甘肃省龙首山地区芨岭铀矿区蚀变特征分析

Characteristics of alteration in Jiling uranium mining area in Longshoushan area of Gansu

文章重点对龙首山芨岭铀矿区近矿围岩蚀变特征、分带特征以及蚀变期次进行研究,蚀变大致可分为高温钾钠混合交代阶段、区域性钾交代阶段、中低温热液钠钙交代阶段、矿化期钠交代阶段,其中与成矿关系密切的是矿化期钠交代阶段。通过对新水井铀矿床各中段的系统取样分析表明:与正常花岗岩相比钠交代蚀变岩的Cu、Pb、Ni、Sn、V、Zr、As等微量元素含量显著增加,而W、Rb的含量明显减少;钠交代蚀变岩随着埋深增大其Na2O、SiO2、Al2O3含量减小。Fe2O3、FeO、CaO含量增加;钠交代蚀变岩具有的碱性(A型)花岗岩型稀土分配型式、富集型(La/Sm)N特点、明显的Eu亏损和重稀土显著增加等特征。

This paper focused on the study of the alteration characteristics,zoning characteristics and altera-tion stages of the near-ore wall rock in Jiling uranium ore field.The alteration was divided into four phases：high temperature K-Na mixed metasomatic stage,areal K metasomatic stage,low-medium temperature Na-Ca metasomatic stage and Na metasomatic stage in the mineralization phase,among which the mineralization is closely related to Na metasomatic stage in the mineralization phase.The systematic sampling analysis on each medium section of Xinshuijing U deposits suggested that：compared to those in normal granites trace el-ement content of Cu,Pb,Ni,Sn,V,Zr and As in Na metasomatic altered rocks increased significantly while the content of W and Rb decreased obviously;and content of Na2 O,SiO2 and Al2 O3 decreased as the depth of Na metasomatic altered rocks increased.The content of Fe2 O3 ,FeO and CaO increased;Na meta-somatic altered rocks were characterized by alkali （Type A）granite type REE pattern,enriched （La/Sm）N , obvious Eu depletion and significant addition of HREE.