大新铀矿床稀土元素地球化学特征及成矿机理

REE geochemistry and genesis of Daxin uranium deposit

通过对大新铀矿床各构造地球化学带的稀土元素特征参数、球粒陨石标准化配分曲线以及分层聚类谱系的分析,笔者对该矿床铀源和成矿机理进行了探讨。研究表明,大新矿床的铀主要来自于寒武纪地层,泥盆纪地层虽然有一定的预富集作用,但以作为有利的储矿空间为主。成矿过程为地下水在燕山早期和晚期构造运动产生的构造热和岩体加热下形成地下热水,并在构造驱动下沿着沟通寒武系和泥盆系的F2主断层向上运移,萃取寒武系中的活性铀,在F2正断层的次级断层F13、F23、F33等控制的富含有机质、黄铁矿的还原环境中沉淀富集,形成铀矿床。

Through the analysis on typical REE parameters,chondrite-normalized REE patterns and hierarchical cluster analysis of rocks in the structural-geochemical zonation in Daxin uranium deposit,the paper discusses the uranium source and genesis.The study shows that the uranium source mainly came from Cambrian System.The Devonian System is maily as the favorable room for saving ores in addition to pre-concentrated room for uranium.Underground water resulted from early and late Yanshanian movement and the heating of volcanic rock was turned into geothermal water and it was moved upward by the force of tectonic movement.The geothermal water mainly extracted active uranium from the Cambrian rocks,then moved upward along main regional fault（F2） connecting the Cambrian rocks and the Devonian rocks until it arrived in structural fracture zone which was controlled by secondary faults（F13,F23,F33）.At last,the uranium element in geothermal water was precipitated and concentrated into the uranium deposit in reducing environment of enriched organic material and pyrite.