460火山岩型铀-钼矿床的构造-矿化分带及成矿模式研究

460矿床是产在华北地台北缘上侏罗统次流纹斑岩体内的一个大型铀-钼矿床。矿床受次级火山断陷盆地的盆缘基底断裂(F_(45))与其派生的次级断裂(F_3)斜接复合部位控制,铀矿化分布在次流纹斑岩体中,矿床构造、矿化和围岩蚀变在垂向上的分带性十分明显,矿床的形成经历了吕梁期钾质混合岩化和晚侏罗世酸性火山岩浆活动所导致的两次铀的预富集作用,以及燕山期次流纹斑岩侵位后的酸性火山热液成矿、喜山期裂陷-玄武岩活动后的热水叠造成矿和近代的表生淋积叠造成矿等多次成矿作用阶段。460矿床是一个典型的复成因的火山岩型铀-钼矿床,可以由此建立矿床的成矿模式。

THE STRUCTURE-MINERALIZATION ZONING AND AN APPROACH TO THE METALLOGENETIC MODEL FOR VOLCANIC TYPE MOLYBDENUMURANIUM DEPOSIT NO. 460

The deposit No. 460 is a large molybdenum-uranium deposit occurring in the subrhyoliteporphyry body of Upper Jurassic Series at the northern margin of North China Platform. The deposit is controlled by the juxtaposition-composite part of the marginal basement fault (F_(45)) and its derivative secondary fault (F_3). The uranium mineralization occurs in the subrhyolite-porphyry body. The vertical zoning of the structure, mineralization and wall rock alteration of the deposit are very evident. The formation process of the deposit underwent two preconcentrations of uranium caused by the potassic migmatization during the Luliang stage and the Late Jurassic acid volcanic magmatic activity, as well as three stages of metallogenesis: the acid volcanic hydrothermal metallogenesis after emplacement of the subrhyolite-porphyry body in the Yanshanian stage; the hydrothermal superposedreworking metallogenesis after the taphrogenesis-basalt activity in the Himalayan stage; and the supergene infiltration and superposed-reworking metallogenesis of the recent ground water. So the deposit No. 460 is a typical polygenetic volcanic type molybdenum-uranium deposit. Thereby, it is possible to establish a metallogenetic model for the deposit.