Dongguashan deposit is a large porphyry-skarn copper（gold） deposit in Tongling ore district. The Qingshanjiao intermediate acid intrusion of Yanshanian had a direct genetic relationship with mineralization. The magm...Dongguashan deposit is a large porphyry-skarn copper（gold） deposit in Tongling ore district. The Qingshanjiao intermediate acid intrusion of Yanshanian had a direct genetic relationship with mineralization. The magma origin, rock-forming dynamic background and rock-forming process were studied, and the rock-forming mechanism of Qingshanjiao intrusion was discussed, based on geological characteristics, detailed observation of petrography and systematic investigation of petrochemistry, trace elements and REE geochemistry characteristics of Qingshanjiao intrusion. The results show that Qingshanjiao rock body belongs to high-K calc-alkaline series with higher LREE elements, Th, Rb and Sr abundance, but depleted in HREE elements, Ba, Nb and Ta. The primary magma originated from the mantle-crust mixtures which were caused by basaltic magma of mantle mixing with syenite magma of partial melting of the lower crust, and the formation environment of Qingshanjiao intrusion was emplaced in the transitional environment from compression to extension. The Harker diagram and hybrid structures of plagioclase and potassium feldspar indicate that the fractional crystallization occurred in the process of magmatic evolution. The petrochemistry, trace elements and REE geochemistry characteristics indicate that the magma was contaminated by crustal material during the rock-forming. These results suggested that the Qingshanjiao intrusion was formed by fractional crystallization and assimilation and hybridization of mantle-crust magma in the transitional environment from compression to extensional.展开更多
REE and other trace elements in the altered marbles, massive skarns and ores, as well as garnet and quartz were determined in order to examine the behaviors of trace elements during hydrothermal alteration. It is demo...REE and other trace elements in the altered marbles, massive skarns and ores, as well as garnet and quartz were determined in order to examine the behaviors of trace elements during hydrothermal alteration. It is demonstrated that the high-field-strength (HFS) elements Zr, Hf, Th and Nb were immobile while other trace elements were mobile during the formation of skarns and related deposits. REE and ore-forming elements such as Cu and Ag in hydrothermally-altered marbles and skarns were provided primarily by hydrothermal fluids. In the direction transverse of the strata, the more deeply the marbles were altered, the higher the total REE abundance and the larger the negative Eu anomalies would be. The chondrite-normalized REE patterns of skarns are similar to those of the marbles, but the former are distinguished by much higher REE contents and more remarkable negative Eu anomalies. Those patterns were apparently not inherited from the marble protolith, but were controlled by garnets, which were determined by the hydrothermal solutions involved in the infiltration metasomatism. The hydrothermal fluids are characterized by having slightly right-hand dipping REE patterns, being enriched in LREE and having strongly negative Eu anomalies. The uptake of REE from hydrothermal fluids during the growth of garnet crystals resulted in the garnets having similar REE patterns to the hydrothermal fluids. Based on the spatial variation of REE in skarns and the structures of the hosting strata, we can get a better understanding of the transport path and pattern of the fluids involved in the formation of skarns and their related deposits. REE geochemistry investigation can help elucidate the genesis of skarns and skarn-related deposits.展开更多
Series of sedimentary hydrothermal-diplogenetic copper deposits have been found scattering in the region along the middle-lower reaches of the Yangtze River, and their metallogenetic mechanism is still in hot debate. ...Series of sedimentary hydrothermal-diplogenetic copper deposits have been found scattering in the region along the middle-lower reaches of the Yangtze River, and their metallogenetic mechanism is still in hot debate. In order to reveal the ore-forming kinetics of sedimentary process and hydrothermal superimposition, and evaluate the role of sedimentary pyrite in the enrichment and precipitation of copper, a set of simulating experiments on the reaction between pyrite and CuCl2 solution were conducted. According to the physicochemical characteristics of the ore-forming fluid of the Dongguashan copper deposit, Anhui Province, 100 MPa was selected as the experimental pressure, and the experimental temperatures were set at 450, 350, 250 and 150°C, respectively. The reactions between pyrite grains isolated from the Shimenkou strata-bound pyrite deposit and the solution with 0.2 mol/L CuCl2 and 1.0 mol/L NaCl were experimentally simulated. Then, variations in surface topography and surface chemistry of the experimental pyrite grains were documented using scanning electronic microscopy (SEM), atomic force microscopy (AFM), Auger electron spectrometry (AES) and X-ray photoelectron spectroscopy (XPS), and the solution and newly formed minerals were analyzed using inductively coupled plasma (ICP-AES) and X-ray diffraction (XRD) techniques. Desulphurization of pyrite surface was observed and new copper minerals were detected. It is proposed that pyrite can act as a geochemical barrier for the enrichment and precipitation of copper from the solution under the experimental conditions. Furthermore, the ore-forming mechanism of sedimentary hydrothermal-diplogenetic copper deposits was discussed.展开更多
The Bangong Lake-Nujiang River metallogenic belt is located between the Qiangtang Block and Lhasa Block, and the Duolong ore concentration area is located in the western section of the Bangong Lake-Nujiang River metal...The Bangong Lake-Nujiang River metallogenic belt is located between the Qiangtang Block and Lhasa Block, and the Duolong ore concentration area is located in the western section of the Bangong Lake-Nujiang River metallogenic belt. Till now, several large and super large copper-gold deposits, such as Duobuza, Bolong, Dibaonamugang, Naruo and Rongna deposits have been discovered in this area, mainly porphyry copper-gold ones.展开更多
基金Project(20091100704)supported by the Special Funds for Scientific Research of Land and Natural Resources,ChinaProject(2015CX008)supported by the Innovation Driven Plan of Central South University,China
文摘Dongguashan deposit is a large porphyry-skarn copper（gold） deposit in Tongling ore district. The Qingshanjiao intermediate acid intrusion of Yanshanian had a direct genetic relationship with mineralization. The magma origin, rock-forming dynamic background and rock-forming process were studied, and the rock-forming mechanism of Qingshanjiao intrusion was discussed, based on geological characteristics, detailed observation of petrography and systematic investigation of petrochemistry, trace elements and REE geochemistry characteristics of Qingshanjiao intrusion. The results show that Qingshanjiao rock body belongs to high-K calc-alkaline series with higher LREE elements, Th, Rb and Sr abundance, but depleted in HREE elements, Ba, Nb and Ta. The primary magma originated from the mantle-crust mixtures which were caused by basaltic magma of mantle mixing with syenite magma of partial melting of the lower crust, and the formation environment of Qingshanjiao intrusion was emplaced in the transitional environment from compression to extension. The Harker diagram and hybrid structures of plagioclase and potassium feldspar indicate that the fractional crystallization occurred in the process of magmatic evolution. The petrochemistry, trace elements and REE geochemistry characteristics indicate that the magma was contaminated by crustal material during the rock-forming. These results suggested that the Qingshanjiao intrusion was formed by fractional crystallization and assimilation and hybridization of mantle-crust magma in the transitional environment from compression to extensional.
基金supported by the National Natural Science Foundation of China(Grant Nos:49625304 and 49633120)the Ministry of Land and Resources of China(Grant No.2000401)the Ministry of Science and Technology of China through a National Climbing Project 95-P-39.
文摘REE and other trace elements in the altered marbles, massive skarns and ores, as well as garnet and quartz were determined in order to examine the behaviors of trace elements during hydrothermal alteration. It is demonstrated that the high-field-strength (HFS) elements Zr, Hf, Th and Nb were immobile while other trace elements were mobile during the formation of skarns and related deposits. REE and ore-forming elements such as Cu and Ag in hydrothermally-altered marbles and skarns were provided primarily by hydrothermal fluids. In the direction transverse of the strata, the more deeply the marbles were altered, the higher the total REE abundance and the larger the negative Eu anomalies would be. The chondrite-normalized REE patterns of skarns are similar to those of the marbles, but the former are distinguished by much higher REE contents and more remarkable negative Eu anomalies. Those patterns were apparently not inherited from the marble protolith, but were controlled by garnets, which were determined by the hydrothermal solutions involved in the infiltration metasomatism. The hydrothermal fluids are characterized by having slightly right-hand dipping REE patterns, being enriched in LREE and having strongly negative Eu anomalies. The uptake of REE from hydrothermal fluids during the growth of garnet crystals resulted in the garnets having similar REE patterns to the hydrothermal fluids. Based on the spatial variation of REE in skarns and the structures of the hosting strata, we can get a better understanding of the transport path and pattern of the fluids involved in the formation of skarns and their related deposits. REE geochemistry investigation can help elucidate the genesis of skarns and skarn-related deposits.
基金This work is supported by the National Natural Science Foundation of China （No. 49873016）；the Ph. D Program Foundation of Education of China （Nos. 20020284035, 20050284043）.
文摘Series of sedimentary hydrothermal-diplogenetic copper deposits have been found scattering in the region along the middle-lower reaches of the Yangtze River, and their metallogenetic mechanism is still in hot debate. In order to reveal the ore-forming kinetics of sedimentary process and hydrothermal superimposition, and evaluate the role of sedimentary pyrite in the enrichment and precipitation of copper, a set of simulating experiments on the reaction between pyrite and CuCl2 solution were conducted. According to the physicochemical characteristics of the ore-forming fluid of the Dongguashan copper deposit, Anhui Province, 100 MPa was selected as the experimental pressure, and the experimental temperatures were set at 450, 350, 250 and 150°C, respectively. The reactions between pyrite grains isolated from the Shimenkou strata-bound pyrite deposit and the solution with 0.2 mol/L CuCl2 and 1.0 mol/L NaCl were experimentally simulated. Then, variations in surface topography and surface chemistry of the experimental pyrite grains were documented using scanning electronic microscopy (SEM), atomic force microscopy (AFM), Auger electron spectrometry (AES) and X-ray photoelectron spectroscopy (XPS), and the solution and newly formed minerals were analyzed using inductively coupled plasma (ICP-AES) and X-ray diffraction (XRD) techniques. Desulphurization of pyrite surface was observed and new copper minerals were detected. It is proposed that pyrite can act as a geochemical barrier for the enrichment and precipitation of copper from the solution under the experimental conditions. Furthermore, the ore-forming mechanism of sedimentary hydrothermal-diplogenetic copper deposits was discussed.
基金granted by the Geological Survey Program of China Geological Survey (Grant No.1212011086074 and 12120113036500)
文摘The Bangong Lake-Nujiang River metallogenic belt is located between the Qiangtang Block and Lhasa Block, and the Duolong ore concentration area is located in the western section of the Bangong Lake-Nujiang River metallogenic belt. Till now, several large and super large copper-gold deposits, such as Duobuza, Bolong, Dibaonamugang, Naruo and Rongna deposits have been discovered in this area, mainly porphyry copper-gold ones.
