Tongguanshan copper deposit of Tongling large ore belt is one of the typicalskarn copper deposits. Based on careful observation under microscope many daughter mineralsincluding transparent ones and opaque ones have be...Tongguanshan copper deposit of Tongling large ore belt is one of the typicalskarn copper deposits. Based on careful observation under microscope many daughter mineralsincluding transparent ones and opaque ones have been distinguished in the fluid inclusions of garnetand diopside. The results of SEM/EDS (scanning electron microscope/energy dispersive spectrometer)and LRM (laser Raman microprobe) analysis show that these daughter minerals in garnet are sylvite,halite, sphalerite, chalcopyrite and carbonate. Sylvite daughter mineral is very popular in garnetand diopside. The existence of so much sylvite daughter mineral and other daughter minerals in thefluid inclusions indicates that the ore--forming fluid is of supper-high salinity and high potassiumconcentration. High potassium concentration in the fluid inclusions agrees with K-richmesotype--acid rock and K-silicate alteration that occurred widely in this area. The daughtermineral assemblage in garnet and diopside is similar to the mineral assemblage of ore-forming stagethat followed skarn stage.展开更多
Trace elements including REE (Rare Earth Elements) in fluid inclusions inlherzolite, olivine, orthopyroxene, and clinopyroxene have been determined by heating-decrepitationand ICP-MS (Element Type Inductively Coupled ...Trace elements including REE (Rare Earth Elements) in fluid inclusions inlherzolite, olivine, orthopyroxene, and clinopyroxene have been determined by heating-decrepitationand ICP-MS (Element Type Inductively Coupled Plasma-Mass Spectrometry) method. Normalized CO_2fluid/chondrite data show that mantle fluids are rich in REEs, especially LREEs (Light Rare EarthElements), several times or dozen times higher than mantle rocks and mantle minerals. There areclose relationships among the REE data of olivine, orthopyroxene, clinopyroxene and lherzolite.Compared to the data of chemical dissolution method, it is believed that REE data obtained fromheating-decrepitation and ICP-MS technique are contributed by CO_2 fluid inclusions. About 60percent (mass fraction) of tiny inclusions are observed not to be decrepitated above 1000 deg C, soREE data obtained are only contributed by decrepitated inclusions. Mantle fluids rich in LREE playan important role in mantle metasomatism, partial melting and mineralization.展开更多
In minerals of mantle xenoliths captured within Tertiary alkali-basalt from Xinchang, Zhejiang province, China, many sulfidemelt inclusions were found by the observation of polished thin section. Electron microprobe ...In minerals of mantle xenoliths captured within Tertiary alkali-basalt from Xinchang, Zhejiang province, China, many sulfidemelt inclusions were found by the observation of polished thin section. Electron microprobe analysis has been applied to detect the components of sulfide-melt inclusions. The result shows that the sulfide phases of inclusions are mainly pentlandite, and secondarily pyrrho- tite, The molar ratio of Ni to Fe, r_Ni,/r_Fe, of mineral phases in sulfide inclusions is related to olivine contents in host mantle xenoliths. The r_Ni/r_Ni, of sulfides from Xinchang samples has a possitive correlation to r_(Fe+Ni),/r_S. The r_(Fe+Ni),/r_S, becomes higher with the increasing of r_Ni/r_Fe In single sulfide-melt inclusions, r_Ni,/r_Fe, r_(Fe+Ni),/r, and Ni contents increase from the center to edge, reflecting a result of different cooling speed in an inclusion. A comparison between the data from Hannuoba, West Eifel of Germany and Nograd-Gomor of east Europe suggests that the composition of the inclusions is different for each area, which indicated that a regional differentiation of sulfide in mantle fluids.展开更多
Granulite xenoliths are important samples for understanding the forming and evolution of the crust. The granulite xeno- liths enclosed in Cenozoic basalt of Hannuoba, Hebei Province, China, contain four types of sulf...Granulite xenoliths are important samples for understanding the forming and evolution of the crust. The granulite xeno- liths enclosed in Cenozoic basalt of Hannuoba, Hebei Province, China, contain four types of sulfide assemblages: isolate rotundity enclosed sulfides, intergranular sulfides between minerals, secondary sulfide inclusions ranging in linear, and fissure-filling sulfides. Electron microprobe analysis shows that the components of sulfides are Ni-poor pyrrhotite with the molar ratios of (Ni+Co+Cu)/Fe less than 0.2. The molar ratios of (Fe+Cu+Co+Ni)/S are less than 0.875 of normal pyrrhotite, and are less than those of mantle xeno- liths, reflecting a sulfur-saturated environment. Pyrrhotite in various occurrences contains some Au and Ag, with the averages of 0.19wt%-0.22wt% Au and 0.01wt%-0.02wt% Ag, showing the gold mineralization related to the granulitization of low crust. Ni, Co and Cu have a normal correlation with S in pyrrhotite, indicating that heavy metal elements have a same source similar to sulfur be- cause of the degasification of upper mantle.展开更多
文摘Tongguanshan copper deposit of Tongling large ore belt is one of the typicalskarn copper deposits. Based on careful observation under microscope many daughter mineralsincluding transparent ones and opaque ones have been distinguished in the fluid inclusions of garnetand diopside. The results of SEM/EDS (scanning electron microscope/energy dispersive spectrometer)and LRM (laser Raman microprobe) analysis show that these daughter minerals in garnet are sylvite,halite, sphalerite, chalcopyrite and carbonate. Sylvite daughter mineral is very popular in garnetand diopside. The existence of so much sylvite daughter mineral and other daughter minerals in thefluid inclusions indicates that the ore--forming fluid is of supper-high salinity and high potassiumconcentration. High potassium concentration in the fluid inclusions agrees with K-richmesotype--acid rock and K-silicate alteration that occurred widely in this area. The daughtermineral assemblage in garnet and diopside is similar to the mineral assemblage of ore-forming stagethat followed skarn stage.
基金The work was financial support by National Natural Science Foundation of China (No.49972031).]
文摘Trace elements including REE (Rare Earth Elements) in fluid inclusions inlherzolite, olivine, orthopyroxene, and clinopyroxene have been determined by heating-decrepitationand ICP-MS (Element Type Inductively Coupled Plasma-Mass Spectrometry) method. Normalized CO_2fluid/chondrite data show that mantle fluids are rich in REEs, especially LREEs (Light Rare EarthElements), several times or dozen times higher than mantle rocks and mantle minerals. There areclose relationships among the REE data of olivine, orthopyroxene, clinopyroxene and lherzolite.Compared to the data of chemical dissolution method, it is believed that REE data obtained fromheating-decrepitation and ICP-MS technique are contributed by CO_2 fluid inclusions. About 60percent (mass fraction) of tiny inclusions are observed not to be decrepitated above 1000 deg C, soREE data obtained are only contributed by decrepitated inclusions. Mantle fluids rich in LREE playan important role in mantle metasomatism, partial melting and mineralization.
文摘In minerals of mantle xenoliths captured within Tertiary alkali-basalt from Xinchang, Zhejiang province, China, many sulfidemelt inclusions were found by the observation of polished thin section. Electron microprobe analysis has been applied to detect the components of sulfide-melt inclusions. The result shows that the sulfide phases of inclusions are mainly pentlandite, and secondarily pyrrho- tite, The molar ratio of Ni to Fe, r_Ni,/r_Fe, of mineral phases in sulfide inclusions is related to olivine contents in host mantle xenoliths. The r_Ni/r_Ni, of sulfides from Xinchang samples has a possitive correlation to r_(Fe+Ni),/r_S. The r_(Fe+Ni),/r_S, becomes higher with the increasing of r_Ni/r_Fe In single sulfide-melt inclusions, r_Ni,/r_Fe, r_(Fe+Ni),/r, and Ni contents increase from the center to edge, reflecting a result of different cooling speed in an inclusion. A comparison between the data from Hannuoba, West Eifel of Germany and Nograd-Gomor of east Europe suggests that the composition of the inclusions is different for each area, which indicated that a regional differentiation of sulfide in mantle fluids.
基金This study was financially supported by the National Natural Science Foundation of China (No.49972031) and the Key Laboratory of Mineral Resources of the Institute of Geology and Geophysics Chinese Academy of Sciences.
文摘Granulite xenoliths are important samples for understanding the forming and evolution of the crust. The granulite xeno- liths enclosed in Cenozoic basalt of Hannuoba, Hebei Province, China, contain four types of sulfide assemblages: isolate rotundity enclosed sulfides, intergranular sulfides between minerals, secondary sulfide inclusions ranging in linear, and fissure-filling sulfides. Electron microprobe analysis shows that the components of sulfides are Ni-poor pyrrhotite with the molar ratios of (Ni+Co+Cu)/Fe less than 0.2. The molar ratios of (Fe+Cu+Co+Ni)/S are less than 0.875 of normal pyrrhotite, and are less than those of mantle xeno- liths, reflecting a sulfur-saturated environment. Pyrrhotite in various occurrences contains some Au and Ag, with the averages of 0.19wt%-0.22wt% Au and 0.01wt%-0.02wt% Ag, showing the gold mineralization related to the granulitization of low crust. Ni, Co and Cu have a normal correlation with S in pyrrhotite, indicating that heavy metal elements have a same source similar to sulfur be- cause of the degasification of upper mantle.
