Sandstone Petrologic Feature And Uranium Enrichment Regularity Of Xishanyao Formation In Hoxtolgay Basin

In this paper, the research object is petrologic feature and uranium enrichment regularityof the Jurassic Xishanyao Formation in the Hoxtolgay basin. Based on the thin sectionanalysis, scanning electron microscope, X-ray Diffraction and total rock analysis, the paperdiscusses the altered minerals, major elements, trace elements and REE characteristics of thesandstone in alteration zone. By comparing Hoxtolgay basin with typical sandstone-typeuranium deposits, the paper analyzes the relation between petrologic feature and uraniummineralization, which is expected to provide evidence for metallogenic condition andprognosis.By analyzing the scanning electron microscope and X-ray Diffraction, it is revealed thatmain alteration minerals are argillation, limonitization, carbonatization and pyritization;According to the relative percentage content of clay minerals from high to low, there arekaolinite, smectite, chlorite and illite; Based on the relative percentage content of kaoliniteand smectite, it is revealed that the aqueous medium transfered from alkaline(oxidized zone)to acid(transitional zone), and then to weak acid(primary zone).After studying on the major elements, it is revealed that the reducibility of transitionalzone is stronger, followed by primary zone; the clay content of transitional zone is betweenoxidized zone and primary zone; U shows a positive correlation with Na2O and a negativecorrelation with TiO2, Al203. The enrichment of uranium have closer relationship with thecontent of plagioclase and higher content of clay mineral is not conducive to the enrichmentof uranium.Based on the analysis result of trace elements, it is showed that uranium is transferred inoxidized zone and enriched in transitional zone; U has a symbiotic relationship with Re, Bi, W,Ba, Sb, Mo, Ni, Cr and the other trace elements dose not present a good zonality; U has thehighest correlation coefficient with Re, followed by Mo and W, Tl.By analyzing the REE, the conclusion is that the chondrite normalized REE patterns ofthe sandstone shows right declined lines with negative Eu anomaly and not apparent Ceanomaly; Along with the fluid migration, rare earth elements appear loss phenomenon; Thedifferential degree of REE is the highest in oxidation zone, while the lowest in the primaryzone.Based on comprehensive analysis of the petrologic feature of the Jurassic XishanyaoFormation in the Hoxtolgay basin, the point of view is that study area is similar to typicalsandstone-type uranium deposits on uranium enrichment regularity.