银额盆地查干德勒苏坳陷水文地球化学与地下水铀成矿特征OA

As a hydrogenic uranium deposit,the mineralization process of sandstone-type uranium deposits is closely related to the hydrogeochemical characteristics of groundwater.Exploring this relationship is of great significance in understanding the metallogenic regularity and prospecting potential of sandstone-type uranium deposits.This study takes the Chagandelsu depression in linge-Ejin basin as the research case,and hydrochemical analysis and hydrogeochemical modeling were employed to systematically investigate the groundwater hydrogeochemistry and uranium mineralization characteristics of the Wulansuhai formation(K2w)and the Bayingebi formation(K1b).The results show that groundwater in the Wulansuhai formation is neutral to weakly alkaline and generally occurs in an oxidizing environment,with a hydrochemical type of Cl·SO4-Na.Groundwater in the Bayingebi formation is weakly acidic to weakly alkaline,with a relatively high uranium concentration(mean value of 0.127 mg·L-1).Its hydrochemical types are mainly HCO3·SO4-Na and SO4·HCO3-Ca·Na·Mg,and uranium in water mainly exists in the forms of UO2(CO3)34-and UO2(CO3)22-.In the piedmont slope area on the southeast of Celaomiao,the groundwater of the Bayingebi formation occurs in a relatively reducing environment,with multiple uranium concentration anomalies.Uranium exists as U(OH)4 in this area,and the saturation index of uraninite(SI>0),Eh reaction condition index(RCIEh<0),and uranium concentration reaction condition index(RCICU>0)collectively indicate that uranium is in a state of precipitation.Therefore,it is considered that the piedmont slope area on the southeast of Celaomiao possesses favorable hydrogeochemical conditions for uranium mineralization and is a prospecting target area for sandstone-type uranium exploration worthy of further investigation.