Genesis of Caledonian fine-grained granites and its significance for Mo-polymetallic prospecting in Xiangshan area,central Jiangxi Province
The Yanshanian metallogenic events occurred frequently in South China,and the granites formed in this period are highly studied,while the study about the Caledonian granites are relatively weak.The deep magma and uranium-polymetallic mineralization in the Xiangshan ore field and its surrounding areas are complex.In recent years,some new metal mineralization spots such as Pb,Zn,Mo and Sn have been found around the Xiangshan area,and massive fine-grained granite has been exposed in its depth.In order to find out the relationship between the fine-grained granite and Mo mineralization,the zircon LA-ICP-MS U-Pb chronology,trace element geochemistry and Re-Os isotope chronology of molybdenite were studied in this paper.The fine-grained granite was formed at 410±2.5 Ma,Late Caledonian Period.The weighted average age of the molybdenite Re-Os isotope is 405±1.2 Ma,which is similar to the fine-grained granite.Combined with the characteristics of trace elements of zircon,the Ti crystallization temperature of zircons are 572 ℃～585 ℃.Oxygen fugacityΔFMQ=-9.62～-2.52,(Ce4+/Ce3+)zircon=0.9;(Ce/Nd)/Y ratio(0～0.012)is low,Dy/Yb ratio(0.23～0.42)is high,indicating that the water content of magma is not high.It indicates that although the granites are closely related to Sn-Mo poly-metal,they do not have the conditions for forming large Tin-Mo poly-metal deposits.The Caledonian tectonic background of the Xiangshan area in Jiangxi Province is complex.In the discrimination diagram of tectonic background,the samples mainly fall within the transition range of intraplate/non-orogenic environment and magmatic arc/orogenic environment.However,by summarizing the geochemical data of Caledonian granites in central Jiangxi Province,it is found that the tectonic background of Early Caledonian granites is obviously different from that of Late Caledonian granites,and the early orogenic compression environment is dominant,while the later orogenic extension environment is dominant.
ZirconMolybdeniteOxygen fugacityCaledonianXiangshan area in central Jiangxi Province
万方数据
维普
