The Bulong gold deposit, located in the southwest Tianshan in China, occurs in the Upper Devonian finegrained clastic rocks. The gold orebodies are controlled by an gently inclined interlayer fractured zone. They are ...The Bulong gold deposit, located in the southwest Tianshan in China, occurs in the Upper Devonian finegrained clastic rocks. The gold orebodies are controlled by an gently inclined interlayer fractured zone. They are hosted only in quartz-barite veins though there are barite veins and quartz veins in the ore district. The δ34S values of pyrite in the ores range from 14.6‰ to 19.2‰ and those of barite from 35.0‰ to 39.6‰, indicating that the sulfur was derived from the strata. 3He/4He ratios of fluid inclusions in pyrite are 0.24-0.82 R/Ra, approximating to that of the crust. The 40Ar/39Ar ratios range from 338 to 471, slightly higher than that of the atmosphere. 40Ar /4He ratios of ore fluids range from 0.015 to 0.412 with a mean of 0.153. Helium and argon isotope compositions of fluid inclusions show that the ore fluids of the Bulong gold deposit were mainly derived from the crust.展开更多
The Yangshan gold deposit is a super-large fine-grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U-Pb ...The Yangshan gold deposit is a super-large fine-grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U-Pb dating techniques. It is found that zircons from quartz veinlet of the fine-grained disseminated gold ore show characters of magmatic origin with prism idiomorphism, oscillatory zoning and dominant Th/U ratios of 0.5-1.5. Three main populations of zircons are obtained, giving average 206Pb/238U ages of 197.6±1.7 Ma, 126.9±3.2 Ma and 51.2±1.3 Ma respectively. The first age corresponds to the K-Ar age of the plagiogranite dike, while the latter two ages indicate that buried Cretaceous and Tertiary intrusives exist in the orefield, suggesting that the Yangshan gold deposit was genetically related to the three magmatic hydrothermal activities. By contrast, zircons from coarse gold-bearing quartz vein in the mining area are much older than the host rock, indicating that the vein was formed earlier and was not contaminated by later magmatic fluids. It is concluded that the coupling of multiperiodic hydrothermal activities in the mining area has contributed a lot to mineralization of the Yangshan gold deposit.展开更多
The Rushan gold deposit, explored in recent years in the Jiaodong area, Shandong Province is a quartz vein-type gold deposit hosted in granite. The temperature of its major mineralization episode is between 220℃ and ...The Rushan gold deposit, explored in recent years in the Jiaodong area, Shandong Province is a quartz vein-type gold deposit hosted in granite. The temperature of its major mineralization episode is between 220℃ and 280℃. The salinity of the ore-forming fluid is 5 % to 9% NaCl equivalent, with H2O and CO2 as the dominant gas constituents. The fluid is rich in Na+, Ca+ and Cl-, but relatively impoverished in K+ and F-, characterized by either Ca2+ >Na+ >K+ (in three samples) or Na+ > Ca2+ > K+ (in six samples). Hydrogen and oxygen isotopes in the ore-forming fluid are highly variable with δ18 OH2O ranging between -7. 70‰ and 5. 97‰ and δDH2O between - 128‰ and - 71‰. The possibility of lamprophyre serving as the source of gold can be excluded in view of its low gold content on the order of 2. 5 × 10 -9. Rb-Sr isochron ages of the deposit and the host Kunyushan granite are (104. 8±1. 5) Ma and 134. 6 Ma respectively with the respective initial Sr ratios of 0. 71307 and 0. 7096. It is considered that the emplacement of the lamprophyre under a tensile environment had provided sufficient heat energy to facilitate deep circulation of meteoric water by which ore metals were extracted from the Kunyushan granite through long-term water-rock reaction.展开更多
The Qixia gold deposit is one of the important quartz vein-type deposits hosted inmetamorphic rocks in the east of Shandong, China. Compositionally the wolframite which isassociated with gold mineralization in the dep...The Qixia gold deposit is one of the important quartz vein-type deposits hosted inmetamorphic rocks in the east of Shandong, China. Compositionally the wolframite which isassociated with gold mineralization in the deposit is rich in iron, but poor in manganese, showing that this mineral crystallized from hydrothermal solution at low temperature. The temperatures at the main metallogenic stage of the Qixia gold deposit are Within the range of 160 -270t. The gaseous phases in fluid inclusions are dominated by H2O and CO2, while Na+,Ca2+ and Cl- are the major species in the fluid phase with K+ and F- present in relativelysmall amounts. The salinities of fluids are 4. 2 wt% - 8. 0 wt% NaCl equiv. Meanwhile, thefluid is characterized by either Ca2+ > Na+ > K+ (in five samples) or Na+ > Ca2 + > K+ (in twosamples), quite similar to the composition of ore-forming fluid derived from meteoric water.Primary data on the hydrogen and oxygen isotopic compositions of the ore-forming fluid fallwithin a wide range: δ%H2o = - 56‰-95‰ and δ18OH2O=- 3.6‰-4. 5‰ relative toSMOW. These isotopic values fully reflect the distribution features of meteoric water which hasexchanged with the metamorphic rocks of the Jiaodong Group at different temperatures and W/R ratios, and the metallogenic process is characterized by low W/R ratios. The Rb-Sr isochronage of the Qixia gold deposit is 125. 8 ± 1. 7 Ma, with (87Sr/86Sr) being 0. 7168, and the timeinterval between the gold deposit and its country rocks (granite or metamoprhic rocks) is verylarge. The formation Of the Qiaxia gold deposit is directly related to the evolution of geologicalhistory in eastern Shandong, and a genetic model in which the deep convective circulating meteoric water reacts with the country rocks can be used to explain the metallogenic mechanism ofthe deposit.展开更多
Metallogenic models of gold deposits of quartz vein type and altered rock type will be dis-cussed in this note. They are considered to be closely related to granite spatially andgenetically.
基金the Ministry of Science and Technology of China(grants G 2001CB 409807,G 1999043216).
文摘The Bulong gold deposit, located in the southwest Tianshan in China, occurs in the Upper Devonian finegrained clastic rocks. The gold orebodies are controlled by an gently inclined interlayer fractured zone. They are hosted only in quartz-barite veins though there are barite veins and quartz veins in the ore district. The δ34S values of pyrite in the ores range from 14.6‰ to 19.2‰ and those of barite from 35.0‰ to 39.6‰, indicating that the sulfur was derived from the strata. 3He/4He ratios of fluid inclusions in pyrite are 0.24-0.82 R/Ra, approximating to that of the crust. The 40Ar/39Ar ratios range from 338 to 471, slightly higher than that of the atmosphere. 40Ar /4He ratios of ore fluids range from 0.015 to 0.412 with a mean of 0.153. Helium and argon isotope compositions of fluid inclusions show that the ore fluids of the Bulong gold deposit were mainly derived from the crust.
文摘The Yangshan gold deposit is a super-large fine-grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U-Pb dating techniques. It is found that zircons from quartz veinlet of the fine-grained disseminated gold ore show characters of magmatic origin with prism idiomorphism, oscillatory zoning and dominant Th/U ratios of 0.5-1.5. Three main populations of zircons are obtained, giving average 206Pb/238U ages of 197.6±1.7 Ma, 126.9±3.2 Ma and 51.2±1.3 Ma respectively. The first age corresponds to the K-Ar age of the plagiogranite dike, while the latter two ages indicate that buried Cretaceous and Tertiary intrusives exist in the orefield, suggesting that the Yangshan gold deposit was genetically related to the three magmatic hydrothermal activities. By contrast, zircons from coarse gold-bearing quartz vein in the mining area are much older than the host rock, indicating that the vein was formed earlier and was not contaminated by later magmatic fluids. It is concluded that the coupling of multiperiodic hydrothermal activities in the mining area has contributed a lot to mineralization of the Yangshan gold deposit.
文摘The Rushan gold deposit, explored in recent years in the Jiaodong area, Shandong Province is a quartz vein-type gold deposit hosted in granite. The temperature of its major mineralization episode is between 220℃ and 280℃. The salinity of the ore-forming fluid is 5 % to 9% NaCl equivalent, with H2O and CO2 as the dominant gas constituents. The fluid is rich in Na+, Ca+ and Cl-, but relatively impoverished in K+ and F-, characterized by either Ca2+ >Na+ >K+ (in three samples) or Na+ > Ca2+ > K+ (in six samples). Hydrogen and oxygen isotopes in the ore-forming fluid are highly variable with δ18 OH2O ranging between -7. 70‰ and 5. 97‰ and δDH2O between - 128‰ and - 71‰. The possibility of lamprophyre serving as the source of gold can be excluded in view of its low gold content on the order of 2. 5 × 10 -9. Rb-Sr isochron ages of the deposit and the host Kunyushan granite are (104. 8±1. 5) Ma and 134. 6 Ma respectively with the respective initial Sr ratios of 0. 71307 and 0. 7096. It is considered that the emplacement of the lamprophyre under a tensile environment had provided sufficient heat energy to facilitate deep circulation of meteoric water by which ore metals were extracted from the Kunyushan granite through long-term water-rock reaction.
文摘The Qixia gold deposit is one of the important quartz vein-type deposits hosted inmetamorphic rocks in the east of Shandong, China. Compositionally the wolframite which isassociated with gold mineralization in the deposit is rich in iron, but poor in manganese, showing that this mineral crystallized from hydrothermal solution at low temperature. The temperatures at the main metallogenic stage of the Qixia gold deposit are Within the range of 160 -270t. The gaseous phases in fluid inclusions are dominated by H2O and CO2, while Na+,Ca2+ and Cl- are the major species in the fluid phase with K+ and F- present in relativelysmall amounts. The salinities of fluids are 4. 2 wt% - 8. 0 wt% NaCl equiv. Meanwhile, thefluid is characterized by either Ca2+ > Na+ > K+ (in five samples) or Na+ > Ca2 + > K+ (in twosamples), quite similar to the composition of ore-forming fluid derived from meteoric water.Primary data on the hydrogen and oxygen isotopic compositions of the ore-forming fluid fallwithin a wide range: δ%H2o = - 56‰-95‰ and δ18OH2O=- 3.6‰-4. 5‰ relative toSMOW. These isotopic values fully reflect the distribution features of meteoric water which hasexchanged with the metamorphic rocks of the Jiaodong Group at different temperatures and W/R ratios, and the metallogenic process is characterized by low W/R ratios. The Rb-Sr isochronage of the Qixia gold deposit is 125. 8 ± 1. 7 Ma, with (87Sr/86Sr) being 0. 7168, and the timeinterval between the gold deposit and its country rocks (granite or metamoprhic rocks) is verylarge. The formation Of the Qiaxia gold deposit is directly related to the evolution of geologicalhistory in eastern Shandong, and a genetic model in which the deep convective circulating meteoric water reacts with the country rocks can be used to explain the metallogenic mechanism ofthe deposit.
基金Project supported by Doctorate Foundation of the State Education Commission of China.
文摘Metallogenic models of gold deposits of quartz vein type and altered rock type will be dis-cussed in this note. They are considered to be closely related to granite spatially andgenetically.
