松辽盆地东南缘下白垩统沙河子组铀矿化特征及成矿潜力

依据钻孔岩心、测井曲线及样品测试数据,分析了松辽盆地东南缘下白垩统沙河子组沉积相及沉积体系、铀矿化特征,并从铀源、构造、沉积、古气候及岩石地球化学类型等方面入手,分析了铀矿成矿条件,在此基础上,评价了盆地东南缘下白垩统铀成矿潜力。研究认为,含矿目的层沙河子组上段沉积环境主要为扇三角洲前缘水下分流河道及分流河道间微相,铀矿化主要分布在扇三角洲水下分流河道微相环境或水下分流河道微相与分流河道间微相接触界面附近。含矿目的层岩石类型主要为长石石英砂岩、石英长石砂岩,次要为岩屑长石砂岩。铀矿化层岩石类型为砂岩及含泥砂岩,厚度平均0.30 m,品位平均0.0259%,平米铀量平均0.0775 kg/m2,铀镭平衡系数平均0.99,铀矿化层形态呈板状。研究区铀源丰富、构造条件适中、岩性—岩相组合较有利、古气候适宜、含矿层岩石还原能力及吸附能力较强,砂岩型铀矿成矿潜力较大。

Uranium Mineralization Characteristics and Metallogenic Potential of the Lower Cretaceous Shahezi Formation,Southeastern Songliao Basin

Based on the borehole core, logging curve and sample tess and analytical data, the sedimentary facies, sedimentary system and uranium mineralization characteristics of the Lower Cretaceous Shahezi Formation in the southeastern margin of the Songliao Basin are analyzed. From the aspects of uranium source, structure, sedimentation, paleoclimate, and rock geochemistry, the uranium ore-forming conditions are analyzed. In addition, the potential of the Lower Cretaceous uranium mineralization in the southeastern margin of the basin was evaluated. The results show that the sedimentary environment of the upper part of Shahezi, i.e., the ore-bearing target layer, is mainly the micro-facies between the subaqueous distributary channel and the distributary channel in the fan delta front. The uranium mineralization was mainly developed in the fan delta subaqueous distributary channels or near the interface between subaqueous distributary channels and subaqueous interdistributary channel microfacies. The uranium mineralization rock types are sandstone and mudstone, with an average thickness of 0.30 m, an average grade of 0.0259% , an average content of 0.0775 kg/m² of uranium, an average 0.99 radium balance coefficient, and a plate shape of the uranium mineralization layer. The study area is rich in uranium resources, moderate in structural conditions, favorable lithology suitable in paleoclimate, strong in reducing capacity and adsorption capacity of ore-bearing rocks, and large in mineralization potential of sandstone-type uranium deposits. This study provides a basis for enriching and expanding new areas of uranium prospecting in the basin.