Cadmium(Cd)isotopes in seawater have been proven as an important geochemical tool for tracing ocean Cd circulation in the modern ocean.In this study,we evaluated a new method to separate Cd(*60 ng)from seawater using ...Cadmium(Cd)isotopes in seawater have been proven as an important geochemical tool for tracing ocean Cd circulation in the modern ocean.In this study,we evaluated a new method to separate Cd(*60 ng)from seawater using Chelex resin(1.0 g)coupled with AG-MP-1M resin.The results show that the Chelex resin is suffi-cient to remove Cd from Na and Mg matrix with Cd recoveries at 98.3±3.5%(2SD,N=6);while AG-MP-1M resin could separate Cd from the residual Na,Mg,and isobaric inferences.The total Cd recoveries of the method are 96.3±1.5%(2SD;N=4)and the salinity of the samples has no significant impacts on Cd recovery.Cd isotope ratios were measured using a Nu PlasmaⅢMC-ICP-MS and^(111)Cd–^(110)Cd double spike technique.By comparing theδ^(114/110)Cd values(0.00±0.06%)of synthetic seawaters doped with Cd isotope standard(NIST-3108;treated by Chelex+AG-MP-1M resin)and the reference value(-0.00%),no variations were observed.We also analyzed the Cd isotope compositions of three deep seawaters from a column at the Southwest Indian Ocean Ridges(SWIR).Theδ^(114/110)Cd values of the col-umn are decreased from 1.05±0.05%at 3200 m to 0.36±0.05%at 2800 m,differing from reportedδ^(114/110)Cd values of deep seawater in other oceans.Considering the spatial distance between the column and active hydrothermal vents in SWIR(-13 km),we propose that such positiveδ^(114/110)Cd values of deep seawater were likely contaminated by vent fluids,which could provide heavy Cd isotope to deep seawaters.This study demon-strates that Cd isotope is more sufficient to distinguish the impact of plumes on deep seawater.展开更多
The Sichuan–Yunnan–Guizhou(SYG)Zn–Pb metallogenic zone in SW China contains>400 carbonatehosted hydrothermal Zn–Pb deposits.Some of these,such as the Huize,Tianbaoshan,and Daliangzi deposits,are super-large dep...The Sichuan–Yunnan–Guizhou(SYG)Zn–Pb metallogenic zone in SW China contains>400 carbonatehosted hydrothermal Zn–Pb deposits.Some of these,such as the Huize,Tianbaoshan,and Daliangzi deposits,are super-large deposits with significant reserves of Cd,Ge,and Ag.However,the sources of these metals remain controversial.This study investigated the Cd isotopic geochemistry of the Huize deposit,the largest Zn–Pb deposit in the SYG area.Sphalerites formed at three stages in the deposit have different colors:black or dark brown(Stage I),red(Stage II),and light-yellow(Stage III).The d^(114/110)Cd values of the sphalerites are in the order Stage III<Stage I<Stage II.Kinetic isotopic fractionation is likely the key factor causing the lower δ^(114/110)Cd values in the early formed Stage I sphalerites than in laterformed Stage II sphalerites,with cooling of ore-forming fluids being responsible for the still lower values of the Stage III sphalerites.In galena,the δ^(114/110)Cd values are inversely correlated with Cd contents and tend to be higher in high-Zn galena.We speculate that Cd isotopic fractionation was significant during the precipitation of sphalerite and galena,with light Cd isotopes being enriched in galena rather than sphalerite.Comparison of the Cd isotopic signatures and Zn/Cd ratios of different endmembers suggests that the δ^(114/110)Cd values and Zn/Cd ratios of sphalerite from the Huize deposit,as well as other largescale deposits from the SYG area,are lie in those range of Emeishan basalts and sedimentary rocks and the mean δ^(114/110)Cd values of these deposits show good negative correlation with 1/Cd,suggesting that the ore-forming materials of these deposits were derived from the mixing of Emeishan basalts and sedimentary rocks.This study demonstrates that Cd isotopes can be useful proxies in elucidating ore genesis in large Zn–Pb deposits.展开更多
Cd isotopes exhibit multiphonon excitations involving particle-hole configurations,which makes them potential candidates for studying the coexistence of normal and intruder states.However,the presence of intruder stat...Cd isotopes exhibit multiphonon excitations involving particle-hole configurations,which makes them potential candidates for studying the coexistence of normal and intruder states.However,the presence of intruder states in Cd isotopes is more pronounced.Therefore,the two-state mixing model is suitable for explaining the band mixing observed in this study.This study utilizes a simple two-state mixing model to analyze the ground and excited states of Cd isotopes.The mixing between the lowest vibrational and rotational 0^(+)and 2^(+)states and the sum of the second and third states of each J^(p)are estimated and compared.The calculations indicate that the mixing is more significant in^(114)Cd than in^(116)Cd.展开更多
Up to now, the evaporation and condensation, as well as the biological absorption and inorganic absorptions, have been proved to be major factors in Cd isotope fractionation. And Cd isotopes have been widely applied i...Up to now, the evaporation and condensation, as well as the biological absorption and inorganic absorptions, have been proved to be major factors in Cd isotope fractionation. And Cd isotopes have been widely applied in studies on the universal evolution and marine environment and so on. However, only a few researches have been conducted in applying Cd isotopes to trace the source of metallogenic material and the evolution of the ore-forming fluid in a complex mineralization environment, especially in a hydrothermal ore-formation system. We measured the Cd isotopic compositions of sphalerite, galena, and ores from five lead-zinc deposits in SW China, and found that the ~14/11~Cd values varied from -1.53%o to 0.34%0, with a total range of 1.87%o, which is greater than most of measured geological samples. Meanwhile, through contrasting the Cd content with Cd isotopic compositions of different deposits, it may be concluded that different genetic lead-zinc deposits have different Cd content and isotopic compositions, which could be a tool for the studies on the origin of ore deposits. Also, the biominera]iza- tion and crystal fractionation may also result in Cd isotope fractionation. In a word, although the research of Cd isotopes is presently at the preliminary stage （especially in hydrothermal ore-formation system）, this study demonstrated that Cd isotopes can give a clue in tracing the evolution of ore-forming fluid and metallogenic environment.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42073010)the Key Research and Development Program of Yunnan Province(Grant No.202103AQ100003)a special fund managed by the State Key Laboratory of Ore Deposit Geochemistry,Chinese Academy of Sciences.
文摘Cadmium(Cd)isotopes in seawater have been proven as an important geochemical tool for tracing ocean Cd circulation in the modern ocean.In this study,we evaluated a new method to separate Cd(*60 ng)from seawater using Chelex resin(1.0 g)coupled with AG-MP-1M resin.The results show that the Chelex resin is suffi-cient to remove Cd from Na and Mg matrix with Cd recoveries at 98.3±3.5%(2SD,N=6);while AG-MP-1M resin could separate Cd from the residual Na,Mg,and isobaric inferences.The total Cd recoveries of the method are 96.3±1.5%(2SD;N=4)and the salinity of the samples has no significant impacts on Cd recovery.Cd isotope ratios were measured using a Nu PlasmaⅢMC-ICP-MS and^(111)Cd–^(110)Cd double spike technique.By comparing theδ^(114/110)Cd values(0.00±0.06%)of synthetic seawaters doped with Cd isotope standard(NIST-3108;treated by Chelex+AG-MP-1M resin)and the reference value(-0.00%),no variations were observed.We also analyzed the Cd isotope compositions of three deep seawaters from a column at the Southwest Indian Ocean Ridges(SWIR).Theδ^(114/110)Cd values of the col-umn are decreased from 1.05±0.05%at 3200 m to 0.36±0.05%at 2800 m,differing from reportedδ^(114/110)Cd values of deep seawater in other oceans.Considering the spatial distance between the column and active hydrothermal vents in SWIR(-13 km),we propose that such positiveδ^(114/110)Cd values of deep seawater were likely contaminated by vent fluids,which could provide heavy Cd isotope to deep seawaters.This study demon-strates that Cd isotope is more sufficient to distinguish the impact of plumes on deep seawater.
基金This project was financially supported by the National Natural Science Foundation of China(Nos.41773012,42073010)a special fund managed by the State Key Laboratory of Ore Deposit Geochemistry,Chinese Academy of SciencesScience and Technology Foundation of Guizhou Province([2019]1459)。
文摘The Sichuan–Yunnan–Guizhou(SYG)Zn–Pb metallogenic zone in SW China contains>400 carbonatehosted hydrothermal Zn–Pb deposits.Some of these,such as the Huize,Tianbaoshan,and Daliangzi deposits,are super-large deposits with significant reserves of Cd,Ge,and Ag.However,the sources of these metals remain controversial.This study investigated the Cd isotopic geochemistry of the Huize deposit,the largest Zn–Pb deposit in the SYG area.Sphalerites formed at three stages in the deposit have different colors:black or dark brown(Stage I),red(Stage II),and light-yellow(Stage III).The d^(114/110)Cd values of the sphalerites are in the order Stage III<Stage I<Stage II.Kinetic isotopic fractionation is likely the key factor causing the lower δ^(114/110)Cd values in the early formed Stage I sphalerites than in laterformed Stage II sphalerites,with cooling of ore-forming fluids being responsible for the still lower values of the Stage III sphalerites.In galena,the δ^(114/110)Cd values are inversely correlated with Cd contents and tend to be higher in high-Zn galena.We speculate that Cd isotopic fractionation was significant during the precipitation of sphalerite and galena,with light Cd isotopes being enriched in galena rather than sphalerite.Comparison of the Cd isotopic signatures and Zn/Cd ratios of different endmembers suggests that the δ^(114/110)Cd values and Zn/Cd ratios of sphalerite from the Huize deposit,as well as other largescale deposits from the SYG area,are lie in those range of Emeishan basalts and sedimentary rocks and the mean δ^(114/110)Cd values of these deposits show good negative correlation with 1/Cd,suggesting that the ore-forming materials of these deposits were derived from the mixing of Emeishan basalts and sedimentary rocks.This study demonstrates that Cd isotopes can be useful proxies in elucidating ore genesis in large Zn–Pb deposits.
基金Supported by the National Natural Science Foundation of China(12250410254)the Zhejiang Sci-Tech University Intramural Grant(23062211-Y)。
文摘Cd isotopes exhibit multiphonon excitations involving particle-hole configurations,which makes them potential candidates for studying the coexistence of normal and intruder states.However,the presence of intruder states in Cd isotopes is more pronounced.Therefore,the two-state mixing model is suitable for explaining the band mixing observed in this study.This study utilizes a simple two-state mixing model to analyze the ground and excited states of Cd isotopes.The mixing between the lowest vibrational and rotational 0^(+)and 2^(+)states and the sum of the second and third states of each J^(p)are estimated and compared.The calculations indicate that the mixing is more significant in^(114)Cd than in^(116)Cd.
基金supported by National Basic Research Program of China(Grant No.2009CB421005)Chinese Academy of Sciences for Key Topics in Innovation Engineering(Grant No.KZCX2-YW-Q04-01)
文摘Up to now, the evaporation and condensation, as well as the biological absorption and inorganic absorptions, have been proved to be major factors in Cd isotope fractionation. And Cd isotopes have been widely applied in studies on the universal evolution and marine environment and so on. However, only a few researches have been conducted in applying Cd isotopes to trace the source of metallogenic material and the evolution of the ore-forming fluid in a complex mineralization environment, especially in a hydrothermal ore-formation system. We measured the Cd isotopic compositions of sphalerite, galena, and ores from five lead-zinc deposits in SW China, and found that the ~14/11~Cd values varied from -1.53%o to 0.34%0, with a total range of 1.87%o, which is greater than most of measured geological samples. Meanwhile, through contrasting the Cd content with Cd isotopic compositions of different deposits, it may be concluded that different genetic lead-zinc deposits have different Cd content and isotopic compositions, which could be a tool for the studies on the origin of ore deposits. Also, the biominera]iza- tion and crystal fractionation may also result in Cd isotope fractionation. In a word, although the research of Cd isotopes is presently at the preliminary stage （especially in hydrothermal ore-formation system）, this study demonstrated that Cd isotopes can give a clue in tracing the evolution of ore-forming fluid and metallogenic environment.
