The composition and compound-specific isotopes of fatty acids were studied within food webs in the East China Sea.Lipid-normalized stable carbon isotopes of total organic carbon had a good correlation with trophic lev...The composition and compound-specific isotopes of fatty acids were studied within food webs in the East China Sea.Lipid-normalized stable carbon isotopes of total organic carbon had a good correlation with trophic level.Variations in fatty acid compositions among different species were observed but were unclear.Different dietary structures could be traced from molecular isotopes of selected fatty acids in the Shiba shrimp(Matapenaeus joyneri),the coastal mud shrimp(Solenocera crassicomis) and the northern Maoxia shrimp(Acetes chinensis).Both M.joyneri and S.crassicomis are mainly benthos feeders,while A.chinensis is a pelagic species,although they have a similar fatty acid composition.There was a good correlation for isotopes of arachidonic acid(C20:4n6;ARA) and docosahexaenoic acid(C22:6n3;DHA)among pelagic species from higher trophic levels.The isotopic compositions of DHA in benthic species were more negative than those of pelagic species at the same trophic level.The fact that the diet of benthic species contains more degraded items,the carbon isotopes of which are derived from a large biochemical fraction,may be the reason for this variation.A comparative study of benthic and pelagic species demonstrated the different carbon sources in potential food items and the presence of a more complex system at the watersediment interface.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
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
Because literatures about the lipid compositions of modern soils in karst areas are scarce, we have studied the soil horizons overlying the Heshang （和尚） Cave that has provided paleoclimate records from speleothem ...Because literatures about the lipid compositions of modern soils in karst areas are scarce, we have studied the soil horizons overlying the Heshang （和尚） Cave that has provided paleoclimate records from speleothem lipid contents. Our analysis reveals a series of n-alkanes, free fatty acids, n-alkanols and n-alkan-2-ones distribution and relative abundance changing with the depth, and in which the ratios of the lower molecular weight to higher molecular weight n-alkanes, free fatty acids, n-alkanols and n-alkan-2-ones have a peak at a subsurface depth of 5 to 10 cm. An accompanying peakin 17β（H）, 21β（H）-hop-22（29）-ene （diploptene） and a shift to less negative n-alkane carbon isotopic values also identify this layer in the karst soil. This pattern indicates the existence of a subsurface soil layer in which the microorgan- isms that produce these compounds are espe- cially abundant. The carbon isotopic values of individual plant wax n-alkanes are about 3%0 greater at the base of the 30- to 40-cm soil profile than in the surface layer, probably as a result ofselective microbial degradation of n-alkanes from different primary sources. The lipids and carbon iso- topic values of individual plant wax n-alkanes study of the overlying soil show a strong microbial activity in this karst soil and help in interpreting the lipid compositions and specific carbon isotopic value of n-alkanes of the stalagmites of the Heshang Cave for paleoenvironmental reconstructions.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
Biodegradation of lower chlorinated benzenes(tri-, di-and monochlorobenzene) was assessed at a coastal aquifer contaminated with multiple chlorinated aromatic hydrocarbons. Field-derived microcosms, established with g...Biodegradation of lower chlorinated benzenes(tri-, di-and monochlorobenzene) was assessed at a coastal aquifer contaminated with multiple chlorinated aromatic hydrocarbons. Field-derived microcosms, established with groundwater from the source zone and amended with a mixture of lower chlorinated benzenes, evidenced biodegradation of monochlorobenzene(MCB) and 1,4-dichlorobenzene(1,4-DCB) in aerobic microcosms,whereas the addition of lactate in anaerobic microcosms did not enhance anaerobic reductive dechlorination. Aerobic microcosms established with groundwater from the plume consumed several doses of MCB and concomitantly degraded the three isomers of dichlorobenzene with no observable inhibitory effect. In the light of these results, we assessed the applicability of compound stable isotope analysis to monitor a potential aerobic remediation treatment of MCB and 1,4-DCB in this site. The carbon isotopic fractionation factors(ε) obtained from field-derived microcosms were-0.7‰ ± 0.1 ‰ and-1.0‰ ± 0.2 ‰ for MCB and1,4-DCB, respectively. For 1,4-DCB, the carbon isotope fractionation during aerobic biodegradation was reported for the first time. The weak carbon isotope fractionation values for the aerobic pathway would only allow tracing of in situ degradation in aquifer parts with high extent of biodegradation. However, based on the carbon isotope effects measured in this and previous studies, relatively high carbon isotope shifts(i.e., Δδ13C > 4.0 ‰) of MCB or 1,4-DCB in contaminated groundwater would suggest that their biodegradation is controlled by anaerobic reductive dechlorination.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
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
Extraterrestrial dust exhibits a wide range of textural,chemical and oxygen isotopic compositions due to the heterogeneity of their precursors and modification during atmospheric entry.Experimental heating provides an...Extraterrestrial dust exhibits a wide range of textural,chemical and oxygen isotopic compositions due to the heterogeneity of their precursors and modification during atmospheric entry.Experimental heating provides an opportunity to investigate the relationship between thermal processing and micrometeorite composition for a known precursor material.We conducted experiments to simulate the atmospheric entry of micrometeorites(MMs)using controlled,short-duration(10-50 s)flash heating(400-1600℃)of CI chondrite chips(<1500µm)in atmospheric air(1 bar,21%O2)combined with microanalysis(textures,chemical and isotopic compositions)of the experimental products.The heated chips closely resemble natural samples,with materials similar to unmelted MMs,partially melted(scoriaceous)MMs and fully melted cosmic spherules produced.We reproduced several key features such as dehydration cracks,magnetite rims,volatile gas release,vesicle formation and coalescence,melting and quench cooling.Our parameter space allows for discriminating peak temperature and heating duration effects.Peak temperature is the first-order control on MM mineralogy,while heating duration controls vesicle coalescence and homogenization.When compared against previous heating experiments,our data demonstrates that CI chondrite dust is more thermally resistant,relative to CM chondrite dust,by approximately+200℃.The 207 measurement of O-isotopes allows,for the first time,petrographic effects(such as volatile degassing and melting)to be correlated against bulk O-isotope evolution.Our results demonstrate findings applicable to CI chondrites and potentially to all fine-grained hydrated carbonaceous chondrite dust grains:(1)O-isotope variations arising during sub-solidus heating are dominated by the release of water from phyllosilicates,forcing the residual MM composition towards its anhydrous precursor composition.(2)Oxygen isotope compositions undergo the most significant changes at supra-solidus temperatures.As previously demonstrated and now empirically confirmed,most of these changes are driven by a mass-dependent fractionation effect caused by evaporation,which shifts residual rock compositions toward heavier values.Mixing with atmospheric air alters compositions toward the terrestrial fractionation line.Notably,these two processes do not begin simultaneously.Our data indicate that at 1200℃,isotopic evolution is dominated by evaporative mass loss.However,at higher temperatures(1400-1600℃),both pronounced evaporation and mixing with atmospheric oxygen become active,resulting in a more complex isotopic signature.(3)The total change in Δ17O during heating up to 1600℃is<3‰and in most scenarios<2‰.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 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
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
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
Marine carbonates,the major carrier of carbon upon the upper crust,can be subducted into the Earth’s interior along with oceanic crust,and then returned to the surface through magmatism,which constitute the deep carb...Marine carbonates,the major carrier of carbon upon the upper crust,can be subducted into the Earth’s interior along with oceanic crust,and then returned to the surface through magmatism,which constitute the deep carbon cycle.This process plays an important role in modulating the CO_(2) concentrations in the atmosphere over geologic time,and thus the forming of the habitable earth.Therefore,identifying recycled marine carbonates in the mantle is critical to well understand the global deep carbon cycle.Calcium is one of the major constituent cations in marine carbonates and its isotopes may be a potential tracer for recycled marine carbonates in the mantle.To further evaluate the capability and challenges of Ca isotopes as such a geochemical tracer,we reviewed the Ca isotopic compositions in important reservoirs and the behavior of Ca isotopes during high-temperature geological processes that are related to the deep carbon cycle,including plate subduction,mantle metasomatism,mantle partial melting,magma differentiation,etc.Available studies show that carbonate-rich marine sediments have significantly lowerδ^(44/40) Ca than the Earth mantle,and metasomatism by such recycled materials can cause lighter Ca isotopic compositions in deep mantle-derived rocks than those of the depleted mantle and mid ocean ridge basalts.However,the Ca isotopic fractionation during partial melting of mantle peridotites is small(~0.10‰)and the Ca isotopic fractionation during plate subduction and intermediate-mafic magma evolution is indistinguishable.These investigations suggest that Ca isotopes have great advances in tracing such recycled materials in the mantle.However,other processes(such as the influence by partial melts of eclogites)may induce similar effects on mantle-derived rocks as subducted marine carbonates but still remains debated,and thus further investigations are strongly needed in the future.展开更多
0 INTRODUCTION Tin(Sn)deposits are genetically associated with reduced,crust-derived magmas where Sn is incompatible(as Sn^(2+))and tends to enrich in residual melts during magma evolution(e.g.,Lehmann,2021;Linnen et ...0 INTRODUCTION Tin(Sn)deposits are genetically associated with reduced,crust-derived magmas where Sn is incompatible(as Sn^(2+))and tends to enrich in residual melts during magma evolution(e.g.,Lehmann,2021;Linnen et al.,1995).In contrast,copper(Cu)deposits are typically related to oxidized,mantle-derived magmas where Cu is incompatible because sulfur(S)occurs as sulfate(e.g.,Deng et al.,2023;Sillitoe and Lehmann,2022;Jugo,2009).Thus,Sn and Cu mineralization are rarely coexisting in a single magmatic-hydrothermal deposit(Sillitoe and Lehmann,2022).展开更多
The tectonic evolution of Borneo and the affiliation between Southern and Northern Borneo remains unclear.The Rajang and Crocker Fan sediments,as one of the largest ancient submarine fans in Southeast Asia have witnes...The tectonic evolution of Borneo and the affiliation between Southern and Northern Borneo remains unclear.The Rajang and Crocker Fan sediments,as one of the largest ancient submarine fans in Southeast Asia have witnessed the tectonic evolution of Borneo since at least the late Mesozoic.In this study,we present laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)U-Pb dating and Hf isotopic results of detrital zircons from the Trusmadi and Crocker formations within the Crocker Fan of Sabah,Northern Borneo.Our results,coupled with previous data,show that the Crocker Fan sediments in Sabah of Northern Borneo display similar age spectra to the Rajang Fan sediments in Sarawak of Central Borneo,with two major age clusters at 130-80 and 280-200 Ma.Further provenance analysis based on mineral shape with a prismatic characteristic and similar detrital zircon Hf isotopes of the two formations illustrates that the Jurassic-Cretaceous and partly Triassic detrital zircons of the Crocker and Rajang Fan sediments were derived from the erosion of contemporaneous magmatic rocks;part of Permian-Triassic ones could be the recycling of the Jurassic deposits in SW Borneo.The initial provenance of these Permian-Triassic detritus could be synchronous magmatic rocks in the Tin belt of the Malay Peninsula.Combining with previous data,we propose that the entire Borneo continent,including both Southern and Northern Borneo,developed a common Mesozoic continental magmatic arc.Moreover,we postulate that the Rajang and Crocker fans formed in a fore-arc extensional rift basin related to the retreat of the subducted Paleo-Pacific Plate beneath the Northern Borneo margin.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
Geogas survey is an unconventional geochemical prospecting method that has proven particularly effective in exploring concealed ore deposits.However,its application in covered areas has been questioned due to the lack...Geogas survey is an unconventional geochemical prospecting method that has proven particularly effective in exploring concealed ore deposits.However,its application in covered areas has been questioned due to the lack of a confirmed geogas formation mechanism.Investigating the sources of geogas anomalies can help clarify this mechanism.This study focuses on the Bairendaba silver-polymetallic deposit,located in a grassland-covered area.Tracer research was conducted on lead isotope compositions in the mining area by analyzing various solid media(soil,rocks,ores)and geogas samples.The results revealed considerable differences in lead isotope compositions between background geogas samples and solid media.Furthermore,the lead isotope compositions of anomalous geogas samples differed markedly from those of background samples.These anomalous samples are located closer to the ore body,suggesting that ore-derived lead is incorporated into the geogas.The anomalous lead in geogas is inferred to originate from deep,concealed ore bodies.This study provides a theoretical basis for applying geogas surveys in mineral exploration within covered terrains.展开更多
基金Supported by the National Basic Research Program of China(973 Program)(Nos.2011CB409801,2014CB441502)
文摘The composition and compound-specific isotopes of fatty acids were studied within food webs in the East China Sea.Lipid-normalized stable carbon isotopes of total organic carbon had a good correlation with trophic level.Variations in fatty acid compositions among different species were observed but were unclear.Different dietary structures could be traced from molecular isotopes of selected fatty acids in the Shiba shrimp(Matapenaeus joyneri),the coastal mud shrimp(Solenocera crassicomis) and the northern Maoxia shrimp(Acetes chinensis).Both M.joyneri and S.crassicomis are mainly benthos feeders,while A.chinensis is a pelagic species,although they have a similar fatty acid composition.There was a good correlation for isotopes of arachidonic acid(C20:4n6;ARA) and docosahexaenoic acid(C22:6n3;DHA)among pelagic species from higher trophic levels.The isotopic compositions of DHA in benthic species were more negative than those of pelagic species at the same trophic level.The fact that the diet of benthic species contains more degraded items,the carbon isotopes of which are derived from a large biochemical fraction,may be the reason for this variation.A comparative study of benthic and pelagic species demonstrated the different carbon sources in potential food items and the presence of a more complex system at the watersediment interface.
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.
基金supported by the National Natural Science Foundation of China (Nos. 40572098, 40525008, 40621002,40531004)the 111 Project (No. B08030)
文摘Because literatures about the lipid compositions of modern soils in karst areas are scarce, we have studied the soil horizons overlying the Heshang （和尚） Cave that has provided paleoclimate records from speleothem lipid contents. Our analysis reveals a series of n-alkanes, free fatty acids, n-alkanols and n-alkan-2-ones distribution and relative abundance changing with the depth, and in which the ratios of the lower molecular weight to higher molecular weight n-alkanes, free fatty acids, n-alkanols and n-alkan-2-ones have a peak at a subsurface depth of 5 to 10 cm. An accompanying peakin 17β（H）, 21β（H）-hop-22（29）-ene （diploptene） and a shift to less negative n-alkane carbon isotopic values also identify this layer in the karst soil. This pattern indicates the existence of a subsurface soil layer in which the microorgan- isms that produce these compounds are espe- cially abundant. The carbon isotopic values of individual plant wax n-alkanes are about 3%0 greater at the base of the 30- to 40-cm soil profile than in the surface layer, probably as a result ofselective microbial degradation of n-alkanes from different primary sources. The lipids and carbon iso- topic values of individual plant wax n-alkanes study of the overlying soil show a strong microbial activity in this karst soil and help in interpreting the lipid compositions and specific carbon isotopic value of n-alkanes of the stalagmites of the Heshang Cave for paleoenvironmental reconstructions.
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 Catalan Water Agency (No. CTN1900901)supported by the projects CGL2017–82331-R (Spanish Ministry of Economy and Competitiveness)2017SGR 1733 (Catalan Government)。
文摘Biodegradation of lower chlorinated benzenes(tri-, di-and monochlorobenzene) was assessed at a coastal aquifer contaminated with multiple chlorinated aromatic hydrocarbons. Field-derived microcosms, established with groundwater from the source zone and amended with a mixture of lower chlorinated benzenes, evidenced biodegradation of monochlorobenzene(MCB) and 1,4-dichlorobenzene(1,4-DCB) in aerobic microcosms,whereas the addition of lactate in anaerobic microcosms did not enhance anaerobic reductive dechlorination. Aerobic microcosms established with groundwater from the plume consumed several doses of MCB and concomitantly degraded the three isomers of dichlorobenzene with no observable inhibitory effect. In the light of these results, we assessed the applicability of compound stable isotope analysis to monitor a potential aerobic remediation treatment of MCB and 1,4-DCB in this site. The carbon isotopic fractionation factors(ε) obtained from field-derived microcosms were-0.7‰ ± 0.1 ‰ and-1.0‰ ± 0.2 ‰ for MCB and1,4-DCB, respectively. For 1,4-DCB, the carbon isotope fractionation during aerobic biodegradation was reported for the first time. The weak carbon isotope fractionation values for the aerobic pathway would only allow tracing of in situ degradation in aquifer parts with high extent of biodegradation. However, based on the carbon isotope effects measured in this and previous studies, relatively high carbon isotope shifts(i.e., Δδ13C > 4.0 ‰) of MCB or 1,4-DCB in contaminated groundwater would suggest that their biodegradation is controlled by anaerobic reductive dechlorination.
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(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ISRO-RESPOND GAP3332 and PMN-MOES GAP2175 Project support this work.
文摘Extraterrestrial dust exhibits a wide range of textural,chemical and oxygen isotopic compositions due to the heterogeneity of their precursors and modification during atmospheric entry.Experimental heating provides an opportunity to investigate the relationship between thermal processing and micrometeorite composition for a known precursor material.We conducted experiments to simulate the atmospheric entry of micrometeorites(MMs)using controlled,short-duration(10-50 s)flash heating(400-1600℃)of CI chondrite chips(<1500µm)in atmospheric air(1 bar,21%O2)combined with microanalysis(textures,chemical and isotopic compositions)of the experimental products.The heated chips closely resemble natural samples,with materials similar to unmelted MMs,partially melted(scoriaceous)MMs and fully melted cosmic spherules produced.We reproduced several key features such as dehydration cracks,magnetite rims,volatile gas release,vesicle formation and coalescence,melting and quench cooling.Our parameter space allows for discriminating peak temperature and heating duration effects.Peak temperature is the first-order control on MM mineralogy,while heating duration controls vesicle coalescence and homogenization.When compared against previous heating experiments,our data demonstrates that CI chondrite dust is more thermally resistant,relative to CM chondrite dust,by approximately+200℃.The 207 measurement of O-isotopes allows,for the first time,petrographic effects(such as volatile degassing and melting)to be correlated against bulk O-isotope evolution.Our results demonstrate findings applicable to CI chondrites and potentially to all fine-grained hydrated carbonaceous chondrite dust grains:(1)O-isotope variations arising during sub-solidus heating are dominated by the release of water from phyllosilicates,forcing the residual MM composition towards its anhydrous precursor composition.(2)Oxygen isotope compositions undergo the most significant changes at supra-solidus temperatures.As previously demonstrated and now empirically confirmed,most of these changes are driven by a mass-dependent fractionation effect caused by evaporation,which shifts residual rock compositions toward heavier values.Mixing with atmospheric air alters compositions toward the terrestrial fractionation line.Notably,these two processes do not begin simultaneously.Our data indicate that at 1200℃,isotopic evolution is dominated by evaporative mass loss.However,at higher temperatures(1400-1600℃),both pronounced evaporation and mixing with atmospheric oxygen become active,resulting in a more complex isotopic signature.(3)The total change in Δ17O during heating up to 1600℃is<3‰and in most scenarios<2‰.
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 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 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 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.
基金Supported by the National Natural Science Foundation of China(Nos.42322302,42373048)the Youth Innovation Promotion Association,Chinese Academy of Sciences(No.2022207)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB42020303)the Laoshan Laboratory(No.LSKJ202204100)。
文摘Marine carbonates,the major carrier of carbon upon the upper crust,can be subducted into the Earth’s interior along with oceanic crust,and then returned to the surface through magmatism,which constitute the deep carbon cycle.This process plays an important role in modulating the CO_(2) concentrations in the atmosphere over geologic time,and thus the forming of the habitable earth.Therefore,identifying recycled marine carbonates in the mantle is critical to well understand the global deep carbon cycle.Calcium is one of the major constituent cations in marine carbonates and its isotopes may be a potential tracer for recycled marine carbonates in the mantle.To further evaluate the capability and challenges of Ca isotopes as such a geochemical tracer,we reviewed the Ca isotopic compositions in important reservoirs and the behavior of Ca isotopes during high-temperature geological processes that are related to the deep carbon cycle,including plate subduction,mantle metasomatism,mantle partial melting,magma differentiation,etc.Available studies show that carbonate-rich marine sediments have significantly lowerδ^(44/40) Ca than the Earth mantle,and metasomatism by such recycled materials can cause lighter Ca isotopic compositions in deep mantle-derived rocks than those of the depleted mantle and mid ocean ridge basalts.However,the Ca isotopic fractionation during partial melting of mantle peridotites is small(~0.10‰)and the Ca isotopic fractionation during plate subduction and intermediate-mafic magma evolution is indistinguishable.These investigations suggest that Ca isotopes have great advances in tracing such recycled materials in the mantle.However,other processes(such as the influence by partial melts of eclogites)may induce similar effects on mantle-derived rocks as subducted marine carbonates but still remains debated,and thus further investigations are strongly needed in the future.
基金financially supported by the National Natural Science Foundation of China(Nos.42002080,42302092)the Guangxi Technology Base and Talent Project(No.Guike AD20238013)the Provincial Natural Science Foundation of Hunan(No.2024JJ5394)。
文摘0 INTRODUCTION Tin(Sn)deposits are genetically associated with reduced,crust-derived magmas where Sn is incompatible(as Sn^(2+))and tends to enrich in residual melts during magma evolution(e.g.,Lehmann,2021;Linnen et al.,1995).In contrast,copper(Cu)deposits are typically related to oxidized,mantle-derived magmas where Cu is incompatible because sulfur(S)occurs as sulfate(e.g.,Deng et al.,2023;Sillitoe and Lehmann,2022;Jugo,2009).Thus,Sn and Cu mineralization are rarely coexisting in a single magmatic-hydrothermal deposit(Sillitoe and Lehmann,2022).
基金jointly supported by the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources,Xiamen(No.2018002)the Guangxi Natural Science Fundation(No.2022GXNSFBA035588)+1 种基金the National Natural Science Foundation of China(Nos.41506050,41402193)the Scientific Research Foundation of Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration(No.19-185-17-09)。
文摘The tectonic evolution of Borneo and the affiliation between Southern and Northern Borneo remains unclear.The Rajang and Crocker Fan sediments,as one of the largest ancient submarine fans in Southeast Asia have witnessed the tectonic evolution of Borneo since at least the late Mesozoic.In this study,we present laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)U-Pb dating and Hf isotopic results of detrital zircons from the Trusmadi and Crocker formations within the Crocker Fan of Sabah,Northern Borneo.Our results,coupled with previous data,show that the Crocker Fan sediments in Sabah of Northern Borneo display similar age spectra to the Rajang Fan sediments in Sarawak of Central Borneo,with two major age clusters at 130-80 and 280-200 Ma.Further provenance analysis based on mineral shape with a prismatic characteristic and similar detrital zircon Hf isotopes of the two formations illustrates that the Jurassic-Cretaceous and partly Triassic detrital zircons of the Crocker and Rajang Fan sediments were derived from the erosion of contemporaneous magmatic rocks;part of Permian-Triassic ones could be the recycling of the Jurassic deposits in SW Borneo.The initial provenance of these Permian-Triassic detritus could be synchronous magmatic rocks in the Tin belt of the Malay Peninsula.Combining with previous data,we propose that the entire Borneo continent,including both Southern and Northern Borneo,developed a common Mesozoic continental magmatic arc.Moreover,we postulate that the Rajang and Crocker fans formed in a fore-arc extensional rift basin related to the retreat of the subducted Paleo-Pacific Plate beneath the Northern Borneo margin.
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.
基金supported by Key Laboratory of Ionic Rare Earth Resources and Environment,Ministry of Natural Resources(No.2023IRERE102)National Nonprofit Institute Research Grant of Institute of Geophysical and Geochemical Exploration(AS2022P03)。
文摘Geogas survey is an unconventional geochemical prospecting method that has proven particularly effective in exploring concealed ore deposits.However,its application in covered areas has been questioned due to the lack of a confirmed geogas formation mechanism.Investigating the sources of geogas anomalies can help clarify this mechanism.This study focuses on the Bairendaba silver-polymetallic deposit,located in a grassland-covered area.Tracer research was conducted on lead isotope compositions in the mining area by analyzing various solid media(soil,rocks,ores)and geogas samples.The results revealed considerable differences in lead isotope compositions between background geogas samples and solid media.Furthermore,the lead isotope compositions of anomalous geogas samples differed markedly from those of background samples.These anomalous samples are located closer to the ore body,suggesting that ore-derived lead is incorporated into the geogas.The anomalous lead in geogas is inferred to originate from deep,concealed ore bodies.This study provides a theoretical basis for applying geogas surveys in mineral exploration within covered terrains.
