柴达木盆地北缘地区砂岩型铀矿成矿条件与成矿潜力

Metallogenic Condition and Potential of Sandstone-type Uranium Deposits in the Northern Margin of Qaidam Basin

通过对柴达木盆地北缘地区地质构造背景、找矿目的层中-下侏罗统沉积体系、沉积相、岩石地球化学特征、水文地质条件、层间氧化带和铀矿化基本特征的综合研究分析,认为区内具有砂岩型铀矿成矿的地质演化背景条件,构造斜坡带发育有辫状河、三角洲等具泥-砂-泥地层结构的沉积组合,盆地蚀源区及目的层内铀含量均较高,铀源条件良好,地下水补-径-排水动力系统和水文地球化学条件良好,在目的层内已发现发育完善的层间氧化带和与层间氧化带相关的砂岩型铀矿化。总体而言,区内具有较好的砂岩型铀矿成矿地质条件,但由于喜山期以来新构造作用的强烈改造,断裂构造发育,变形作用强烈,找矿难度较大。

By way of synthetical study on geological structure setting, depositional systems and sedimen- tary facies, lithogeochemistry and hydrogeology, interlayer oxidizing zone, as well as uranium metalli- zation in the middle- lower Jurassic serie in the northern margin of Qaidam basin, it was believed that structure slope in geological evolution for sandstone - type uranium metallization was developed in the ar- ea, and sedimentary rocks combination of mudstone - sandstone - mudstone of braide river and delta faci- es was formed, uranium content are high in denude area of basin, target stratum and source rocks, charge- runoff- discharge hydrodynamic system and favorable hydrogeochemical condition, as well as fully interlayer oxidizing zone have been discovered in the basin. In general, there was good conditon sandstone- type uranium metallization in the north margin of Qaidam basin, but strong neotectonic ac- tivity in Himalayan orogeny, faulted structure and deformation made the uranium exploration quite diffi- cult.