The Yutangba Se deposit is a rare high-Se deposit in the world and it is well known for its high contents of Se, which reach 8590×10+{-6} . The ore-hosted rocks are dominated by cherts that have been well develop...The Yutangba Se deposit is a rare high-Se deposit in the world and it is well known for its high contents of Se, which reach 8590×10+{-6} . The ore-hosted rocks are dominated by cherts that have been well developed. Enrichment of selenium in Se-rich ores is obviously controlled by stratigraphic position and lithological character. The closer the rocks are to the Maokou Formation cherts, the more they contain selenium, but in case the stratigraphic horizons are close to one another, the enrichment of selenium would be controlled by lithological character. In the Se ores and abandoned stone coal pile at the Yutangba Se deposit there have been found large amounts of independent Se minerals, for instance, achavalite and a variety of forms of native selenium. Native selenium minerals present in the abandoned stone coal pile are the outcome of a combination of natural factors and anthropologic activities. For example, lime making will create a closed environment favoring the growth of native selenium, and the reduction of selenium will lead to its secondary enrichment. Starting with the study of ore-forming fluids. Systematic studies have been conducted on fluid inclusions separated from the main ore veins in the mining district for their homogenization temperatures, salinities and density, and the results show that fluid inclusions contained in ores from the Yutangba Se deposit are large in number and diverse in form, dominated by primary ones. The homogenization temperatures of two types of fluid inclusions are within the range of {173.2}-{247.5℃}, individually up to 300℃ or even higher; the salinities of fluids in fluid inclusions in quartz and calcite are {5.9%}-{10.1%} and {3.9%}-{4.5%}, respectively; their densities vary from {0.79}-{0.93} g/cm+3. Extensive discovery of Se minerals due to secondary enrichment of selenium in the stone coal provides important clues to the improvements on the metallurgical and recovery technologies for selenium in the black shale series of China, and also is of great significance in expanding selenium reserves and relax the situation of lacking selenium resources on a global scale.展开更多
Within the range of 0.01 km\+2 mini\|landscape in Yutangba, Enshi, Hubei Province, the content of Se in corn is very high. The average Se contents in root, stem, leaf and seed of corn were estimated to be 4.36±3....Within the range of 0.01 km\+2 mini\|landscape in Yutangba, Enshi, Hubei Province, the content of Se in corn is very high. The average Se contents in root, stem, leaf and seed of corn were estimated to be 4.36±3.27mg/kg, 3.08±2.24 mg/kg, 9.74±7.62mg/kg, and 8.07±5.02mg/kg, respectively. The research results show that there is a significantly positive correlation between corn selenium and soil selenium, and thus according to the distribution of Se in corn, three subregions can be divided in Yutangba. The content of selenium in corn is controlled by that of soil. A little variation in selenium content in soil will lead to a considerable corresponding variation in corn. So it is deduced that the organs that contain relatively high Se in plants may be used as a sensitive selenium indicator of Se levels in the environment.展开更多
At the top of the Lower Permian Maokou Formation limestones are developed carbonaceous cherts (Plm3), which constitute the dominant seleniferous layer of the Yutangba Se deposit. The cherts contain as much Se as 1646&...At the top of the Lower Permian Maokou Formation limestones are developed carbonaceous cherts (Plm3), which constitute the dominant seleniferous layer of the Yutangba Se deposit. The cherts contain as much Se as 1646×10-6 on average. In addition, they are rich in organic carbon, AI2O3, Si2O, but poor in S. In addition to Se, as well as Mo, Cd, V, and Co, etc are also highly enriched in the cherts. The chert samples are characterized by low ∑REE, slight LREE enrichment, relatively heavy Si isotope enrichment, and insignificant variations in δ30Si value within the range of 1.1‰-1.2‰. Generally, it can be judged from the major element, trace element and REE data and the Si isotopic characteristics that the Yutangba seleniferous cherts were formed in the shallow sea to semi-deep sea anoxic environments and their formation is controlled chiefly by bio-chemical processes.展开更多
The selenium isotopic ratios have been measured in the Yutangba Se deposit, Hubei Province, China. The results show that the δ 82/76SeNIST values vary from -12.77‰ to 4.93‰, which is the largest Se iso- topic varia...The selenium isotopic ratios have been measured in the Yutangba Se deposit, Hubei Province, China. The results show that the δ 82/76SeNIST values vary from -12.77‰ to 4.93‰, which is the largest Se iso- topic variation found so far in natural terrestrial samples. The sample Ytb-5 of high-selenium carbona-ceous shale has the lightest Se isotopic composition with a δ 82/76SeNIST value of -12.77‰. On the basis of variations of Se isotope in the deposit along with other geological and geochemical evidence, the "redox model" is suggested to favor the explanation of the occurrence of native Se in the deposit. The application to the Yutangba Se deposit with the discovery of large Se isotopic fractionation for natural samples indicates the potential of Se isotope as a new geochemical tracer.展开更多
文摘The Yutangba Se deposit is a rare high-Se deposit in the world and it is well known for its high contents of Se, which reach 8590×10+{-6} . The ore-hosted rocks are dominated by cherts that have been well developed. Enrichment of selenium in Se-rich ores is obviously controlled by stratigraphic position and lithological character. The closer the rocks are to the Maokou Formation cherts, the more they contain selenium, but in case the stratigraphic horizons are close to one another, the enrichment of selenium would be controlled by lithological character. In the Se ores and abandoned stone coal pile at the Yutangba Se deposit there have been found large amounts of independent Se minerals, for instance, achavalite and a variety of forms of native selenium. Native selenium minerals present in the abandoned stone coal pile are the outcome of a combination of natural factors and anthropologic activities. For example, lime making will create a closed environment favoring the growth of native selenium, and the reduction of selenium will lead to its secondary enrichment. Starting with the study of ore-forming fluids. Systematic studies have been conducted on fluid inclusions separated from the main ore veins in the mining district for their homogenization temperatures, salinities and density, and the results show that fluid inclusions contained in ores from the Yutangba Se deposit are large in number and diverse in form, dominated by primary ones. The homogenization temperatures of two types of fluid inclusions are within the range of {173.2}-{247.5℃}, individually up to 300℃ or even higher; the salinities of fluids in fluid inclusions in quartz and calcite are {5.9%}-{10.1%} and {3.9%}-{4.5%}, respectively; their densities vary from {0.79}-{0.93} g/cm+3. Extensive discovery of Se minerals due to secondary enrichment of selenium in the stone coal provides important clues to the improvements on the metallurgical and recovery technologies for selenium in the black shale series of China, and also is of great significance in expanding selenium reserves and relax the situation of lacking selenium resources on a global scale.
文摘Within the range of 0.01 km\+2 mini\|landscape in Yutangba, Enshi, Hubei Province, the content of Se in corn is very high. The average Se contents in root, stem, leaf and seed of corn were estimated to be 4.36±3.27mg/kg, 3.08±2.24 mg/kg, 9.74±7.62mg/kg, and 8.07±5.02mg/kg, respectively. The research results show that there is a significantly positive correlation between corn selenium and soil selenium, and thus according to the distribution of Se in corn, three subregions can be divided in Yutangba. The content of selenium in corn is controlled by that of soil. A little variation in selenium content in soil will lead to a considerable corresponding variation in corn. So it is deduced that the organs that contain relatively high Se in plants may be used as a sensitive selenium indicator of Se levels in the environment.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 49633110) Graduate School of the Chinese Academy of Sciences.
文摘At the top of the Lower Permian Maokou Formation limestones are developed carbonaceous cherts (Plm3), which constitute the dominant seleniferous layer of the Yutangba Se deposit. The cherts contain as much Se as 1646×10-6 on average. In addition, they are rich in organic carbon, AI2O3, Si2O, but poor in S. In addition to Se, as well as Mo, Cd, V, and Co, etc are also highly enriched in the cherts. The chert samples are characterized by low ∑REE, slight LREE enrichment, relatively heavy Si isotope enrichment, and insignificant variations in δ30Si value within the range of 1.1‰-1.2‰. Generally, it can be judged from the major element, trace element and REE data and the Si isotopic characteristics that the Yutangba seleniferous cherts were formed in the shallow sea to semi-deep sea anoxic environments and their formation is controlled chiefly by bio-chemical processes.
基金Supported by "West Light" of Chinese Academy of Sciences, Guizhou Natural Science Foundation, Knowledge Innovation Programme of Chinese Academy of Sciences (Grant Nos. KZCX3-SW-125 and KZCX2-102)
文摘The selenium isotopic ratios have been measured in the Yutangba Se deposit, Hubei Province, China. The results show that the δ 82/76SeNIST values vary from -12.77‰ to 4.93‰, which is the largest Se iso- topic variation found so far in natural terrestrial samples. The sample Ytb-5 of high-selenium carbona-ceous shale has the lightest Se isotopic composition with a δ 82/76SeNIST value of -12.77‰. On the basis of variations of Se isotope in the deposit along with other geological and geochemical evidence, the "redox model" is suggested to favor the explanation of the occurrence of native Se in the deposit. The application to the Yutangba Se deposit with the discovery of large Se isotopic fractionation for natural samples indicates the potential of Se isotope as a new geochemical tracer.
