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
The silver contents of organic matter in the host rocks of the Songxishale-hosted Ag-Sb deposit of northeastern Guangdong, South China, have been directly determinedusing the electron microprobe technique. The silver ...The silver contents of organic matter in the host rocks of the Songxishale-hosted Ag-Sb deposit of northeastern Guangdong, South China, have been directly determinedusing the electron microprobe technique. The silver contents in two types of organic matter, marinevitrinite and solid bitumen, vary in the range from 100 X 10^(-6) to 350 X 10^(-6), which are fromtens of times to thousands of times higher than those of the host rocks in the ore deposit. Theaverage silver content of the organic matter is also several times higher than the pay grade ofsilver for commercial mining of the ore deposit. It is quite obvious that the organic matter of thehost rocks in the ore district is characterized by an anomalous enrichment of silver. The results ofthis study indicate that the silver anomalies in the organic matter have been derived from both thehost rocks and the silver-bearing fluids of the Songxi black shale ore source. In the course ofsedimentation and later hydrothermal reworking, organic matter was able to entrap the element silverfrom source rocks and silver-bearing fluids through complexation and reduction, so that silvercould be further enriched (or precipitated) in the solid bitumen. The quantitative assessment inthis study suggests that the distribution of solid bitumens in the ore district may be considered anindication for mineral exploration.展开更多
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.
基金the National Natural Science Foundation of China(Grant 49872037)the State Education Ministry Foundation for excellent young teachers the Youth Science Foundation of Jiangsu Province(Grant BQ96007)
文摘The silver contents of organic matter in the host rocks of the Songxishale-hosted Ag-Sb deposit of northeastern Guangdong, South China, have been directly determinedusing the electron microprobe technique. The silver contents in two types of organic matter, marinevitrinite and solid bitumen, vary in the range from 100 X 10^(-6) to 350 X 10^(-6), which are fromtens of times to thousands of times higher than those of the host rocks in the ore deposit. Theaverage silver content of the organic matter is also several times higher than the pay grade ofsilver for commercial mining of the ore deposit. It is quite obvious that the organic matter of thehost rocks in the ore district is characterized by an anomalous enrichment of silver. The results ofthis study indicate that the silver anomalies in the organic matter have been derived from both thehost rocks and the silver-bearing fluids of the Songxi black shale ore source. In the course ofsedimentation and later hydrothermal reworking, organic matter was able to entrap the element silverfrom source rocks and silver-bearing fluids through complexation and reduction, so that silvercould be further enriched (or precipitated) in the solid bitumen. The quantitative assessment inthis study suggests that the distribution of solid bitumens in the ore district may be considered anindication for mineral exploration.
