Coal Organic Matter Characteristic And Metallogenic Significance In Daying Sandstone-type Uranium Deposit,Ordos Basin

The sandstone-type uranium deposit has a close relationship with coal organic matter.The relation may be spatial,statistical or geochemical.This paper studies the sandstone-type uranium deposit in Daying,northern ordos basin.It based on the collect the predecessors' research result and combine with the field geological investigation,drilled core observe.The sample from different alteration sandstone of oxidation zone,transition zone,reduction zone,which contain lenticular carbon strip and carbonaceous clastic.Try to analysis the geological and geochemical characteristics of coal organic matter in Zhiluo formation in study area.Meanwhile,to explor the relationship between coal organic matter and uranium mineralization.The coal organic matter as a mechanism of uranium mineralization,which will greatly enrich sandstone-type uranium metallogenic theory and prospecting practices.Studied the index test of samples' geochemical characteristics and coal organic maceral characteristics,so that it can be better to analyse the relationship between organic carbon and uranium content and the characteristics of organic macerals and maturity of organic matter.Through kerogen elemental composition determination to illustrate the coal organic matter types and geochemical properties.At the same time,the characteristics of soluble organic matter in the samples are tested to illustrate the source rock types,sedimentary environment and source rock maturity.Combined with the above test,we also have get the extraction of humus organic matter in coal and have test the uranium content characteristics to explore the relationship between coal organic matter and uranium mineralization.Making clear of the type and geological characteristics of coal organic matter in Daying uranium deposit.There are much lenticular carbon strip and carbonaceous clastic bands in the rich uranium deposits,and there is a positive correlation between organic carbon and uranium content in each alteration zone.The coal organic maceral is given priority to with vitrinite,It reflects that the characterized of humic coal is low maturity and the evolution stage of immature lignite.The microspore and cutin in the coal organic matter.with strong fluorescence phenomenon and Ro of it in the transition zone is higher than other alteration zones,there are bright white bands in the macerals.These three phenomena may be due to the high uranium content in the transition zone,the radioactivity of uranium pronoted the evolution of organic matter.Reveals the coal organic matter mainly occurred in the deep buried stage and the kerogen type mainly is type ?,which.has strong adsorption ability.The results of organic geochemistry indicate that the organic matter is mainly in the anoxic and reductive sedimentary environment of transitional brackish water or freshwater lake,and the maturity is low.The soluble organic matter in the ore bearing sandstone is characterized of low carbon number,the organic matter in the organic intercalation is dominated by higher plant material.Through detrction the index of Pr/nC17,Ph/nC18 and combined with saturated hydrocarbon chromatogram(m/z=85)found in the UCM bulge phenomenon.It is mainly because of the degradation of microorganisms in the later stage of higher plants,which shows the characteristics of low carbon number.However,microbial degradation is good for uranium mineralization.Through the separation of humic substances and the analysis of uranium content,finding that coal organic matter and uranium mineralization has close relationship.It is revealed that the main origin of organic geochemical zoning of the sandstone type uranium deposits in the large scale,which mainly depends on good lithofacies paleogeograohic conditions for enrichment of organic matter in the transition zone establish foundation;Different sources of organic matter in the transition zone and caused transition zone of organic carbon content increased.The test of extraction and separation of humic substances shows that humic acid played a key role in the uranium mineralization of coal organic matter.After discussion that the mechanism of coal organic matter on uranium mineralization and enrichment mainly include reduction,adsorption,cation exchange,coordination and microbial degradation of organic matter.