The Sichuan-Yunnan-Guizhou(SYG)metallogenic province of southwest China is one of the most important Zn-Pb ore zones in China,with^200 Mt ZnPb ores at mean grades of 10 wt.%Zn and 5 wt.%Pb.The source and mechanism of ...The Sichuan-Yunnan-Guizhou(SYG)metallogenic province of southwest China is one of the most important Zn-Pb ore zones in China,with^200 Mt ZnPb ores at mean grades of 10 wt.%Zn and 5 wt.%Pb.The source and mechanism of the regional Zn-Pb mineralization remain controversial despite many investigations that have been conducted.The Wusihe Zn-Pb deposit is a representative large-scale Zn-Pb deposit in the northern SYG,which mainly occurs in the Dengying Formation and yields Zn-Pb resources of^3.7 Mt.In this paper,Zn and S isotopes,and Fe and Cd contents of sphalerite from the Wusihe deposit were investigated in an attempt to constrain the controls on Zn and S isotopic variations,the potential sources of ore-forming components,and the possible mineralization mechanisms.Both theδ66Zn andδ34S values in sphalerite from the Wusihe deposit increase systematically from the bottom to the top of the strata-bound orebodies.Such spatial evolution inδ66Zn andδ34S values of sphalerite can be attributed to isotopic Rayleigh fractionation during sphalerite precipitation with temperature variations.The strong correlations between the Zn-S isotopic compositions and Fe-Cd concentrations in sphalerite suggest that their variations were dominated by a similar mechanism.However,the Rayleigh fractionation mechanism cannot explain the spatial variations of Fe and Cd concentrations of sphalerite in this deposit.It is noted that the bottom and top sphalerites from the strata-bound orebodies document contrasting Zn and S isotopic compositions which correspond to the Zn and S isotopic characteristics of basement rocks and host rocks,respectively.Therefore,the mixing of two-source fluids with distinct Zn-S isotopic signatures was responsible for the spatial variations of Zn-S isotopic compositions of sphalerite from the Wusihe deposit.The fluids from basement rocks are characterized by relatively lighter Zn(~0.2‰)and S(~5‰)isotopic compositions while the fluids from host rocks are marked by relatively heavier Zn(~0.6‰)and S(~15‰)isotopic compositions.展开更多
Understanding the controls on seasonal variation of energy partitioning and separation between canopy and soil surface are important for qualifying the vegetation feedback to climate system.Using observed day-to-day v...Understanding the controls on seasonal variation of energy partitioning and separation between canopy and soil surface are important for qualifying the vegetation feedback to climate system.Using observed day-to-day variations of energy balance components including net radiation,sensible heat flux,latent heat flux ground heat flux,and meteorological variables combined with an energy-balanced two-source model,energy partitioning were investigated at six sites in Heihe River Basin from 2014 to 2016.Bowen ratio(β) among the six sites exhibited significant seasonal variations while showed smaller inter-annual fluctuations.All ecosystems exhibit a "U-shaped" pattern,characterized by smaller value of β in growing season,with a minimum value in July,and fluctuating day to day.During the growing season,average Bowen ratio was the highest for the alpine swamp meadow(0.60 ± 0.30),followed by the desert riparian forest Populus euphratica(0.47 ± 0.72),the alpine desert(0.46 ± 0.10),the Tamarix ramosissima desert riparian shrub ecosystem(0.33 ± 0.57),alpine meadow ecosystem(0.32 ± 0.17),and cropland ecosystem(0.27 ± 0.46).The agreement of Bowen ratio between simulated and observed values demonstrated that the two-source model is a promising tool for energy partitioning and separation between canopy and soil surface.The importance of biophysical control explains the convergence of seasonal and annual patterns of Bowen ratio for all ecosystems,and the changes in Bowen ratio showed divergence among varied ecosystems because of different physiological responses to energy flow pathways between canopy and soil surface.展开更多
基金funded by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB18030302)the National Key R&D Program of China (2017YFC0602503)the National Natural Science Foundation of China (U1812402, 41430315, 41573011, 41625006)
文摘The Sichuan-Yunnan-Guizhou(SYG)metallogenic province of southwest China is one of the most important Zn-Pb ore zones in China,with^200 Mt ZnPb ores at mean grades of 10 wt.%Zn and 5 wt.%Pb.The source and mechanism of the regional Zn-Pb mineralization remain controversial despite many investigations that have been conducted.The Wusihe Zn-Pb deposit is a representative large-scale Zn-Pb deposit in the northern SYG,which mainly occurs in the Dengying Formation and yields Zn-Pb resources of^3.7 Mt.In this paper,Zn and S isotopes,and Fe and Cd contents of sphalerite from the Wusihe deposit were investigated in an attempt to constrain the controls on Zn and S isotopic variations,the potential sources of ore-forming components,and the possible mineralization mechanisms.Both theδ66Zn andδ34S values in sphalerite from the Wusihe deposit increase systematically from the bottom to the top of the strata-bound orebodies.Such spatial evolution inδ66Zn andδ34S values of sphalerite can be attributed to isotopic Rayleigh fractionation during sphalerite precipitation with temperature variations.The strong correlations between the Zn-S isotopic compositions and Fe-Cd concentrations in sphalerite suggest that their variations were dominated by a similar mechanism.However,the Rayleigh fractionation mechanism cannot explain the spatial variations of Fe and Cd concentrations of sphalerite in this deposit.It is noted that the bottom and top sphalerites from the strata-bound orebodies document contrasting Zn and S isotopic compositions which correspond to the Zn and S isotopic characteristics of basement rocks and host rocks,respectively.Therefore,the mixing of two-source fluids with distinct Zn-S isotopic signatures was responsible for the spatial variations of Zn-S isotopic compositions of sphalerite from the Wusihe deposit.The fluids from basement rocks are characterized by relatively lighter Zn(~0.2‰)and S(~5‰)isotopic compositions while the fluids from host rocks are marked by relatively heavier Zn(~0.6‰)and S(~15‰)isotopic compositions.
基金The Strategic Priority Research Program of Chinese Academy of Sciences,No.XDA20100102National Natural Science Foundation of China,No.41730854,No.41671019Projects by the State Key Laboratory of Earth Surface Processes and Resource Ecology
文摘Understanding the controls on seasonal variation of energy partitioning and separation between canopy and soil surface are important for qualifying the vegetation feedback to climate system.Using observed day-to-day variations of energy balance components including net radiation,sensible heat flux,latent heat flux ground heat flux,and meteorological variables combined with an energy-balanced two-source model,energy partitioning were investigated at six sites in Heihe River Basin from 2014 to 2016.Bowen ratio(β) among the six sites exhibited significant seasonal variations while showed smaller inter-annual fluctuations.All ecosystems exhibit a "U-shaped" pattern,characterized by smaller value of β in growing season,with a minimum value in July,and fluctuating day to day.During the growing season,average Bowen ratio was the highest for the alpine swamp meadow(0.60 ± 0.30),followed by the desert riparian forest Populus euphratica(0.47 ± 0.72),the alpine desert(0.46 ± 0.10),the Tamarix ramosissima desert riparian shrub ecosystem(0.33 ± 0.57),alpine meadow ecosystem(0.32 ± 0.17),and cropland ecosystem(0.27 ± 0.46).The agreement of Bowen ratio between simulated and observed values demonstrated that the two-source model is a promising tool for energy partitioning and separation between canopy and soil surface.The importance of biophysical control explains the convergence of seasonal and annual patterns of Bowen ratio for all ecosystems,and the changes in Bowen ratio showed divergence among varied ecosystems because of different physiological responses to energy flow pathways between canopy and soil surface.
