Understanding the formation of lithium-rich pegmatites is critical for meeting global lithium demand.The 509 Daobanxi Li pegmatite deposit,located in the West Kunlun orogenic belt of northwestern China,represents a si...Understanding the formation of lithium-rich pegmatites is critical for meeting global lithium demand.The 509 Daobanxi Li pegmatite deposit,located in the West Kunlun orogenic belt of northwestern China,represents a significant example of an LCT-type(Li-Cs-Ta)pegmatite system.This study investigates the paragenetic sequence of lithium(Li)minerals and the factors controlling their crystallization,providing new insights into the magmatic-hydrothermal evolution of rare-element pegmatites.Pegmatite dikes exhibit distinct zonation,comprising a wall rock zone,a border zone(aplitic layer),and a core zone(pegmatitic layer),with Li mineralization concentrated in the pegmatitic and aplitic layers.The primary Li minerals include spodumene(Spd),montebrasite(Mbs),eucryptite(Ecr),elbaite(Elb),and lepidolite(Lpd),which crystallize in the order of spodumene→montebrasite→elbaite→lepidolite.Spodumene,the dominant Li-bearing mineral,crystallizes from a Li-saturated melt during the magmatic stage.Montebrasite,a Li-phosphate mineral,forms in P-rich environments,coexisting with spodumene and columbite-group minerals(CGM).During the magmatic-hydrothermal transition,elbaite crystallizes from a B-rich melt,exhibiting skeletal and patchy zoning due to undercooling and disequilibrium crystallization.Hydrothermal alteration leads to the breakdown of spodumene and the formation of secondary minerals such as eucryptite and lepidolite,with lepidolite being the final Li-bearing phase,enriched in fluorine.The coupled dissolution-precipitation processes during the magmatic-hydrothermal transition play a critical role in the remobilization and enrichment of rare elements such as Li,Nb,Ta,and Sn.This deposit,characterized by spodumene crystallization in the Spd+Quartz stability field(≥300 MPa,≤725℃)and subsequent alteration to Ecr+quartz assemblages(<270℃,<160 MPa),exhibits broader temperature-pressure conditions exceeding typical global pegmatites like Tanco,with no petalite formation observed due to its persistent exclusion from petalite stability fields throughout mineralization.The shear zone controls the pegmatite emplacement and lithium enrichment in the 509 Daobanxi lithium deposit,and its deformation-fluid coupling mechanism provides new insights for the exploration of LCT pegmatite deposits.The present study highlights the importance of understanding both magmatic and hydrothermal processes in the formation of LCT-type pegmatites and provides valuable insights for the exploration of critical metal resources in similar geological settings.展开更多
The Gabo lithium deposit represents a newly discovered pegmatite-type lithium deposit within the Himalayan metallogenic belt.The tourmaline-muscovite granite,the largest leucogranite in the mining area,displays a clos...The Gabo lithium deposit represents a newly discovered pegmatite-type lithium deposit within the Himalayan metallogenic belt.The tourmaline-muscovite granite,the largest leucogranite in the mining area,displays a close spatial correlation with the Li-pegmatite veins.This study aims to examine the genesis of tourmaline and evaluate the significance and potential of pegmatite lithium deposits.Tourmaline is extensively distributed in tourmaline-muscovite granite at Gabo deposit in Luozha county(Xizang).Investigation of the compositional and in situ boron isotopes of the tourmaline revealed that the tourmalines mainly belong to the schorl group and exhibit uniform elevated Li-Sn contents andδ^(11)B values(-11.6‰to-10.5‰).This indicates that the tourmaline mainly crystallized from a boron-rich granitic magma undergoing enrichment in elemental lithium during the tourmaline crystallization process.Compared with the principal rare metal leucogranite-pegmatites in the Himalayan orogen,it is proposed that the elevated lithium(Li)content of tourmaline serves as an eff ective mineral indicator for the highly evolved pegmatite-type rare metal deposits.展开更多
Highly evolved granite associated with pegmatite shells exhibits significant potential for rare metal mineralization;however,the mechanisms through which these pegmatite shells contribute to magmatic evolution and rar...Highly evolved granite associated with pegmatite shells exhibits significant potential for rare metal mineralization;however,the mechanisms through which these pegmatite shells contribute to magmatic evolution and rare metal enrichment remain poorly understood.The Late Jurassic Shihuiyao Nb-Ta-(Rb-Be-Li)deposit is one of the largest rare-metal deposits in the Southern Great Xing’an Range(SGXR),Northeast China.Exploratory trenches expose distinct layered zones from top to bottom:alternating microcline pegmatite and aplite layers(zone I),topaz lepidolite albite granite and lepidolite amazonite pegmatite(zone II),and muscovite albite granite(zoneⅢ).We conducted U-Pb dating of cassiterite,monazite,and Nb-Ta oxide,monazite Nd isotopes,and whole-rock and mineral geochemistry for the three zones.Multi-mineral U-Pb ages indicate that the three zones formed during the Late Jurassic-Early Cretaceous(147-142 Ma).Geochemical analyses of whole-rock,mica,and microcline suggest an evolutionary sequence from zone I to zoneⅢ,and finally to zone II.The Zr/Hf,Nb/Ta,Y/Ho,and K/Rb ratios combined with the rare earth element(REE)tetrad effects suggest higher degree of differentiation and fluid-melt interaction of the Shihuiyao leucogranite without a pegmatite shell compared to coeval barren granites from both Shihuiyao and the SGXR.A progressive increase in the degree of evolution is evident from the leucogranite without a pegmatite shell to the leucogranite with a discontinuous shell,and ultimately to the leucogranite with a continuous shell.The pegmatite shell acted as a geochemical barrier that facilitated the accumulation of Li and F in the underlying magma,which played a crucial role in lowering the solidus temperature of the granitic magma.This process prolonged the crystallization duration while reducing melt viscosity and density,thereby creating favorable conditions for magma differentiation and fluid-melt interaction.Rapid crystallization of the earlier water-and Be-rich melt led to the Be mineralization in the pegmatite shell.Moreover,the formation of this shell served as a barrier for Li mineralization in the underlying topaz lepidolite albite granite.This study enhances our understanding of the critical contribution of pegmatite shells to magmatic evolution and rare-metal mineralization.展开更多
The Duanfengshan deposit is a newly discovered large pegmatitic-type Nb-Ta deposit in the central section of the Jiangnan orogenic belt,South China.There are three types of pegmatite in the Duanfengshan area:microclin...The Duanfengshan deposit is a newly discovered large pegmatitic-type Nb-Ta deposit in the central section of the Jiangnan orogenic belt,South China.There are three types of pegmatite in the Duanfengshan area:microcline pegmatite,microcline-albite pegmatite and albite pegmatite.Although several geological,geochronological and geochemical studies of this deposit have been carried out,the relationships between the evolution degree of different types of pegmatites and mineralization are still unclear.We address this problem through systematic petrographic and geochemical studies of muscovite and feldspars from two representative pegmatite veins,the No.328 microcline-albite pegmatite vein,and the No.610 albite pegmatite vein.The results of electron probe microanalysis(EPMA)and laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)analyses of muscovite and K-feldspar reveal that K/Rb ratios decrease with increasing Rb,Cs,Ga,Nb and Ta contents alongside decreasing Ba and Sr contents,suggesting that magmatic differentiation played a dominant role in rare metal mineralization.A comparison of the analytical results of this study with those from rare metal pegmatites globally suggests that the No.610 vein has a high mineralization potential,whereas the No.328 vein has relatively low mineralization potential.The results from this study may be applied to the evaluation of mineralization potential for other pegmatite veins in the Duanfengshan area and other rare metal pegmatite fields with similar geological settings.展开更多
In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites,and for ore-forming processes related to granites than is usually assumed. We show that the supercritical me...In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites,and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H_2O are completely miscible in all proportions at magmatic temperatures and pressures. This phase evolves from felsic melts and changes into hydrothermal fluids, and its unique properties are particularly important in sequestering and concentrating low abundance elements, such as metals. In our past research, we have focused on processes observed at upper crustal levels, however extensive work by us and other researchers have demonstrated that supercritical melt/fluids should be abundant in melting zones at deep-crustal levels too. We propose that these fluids may provide a connecting link between lower and upper crustal magmas,and a highly efficient transport mechanism for usually melt incompatible elements. In this paper, we explore the unique features of this fluid which allow the partitioning of variouselements and compounds, potentially up to extreme levels,and may explain various features both of mineralization and the magmas that produced them.展开更多
Granitic pegmatites are commonly thought to form by fractional crystallization or by liquid immiscibility of granitic magma; however, these proposals are based mainly on analyses of fluid and melt inclusions. Here, we...Granitic pegmatites are commonly thought to form by fractional crystallization or by liquid immiscibility of granitic magma; however, these proposals are based mainly on analyses of fluid and melt inclusions. Here, we use the Jiajika pegmatite deposit, the largest spodumene deposit in Asia, as a case study to investigate ore forming processes using isotope dating. Dating of a single granite sample from the Jiajika deposit using multiple methods gave a zircon U-Pb SHRIMP age of 208.4 ~ 3.9 Ma, an 4~Ar/39Ar age for muscovite of 182.9 ~ 1.7 Ma, and an 4~Ar/39Ar age for biotite of 169.9 ＋ 1.6 Ma. Based on these dating results and the 4~Ar/39Ar age of muscovite from the Jiajika pegmatite, a temperature-time cooling track for the Jiajika granite was constructed using closure temperatures of the different isotope systems. This track indicates that the granite cooled over ^-40 m. y., with segregation of the pegmatite fluid from the granitic magma at a temperature of ~700~C. This result suggests that the Jiajika pegmatite formed not by fractional crystallization, but by segregation of an immiscible liquid from the granitic magma. When compared with fractional crystallization, the relatively early timing of segregation of an immiscible liquid from a granitic magma can prevent the precipitation of ore-forming elements during crystallization, and suggests that liquid immiscibility could be an important ore-forming process for rare metal pegmatities. We also conclude that isotope dating is a method that can potentially be used to determine the dominant ore-forming processes that occurred during the formation of granite-related ore deposits, and suggest that this method can be employed to determine the formation history of the W-Sn ore deposits found elsewhere within the Nanling Metallogenic Belt.展开更多
Fully-coupled thermo-mechanical simulations are implemented in COMSOL Multiphysics to investigate micro-scale stress-strain variability in pegmatite specimens subjected to thermal loading using microwaves. Thermally-i...Fully-coupled thermo-mechanical simulations are implemented in COMSOL Multiphysics to investigate micro-scale stress-strain variability in pegmatite specimens subjected to thermal loading using microwaves. Thermally-induced compressive and tensile stresses increase as the microwave irradiation duration increases. The dielectric constant, coefficient of expansion, and type and size of mineralogical boundary have significant impacts on the responses of the rock to microwave irradiation. The maximum principal stress of the chlorite is the smallest, indicating that the chlorite experiences the most damage under microwave irradiation, followed by the quartz. The maximum principal stress values of plagioclase and orthoclase are larger, indicating that they are likely to incur the least damage. Where quartz or chlorite is dominant, the resulting von Mises stresses are consistently higher after 120 s of microwave irradiation. The rate of generation of von Mises stresses increases most rapidly along the interface between quartz and plagioclase, and the interface between quartz and orthoclase, followed by the interface between quartz and chlorite, and finally the interface between plagioclase and orthoclase. The presented modeling approach provides a practical method to investigate stress-strain relationships within mineralogical boundaries inside a rock thin section.展开更多
The Zhawulong granitic pegmatite lithium deposit is located in the Ganzi-Songpan orogenic belt.Fluid inclusions in spodumene and coexisting quartz were studied to understand the cooling path and evolution of fluid wit...The Zhawulong granitic pegmatite lithium deposit is located in the Ganzi-Songpan orogenic belt.Fluid inclusions in spodumene and coexisting quartz were studied to understand the cooling path and evolution of fluid within albite–spodumene pegmatite.There are three distinguishable types of fluid inclusions:crystal-rich,CO2–NaCl–H2 O,and NaCl–H2 O.At more than 500°C and 350~480 MPa,crystal-rich fluid inclusions were captured during the pegmatitic magma-hydrothermal transition stage,characterized by a dense hydrous alkali borosilicate fluid with a carbonate component.Between 412°C and 278°C,CO2–Na Cl–H2 Ofluid inclusions developed in spodumene(I)and quartz(II)with a low salinity(3.3–11.9 wt%NaCl equivalent)and a high volatile content,which represent the boundary between the transition stage and the hydrothermal stage.The subsequentNaCl–H2 Ofluid inclusions from the hydrothermal stage,between 189°C and 302°C,have a low salinity(1.1–13.9 wt%NaCl equivalent).The various types of fluid inclusions reveal the P–T conditions of pegmatite formation,which marks the transition process from magmatic to hydrothermal.The oreforming fluids from the Zhawulong deposit have many of the same characteristics as those from the Jiajika lithium deposit.The ore-forming fluid provided not only materials for crystallization of rare metal minerals,such as spodumene and beryl,but also the ideal conditions forthe growth of ore minerals.Therefore,this area has favorable conditions for lithium enrichment and excellent prospecting potential.展开更多
In this study, we carried out petrography, zircon U-Pb geochronology and Hf isotopic analyses on a granitic pegmatite dyke in the Xiaoqinling area in southern margin of the North China Craton（NCC）. Our study suggest...In this study, we carried out petrography, zircon U-Pb geochronology and Hf isotopic analyses on a granitic pegmatite dyke in the Xiaoqinling area in southern margin of the North China Craton（NCC）. Our study suggests that the pegmatite dyke likely crystallized from a volatile-rich pegmatitic magma. Different from most other pegmatite elsewhere, zircon from this pegmatite dyke does not contain unusually high U and Th concentrations and suffered no evident radioactive damage, therefore we successfully obtained a zircon U-Pb dating using laser ablation-inductively coupled plasma-mass spectrometry（LA-ICP-MS）, which yields an average 207Pb/206 Pb age of 1 814±6 Ma, representing the intrusive age of the granitic pegmatite dyke. Zircon εHf（t） values are between-8.3 and-3.0, corresponding to Hf depleted mantle model ages from 2 649 to 2 991 Ma with an average of 2 881 Ma. These data indicate that this granitic pegmatite dyke may have been derived from partial melting of Meso-Neoarchean metamorphic rocks from the Xiaoqinling basement. Granitic pegmatite magma may have emplaced within the Taihua Group wall rocks during the last stage of the middle to high grade metamorphism. Furthermore, according to the petrographic observation, the 1.81 Ga pegmatite dyke and the 1 800–1 750 Ma Xiong’er Group rocks were not undergone middle to high grade metamorphism, indicating 1.81 Ga as the termination of the latest regional metamorphism in the southern margin of the NCC.展开更多
The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic belt.Compared to the porphyry deposits in the Gangdese belt,much less...The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic belt.Compared to the porphyry deposits in the Gangdese belt,much less researches have addressed these deposits,and the genesis of the Zhaxikang deposit is still controversial.Based on field investigation,petrographic,microthermometric,Laser Raman Microprobe（LRM） and SEM/EDS analyses of fluid,melt-fluid,melt and solid inclusions in quartz and beryl from pegmatite,this paper documents the characteristics and the evolution of primary magmatic fluid which was genetically related to greisenization,pegmatitization,and silification in the area.The results show that the primary magmatic fluids were derived from unmixing between melt and fluid and underwent a phase separation process soon after the exsolution.The primary magmatic fluids are of low salinity,high temperature,and can be approximated by the H_2O-NaCl-CO_2 system.The presence of Mn-Fe carbonate in melt-fluid inclusions and a Zn-bearing mineral（gahnite） trapped in beryl and in inclusions from pegmatite indicates high Mn,Fe,and Zn concentrations in the parent magma and magmatic fluids,and implies a genetic link between pegmatite and Pb-Zn-Sb mineralization.High B and F concentrations in the parent magma largely lower the solidus of the magma and lead to late fluid exsolution,thus the primary magmatic fluids related to pegmatite have much lower temperature than those in most porphyry systems.Boiling of the primary magmatic fluids leads to high-salinity and high-temperature fluids which have high capacity to transport Pb,Zn and Sb.The decrease in temperature and mixing with fluids from other sources may have caused the precipitation of Pb-Zn-Sn（Au） minerals in the distal fault systems surrounding the causative intrusion.展开更多
Remote sensing technique plays an important role in geological prospecting in Altay because of the remote location and steep terrain with mountains. Pegmatite has important implications for metallogenic prospecting as...Remote sensing technique plays an important role in geological prospecting in Altay because of the remote location and steep terrain with mountains. Pegmatite has important implications for metallogenic prospecting as most of rare metals occurs in it. Pegmatite information from optical and radar images was extracted, and the spatial distribution and scale of pegmatite were generalized in Azubai, Altay. Three mining targets, that is, Halon-Azubai, Kuermutu-Tuyibaguo and Zhuolute-Akuoyige, were delineated based on the analysis of pegmatite information, structure interpretation and other geological data.展开更多
Eastern Qinling,China is one of the important rare metal metallogenic provinces with extensively distributed granite pegmatite dikes.The No.5 granite pegmatite intruded into the granitic gneiss of the Qinling Group,an...Eastern Qinling,China is one of the important rare metal metallogenic provinces with extensively distributed granite pegmatite dikes.The No.5 granite pegmatite intruded into the granitic gneiss of the Qinling Group,and the major minerals are quartz(39.8%),K-feldspar(18.8%),albite(36.3%),muscovite(3.4%),and garnet(1.1%).Monazite U–Pb isotopic dating indicates that the No.5 pegmatite from the Eastern Qinling was emplaced at ca.420.2±2.2 Ma,which confirms that highpurity quartz mineralization probably formed during the Early Devonian.In-situ laser ablation inductively coupled plasma mass spectrometry analysis of quartz show that quartz samples from Eastern Qinling have total trace element concentrations(Al,Ti,Sc,Li,B,Cr,Mn,and Fe)ranging from 23.2 to 52.8 ppm,slightly higher than the quartz(impurity element content from 13.4 to 25.9 ppm)of the Spruce Pine high-purity quartz deposit in western North Carolina.The No.5 pegmatite of Eastern Qinling could be defined as one high-purity quartz deposit of China.展开更多
Western Altun in Xinjiang is an important area,where lithium(Li)-bearing pegmatites have been found in recent years.However,the complex terrain and harsh environment of western Altun exacerbates in prospecting for Li-...Western Altun in Xinjiang is an important area,where lithium(Li)-bearing pegmatites have been found in recent years.However,the complex terrain and harsh environment of western Altun exacerbates in prospecting for Li-bearing pegmatites.Therefore,remote-sensing techniques can be an effective means for prospecting Li-bearing pegmatites.In this study,the fault information and lithologyical information in the region were obtained using the median-resolution remotesensing image Landsat-8,the radar image Sentinel-1 and hyperspectral data GF-5.Using Landsat-8 data,the hydroxyl alteration information closely related to pegmatite in the region was extracted by principal component analysis,pseudoanomaly processing and other methods.The high spatial resolution remote-sensing data WorldView-2 and WorldView-3 short-wave infrared images were used and analyzed by principal component analysis(PCA),the band ratio method and multi-class machine learning(ML),combined with conventional thresholds specified the algorithms used to automatically extract Li-bearing pegmatite information.Finally,the Li-bearing pegmatite exploration area was determined,based on a comprehensive analysis of the faults,hydroxyl alteration lithology and Li-bearing pegmatite information.Field investigations have verified that the distribution of pegmatites in the central part of the study area is consistent with that of Li-bearing pegmatites extracted in this study.This study provides a new technique for prospecting Li-bearing pegmatites,which shows that remote-sensing technology possesses great potential for identifying lithium-bearing pegmatites,especially in areas that are not readily accessible.展开更多
Petrography and geochemistry of the altered and unaltered host rocks surrounding the Koktokay No.3 pegmatite revealed that the unaltered amphibolite is mainly composed of hornblende, plagioclase, and ilmenite.Beyond t...Petrography and geochemistry of the altered and unaltered host rocks surrounding the Koktokay No.3 pegmatite revealed that the unaltered amphibolite is mainly composed of hornblende, plagioclase, and ilmenite.Beyond these primary components, the altered host rocks contain a few newly formed minerals, including biotite,tourmaline, chlorine, and muscovite. The alteration zone surrounding the Koktokay No.3 pegmatite is limited to 2.0 m, characterized by biotitization, tourmalization, and chloritization. In the altered host rocks, the contents of SiO2, MgO, MnO, Na2O, and TiO2 did not vary greatly.However, Al2O3 showed a weak decreasing trend with the increasing distance from the pegmatite contact zone, while Fe2O3 and CaO showed an increasing trend. The contents of Li, Rb, and Cs in the altered host rocks were much higher than those in the unaltered host rocks, decreasing with distance from the contact. The chondrite-normalized rare earth element（REE） pattern of the altered and unaltered host rock was right-inclined from La to Lu, but enriched in light REEs over heavy REEs after hydrothermal alteration. An isocon plot shows that some oxides migrated in with an order of P2O5〉K2O 〉TiO2〉Al2O3〉SiO2〉MnO≥MgO, while others migrated out with an order of Na2O 〉CaO 〉Fe2O3. For REEs, the migration ratios are positive values withCs 〉Rb 〉Li 〉Nb 〉Ta 〉Be, signifying that all REEs migrated from the exsolved magmatic fluid into the altered host rocks. It was concluded that diffusion was the only mechanism for migration of ore-forming elements in the alteration zone. The effective diffusion coefficients（Deff）of LiF, RbF, and CsF were estimated under a fluid temperature of 500–550℃. Using a function of concentration（C（x,t）） and distance（x）, the order of migration distance was determined to be LiF 〉CsF 〉RbF, with diffusion times of （3.39 ± 0.35）× 10^6,（3.19 ± 0.28） × 10^5 and（6.33 ± 0.05） × 10^5 years, respectively.展开更多
1.Objectives Keeryin rare metal ore district is located at the intersection of Markam,Jinchuan and Rangtang counties.More than 1000 pegmatite dykes are associated with the Keeryin granite pluton.These pegmafite dykes ...1.Objectives Keeryin rare metal ore district is located at the intersection of Markam,Jinchuan and Rangtang counties.More than 1000 pegmatite dykes are associated with the Keeryin granite pluton.These pegmafite dykes are the major source of industrial spodumene ore bodies.Based on the previous studies,we chose Keeryin rare metal ore district as the key target area for geology survey.In this study,we discovered six pegmatite lithium veins in the Sizemuzu district of the Keeryin.Moreover,we study the distribution of regional ore deposits and metallogeny,delineate prospecting target and evaluate the mineralization potential of Lithium.展开更多
Abstract: The physico-chemical conditions under which the pegmatite dyke No. 3 was formed were discussed in the light of fluid-melt inclusion evidence. Our results lend support to the frac-tionation of hydrothermal so...Abstract: The physico-chemical conditions under which the pegmatite dyke No. 3 was formed were discussed in the light of fluid-melt inclusion evidence. Our results lend support to the frac-tionation of hydrothermal solutions from magma. For the pegmatite dike No. 3, the magma-derived hydrothermal solutions are dominated by NaCl + CO2 + H2O.展开更多
The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater ...The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater Himalayan Crystalline Complex(GHC),the Gyirong pegmatite in southern Tibet was chosen for geochronological and geochemical studies.The dating analyses indicate that the U-Th-Pb ages of zircon,monazite,and xenotime exhibit large variations(38.6‒16.1 Ma),with the weighted average value of the four youngest points is 16.5±0.3 Ma,which indicates that the final stage of crystallization of the melt occurred in the Miocene.The age of the muscovite Ar-Ar inverse isochron is 15.2±0.4 Ma,which is slightly later than the intrusion age,showing that a cooling process associated with rapid denudation occurred at 16‒15 Ma.TheεHf(t)values of the Cenozoic anatectic zircons cluster between−12 and−9 with an average of−11.4.The Gyirong pegmatite shows high contents of Si,Al,and K,a high Al saturation index,and low contents of Na,Ca,Fe,Mn,P,Mg,and Ti.Overall,the Gyirong pegmatite is enriched in Rb,Cs,U,K,Th and Pb and depleted in Nb,Ta,Zr,Ti,Eu,Sr,and Ba.The samples show a high 87Sr/86Sr(16 Ma)ratio of ca.0.762 and a lowεNd(16 Ma)value of−16.0.The calculated average initial values of 208Pb/204Pb(16 Ma),207Pb/204Pb(16 Ma)and 206Pb/204Pb(16 Ma)of the whole rock are 39.72,15.79 and 19.56,respectively.The Sr-Nd-Pb-Hf isotopic characteristics of the Gyirong pegmatite are consistent with those of the GHC.This study concludes that the Gyirong pegmatite represents a typical crustal‒derived anatectic pegmatite with low metallogenic potential for rare metals.The Gyirong pegmatite records the long‒term metamorphism and partial melting process of the GHC,and reflects the crustal thickening caused by thrust compression at 39‒29 Ma and the crustal thinning induced by extensional decompression during 28‒15 Ma.展开更多
The Guanpo pegmatite field in the North Qinling orogenic belt(NQB),China,hosts the most abundant LCT pegmatites.However,their emplacement conditions and structural control remain unexplored.In this contribution,we inv...The Guanpo pegmatite field in the North Qinling orogenic belt(NQB),China,hosts the most abundant LCT pegmatites.However,their emplacement conditions and structural control remain unexplored.In this contribution,we investigated it combining pegmatite orientation measurement with oxygen isotope geothermometry and fluid inclusion study.The orientations of type A1 pegmatites(P_(f)<σ_(2))are predominantly influenced by P-and T-fractures due to simple shearing in Shiziping dextral thrust shear zone during D_(2)deformation,whereas type A2 pegmatites(contemporaneous with D_(4))are governed by hydraulic fractures aligned with S_(0)and S_(0+1)stemming from fluid pressure(P_(f)<σ_(2)).Additionally,type B pegmatites(P_(f)≤σ_(2))exhibit orientations shaped by en echelon extensional fractures in local ductile shear zones(contemporaneous with D_(3)).The albite-quartz oxygen isotope geothermometry and microthermometric analysis of fluid inclusions in elbaites from the latest pegmatites(including types B and A2)suggest that the crystallization P-T for late magmatic and hydrothermal stages are 527.5-559.2℃,320℃,3.1-3.6 kbar and 2.0 kbar,respectively.Our observations along with previous studies suggest that the genesis of the LCT pegmatites was a long-term,multi-stage event during early Paleozoic orogeny(including the collision stage)of the NQB,and was facilitated by various local fractures.展开更多
There are two main granitic rocks cropping out in the study area:1) the syn-orogenic granites are moderately weathered,jointed,exfoliated and characterized by low relief.These rocks are subdivided into tonalite and gr...There are two main granitic rocks cropping out in the study area:1) the syn-orogenic granites are moderately weathered,jointed,exfoliated and characterized by low relief.These rocks are subdivided into tonalite and granodiorite.They are essentially composed of plagioclase,quartz,biotite,hornblende and potash feldspar;and 2) the post-orogenic granites,characterized by high relief terrain and represented by monzogranite,syenogranite and alkali granite.The monzogranites suffered hydrothermal alteration in particular along joints,faults,shear zones and fractures,which recorded the highest values of radioactivity,reflecting the role of post-magmatic alteration processes in the enhancement of radioactivity.The hydrothermal alteration(desilicification and hematitization) resulted in the formation of mineralized(altered) granites.The altered granites are enriched in TiO 2,Al 2 O 3,FeO T,MnO,MgO,Na 2 O,Rb,Sr,Y,Zr,Zn,Ga and Co and depleted in SiO 2,CaO,P 2 O 5,Nb,Pb,Cu,Ni and Cr relative to the fresh monzogranite.The investigated granites contain basic xenoliths as well as pockets of pegmatites.Perthites,quartz,plagioclase and sometimes biotite,represent the essential constituents.Some accessory minerals like zircon are metamicted reflecting their radiogenic nature.The alkali granites are characterized by the presence of aegirine,rebeckite and arfvedsonite.Both syn-and post-orogenic granites show some variations in their bulk chemical compositions.The older granitoids are metaluminous and exhibit characteristics of I-type granites and possess an arc tectonic environment.On the other hand,the younger granites are peraluminous and exhibit the characteristics of post-collisional granites.It is interpreted that radioactivity of the studied rocks is mainly controlled by both magmatic and post-magmatic activities.Frequently,the post-orogenic granites host zoned and unzoned pegmatite pockets.Some of these pockets anomalously attain high radioactivity.The syenogranites and the pegmatites are characterized by high contents of SiO 2 and K 2 O and low CaO and MgO.They have transitional characters from highly fractionated calc-alkaline to alkaline.The alkali granites related to A2-subtype of A-type granites.The post-orogenic granites were originated from magma of dominant crustal source materials and related to post-collisional setting under extensional environment.展开更多
This article is investigating analysis and chemical composition of ceramic pegmatite minerals obtained from the Terek deposit in Toktogul district of Kyrgyzstan. Several methods such as mineralogical studies, magnetic...This article is investigating analysis and chemical composition of ceramic pegmatite minerals obtained from the Terek deposit in Toktogul district of Kyrgyzstan. Several methods such as mineralogical studies, magnetic and gravitational enrichments, silicate and chemical analyses of ceramic pegmatite minerals, quartz-feldspathic concentrate and sludge removal have been performed for determination of pegmatite mineral applicability for production of porcelain and earthenware.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42250202,92162323,42272075)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.24lgqb01).
文摘Understanding the formation of lithium-rich pegmatites is critical for meeting global lithium demand.The 509 Daobanxi Li pegmatite deposit,located in the West Kunlun orogenic belt of northwestern China,represents a significant example of an LCT-type(Li-Cs-Ta)pegmatite system.This study investigates the paragenetic sequence of lithium(Li)minerals and the factors controlling their crystallization,providing new insights into the magmatic-hydrothermal evolution of rare-element pegmatites.Pegmatite dikes exhibit distinct zonation,comprising a wall rock zone,a border zone(aplitic layer),and a core zone(pegmatitic layer),with Li mineralization concentrated in the pegmatitic and aplitic layers.The primary Li minerals include spodumene(Spd),montebrasite(Mbs),eucryptite(Ecr),elbaite(Elb),and lepidolite(Lpd),which crystallize in the order of spodumene→montebrasite→elbaite→lepidolite.Spodumene,the dominant Li-bearing mineral,crystallizes from a Li-saturated melt during the magmatic stage.Montebrasite,a Li-phosphate mineral,forms in P-rich environments,coexisting with spodumene and columbite-group minerals(CGM).During the magmatic-hydrothermal transition,elbaite crystallizes from a B-rich melt,exhibiting skeletal and patchy zoning due to undercooling and disequilibrium crystallization.Hydrothermal alteration leads to the breakdown of spodumene and the formation of secondary minerals such as eucryptite and lepidolite,with lepidolite being the final Li-bearing phase,enriched in fluorine.The coupled dissolution-precipitation processes during the magmatic-hydrothermal transition play a critical role in the remobilization and enrichment of rare elements such as Li,Nb,Ta,and Sn.This deposit,characterized by spodumene crystallization in the Spd+Quartz stability field(≥300 MPa,≤725℃)and subsequent alteration to Ecr+quartz assemblages(<270℃,<160 MPa),exhibits broader temperature-pressure conditions exceeding typical global pegmatites like Tanco,with no petalite formation observed due to its persistent exclusion from petalite stability fields throughout mineralization.The shear zone controls the pegmatite emplacement and lithium enrichment in the 509 Daobanxi lithium deposit,and its deformation-fluid coupling mechanism provides new insights for the exploration of LCT pegmatite deposits.The present study highlights the importance of understanding both magmatic and hydrothermal processes in the formation of LCT-type pegmatites and provides valuable insights for the exploration of critical metal resources in similar geological settings.
基金The National Key Research and Development Program of China(No.2021YFC2901903)the National Key Research and Development Program of China(No.2023YFC2906805)+1 种基金the Second Comprehensive Scientific Expedition to the Qinghai-Tibet Plateau(No.2019QZKK0806)the Geological Survey Project of China Geological Survey,(Nos.DD20240071,DD20240014,DD20211690,DD20240069)。
文摘The Gabo lithium deposit represents a newly discovered pegmatite-type lithium deposit within the Himalayan metallogenic belt.The tourmaline-muscovite granite,the largest leucogranite in the mining area,displays a close spatial correlation with the Li-pegmatite veins.This study aims to examine the genesis of tourmaline and evaluate the significance and potential of pegmatite lithium deposits.Tourmaline is extensively distributed in tourmaline-muscovite granite at Gabo deposit in Luozha county(Xizang).Investigation of the compositional and in situ boron isotopes of the tourmaline revealed that the tourmalines mainly belong to the schorl group and exhibit uniform elevated Li-Sn contents andδ^(11)B values(-11.6‰to-10.5‰).This indicates that the tourmaline mainly crystallized from a boron-rich granitic magma undergoing enrichment in elemental lithium during the tourmaline crystallization process.Compared with the principal rare metal leucogranite-pegmatites in the Himalayan orogen,it is proposed that the elevated lithium(Li)content of tourmaline serves as an eff ective mineral indicator for the highly evolved pegmatite-type rare metal deposits.
基金supported by the Key Research Program of the Institute of Geology&Geophysics,CAS(IGGCAS-202205)the National Natural Science Foundation of China(Grant No.92062216 and 42102046)+1 种基金Doctoral Students'Scientific Research and Innovation Capability Enhancement Program of Jilin Province(JJKH20250074BS)Graduate Innovation Fund of Jilin University(2024CX231).
文摘Highly evolved granite associated with pegmatite shells exhibits significant potential for rare metal mineralization;however,the mechanisms through which these pegmatite shells contribute to magmatic evolution and rare metal enrichment remain poorly understood.The Late Jurassic Shihuiyao Nb-Ta-(Rb-Be-Li)deposit is one of the largest rare-metal deposits in the Southern Great Xing’an Range(SGXR),Northeast China.Exploratory trenches expose distinct layered zones from top to bottom:alternating microcline pegmatite and aplite layers(zone I),topaz lepidolite albite granite and lepidolite amazonite pegmatite(zone II),and muscovite albite granite(zoneⅢ).We conducted U-Pb dating of cassiterite,monazite,and Nb-Ta oxide,monazite Nd isotopes,and whole-rock and mineral geochemistry for the three zones.Multi-mineral U-Pb ages indicate that the three zones formed during the Late Jurassic-Early Cretaceous(147-142 Ma).Geochemical analyses of whole-rock,mica,and microcline suggest an evolutionary sequence from zone I to zoneⅢ,and finally to zone II.The Zr/Hf,Nb/Ta,Y/Ho,and K/Rb ratios combined with the rare earth element(REE)tetrad effects suggest higher degree of differentiation and fluid-melt interaction of the Shihuiyao leucogranite without a pegmatite shell compared to coeval barren granites from both Shihuiyao and the SGXR.A progressive increase in the degree of evolution is evident from the leucogranite without a pegmatite shell to the leucogranite with a discontinuous shell,and ultimately to the leucogranite with a continuous shell.The pegmatite shell acted as a geochemical barrier that facilitated the accumulation of Li and F in the underlying magma,which played a crucial role in lowering the solidus temperature of the granitic magma.This process prolonged the crystallization duration while reducing melt viscosity and density,thereby creating favorable conditions for magma differentiation and fluid-melt interaction.Rapid crystallization of the earlier water-and Be-rich melt led to the Be mineralization in the pegmatite shell.Moreover,the formation of this shell served as a barrier for Li mineralization in the underlying topaz lepidolite albite granite.This study enhances our understanding of the critical contribution of pegmatite shells to magmatic evolution and rare-metal mineralization.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42102110,U2444204,42472111 and U2344220).
文摘The Duanfengshan deposit is a newly discovered large pegmatitic-type Nb-Ta deposit in the central section of the Jiangnan orogenic belt,South China.There are three types of pegmatite in the Duanfengshan area:microcline pegmatite,microcline-albite pegmatite and albite pegmatite.Although several geological,geochronological and geochemical studies of this deposit have been carried out,the relationships between the evolution degree of different types of pegmatites and mineralization are still unclear.We address this problem through systematic petrographic and geochemical studies of muscovite and feldspars from two representative pegmatite veins,the No.328 microcline-albite pegmatite vein,and the No.610 albite pegmatite vein.The results of electron probe microanalysis(EPMA)and laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)analyses of muscovite and K-feldspar reveal that K/Rb ratios decrease with increasing Rb,Cs,Ga,Nb and Ta contents alongside decreasing Ba and Sr contents,suggesting that magmatic differentiation played a dominant role in rare metal mineralization.A comparison of the analytical results of this study with those from rare metal pegmatites globally suggests that the No.610 vein has a high mineralization potential,whereas the No.328 vein has relatively low mineralization potential.The results from this study may be applied to the evaluation of mineralization potential for other pegmatite veins in the Duanfengshan area and other rare metal pegmatite fields with similar geological settings.
文摘In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites,and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H_2O are completely miscible in all proportions at magmatic temperatures and pressures. This phase evolves from felsic melts and changes into hydrothermal fluids, and its unique properties are particularly important in sequestering and concentrating low abundance elements, such as metals. In our past research, we have focused on processes observed at upper crustal levels, however extensive work by us and other researchers have demonstrated that supercritical melt/fluids should be abundant in melting zones at deep-crustal levels too. We propose that these fluids may provide a connecting link between lower and upper crustal magmas,and a highly efficient transport mechanism for usually melt incompatible elements. In this paper, we explore the unique features of this fluid which allow the partitioning of variouselements and compounds, potentially up to extreme levels,and may explain various features both of mineralization and the magmas that produced them.
基金supported by grants from the National Natural Science Foundation of China (40702014)the China Postdoctoral Science Foundation (2008044018,200902580)+1 种基金the Chinese SinoProbe Project (SinoProbe-03-01)the National Nonprofit Institute Research Grant of IMR,GAGS(K1001)
文摘Granitic pegmatites are commonly thought to form by fractional crystallization or by liquid immiscibility of granitic magma; however, these proposals are based mainly on analyses of fluid and melt inclusions. Here, we use the Jiajika pegmatite deposit, the largest spodumene deposit in Asia, as a case study to investigate ore forming processes using isotope dating. Dating of a single granite sample from the Jiajika deposit using multiple methods gave a zircon U-Pb SHRIMP age of 208.4 ~ 3.9 Ma, an 4~Ar/39Ar age for muscovite of 182.9 ~ 1.7 Ma, and an 4~Ar/39Ar age for biotite of 169.9 ＋ 1.6 Ma. Based on these dating results and the 4~Ar/39Ar age of muscovite from the Jiajika pegmatite, a temperature-time cooling track for the Jiajika granite was constructed using closure temperatures of the different isotope systems. This track indicates that the granite cooled over ^-40 m. y., with segregation of the pegmatite fluid from the granitic magma at a temperature of ~700~C. This result suggests that the Jiajika pegmatite formed not by fractional crystallization, but by segregation of an immiscible liquid from the granitic magma. When compared with fractional crystallization, the relatively early timing of segregation of an immiscible liquid from a granitic magma can prevent the precipitation of ore-forming elements during crystallization, and suggests that liquid immiscibility could be an important ore-forming process for rare metal pegmatities. We also conclude that isotope dating is a method that can potentially be used to determine the dominant ore-forming processes that occurred during the formation of granite-related ore deposits, and suggest that this method can be employed to determine the formation history of the W-Sn ore deposits found elsewhere within the Nanling Metallogenic Belt.
基金supported by the US National Science Foundation (CMMI award 1550307)the China Scholarship Council for financial support as a visiting scholar at the Colorado School of Mines (Grant No. 201706375077)
文摘Fully-coupled thermo-mechanical simulations are implemented in COMSOL Multiphysics to investigate micro-scale stress-strain variability in pegmatite specimens subjected to thermal loading using microwaves. Thermally-induced compressive and tensile stresses increase as the microwave irradiation duration increases. The dielectric constant, coefficient of expansion, and type and size of mineralogical boundary have significant impacts on the responses of the rock to microwave irradiation. The maximum principal stress of the chlorite is the smallest, indicating that the chlorite experiences the most damage under microwave irradiation, followed by the quartz. The maximum principal stress values of plagioclase and orthoclase are larger, indicating that they are likely to incur the least damage. Where quartz or chlorite is dominant, the resulting von Mises stresses are consistently higher after 120 s of microwave irradiation. The rate of generation of von Mises stresses increases most rapidly along the interface between quartz and plagioclase, and the interface between quartz and orthoclase, followed by the interface between quartz and chlorite, and finally the interface between plagioclase and orthoclase. The presented modeling approach provides a practical method to investigate stress-strain relationships within mineralogical boundaries inside a rock thin section.
基金funded by the National Natural Science Foundation of China(No.41703048,41872096)the Chinese National Nonprofit Institute Research Grant of CAGS,CGS(YYWF201520,JYYWF201814)the China Geological Survey(DD20160055,DD20190173)
文摘The Zhawulong granitic pegmatite lithium deposit is located in the Ganzi-Songpan orogenic belt.Fluid inclusions in spodumene and coexisting quartz were studied to understand the cooling path and evolution of fluid within albite–spodumene pegmatite.There are three distinguishable types of fluid inclusions:crystal-rich,CO2–NaCl–H2 O,and NaCl–H2 O.At more than 500°C and 350~480 MPa,crystal-rich fluid inclusions were captured during the pegmatitic magma-hydrothermal transition stage,characterized by a dense hydrous alkali borosilicate fluid with a carbonate component.Between 412°C and 278°C,CO2–Na Cl–H2 Ofluid inclusions developed in spodumene(I)and quartz(II)with a low salinity(3.3–11.9 wt%NaCl equivalent)and a high volatile content,which represent the boundary between the transition stage and the hydrothermal stage.The subsequentNaCl–H2 Ofluid inclusions from the hydrothermal stage,between 189°C and 302°C,have a low salinity(1.1–13.9 wt%NaCl equivalent).The various types of fluid inclusions reveal the P–T conditions of pegmatite formation,which marks the transition process from magmatic to hydrothermal.The oreforming fluids from the Zhawulong deposit have many of the same characteristics as those from the Jiajika lithium deposit.The ore-forming fluid provided not only materials for crystallization of rare metal minerals,such as spodumene and beryl,but also the ideal conditions forthe growth of ore minerals.Therefore,this area has favorable conditions for lithium enrichment and excellent prospecting potential.
基金financially supported by the National Key Basic Research Program of China (No. 2006CB403506)the National Natural Science Foundation of China (No. 41203011)the Fundamental Research Funds for the Central Universities (No. 2013B03014)
文摘In this study, we carried out petrography, zircon U-Pb geochronology and Hf isotopic analyses on a granitic pegmatite dyke in the Xiaoqinling area in southern margin of the North China Craton（NCC）. Our study suggests that the pegmatite dyke likely crystallized from a volatile-rich pegmatitic magma. Different from most other pegmatite elsewhere, zircon from this pegmatite dyke does not contain unusually high U and Th concentrations and suffered no evident radioactive damage, therefore we successfully obtained a zircon U-Pb dating using laser ablation-inductively coupled plasma-mass spectrometry（LA-ICP-MS）, which yields an average 207Pb/206 Pb age of 1 814±6 Ma, representing the intrusive age of the granitic pegmatite dyke. Zircon εHf（t） values are between-8.3 and-3.0, corresponding to Hf depleted mantle model ages from 2 649 to 2 991 Ma with an average of 2 881 Ma. These data indicate that this granitic pegmatite dyke may have been derived from partial melting of Meso-Neoarchean metamorphic rocks from the Xiaoqinling basement. Granitic pegmatite magma may have emplaced within the Taihua Group wall rocks during the last stage of the middle to high grade metamorphism. Furthermore, according to the petrographic observation, the 1.81 Ga pegmatite dyke and the 1 800–1 750 Ma Xiong’er Group rocks were not undergone middle to high grade metamorphism, indicating 1.81 Ga as the termination of the latest regional metamorphism in the southern margin of the NCC.
基金financially supported by the State Basic Research Plan(973 project)(No.2011CB403100)IGCP/SIDA-600 project
文摘The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic belt.Compared to the porphyry deposits in the Gangdese belt,much less researches have addressed these deposits,and the genesis of the Zhaxikang deposit is still controversial.Based on field investigation,petrographic,microthermometric,Laser Raman Microprobe（LRM） and SEM/EDS analyses of fluid,melt-fluid,melt and solid inclusions in quartz and beryl from pegmatite,this paper documents the characteristics and the evolution of primary magmatic fluid which was genetically related to greisenization,pegmatitization,and silification in the area.The results show that the primary magmatic fluids were derived from unmixing between melt and fluid and underwent a phase separation process soon after the exsolution.The primary magmatic fluids are of low salinity,high temperature,and can be approximated by the H_2O-NaCl-CO_2 system.The presence of Mn-Fe carbonate in melt-fluid inclusions and a Zn-bearing mineral（gahnite） trapped in beryl and in inclusions from pegmatite indicates high Mn,Fe,and Zn concentrations in the parent magma and magmatic fluids,and implies a genetic link between pegmatite and Pb-Zn-Sb mineralization.High B and F concentrations in the parent magma largely lower the solidus of the magma and lead to late fluid exsolution,thus the primary magmatic fluids related to pegmatite have much lower temperature than those in most porphyry systems.Boiling of the primary magmatic fluids leads to high-salinity and high-temperature fluids which have high capacity to transport Pb,Zn and Sb.The decrease in temperature and mixing with fluids from other sources may have caused the precipitation of Pb-Zn-Sn（Au） minerals in the distal fault systems surrounding the causative intrusion.
基金Project(11JJ6029)supported by Natural Science Foundation of Hunan Province,ChinaProject(2011QNZT006)supported by Fundamental Research Funds for the Central Universities,China
文摘Remote sensing technique plays an important role in geological prospecting in Altay because of the remote location and steep terrain with mountains. Pegmatite has important implications for metallogenic prospecting as most of rare metals occurs in it. Pegmatite information from optical and radar images was extracted, and the spatial distribution and scale of pegmatite were generalized in Azubai, Altay. Three mining targets, that is, Halon-Azubai, Kuermutu-Tuyibaguo and Zhuolute-Akuoyige, were delineated based on the analysis of pegmatite information, structure interpretation and other geological data.
基金the National Natural Science Foundation of China(42062006 and 41962007)the National Key Research and Development Program of China(2016YFC0600207)+1 种基金the Project of China Geological Survey(DD20190186 and 12120114034501)the science and technology research project of Jiangxi Provincial Department of Education(GJJ190379)。
文摘Eastern Qinling,China is one of the important rare metal metallogenic provinces with extensively distributed granite pegmatite dikes.The No.5 granite pegmatite intruded into the granitic gneiss of the Qinling Group,and the major minerals are quartz(39.8%),K-feldspar(18.8%),albite(36.3%),muscovite(3.4%),and garnet(1.1%).Monazite U–Pb isotopic dating indicates that the No.5 pegmatite from the Eastern Qinling was emplaced at ca.420.2±2.2 Ma,which confirms that highpurity quartz mineralization probably formed during the Early Devonian.In-situ laser ablation inductively coupled plasma mass spectrometry analysis of quartz show that quartz samples from Eastern Qinling have total trace element concentrations(Al,Ti,Sc,Li,B,Cr,Mn,and Fe)ranging from 23.2 to 52.8 ppm,slightly higher than the quartz(impurity element content from 13.4 to 25.9 ppm)of the Spruce Pine high-purity quartz deposit in western North Carolina.The No.5 pegmatite of Eastern Qinling could be defined as one high-purity quartz deposit of China.
基金supported by the National Key Research and Development Program of the China Geological Survey(DD20190173)the Fundamental Research Funds for the Institute of Mineral Resources,the Chinese Academy of Geological Sciences(KK2102)+1 种基金the National Natural Science Foundation of China(42172332)the Chinese Geological Survey Project(DD20190379)。
文摘Western Altun in Xinjiang is an important area,where lithium(Li)-bearing pegmatites have been found in recent years.However,the complex terrain and harsh environment of western Altun exacerbates in prospecting for Li-bearing pegmatites.Therefore,remote-sensing techniques can be an effective means for prospecting Li-bearing pegmatites.In this study,the fault information and lithologyical information in the region were obtained using the median-resolution remotesensing image Landsat-8,the radar image Sentinel-1 and hyperspectral data GF-5.Using Landsat-8 data,the hydroxyl alteration information closely related to pegmatite in the region was extracted by principal component analysis,pseudoanomaly processing and other methods.The high spatial resolution remote-sensing data WorldView-2 and WorldView-3 short-wave infrared images were used and analyzed by principal component analysis(PCA),the band ratio method and multi-class machine learning(ML),combined with conventional thresholds specified the algorithms used to automatically extract Li-bearing pegmatite information.Finally,the Li-bearing pegmatite exploration area was determined,based on a comprehensive analysis of the faults,hydroxyl alteration lithology and Li-bearing pegmatite information.Field investigations have verified that the distribution of pegmatites in the central part of the study area is consistent with that of Li-bearing pegmatites extracted in this study.This study provides a new technique for prospecting Li-bearing pegmatites,which shows that remote-sensing technology possesses great potential for identifying lithium-bearing pegmatites,especially in areas that are not readily accessible.
基金supported jointly by the Natural Science Foundation of China (Grant No.41372104)Research Project of Xinjiang Nonferrous Metals Industry (Group) Co.,Ltd.(Grant No.YSKY2011-02)
文摘Petrography and geochemistry of the altered and unaltered host rocks surrounding the Koktokay No.3 pegmatite revealed that the unaltered amphibolite is mainly composed of hornblende, plagioclase, and ilmenite.Beyond these primary components, the altered host rocks contain a few newly formed minerals, including biotite,tourmaline, chlorine, and muscovite. The alteration zone surrounding the Koktokay No.3 pegmatite is limited to 2.0 m, characterized by biotitization, tourmalization, and chloritization. In the altered host rocks, the contents of SiO2, MgO, MnO, Na2O, and TiO2 did not vary greatly.However, Al2O3 showed a weak decreasing trend with the increasing distance from the pegmatite contact zone, while Fe2O3 and CaO showed an increasing trend. The contents of Li, Rb, and Cs in the altered host rocks were much higher than those in the unaltered host rocks, decreasing with distance from the contact. The chondrite-normalized rare earth element（REE） pattern of the altered and unaltered host rock was right-inclined from La to Lu, but enriched in light REEs over heavy REEs after hydrothermal alteration. An isocon plot shows that some oxides migrated in with an order of P2O5〉K2O 〉TiO2〉Al2O3〉SiO2〉MnO≥MgO, while others migrated out with an order of Na2O 〉CaO 〉Fe2O3. For REEs, the migration ratios are positive values withCs 〉Rb 〉Li 〉Nb 〉Ta 〉Be, signifying that all REEs migrated from the exsolved magmatic fluid into the altered host rocks. It was concluded that diffusion was the only mechanism for migration of ore-forming elements in the alteration zone. The effective diffusion coefficients（Deff）of LiF, RbF, and CsF were estimated under a fluid temperature of 500–550℃. Using a function of concentration（C（x,t）） and distance（x）, the order of migration distance was determined to be LiF 〉CsF 〉RbF, with diffusion times of （3.39 ± 0.35）× 10^6,（3.19 ± 0.28） × 10^5 and（6.33 ± 0.05） × 10^5 years, respectively.
文摘1.Objectives Keeryin rare metal ore district is located at the intersection of Markam,Jinchuan and Rangtang counties.More than 1000 pegmatite dykes are associated with the Keeryin granite pluton.These pegmafite dykes are the major source of industrial spodumene ore bodies.Based on the previous studies,we chose Keeryin rare metal ore district as the key target area for geology survey.In this study,we discovered six pegmatite lithium veins in the Sizemuzu district of the Keeryin.Moreover,we study the distribution of regional ore deposits and metallogeny,delineate prospecting target and evaluate the mineralization potential of Lithium.
文摘Abstract: The physico-chemical conditions under which the pegmatite dyke No. 3 was formed were discussed in the light of fluid-melt inclusion evidence. Our results lend support to the frac-tionation of hydrothermal solutions from magma. For the pegmatite dike No. 3, the magma-derived hydrothermal solutions are dominated by NaCl + CO2 + H2O.
基金sponsored by the National Key R&D Programme of China(2021YFC2901803)National Natural Science Foundation of China(92055314 and 41802095)+2 种基金the China Geological Survey(DD20230049 and DD20220983)is a contribution to the International Geoscience Programme(IGCP-741)Academician Bao-jun Liu Foundation of Southwest Geological Science and Technology Innovation Center.
文摘The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater Himalayan Crystalline Complex(GHC),the Gyirong pegmatite in southern Tibet was chosen for geochronological and geochemical studies.The dating analyses indicate that the U-Th-Pb ages of zircon,monazite,and xenotime exhibit large variations(38.6‒16.1 Ma),with the weighted average value of the four youngest points is 16.5±0.3 Ma,which indicates that the final stage of crystallization of the melt occurred in the Miocene.The age of the muscovite Ar-Ar inverse isochron is 15.2±0.4 Ma,which is slightly later than the intrusion age,showing that a cooling process associated with rapid denudation occurred at 16‒15 Ma.TheεHf(t)values of the Cenozoic anatectic zircons cluster between−12 and−9 with an average of−11.4.The Gyirong pegmatite shows high contents of Si,Al,and K,a high Al saturation index,and low contents of Na,Ca,Fe,Mn,P,Mg,and Ti.Overall,the Gyirong pegmatite is enriched in Rb,Cs,U,K,Th and Pb and depleted in Nb,Ta,Zr,Ti,Eu,Sr,and Ba.The samples show a high 87Sr/86Sr(16 Ma)ratio of ca.0.762 and a lowεNd(16 Ma)value of−16.0.The calculated average initial values of 208Pb/204Pb(16 Ma),207Pb/204Pb(16 Ma)and 206Pb/204Pb(16 Ma)of the whole rock are 39.72,15.79 and 19.56,respectively.The Sr-Nd-Pb-Hf isotopic characteristics of the Gyirong pegmatite are consistent with those of the GHC.This study concludes that the Gyirong pegmatite represents a typical crustal‒derived anatectic pegmatite with low metallogenic potential for rare metals.The Gyirong pegmatite records the long‒term metamorphism and partial melting process of the GHC,and reflects the crustal thickening caused by thrust compression at 39‒29 Ma and the crustal thinning induced by extensional decompression during 28‒15 Ma.
基金supported by the National Key R&D Program of China(Grant Nos.2021YFC2901902 and 2019YFC0605202)。
文摘The Guanpo pegmatite field in the North Qinling orogenic belt(NQB),China,hosts the most abundant LCT pegmatites.However,their emplacement conditions and structural control remain unexplored.In this contribution,we investigated it combining pegmatite orientation measurement with oxygen isotope geothermometry and fluid inclusion study.The orientations of type A1 pegmatites(P_(f)<σ_(2))are predominantly influenced by P-and T-fractures due to simple shearing in Shiziping dextral thrust shear zone during D_(2)deformation,whereas type A2 pegmatites(contemporaneous with D_(4))are governed by hydraulic fractures aligned with S_(0)and S_(0+1)stemming from fluid pressure(P_(f)<σ_(2)).Additionally,type B pegmatites(P_(f)≤σ_(2))exhibit orientations shaped by en echelon extensional fractures in local ductile shear zones(contemporaneous with D_(3)).The albite-quartz oxygen isotope geothermometry and microthermometric analysis of fluid inclusions in elbaites from the latest pegmatites(including types B and A2)suggest that the crystallization P-T for late magmatic and hydrothermal stages are 527.5-559.2℃,320℃,3.1-3.6 kbar and 2.0 kbar,respectively.Our observations along with previous studies suggest that the genesis of the LCT pegmatites was a long-term,multi-stage event during early Paleozoic orogeny(including the collision stage)of the NQB,and was facilitated by various local fractures.
文摘There are two main granitic rocks cropping out in the study area:1) the syn-orogenic granites are moderately weathered,jointed,exfoliated and characterized by low relief.These rocks are subdivided into tonalite and granodiorite.They are essentially composed of plagioclase,quartz,biotite,hornblende and potash feldspar;and 2) the post-orogenic granites,characterized by high relief terrain and represented by monzogranite,syenogranite and alkali granite.The monzogranites suffered hydrothermal alteration in particular along joints,faults,shear zones and fractures,which recorded the highest values of radioactivity,reflecting the role of post-magmatic alteration processes in the enhancement of radioactivity.The hydrothermal alteration(desilicification and hematitization) resulted in the formation of mineralized(altered) granites.The altered granites are enriched in TiO 2,Al 2 O 3,FeO T,MnO,MgO,Na 2 O,Rb,Sr,Y,Zr,Zn,Ga and Co and depleted in SiO 2,CaO,P 2 O 5,Nb,Pb,Cu,Ni and Cr relative to the fresh monzogranite.The investigated granites contain basic xenoliths as well as pockets of pegmatites.Perthites,quartz,plagioclase and sometimes biotite,represent the essential constituents.Some accessory minerals like zircon are metamicted reflecting their radiogenic nature.The alkali granites are characterized by the presence of aegirine,rebeckite and arfvedsonite.Both syn-and post-orogenic granites show some variations in their bulk chemical compositions.The older granitoids are metaluminous and exhibit characteristics of I-type granites and possess an arc tectonic environment.On the other hand,the younger granites are peraluminous and exhibit the characteristics of post-collisional granites.It is interpreted that radioactivity of the studied rocks is mainly controlled by both magmatic and post-magmatic activities.Frequently,the post-orogenic granites host zoned and unzoned pegmatite pockets.Some of these pockets anomalously attain high radioactivity.The syenogranites and the pegmatites are characterized by high contents of SiO 2 and K 2 O and low CaO and MgO.They have transitional characters from highly fractionated calc-alkaline to alkaline.The alkali granites related to A2-subtype of A-type granites.The post-orogenic granites were originated from magma of dominant crustal source materials and related to post-collisional setting under extensional environment.
文摘This article is investigating analysis and chemical composition of ceramic pegmatite minerals obtained from the Terek deposit in Toktogul district of Kyrgyzstan. Several methods such as mineralogical studies, magnetic and gravitational enrichments, silicate and chemical analyses of ceramic pegmatite minerals, quartz-feldspathic concentrate and sludge removal have been performed for determination of pegmatite mineral applicability for production of porcelain and earthenware.
