| As one of key metals,rhenium(Re)is extensively used in high-tech fields,and irreplaceable due to its excellent physical and chemical properties.Most of Re in the world is concentrated in molybdenite of porphyry deposits,but Re concentrations vary significantly on the scales of ore deposits,samples and even individual molybdenite.At present,understanding of such difference is still unclear.Dexing copper ore field is the most representative in eastern China,consisting of Fujiawu,Tongchang and Zhushahong deposits.Re reserves can reach 1000 t of the Dexing copper ore field.Although considerable studies have been done for the Dexing copper ore field such as age of diagenetic and ore forming,the sources of ore forming fluid and ore forming materials,genesis of deposit,but the research on the distribution and enrichment mechanism of Re in molybdenite is very rarely.This thesis focused on the Fujiawu and Tongchang deposits.Properties and evolution process of ore forming fluid,by using quartz cathodoluminescence,temperature measurement of fluid inclusions and quartz element compositions,and distribution characteristics and enrichment mechanism of Re in molybdenite,by using EPMA,LA-ICP-MS,Mapping and XRD,were systematically studied.(1)The results of temperature data of fluid inclusions and LA-ICP-MS of quartz in Fujiawu and Tongchang deposits showed that they had similar fluid evolution processes.However,the temperature of the fluids,in the same metallogenic stage,in Fujiawu was higher than that in Tongchang,and the fluid in Fujiawu had lower salinity in the main metallogenic stage.the p H of early metallogenic stage in Tongchang was higher than that in Fujiawu,and the p H in late metallogenic stage in Tongchang is lower.The decrease of temperature,fluid boiling and the change of p H may be the main reasons for the precipitation of Cu and Mo.(2)The molybdenite,the main Re-bearing mineral,can be divided into two types,coarse-grained leaf-shaped molybdenite and fine-grained aggregate molybdenite,and some molybdenite had kinks.The results of LA-ICP-MS trace elements mapping showed that the distribution of Re in molybdenite is extremely uniform,the coarse-grained leaf-shaped molybdenite was more likely to have high value areas of Re.And Re depletion in deformed molybdenite observed in deformed may shows deformation can induce Re loss and redistribution(3)The results of EPMA and LA-ICP-MS analysis showed that Re contents of molybdenite varied significantly in Fujiawu and Tongchang deposits.There was a weak negative correlation between Re and Cu,W,W+Sn contents in molybdenite.With the increasing of Sc contents,the upper limit of Re contents in molybdenite were significantly reduced,and there was no correlation between other elements and Re.From the early stage to the late stage,the S/Mo ratios and Re contents of molybdenite gradually increased,and the average content of Re in fine-grained aggregate molybdenite was slightly higher than coarse-grained leaf-shaped molybdenite.The Re contents of molybdenite,the same metallogenic stages and same types,in Tongchang were higher than that in Fujiawu.(4)The results of XRD analysis showed that the samples of high Re-bearing and low Re-bearing molybdenite were all 2H polytypes in Fujiawu and Tongchang deposits,which indicated that there was no obvious correlation between the Re content of molybdenite and molybdenite polytypes.(5)The temperature,salinity and p H were the dominant factors leading to the heterogeneous enrichment of rhenium in molybdenite in Dexing copper ore field. |
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