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
The Jiuyishan granitic complex,located in the Nanling Range,South China,is composed of five granitic plutons(Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan).Zircon U-Pb dating of four plutons(Jinjiling,Pangxiemu,...The Jiuyishan granitic complex,located in the Nanling Range,South China,is composed of five granitic plutons(Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan).Zircon U-Pb dating of four plutons(Jinjiling,Pangxiemu,Shaziling and Xishan)yielded similar ages of approximately 153 Ma,indicating indistinguishable ages within error.Three plutons except the Shaziling pluton,have consistentε_(Nd)(t)(-7.8 to-5.8)andε_(Hf)(t)(-9.1 to-2.2)values,which are similar to those of the lower crustal granulitic metasedimentary and meta-igneous rocks in South China.Compared to other three plutons,the Shaziling pluton has consistentε_(Nd)(t)(-7.4 to-6.8)andε_(Hf)(t)(-7.5 to-4.7)values and shows similar source,but the Shaziling mafic microgranular enclaves(MMEs)show variableε_(Hf)(t)(-14.2 to 4.8)values,indicating a remarkable mantle magma injection of the Shaziling pluton.Zircon Ce/Sm-Yb/Gd,whole-rock CaO-P_(2)O_(5)and CaO-TiO_(2)linear trends reveal that from the Xishan to the Shaziling and from the Jinjiling to the Pangxiemu granites,they experienced apatite and titanite fractionation,respectively.Zircon Th,U,Nb,Ta,Hf,Ti,Y,P and rare earth element(REE)contents and whole-rock Sr,Ba and Rb contents also show that the Shaziling,Xishan,Jinjiling and Pangxiemu granites followed a discontinuous evolutionary series,but the Pangxiemu granites exhibit highly evolved nature.Four main controlling factors of W-Sn and rare metal mineralization in granitic rocks were discussed,and we found that the mineralization in Jiuyishan granitic complex was mainly controlled by the fractionation degree and crystallization temperature,but were rarely affected by oxygen fugacity and mantle material input.The Pangxiemu granites show particularly higher Rb and Ta contents than the other three plutons,implying that the ore deposits developed in the Jiuyishan Complex were directly related to the most evolved Pangxiemu pluton,with the occurrence of Rb and Ta as the most likely rare metal mineralization in the Jiuyishan District.A crystal mush model is proposed to interpret the petrogenetic and mineralizing processes of the Jiuyishan granitic complex.展开更多
Granite origin is crucial to understanding the evolution of continental crust,yet many concerns about granite genesis remain yielding ongoing debates.A new integrated study of petrology,geochronology,mineral chemistry...Granite origin is crucial to understanding the evolution of continental crust,yet many concerns about granite genesis remain yielding ongoing debates.A new integrated study of petrology,geochronology,mineral chemistry and whole-rock geochemistry of the Dupangling granitic complex in South China,indicate that the granites in the western complex were emplaced during the Caledonian(418 Ma);they have SiO_(2)contents of 68.1-70.4 wt%,and are calc-alkaline and strongly peraluminous with high maficity[(TFe_(2)O_(3)+MgO)>4.0 wt%]and exhibit^(87)Sr/^(86)Sr(t)of 0.7234-0.7311 andε_(Nd)(t)of-9.0 to-6.7.The granites in the eastern complex,emplaced during the Indosinian(212 Ma),have high SiO_(2)contents(73.3-79.8 wt%)and exhibit affinities with A-type granites,such as enrichment in alkalis and rare earth elements(REEs),and depletion in Sr and Ba along with high TFeO/(TFeO+MgO),Ga/Al and Zr+Y+Ce+Nb;these granites exhibit^(87)Sr/^(86)Sr(t)of 0.7221 andε_(Nd)(t)of-9.2 to-7.5.Geochemical characteristics suggest that the older Caledonian granites were derived through dehydration melting of Paleoproterozoic metasedimentary rocks plus additional(~20%-32%)input from mafic magma,whereas the Indosinian granites were generated through shallow dehydration melting of the Caledonian granitoids.展开更多
The Precambrian Homrit-Waggat granite is a post-orogenic batholithic intrusion located in the northern region of the Nubian Shield,characterized by a typical annular morphology and significant secondary alteration.Thi...The Precambrian Homrit-Waggat granite is a post-orogenic batholithic intrusion located in the northern region of the Nubian Shield,characterized by a typical annular morphology and significant secondary alteration.This study aims to elucidate the processes that have shaped the intrusion in both macroscopic and microscopic perspectives,employing a combination of field observation and petrographic analysis alongside major and trace element compositions of minerals.Within the central region of the pluton,biotite and amphibole are observed sporadically,while the predominant crystallization of anhydrous oligoclase in the outer regions has led to a progressive increase in volatile components within the residual melt,ultimately resulting in a volatile-saturated aluminosilicate melt.The exsolved fluids subsequently interacted with the previously crystallized mineral assemblage,producing metasomatic overprinting.As the cooling and crystallization continued,the water pressure within the magma chamber gradually escalated until it equaled or surpassed the confining pressure,leading to the formation of fractures and veins filled with minerals that crystallized from the residual aqueous fluids.The ongoing degassing and expulsion of aqueous fluids from the magma chamber’s interior ultimately contributed to the collapse of the chamber’s roof,resulting in the annular ring-dike morphology observed in the Homrit Waggat pluton.展开更多
Stable Sr isotopic composition(δ^(88/86)Sr)can be used to study magmatic processes,but their fractionation mechanism during magmatic evolution remains unclear.To understand the fractionation behaviors of the stable S...Stable Sr isotopic composition(δ^(88/86)Sr)can be used to study magmatic processes,but their fractionation mechanism during magmatic evolution remains unclear.To understand the fractionation behaviors of the stable Sr isotopes during magmatism,we report theδ^(88/86)Sr values of the Huili granitic pluton,which was subjected to intensive crystal-melt separation.The Huili pluton consists of K-feldspar granite and more evolved albite granite,and the albite granite exhibits significantly higherδ^(88/86)Sr values(+0.36‰to+0.52‰)than that of K-feldspar granite(+0.11‰to+0.25‰).K-feldspar,which contributes most of the Sr budget of the K-feldspar granite,has slightly lowerδ^(88/86)Sr values(−0.01‰to+0.17‰)than the whole rock.Theδ^(88/86)Sr variation of the Huili granites can be explained by separation of melt from K-feldspar-dominated crystals,because crystallization of K-feldspar can result in heavy Sr isotopic composition of the extracted interstitial melt.Stable Sr and Ba isotopic ratios in the Huili granites are highly coupled toward the heavy direction,refl ecting their similar element partitioning and isotope fractionation behaviors between the crystalline K-feldspar and melt.This study indicates that melt extraction plays a key role in granitic magma evolution.展开更多
Massive granitic rock avalanches are extensively developed in the middle section of the northern Qinling Mountains(NQM),China.The current consensus is that their formation could have been connected with seismic events...Massive granitic rock avalanches are extensively developed in the middle section of the northern Qinling Mountains(NQM),China.The current consensus is that their formation could have been connected with seismic events that occurred in the NQM.However,there is a lack of systematic discussion on the genetic dynamics of these rock avalanches.Hence,taking Earth system scientific research as a starting point,this paper systematically summarizes and discusses development characteristics,formation times and genetic dynamic mechanisms of granitic rock avalanches in the NQM based on geological investigations,high-precision remote sensing interpretations,geomorphological dating,geophysical exploration,and a large-scale shaking table model test.We identified 53 granitic rock avalanches in this area,with a single collapse area ranging from 0.01×10~6 to 1.71×10~6 m^(2).Their development time can be divided into six stages,namely,107000 years BP,11870–11950 years BP,11000 years BP,2300 years BP,1800 years BP,and 1500 years BP,which were closely related to multiple prehistoric or ancient earthquakes.We suggest that long-term coupling of internal and external earth dynamics was responsible for the granitic rock avalanches in the NQM;the internal dynamics were mainly related to subduction,collision and extrusion of different plates under the Qinling terrane,leading to the formation and tectonic uplift of the Qinling orogenic belt;and the external dynamics were closely associated with climate changes resulting in mountain denudation,freeze-thaw cycles and isostatic balance uplift.In this process,the formation and evolution of the Qinling orogenic belt play a geohazard-pregnant role,structural planes,including faults and joints,play a geohazard-controlled role,and earthquakes play a geohazard-induced role,which jointly results in the occurrence of large-scale granitic rock avalanches in the NQM.This research can not only decipher the genetic dynamic mechanism of large hard granitic rock avalanches but also reveal temporal and spatial patterns of the evolution of breeding and the generation of large-scale rock avalanches in the margins of orogenic belts.展开更多
Granite saprolite(GS)slope failure is a common yet catastrophic phenomenon in South China.Although the impact of subtropical climate,characterized by high temperatures and heavy rainfall,is widely recognized,the effec...Granite saprolite(GS)slope failure is a common yet catastrophic phenomenon in South China.Although the impact of subtropical climate,characterized by high temperatures and heavy rainfall,is widely recognized,the effect of the capillary imbibition and drying(CID)process,which frequently occurs during the dry season,on the hydro-mechanical properties of GS and slope stability is largely overlooked.This research examines natural GS specimens with various degrees of weathering subjected to CID cycles.The study investigates the capillary imbibition(CI)process and the evolution of the soil's hydromechanical properties across CID cycles.The results indicate that the CI process in GS is fundamentally different from that in clays and sands.The aggregated structure of GS comprising numerous fissures and large pores plays a critical role.In addition,the CID cycles cause the hydro-mechanical degradation of GS,including a finer particle composition,decreased shear strength,and increased permeability and disintegration potential,where damage to soil cementation and fissure development are identified as critical factors.This investigation reveals new insights into the mechanical properties of GS that are essential for the development of effective landslide management strategies in South China.展开更多
Dabie-type porphyry Mo deposits were proposed as a new type of porphyry Mo deposits,and had unique geological characteristics.It is still poorly understood about the magmatic processes that led to the Dabie-type Mo mi...Dabie-type porphyry Mo deposits were proposed as a new type of porphyry Mo deposits,and had unique geological characteristics.It is still poorly understood about the magmatic processes that led to the Dabie-type Mo mineralization.Here,we present zircon U-Pb and Lu-Hf isotopic,whole-rock and biotite elemental,and whole-rock Sr-Nd isotopic analyses on the Lingshan granitic batholith in the Dabie Orogen.It consists of three units(ⅠtoⅢ)that were emplaced before,genetically accompanied with,and after the Mo mineralization.LA-ICP-MS zircon U-Pb dating yielded crystallization ages of 128.2±1.0 Ma(MSWD=1.14)for UnitⅠand ages of 127.8±1.2 Ma(MSWD=0.28)and 126.6±1.8 Ma(MSWD=1.6)for UnitⅡ,indicating that they were emplaced during 130 to 125 Ma.The granites have high SiO_(2)contents(75.84 wt.%to 78.94 wt.%)and low MgO contents(0.07 wt.%to 0.10 wt.%),and are classified as fractionatedⅠ-type granite.UnitsⅠandⅡhave similar Sr-Nd isotopic ratios(ε_(Nd)(t)=-16.2 to-17.2,(^(87)Sr/^(86)Sr)_(i)=0.70540 to 0.70692)and zirconε_(Hf)(t)values(-17.4 to-20.4),indicating they were derived from partial melting of the ancient Yangtze lower crust.Mo mineralized granite from UnitⅡis characterized by the lower oxygen fugacity,fluorine enrichment and high fractionation.Magmas of unitsⅠandⅡhave experienced fractional crystallization,with the assimilation of supracrustal materials that account for the increased TiO_(2),F and Mo contents,and the decreased fO_(2).We proposed that the assimilation in upper-crustal magmatic processes plays key factors for magmatic systems that led to the Dabie-type porphyry Mo deposits.展开更多
Regolith,widely distributed on the Earth’s surface,constitutes a significant compartment of the Critical Zone,resulting from intricate interactions among the atmosphere,lithosphere,hydrosphere,and biosphere.Regolith ...Regolith,widely distributed on the Earth’s surface,constitutes a significant compartment of the Critical Zone,resulting from intricate interactions among the atmosphere,lithosphere,hydrosphere,and biosphere.Regolith formation critically influences nutrient release,soil production,and long-term climate regulation.Regolith development is governed by two primary processes:production and denudation.An urgent need exists to comprehensively understand these processes to refine our understanding of Critical Zone functions.This study investigates an in-situ regolith profile developed on granitic bedrock from a tropical region(Sanya,China).We conducted geochemical analyses,encompassing major,trace elements and mineralogical compositions as well as U-series isotopes,and applied the U-series disequilibrium method to investigate the formation history of this profile.Alternatively,dividing the regolith profile into sub-weathering zones provides a better explanation for the geochemical results,and a multi-stage model based on this subdivision effectively interprets the evolution of deep regolith.Utilizing this multi-stage model,regolith production rates is derived from the“gain and loss”model,ranging from 1.27±0.03 to 42.42±24.24 m/Ma.The production rates first increase from surface until a maximum rate is reached at the depth of∼160 cm and then decrease at further deeper horizons along the depth profile,and the variation of production rates follows a so-called“humped function”.This pioneering investigation into regolith production rates in the Chinese tropical region indicates that(1)the studied profile deviates from a steady state compared to the denudation rate derived from cosmogenic nuclides(^(10)Be_in-situ);(2)subdividing the deep profile based on geochemical data and U-series isotopic activity ratios is imperative for accurately determining regolith production rates;and(3)the combination of U-series disequilibrium and cosmogenic nuclides robustly evaluates the quantitative evolution state of regolith over long time scales.展开更多
Recently,Danziger et al.(2024)published a discussion on our paper(Zhang et al.,2023).In the discussed paper,seismic piezocone tests were conducted to characterize a granitic weathering profile.Pore pressure was measur...Recently,Danziger et al.(2024)published a discussion on our paper(Zhang et al.,2023).In the discussed paper,seismic piezocone tests were conducted to characterize a granitic weathering profile.Pore pressure was measured at both the cone mid-face and the shoulder.The effects of penetrometer size and penetration rate were considered.The results of the study were presented as several updated soil behavior charts.In this reply,the issues raised during the discussion are addressed,including the geotechnical behavior and laboratory and in situ tests of weathered granite.The constructive feedback from the discussers not only enriches the research works of the studied soils but also enhances the understanding of weathering geomaterials.展开更多
Composite granitic pluton with distinct units is a potential target for identifying its detailed magma evolution.Here,we present zircon U-Pb ages and Hf isotope,whole-rock major and trace element compositions and Nd-P...Composite granitic pluton with distinct units is a potential target for identifying its detailed magma evolution.Here,we present zircon U-Pb ages and Hf isotope,whole-rock major and trace element compositions and Nd-Pb isotopes of the Wangxiang composite pluton,South China.New ages obtained show that these rocks were generated in Late Jurassic(ca.156–158 Ma).The rocks are divided into low silica(SiO_(2)<67 wt.%,biotite granodiorites and their dioritic enclaves)and high silica ones(SiO_(2)>71 wt.%,two-mica granites,garnet-bearing muscovite granites and muscovite granites).The high silica rocks are enriched in light rare earth elements(LREEs)relative to heavy REEs(HREEs)((La/Yb)_(N)=15.6–41.9,while the low silica rocks are not(0.7–76.6).All rocks show various negative Ti,Sr,Eu and strong positive Pb anomalies.The low silica rocks have less negative values ofε_(Nd)(t)(-8.79 to-6.99),similar values of~((206)Pb/^(204)Pb)_(i)(18.155–18.346)andε_(Hf)(t)(-9.51 to-3.47,except one-12.84),compared to the high silica rocks(ε_(Nd)(t)=-11.14 to-10.26;^((206)Pb/^(204)Pb)_(i)=17.935–19.093;ε_(Hf)(t)=-12.03 to-7.15,except one-2.41).Data suggest that the parental magma of the studied rocks(represented by enclaves)was produced by partial melting of a garnet-free crustal source.Subsequently those crustal magmas formed the more evolved units through assimilation and fractional crystallization processes,and fluid enrichment during the final magmatic activity.Combining our results with previous multidisciplinary studies,we propose that the key factor to control the evolution of Wangxiang composite pluton is discrete emplacement of crustal magmas by dyking.展开更多
The deep geologic processes between the Xing’an-Mongolian Orogenic Belt and the North China Craton in the Mesozoic are crucial to reveal the magmatic and tectonic evolution and their constraints on mineralization in ...The deep geologic processes between the Xing’an-Mongolian Orogenic Belt and the North China Craton in the Mesozoic are crucial to reveal the magmatic and tectonic evolution and their constraints on mineralization in the Jiapigou-Haigou collage zone.In this paper,We have presented the geochronology,geochemistry and Sr-Nd-Hf isotopic compositions of the Middle Jurassic granitic complexes in the Songjianghe area,Jilin Province.The granitic complexes can be categorized into four groups based on their geologic characteristics,with corresponding zircon U-Pb isotope ages of 177 Ma,172 Ma,169 Ma and 168-167 Ma,respectively.These granitoids exhibit calcalkaline to high-K calc-alkaline,metaluminous to weakly peraluminous Ⅰ-type characteristics,which show relative enrichment in LILEs(Rb,Sr,Ba)and depletion in HFSEs(Nb,Zr).Geochemical analyses reveal high initial^(87)Sr/^(86)Sr ratios of 0.70633-0.70740,coupled with lowεNd(t)values ranging from−10.65 to−13.23.The zircon analyses show similarly negativeεHf(t)values ranging from−16.9 to−3.2.The integrated elemental and Hf-Sr-Nd isotopic signatures demonstrate that the primitive magmas of the four group rocks were primarily derived from partial melting of thickened Archean lower crust,with the exception of the Group Ⅳ rocks,which exhibit significant evidence of crustal contamination.The residual mineral assemblages during the magma-forming process varied from amphibole to eclogite facies.These findings indicate that magmatism in the Songjianghe region likely resulted from the accretion and delamination of the Archean crust in the collage zone during the subduction of the Paleo-Pacific Plate beneath the Eurasian continent.展开更多
Homret Ghannam alkali feldspar granite(HGAFG)in the central Eastern Desert(CED)of Egypt represents a distinctive example of late Neoproterozoic magmatism in the Arabian-Nubian Shield(ANS).This study integrates field o...Homret Ghannam alkali feldspar granite(HGAFG)in the central Eastern Desert(CED)of Egypt represents a distinctive example of late Neoproterozoic magmatism in the Arabian-Nubian Shield(ANS).This study integrates field observations,petrography,mineral chemistry(EMPA),and whole-rock geochemistry to investigate its petrogenesis,geodynamic evolution,and rare-metal potential.HGAFG comprises two cogenetic varieties,alkali feldspar granite and riebeckite-bearing granite,hosting rare-metal minerals such as zircon,fluorite,columbite and apatite.HGAFG exhibits diagnostic A-type geochemical characteristics,including high SiO₂contents(73.81-77.86 wt%),metaluminous to mildly peralkaline composition(ASI:0.92-1.03),enrichment in HFSE(Zr≈791.80 ppm,Nb≈68.12 ppm,Y≈90.81 ppm)andΣREE(103.40-475.57 ppm),and pronounced negative Eu anomalies(Eu/Eu^(*)=0.07-0.20).Zircon saturation thermometry yields high crystallization temperatures(TZr≈908.87℃)and low emplacement pressures(1.46 kbar)under reducing conditions(ƒO_(2)≈−11.5).The mineralogical and geochemical results reveal that HGAFG originated from a hybrid,fluorine-rich magma generated by anatexis of lower crust,followed by extensive fractional crystallization,during late post-collisional extension associated with lithospheric delamination.The reduced nature and fluorine enrichment of HGAFG magma promoted the mineralization of Nb-Ta-REE phases,highlighting its significance as a fertile,high-temperature product of the terminal magmatic stage in ANS evolution.展开更多
The Mianhuakeng uranium deposit,characterized by uranium-rich granite,serves as a key site for research into crustal radioactive heating.Based on 45 rock samples,this study reviews that the host granite in the Mianhua...The Mianhuakeng uranium deposit,characterized by uranium-rich granite,serves as a key site for research into crustal radioactive heating.Based on 45 rock samples,this study reviews that the host granite in the Mianhuakeng uranium deposit has a high radioactive heat production rate(avg.5.50μW/m³)and a low Th/U ratio(avg.2.62).Uranium-rich granite and its alteration zone within the upper crust(0-5 km depth)contribute about 45%of the total radioactive heat production,wich is crucial for controlling geothermal resource distribution.For uranium-thermal at tectonic plate margins,a symbiotic geological model was proposed:Firstly,subduction of the Pacific Plate caused upwelling of the asthenosphere,generating a high heat-flow background.Secondly,heat transfer is enhanced by major faults such as the Youdong and Mianhuakeng faults.Subsequently,uranium was mobilized,transported,and enriched within the granite through deep siliceous hydrothermal activity and associated alteration.Ultimately,the uranium enrichment in granite leads to increased radioactive heat production,resulting in local thermal anomalies.This model provides a theoretical support for exploring and developing uranium-thermal symbiotic resources in South China.展开更多
Strategic emerging minerals such as lithium,beryllium,niobium and tantalum are the most important rare metals currently,especially with the increasing demand of emerging industries on rare metals in China.The Jiajika ...Strategic emerging minerals such as lithium,beryllium,niobium and tantalum are the most important rare metals currently,especially with the increasing demand of emerging industries on rare metals in China.The Jiajika deposit with a complete Li-Be-Nb-Ta metallogenic series is the largest pegmatite type rare metal deposit in China at present.In this paper,systematic researches of geochronology and petrogeochemistry were carried out to understand the genetic relationships between mineralization and magma evolution in the Jiajika deposit,which might be helpful to further rare-element prospecting in Songpan-Garze area.Zircon LA-ICP-MS U-Pb dating yields a concordia age of 217±1.1 Ma and a weighted mean 206 Pb/238 U age of 217±0.84 Ma for the aplite from the No.308 pegmatite.Cassiterite LA-MC-ICPMS dating yields concordant ages of 211±4.6 Ma for the No.308 pegmatite vein and198±4.4 Ma for the No.133 pegmatite vein,indicating that the rare metal mineralization mainly occurred in the Late Indosinian Period,further suggesting that the granites,aplites and pegmatites in Jiajika formed during a relatively stable stage after the intense orogeny of the Indosinian cycle.The rare metal-bearing granitic rocks and pegmatites show a clear linear relationship between A/CNK and A/NK and are enriched in total alkalis and depleted in CaO,FeO,MnO,MgO,Ba and Sr.All barren rocks and mineralized rocks feature similar rare earth element and trace element geochemical patterns.Thus,these characteristics indicate that the aplites and pegmatites represent the highly differentiated products of the two-mica granite(MaG)in this area,which is the most likely parent magma.During the evolution of magma,strong alkali metasomatism occurred between the melt phase and the volatile-rich fluid phase;as a result,large-scale rare metal mineralization occurred in certain structural zones of the pegmatite veins in the Jiajika deposit.展开更多
The granitic gneisses from the ultrahigh-pressure (UHP) metamorphic terrain of the southeastern Dabie Mountains encompass two types: monzonitic granitic gneiss and alkali-feldspar granitic gneiss, which are characteri...The granitic gneisses from the ultrahigh-pressure (UHP) metamorphic terrain of the southeastern Dabie Mountains encompass two types: monzonitic granitic gneiss and alkali-feldspar granitic gneiss, which are characterized by rich alkalis, poor CaO, high FeO/MgO, particularly high Ba, Rb, Th, Ta, REE (except Eu), Ga, Nb and Zn, and low Sr, Eu, Cr, Co and Ni. The gneisses, particularly the alkali-feldspar granitic gneiss, have typical chemical characteristics of A-type granites. They resulted from partial melting of crustal materials existing in the rift zone along the northern margin of the South China block during the Neoproterozoic. These gneisses might not have undergone UHP metamorphism during the late Triassic, but were involved into UHP rocks by the tectonic mixing process and kept the exhumation message of the UHP rocks from the middle and upper crust.展开更多
We report for the first time the geochemistry of rare earth elements（REE） in the weathered crusts of I-type and calc-alkaline to high-K（shoshonitic） granitic rocks at Mamasa and Palu region, Sulawesi Island, Indon...We report for the first time the geochemistry of rare earth elements（REE） in the weathered crusts of I-type and calc-alkaline to high-K（shoshonitic） granitic rocks at Mamasa and Palu region, Sulawesi Island, Indonesia. The weathered crusts can be divided into horizon A（lateritic profile） and B（weathered horizon）. Quartz, albite, kaolinite, halloysite and montmorrilonite prevail in the weathered crust. Both weathered profiles show that the total REE increased from the parent rocks to the horizon B but significantly decrease toward the upper part（horizon A）. LREE are enriched toward the upper part of the profile as shown by La/YbN value. However, HREE concentrations are high in horizon B1 in Palu profile. The total REE content of the weathered crust are relatively elevated compared to the parent rocks, particularly in the lower part of horizon B in Mamasa profile and in horizon B2 in Palu profile. This suggests that REE-bearing accessory minerals may be resistant against weathering and may remain as residual phase in the weathered crusts. The normalized isocon diagram shows that the mass balance of major and REE components between each horizon in Mamasa and Palu weathering profile are different. The positive Ce anomaly in the horizon A of Mamasa profile indicated that Ce is rapidly precipitated during weathering and retain at the upper soil horizon.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
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
The LA-ICPMS zircon U-Pb geochronology of three typically Indosinian granitic plutons yielded weighted mean ^206pb/^238U ages of 214.1±5.9 Ma and 210.3±4.7 Ma for the biotite monzonitic granites from the Xie...The LA-ICPMS zircon U-Pb geochronology of three typically Indosinian granitic plutons yielded weighted mean ^206pb/^238U ages of 214.1±5.9 Ma and 210.3±4.7 Ma for the biotite monzonitic granites from the Xiema and Xiangzikou plutons in Hunan Province, and 205.3±1.6 Ma for biotite granite from the Napeng pluton, western Guandong Province, respectively, showing a similar late Indosinian age of crystallization. In combination with other geochronological data from Indosinian granites within the South China Block （SCB）, it is proposed that those late Indosinian granites with an age of -210 Ma and the early Indosinian granites （230-245 Ma） have the similar petrogenesis in identical tectonic setting. The Indosinian granites within the SCB might be the products of anatexis of the thickening crust in a compressive regime. These data provide a further understanding for the temporal and spatial distribution of the Indosinian granites and the dynamic evolution of the SCB.展开更多
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financially supported by the Provincial Natural Science Foundation of Hunan(Nos.2019JJ50831,2023JJ30505 and 2023JJ40541)the China Postdoctoral Science Foundation(Nos.2017M622597 and 2021M690591)+2 种基金the Open Research Fund Program of Fundamental Science on Radioactive Geology and Exploration Technology Laboratory(East China University of Technology)(No.2022RGET04)the National Foreign Expert Project(No.G2022029012L)the National Nature Science Foundation of China(No.41002022)。
文摘The Jiuyishan granitic complex,located in the Nanling Range,South China,is composed of five granitic plutons(Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan).Zircon U-Pb dating of four plutons(Jinjiling,Pangxiemu,Shaziling and Xishan)yielded similar ages of approximately 153 Ma,indicating indistinguishable ages within error.Three plutons except the Shaziling pluton,have consistentε_(Nd)(t)(-7.8 to-5.8)andε_(Hf)(t)(-9.1 to-2.2)values,which are similar to those of the lower crustal granulitic metasedimentary and meta-igneous rocks in South China.Compared to other three plutons,the Shaziling pluton has consistentε_(Nd)(t)(-7.4 to-6.8)andε_(Hf)(t)(-7.5 to-4.7)values and shows similar source,but the Shaziling mafic microgranular enclaves(MMEs)show variableε_(Hf)(t)(-14.2 to 4.8)values,indicating a remarkable mantle magma injection of the Shaziling pluton.Zircon Ce/Sm-Yb/Gd,whole-rock CaO-P_(2)O_(5)and CaO-TiO_(2)linear trends reveal that from the Xishan to the Shaziling and from the Jinjiling to the Pangxiemu granites,they experienced apatite and titanite fractionation,respectively.Zircon Th,U,Nb,Ta,Hf,Ti,Y,P and rare earth element(REE)contents and whole-rock Sr,Ba and Rb contents also show that the Shaziling,Xishan,Jinjiling and Pangxiemu granites followed a discontinuous evolutionary series,but the Pangxiemu granites exhibit highly evolved nature.Four main controlling factors of W-Sn and rare metal mineralization in granitic rocks were discussed,and we found that the mineralization in Jiuyishan granitic complex was mainly controlled by the fractionation degree and crystallization temperature,but were rarely affected by oxygen fugacity and mantle material input.The Pangxiemu granites show particularly higher Rb and Ta contents than the other three plutons,implying that the ore deposits developed in the Jiuyishan Complex were directly related to the most evolved Pangxiemu pluton,with the occurrence of Rb and Ta as the most likely rare metal mineralization in the Jiuyishan District.A crystal mush model is proposed to interpret the petrogenetic and mineralizing processes of the Jiuyishan granitic complex.
基金supported financially by the National Natural Science Foundation of China(Grant Nos.41872054 and 41272083)。
文摘Granite origin is crucial to understanding the evolution of continental crust,yet many concerns about granite genesis remain yielding ongoing debates.A new integrated study of petrology,geochronology,mineral chemistry and whole-rock geochemistry of the Dupangling granitic complex in South China,indicate that the granites in the western complex were emplaced during the Caledonian(418 Ma);they have SiO_(2)contents of 68.1-70.4 wt%,and are calc-alkaline and strongly peraluminous with high maficity[(TFe_(2)O_(3)+MgO)>4.0 wt%]and exhibit^(87)Sr/^(86)Sr(t)of 0.7234-0.7311 andε_(Nd)(t)of-9.0 to-6.7.The granites in the eastern complex,emplaced during the Indosinian(212 Ma),have high SiO_(2)contents(73.3-79.8 wt%)and exhibit affinities with A-type granites,such as enrichment in alkalis and rare earth elements(REEs),and depletion in Sr and Ba along with high TFeO/(TFeO+MgO),Ga/Al and Zr+Y+Ce+Nb;these granites exhibit^(87)Sr/^(86)Sr(t)of 0.7221 andε_(Nd)(t)of-9.2 to-7.5.Geochemical characteristics suggest that the older Caledonian granites were derived through dehydration melting of Paleoproterozoic metasedimentary rocks plus additional(~20%-32%)input from mafic magma,whereas the Indosinian granites were generated through shallow dehydration melting of the Caledonian granitoids.
基金supported by Science and Technology Development Fund(STDF)of the Arab Republic of Egypt(No.23080)entitled―Rare Metal Ore Deposits in Egypt:A comparative survey in altered granites from selected areas in the Central Eastern Desert‖(to M.A.ABU EL-RUS)National Key Research and Development Program of China(No.2023YFF0804200).
文摘The Precambrian Homrit-Waggat granite is a post-orogenic batholithic intrusion located in the northern region of the Nubian Shield,characterized by a typical annular morphology and significant secondary alteration.This study aims to elucidate the processes that have shaped the intrusion in both macroscopic and microscopic perspectives,employing a combination of field observation and petrographic analysis alongside major and trace element compositions of minerals.Within the central region of the pluton,biotite and amphibole are observed sporadically,while the predominant crystallization of anhydrous oligoclase in the outer regions has led to a progressive increase in volatile components within the residual melt,ultimately resulting in a volatile-saturated aluminosilicate melt.The exsolved fluids subsequently interacted with the previously crystallized mineral assemblage,producing metasomatic overprinting.As the cooling and crystallization continued,the water pressure within the magma chamber gradually escalated until it equaled or surpassed the confining pressure,leading to the formation of fractures and veins filled with minerals that crystallized from the residual aqueous fluids.The ongoing degassing and expulsion of aqueous fluids from the magma chamber’s interior ultimately contributed to the collapse of the chamber’s roof,resulting in the annular ring-dike morphology observed in the Homrit Waggat pluton.
基金supported by National Natural Science Foundation of China(42473009).
文摘Stable Sr isotopic composition(δ^(88/86)Sr)can be used to study magmatic processes,but their fractionation mechanism during magmatic evolution remains unclear.To understand the fractionation behaviors of the stable Sr isotopes during magmatism,we report theδ^(88/86)Sr values of the Huili granitic pluton,which was subjected to intensive crystal-melt separation.The Huili pluton consists of K-feldspar granite and more evolved albite granite,and the albite granite exhibits significantly higherδ^(88/86)Sr values(+0.36‰to+0.52‰)than that of K-feldspar granite(+0.11‰to+0.25‰).K-feldspar,which contributes most of the Sr budget of the K-feldspar granite,has slightly lowerδ^(88/86)Sr values(−0.01‰to+0.17‰)than the whole rock.Theδ^(88/86)Sr variation of the Huili granites can be explained by separation of melt from K-feldspar-dominated crystals,because crystallization of K-feldspar can result in heavy Sr isotopic composition of the extracted interstitial melt.Stable Sr and Ba isotopic ratios in the Huili granites are highly coupled toward the heavy direction,refl ecting their similar element partitioning and isotope fractionation behaviors between the crystalline K-feldspar and melt.This study indicates that melt extraction plays a key role in granitic magma evolution.
基金financially supported by the National Natural Science Foundation of China(Nos.42207197,42293355,41672285,42293350,42341101)the Fundamental Research Funds for the Central Universities(Nos.300102264917,300102262908,590123008)。
文摘Massive granitic rock avalanches are extensively developed in the middle section of the northern Qinling Mountains(NQM),China.The current consensus is that their formation could have been connected with seismic events that occurred in the NQM.However,there is a lack of systematic discussion on the genetic dynamics of these rock avalanches.Hence,taking Earth system scientific research as a starting point,this paper systematically summarizes and discusses development characteristics,formation times and genetic dynamic mechanisms of granitic rock avalanches in the NQM based on geological investigations,high-precision remote sensing interpretations,geomorphological dating,geophysical exploration,and a large-scale shaking table model test.We identified 53 granitic rock avalanches in this area,with a single collapse area ranging from 0.01×10~6 to 1.71×10~6 m^(2).Their development time can be divided into six stages,namely,107000 years BP,11870–11950 years BP,11000 years BP,2300 years BP,1800 years BP,and 1500 years BP,which were closely related to multiple prehistoric or ancient earthquakes.We suggest that long-term coupling of internal and external earth dynamics was responsible for the granitic rock avalanches in the NQM;the internal dynamics were mainly related to subduction,collision and extrusion of different plates under the Qinling terrane,leading to the formation and tectonic uplift of the Qinling orogenic belt;and the external dynamics were closely associated with climate changes resulting in mountain denudation,freeze-thaw cycles and isostatic balance uplift.In this process,the formation and evolution of the Qinling orogenic belt play a geohazard-pregnant role,structural planes,including faults and joints,play a geohazard-controlled role,and earthquakes play a geohazard-induced role,which jointly results in the occurrence of large-scale granitic rock avalanches in the NQM.This research can not only decipher the genetic dynamic mechanism of large hard granitic rock avalanches but also reveal temporal and spatial patterns of the evolution of breeding and the generation of large-scale rock avalanches in the margins of orogenic belts.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42307212 and 42177148)the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.SKLGME023005).
文摘Granite saprolite(GS)slope failure is a common yet catastrophic phenomenon in South China.Although the impact of subtropical climate,characterized by high temperatures and heavy rainfall,is widely recognized,the effect of the capillary imbibition and drying(CID)process,which frequently occurs during the dry season,on the hydro-mechanical properties of GS and slope stability is largely overlooked.This research examines natural GS specimens with various degrees of weathering subjected to CID cycles.The study investigates the capillary imbibition(CI)process and the evolution of the soil's hydromechanical properties across CID cycles.The results indicate that the CI process in GS is fundamentally different from that in clays and sands.The aggregated structure of GS comprising numerous fissures and large pores plays a critical role.In addition,the CID cycles cause the hydro-mechanical degradation of GS,including a finer particle composition,decreased shear strength,and increased permeability and disintegration potential,where damage to soil cementation and fissure development are identified as critical factors.This investigation reveals new insights into the mechanical properties of GS that are essential for the development of effective landslide management strategies in South China.
基金supported by the National Science and Technology Major Project(No.2024ZD1001005)the National Natural Science Foundation of China(No.42172103)+2 种基金the Natural Science Foundation of Hubei Province(Nos.2023AFD206,2024AFD401,2025AFD439,2025AFD452)the Research Fund Program of Hubei Key Laboratory of Resources and Eco-Environment Geology(Nos.HBREGKFJJ-202302,HBREGKFJJ-202402)the State Key Laboratory of Geological Processes and Mineral Resources(No.GPMR202424)。
文摘Dabie-type porphyry Mo deposits were proposed as a new type of porphyry Mo deposits,and had unique geological characteristics.It is still poorly understood about the magmatic processes that led to the Dabie-type Mo mineralization.Here,we present zircon U-Pb and Lu-Hf isotopic,whole-rock and biotite elemental,and whole-rock Sr-Nd isotopic analyses on the Lingshan granitic batholith in the Dabie Orogen.It consists of three units(ⅠtoⅢ)that were emplaced before,genetically accompanied with,and after the Mo mineralization.LA-ICP-MS zircon U-Pb dating yielded crystallization ages of 128.2±1.0 Ma(MSWD=1.14)for UnitⅠand ages of 127.8±1.2 Ma(MSWD=0.28)and 126.6±1.8 Ma(MSWD=1.6)for UnitⅡ,indicating that they were emplaced during 130 to 125 Ma.The granites have high SiO_(2)contents(75.84 wt.%to 78.94 wt.%)and low MgO contents(0.07 wt.%to 0.10 wt.%),and are classified as fractionatedⅠ-type granite.UnitsⅠandⅡhave similar Sr-Nd isotopic ratios(ε_(Nd)(t)=-16.2 to-17.2,(^(87)Sr/^(86)Sr)_(i)=0.70540 to 0.70692)and zirconε_(Hf)(t)values(-17.4 to-20.4),indicating they were derived from partial melting of the ancient Yangtze lower crust.Mo mineralized granite from UnitⅡis characterized by the lower oxygen fugacity,fluorine enrichment and high fractionation.Magmas of unitsⅠandⅡhave experienced fractional crystallization,with the assimilation of supracrustal materials that account for the increased TiO_(2),F and Mo contents,and the decreased fO_(2).We proposed that the assimilation in upper-crustal magmatic processes plays key factors for magmatic systems that led to the Dabie-type porphyry Mo deposits.
基金supported by The National Natural Science Foundation of China(42303060)The China Scholarship Council(CSC,201906250131).
文摘Regolith,widely distributed on the Earth’s surface,constitutes a significant compartment of the Critical Zone,resulting from intricate interactions among the atmosphere,lithosphere,hydrosphere,and biosphere.Regolith formation critically influences nutrient release,soil production,and long-term climate regulation.Regolith development is governed by two primary processes:production and denudation.An urgent need exists to comprehensively understand these processes to refine our understanding of Critical Zone functions.This study investigates an in-situ regolith profile developed on granitic bedrock from a tropical region(Sanya,China).We conducted geochemical analyses,encompassing major,trace elements and mineralogical compositions as well as U-series isotopes,and applied the U-series disequilibrium method to investigate the formation history of this profile.Alternatively,dividing the regolith profile into sub-weathering zones provides a better explanation for the geochemical results,and a multi-stage model based on this subdivision effectively interprets the evolution of deep regolith.Utilizing this multi-stage model,regolith production rates is derived from the“gain and loss”model,ranging from 1.27±0.03 to 42.42±24.24 m/Ma.The production rates first increase from surface until a maximum rate is reached at the depth of∼160 cm and then decrease at further deeper horizons along the depth profile,and the variation of production rates follows a so-called“humped function”.This pioneering investigation into regolith production rates in the Chinese tropical region indicates that(1)the studied profile deviates from a steady state compared to the denudation rate derived from cosmogenic nuclides(^(10)Be_in-situ);(2)subdividing the deep profile based on geochemical data and U-series isotopic activity ratios is imperative for accurately determining regolith production rates;and(3)the combination of U-series disequilibrium and cosmogenic nuclides robustly evaluates the quantitative evolution state of regolith over long time scales.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42307212 and 42177148)the Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.SKLGME-JBGS2403)。
文摘Recently,Danziger et al.(2024)published a discussion on our paper(Zhang et al.,2023).In the discussed paper,seismic piezocone tests were conducted to characterize a granitic weathering profile.Pore pressure was measured at both the cone mid-face and the shoulder.The effects of penetrometer size and penetration rate were considered.The results of the study were presented as several updated soil behavior charts.In this reply,the issues raised during the discussion are addressed,including the geotechnical behavior and laboratory and in situ tests of weathered granite.The constructive feedback from the discussers not only enriches the research works of the studied soils but also enhances the understanding of weathering geomaterials.
基金provided by the National Natural Science Foundation of China(No.41002022)the National Key R&D Program of China(No.2017YFC0602402)+3 种基金the Provincial Natural Science Foundation of Hunan(No.2019JJ50831)the Opening Foundation of State Key Laboratory of Continental Dynamics,Northwest University(No.20LCD08)the Funded by Open Research Fund Programme of the Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education(No.2018YSJS07)Bruna B.Carvalho is thankful to MIUR(Ministero dell’Istruzione,dell’Universitàe della Ricerca)for the award of a grant(No.PNRA18_00103)。
文摘Composite granitic pluton with distinct units is a potential target for identifying its detailed magma evolution.Here,we present zircon U-Pb ages and Hf isotope,whole-rock major and trace element compositions and Nd-Pb isotopes of the Wangxiang composite pluton,South China.New ages obtained show that these rocks were generated in Late Jurassic(ca.156–158 Ma).The rocks are divided into low silica(SiO_(2)<67 wt.%,biotite granodiorites and their dioritic enclaves)and high silica ones(SiO_(2)>71 wt.%,two-mica granites,garnet-bearing muscovite granites and muscovite granites).The high silica rocks are enriched in light rare earth elements(LREEs)relative to heavy REEs(HREEs)((La/Yb)_(N)=15.6–41.9,while the low silica rocks are not(0.7–76.6).All rocks show various negative Ti,Sr,Eu and strong positive Pb anomalies.The low silica rocks have less negative values ofε_(Nd)(t)(-8.79 to-6.99),similar values of~((206)Pb/^(204)Pb)_(i)(18.155–18.346)andε_(Hf)(t)(-9.51 to-3.47,except one-12.84),compared to the high silica rocks(ε_(Nd)(t)=-11.14 to-10.26;^((206)Pb/^(204)Pb)_(i)=17.935–19.093;ε_(Hf)(t)=-12.03 to-7.15,except one-2.41).Data suggest that the parental magma of the studied rocks(represented by enclaves)was produced by partial melting of a garnet-free crustal source.Subsequently those crustal magmas formed the more evolved units through assimilation and fractional crystallization processes,and fluid enrichment during the final magmatic activity.Combining our results with previous multidisciplinary studies,we propose that the key factor to control the evolution of Wangxiang composite pluton is discrete emplacement of crustal magmas by dyking.
基金supported by the Natural Science Foundation of Jilin Province of China(grant no.20230101075JC)the National Natural Science Foundation of China(grant no.42072085).
文摘The deep geologic processes between the Xing’an-Mongolian Orogenic Belt and the North China Craton in the Mesozoic are crucial to reveal the magmatic and tectonic evolution and their constraints on mineralization in the Jiapigou-Haigou collage zone.In this paper,We have presented the geochronology,geochemistry and Sr-Nd-Hf isotopic compositions of the Middle Jurassic granitic complexes in the Songjianghe area,Jilin Province.The granitic complexes can be categorized into four groups based on their geologic characteristics,with corresponding zircon U-Pb isotope ages of 177 Ma,172 Ma,169 Ma and 168-167 Ma,respectively.These granitoids exhibit calcalkaline to high-K calc-alkaline,metaluminous to weakly peraluminous Ⅰ-type characteristics,which show relative enrichment in LILEs(Rb,Sr,Ba)and depletion in HFSEs(Nb,Zr).Geochemical analyses reveal high initial^(87)Sr/^(86)Sr ratios of 0.70633-0.70740,coupled with lowεNd(t)values ranging from−10.65 to−13.23.The zircon analyses show similarly negativeεHf(t)values ranging from−16.9 to−3.2.The integrated elemental and Hf-Sr-Nd isotopic signatures demonstrate that the primitive magmas of the four group rocks were primarily derived from partial melting of thickened Archean lower crust,with the exception of the Group Ⅳ rocks,which exhibit significant evidence of crustal contamination.The residual mineral assemblages during the magma-forming process varied from amphibole to eclogite facies.These findings indicate that magmatism in the Songjianghe region likely resulted from the accretion and delamination of the Archean crust in the collage zone during the subduction of the Paleo-Pacific Plate beneath the Eurasian continent.
文摘Homret Ghannam alkali feldspar granite(HGAFG)in the central Eastern Desert(CED)of Egypt represents a distinctive example of late Neoproterozoic magmatism in the Arabian-Nubian Shield(ANS).This study integrates field observations,petrography,mineral chemistry(EMPA),and whole-rock geochemistry to investigate its petrogenesis,geodynamic evolution,and rare-metal potential.HGAFG comprises two cogenetic varieties,alkali feldspar granite and riebeckite-bearing granite,hosting rare-metal minerals such as zircon,fluorite,columbite and apatite.HGAFG exhibits diagnostic A-type geochemical characteristics,including high SiO₂contents(73.81-77.86 wt%),metaluminous to mildly peralkaline composition(ASI:0.92-1.03),enrichment in HFSE(Zr≈791.80 ppm,Nb≈68.12 ppm,Y≈90.81 ppm)andΣREE(103.40-475.57 ppm),and pronounced negative Eu anomalies(Eu/Eu^(*)=0.07-0.20).Zircon saturation thermometry yields high crystallization temperatures(TZr≈908.87℃)and low emplacement pressures(1.46 kbar)under reducing conditions(ƒO_(2)≈−11.5).The mineralogical and geochemical results reveal that HGAFG originated from a hybrid,fluorine-rich magma generated by anatexis of lower crust,followed by extensive fractional crystallization,during late post-collisional extension associated with lithospheric delamination.The reduced nature and fluorine enrichment of HGAFG magma promoted the mineralization of Nb-Ta-REE phases,highlighting its significance as a fertile,high-temperature product of the terminal magmatic stage in ANS evolution.
基金supported by the National Natural Science Foundation of China(41902310,42372348,42372286)Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(2024ZD1003607)+2 种基金China Geological Survey Projects(DD20230700802,DD20221819)the Basic Research Fund of the Chinese Academy of Geological Sciences(JKYQN202306)Key Research and Development Program of Shanxi Province,China(202102090301009).
文摘The Mianhuakeng uranium deposit,characterized by uranium-rich granite,serves as a key site for research into crustal radioactive heating.Based on 45 rock samples,this study reviews that the host granite in the Mianhuakeng uranium deposit has a high radioactive heat production rate(avg.5.50μW/m³)and a low Th/U ratio(avg.2.62).Uranium-rich granite and its alteration zone within the upper crust(0-5 km depth)contribute about 45%of the total radioactive heat production,wich is crucial for controlling geothermal resource distribution.For uranium-thermal at tectonic plate margins,a symbiotic geological model was proposed:Firstly,subduction of the Pacific Plate caused upwelling of the asthenosphere,generating a high heat-flow background.Secondly,heat transfer is enhanced by major faults such as the Youdong and Mianhuakeng faults.Subsequently,uranium was mobilized,transported,and enriched within the granite through deep siliceous hydrothermal activity and associated alteration.Ultimately,the uranium enrichment in granite leads to increased radioactive heat production,resulting in local thermal anomalies.This model provides a theoretical support for exploring and developing uranium-thermal symbiotic resources in South China.
基金supported by the National Key Research and Develpoment Program of China (No. 2017YFC0602701)the China Postdoctoral Science Foundation (No. 2017M610960)the China Geological Survey’s projects (Nos. DD20190173 and DD20190379)
文摘Strategic emerging minerals such as lithium,beryllium,niobium and tantalum are the most important rare metals currently,especially with the increasing demand of emerging industries on rare metals in China.The Jiajika deposit with a complete Li-Be-Nb-Ta metallogenic series is the largest pegmatite type rare metal deposit in China at present.In this paper,systematic researches of geochronology and petrogeochemistry were carried out to understand the genetic relationships between mineralization and magma evolution in the Jiajika deposit,which might be helpful to further rare-element prospecting in Songpan-Garze area.Zircon LA-ICP-MS U-Pb dating yields a concordia age of 217±1.1 Ma and a weighted mean 206 Pb/238 U age of 217±0.84 Ma for the aplite from the No.308 pegmatite.Cassiterite LA-MC-ICPMS dating yields concordant ages of 211±4.6 Ma for the No.308 pegmatite vein and198±4.4 Ma for the No.133 pegmatite vein,indicating that the rare metal mineralization mainly occurred in the Late Indosinian Period,further suggesting that the granites,aplites and pegmatites in Jiajika formed during a relatively stable stage after the intense orogeny of the Indosinian cycle.The rare metal-bearing granitic rocks and pegmatites show a clear linear relationship between A/CNK and A/NK and are enriched in total alkalis and depleted in CaO,FeO,MnO,MgO,Ba and Sr.All barren rocks and mineralized rocks feature similar rare earth element and trace element geochemical patterns.Thus,these characteristics indicate that the aplites and pegmatites represent the highly differentiated products of the two-mica granite(MaG)in this area,which is the most likely parent magma.During the evolution of magma,strong alkali metasomatism occurred between the melt phase and the volatile-rich fluid phase;as a result,large-scale rare metal mineralization occurred in certain structural zones of the pegmatite veins in the Jiajika deposit.
文摘The granitic gneisses from the ultrahigh-pressure (UHP) metamorphic terrain of the southeastern Dabie Mountains encompass two types: monzonitic granitic gneiss and alkali-feldspar granitic gneiss, which are characterized by rich alkalis, poor CaO, high FeO/MgO, particularly high Ba, Rb, Th, Ta, REE (except Eu), Ga, Nb and Zn, and low Sr, Eu, Cr, Co and Ni. The gneisses, particularly the alkali-feldspar granitic gneiss, have typical chemical characteristics of A-type granites. They resulted from partial melting of crustal materials existing in the rift zone along the northern margin of the South China block during the Neoproterozoic. These gneisses might not have undergone UHP metamorphism during the late Triassic, but were involved into UHP rocks by the tectonic mixing process and kept the exhumation message of the UHP rocks from the middle and upper crust.
基金Financial support assistance from Global-Centre of Excellent (GCOE) program Kyushu University
文摘We report for the first time the geochemistry of rare earth elements（REE） in the weathered crusts of I-type and calc-alkaline to high-K（shoshonitic） granitic rocks at Mamasa and Palu region, Sulawesi Island, Indonesia. The weathered crusts can be divided into horizon A（lateritic profile） and B（weathered horizon）. Quartz, albite, kaolinite, halloysite and montmorrilonite prevail in the weathered crust. Both weathered profiles show that the total REE increased from the parent rocks to the horizon B but significantly decrease toward the upper part（horizon A）. LREE are enriched toward the upper part of the profile as shown by La/YbN value. However, HREE concentrations are high in horizon B1 in Palu profile. The total REE content of the weathered crust are relatively elevated compared to the parent rocks, particularly in the lower part of horizon B in Mamasa profile and in horizon B2 in Palu profile. This suggests that REE-bearing accessory minerals may be resistant against weathering and may remain as residual phase in the weathered crusts. The normalized isocon diagram shows that the mass balance of major and REE components between each horizon in Mamasa and Palu weathering profile are different. The positive Ce anomaly in the horizon A of Mamasa profile indicated that Ce is rapidly precipitated during weathering and retain at the upper soil horizon.
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This study was financially supported by the National Natural Science Foundation of China(grants 40421303 and 40234046).
文摘The LA-ICPMS zircon U-Pb geochronology of three typically Indosinian granitic plutons yielded weighted mean ^206pb/^238U ages of 214.1±5.9 Ma and 210.3±4.7 Ma for the biotite monzonitic granites from the Xiema and Xiangzikou plutons in Hunan Province, and 205.3±1.6 Ma for biotite granite from the Napeng pluton, western Guandong Province, respectively, showing a similar late Indosinian age of crystallization. In combination with other geochronological data from Indosinian granites within the South China Block （SCB）, it is proposed that those late Indosinian granites with an age of -210 Ma and the early Indosinian granites （230-245 Ma） have the similar petrogenesis in identical tectonic setting. The Indosinian granites within the SCB might be the products of anatexis of the thickening crust in a compressive regime. These data provide a further understanding for the temporal and spatial distribution of the Indosinian granites and the dynamic evolution of the SCB.
