The Songxi deposit is a newly discovered large Ag (Sb) deposit. By using a suite of high-vacuum quadrupole gas mass spectrometer systems, the authors have recognized many kinds of light hydrocarbons in fluid inclusion...The Songxi deposit is a newly discovered large Ag (Sb) deposit. By using a suite of high-vacuum quadrupole gas mass spectrometer systems, the authors have recognized many kinds of light hydrocarbons in fluid inclusions of minerals. These hydrocarbons are mainly composed of C1-C4 saturated alkanes, while the contents of C2-C4 unsaturated alkenes and aromatic hydrocarbons are quite low, suggesting that the metallogenic processes have not been affected by magmatic activities. Chemical equilibrium studies show that these hydrocarbons may be a mixture of organic gases generated by microorganism activity and those by thermal cracking of type-n kerogens (kukersite) in sedimentary host rocks, and the former may constitute more than two-thirds, implying that microorganism might have played an important role in the metallogenesis. The equilibrium temperature of the latter is about 300℃, which is much higher than the geothermal temperature at the estimated depth of metallogenesis. Thus, the light hydrocarbons generated by thermal cracking of kerogens probably originated in the deep part of the sedimentary basins and then migrated through a long distance to shallower horizons of the basin. Based on the composition of light hydrocarbons in fluid inclusions, the authors infer that the Songxi deposit was formed in a continental rift. The analytical data presented in this paper support from one aspect the genetic model that the Songxi deposit may be a sedimentary hot brine transformed deposit instead of a submarine basic volcanic exhalation and low-medium temperature volcanic hydrothermal fluid filling deposit proposed by most previous researchers.展开更多
Organic geochemistry and comparisons of characteristics of the organic matter in wall rocks of the ore\|controlling strata and ores of the Lower Jurassic Songling black shale formation and the related Songxi silver\|a...Organic geochemistry and comparisons of characteristics of the organic matter in wall rocks of the ore\|controlling strata and ores of the Lower Jurassic Songling black shale formation and the related Songxi silver\|antimony deposit of northeastern Guangdong have been studied in this paper. The results show that the Lower Jurassic Songling shale formation is a suite of biologic\|rich and organic\|rich ore\|bearing marine sedimentary rocks. Micro\|components of the organic matter in the Songling black shale formation consists primarily of algae, amorphous marine kerogen, solid bitumen, and pyrobitumen. The thermal evolution of organic matter is at the over\|maturity stage. There is a general positive correlation between total organic carbon (TOC) and metallogenetic elements such as Ag and Sb in the black shale formation. Organic matter in the host rocks in the Songxi ore deposit played a role in controlling the silver\|antimony depositing environment during the forming process of the black shale ore\|bearing formation. In the absence of vitrinite, the relative level of thermal maturity calculated by solid bitumen reflectance indicates that the ore\|forming temperature of the Songxi silver\|antimony deposit was about 150-170℃, which was considered as an epithermally reworked ore deposit. The roles of organic matter in the formation of the Songxi ore deposit are a primitive accumulation of the metallogenetic elements (Ag, Sb) in the sea\|water cycle system for ore source and a concentration of metals by ion exchange or chelation as well as reduction of the oxidized metals.展开更多
1 Geological setting and samples Songxi Ag-Sb ore deposit is located in the southern margin of Yongding-Mexian Paleozoic depressionof South China Caledonian orogenic belt, and the northern margin of Zhaigang Mesozoic ...1 Geological setting and samples Songxi Ag-Sb ore deposit is located in the southern margin of Yongding-Mexian Paleozoic depressionof South China Caledonian orogenic belt, and the northern margin of Zhaigang Mesozoic volcanic basin,where a series of faults and folds formed with northwest tectonic directions. The sedimentary rocks arecomposed of Songling Group of low Jurassic system, Zhangping Group of middle Jurassic system and Quaternary System in which Songling Group can be divided into 3 lithostratigraphic units regionally, where thetwo of the units can be found there, i.e. the middle unit with gray-yellow quartz sandstone, fine sandstone and siltstone, and the upper with black shale and tuff, in which layered Ag-Sb ore bodies are deposited, and especially in the low part of quartz sandstone, siltstone, bioclastic limestone and the alteredbasalt are the main ore-bearing rocks. The ore bodies can be divided into two types of mineralization, i.e. bedded or bedded-like types and vein type.展开更多
THE Songxi Ag-Sb ore deposit is situated 28 km northeast of Meizhou city in Guangdong. It is on thenorth edge of the volcanic fault depression of the Saigangshang, which belongs to the upper Palaeozoicfault basin belt...THE Songxi Ag-Sb ore deposit is situated 28 km northeast of Meizhou city in Guangdong. It is on thenorth edge of the volcanic fault depression of the Saigangshang, which belongs to the upper Palaeozoicfault basin belt of Yong’an-Meizhou, and at the intersection of Dadong-Guidong-Jiaoling EW fault zone,Lianhuashan-Heyuan NE fault zone and Jiaoling-Shantou NW fault zone. Ag-Sb ore body occurs at thebottom of the upper part of the lower Jurassic Jingji Group (J<sub>lje-l</sub>), which is a formation of detrital rocksconsisting mainly of carbonaceous shale. 1 Geological characteristics of the ore展开更多
基金supported by the National Natural Science Foundation of China(grants 49502029,49928201 and 49773195)the Natural Sciences Foundation of Guangdong Province(No.970123)+3 种基金the Visiting Scholar Foundation of Labs in Universitiesthe Research Foundation of the State Key Laboratory for Mineral Deposits Research in Nanjing UniversityResearch Foundation of Young(originally translated as Youth)Teachers of the National Educational Department and the Training Program of Middle-aged and Young(originally translated as Medium-Youth)Teachers supported by the Lingnan Foundationsupported by the Trans-century Training Program Foundation for the Talents by the Ministry of Education
文摘The Songxi deposit is a newly discovered large Ag (Sb) deposit. By using a suite of high-vacuum quadrupole gas mass spectrometer systems, the authors have recognized many kinds of light hydrocarbons in fluid inclusions of minerals. These hydrocarbons are mainly composed of C1-C4 saturated alkanes, while the contents of C2-C4 unsaturated alkenes and aromatic hydrocarbons are quite low, suggesting that the metallogenic processes have not been affected by magmatic activities. Chemical equilibrium studies show that these hydrocarbons may be a mixture of organic gases generated by microorganism activity and those by thermal cracking of type-n kerogens (kukersite) in sedimentary host rocks, and the former may constitute more than two-thirds, implying that microorganism might have played an important role in the metallogenesis. The equilibrium temperature of the latter is about 300℃, which is much higher than the geothermal temperature at the estimated depth of metallogenesis. Thus, the light hydrocarbons generated by thermal cracking of kerogens probably originated in the deep part of the sedimentary basins and then migrated through a long distance to shallower horizons of the basin. Based on the composition of light hydrocarbons in fluid inclusions, the authors infer that the Songxi deposit was formed in a continental rift. The analytical data presented in this paper support from one aspect the genetic model that the Songxi deposit may be a sedimentary hot brine transformed deposit instead of a submarine basic volcanic exhalation and low-medium temperature volcanic hydrothermal fluid filling deposit proposed by most previous researchers.
基金ThisprojectwasjointlysupportedbytheNationalNaturalScienceFoundationofChina! (No :49872 0 37) theDoctoralProgramFoundationfor
文摘Organic geochemistry and comparisons of characteristics of the organic matter in wall rocks of the ore\|controlling strata and ores of the Lower Jurassic Songling black shale formation and the related Songxi silver\|antimony deposit of northeastern Guangdong have been studied in this paper. The results show that the Lower Jurassic Songling shale formation is a suite of biologic\|rich and organic\|rich ore\|bearing marine sedimentary rocks. Micro\|components of the organic matter in the Songling black shale formation consists primarily of algae, amorphous marine kerogen, solid bitumen, and pyrobitumen. The thermal evolution of organic matter is at the over\|maturity stage. There is a general positive correlation between total organic carbon (TOC) and metallogenetic elements such as Ag and Sb in the black shale formation. Organic matter in the host rocks in the Songxi ore deposit played a role in controlling the silver\|antimony depositing environment during the forming process of the black shale ore\|bearing formation. In the absence of vitrinite, the relative level of thermal maturity calculated by solid bitumen reflectance indicates that the ore\|forming temperature of the Songxi silver\|antimony deposit was about 150-170℃, which was considered as an epithermally reworked ore deposit. The roles of organic matter in the formation of the Songxi ore deposit are a primitive accumulation of the metallogenetic elements (Ag, Sb) in the sea\|water cycle system for ore source and a concentration of metals by ion exchange or chelation as well as reduction of the oxidized metals.
文摘1 Geological setting and samples Songxi Ag-Sb ore deposit is located in the southern margin of Yongding-Mexian Paleozoic depressionof South China Caledonian orogenic belt, and the northern margin of Zhaigang Mesozoic volcanic basin,where a series of faults and folds formed with northwest tectonic directions. The sedimentary rocks arecomposed of Songling Group of low Jurassic system, Zhangping Group of middle Jurassic system and Quaternary System in which Songling Group can be divided into 3 lithostratigraphic units regionally, where thetwo of the units can be found there, i.e. the middle unit with gray-yellow quartz sandstone, fine sandstone and siltstone, and the upper with black shale and tuff, in which layered Ag-Sb ore bodies are deposited, and especially in the low part of quartz sandstone, siltstone, bioclastic limestone and the alteredbasalt are the main ore-bearing rocks. The ore bodies can be divided into two types of mineralization, i.e. bedded or bedded-like types and vein type.
文摘THE Songxi Ag-Sb ore deposit is situated 28 km northeast of Meizhou city in Guangdong. It is on thenorth edge of the volcanic fault depression of the Saigangshang, which belongs to the upper Palaeozoicfault basin belt of Yong’an-Meizhou, and at the intersection of Dadong-Guidong-Jiaoling EW fault zone,Lianhuashan-Heyuan NE fault zone and Jiaoling-Shantou NW fault zone. Ag-Sb ore body occurs at thebottom of the upper part of the lower Jurassic Jingji Group (J<sub>lje-l</sub>), which is a formation of detrital rocksconsisting mainly of carbonaceous shale. 1 Geological characteristics of the ore
