There are abundant hydrothermal sedimentary structures and plant fragment fossils in the siliceous rocks from the Lincang Ge deposit. The major element compositions of these siliceous rocks are characterized by high c...There are abundant hydrothermal sedimentary structures and plant fragment fossils in the siliceous rocks from the Lincang Ge deposit. The major element compositions of these siliceous rocks are characterized by high content SiO2, low TiO2 and Al2O3concentrations, and low Al/(Al+Fe+Mn) ratios (0.010 on average). The siliceous rocks are distinctly enriched in Ge, Sb, As, W, and secondly enriched in Cs, U, Mo and Tl. Their total REE content are generally less than 1μg/g, LREE relatively concentrated, and the values of Eu anomaly and Ce anomaly vary from 0.452 to 5.141 and 0.997 to 1.174, respectively. Their NAS-normalized REE patterns are plain or left-inclined. The Oxygen isotope compositions of these siliceous rocks are similar to those of the hydrothermal siliceous sinter. The above characteristics, as well as the geological setting of the deposit, indicate these siliceous rocks formed in continental hydrothermal envi- ronment. As the interlayer or cliff of the Ge-rich coal seams, siliceous rocks tightly contacted with ore-body, and the contents of Ge in siliceous rocks vary from 5.6 to 360 μg/g (78 μg/g on aver- age). The Ge content increased in coal which close to the siliceous rocks. With the increase of Ge content, the typical trace element ratios (i.e., Ge/Ga, Nb/Ta and U/Th) and REE patterns of Ge-rich coal are more close to those of the siliceous rocks. The Ge concentrated in coal seams of the Lincang Ge deposit might be transported by the hydrothermal water, which demonstrated by the siliceous rocks, during the coal-forming processes.展开更多
The mechanism of formation of the Lincang germanium deposit is discussed in thelight of the spatial distribution of Ge-rich coal and siliceous rocks, the sulfur isotopic composi-tion of pyrite in the Ge-rich coal, the...The mechanism of formation of the Lincang germanium deposit is discussed in thelight of the spatial distribution of Ge-rich coal and siliceous rocks, the sulfur isotopic composi-tion of pyrite in the Ge-rich coal, the variation of Ge abundance in the coal seams and the geo-chemical characteristics of the siliceous rocks. The results show that the siliceous rocks interca-lated with the coal seams were deposited from a hydrothermal medium through which germani-um was enriched in the coal beds. The primary source of germanium is thought to be the Ge-rich granite in the basement of the sedimentary basin.展开更多
基金jointly supported by the State Key Fundamental Research Developing and Planning Program of China(Grant No.G1999043210)the National Natural Science Foundation of China(Grant No.40302018).
文摘There are abundant hydrothermal sedimentary structures and plant fragment fossils in the siliceous rocks from the Lincang Ge deposit. The major element compositions of these siliceous rocks are characterized by high content SiO2, low TiO2 and Al2O3concentrations, and low Al/(Al+Fe+Mn) ratios (0.010 on average). The siliceous rocks are distinctly enriched in Ge, Sb, As, W, and secondly enriched in Cs, U, Mo and Tl. Their total REE content are generally less than 1μg/g, LREE relatively concentrated, and the values of Eu anomaly and Ce anomaly vary from 0.452 to 5.141 and 0.997 to 1.174, respectively. Their NAS-normalized REE patterns are plain or left-inclined. The Oxygen isotope compositions of these siliceous rocks are similar to those of the hydrothermal siliceous sinter. The above characteristics, as well as the geological setting of the deposit, indicate these siliceous rocks formed in continental hydrothermal envi- ronment. As the interlayer or cliff of the Ge-rich coal seams, siliceous rocks tightly contacted with ore-body, and the contents of Ge in siliceous rocks vary from 5.6 to 360 μg/g (78 μg/g on aver- age). The Ge content increased in coal which close to the siliceous rocks. With the increase of Ge content, the typical trace element ratios (i.e., Ge/Ga, Nb/Ta and U/Th) and REE patterns of Ge-rich coal are more close to those of the siliceous rocks. The Ge concentrated in coal seams of the Lincang Ge deposit might be transported by the hydrothermal water, which demonstrated by the siliceous rocks, during the coal-forming processes.
文摘The mechanism of formation of the Lincang germanium deposit is discussed in thelight of the spatial distribution of Ge-rich coal and siliceous rocks, the sulfur isotopic composi-tion of pyrite in the Ge-rich coal, the variation of Ge abundance in the coal seams and the geo-chemical characteristics of the siliceous rocks. The results show that the siliceous rocks interca-lated with the coal seams were deposited from a hydrothermal medium through which germani-um was enriched in the coal beds. The primary source of germanium is thought to be the Ge-rich granite in the basement of the sedimentary basin.
