Stratabound gold deposits in the western Qinling Mountains occur in Cambrian chert formation composed of carbonaceous chert and carbonaceous slate. The distinctive chert formation provides important grounds for the mi...Stratabound gold deposits in the western Qinling Mountains occur in Cambrian chert formation composed of carbonaceous chert and carbonaceous slate. The distinctive chert formation provides important grounds for the mineralization and controls on the formation of gold deposits. Study shows that Se is exceptionally higher in both host rocks and gold orebodies. It may be recovered as a valuable component in ores for total utilization, and in some localities even independent Se orebodies (which are mined exclusively for Se) may be delineated. In gold ore Se mainly occurs as independent minerals or in the isomorphous form in sulphides and there is a positive correlation between Se and Au.展开更多
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
基金This study was supported by the National Natural Science Foundation of China (Grant Nos. 49503048 and 49773197), a Sino-Austrian cooperation project (No. 4880099) and the Postdoctoral Science Foundation of China
文摘Stratabound gold deposits in the western Qinling Mountains occur in Cambrian chert formation composed of carbonaceous chert and carbonaceous slate. The distinctive chert formation provides important grounds for the mineralization and controls on the formation of gold deposits. Study shows that Se is exceptionally higher in both host rocks and gold orebodies. It may be recovered as a valuable component in ores for total utilization, and in some localities even independent Se orebodies (which are mined exclusively for Se) may be delineated. In gold ore Se mainly occurs as independent minerals or in the isomorphous form in sulphides and there is a positive correlation between Se and Au.
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.
