| This dissertation was funded by key production research projects of China Nuclear Industry Geological Survey,which named "The Study on Locating Conditions and Expanding Direction of Rich and Giant Ore Body in Zoige Uranium Ore Field" Regarding the typical 510-1 uranium deposit as research subject,the author studied detailedly the sedimentary system characteristics of ore-bearing rock series basing on summarizing and deeply analyzing of abundant references from previous researchers. Through the analysis and comparison of trace elements,rare earth elements and isotopes of hydrothermal minerals such as calcite,quartz and pyrite which are intensely related with mineralization,the sources,nature,the transportation and evolution of ore-forming fluid in uranium deposit were explored,and the mechanism of mineral deposition and enrichment was found out.The author also set up a mantle fluid ore-forming model of ore deposit.The innovative achievements and views are as follows:1.The author found for the first time that the vertical zoning of gangue minerals (quartz and calcite)in 510-1 uranium ore deposit showed an "acid top and alkaline bottom" rule.Quartz veins were developed on the top of ore deposit(level No.1),both of quartz veins and calcite veins were developed in the mid(level No.2 to No.4),while on the bottom of ore deposit(level No.5 to No.6 and below),only calcite veins were developed but no quartz veins were found.The research indicated that there existed an "acid and alkali isolation" geochemical interface nearby No.5 level of 510-1 uranium deposit(200m or so below present earth surface),which is also a high concentration position for uranium outburst of mineralization.2.Studying detailedly the macroscopic occurrence and microscopic petrology characteristics of the ore-bearing rock series in Zoige uranium ore field,the author considered that in this ore field,the ore-bearing strata rock types can be divided into three major species such as silicalite,limestone and slate.The macroscopic and microscopic characteristics of the three kinds rocks indicate that the sedimentary environment of Lower Silurian in Zoige uranium ore field is continental shelf,with alternation of the inner and outer continental shelf resulted from the growing and falling of sea level in the study area.The section structure shows a rhythm overlap of sandy slate-silty slate-argillite (micrite)-shale-silicalite.This combination of various rocks with marked difference in mechanism physical nature is a specially favorable combination for the formation of carbonaceous-siliceous-argillitic rock type uranium deposit,which is the most significant on providing quite favorable geologic environment and existence space for uranium mineralization.3.The author studied the geochemical characteristics of trace elements and rare earth elements of hydrothermal minerals such as calcite,quartz and pyrite which are intensely related with mineralization,the results showed that calcite,quartz and pyrite possess similar trace elements composing,they concentrated comparatively elements such as Sr, Zr,Ba,Zn,U,Ni,and Cr.From superficial to deep of ore deposit,the content of trace elements in calcite increased significantly.There existed a multi trace elements concentration belt nearby No.5 level interface consistent with "acid and alkali isolation" interface of ore deposit,which showed it is an important fluid ore-forming geochemical interface.Correlation analysis manifested there existing obviously positive correlation between ore-formation element U and deep-source elements like Zr,Ta,Co and Ni,which implied the deep-source ore-formation fluid.The composing and distribution patterns of rare earth elements in calcite and quartz showed the ore-forming fluid mostly came from mantle,furthermore,the values ofδCe andδEu can be used in the indication the change of oxidation and reducing environment.4.The author applying new way and present ore-forming theory,baseing on entire and systematic summarizing for stable isotopes of C,S,H and O,discussed thoroughly according different ore-forming phases and classification rule of different genetic types. The results reflected that ore-forming fluid came from deep magma or from mantle,while atmospheric water entered in late ore-forming period.5.The relationship between mantle fluid and U ore-forming was studied preliminarily,according to the results,the author considered theΣCO2 of mineralizer and heat source came from mantle,which is because upwelling mantle forced by crustal extention and deep-seated faulting produced melt blending with lower crust,during this process,mantle provided the heat and releaseΣCO2 to crust through outgassing.U mainly came from mantle-curst fluid formed by mantle-curst melt blending and the wall rock during fluid uplift.H2O mainly generated from mantle fluid and the wall rock during mantle fluid uplift,and partly from atmospheric water in the late period of ore-forming. When ore-forming hydrothermal fluid concentrated withΣCO2 and U moved up to the positon of pressure descended suddenly,outburst deposition of forming Uranium deposit occurred under decompressing boiling.According this,mantle fluid ore-forming model of ore deposit was founded.These achievements and views the author obtained brokethrough inland traditional theory on ore-forming of carbonaceous-siliceous-argillitic rock type uranium deposit, they possess extremely important directing significance for ore exploration and prediction in Zoige region from now on,meanwhile,they have new edification on exploration and survey in other inland carbonaceous-siliceous-argillitic rock type uranium deposit.
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