Fluid inclusions in the gold-bearing quartz veins at the Um Rus area are of three types: H\-2O, H\-2O-CO\-2 and CO\-2 inclusions. H\-2O inclusions are the most abundant, they include two phases which exhibit low and h...Fluid inclusions in the gold-bearing quartz veins at the Um Rus area are of three types: H\-2O, H\-2O-CO\-2 and CO\-2 inclusions. H\-2O inclusions are the most abundant, they include two phases which exhibit low and high homogenization temperatures ranging from 150 to 200℃ and 175 to 250℃, respectively. The salinity of aqueous inclusions, based on ice melting, varies between \{6.1\} and 8 equiv. wt% NaCl. On the other hand, H\-2O-CO\-2 fluid inclusions include three phases. Their total homogenization temperatures range from 270 to 325℃, and their salinity, based on clathrate melting, ranges between \{0.8\} and \{3.8\} equiv. wt% NaCl. CO\-2 fluid inclusions homogenize to a liquid phase and exhibit a low density range from \{0.52\} to \{0.66\} g/cm\+3. The partial mixing of H\-2O-CO\-2 and salt H\-2O-NaCl fluid inclusions is the main source of fluids from which the other types of inclusions were derived. The gold-bearing quartz veins are believed to be of medium temperature hydrothermal convective origin.展开更多
In the eastern part of China there had occurred large\|scale gold mineralization during the Mesozoic, resulting in a large number of important gold ore\|concentrated areas. In this paper we have selected some isotope ...In the eastern part of China there had occurred large\|scale gold mineralization during the Mesozoic, resulting in a large number of important gold ore\|concentrated areas. In this paper we have selected some isotope data (including four gold deposits previously studied and two gold deposits in this work) of Au\|bearing quartz veins of the representative gold deposits in six important gold ore\|concentrated areas in the periphery of the North China Platform and calculated their metallogenic ages using the method of Ludwig (2.90 version). The results show that the representative gold deposits in the six gold ore\|concentrated areas were formed during the Mesozoic.展开更多
Gold-bearing quartz veins of the Taihua Group consisting of Archean metavolcanic rocks are a main gold deposit type in the Xiao Qinling area,one of the three biggest gold production areas in China.The quartz veins exp...Gold-bearing quartz veins of the Taihua Group consisting of Archean metavolcanic rocks are a main gold deposit type in the Xiao Qinling area,one of the three biggest gold production areas in China.The quartz veins experienced strong alteration characterized by a typical mesothermal hydrothermal altered mineral assemblage.The grade of gold is affected by the contents of sulphides,e.g.galena,pyrite and chalcopyrite.Results of minor elements analysis for the of gold-bearing quartz veins indicate higher contents of Au and high contents of Ag,Pb,Cu,Cd,W,and Mo.Abundant fluid inclusions were found in the gold-bearing quartz veins.Three types of fluid inclusions were identified:(1) aqueous inclusions;(2) CO 2-bearing inclusions;and(3) daughter crystal-bearing fluid inclusions.Homogenization temperatures ranged from 110 to 670℃ with low and high peaks appearing at 160 180℃ and 280 300℃,respectively.The salinity of aqueous inclusions varies between 1.8 wt% and 38.2 wt% NaCl.The homogenization temperature and salinity show a positive correlation.The H and O isotopes of fluid inclusions in the gold-bearing quartz veins indicate that magmatic solution and metamorphic hydrothermal solution,together with meteoric water,were involved in the formation of gold-bearing fluid.Mesozoic magma activities related to granite intrusions should be the main source of CO 2 fluid with higher temperature and salinity.展开更多
Fluid inclusion research in Archean metamorphic rocks, Yanshanian granite and gold-bearing quartz veins shows that regional metamorphic fluids are high temperature and high saline, Yanshanian post-granitic fluids are ...Fluid inclusion research in Archean metamorphic rocks, Yanshanian granite and gold-bearing quartz veins shows that regional metamorphic fluids are high temperature and high saline, Yanshanian post-granitic fluids are CO2-bearing low saline, and ore-forming fluids are also CO2-rich low saline. In gold-barren/free parts of quartz veins in gold deposits, daughter mineral-bearing high saline inclusions related with metamorphic fluids remained. This proclaims quartz veins hosting gold ores might have been formed in early metamorphism, and overlapped or mineralized by late Yanshanian gold-bearing fluids.展开更多
The Linglong-Jiaojia district is one of the most important regions containing gold deposits in China. These gold deposits can be divided into: a) the pyrite-gold-quartz vein type (Linglong type), which is controlled b...The Linglong-Jiaojia district is one of the most important regions containing gold deposits in China. These gold deposits can be divided into: a) the pyrite-gold-quartz vein type (Linglong type), which is controlled by brittle-ductile to ductile deformation structures, and b) the alteration-zone type (Jiaojia type), characterized by small veinlets, or the disseminated type recognized in brittle shear zones. Lode gold deposits in the Jiaojia area occur in NE brittle fracture zones, formed in a dominantly simple shear deformation regime, mainly in thrust attitude with a minor sinistral strike slip component. In the Linglong area, the lode gold deposits are located at the intersection of three types of structures: NNE and NE brittle-ductile fault zones and the ENE ductile reverse shear zone in the south of the area. The structural characteristics of these brittle shear zones are consistent with a tectonic NNW-SSE principal stress field orientation. Similar stresses explain the ENE Qixia fold axes, the Potouqing and several other ENE reverse ductile shear zones elsewhere in the region, the Tancheng-Lujiang fault zone and its subsidiaries in the vicinity of the Linglong-Jiaojia district, as well as the southern ENE suture zone north of Qingdao. Therefore these structural systems occurred as part of different major tectonic events under NNW-SSE compression principal stress fields in the area. Gold deposits are hosted in smaller-scale structures within the brittle fault zones and brittle-ductile shear zones. Although ore bodies and, on a smaller scale, quartz ore veins often seem to be randomly oriented, it is possible to explain their distribution and orientation in terms of the simple shear deformation process under which they were developed. The progressive simple shear failure is characterized by various fracture modes (tension and shear) that intervene in sequence. The tension and shear fractures are influenced by the stress level (depth of burial beneath the paleosurface) in their structural behavior, show variable dilatancy (void openings) and extend on all scales. By making use of these characteristics, a progressive failure analysis can be applied to predicting the shape and extent of ore bodies as well as the styles of mineralization at any given location.展开更多
The Jinshan gold deposit consists of gold\|bearing ultramylonite and gold\|bearing quartz vein ores. The Rb\|Sr isochron age of fluid inclusions in quartz from quartz veins is the same as that of the gold\|bearing ult...The Jinshan gold deposit consists of gold\|bearing ultramylonite and gold\|bearing quartz vein ores. The Rb\|Sr isochron age of fluid inclusions in quartz from quartz veins is the same as that of the gold\|bearing ultramylonite, suggesting that both the types of orebodies were formed simultaneously in the Caledonian period, in the range 406-409 Ma. REE patterns and sulfur, lead, carbon, hydrogen and oxygen isotope data, as well as the composition of fluid inclusions, have shown that the ore\|forming fluids were derived from formation water, and the ore\|forming materials came from the gold\|hosted rocks. The Jinshan gold deposit occurring in a Caledonian brittle\|ductile zone in metamorphosed microclastic rocks owes its origin to Caledonian reworking processes.展开更多
文摘Fluid inclusions in the gold-bearing quartz veins at the Um Rus area are of three types: H\-2O, H\-2O-CO\-2 and CO\-2 inclusions. H\-2O inclusions are the most abundant, they include two phases which exhibit low and high homogenization temperatures ranging from 150 to 200℃ and 175 to 250℃, respectively. The salinity of aqueous inclusions, based on ice melting, varies between \{6.1\} and 8 equiv. wt% NaCl. On the other hand, H\-2O-CO\-2 fluid inclusions include three phases. Their total homogenization temperatures range from 270 to 325℃, and their salinity, based on clathrate melting, ranges between \{0.8\} and \{3.8\} equiv. wt% NaCl. CO\-2 fluid inclusions homogenize to a liquid phase and exhibit a low density range from \{0.52\} to \{0.66\} g/cm\+3. The partial mixing of H\-2O-CO\-2 and salt H\-2O-NaCl fluid inclusions is the main source of fluids from which the other types of inclusions were derived. The gold-bearing quartz veins are believed to be of medium temperature hydrothermal convective origin.
基金This research project was granted jointly by the State Key Program (95pre39)sponsored by the China National Science and Tech nology Departmentthe State Out standing Young Scientists Foundation (GrantNo .4 96 2 5 3 0 4 ) and the Open Lab.of Ore Depo
文摘In the eastern part of China there had occurred large\|scale gold mineralization during the Mesozoic, resulting in a large number of important gold ore\|concentrated areas. In this paper we have selected some isotope data (including four gold deposits previously studied and two gold deposits in this work) of Au\|bearing quartz veins of the representative gold deposits in six important gold ore\|concentrated areas in the periphery of the North China Platform and calculated their metallogenic ages using the method of Ludwig (2.90 version). The results show that the representative gold deposits in the six gold ore\|concentrated areas were formed during the Mesozoic.
基金supported jointly by the CNSF (No. 41173055)the National Basic Research Program of China (No.2003CB214605)
文摘Gold-bearing quartz veins of the Taihua Group consisting of Archean metavolcanic rocks are a main gold deposit type in the Xiao Qinling area,one of the three biggest gold production areas in China.The quartz veins experienced strong alteration characterized by a typical mesothermal hydrothermal altered mineral assemblage.The grade of gold is affected by the contents of sulphides,e.g.galena,pyrite and chalcopyrite.Results of minor elements analysis for the of gold-bearing quartz veins indicate higher contents of Au and high contents of Ag,Pb,Cu,Cd,W,and Mo.Abundant fluid inclusions were found in the gold-bearing quartz veins.Three types of fluid inclusions were identified:(1) aqueous inclusions;(2) CO 2-bearing inclusions;and(3) daughter crystal-bearing fluid inclusions.Homogenization temperatures ranged from 110 to 670℃ with low and high peaks appearing at 160 180℃ and 280 300℃,respectively.The salinity of aqueous inclusions varies between 1.8 wt% and 38.2 wt% NaCl.The homogenization temperature and salinity show a positive correlation.The H and O isotopes of fluid inclusions in the gold-bearing quartz veins indicate that magmatic solution and metamorphic hydrothermal solution,together with meteoric water,were involved in the formation of gold-bearing fluid.Mesozoic magma activities related to granite intrusions should be the main source of CO 2 fluid with higher temperature and salinity.
文摘Fluid inclusion research in Archean metamorphic rocks, Yanshanian granite and gold-bearing quartz veins shows that regional metamorphic fluids are high temperature and high saline, Yanshanian post-granitic fluids are CO2-bearing low saline, and ore-forming fluids are also CO2-rich low saline. In gold-barren/free parts of quartz veins in gold deposits, daughter mineral-bearing high saline inclusions related with metamorphic fluids remained. This proclaims quartz veins hosting gold ores might have been formed in early metamorphism, and overlapped or mineralized by late Yanshanian gold-bearing fluids.
基金This paper is a part of results from the project ＂Shear Zone Control Gold Deposits in China＂ supported by the National Natural Science Foundation of China and an international exchange project supported by the same institution （to Lu）.
文摘The Linglong-Jiaojia district is one of the most important regions containing gold deposits in China. These gold deposits can be divided into: a) the pyrite-gold-quartz vein type (Linglong type), which is controlled by brittle-ductile to ductile deformation structures, and b) the alteration-zone type (Jiaojia type), characterized by small veinlets, or the disseminated type recognized in brittle shear zones. Lode gold deposits in the Jiaojia area occur in NE brittle fracture zones, formed in a dominantly simple shear deformation regime, mainly in thrust attitude with a minor sinistral strike slip component. In the Linglong area, the lode gold deposits are located at the intersection of three types of structures: NNE and NE brittle-ductile fault zones and the ENE ductile reverse shear zone in the south of the area. The structural characteristics of these brittle shear zones are consistent with a tectonic NNW-SSE principal stress field orientation. Similar stresses explain the ENE Qixia fold axes, the Potouqing and several other ENE reverse ductile shear zones elsewhere in the region, the Tancheng-Lujiang fault zone and its subsidiaries in the vicinity of the Linglong-Jiaojia district, as well as the southern ENE suture zone north of Qingdao. Therefore these structural systems occurred as part of different major tectonic events under NNW-SSE compression principal stress fields in the area. Gold deposits are hosted in smaller-scale structures within the brittle fault zones and brittle-ductile shear zones. Although ore bodies and, on a smaller scale, quartz ore veins often seem to be randomly oriented, it is possible to explain their distribution and orientation in terms of the simple shear deformation process under which they were developed. The progressive simple shear failure is characterized by various fracture modes (tension and shear) that intervene in sequence. The tension and shear fractures are influenced by the stress level (depth of burial beneath the paleosurface) in their structural behavior, show variable dilatancy (void openings) and extend on all scales. By making use of these characteristics, a progressive failure analysis can be applied to predicting the shape and extent of ore bodies as well as the styles of mineralization at any given location.
文摘The Jinshan gold deposit consists of gold\|bearing ultramylonite and gold\|bearing quartz vein ores. The Rb\|Sr isochron age of fluid inclusions in quartz from quartz veins is the same as that of the gold\|bearing ultramylonite, suggesting that both the types of orebodies were formed simultaneously in the Caledonian period, in the range 406-409 Ma. REE patterns and sulfur, lead, carbon, hydrogen and oxygen isotope data, as well as the composition of fluid inclusions, have shown that the ore\|forming fluids were derived from formation water, and the ore\|forming materials came from the gold\|hosted rocks. The Jinshan gold deposit occurring in a Caledonian brittle\|ductile zone in metamorphosed microclastic rocks owes its origin to Caledonian reworking processes.
