Characteristics and geological implications of ore-forming fluids of the Lower Cretaceous U-bearing sandstones in the southwestern Ordos basin
Sandstone-type uranium deposit is currently the most significant mining type of uranium deposit in the world.In recent years,significant breakthroughs have been made in the exploration of sandstone-type uranium deposits in the Lower Cretaceous of the southwestern Ordos basin.New uranium mineralization has been discovered in the Lower Cretaceous Huanhe and Luohe formations in areas such as Zhenyuan,Xinzhuang and Pengyang.However,the evolution of ore-forming fluids and the metallogenic process are still unclear.To determine the characteristics and the evolution process of ore-forming fluids in the U-bearing sandstones,as well as to investigate their impact on the uranium mineralization process,studies were conducted in petrography,fluid inclusions,and geochemistry of typical samples from key regions.The research indicated that the U-bearing sandstones had undergone complex diagenetic processes,including limonitization,hematitization,early carbonatization,chloritization,sulfuration,and so on.Among these,sulfuration and the associated carbonate and barite filling were closely related to uranium mineralization.The ore-forming fluids were low in salinity and temperatures ranging from 130 to 180℃,which was higher than the maximum burial temperature of the Cretaceous strata.This may be due to the influence of early Cretaceous thermal events or fluids from deep sources.The ore-forming fluids were rich in organic matter and ore-forming elements such as U,Fe,Mo,Re,CuandZn,likely originating from the"Chang 7"hydrocarbon source rocks,consistent with the characteristics of"exhalative"uranium mineralization.
国家科技期刊平台
NSTL
万方数据
