Based on characteristics of unaltered rocks and REE patterns, ion-adsorpted RE deposits can be devided into four types including Y-rich and Eu-poor granites, Y-mid and and Eu low granites, Eu-rich granites, Eu-mid vol...Based on characteristics of unaltered rocks and REE patterns, ion-adsorpted RE deposits can be devided into four types including Y-rich and Eu-poor granites, Y-mid and and Eu low granites, Eu-rich granites, Eu-mid volcanic and subvolcanic rocks. The distribution of REE contents in weathered profiles shows an are-shaped pattern. It indicates that the REE contents are enriched in full weathered and upper parts of sub-weathered zones. The REE patterns-in weathered crusts also demonstrate characteristics essentially inherited from those in unaltered rocks; On the other hand, cerium; has a positive anomaly in soil zone and negative anomalies in full weathered and sub-weathered zones. Gradual decrease in the slopes of the REE pattern curves indicates that HREE contents are more enriched than LREE in lower portion of the pro files. REE abundance in unaltered rocks and appropriate climate are essential conditions for ion adsorpted deposits. According to experiments of the REE adsorption on clay minerals, REE concentrations, pH values and ion strength in solutions significantly affect adsorption contents and partition coefficients. The distribution of the REE in weathered profiles are controlled by percolation and adsorption coupling in groundwater-rock interaction systems.展开更多
In this paper the geochemical characteristics of rare earth elements in Guposhan granite complex in Nanling Area,South China,is systematically studied,and the balance of REE distribution in rock-forming minerals, whic...In this paper the geochemical characteristics of rare earth elements in Guposhan granite complex in Nanling Area,South China,is systematically studied,and the balance of REE distribution in rock-forming minerals, which contain only 21.47～29.71 wt% of total REE in granites,is calculated.The petrogenetic relationship be- tween three different stages of the granites in the complex is discussed,and a geochemical model is suggested for the formation of granitic magma in early stage by partial melting of the crustal basement rocks containing more REE than that in the late stage.It shows that a ion-adsorption type of REE deposit could ocuur in the weath- ering crust on the early stage granite.Rb-Sr isotope isochron dating of the first stage medium-coarse-grained K-feldspar granite shows that its age is 146.5 Ma and initial ^(87)Sr/^(86)Sr ratio is 0.71198.展开更多
文摘Based on characteristics of unaltered rocks and REE patterns, ion-adsorpted RE deposits can be devided into four types including Y-rich and Eu-poor granites, Y-mid and and Eu low granites, Eu-rich granites, Eu-mid volcanic and subvolcanic rocks. The distribution of REE contents in weathered profiles shows an are-shaped pattern. It indicates that the REE contents are enriched in full weathered and upper parts of sub-weathered zones. The REE patterns-in weathered crusts also demonstrate characteristics essentially inherited from those in unaltered rocks; On the other hand, cerium; has a positive anomaly in soil zone and negative anomalies in full weathered and sub-weathered zones. Gradual decrease in the slopes of the REE pattern curves indicates that HREE contents are more enriched than LREE in lower portion of the pro files. REE abundance in unaltered rocks and appropriate climate are essential conditions for ion adsorpted deposits. According to experiments of the REE adsorption on clay minerals, REE concentrations, pH values and ion strength in solutions significantly affect adsorption contents and partition coefficients. The distribution of the REE in weathered profiles are controlled by percolation and adsorption coupling in groundwater-rock interaction systems.
基金The research is supported by the National Natural Science Foundation of China
文摘In this paper the geochemical characteristics of rare earth elements in Guposhan granite complex in Nanling Area,South China,is systematically studied,and the balance of REE distribution in rock-forming minerals, which contain only 21.47～29.71 wt% of total REE in granites,is calculated.The petrogenetic relationship be- tween three different stages of the granites in the complex is discussed,and a geochemical model is suggested for the formation of granitic magma in early stage by partial melting of the crustal basement rocks containing more REE than that in the late stage.It shows that a ion-adsorption type of REE deposit could ocuur in the weath- ering crust on the early stage granite.Rb-Sr isotope isochron dating of the first stage medium-coarse-grained K-feldspar granite shows that its age is 146.5 Ma and initial ^(87)Sr/^(86)Sr ratio is 0.71198.
