陆家堡凹陷四方台组砂体非均质性特征与铀成矿关系

Heterogeneity of Sand Body in Sifangtai Formation and Its Relationship With Uranium Mineralization in Lujiapu Sag

近几年松辽盆地南部找矿成果显著,随着找矿工作的不断推进,对新地区新层位探索不断加强,因此在陆家堡凹陷地区研究四方台组铀成矿特征至关重要。文章通过对区内钻孔砂体的厚度、含砂率,隔挡层数及隔层厚度的数据统计,分别从平面及垂向两方面入手,对陆家堡凹陷区内四方台组砂体的非均质性特征进行研究,寻找其与铀成矿的关系。陆家堡凹陷地区四方台组砂体在平面上受沉积相带控制明显,铀矿化往往产于冲积扇相扇状河道砂体中;在垂向上受隔挡层数及隔层厚度影响,铀矿化出现在隔挡层数少、厚度小的地区,且随着隔挡层厚度的增加,见矿率随之降低。研究发现区内砂体厚度在50~70 m、含砂率在50%~70%、隔挡层层数在2~6层,隔层厚度在16~32 m时,成矿概率高。

In recent years,remarkable uranium exploration achievements has been accomplished in the southern Songliao Basin due to the exploration of new area and new horizon.Therefore,it is very important to summarize the metallogenic characteristics of the new area and layer.In this paper heterogeneity characteristics of sand body was studied in the plane and the vertical on the thickness and percentage of sand body,the confining layers number and thickness of Sifangtai Formation in Lujiapu sag,and their relationship to uranium mineralization.Sand body of Sifangtai Formation in Lujiapu sag are obviously controlled by sedimentary facies.In the plane,the uranium mineralization usually occured in the fanshaped channel sand bodies of alluvial fan.In the vertical,the uranium mineralization was affected by the number and the thickness of confining layers,and occurs in the areas with few confining layers and less thickness.It was found that the highest ore-forming probability will occur while the sand body is of 50~70 m thick and 50%~70%percentage,and the confining layer is in 2~6 layers of 16~32 m thick.