460铀-钼矿床控矿因素及矿床成因探讨

Ore-controlling factors of the 460 U-Mo deposit and its genesis discussion

460矿床是上世纪80年代在冀北沽源中生代火山断陷盆地西部发现的大型铀-钼矿床。在对该矿床野外实地调研的基础上,结合矿床地质详查和矿床专题科研报告的综合分析,对矿床的控矿因素进行了系统总结。研究结果表明,矿床受NE向断裂(F45)和火山构造的联合控制;火山活动晚期沿断裂和中心式火山机构侵入的次流纹斑岩体是矿床定位的决定性因素;铀-钼矿化主要产于次流纹斑岩体产状变异部位或接触带附近;容矿构造为次流纹斑岩体接触带构造、隐爆角砾岩和J3z3-5层流纹岩中的层间裂隙带。研究认为,铀矿化受断裂构造、火山机构、岩浆活动、热液蚀变等作用的复合控制,其中火山口-火山通道相的次流纹斑岩体是主要的控矿因素。

The 460 deposit is a large U-Mo deposit found in western part of the Mesozoic volcanic fault basin in Guyuan of Northern Hebei in 1980＇s. Based on the field research of this deposit, combined with the comprehensive analysis of the geological survey and special report for the scientific research in this ore field, it has summaized the ore-controlling factors systematically. The result has shown that the deposit is jointly controlled by NE trend fault （F45） with volcanic structure the determining factor of the deposit orientation is the aggressive sub-rhyolite porphyry intruded along faults and in the organization of central volcano The U- Mo mineralization mainly occurred in the differentiation part of sub-rhyolite-porphyry occurrence as well as the vicinity of the contacting zone the ore-bearing structure has included the contacting-zone structure of sub-rhyolite porphyry, crptoexplosion breccia and the fissure zone between layers of the rhyolite occurred in J3z3-5 layer. It has believed that U mineralization has been compoundly controlled by fault structure, volcanic organization, magmatic activities, and hydrothermal alteration etc. with the main ore-controlling factor being the sub-rhyolite porphyry in volcanic caldera or volcanic conduits.