analysis demonstrates the need for the further study of the complex environment inside lepidolite and pulp.By using modern analytical detection methods and quantum chemical calculations,research on reagents for the flotation of lepidolite has expanded,providing new concepts and references for the efficient flotation recovery and utilization of lepidolite.
文摘The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with GPS field collected data in the area of Xiaowan-Dachaoshan Reservoirs of Lancangjiang River cascaded Hydropower Area. Consequently, the land-cover is divided into five subclasses, namely water, paddy field and wetland, bare dryland and sparse shrub, secondary forest and density forest. The result showed that the areas of bare land, upland and secondary forest decreased in 1988-1996, whereas from 1996 to 2000, water body and density forest keep invariability while the areas of paddy field and wetland, bare dryland and sparse scrub increasing and the area of secondary forest decrease; Features of reciprocal transformation between density forest and other type of land-cover had two points, i.e. secondary forest, bare dryland and sparse shrub converted to density forest; and density forest converted to secondary forest and paddy field and wetland. It reflects the dynamic variation of density forest; the area which slope less than 8° and greater than 15° shows bigger variation, however, less change in 8°-15°.
基金Project(41061043)supported by the National Natural Science Foundation of ChinaProject(2010CD032)supported by the Natural Science Foundation of Yunnan Province,China
文摘In order to evaluate the productivity of reclamation lands in mining districts,field investigation and spatial information technique were adopted to investigate influence factors of land.Based on the collected data of each land,membership grade of each factor was obtained based on Fuzzy logic,and combined weight of each factor was got by analytica1 hierarch process and Delphi method.According to membership grades and combined weights of all factors,integrated fertility index(IFI)of every land was calculated to reflect levels of the productivity of reclamation lands in mining districts.Experimental results show that spatial information technique is an efficient method in field data collection,while lack of evaluation data.By means of quantificational analysis of this method,IFI is appropriate to describe the productive capacity level of reclamation lands.
基金Project(41061043)support by the National Natural Science Foundation of China
文摘The symbolization of land polygon is an important part of cartography.In the mapping of traditional present land-use maps,the symbol of land polygons was usually filled by the method of filling or plotting,but these methods can't solve the spatial conflicts of the symbol.According to the principle of cartography,the rule of how to symbolize the land polygon was summarized,and a new method that can generate and deploy the land symbols was presented.By making use of C#programming language and Arc Engine developing components,the algorithm can generate land symbols presenting triangle and adjust the coordinate of the symbol.Through mapping the present land-use map of Honghe county,this algorithm can reduce 88.84%of the spatial conflicts error rate compared with the traditional methods.It improves the accuracy and efficiency of the map symbolic.
基金supported by Fundamental Research Projects of Yunnan Province,China(Nos.202101BE070001-009,202301AU070189).
文摘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.
基金supported by Yunnan Science and Technology Leading Talent Project(No.202305AB350005)。
文摘Tin is a critical metal for various industries,making its recovery from low-grade cassiterite ores crucial.This study aimed to optimize the flotation recovery of cassiterite using multi-component collector systems.Several collectors were initially selected through micro-flotation tests,leading to the identification of optimal proportions for a four-component collector system(SHA-OHA-SPA-DBIA in a 4:3:2:1 ratio).Molecular dynamics simulations and surface tension tests were used to investigate the micellar behavior of these collectors in aqueous solution.The adsorption characteristics were quantified using microcalorimetry,enabling the determination of collection entropy and changes in Gibbs free energy.The four-component collector system showed the highest entropy change and the most favorable Gibbs free energy,leading to a cassiterite recovery of above 90%at a concentration of 8.0×10^(5)mol/L.Various analytical techniques were employed to systematically characterize the adsorption mechanism.The findings revealed a positive correlation between the adsorption products formed by the multicomponent collectors on the cassiterite surface and the entropy changes.Industrial-scale testing of the high-entropy collector system produced a tin concentrate with an Sn grade of 6.17%and an Sn recovery of 82.43%,demonstrating its substantial potential for practical applications in cassiterite flotation.
基金supported by the National Natural Science Foundation of China(No.52164022).
文摘This study investigated the effect of konjac glucomannan(KGM)on the flotation separation of calcite and scheelite.Micro-flotation tests showed that under the action of 50 mg/L KGM,the floatability of calcite notably decreased,while the impact on scheelite was negligible,resulting in a recovery difference of 82.53%.Fourier transform infrared(FTIR)spectroscopy and atomic force micro-scopy(AFM)analyses indicated the selective adsorption of KGM on the calcite surface.Test results of the zeta potential and UV-visible absorption spectroscopy revealed that KGM prevented the adsorption of sodium oleate on the calcite surface.X-ray photoelectron spec-troscopy(XPS)analysis further confirmed the chemical adsorption of KGM on the calcite surface and the formation of Ca(OH)_(2).The density functional theory(DFT)simulation results were consistent with the flotation tests,demonstrating the strong adsorption perform-ance of KGM on the calcite surface.This study offers a pathway for highly sustainable and cost-effective mineral processing by utilizing the unique properties of biopolymers such as KGM to separate valuable minerals from gangue minerals.
基金Supported by Yunnan Major Scientific and Technological Projects(No.202403AA080001)National Natural Science Foundation of China(No.52074137)Yunnan Fundamental Research Projects(No.202201AT070151)。
文摘Three types of activators such as sodium hydroxide,calcium oxide and triethanolamine(TEA)are used to establish different activation environments to address the problems associated with the process of activating fly ash paste.We conducted mechanical tests and numerical simulations to understand the evolution of microstructure,and used environmental scanning electron microscopy(ESEM)and energy dispersive spectroscopy(EDS)techniques to analyze the microenvironments of the samples.The mechanical properties of fly ash paste under different activation conditions and the changes in the microstructure and composition were investigated.The results revealed that under conditions of low NaOH content(1%-3%),the strength of the sample increased significantly.When the content exceeded 4%,the rate of increase in strength decreased.Based on the results,the optimal NaOH content was identified,which was about 4%.A good activation effect,especially for short-term activation(3-7 d),was achieved using TEA under high doping conditions.The activation effect was poor for long-term strength after 28 days.The CaO content did not significantly affect the degree of activation achieved.The maximum effect was exerted when the content of CaO was 2%.The virtual cement and concrete testing laboratory(VCCTL)was used to simulate the hydration process,and the results revealed that the use of the three types of activators accelerated the formation of Ca(OH)_(2) in the system.The activators also corroded the surface of the fly ash particles,resulting in a pozzolanic reaction.The active substances in fly ash were released efficiently,and hydration was realized.The pores were filled with hydration products,and the microstructure changed to form a new frame of paste filling that helped improve the strength of fly ash paste.
基金funded by the programs of the National Natural Science Foundation(Nos.42172086,41572060,U1133602)the Program of‘Yunling Scholar’of Yunnan province(2014)+1 种基金the Projects of the Yunnan Engineering Laboratory of Mineral Resources Prediction and Evaluation(YM Lab)(2010)the Innovation Team of Yunnan Province and KMUST(2008,2012).
文摘As one of the typical deposits in the Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province,the Daliangzi Pb-Zn deposit has a close genetic relationship with the structural system of the black/fracture zone formed under the action of the NWW-approximately EW strike-slip structures in the metallogenic province.The R1 black/fracture zone has a close relationship with ore forming;however,the mechanism of the rock-and ore-controlling action of the structural system remains unclear.Based on a detailed analysis of the tectonite-mineralized alteration lithofacies of the R1 black/fracture zone,the tectonite-mineralized alteration lithofacies zones can be divided into four types in succession outward from the Pb-Zn mineralization center(F_(5),F_(100),and other faults),i.e.,(1)the brecciated and stockwork-like Pb-Zn mineralization-complex breccia facies zone;(2)the stockwork-like Pb-Zn mineralization-simple breccia and cataclasite facies zone;(3)the veined pyrite-sulfide-dolomitic cataclasite facies zone;(4)the fine-veined calcite-black carbonized dolomite facies zone.With the evolution of the ore-forming fluid,the homogenization temperature decreases from Zone 1 to Zone 4;the salinity increases from Zone 1 to Zone 2 and then it decreases from Zones 3 and 4.The fluid density shows little change overall.The contents of Zn,Pb,Cu,Ga,Ge,Cd,Ag,and other metallogenic elements,Zn/Pb ratio,and CaO/MgO mole ratio decrease gradually from Zone 1 to Zone 4,and the REE fractionation,calcilization,silicification,and pyritization enhance gradually from Zone 1 to Zone 4.This series of changes is the product of diapirism(cryptoexplosion)of strike-slip structures and the black/fracture zone,among which the second-order structures derived from NWW-approximately EW-striking dextral shear-tension faults F_(1)and F_(15)control the brecciated and stockwork-like Pb-Zn mineralized complex breccia facies zones and the stockwork-like Pb-Zn mineralized simple breccia and cataclasite facies zones.Therefore,this paper establishes the zoning mode of tectonite-mineralized alteration lithofacies of the black/fracture zone and proposes that Zones 1 and 2 provide important prospecting criteria.
基金jointly supported by the Selection Project of High-level Scientific and Technological Talents and Innovative Teams Project in Yunnan Province(202305AT350004-4)the National Natural Science Foundation of China(42362010 and 42464005)+3 种基金the Field Scientific Observation and Research Station of Mountain Agroecosystem in the Lower Reaches of Nujiang River,Yunnan Province(202305AM340031)the Yunnan Provincial Department of Education Science Research Fund Project(2025J0983)the Wen Bang-chun Academician Workstation in Yunnan Province(202205AF150032)the Undergraduate Innovative Training Program(2310603235).
文摘1.Objective.The Yidun arc within the Tethys-Himalaya metallogenic belt formed during the westward subduction of the Ganzi-Litang Ocean(237-206 Ma)during the Indosinian period,and then underwent the evolution stages of the collisional orogeny(206-138 Ma)and the post-collisional orogeny(135-75 Ma).In recent years,a series of large and medium-sized Late Yanshanian intracontinental porphyry-skarn Mo-Cu-W deposits have been discovered in the southern part of the Yidun arc,including Xiuwacu,Relin,Hongshan,Tongchanggou,and Donglufang(Fig.1a).
基金financial support from the National Natural Science Foundation of China(No.52074137)the Yunnan Fundamental Research Projects,China(Nos.202301BE070001-054 and 202401CF070124)the Yunnan Major Scientific and Technological Projects,China(No.202403AA080001).
文摘Hemihydrate phosphogypsum(HPG)-based filling materials have become a new low-cost green alternative for early strength filling materials.They also provide a promising solution for the large-scale utilization of phosphogypsum.However,pipe plugging,which is caused by the poor workability of HPG-based filling materials,has become a major safety hazard in the filling process.Determining an economical and practicable method is urgently needed to improve the workability of HPG slurry work.First,this work found that grind-ing treatment was much more effective than increasing concentration(59wt%-65wt%)and adding tailings(20wt%-100wt%)in enhan-cing the workability of HPG slurry based on a comprehensive analysis of water retention,fluidity,and flow stability.Then,the combined effects of particle size,particle morphology,water film,and interparticle interactions on the workability of HPG slurry were quantitat-ively described through a microanalysis.Moreover,the first direct evidence for the transformation from robust embedded structures to soft stacking structures was presented.In practice,the filling materials should be prepared by grinding HPG for 20 min and mixing with 0-200wt%phosphorus tailings to achieve satisfactory workability and mechanical performance.The results of this study provide practic-al and feasible methods for addressing the stable transportation problem of HPG slurry.
基金supported by the Ministry of Natural Resources-Provincial Joint Cooperation Project in 2024(No.2024ZRBSHZ126)The Second Comprehensive Scientific Research Project on the Qinghai-Tibetan Plateau“Assessment of Current Status and Future Prospects for Rare Metal Resources”(No.2019QZKK0802)+4 种基金Yunnan Foundation Project(No.202201AU070162)Career Development Fund for Early-Career Geologists at YIGS(No.YDKYR[2024]3)YDIG Expert Innovation Studio(No.YDIG[2024]24)New round of Yunnan Province prospecting Action and Project of Geological Exploration Fund(No.K202408)KUST-NSRF Talent Development Project(No.KKZ3202421133).
文摘The middle-scale Heima zinnwaldite deposit is situated in the southeastern Tibetan Plateau,SW China.The NNW-to NS-trending orebodies are hosted in the Gaoligongshan metamorphic zone.To clarify the zinnwaldite genesis at Heima,this study presents an integrated investigation of the Heima pegmatites,combining precise geochronology,isotopic tracing,and detailed mineral chemistry to constrain its formation age,petrogenetic origin,and mineralization processes.Our robust geochronological framework,employing magmatic zircon(56.93±0.53 Ma)and cassiterite(57.0±4.2 Ma),establishes the pegmatite emplacement during the Late Paleocene to Early Eocene,representing the maximum age of lithium mineralization.Hf isotopic compositions(εHf_((t))=−14.3 to−12.4)demonstrate that the Heima pegmatite originated from remelting of ancient sediments,distinguishing it from contemporaneous Eocene Gangdese-Tengchong granites(εHf_((t))=−12.7 to+11.0)that show mantle contributions.This crustal signature aligns with the evolutionary trend of Hf isotopes in regional gneissic granites(600−420 Ma),supporting an anatectic origin from ancient continental crust rather than being derivatives of nearby Eocene granitic plutons.Detailed geochemical analysis of Li-micas reveals two distinct generations with contrasting formation mechanisms.The primary mica-Ia(53.45±0.86 Ma,Rb-Sr age)exhibits extreme incompatible element enrichment(Li,Be,Rb,Cs)and remarkably low K/Rb ratios(3.98-4.37),characteristic of crystallization from highly fractionated granitic melts.In contrast,secondary mica-Ib and mica-Ⅱ(17.9-16.0 Ma,Rb-Sr age)show significant Nb-Ta-W enrichment,reflecting precipitation from F-P-rich hydrothermal fluids during Miocene metamorphic-hydrothermal events.Principal component analysis(PCA)confirms the compositional disparity between these mica generations,with the later phases attributed to fluid-induced alteration and reworking.Regional correlation identifies two distinct lithium mineralization episodes in the Gongshan area,southeast Tibetan Plateau.The Eocene phase(~55 Ma)is zinnwaldite-dominant(e.g.,Heima,Puladi),associated with crustal melting following Neo-Tethyan closure.The Miocene phase(~17 Ma)is spodumene-dominant(e.g.,Danzhu,Peili),linked to Himalayan leucogranites formed as the rapid exhumation,denudation,and decompression partial melting of Himalayan Crystalline Complex.
基金financed by Yunnan Major Scientific and Technological Projects(Grant No.202202AG050006)the National Natural Science Foundation of China(Grant No.42462011)Projects of Yunnan Province Technology Hall(Grant No.202305AT350004).
文摘The Gejiu tin-copper-(tungsten)(Sn-Cu-(W))polymetallic district is located in the southwest of the W-Sn metallogenic belt in the western Youjiang Basin,Yunnan,Southwest China.Abundant W minerals have been identified in the region via exploration.However,metallogenic sources and evolution of W remain unclear,and the existing metallogenic model has to be updated to guide further ore prospecting.Elemental and Sr-Nd isotopic data for scheelites assist in the determination of sources and evolution of the W-mineralizing fluids and metals in the district.Based on field geological survey,the scheelites in the Gejiu district can be categorized into three types:altered granite(Type Ⅰ),quartz vein(Type Ⅱ)from the Laochang deposit,and skarn(Type Ⅲ)from the Kafang deposit.Types Ⅰ and Ⅱ scheelites have low molybdenum(Mo)and strontium(Sr)contents,and Type Ⅱ scheelite has lower Sr contents than Type Ⅰ as well as higher Mo and Sr contents than Type Ⅲ scheelites.Varying Mo contents across the scheelite types suggests that the oxygen fugacity varied during ore accumulation.Type Ⅰ and Type Ⅱ scheelites exhibit similar rare earth elements(REE)patterns;Type Ⅲ scheelite contains lower REE content,particularly HREE,compared with the other scheelites.All scheelites exhibit negative Eu anomalies in the chondrite-normalized REE patterns.As the W-mineralization and two-mica granite share close spatial and temporal relationships,the negative Eu anomalies were likely inherited from the two-mica granite.Type Ⅰ and Type Ⅱ scheelites display varied(^(87)Sr/^(86)Sr)_(82 Ma)(0.7090-0.7141)andε_(Nd)(82 Ma)(from−9.9 to−5.4)values,similar to those of granite.However,Type Ⅲ scheelite exhibits lower(^(87)Sr/^(86)Sr)_(82 Ma)(0.7083-0.7087)and lowerε_(Nd)(82 Ma)(from−10.5 to−6.9)values than the two-mica granite.This indicates that the two-mica granite alone did not provide the ore-forming fluids and metals and that the Type Ⅲ scheelite ore-forming fluids likely involved external fluids that were probably derived from carbonate rocks.The implication is that highly differentiated two-mica granites were the source of primary W-bearing metals and fluids,which is consistent with earlier research on the origin of Sn ore-forming materials.
基金funded by the National Natural Science Foundation of China(Grant Nos.52364005,51934003)Yunnan major scientific and technological special project(202202AG050014).This support is gratefully acknowledged.
文摘To investigate the influence of different joint conditions on the rockburst of a circular tunnel,a true-triaxial test of rockburst with a single set of joint conditions was conducted.The rockburst incubation and evolution characteristics and acoustic emission evolution characteristics under different joint directions and joint dip angles were studied.The Weibull function was used to fit rockburst debris with different particle sizes and a single set of joints to obtain statistical results.The experimental results revealed that shear fracture rockburst occurred in samples with joints aligned with the tunnel strike as well as joints with inclination angles of 45°,60°,and 90°.Slab buckling–shear fracture rockburst was more likely to occur in samples with inclination angles of 0°and 30°.Slab buckling–shear fracture rockburst occurred in samples with joints crossing the tunnel strike as well as in samples with joints with inclination angles of 0°,30°,45°,60°,and 90°.The location of the rockburst pit was influenced by the joint inclination angle when the joints aligned with the tunnel strike.In contrast,when the joints crossed the tunnel strike,the location of the rockburst pit was independent of the joint inclination angle.The cumulative absolute energy of acoustic emission(AE)exhibited an overall upward trend with the increase in joint dip angle.The cumulative absolute energy of the AE of the jointed samples was greater than that of intact samples(without joints).Loading reached the rockburst stage in the samples with joints aligned with the tunnel strike and dip angles of 45°,60°,and 90°.Moreover,the peak value of AE cumulative absolute energy was the highest.These results can elucidate the evolution mechanism of rockburst in the surrounding rock of circular tunnels with a single set of joints in deep underground engineering.
基金supported by Kunming University of Science and Technology 2024 graduate course ideological and political case construction project(109920240103)Case construction project of AI-enabled postgraduate talent training in Kunming University of Technology,the Yunnan Fundamental Research Projects(202501AT070358 and 202401AU070142)+1 种基金the Scientific Research Fund Program of Yunnan Provincial Department of Education(2024J0078)Talent Cultivation Fund Project of Kunming University of Science and Technology(KKZ3202467041 and KKZ3202467045).
文摘In response to the three major contradictions,safety,cognition,and ability cultivation,existing in the practical teaching of geological hazard courses,this paper proposes a“virtual-real integration”teaching reform scheme,using earthquake disasters as an example.By integrating digital twin technology and artificial intelligence technology,a four-layer teaching framework consisting of data layer,model layer,platform layer,and intelligent layer is constructed.Progressive teaching segments of“cognition-simulation-decision-making”are designed to establish a comprehensive training path from seismic geological survey to disaster early warning and decision-making.This scheme shifts the traditional field practice venue to a safe virtual environment,promotes students’understanding of geological hazards from static fragments to dynamic processes,enhances their comprehensive decision-making ability in geological disaster prevention and mitigation,and provides theoretical support and practical guidance for cultivating interdisciplinary talents in geological hazard prevention.
基金Projects(52074139,51964027)supported by the National Natural Science Foundation of ChinaProject(KKS 2202152011)supported by the High-level Talents of Yunnan Province,China。
文摘Flotation behavior of stibiconite after sulfidation roasting with sulfur at a high temperature and the sulfidation mechanisms were investigated by ultraviolet spectrophotometry,X-ray diffraction(XRD)combining with thermodynamic calculation,X-ray photoelectron spectroscopy(XPS)and electron probe microanalysis(EPMA).The XRD and thermodynamic analyses revealed that the Sb_(3)O_(6)(OH)was reduced into Sb_(2)O_(4)and Sb_(2)O_(3),and was transformed into Sb_(2)S_(3)after introducing sulfur at high temperatures.Flotation test results show that flotation recovery of the stibiconite after sulfidation reaches 90.3%.Ultraviolet spectrophotometry tests confirm that adsorption capacity of sodium butyl xanthate(SBX)on surface of the roasted products has a positive relationship with S/Sb mole ratio.XPS analyses indicate that Sb-bearing species including mainly Sb_(2)S_(3),Sb_(2)O_(3)and Sb_(2)(SO_(4))_(3) are formed at the surface of particle after sulfidation.The EPMA analyses verify that the Sb_(2)S_(3)is generated at the outer layer of sample after sulfidation roasting,but the particle interior is mainly composed of antimony oxides.The sulfur atmosphere induces the outward migration of oxygen to form Sb_(2)O_(4).Then,the Sb_(2)O_(4)is transformed into Sb_(2)O_(3)in two pathways,and the Sb_(2)S_(3)is formed.These findings will provide theoretical support for recovering antimony from antimony oxide ores by xanthate flotation methods.
基金supported by the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(Grant No.2024ZD1001600)National Natural Science Foundation of China(Grants Nos.42302223,42162012 and 42402069)Yunnan Fundamental Research Projects(Grants No.202401CF070093).
文摘The western margin of the Yangtze Block hosts diverse Neoproterozoic igneous rocks,with exposed S-type granites serving as key indicators for deciphering regional geological evolution.This study focuses on the Jiudaowan granite pluton,located on the western margin of the Yangtze Block,through systematic petrographic,whole-rock geochemical,zircon and monazite U-Pb geochronology,and whole-rock Nd isotopic analyses aiming to elucidate its petrogenesis and tectonic significance.The Jiudaowan granite pluton is a composite body,consisting of the Luotaijiu,Jiudaowan,and Daheishan units,characterized by biotite monzogranites,muscovite-plagioclase granites,and two-mica monzogranites,respectively.LA-ICP-MS zircon and monazite U-Pb dating reveals crystallization ages between 832 and 798 Ma.The three units are peraluminous,containing minerals such as muscovite,garnet,and tourma-line,and exhibiting high SiO_(2)(72.99-77.83 wt%),Al_(2)O_(3)(12.36-15.02 wt%),and A/CNK values(1.06-1.43),con-firming their classification as peraluminous S-type granites.Compositional variations within the Jiudaowan granite pluton are primarily controlled by protolith composition and melting mechanisms.The pluton is distinguished by low CaO/Na_(2)O ratios(0.02-0.18),high Rb/Sr(0.83-113)and Rb/Ba(0.33-15.2)ratios,and negativeεNd(t)values(−13.6 to−9.1),indicating derivation from partial melting of het-erogeneous metasedimentary sources.MgO,TiO_(2),Rb/Sr,and whole-rock Zr saturation temperatures suggest that the Luotaijiu and Daheishan units formed via biotite dehydration melting,whereas the Jiudaowan unit resulted from muscovite dehydration melting.Additionally,the Jiudaowan granite pluton displays a clear negative correlation between Al_(2)O_(3),CaO,Fe_(2)O_(3)T,MgO,TiO_(2),and SiO_(2),along with pronounced Eu negative anomalies and depletions in Sr and Ti,suggesting fractional crystallization of feldspar,mica,and Fe-Ti oxides during magma emplacement.Similarly,variable incompatible element ratios of Nb/U(1.07-18.97)and Nb/La(0.24-26.88)further indicate minor crustal assimilation and contamination during magma evolution.Integrating regional geological data,we propose that the Jiudaowan pluton formed during crustal thickening associated with post-collisional extension,likely related to the breakup of the Rodinia supercontinent.
基金Yunnan Major Scientific and Technological Project(grant no.202202AG050006)National Natural Science Foundation project(grant No.42272078)Yunnan Fundamental Research Project(grant No.202401CF070094).
文摘The Saxi tungsten deposit,located in the Laojunshan ore district of southeastern Yunnan Province,is a significant W-polymetallic deposit.The origins of tungstenbearing pegmatite dikes and quartz vein mineralization in the Saxi deposit remain poorly understood.This study employs in situ U-Pb dating of apatite from the altered granite,along with trace element and S-Pb isotopic analysis of arsenopyrite,to investigate the timing,source of ore-forming fluids and the mechanisms of tungsten enrichment.The apatite in the altered granite yields a U-Pb age of 147.0±4.0 Ma,indicating magmatic activity during the Early Cretaceous.Three generations of arsenopyrite(Apy)are identified:Apy-1 in the altered granite,Apy-2 in the pegmatite dikes and Apy-3 in the quartz veins.The S/Fe ratios for Apy-1,Apy-2 and Apy-3 range from 0.98 to 1.09,0.89 to 0.92 and 0.86 to 1.02,respectively(average 0.97),suggesting a magmatic-hydrothermal origin.Sulfur isotope values(δ^(34)S=4.29‰-8.11‰)indicate that it was likely sourced from deep magmatic-hydrothermal fluids.Lead isotopic compositions of arsenopyrite suggest that the granitic parental magma is derived from the upper crust.These findings point to a magmatic-hydrothermal origin for the vein-type tungsten mineralization,linked to a concealed magmatichydrothermal system in the Early Cretaceous.
基金financed jointly by the National Major Science and Technology Special Project on Deep Earth Exploration(2024ZD1001701-5)the National Natural Science Foundation of China(42472127,42172086)+2 种基金the Yunnan Major Project of Basic Research(202401BN070001-002)Yunnan Mineral Resources Prediction and Evaluation Engineering Research Center(2011)Innovation Team Program of Kunming University of Science and Technology,Yunnan Province。
文摘The migration mechanisms of ore-forming fluids have long been a focus in the field of ore deposit studies.Calcite is ubiquitously present in various types of rocks in the lithosphere,and the underlying mechanisms of its influence on fluid migration are of crucial importance.While previous studies have revealed that salinity changes can modulate fluid migration,the underlying mechanisms remain poorly understood.We employ molecular dynamics simulations to elucidate how salinity variations in ore-forming fluids modulate the adsorption onto calcite nanopore walls,thereby revealing the microscopic mechanisms governing ore fluid transport through calcite nano-fractures.The results show that the adsorption energy Eint of the solution on the calcite surface increased from -14,948.84±182.48 kcal/mol to -12,144.08±118.2 kcal/mol as salinity increased,which is conducive to the long-range transport of the fluid in the calcite nanopore.
