| Mengqiguer sandstone-type uranium deposits located in the southern of the basin,which is one of the mainly sandstone-type uranium deposits in Yili basin,But also the first domestic construction of thousands of tons of inland sandstone-type uranium-producing base.Based on the observation and description of sandstone macroscopic characteristics in the field,the sandstone of the ore-bearing strata in the mining area is the main research object.Based on the comprehensive application of Petrology,Mineralogy,Geochemistry and other multi-disciplinary tests,we study the characteristics of mineralogical characteristics,petrographic characteristics,ore characteristics,detrital zircon U-Pb dating,provenance tracing and tectonic evolution of the Mengqiuer uranium deposit in detail.Research indicates:(1)The type of ore-bearing sandstone is mainly composed of lithic sandstone,which overall separation is poor,low compositional maturity,low structural maturity,strong diagenesis,a series of alterations such as kaolinization,illite and so on.The development of the dissolution and epigenetic alteration during diagenesis provides favorable conditions for uranium enrichment,and the new clay minerals show adsorption during uranium enrichment.In the oxidation reduction environment,and ultimately affect the migration and precipitation of uranium.(2)There are two occurrences of uranium in Mengqiuer uranium deposit: One is independent uranium mineral and the other is dispersed adsorption.The mainly independent uranium minerals are as follows: Pitchblende and a small amounts of coffinite and brannerite.Pitchblende is irregular granular,colloidal or radial distribution in the quartz crystal or cement,the overall development of colloidal crack structure is obvious;Coffinite was dependent-structured and crystal irregular granular,kidney distribution in the carbon and pyrite edge.Titanium uranium irregular stars dotted on the edge of rutile or fissure,uranium in state of dispersed adsorption mainly adsorbed in the carbon dust,and UO2 content changes greatly.(3)Using the accurate sandstone clastic composition quantitative analysis method.The Sangonghe Formation is a set of mixed re-cycle orogenic belt transition to theorogenic belt,and finally to the evolution of lithic and orogenic belt transition,The Xishanyao Formation is a set of orogenic belt transition to the evolution of lithic and orogenic belt transition.(4)The U-Pb age of the zircons in the lower part of the Sangonghe Formation of the Mengqiguer uranium deposit is between 300~50 Ma;The zircon U-Pb ages in the upper part of the Sangonghe Formation are between 350~00 Ma,The U-Pb age in the lower part of the Xishanyao Formation is between 350~400 Ma,and the peak value of zircon U-Pb in the upper part of the Xishanyao Formation is between 300~350 Ma,and the other is the age of Cambrian.It is show that the main source of the sandstone in the Mengqiquer uranium deposit comes from Wusunshan Dahalajunshan Formation Volcanic rocks in southern margin of the basin and Paleozoic granite that is distribut in Nalati area in the south,followed by the Precambrian basement in Yining-Central Tianshan Mountains plate Baluntai area and Nalati region. |
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