AMD(Acid Mine Drainage)-type acidic groundwater (pH<4) from oxidizing sulfide tailings in BS nickel mine (Western Australia) is of higher total rare earth element(REE) contents and Ce enrichment (PAAS normalization...AMD(Acid Mine Drainage)-type acidic groundwater (pH<4) from oxidizing sulfide tailings in BS nickel mine (Western Australia) is of higher total rare earth element(REE) contents and Ce enrichment (PAAS normalization), different from setting groundwater (pH>6.5, with lower total REE contents, Ce depletion). While the AMD contaminated groundwater (pH=4.0-6.5) around tailings pond is characterized by transition from acidic to setting groundwater in total REE content, and associated with Ce depletion (like setting groundwater). The light REE in all type groundwater shows up depletion, but its depleted extent in acidic groundwater is more remarkable. This work indicates that REE behavior in AMD-type acidic groundwater is controlled mainly by pH value and metal (Al, Mn and Fe) contents. And the critical pH value that affects REE behavior in ground acidic water would be 4, lower than the previous value (pH=5) that has been believed prevalently in surface acidic waters. The pH could affect REE behavior in groundwater by controlling the solubility of metal (Al, Mn and Fe) hydroxides and the valence of cerium. Finally, light REE depletion in acidic groundwater may due to element affinity. High content Al (affinity with heavy REE) and low content Fe (affinity with light REE) may lead to heavy REE enrichment while light REE relative depletion in water.展开更多
The Jinchuan Ni-Cu sulfide deposits,NW China,are hosted in small ultramafic intrusions that were emplaced into Paleoproterozoic metamorphic rocks. The ultramafic intrusions were previously thought to be the segments o...The Jinchuan Ni-Cu sulfide deposits,NW China,are hosted in small ultramafic intrusions that were emplaced into Paleoproterozoic metamorphic rocks. The ultramafic intrusions were previously thought to be the segments of a single elongate intrusion that was dismembered by late faults into eastern and western portions,each of which have distinct stratigraphic sequences.展开更多
The three most crucial factors for the formation of large and super-large magmatic sulfide deposits are： （1） a large volume of mantle-derived mafic-ultramafic magmas that participated in the formation of the deposi...The three most crucial factors for the formation of large and super-large magmatic sulfide deposits are： （1） a large volume of mantle-derived mafic-ultramafic magmas that participated in the formation of the deposits; （2） fractional crystallization and crustal contamination, particularly the input of sulfur from crustal rocks, resulting in sulfide immiscibility and segregation; and （3） the timing of sulfide concentration in the intrusion. The super-large magmatic Ni-Cu sulfide deposits around the world have been found in small mafic-ultramafic intrusions, except for the Sudbury deposit. Studies in the past decade indicated that the intrusions hosting large and super-large magmatic sulfide deposits occur in magma conduits, such as those in China, including Jinchuan （Gansu）, Yangliuping （Sichuan）, Kalatongke （Xinjiang）, and Hongqiling （Jilin）. Magma conduits as open magma systems provide a perfect environment for extensive concentration of immiscible sulfide melts, which have been found to occur along deep regional faults. The origin of many mantle-derived magmas is closely associated with mantle plumes, intracontinental rifts, or post-collisional extension. Although it has been confirmed that sulfide immiscibility results from crustal contamination, grades of sulfide ores are also related to the nature of the parental magmas, the ratio between silicate magma and immiscible sulfide melt, the reaction between the sulfide melts and newly injected silicate magmas, and fractionation of the sulfide melt. The field relationships of the ore-bearing intrusion and the sulfide ore body are controlled by the geological features of the wall rocks. In this paper, we attempt to demonstrate the general characteristics, formation mechanism,tectonic settings, and indicators of magmatic sulfide deposits occurring in magmatic conduits which would provide guidelines for further exploration.展开更多
Pancarli Ni-Cu±(PGE)sulfide deposit occurs in the Neoproterozoic basement complex of the Bitlis massif,which is one of the Andean-type active continental margin fragments with arc-type assemblages represented by ...Pancarli Ni-Cu±(PGE)sulfide deposit occurs in the Neoproterozoic basement complex of the Bitlis massif,which is one of the Andean-type active continental margin fragments with arc-type assemblages represented by the Cadomian orogenic belt.Pancarli sulfides are associated with quartzo-feldspathic gneisses(country rock)and mafic intrusions(host rock).Composed of only semi-massive ore,the Ni-Cu±(PGE)sulfide deposit is a small-scale deposit,and it does not contain net-textured and disseminated ore.The mineral assemblage comprises pyrrhotite,pentlandite,and chalcopyrite.The semi-massive ore samples contain 2.2 wt.%-2.9 wt.%Ni,0.8 wt.%-2.2 wt.%Cu(Cu/(Cu+Ni)=0.2-0.5)and 0.13 wt.%-0.17 wt.%Co.The Cu/Ni ratios(average 0.57)are consistent with the segregation of sulfides from a basaltic magma.Low Pt+Pd100%S values of 0.08 ppm-0.89 ppm,relatively low Pt/Pd ratios of 0.2-1.4,and Pd/Ir ratios of 4.5-39 have also been revealed.These values demonstrate that the magma reached S saturation before its emplacement and the mineralization with high Cu/Pd ratios formed by sulfides segregated from a PGE-depleted magma.δ^34S isotope values(average-3.1‰)of Pancarli sulfides are lower than mantle source.Negativeδ^34S value indicates contamination from surrounding rocks.Concerning the composition,remobilization style and magma type,the Pancarli Ni-Cu±(PGE)sulfide deposit is similar to the deposits associated with Andean-type magmatic arcs located in the convergent plate margin settings.展开更多
基金Project supported by the Science Foundation of Guangxi Province, ChinaProject supported by the Director Fund Project of Key Laboratory of Geological Engineering Center of Guangxi Province, China
文摘AMD(Acid Mine Drainage)-type acidic groundwater (pH<4) from oxidizing sulfide tailings in BS nickel mine (Western Australia) is of higher total rare earth element(REE) contents and Ce enrichment (PAAS normalization), different from setting groundwater (pH>6.5, with lower total REE contents, Ce depletion). While the AMD contaminated groundwater (pH=4.0-6.5) around tailings pond is characterized by transition from acidic to setting groundwater in total REE content, and associated with Ce depletion (like setting groundwater). The light REE in all type groundwater shows up depletion, but its depleted extent in acidic groundwater is more remarkable. This work indicates that REE behavior in AMD-type acidic groundwater is controlled mainly by pH value and metal (Al, Mn and Fe) contents. And the critical pH value that affects REE behavior in ground acidic water would be 4, lower than the previous value (pH=5) that has been believed prevalently in surface acidic waters. The pH could affect REE behavior in groundwater by controlling the solubility of metal (Al, Mn and Fe) hydroxides and the valence of cerium. Finally, light REE depletion in acidic groundwater may due to element affinity. High content Al (affinity with heavy REE) and low content Fe (affinity with light REE) may lead to heavy REE enrichment while light REE relative depletion in water.
文摘The Jinchuan Ni-Cu sulfide deposits,NW China,are hosted in small ultramafic intrusions that were emplaced into Paleoproterozoic metamorphic rocks. The ultramafic intrusions were previously thought to be the segments of a single elongate intrusion that was dismembered by late faults into eastern and western portions,each of which have distinct stratigraphic sequences.
基金supported by 973 Program(2007CB411408)National Natural Science Foundation of China(NSFC) projects (40730420 and 40973038)Chinese Academy of Sciences(KZCX2-YW-Q04)
文摘The three most crucial factors for the formation of large and super-large magmatic sulfide deposits are： （1） a large volume of mantle-derived mafic-ultramafic magmas that participated in the formation of the deposits; （2） fractional crystallization and crustal contamination, particularly the input of sulfur from crustal rocks, resulting in sulfide immiscibility and segregation; and （3） the timing of sulfide concentration in the intrusion. The super-large magmatic Ni-Cu sulfide deposits around the world have been found in small mafic-ultramafic intrusions, except for the Sudbury deposit. Studies in the past decade indicated that the intrusions hosting large and super-large magmatic sulfide deposits occur in magma conduits, such as those in China, including Jinchuan （Gansu）, Yangliuping （Sichuan）, Kalatongke （Xinjiang）, and Hongqiling （Jilin）. Magma conduits as open magma systems provide a perfect environment for extensive concentration of immiscible sulfide melts, which have been found to occur along deep regional faults. The origin of many mantle-derived magmas is closely associated with mantle plumes, intracontinental rifts, or post-collisional extension. Although it has been confirmed that sulfide immiscibility results from crustal contamination, grades of sulfide ores are also related to the nature of the parental magmas, the ratio between silicate magma and immiscible sulfide melt, the reaction between the sulfide melts and newly injected silicate magmas, and fractionation of the sulfide melt. The field relationships of the ore-bearing intrusion and the sulfide ore body are controlled by the geological features of the wall rocks. In this paper, we attempt to demonstrate the general characteristics, formation mechanism,tectonic settings, and indicators of magmatic sulfide deposits occurring in magmatic conduits which would provide guidelines for further exploration.
基金supported by the General Directorate of Mineral Research and Exploration。
文摘Pancarli Ni-Cu±(PGE)sulfide deposit occurs in the Neoproterozoic basement complex of the Bitlis massif,which is one of the Andean-type active continental margin fragments with arc-type assemblages represented by the Cadomian orogenic belt.Pancarli sulfides are associated with quartzo-feldspathic gneisses(country rock)and mafic intrusions(host rock).Composed of only semi-massive ore,the Ni-Cu±(PGE)sulfide deposit is a small-scale deposit,and it does not contain net-textured and disseminated ore.The mineral assemblage comprises pyrrhotite,pentlandite,and chalcopyrite.The semi-massive ore samples contain 2.2 wt.%-2.9 wt.%Ni,0.8 wt.%-2.2 wt.%Cu(Cu/(Cu+Ni)=0.2-0.5)and 0.13 wt.%-0.17 wt.%Co.The Cu/Ni ratios(average 0.57)are consistent with the segregation of sulfides from a basaltic magma.Low Pt+Pd100%S values of 0.08 ppm-0.89 ppm,relatively low Pt/Pd ratios of 0.2-1.4,and Pd/Ir ratios of 4.5-39 have also been revealed.These values demonstrate that the magma reached S saturation before its emplacement and the mineralization with high Cu/Pd ratios formed by sulfides segregated from a PGE-depleted magma.δ^34S isotope values(average-3.1‰)of Pancarli sulfides are lower than mantle source.Negativeδ^34S value indicates contamination from surrounding rocks.Concerning the composition,remobilization style and magma type,the Pancarli Ni-Cu±(PGE)sulfide deposit is similar to the deposits associated with Andean-type magmatic arcs located in the convergent plate margin settings.
