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
The Shuiyindong deposit is one of the largest (more than 100 tonnes of Au) and highest grade (more than 7×10-6-10×10-6), strata-bound Carlintype gold deposits in southwestern Guizhou Province, China. The dep...The Shuiyindong deposit is one of the largest (more than 100 tonnes of Au) and highest grade (more than 7×10-6-10×10-6), strata-bound Carlintype gold deposits in southwestern Guizhou Province, China. The deposit is controlled by both structure and favorable lithology. It is situated near the axis of the striking Huijiabao anticline and is hosted in bioclastic limestone of the Permian Longtan Formation. Gold mineralization occurred under low temperature with Th of 220℃± and is closely associated with decarbonation, silicification, sulfidation and dolomitization. The deposit has a characteristic elemental assemblage of Au-As-Hg-Tl. Studies of geochemistry and isotope compositions indicated that the ore-bearing materials and fluids of the gold deposit mainly originated from a plutonic source, and possess a mixing feature with the strata matter during transportation from mantle to crust. Fluid inclusions in vein quartz from the gold deposit are rich in volatile flux, indicating that metallogenic fluid is an overpres-sured one. The activity and geothermal state of the Earth's crust in the long period of time are favorable for the formation of overpressured fluids in a large area, and extensive structures would drive the fluids into ore-forming sys-tem and make gold deposits formed. The complexity of structural movement in the upper crust of southwestern Guizhou Province resulted in complicated gold mineralization. Through metallogenic prognosis and exploration, the proven reserves of the deposit increased by tens of tonnes of Au and the deposit has become a super-large strata-bound Carlin-type gold deposit.展开更多
Based on detailed geologic study, the important role of structuring in the formation of gold deposits in the area is discussed with special reference to structural evolution. Syngenetic faulting contemporaneous with t...Based on detailed geologic study, the important role of structuring in the formation of gold deposits in the area is discussed with special reference to structural evolution. Syngenetic faulting contemporaneous with tectonic-volcanic events is thought to be responsible for providing the ore-forming material at depth. The lithofacies formed by highly alternating deposition of terrestrial and carbonate detritus is chemically characterized by the assemblage of Au-Sb-As,constituting a favorable source bed for the activation and enrichment of gold. This gold source bed has undergone four major stages of structural deformation, accompanied by multi-staged alteration and mineralization.展开更多
This study focuses on the close association between Devonian reefs and the strata-bound ore deposits in South China.For the first time,the development of Devonian reefs was subdivided into three stages,respectively as...This study focuses on the close association between Devonian reefs and the strata-bound ore deposits in South China.For the first time,the development of Devonian reefs was subdivided into three stages,respectively as the initial,succeeding and peak stages,and its evolution model is proposed.In Dachang,Nandan county,Guangxi Zhuang Autonomous Region(Guangxi for short),a large-scale strata-bound ore deposit formed in a Devonian reef,which was affected by marine volcanic activities and Mesozoic magmatic intrusions.The reef-building reached its peak stage at the Givetian,indicating a large-scale build-up of reef and inter-reef depression.In central-eastern Hunan Province,the strata-bound ore deposits belong to low-temperature ore-types without later magmatic intrusions or volcanic activities.In Hunan Province as well as many other localities in South China,the Givetian reefs played important roles in mobilizing ore-forming materials from the surrounding pre-Devonian rocks,providing spaces and passages for transporting hydrothermal fluid,and progressing mineralization and accumulation of ore-forming materials.展开更多
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supported jointly by the State Science and Technology Supporting Program (2006BAB01A13)the self-research project funded by the State Key Laboratory of Ore Deposit Geochemistry (Ore Deposit Special Research Project 2008.3-2)Guizhou Provincial Bureau of Geology and Mineral Resource Exploration and Development [Qian Di Kuang Ke (2009) No. 11]
文摘The Shuiyindong deposit is one of the largest (more than 100 tonnes of Au) and highest grade (more than 7×10-6-10×10-6), strata-bound Carlintype gold deposits in southwestern Guizhou Province, China. The deposit is controlled by both structure and favorable lithology. It is situated near the axis of the striking Huijiabao anticline and is hosted in bioclastic limestone of the Permian Longtan Formation. Gold mineralization occurred under low temperature with Th of 220℃± and is closely associated with decarbonation, silicification, sulfidation and dolomitization. The deposit has a characteristic elemental assemblage of Au-As-Hg-Tl. Studies of geochemistry and isotope compositions indicated that the ore-bearing materials and fluids of the gold deposit mainly originated from a plutonic source, and possess a mixing feature with the strata matter during transportation from mantle to crust. Fluid inclusions in vein quartz from the gold deposit are rich in volatile flux, indicating that metallogenic fluid is an overpres-sured one. The activity and geothermal state of the Earth's crust in the long period of time are favorable for the formation of overpressured fluids in a large area, and extensive structures would drive the fluids into ore-forming sys-tem and make gold deposits formed. The complexity of structural movement in the upper crust of southwestern Guizhou Province resulted in complicated gold mineralization. Through metallogenic prognosis and exploration, the proven reserves of the deposit increased by tens of tonnes of Au and the deposit has become a super-large strata-bound Carlin-type gold deposit.
文摘Based on detailed geologic study, the important role of structuring in the formation of gold deposits in the area is discussed with special reference to structural evolution. Syngenetic faulting contemporaneous with tectonic-volcanic events is thought to be responsible for providing the ore-forming material at depth. The lithofacies formed by highly alternating deposition of terrestrial and carbonate detritus is chemically characterized by the assemblage of Au-Sb-As,constituting a favorable source bed for the activation and enrichment of gold. This gold source bed has undergone four major stages of structural deformation, accompanied by multi-staged alteration and mineralization.
基金the Chinese Academy of Sciences(Grant No.XDB26000000)the Natural Science Foundation of Jiangsu Province(Grant No.BK20171102)。
文摘This study focuses on the close association between Devonian reefs and the strata-bound ore deposits in South China.For the first time,the development of Devonian reefs was subdivided into three stages,respectively as the initial,succeeding and peak stages,and its evolution model is proposed.In Dachang,Nandan county,Guangxi Zhuang Autonomous Region(Guangxi for short),a large-scale strata-bound ore deposit formed in a Devonian reef,which was affected by marine volcanic activities and Mesozoic magmatic intrusions.The reef-building reached its peak stage at the Givetian,indicating a large-scale build-up of reef and inter-reef depression.In central-eastern Hunan Province,the strata-bound ore deposits belong to low-temperature ore-types without later magmatic intrusions or volcanic activities.In Hunan Province as well as many other localities in South China,the Givetian reefs played important roles in mobilizing ore-forming materials from the surrounding pre-Devonian rocks,providing spaces and passages for transporting hydrothermal fluid,and progressing mineralization and accumulation of ore-forming materials.
