Widespread in more than ten provinces of southern China are the Lower Cambrian black argillaceous-arenaceous rock series consisting of black carbonaceous shales,black carbonaceousargillo-siliceous rocks,black carbonac...Widespread in more than ten provinces of southern China are the Lower Cambrian black argillaceous-arenaceous rock series consisting of black carbonaceous shales,black carbonaceousargillo-siliceous rocks,black carbonaceous silicolite and black silicolite and black carbonaceous argillaceous siltstone.The Ni,Mo,V,Cu,U,Ba,Ag,P contents of these series are usually several to tens of times higher than their average values in shales.As viewed from lithological sequence,element association and evolution,these black series can be diveided into two types.There occur a variety of deposits in the black rock series,such as phosphorite deposits,Ni-Mo-V polymetal deposits and 'Stone coal' seams.According to ore composition,texture and structure,the phosphorite deposits fall into three types,i.e.,thick-bedded,lenticular and nodular,The Ni-Mo-V polymetal deposits,V deposits and reworked sedimentary CU-U-Cd polymetal deposits in terms of their element assiciation and ore genesis.As for the stratiform deposits in the black rock series,three mineralization stages have been recognized,i.e.,the formation of phosphorite deposits,of Ni-Mo polymetal deposits and of V-Cu-U-Cd polymetal deposits as well as of ':stone coal' seams.Evidence strongly suggests that lower organisms have played an important role in mineralization. Our studies indicate that the Lower Cambrian black argillaceous-arenaceous rock series in southern China and their associated stratiform deposits occur generally in the basal parts of a big sedimentary cycle,i.e.,the initial period of a transgression,or in the fine detrital-siliceous formation between two carbonate formatons,formed in a humid climatic zone between two arid ones.As for the environment of deposition,it is suggested that the Lower Cambrian black argillaceous-arenaceous rock series and associated stratiform deposits(excluding thick-bedded phosphorite deposits)were formed mainly in a restricted and poorly-fed sea basin of stagnant shallow water containing abundant lower or ganisms and organic matter under statically hydrodynamic conditions.展开更多
Studies of sedimentology, ore micrascopy and geochemistry have been carried out on a Ni- Mo- multi-element-bearing black shales of the Lower Cambrian Niutitang Formation. Chemical analyses, electronprobe analyses, X-r...Studies of sedimentology, ore micrascopy and geochemistry have been carried out on a Ni- Mo- multi-element-bearing black shales of the Lower Cambrian Niutitang Formation. Chemical analyses, electronprobe analyses, X-ray powder diffraction methods,optical, spectrographic and DTA techniques and electron photomicrographs arc also used in the research. Conclusive information has been obtained about the mode of occurrence of nickel,molybdenum and other elements, about their distribution within the Niutitang Formation, and about their concentrations in various types of sedimentary rocks. A preliminary discussion is also given to the depositional sequence of the Niutitang Formation as well as to thc controlling factors for the enrichment of these elements. Nickel and molybdenum are mainly enriched in thin-bedded and leuticular bodies within which Pt, Pd, Os, Au, TR, Se, T1, Cu, Zn etc. are also concentrated, showing a complex assemblage of elements and various occurrences. Major ore minerals are vaesite, polydymite, millerite, gersdorffite, jordisite, pyrite, chalcopyrite, tennantite.sphalerite. Gold and silver occur as Ag-bearing native gold. Barium is presented as barite. Selenium and thallium are considered to be related to pyrite. Rarc earths, on the other hand, are concentrated in phophorite and phosphorous nodules. The black shales have undergone sedimentation-diagenesis, epigenetie alteration and secondary oxidation. The depositional environment was strongly reducing. Organic materials played a definite part in the formation of siliceous matter, pyrite and some other sulfides. Nickel-molybdenum-multi-element-rich beds are found in the transitional zone from phosphorite to hlae.k siliceous rocks. It is believed that changes in depositional environment are the principal factors controlling the enrichment of the multi-element.展开更多
Sinian strata (isotopic ages ranging from 1900-850 m.y.) in Oihsien, county and its vicinity have been studied in more detail from the standpoint of sedimentary geochemistry. Average chemical composition of various se...Sinian strata (isotopic ages ranging from 1900-850 m.y.) in Oihsien, county and its vicinity have been studied in more detail from the standpoint of sedimentary geochemistry. Average chemical composition of various sedimentary rocks in the Sinian sequence (sandstone, siltstone, shale, dolomite and limestone) have been calculated.The periodicity and general trend as exhibited in the course of evolution of element association have been demonstrated by mathematical statistics based on numerious chemical analyses and semiquantitative spectroscopic data with the aid of electronic computer. In accordance with the above results the classification of elements are proposed on a more reasonable ground. Considerable attention has been paid to the periodicity and evolutionary eharacterictics of rocks, minerals and elements. The mode of occurrence of elements is examined in the light of trace-element concentrations and the relative coefficients between them in different components (clastic debris, clay, and ete.) from a variety of rocks and carbonates. Finally, the relationship between background abundances of elements and mineralization, and the effect of submarine eruption on sedimentation and the enrichment of some elements, for example, K, St, Mn, B, P, Pb and Zn, have also been dealt with.展开更多
The formation of many metallic and non metallic ore deposits is a result of coupling of mineralization, related to anoxic environment and regional, or global background. Interaction, concordance and continual developm...The formation of many metallic and non metallic ore deposits is a result of coupling of mineralization, related to anoxic environment and regional, or global background. Interaction, concordance and continual development of the mineralization and environmental background control the large to superlarge scale of ore deposits. Three kinds of ore forming models related to anoxic environment and three important background patterns are suggested. The turning period of geological history is favorable to the formation of large to superlarge ore deposits.展开更多
文摘Widespread in more than ten provinces of southern China are the Lower Cambrian black argillaceous-arenaceous rock series consisting of black carbonaceous shales,black carbonaceousargillo-siliceous rocks,black carbonaceous silicolite and black silicolite and black carbonaceous argillaceous siltstone.The Ni,Mo,V,Cu,U,Ba,Ag,P contents of these series are usually several to tens of times higher than their average values in shales.As viewed from lithological sequence,element association and evolution,these black series can be diveided into two types.There occur a variety of deposits in the black rock series,such as phosphorite deposits,Ni-Mo-V polymetal deposits and 'Stone coal' seams.According to ore composition,texture and structure,the phosphorite deposits fall into three types,i.e.,thick-bedded,lenticular and nodular,The Ni-Mo-V polymetal deposits,V deposits and reworked sedimentary CU-U-Cd polymetal deposits in terms of their element assiciation and ore genesis.As for the stratiform deposits in the black rock series,three mineralization stages have been recognized,i.e.,the formation of phosphorite deposits,of Ni-Mo polymetal deposits and of V-Cu-U-Cd polymetal deposits as well as of ':stone coal' seams.Evidence strongly suggests that lower organisms have played an important role in mineralization. Our studies indicate that the Lower Cambrian black argillaceous-arenaceous rock series in southern China and their associated stratiform deposits occur generally in the basal parts of a big sedimentary cycle,i.e.,the initial period of a transgression,or in the fine detrital-siliceous formation between two carbonate formatons,formed in a humid climatic zone between two arid ones.As for the environment of deposition,it is suggested that the Lower Cambrian black argillaceous-arenaceous rock series and associated stratiform deposits(excluding thick-bedded phosphorite deposits)were formed mainly in a restricted and poorly-fed sea basin of stagnant shallow water containing abundant lower or ganisms and organic matter under statically hydrodynamic conditions.
文摘Studies of sedimentology, ore micrascopy and geochemistry have been carried out on a Ni- Mo- multi-element-bearing black shales of the Lower Cambrian Niutitang Formation. Chemical analyses, electronprobe analyses, X-ray powder diffraction methods,optical, spectrographic and DTA techniques and electron photomicrographs arc also used in the research. Conclusive information has been obtained about the mode of occurrence of nickel,molybdenum and other elements, about their distribution within the Niutitang Formation, and about their concentrations in various types of sedimentary rocks. A preliminary discussion is also given to the depositional sequence of the Niutitang Formation as well as to thc controlling factors for the enrichment of these elements. Nickel and molybdenum are mainly enriched in thin-bedded and leuticular bodies within which Pt, Pd, Os, Au, TR, Se, T1, Cu, Zn etc. are also concentrated, showing a complex assemblage of elements and various occurrences. Major ore minerals are vaesite, polydymite, millerite, gersdorffite, jordisite, pyrite, chalcopyrite, tennantite.sphalerite. Gold and silver occur as Ag-bearing native gold. Barium is presented as barite. Selenium and thallium are considered to be related to pyrite. Rarc earths, on the other hand, are concentrated in phophorite and phosphorous nodules. The black shales have undergone sedimentation-diagenesis, epigenetie alteration and secondary oxidation. The depositional environment was strongly reducing. Organic materials played a definite part in the formation of siliceous matter, pyrite and some other sulfides. Nickel-molybdenum-multi-element-rich beds are found in the transitional zone from phosphorite to hlae.k siliceous rocks. It is believed that changes in depositional environment are the principal factors controlling the enrichment of the multi-element.
文摘Sinian strata (isotopic ages ranging from 1900-850 m.y.) in Oihsien, county and its vicinity have been studied in more detail from the standpoint of sedimentary geochemistry. Average chemical composition of various sedimentary rocks in the Sinian sequence (sandstone, siltstone, shale, dolomite and limestone) have been calculated.The periodicity and general trend as exhibited in the course of evolution of element association have been demonstrated by mathematical statistics based on numerious chemical analyses and semiquantitative spectroscopic data with the aid of electronic computer. In accordance with the above results the classification of elements are proposed on a more reasonable ground. Considerable attention has been paid to the periodicity and evolutionary eharacterictics of rocks, minerals and elements. The mode of occurrence of elements is examined in the light of trace-element concentrations and the relative coefficients between them in different components (clastic debris, clay, and ete.) from a variety of rocks and carbonates. Finally, the relationship between background abundances of elements and mineralization, and the effect of submarine eruption on sedimentation and the enrichment of some elements, for example, K, St, Mn, B, P, Pb and Zn, have also been dealt with.
文摘The formation of many metallic and non metallic ore deposits is a result of coupling of mineralization, related to anoxic environment and regional, or global background. Interaction, concordance and continual development of the mineralization and environmental background control the large to superlarge scale of ore deposits. Three kinds of ore forming models related to anoxic environment and three important background patterns are suggested. The turning period of geological history is favorable to the formation of large to superlarge ore deposits.
