The Dounan manganese deposit is a typical large-scale marine sedimentary manganese deposit of the Middle Triassic in China. The metallogenic environment and change process directly dictate the migration, enrichment, a...The Dounan manganese deposit is a typical large-scale marine sedimentary manganese deposit of the Middle Triassic in China. The metallogenic environment and change process directly dictate the migration, enrichment, and precipitation of Mn. To better understand its metallogenetic environment, a detailed study was undertaken involving field observation, mineralogical and geochemical and M?ssbauer spectroscopic analyses. The major findings are as follows:(1) Lithofacies paleogeography, sedimentary structural characteristics, and geochemical indexes indicate that the deposits were formed in an epicontinental marine sedimentary basin environment of normal salinity;(2) there were three ore phases including Mn oxides, Mn carbonates, and mixed Mn ores. The ore minerals found were braunite, manganite, Ca-rhodochrosite, manganocalcite, and kutnahorite. Petrographic and mineralogical information indicates that the metallogenic environment was a weakly alkaline and weakly oxidized to weakly reduced environment, and the mineralization occurred near the redox interface;(3) the V/(V + Ni)ratios, δCe and Fe^(2+)/Fe^(3+) found in profiles of Baigu and Gake ore sections show that the redox conditions of the ore-forming environment were continuously changing; and(4) three Fe species, α-Fe_2O_3, para-Fe^(3+), and para-Fe^(2+),were found in hematite and clay mineral samples using M?ssbauer spectrum analysis. The presence and distribution of these Fe species indicate that the deposit was formed in a typical sedimentary environment during the mineralization process. In summary, our study showed that redox was a key factor controlling the mineralization of the Dounan manganese deposit. Our results have led us to the conclusion that transgression and regression caused fluctuations in sea level, which in turn caused the change of the redox environment. M?ssbauer spectroscopy is an effective tool for studying the redox conditions of the paleoenvironment in which sedimentary manganese deposits were formed.展开更多
Taking Dounan International Flower Industry Park in Chenggong District for example, neighboring environment and other tourism resources are combined on the basis of the five planned functional areas(fl ower trade and ...Taking Dounan International Flower Industry Park in Chenggong District for example, neighboring environment and other tourism resources are combined on the basis of the five planned functional areas(fl ower trade and expo area, comprehensive service and distribution area, post-harvest treatment and information service area, international fl ower research and exhibition area, international fl ower enterprise exhibition and supporting service area), and recreational functions designed to build it into a comprehensive industrial and recreational park with sightseeing, leisure, and science popularization functions. Integration and adjustment of leisure spaces in Dounan International Flower Industry Park focus on the following aspects: re-plan the layout of leisure spaces; industrial park promotes restructuring of leisure spaces; residential functions are transferred to new leisure spaces; commercial service industry promotes leisure spaces; government transforms its functions and expands functions of leisure spaces; new technology pushes forward the change of residents' leisure time structure, so as to improve leisure functions of Dounan International Flower Industry Park in an all-around way.展开更多
基金supported by the Natural Science Foundation of China(NSFC No.41376080)the 12th Five-Year Plan project of the State Key Laboratory of Ore-deposit Geochemistry,Chinese Academy of Sciences(SKLODG-ZY125-08)
文摘The Dounan manganese deposit is a typical large-scale marine sedimentary manganese deposit of the Middle Triassic in China. The metallogenic environment and change process directly dictate the migration, enrichment, and precipitation of Mn. To better understand its metallogenetic environment, a detailed study was undertaken involving field observation, mineralogical and geochemical and M?ssbauer spectroscopic analyses. The major findings are as follows:(1) Lithofacies paleogeography, sedimentary structural characteristics, and geochemical indexes indicate that the deposits were formed in an epicontinental marine sedimentary basin environment of normal salinity;(2) there were three ore phases including Mn oxides, Mn carbonates, and mixed Mn ores. The ore minerals found were braunite, manganite, Ca-rhodochrosite, manganocalcite, and kutnahorite. Petrographic and mineralogical information indicates that the metallogenic environment was a weakly alkaline and weakly oxidized to weakly reduced environment, and the mineralization occurred near the redox interface;(3) the V/(V + Ni)ratios, δCe and Fe^(2+)/Fe^(3+) found in profiles of Baigu and Gake ore sections show that the redox conditions of the ore-forming environment were continuously changing; and(4) three Fe species, α-Fe_2O_3, para-Fe^(3+), and para-Fe^(2+),were found in hematite and clay mineral samples using M?ssbauer spectrum analysis. The presence and distribution of these Fe species indicate that the deposit was formed in a typical sedimentary environment during the mineralization process. In summary, our study showed that redox was a key factor controlling the mineralization of the Dounan manganese deposit. Our results have led us to the conclusion that transgression and regression caused fluctuations in sea level, which in turn caused the change of the redox environment. M?ssbauer spectroscopy is an effective tool for studying the redox conditions of the paleoenvironment in which sedimentary manganese deposits were formed.
基金Supported by Scientific Research Program of Kunming University(XJW13006)
文摘Taking Dounan International Flower Industry Park in Chenggong District for example, neighboring environment and other tourism resources are combined on the basis of the five planned functional areas(fl ower trade and expo area, comprehensive service and distribution area, post-harvest treatment and information service area, international fl ower research and exhibition area, international fl ower enterprise exhibition and supporting service area), and recreational functions designed to build it into a comprehensive industrial and recreational park with sightseeing, leisure, and science popularization functions. Integration and adjustment of leisure spaces in Dounan International Flower Industry Park focus on the following aspects: re-plan the layout of leisure spaces; industrial park promotes restructuring of leisure spaces; residential functions are transferred to new leisure spaces; commercial service industry promotes leisure spaces; government transforms its functions and expands functions of leisure spaces; new technology pushes forward the change of residents' leisure time structure, so as to improve leisure functions of Dounan International Flower Industry Park in an all-around way.
