The main objective of the present work is to investigate the properties of plasmas created by injecting a thermalized beam of antiprotons in two types of media. The first is hydrogen, deuterium, or tritium atoms local...The main objective of the present work is to investigate the properties of plasmas created by injecting a thermalized beam of antiprotons in two types of media. The first is hydrogen, deuterium, or tritium atoms localized in palladium crystals. The second medium is composed of protons, deuterons, or tritons localized in a magnetic cavity. Particularly, it is demonstrated that huge amounts of energy are released in both cases which could be used as fuels for space shuttle engines. A novel mathematical scheme is employed to calculate the energy yields in real space at different incident energies of the antiprotons.展开更多
We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-...We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-2(SHANS2),a gas-filled recoil separator located at the China Accelerator Facility for Superheavy Elements(CAFE2).In total,20 decay chains are attributed to ^(288)Mc and 1 decay chain is assigned to ^(287)Mc.The measured oa-decay properties of ^(287,288)Mc as well as its descendants are consistent with the known data.No additional decay chains originating from the 2n or 5n reaction channels were detected.The excitation function of the ^(243)Am(^(48)Ca,3n)^(288)Mc reaction was measured at the cross-section level of picobarn,which indicates the promising capability for the study of heavy and superheavy nuclei at the facility.展开更多
The Arno River Basin(Central Italy)is affected by a considerable anthropogenic pressure due to the presence of large cities and widespread industrial and agricultural practices.In this work,26 water samples from the A...The Arno River Basin(Central Italy)is affected by a considerable anthropogenic pressure due to the presence of large cities and widespread industrial and agricultural practices.In this work,26 water samples from the Arno River and its main tributaries were analyzed to assess the water pollution status.The geochemical composition of the Arno River changes from the source(dominated by a Ca-HCO_(3) facies)to the mouth(where a Na-Cl(SO4)chemistry prevails)with an increasing quality deterioration,as suggested by the Chemical Water Quality Index,due to anthropogenic contributions and seawater intrusion before flowing into the Ligurian Sea.The Ombrone and Usciana tributaries introduce anthropogenic pollutants into the Arno River,whilst Elsa tributary supplies significant contents of geogenic sulfate.The concentrations of dissolved nitrate and nitrite(up to 63 and 9 mg/L,respectively)and the respective isotopic values of𝛿15N and𝛿18O were also determined to understand origin and fate of the N-species in the Arno River Basin surface waters.The combined application of𝛿15N-NO_(3) and𝛿18O-NO_(3) and N-source apportionment modelling allowed the identification of soil organic nitrogen and sewage and domestic wastes as primary sources for dissolved NO_(3)-.The𝛿15N-NO_(2) and𝛿18O-NO_(2) values suggest that the nitrification process affects the ARB waters,thus controlling the abundances and proportion of the N-species.Our work indicates that additional efforts are needed to improve management strategies to reduce the release of nitrogenated species to the surface waters of the Arno River Basin,since little progress has been made from the early 2000s.展开更多
CM chondrites contain valuable insights into the formation and evolution of the solar nebula,as well as the secondary aqueous alteration processes that affected their parent bodies.Our study focuses on primary and sec...CM chondrites contain valuable insights into the formation and evolution of the solar nebula,as well as the secondary aqueous alteration processes that affected their parent bodies.Our study focuses on primary and secondary sulfides within the Aguas Zarcas(CM2)chondrite,investigating their formation mechanisms based on their morphology,textures,and compositions.Moreover,we infer the formation temperatures of the sulfides from 230 to 500℃ for primary and from 100 to 135℃ for secondary.We select representative grains and conduct Fe isotope measurements on them.The primary sulfides with δ^(56/54)Fe ranging from -2.44‰ to +0.69‰are associated with sulfidesilicate melt segregation,while secondary sulfides with δ^(56/54)Fe values between -1.83‰ and -0.14‰ are linked to aqueous alteration.Overall,the Ni content of the grains is positively correlated with δ^(56/54)Fe.It might be related to the changes in crystal structure and chemical bond lengths due to the increase in nickel content.Fe isotopes provide a new perspective on sulfide formation and the evolution of a carbonaceous chondrite parent body.展开更多
In recent years,terbium radioisotopes have been investigated for their potential therapeutic and diagnostic applications in nuclear medicine.This study aimed to investigate the production of ^(152) Tb and ^(155) Tb by...In recent years,terbium radioisotopes have been investigated for their potential therapeutic and diagnostic applications in nuclear medicine.This study aimed to investigate the production of ^(152) Tb and ^(155) Tb by alpha-induced reactions in detail,with a specific focus on determining the optimum production parameters and testing existing nuclear models.Given the limited number of experiments conducted on reactions related to terbium isotope production,it is necessary to perform theoretical calculations of cross sections over a wide energy range to gain a detailed understanding of terbium isotope production.To achieve this objective,the cross sections of the ^(151)Eu(α,n)^(154) Tb reactions were calculated up to 60 MeV using the TALYS computer code with 432 different combinations of optical model parameters,level density,and strength function models.The theoretical reaction cross-section results were compared with the experimental results in the literature.The best input parameters were determined using the Threshold Logic Unit method,and these parameters were used in all isotope production calculations.Once the optimal model combination was determined,the total activity production and isotopic fraction of ^(152) Tb and ^(155) Tb isotopes were calculated in detail for beam energies of 17–50 MeV,different irradiation times,and varying ^(151) Eu and ^(153) Eu target thicknesses.展开更多
Medical isotopes are the foundation material for nuclear medicine and are primarily produced through in-reactor irradia-tion.Neutron spectrum regulation is the main technical approach for enhancing the production of m...Medical isotopes are the foundation material for nuclear medicine and are primarily produced through in-reactor irradia-tion.Neutron spectrum regulation is the main technical approach for enhancing the production of medical isotopes,and it requires determining the optimal neutron spectrum and quantifying the values of neutrons in different energy regions.We calculated the neutron energy region values for 20 medical isotopes(^(14)C,^(32)P,^(47)Sc,^(60)Co,^(64)Cu,^(67)Cu,^(89)Sr,^(90)Y,^(99)Mo,^(125)I,^(131)I,^(153)Sm,^(161)Tb,^(166)Ho,^(177)Lu,^(186)Re,^(188)Re,^(92)Ir,^(225)Ac,and ^(252)Cf).The entire energy range was divided into 238 energy regions to improve the energy spectrum resolution,and both fast and thermal reactors were simulated to enhance universal applicability.A dataset of neutron energy region values across the entire energy range was built,which identifies the positive and negative-energy regions and guides the neutron spectrum regulation process during in-reactor medical isotope produc-tion.We conducted neutron spectrum regulation based on this dataset,which effectively improved the production efficiency of medical isotopes and demonstrated the correctness and feasibility of the dataset.展开更多
Hydrocarbons are one of the important fluids within the Earth's crust,and different biotic and abitoic processes can generate hydrocarbon during geological periods.Tracing the sources and sinks of hydrocarbons can...Hydrocarbons are one of the important fluids within the Earth's crust,and different biotic and abitoic processes can generate hydrocarbon during geological periods.Tracing the sources and sinks of hydrocarbons can help us better understand the carbon cycle of the earth.In this study,an improved approach of adsorbed hydrocarbons extraction from sediments was established.The improved thermal desorption approach,compound-specific isotope analysis and position-specific isotope analysis were integrated to investigate the molecular and intramolecular isotope fractionation between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The isotopic compositions of the terminal position carbon of propane(δ^(13)C_(terminal))serves as a correlation indicator between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The tight sandstone gas from the Turpan-Hami Basin is a first case study for the application of this novel method to trace hydrocarbon origins.The results showed that the hydrocarbons in the tight sandstone gases in the study area most likely originated from humic organic matter(typeⅢkerogen)at an early mature stage.δ^(13)C_(terminal)values of the thermally desorbed propane gases from different source rocks were distinguishable and the values of the tight sandstone gases significantly overlap with those of the Lower Jurassic Sangonghe source rocks,suggesting their genetic relationship.Overall,the results provided novel position-specific carbon isotopic constraints on origins of hydrocarbons.展开更多
Precipitation isotopes(δ^(18)O and δ^(2)H)are closely related to meteorological conditions for precipitation generation and the initial state of water vapor source areas,and are essential to the study of the regiona...Precipitation isotopes(δ^(18)O and δ^(2)H)are closely related to meteorological conditions for precipitation generation and the initial state of water vapor source areas,and are essential to the study of the regional hydrological cycle.The deuterium excess(d-excess)indicates deviation in isotope fractionation during evaporation and can trace water vapor sources.This study analyzed 443 precipitation samples collected from the Gannan Plateau,China in 2022 to assess precipitation isotope variations and their driving factors.Water vapor sources were evaluated using the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT),Concentration Weighted Trajectory(CWT),and Potential Source Contribution Factor(PSCF)models.Results showed that precipitation isotope values showed significant spatial and temporal variations on the Gannan Plateau.Temporally,precipitation isotope values peaked in June(when evaporation dominated)and minimized in March(depletion effect of air masses in the westerly wind belt).Spatially,the isotope values showed a distribution pattern of"high in the east and low in the west",which was mainly regulated by the differences in altitude and local meteorological conditions.Compared with the global meteoric water line(GMWL)with equation of δ^(2)H=8.00δ^(18)O+10.00,the slope and intercept of local meteoric water line(LMWL)for precipitation on the Gannan Plateau were smaller(7.49 and 7.63,respectively),reflecting the existence of a stronger secondary evaporation effect under the clouds in the region.The sources of water vapor on the Gannan Plateau showed significant seasonality and spatial heterogeneity.Specifically,the westerly belt and monsoon were the main water vapor transport paths at each sampling point,with Central Asian continental water vapor dominating in spring(53.49%),Indian Ocean water vapor dominating in summer(52.53%),Atlantic Ocean water vapor dominating in autumn(46.74%),and Atlantic Ocean and Mediterranean Sea water vapor dominating in winter(42.30%and 33.68%,respectively).Changes in the intensity of convective activity and Outgoing Longwave Radiation(OLR)affected the enrichment of isotopic values,which exhibited the same change trends as δ^(18)O.During the precipitation process,the δ^(18)O value first decreased and then increased.During the initial and final stages of precipitation process,precipitation was mainly influenced by continental air masses,while during the middle stage,it was controlled by marine air masses.The systematic research on precipitation isotopes and water vapor sources is important for climate change research and extreme precipitation prediction on the Gannan Plateau and other similar areas.展开更多
Coal power plants annually generate quantities of byproducts that release environmentally hazardous heavy metals like Cd and Pb.Understanding the behavior and spatiotemporal impacts on soils of these releases is cruci...Coal power plants annually generate quantities of byproducts that release environmentally hazardous heavy metals like Cd and Pb.Understanding the behavior and spatiotemporal impacts on soils of these releases is crucial for pollution control.This study investigated the concentrations and isotope ratios of Cd/Pb in combustion byproducts,depositions and soils collected froma coal-fired power plant or its surrounding area.The pulverized fuel ash(PFA)and desulfurized gypsum(DG)exhibited heavier Cd isotopes withΔ^(114)Cd values of 0.304‰and 0.269‰,respectively,while bottom ash(BA)showed lighter Cd isotopes(Δ^(114)CdBA-coal=–0.078‰),compared to feed coal.We proposed a two-stage condensation process that governs the distribution of Cd/Pb,including accumulation on PFA and DG within electrostatic precipitators and desulfurization unit,as well as condensation onto fine particles upon release from the stack.Emissions from combustion and large-scale transport make a significant contribution to deposition,while the dispersion of Cd/Pb in deposition is primarily influenced by the prevailing wind patterns.However,the distribution of Cd/Pb in soils not only exhibit predominant wind control but is also potentially influenced by the resuspension of long-term storage byproducts.The power plant significantly contributes to soil in the NW–N–NE directions,even at a considerable distance(66%–79%),demonstrating its pervasive impact on remote regions along these orientations.Additionally,based on the vertical behavior in the profile,we have identified that Cd tends to migrate downward through leaching,while variations in Pb respond to the historical progression of dust removal.展开更多
It has long been recognized that garnet has the capacity to preserve the trace element and isotopic signature of distinct metamorphic growth zones because of its high closure temperature.Combined with the large size o...It has long been recognized that garnet has the capacity to preserve the trace element and isotopic signature of distinct metamorphic growth zones because of its high closure temperature.Combined with the large size of certain garnet porphyroblast,this allows investigating variations in metamorphic conditions such as pressure,temperature,deviatoric stress,and fluid composition,which occur during subduction-related metamorphism.Here,one garnet porphyroblast of 6 cm diameter was sampled from the Yardoi schists of Xizang,and the major-,trace-,and Li-Mg isotopic compositions of distinct growth zones were determined in situ.The δ^(7)Li values range from+6.0‰to+4.1‰and follow‘S-shaped’patterns on both sides of the garnet’s core,revealing a two-stage growth process corresponding to the fluid-assisted sequential recrystallization of chlorite and micas during prograde metamorphism.By contrast,once corrected for the overprinting by retrograde metamorphism,theδ^(26)Mg values vary monotonically from−1.73‰in the core to−1.32‰in the outer rim,reflecting a single-step process interpreted to result from increasing temperature and the solid-state recrystallization of chlorite-biotite during prograde metamorphism.This different behavior of Li and Mg isotopes is interpreted to result from the fact that Li is more fluid-mobile than the major element Mg.展开更多
The Cretaceous Koum Basin is a rift-related half-graben in northern Cameroon,which constitutes a portion of the Yola Arm of the Upper Benue Trough.This study presents the first comprehensive dataset combining mineral-...The Cretaceous Koum Basin is a rift-related half-graben in northern Cameroon,which constitutes a portion of the Yola Arm of the Upper Benue Trough.This study presents the first comprehensive dataset combining mineral-ogical,bulk-rock geochemical,and stable C-H-O isotopic data for dark-gray,finegrained mudstones from the basin,providing new insights into its sediment source,paleoenvironment,and geodynamic setting.The mudstones primarily consist of phyllosilicates(~8.6%),feldspars(~30.5%),carbonates(~13.7%),and minor iron oxides(~2.7%),with vermiculite,illite,and kaolinite as the main clay minerals.The presence of analcime,ankerite,and dolomite suggests low-grade metamorphism and/or hydrothermal alteration.Fe_(2)O_(3)/K_(2)O(1.52-6.40)and SiO_(2)/Al_(2)O_(3)(2.97-4.68)ratios classify the mudstones as compositionally immature shales(ICV~1.64)with low-moderate chemical weathering(CIA~56.35;PIA~59.74;R^(3+)/R^(3+)+R^(2+)+M^(+)~0.51).Trace element ratios(Th/Sc~1.70,Zr/Sc~1.33,La/Sc~6.30,La/Th~4.14)indicate an intermediate igneous provenance from a continental crustal source.Paleoenviron-mental proxies suggest deposition in a dynamic basin environment marked by fluctuating redox(C org/P:0.21-178.34)and salinity(Sr/Ba:0.34-3.25;N-values:48-35.92)conditions,ranging from oxic to anoxic and brackish to saline.Major element data(SiO_(2) vs.Al_(2)O_(3)+K_(2)O+Na_(2)O)indicate a semi-arid regime,while Paleoclimatic indicators such as Sr/Cu(1.88-37.47)and C-values(0.12-0.93)suggests alter-nating humid and arid conditions.Notably,stable isotope data,reported here for the first time in the Koum Basin,reveal a predominantly terrestrial,fluvial-deltaic C_(3) plant source for organic carbon(δ^(13)C-25.2‰ to -35.2‰)and complex fluid-rock interactions involving meteoric and magmatic-metamorphic fluids under a warm,equatorial climate(δ^(18)O+3.6‰to +24.9‰,δ^(2)H-104‰ to-50‰).The combined mineralogical,geochemical,and isotopic data point to deposition in a tectonically active continental arc setting,with contributions from ocean island arc and passive margin sources.展开更多
The pervasively distributed granitoids in South China contributed greatly to regional polymetallic mineralization,including tungsten,tin,copper,gold,rare metals,and rare earth elements(REEs).To ascertain the dynamic b...The pervasively distributed granitoids in South China contributed greatly to regional polymetallic mineralization,including tungsten,tin,copper,gold,rare metals,and rare earth elements(REEs).To ascertain the dynamic backgrounds,rock types and genesis of the parent rocks related to the Early-Middle Jurassic ionic rare earth mineralization,typical deposits at Muzishan,Xiahu,and Zudong were investigated by conducting petrographic,geochronologic,whole-rock geochemical,and Sr-Nd-Pb isotope analyses,which found that the parent rocks from the Muzishan deposit were the A1-type K-feldspar granite(~195 Ma),from the Zudong deposit were the A2-type monzogranite(~171 Ma),and from the Xiahu deposit were the I-type monzogranite(~167 Ma).All the three granitic rocks underwent different degrees of fractionation,with the Xiahu granite experiencing the highest degree,followed by the Zudong granite,and the Muzishan granite undergoing the lowest degree.The Muzishan granite was concluded to be formed under an intraplate extensional tectonic regime influenced by the hotspots or the mantle plume.The Zudong granite was formed in a post-arc extensional setting related to subduction-collision-rollback of the paleo-Pacific Plate,which caused upwelling of the asthenosphere,thinning of the lithosphere,and partial melting of crustal materials.The Xiahu granite was generated under a transitional tectonic setting of extension and compression,triggered by delamination and rollback of the paleo-Pacific Plate.展开更多
In many places across the globe,including the Wassa District of Ghana,groundwater provides a significant supply of water for various purposes.Understanding the groundwater origin and hydrogeochemical processes control...In many places across the globe,including the Wassa District of Ghana,groundwater provides a significant supply of water for various purposes.Understanding the groundwater origin and hydrogeochemical processes controlling the groundwater chemistry is a major step in the sustainable management of the aquifers.A total of 29groundwater samples were collected and analysed.Ionic ratio graphs,multivariate statistical analysis,mineral saturation indices,stable isotopes,and geostatistics methods were used to examine the sources and the quality of the groundwater.The findings describe the water types in the district as Ca-Mg-HCO_(3)-Cl,Ca-Na-HCO_(3),Na-Ca-HCO_(3),Ca-Na-HCO_(3)-Cl,Na-Ca-HCO_(3)-Cl,mix water type,NaHCO_(3)-Cl,with possible evolution to Ca-Na-Cl-HCO_(3),and Na-Ca-Cl-HCO_(3).According to the IEWQI for drinking water,around 53.6% of the samples have good quality,whereas 10.7% have very low-quality groundwater.Only 3.45% of the samples are suitable to use for irrigation without treatment,whereas 41.4% are somewhat safe with minimal treatment.Water-rock interactions,including the dissolution and weathering of silicate minerals,cation exchange processes,and human activities like mining andquarrying,are some of the main factors influencing groundwater chemistry.Principal component analysis revealed that groundwater chemistry is influenced by a combination of natural and anthropogenic sources.The APCs-MLR receptor model quantifies the factors that play important roles in groundwater salinization,including mineral dissolution and weathering(19.4%),localised Cd(16%),Ni(14.6%),Pb(12.8%),and Fe(11.4%)contamination from urbanisation while unidentified sources of pollution account for about 26.0%.The stable isotopes revealed groundwater is of meteoric origin and water-rock interaction the major mechanism for groundwater mineralization.The results of this research highlight the need of implementing an integrated strategy for managing and accessing groundwater quality.展开更多
Permian—Triassic granitoids are widely distributed along the Jinshajiang suture belt,eastern Xizang,and are regarded as the result of the tectonic-magmatic activity associated with the evolution of Paleo-Tethys Ocean...Permian—Triassic granitoids are widely distributed along the Jinshajiang suture belt,eastern Xizang,and are regarded as the result of the tectonic-magmatic activity associated with the evolution of Paleo-Tethys Ocean.This paper focuses on the high-K calc-alkaline I-type Rennong(~235 Ma)and Jiaduoling(~232 Ma)granitoid plutons,eastern Xizang,which are enriched in light rare earth elements(LREEs)and large ion lithophile elements(LILEs),but depleted in high field strength elements(HFSEs)with moderate-weak negative Eu anomalies(0.61–0.90).The Rennong granites are characterized by uniform zircon ε_(Hf)(t)values(-7.3 to-3.5)and negative ε_(Nd)(t)values(-7.6 to-5.7),with old two-stage Nd model ages(T_(DM2)=1.51-1.46 Ga)and was likely formed by partial melting of the basement rocks,whereas the Jiaduoling rock samples have variable zircon ε_(Hf)(t)values(-5.7 to+5.5)but negativeεNd(t)values(-7.6 to-7.7)and are proposed to be formed by hybridization of mantle-derived mafic magma,Rennong felsic magma and sediments.Mafic microgranular enclaves(MMEs)in the Jiaduoling granitic rocks,have similar zircon U-Pb ages(~237 Ma)and zircon ε_(Hf)(t)values(-4.4 to+6.3)to the host rocks,indicating that zircons in the MMEs were actually xenocrysts that formed at an early stage in the granitic magma chamber.These results reveal that the break-off of the Jinshajiang oceanic slab beneath Changdu(Qamdo)-Simao Block was in a post-collisional setting,resulted in the upwelling of asthenosphere in the Late Triassic,and then,generated the wide-spread intermediate-felsic magmatism along the Jinshajing belt,including the Rennong and Jiaduoling plutons.展开更多
Identifying the sources and characteristics of water pollution is essential for the protection and management of water environments.Nitrate(NO_(3)^(-))is a key pollutant affecting water quality in the Qingshui River,a...Identifying the sources and characteristics of water pollution is essential for the protection and management of water environments.Nitrate(NO_(3)^(-))is a key pollutant affecting water quality in the Qingshui River,a typical semi-arid tributary in the upper Yellow River basin.This study aimed to investigate the spatiotemporal patterns and sources of NO_(3)^(-)in the basin using an integrated analysis of hydrochemistry,stable isotopes,and dissolved organic matter(DOM)fluorescence.Hydrochemical results revealed that the water quality exhibited distinct seasonal variations,influenced by the unique hydrological and climatic conditions of the upper Yellow River.The surface water showed elevated concentrations of NO_(3)^(-)with limited denitrification,and NO_(3)^(-)accumulation was driven by multiple sources.Based on the dual isotopes(δ^(15)N andδ^(18)O)and the MixSIAR model,it was quantitatively determined that allochthonous inputs—including chemical nitrogen fertilizer,soil nitrogen,domestic sewage,and manure—constituted the primary sources of NO_(3)^(-).DOM fluorescence analysis revealed active biological or microbial metabolic activities,while allochthonous DOM significantly contributed to NO_(3)^(-)contamination.Both the MixSIAR model and DOM fluorescence results confirmed that protein-like substances were mainly derived from domestic sewage,whereas humic-like substances originated from non-point source pollution in the study area.These findings demonstrate the feasibility of combining isotopic and DOM fluorescence approaches to trace NO_(3)^(-)sources in surface water.This integrated methodology can support the design of targeted zonal management strategies to protect the surface water environment and maintain sustainable socioeconomic systems in semi-arid regions.展开更多
The separation of lithium isotopes (^(6)Li and ^(7)Li) is of great importance for the nuclear industry.The lithium amalgam method is the only lithium isotopes separation process in industry,and the extensive use of me...The separation of lithium isotopes (^(6)Li and ^(7)Li) is of great importance for the nuclear industry.The lithium amalgam method is the only lithium isotopes separation process in industry,and the extensive use of mercury has raised concerns about its potential environmental hazards,which have prompted the search for more efficient and environmentally friendly alternatives.Crown ethers can bind lithium ions highly selectively and separate lithium isotopes effectively.A chemical exchange-based lithium isotopes separation method using crown ether decorated materials could be a viable and cost-effective alternative to the lithium amalgam method.In this review,we provide a systematic summary of the recent advances in lithium isotopes separation using crown ethers decorated materials.展开更多
The origin of dolostone in the Middle Jurassic Buqu Formation of the Plateau Basin has been a subject of prolonged debate.This study combines detailed petrological observations with analyses of Mg-C-O isotopes and ele...The origin of dolostone in the Middle Jurassic Buqu Formation of the Plateau Basin has been a subject of prolonged debate.This study combines detailed petrological observations with analyses of Mg-C-O isotopes and elements to constrain the origin of dolostones in the Buqu Formation.Petrography and cathodoluminescence(CL)examination identified three types of matrix dolostones:very finely to finely crystalline dolostone(D1),finely to medium crystalline dolostone(D2),and medium to coarsely crystalline dolostone(D3).The analysis of the diagenesis sequence reveals that D1 originated from the dolomitization of grainstone in the early diagenetic phase,whereas D2 and D3 resulted from the recrystallization of D1 during the later burial phase.The presence of high Na(>100 ppm),low Fe(<1000 ppm),low Mn(<250 ppm),positive Ce anomaly,LREE enrichment,stableδ^(26)Mg(-2.28‰to-2.04‰),andδ^(13)C(1.02‰-2.95‰)indicates that the early dolomitization fluid was oxidized seawater.As the crystal size increases(D1→D2→D3),the progressively rising Mn content and significantly negativeδ^(18)O(-10.72‰to-7.81‰)suggest that the dolostone has experienced modification and alteration by buried pore water in the later stages.The fluctuations in relative sea level during the sedimentary deposition of the Buqu Formation were reconstructed through the utilization of Na,Sr/Cu,Sr/Ba,Rb/Sr,∑REE,andδ^(13)C.It was observed that theδ^(26)Mg of dolostone closely mirrored the variations in sea level.The consistent trend of change confirms that sea level fluctuations control the formation and distribution of early dolostone.Frequent sea level rise and fall prompted the limestone deposited on the carbonate platform to be continuously transformed into dolostone,which accumulates over a long period to form large-scale thick dolostone.After the formation entered the burial stage,under the combined action of high Mg/Ca ratio pore water,high temperature,and high pressure,the early dolostone experienced the adjustment of burial dolomitization.This research offers a typical case study on the application of Mg-C-O isotope and elements to determine the origin of dolostone.This will aid in a more comprehensive understanding of the formation process of dolostone in ancient rock records.展开更多
The Arabian-Nubian Shield(ANS)serves as a key geological archive,preserving the tectono-thermal evolution associated with the Rodinia breakup(∼900–800 Ma)and Gondwana formation(∼800–620 Ma).The Katherina Ring Comp...The Arabian-Nubian Shield(ANS)serves as a key geological archive,preserving the tectono-thermal evolution associated with the Rodinia breakup(∼900–800 Ma)and Gondwana formation(∼800–620 Ma).The Katherina Ring Complex(KRC),located in the Sinai Peninsula,Egypt(northern ANS),exemplifies continental growth through multistage magmatism and orogenesis,spanning the Tonian to Ediacaran periods(∼900–530 Ma).Despite its importance,debates persist regarding the nature,age,crustal characteristics,and magma source evolution of its constituent units.Situated in the northwestern part of the KRC,the Wadi Rofaiyed Cu deposit offers an exceptional natural laboratory for investigating continental crust formation during this interval,owing to its superb exposure and preservation.This study integrates detailed fieldwork,petrographic analyses,whole-rock geochemistry,Sr-Nd isotopes,and in situ zircon U-Pb-Lu-Hf isotopic data.It aims to(i)establish a robust chronological framework for the unmetamorphosed plutonic rocks of the KRC,(ii)advance the understanding of associated geodynamic processes,and(iii)elucidate the episodic magmatism events.The findings show that Wadi Rofaiyed juvenile crust developed in four main phases:(i)a subduction-accretionary phase(∼755 Ma)characterized by intense calc-alkaline magmatism,originating from the partial melting of mafic lower crust;(ii)a syn-collisional phase(∼630 Ma)occurred during the collision between the Saharan metacraton and the younger ANS crust,producing I-type granitoids formed through magma mixing and crustal anatexis;(iii)a post-collisional phase characterized by intermediate I-type(∼595 Ma)to felsic A-type alkaline magma(∼594 Ma),originated from the partial melting of the overthickened lower crust corresponding to lithospheric delamination;and(iv)an anorogenic phase(∼530 Ma)related to the final amalgamation of Greater Gondwana.Isotopic analyses across all four magmatic phases reveal low initial^(87)Sr/^(86)Sr(0.702648–0.703311)and positiveε_(Hf)(t)(+2.84 to+7.78)andε_(Nd)(t)(+2.61 to+5.21)values,consistent with lower crustal sources with depleted mantle-like signatures.The model ages(T_(DM2))for these magmatic rocks derived from zircon Hf(1.2–1.5 Ga)and whole-rock Nd isotopes(0.96–1.17 Ga)support a predominantly juvenile crustal origin.These findings underscore the multistage tectono-magmatic evolution of the northern ANS,advancing our understanding of obduction-accretion dynamics and crustal development during the Neoproterozoic.展开更多
Within the framework of the isospin-dependent quantum molecular dynamics model,the fusion cross section and fusion mechanism of neutron-deficient Pu isotopes in the reactions24,26,30Si+196Hg were investigated.We found...Within the framework of the isospin-dependent quantum molecular dynamics model,the fusion cross section and fusion mechanism of neutron-deficient Pu isotopes in the reactions24,26,30Si+196Hg were investigated.We found that the fusion cross sections are higher in the reaction with a more neutron-rich beam owing to the lower dynamical barrier.The dynamical barrier decreases with decreasing incident energy,which explains the fusion enhancement at the sub-barrier energy.The peak value of N/Z ratio in the neck region is the highest in reaction30Si+196Hg,indirectly leading to the lowest dynamical barrier.Compared with the proton density distribution,the neck region for neutrons is larger,indicating that neutrons transfer more quickly than protons,leading to a high N/Z ratio in the neck.The time distribution of the appearance of dynamical barriers is wider at lower incident energies,indicating that the fusion process took longer to exchange nucleons.The single-particle potential barrier decreases with time evolution and finally disappears at a lower impact parameter,which is favorable for fusion events.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
文摘The main objective of the present work is to investigate the properties of plasmas created by injecting a thermalized beam of antiprotons in two types of media. The first is hydrogen, deuterium, or tritium atoms localized in palladium crystals. The second medium is composed of protons, deuterons, or tritons localized in a magnetic cavity. Particularly, it is demonstrated that huge amounts of energy are released in both cases which could be used as fuels for space shuttle engines. A novel mathematical scheme is employed to calculate the energy yields in real space at different incident energies of the antiprotons.
基金supported in part by the National Key R&D Program of China (Contract Nos.2023YFA1606500,2024YFE0109800,and 2024YFE0110400)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB34010000)+5 种基金the Gansu Key Project of Science and Technology (Grant No.23ZDGA014)the Guangdong Major Project of Basic and Applied Basic Research (Grant No.2021B0301030006)the National Natural Science Foundation of China (Grant Nos.12105328,W2412040,12475126,12422507,12035011,12375118,12435008,and W2412043)the Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.YSBR-002)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant Nos.2020409 and 2023439)the Russian Science Foundation (Grant No.25-42-00003)。
文摘We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-2(SHANS2),a gas-filled recoil separator located at the China Accelerator Facility for Superheavy Elements(CAFE2).In total,20 decay chains are attributed to ^(288)Mc and 1 decay chain is assigned to ^(287)Mc.The measured oa-decay properties of ^(287,288)Mc as well as its descendants are consistent with the known data.No additional decay chains originating from the 2n or 5n reaction channels were detected.The excitation function of the ^(243)Am(^(48)Ca,3n)^(288)Mc reaction was measured at the cross-section level of picobarn,which indicates the promising capability for the study of heavy and superheavy nuclei at the facility.
文摘The Arno River Basin(Central Italy)is affected by a considerable anthropogenic pressure due to the presence of large cities and widespread industrial and agricultural practices.In this work,26 water samples from the Arno River and its main tributaries were analyzed to assess the water pollution status.The geochemical composition of the Arno River changes from the source(dominated by a Ca-HCO_(3) facies)to the mouth(where a Na-Cl(SO4)chemistry prevails)with an increasing quality deterioration,as suggested by the Chemical Water Quality Index,due to anthropogenic contributions and seawater intrusion before flowing into the Ligurian Sea.The Ombrone and Usciana tributaries introduce anthropogenic pollutants into the Arno River,whilst Elsa tributary supplies significant contents of geogenic sulfate.The concentrations of dissolved nitrate and nitrite(up to 63 and 9 mg/L,respectively)and the respective isotopic values of𝛿15N and𝛿18O were also determined to understand origin and fate of the N-species in the Arno River Basin surface waters.The combined application of𝛿15N-NO_(3) and𝛿18O-NO_(3) and N-source apportionment modelling allowed the identification of soil organic nitrogen and sewage and domestic wastes as primary sources for dissolved NO_(3)-.The𝛿15N-NO_(2) and𝛿18O-NO_(2) values suggest that the nitrification process affects the ARB waters,thus controlling the abundances and proportion of the N-species.Our work indicates that additional efforts are needed to improve management strategies to reduce the release of nitrogenated species to the surface waters of the Arno River Basin,since little progress has been made from the early 2000s.
基金supported by the National Science Foundation of China(Nos.42225202 and 41827802)。
文摘CM chondrites contain valuable insights into the formation and evolution of the solar nebula,as well as the secondary aqueous alteration processes that affected their parent bodies.Our study focuses on primary and secondary sulfides within the Aguas Zarcas(CM2)chondrite,investigating their formation mechanisms based on their morphology,textures,and compositions.Moreover,we infer the formation temperatures of the sulfides from 230 to 500℃ for primary and from 100 to 135℃ for secondary.We select representative grains and conduct Fe isotope measurements on them.The primary sulfides with δ^(56/54)Fe ranging from -2.44‰ to +0.69‰are associated with sulfidesilicate melt segregation,while secondary sulfides with δ^(56/54)Fe values between -1.83‰ and -0.14‰ are linked to aqueous alteration.Overall,the Ni content of the grains is positively correlated with δ^(56/54)Fe.It might be related to the changes in crystal structure and chemical bond lengths due to the increase in nickel content.Fe isotopes provide a new perspective on sulfide formation and the evolution of a carbonaceous chondrite parent body.
文摘In recent years,terbium radioisotopes have been investigated for their potential therapeutic and diagnostic applications in nuclear medicine.This study aimed to investigate the production of ^(152) Tb and ^(155) Tb by alpha-induced reactions in detail,with a specific focus on determining the optimum production parameters and testing existing nuclear models.Given the limited number of experiments conducted on reactions related to terbium isotope production,it is necessary to perform theoretical calculations of cross sections over a wide energy range to gain a detailed understanding of terbium isotope production.To achieve this objective,the cross sections of the ^(151)Eu(α,n)^(154) Tb reactions were calculated up to 60 MeV using the TALYS computer code with 432 different combinations of optical model parameters,level density,and strength function models.The theoretical reaction cross-section results were compared with the experimental results in the literature.The best input parameters were determined using the Threshold Logic Unit method,and these parameters were used in all isotope production calculations.Once the optimal model combination was determined,the total activity production and isotopic fraction of ^(152) Tb and ^(155) Tb isotopes were calculated in detail for beam energies of 17–50 MeV,different irradiation times,and varying ^(151) Eu and ^(153) Eu target thicknesses.
基金sponsored by the National Natural Science Foundation of China(No.12305190)Lingchuang Research Project of China National Nuclear Corporation(CNNC).
文摘Medical isotopes are the foundation material for nuclear medicine and are primarily produced through in-reactor irradia-tion.Neutron spectrum regulation is the main technical approach for enhancing the production of medical isotopes,and it requires determining the optimal neutron spectrum and quantifying the values of neutrons in different energy regions.We calculated the neutron energy region values for 20 medical isotopes(^(14)C,^(32)P,^(47)Sc,^(60)Co,^(64)Cu,^(67)Cu,^(89)Sr,^(90)Y,^(99)Mo,^(125)I,^(131)I,^(153)Sm,^(161)Tb,^(166)Ho,^(177)Lu,^(186)Re,^(188)Re,^(92)Ir,^(225)Ac,and ^(252)Cf).The entire energy range was divided into 238 energy regions to improve the energy spectrum resolution,and both fast and thermal reactors were simulated to enhance universal applicability.A dataset of neutron energy region values across the entire energy range was built,which identifies the positive and negative-energy regions and guides the neutron spectrum regulation process during in-reactor medical isotope produc-tion.We conducted neutron spectrum regulation based on this dataset,which effectively improved the production efficiency of medical isotopes and demonstrated the correctness and feasibility of the dataset.
基金financially supported by the National Natural Science Foundation of China(Grant No.42102202)U.S.Department of Energy Geosciences program(DE-SC0016271)。
文摘Hydrocarbons are one of the important fluids within the Earth's crust,and different biotic and abitoic processes can generate hydrocarbon during geological periods.Tracing the sources and sinks of hydrocarbons can help us better understand the carbon cycle of the earth.In this study,an improved approach of adsorbed hydrocarbons extraction from sediments was established.The improved thermal desorption approach,compound-specific isotope analysis and position-specific isotope analysis were integrated to investigate the molecular and intramolecular isotope fractionation between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The isotopic compositions of the terminal position carbon of propane(δ^(13)C_(terminal))serves as a correlation indicator between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The tight sandstone gas from the Turpan-Hami Basin is a first case study for the application of this novel method to trace hydrocarbon origins.The results showed that the hydrocarbons in the tight sandstone gases in the study area most likely originated from humic organic matter(typeⅢkerogen)at an early mature stage.δ^(13)C_(terminal)values of the thermally desorbed propane gases from different source rocks were distinguishable and the values of the tight sandstone gases significantly overlap with those of the Lower Jurassic Sangonghe source rocks,suggesting their genetic relationship.Overall,the results provided novel position-specific carbon isotopic constraints on origins of hydrocarbons.
基金supported by the National Natural Science Foundation of China(42161007)the Innovation Foundation of Higher Education Institutions of Gansu Province(2021B-081)the Foundation for Distinguished Young Scholars of Gansu Province(20JR10RA112).
文摘Precipitation isotopes(δ^(18)O and δ^(2)H)are closely related to meteorological conditions for precipitation generation and the initial state of water vapor source areas,and are essential to the study of the regional hydrological cycle.The deuterium excess(d-excess)indicates deviation in isotope fractionation during evaporation and can trace water vapor sources.This study analyzed 443 precipitation samples collected from the Gannan Plateau,China in 2022 to assess precipitation isotope variations and their driving factors.Water vapor sources were evaluated using the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT),Concentration Weighted Trajectory(CWT),and Potential Source Contribution Factor(PSCF)models.Results showed that precipitation isotope values showed significant spatial and temporal variations on the Gannan Plateau.Temporally,precipitation isotope values peaked in June(when evaporation dominated)and minimized in March(depletion effect of air masses in the westerly wind belt).Spatially,the isotope values showed a distribution pattern of"high in the east and low in the west",which was mainly regulated by the differences in altitude and local meteorological conditions.Compared with the global meteoric water line(GMWL)with equation of δ^(2)H=8.00δ^(18)O+10.00,the slope and intercept of local meteoric water line(LMWL)for precipitation on the Gannan Plateau were smaller(7.49 and 7.63,respectively),reflecting the existence of a stronger secondary evaporation effect under the clouds in the region.The sources of water vapor on the Gannan Plateau showed significant seasonality and spatial heterogeneity.Specifically,the westerly belt and monsoon were the main water vapor transport paths at each sampling point,with Central Asian continental water vapor dominating in spring(53.49%),Indian Ocean water vapor dominating in summer(52.53%),Atlantic Ocean water vapor dominating in autumn(46.74%),and Atlantic Ocean and Mediterranean Sea water vapor dominating in winter(42.30%and 33.68%,respectively).Changes in the intensity of convective activity and Outgoing Longwave Radiation(OLR)affected the enrichment of isotopic values,which exhibited the same change trends as δ^(18)O.During the precipitation process,the δ^(18)O value first decreased and then increased.During the initial and final stages of precipitation process,precipitation was mainly influenced by continental air masses,while during the middle stage,it was controlled by marine air masses.The systematic research on precipitation isotopes and water vapor sources is important for climate change research and extreme precipitation prediction on the Gannan Plateau and other similar areas.
基金supported by the National Natural Science Foundation of China(No.42025705)the Construction Project of Modern Agricultural Science and Technology Innovation Alliance of Guangdong Province,China(No.2023KJ112)+1 种基金the National Natural Science Foundation of China(Nos.41977291 and 42177242)the GDAS’Project of Science and Technology Development,China(No.2019GDASYL-0103048).
文摘Coal power plants annually generate quantities of byproducts that release environmentally hazardous heavy metals like Cd and Pb.Understanding the behavior and spatiotemporal impacts on soils of these releases is crucial for pollution control.This study investigated the concentrations and isotope ratios of Cd/Pb in combustion byproducts,depositions and soils collected froma coal-fired power plant or its surrounding area.The pulverized fuel ash(PFA)and desulfurized gypsum(DG)exhibited heavier Cd isotopes withΔ^(114)Cd values of 0.304‰and 0.269‰,respectively,while bottom ash(BA)showed lighter Cd isotopes(Δ^(114)CdBA-coal=–0.078‰),compared to feed coal.We proposed a two-stage condensation process that governs the distribution of Cd/Pb,including accumulation on PFA and DG within electrostatic precipitators and desulfurization unit,as well as condensation onto fine particles upon release from the stack.Emissions from combustion and large-scale transport make a significant contribution to deposition,while the dispersion of Cd/Pb in deposition is primarily influenced by the prevailing wind patterns.However,the distribution of Cd/Pb in soils not only exhibit predominant wind control but is also potentially influenced by the resuspension of long-term storage byproducts.The power plant significantly contributes to soil in the NW–N–NE directions,even at a considerable distance(66%–79%),demonstrating its pervasive impact on remote regions along these orientations.Additionally,based on the vertical behavior in the profile,we have identified that Cd tends to migrate downward through leaching,while variations in Pb respond to the historical progression of dust removal.
基金supported by the National Natural Science Foundation of China(Nos.41729001,42073003,41673031).
文摘It has long been recognized that garnet has the capacity to preserve the trace element and isotopic signature of distinct metamorphic growth zones because of its high closure temperature.Combined with the large size of certain garnet porphyroblast,this allows investigating variations in metamorphic conditions such as pressure,temperature,deviatoric stress,and fluid composition,which occur during subduction-related metamorphism.Here,one garnet porphyroblast of 6 cm diameter was sampled from the Yardoi schists of Xizang,and the major-,trace-,and Li-Mg isotopic compositions of distinct growth zones were determined in situ.The δ^(7)Li values range from+6.0‰to+4.1‰and follow‘S-shaped’patterns on both sides of the garnet’s core,revealing a two-stage growth process corresponding to the fluid-assisted sequential recrystallization of chlorite and micas during prograde metamorphism.By contrast,once corrected for the overprinting by retrograde metamorphism,theδ^(26)Mg values vary monotonically from−1.73‰in the core to−1.32‰in the outer rim,reflecting a single-step process interpreted to result from increasing temperature and the solid-state recrystallization of chlorite-biotite during prograde metamorphism.This different behavior of Li and Mg isotopes is interpreted to result from the fact that Li is more fluid-mobile than the major element Mg.
文摘The Cretaceous Koum Basin is a rift-related half-graben in northern Cameroon,which constitutes a portion of the Yola Arm of the Upper Benue Trough.This study presents the first comprehensive dataset combining mineral-ogical,bulk-rock geochemical,and stable C-H-O isotopic data for dark-gray,finegrained mudstones from the basin,providing new insights into its sediment source,paleoenvironment,and geodynamic setting.The mudstones primarily consist of phyllosilicates(~8.6%),feldspars(~30.5%),carbonates(~13.7%),and minor iron oxides(~2.7%),with vermiculite,illite,and kaolinite as the main clay minerals.The presence of analcime,ankerite,and dolomite suggests low-grade metamorphism and/or hydrothermal alteration.Fe_(2)O_(3)/K_(2)O(1.52-6.40)and SiO_(2)/Al_(2)O_(3)(2.97-4.68)ratios classify the mudstones as compositionally immature shales(ICV~1.64)with low-moderate chemical weathering(CIA~56.35;PIA~59.74;R^(3+)/R^(3+)+R^(2+)+M^(+)~0.51).Trace element ratios(Th/Sc~1.70,Zr/Sc~1.33,La/Sc~6.30,La/Th~4.14)indicate an intermediate igneous provenance from a continental crustal source.Paleoenviron-mental proxies suggest deposition in a dynamic basin environment marked by fluctuating redox(C org/P:0.21-178.34)and salinity(Sr/Ba:0.34-3.25;N-values:48-35.92)conditions,ranging from oxic to anoxic and brackish to saline.Major element data(SiO_(2) vs.Al_(2)O_(3)+K_(2)O+Na_(2)O)indicate a semi-arid regime,while Paleoclimatic indicators such as Sr/Cu(1.88-37.47)and C-values(0.12-0.93)suggests alter-nating humid and arid conditions.Notably,stable isotope data,reported here for the first time in the Koum Basin,reveal a predominantly terrestrial,fluvial-deltaic C_(3) plant source for organic carbon(δ^(13)C-25.2‰ to -35.2‰)and complex fluid-rock interactions involving meteoric and magmatic-metamorphic fluids under a warm,equatorial climate(δ^(18)O+3.6‰to +24.9‰,δ^(2)H-104‰ to-50‰).The combined mineralogical,geochemical,and isotopic data point to deposition in a tectonically active continental arc setting,with contributions from ocean island arc and passive margin sources.
基金supported by the Open Fund Project of the Key Laboratory of Ionic Rare Earth Resources and Environment,Ministry of Natural Resources(Grant No.2022IREE101)the Young Elite Scientists Sponsorship Program by CAST(Grant No.2022QNRC001)the Geological Investigation Project(Grant Nos.DD20243483,DD20221643).
文摘The pervasively distributed granitoids in South China contributed greatly to regional polymetallic mineralization,including tungsten,tin,copper,gold,rare metals,and rare earth elements(REEs).To ascertain the dynamic backgrounds,rock types and genesis of the parent rocks related to the Early-Middle Jurassic ionic rare earth mineralization,typical deposits at Muzishan,Xiahu,and Zudong were investigated by conducting petrographic,geochronologic,whole-rock geochemical,and Sr-Nd-Pb isotope analyses,which found that the parent rocks from the Muzishan deposit were the A1-type K-feldspar granite(~195 Ma),from the Zudong deposit were the A2-type monzogranite(~171 Ma),and from the Xiahu deposit were the I-type monzogranite(~167 Ma).All the three granitic rocks underwent different degrees of fractionation,with the Xiahu granite experiencing the highest degree,followed by the Zudong granite,and the Muzishan granite undergoing the lowest degree.The Muzishan granite was concluded to be formed under an intraplate extensional tectonic regime influenced by the hotspots or the mantle plume.The Zudong granite was formed in a post-arc extensional setting related to subduction-collision-rollback of the paleo-Pacific Plate,which caused upwelling of the asthenosphere,thinning of the lithosphere,and partial melting of crustal materials.The Xiahu granite was generated under a transitional tectonic setting of extension and compression,triggered by delamination and rollback of the paleo-Pacific Plate.
文摘In many places across the globe,including the Wassa District of Ghana,groundwater provides a significant supply of water for various purposes.Understanding the groundwater origin and hydrogeochemical processes controlling the groundwater chemistry is a major step in the sustainable management of the aquifers.A total of 29groundwater samples were collected and analysed.Ionic ratio graphs,multivariate statistical analysis,mineral saturation indices,stable isotopes,and geostatistics methods were used to examine the sources and the quality of the groundwater.The findings describe the water types in the district as Ca-Mg-HCO_(3)-Cl,Ca-Na-HCO_(3),Na-Ca-HCO_(3),Ca-Na-HCO_(3)-Cl,Na-Ca-HCO_(3)-Cl,mix water type,NaHCO_(3)-Cl,with possible evolution to Ca-Na-Cl-HCO_(3),and Na-Ca-Cl-HCO_(3).According to the IEWQI for drinking water,around 53.6% of the samples have good quality,whereas 10.7% have very low-quality groundwater.Only 3.45% of the samples are suitable to use for irrigation without treatment,whereas 41.4% are somewhat safe with minimal treatment.Water-rock interactions,including the dissolution and weathering of silicate minerals,cation exchange processes,and human activities like mining andquarrying,are some of the main factors influencing groundwater chemistry.Principal component analysis revealed that groundwater chemistry is influenced by a combination of natural and anthropogenic sources.The APCs-MLR receptor model quantifies the factors that play important roles in groundwater salinization,including mineral dissolution and weathering(19.4%),localised Cd(16%),Ni(14.6%),Pb(12.8%),and Fe(11.4%)contamination from urbanisation while unidentified sources of pollution account for about 26.0%.The stable isotopes revealed groundwater is of meteoric origin and water-rock interaction the major mechanism for groundwater mineralization.The results of this research highlight the need of implementing an integrated strategy for managing and accessing groundwater quality.
基金supported by the National Natural Science Foundation of China(Nos.42072069,41403023)China Geological Survey(No.1212011121270)the Natural Science Foundation of Hainan Province(Nos.521QN274 and 421CXTD441).
文摘Permian—Triassic granitoids are widely distributed along the Jinshajiang suture belt,eastern Xizang,and are regarded as the result of the tectonic-magmatic activity associated with the evolution of Paleo-Tethys Ocean.This paper focuses on the high-K calc-alkaline I-type Rennong(~235 Ma)and Jiaduoling(~232 Ma)granitoid plutons,eastern Xizang,which are enriched in light rare earth elements(LREEs)and large ion lithophile elements(LILEs),but depleted in high field strength elements(HFSEs)with moderate-weak negative Eu anomalies(0.61–0.90).The Rennong granites are characterized by uniform zircon ε_(Hf)(t)values(-7.3 to-3.5)and negative ε_(Nd)(t)values(-7.6 to-5.7),with old two-stage Nd model ages(T_(DM2)=1.51-1.46 Ga)and was likely formed by partial melting of the basement rocks,whereas the Jiaduoling rock samples have variable zircon ε_(Hf)(t)values(-5.7 to+5.5)but negativeεNd(t)values(-7.6 to-7.7)and are proposed to be formed by hybridization of mantle-derived mafic magma,Rennong felsic magma and sediments.Mafic microgranular enclaves(MMEs)in the Jiaduoling granitic rocks,have similar zircon U-Pb ages(~237 Ma)and zircon ε_(Hf)(t)values(-4.4 to+6.3)to the host rocks,indicating that zircons in the MMEs were actually xenocrysts that formed at an early stage in the granitic magma chamber.These results reveal that the break-off of the Jinshajiang oceanic slab beneath Changdu(Qamdo)-Simao Block was in a post-collisional setting,resulted in the upwelling of asthenosphere in the Late Triassic,and then,generated the wide-spread intermediate-felsic magmatism along the Jinshajing belt,including the Rennong and Jiaduoling plutons.
基金The Basic Special Business Fund for Research and Development for the Central Level Scientific Research Institutes,Nanjing Institute of Environmental Sciences,MEE,Grant/Award Number:GYZX240103The Innovative Team Project of Nanjing Institute of Environmental Sciences,MEE,Grant/Award Number:GYZX200101Geological Prospecting Funds Program of Zhejiang Province,China,Grant/Award Number:No.2023021。
文摘Identifying the sources and characteristics of water pollution is essential for the protection and management of water environments.Nitrate(NO_(3)^(-))is a key pollutant affecting water quality in the Qingshui River,a typical semi-arid tributary in the upper Yellow River basin.This study aimed to investigate the spatiotemporal patterns and sources of NO_(3)^(-)in the basin using an integrated analysis of hydrochemistry,stable isotopes,and dissolved organic matter(DOM)fluorescence.Hydrochemical results revealed that the water quality exhibited distinct seasonal variations,influenced by the unique hydrological and climatic conditions of the upper Yellow River.The surface water showed elevated concentrations of NO_(3)^(-)with limited denitrification,and NO_(3)^(-)accumulation was driven by multiple sources.Based on the dual isotopes(δ^(15)N andδ^(18)O)and the MixSIAR model,it was quantitatively determined that allochthonous inputs—including chemical nitrogen fertilizer,soil nitrogen,domestic sewage,and manure—constituted the primary sources of NO_(3)^(-).DOM fluorescence analysis revealed active biological or microbial metabolic activities,while allochthonous DOM significantly contributed to NO_(3)^(-)contamination.Both the MixSIAR model and DOM fluorescence results confirmed that protein-like substances were mainly derived from domestic sewage,whereas humic-like substances originated from non-point source pollution in the study area.These findings demonstrate the feasibility of combining isotopic and DOM fluorescence approaches to trace NO_(3)^(-)sources in surface water.This integrated methodology can support the design of targeted zonal management strategies to protect the surface water environment and maintain sustainable socioeconomic systems in semi-arid regions.
基金support from the National Natural Science Foundation of China (Grant No.U21B2094 and Grant No.U2067212)。
文摘The separation of lithium isotopes (^(6)Li and ^(7)Li) is of great importance for the nuclear industry.The lithium amalgam method is the only lithium isotopes separation process in industry,and the extensive use of mercury has raised concerns about its potential environmental hazards,which have prompted the search for more efficient and environmentally friendly alternatives.Crown ethers can bind lithium ions highly selectively and separate lithium isotopes effectively.A chemical exchange-based lithium isotopes separation method using crown ether decorated materials could be a viable and cost-effective alternative to the lithium amalgam method.In this review,we provide a systematic summary of the recent advances in lithium isotopes separation using crown ethers decorated materials.
文摘The origin of dolostone in the Middle Jurassic Buqu Formation of the Plateau Basin has been a subject of prolonged debate.This study combines detailed petrological observations with analyses of Mg-C-O isotopes and elements to constrain the origin of dolostones in the Buqu Formation.Petrography and cathodoluminescence(CL)examination identified three types of matrix dolostones:very finely to finely crystalline dolostone(D1),finely to medium crystalline dolostone(D2),and medium to coarsely crystalline dolostone(D3).The analysis of the diagenesis sequence reveals that D1 originated from the dolomitization of grainstone in the early diagenetic phase,whereas D2 and D3 resulted from the recrystallization of D1 during the later burial phase.The presence of high Na(>100 ppm),low Fe(<1000 ppm),low Mn(<250 ppm),positive Ce anomaly,LREE enrichment,stableδ^(26)Mg(-2.28‰to-2.04‰),andδ^(13)C(1.02‰-2.95‰)indicates that the early dolomitization fluid was oxidized seawater.As the crystal size increases(D1→D2→D3),the progressively rising Mn content and significantly negativeδ^(18)O(-10.72‰to-7.81‰)suggest that the dolostone has experienced modification and alteration by buried pore water in the later stages.The fluctuations in relative sea level during the sedimentary deposition of the Buqu Formation were reconstructed through the utilization of Na,Sr/Cu,Sr/Ba,Rb/Sr,∑REE,andδ^(13)C.It was observed that theδ^(26)Mg of dolostone closely mirrored the variations in sea level.The consistent trend of change confirms that sea level fluctuations control the formation and distribution of early dolostone.Frequent sea level rise and fall prompted the limestone deposited on the carbonate platform to be continuously transformed into dolostone,which accumulates over a long period to form large-scale thick dolostone.After the formation entered the burial stage,under the combined action of high Mg/Ca ratio pore water,high temperature,and high pressure,the early dolostone experienced the adjustment of burial dolomitization.This research offers a typical case study on the application of Mg-C-O isotope and elements to determine the origin of dolostone.This will aid in a more comprehensive understanding of the formation process of dolostone in ancient rock records.
基金supported by the National Natural Science Foundation of China(No.92162103)the Natural Science Foundation of Hunan Province(No.2022JJ30699,No.2023JJ10064)the Science and Technology Innovation Program of Hunan Province(No.2021RC4055,No.2022RC1182).
文摘The Arabian-Nubian Shield(ANS)serves as a key geological archive,preserving the tectono-thermal evolution associated with the Rodinia breakup(∼900–800 Ma)and Gondwana formation(∼800–620 Ma).The Katherina Ring Complex(KRC),located in the Sinai Peninsula,Egypt(northern ANS),exemplifies continental growth through multistage magmatism and orogenesis,spanning the Tonian to Ediacaran periods(∼900–530 Ma).Despite its importance,debates persist regarding the nature,age,crustal characteristics,and magma source evolution of its constituent units.Situated in the northwestern part of the KRC,the Wadi Rofaiyed Cu deposit offers an exceptional natural laboratory for investigating continental crust formation during this interval,owing to its superb exposure and preservation.This study integrates detailed fieldwork,petrographic analyses,whole-rock geochemistry,Sr-Nd isotopes,and in situ zircon U-Pb-Lu-Hf isotopic data.It aims to(i)establish a robust chronological framework for the unmetamorphosed plutonic rocks of the KRC,(ii)advance the understanding of associated geodynamic processes,and(iii)elucidate the episodic magmatism events.The findings show that Wadi Rofaiyed juvenile crust developed in four main phases:(i)a subduction-accretionary phase(∼755 Ma)characterized by intense calc-alkaline magmatism,originating from the partial melting of mafic lower crust;(ii)a syn-collisional phase(∼630 Ma)occurred during the collision between the Saharan metacraton and the younger ANS crust,producing I-type granitoids formed through magma mixing and crustal anatexis;(iii)a post-collisional phase characterized by intermediate I-type(∼595 Ma)to felsic A-type alkaline magma(∼594 Ma),originated from the partial melting of the overthickened lower crust corresponding to lithospheric delamination;and(iv)an anorogenic phase(∼530 Ma)related to the final amalgamation of Greater Gondwana.Isotopic analyses across all four magmatic phases reveal low initial^(87)Sr/^(86)Sr(0.702648–0.703311)and positiveε_(Hf)(t)(+2.84 to+7.78)andε_(Nd)(t)(+2.61 to+5.21)values,consistent with lower crustal sources with depleted mantle-like signatures.The model ages(T_(DM2))for these magmatic rocks derived from zircon Hf(1.2–1.5 Ga)and whole-rock Nd isotopes(0.96–1.17 Ga)support a predominantly juvenile crustal origin.These findings underscore the multistage tectono-magmatic evolution of the northern ANS,advancing our understanding of obduction-accretion dynamics and crustal development during the Neoproterozoic.
基金supported by the National Natural Science Foundation of China(No.12405145)。
文摘Within the framework of the isospin-dependent quantum molecular dynamics model,the fusion cross section and fusion mechanism of neutron-deficient Pu isotopes in the reactions24,26,30Si+196Hg were investigated.We found that the fusion cross sections are higher in the reaction with a more neutron-rich beam owing to the lower dynamical barrier.The dynamical barrier decreases with decreasing incident energy,which explains the fusion enhancement at the sub-barrier energy.The peak value of N/Z ratio in the neck region is the highest in reaction30Si+196Hg,indirectly leading to the lowest dynamical barrier.Compared with the proton density distribution,the neck region for neutrons is larger,indicating that neutrons transfer more quickly than protons,leading to a high N/Z ratio in the neck.The time distribution of the appearance of dynamical barriers is wider at lower incident energies,indicating that the fusion process took longer to exchange nucleons.The single-particle potential barrier decreases with time evolution and finally disappears at a lower impact parameter,which is favorable for fusion events.
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.
