内蒙古银宫山地区闪长玢岩脉锆石U-Pb同位素年代学、地球化学特征及与铀矿化关系研究  

Study on Zircon U-Pb Geochronology,Geochemistry of the Diorite Porphyrite Vein and Their Relationship With Uranium Mineralization in Yingongshan Area,Inner Mongolia

作　　者：李华明 李玲 王果 苗爱生 LI Huaming;LI Ling;WANG Guo;MIAO Aisheng(Geological Party No.208,CNNC,Baotou,Inner Mongolia 014010,China)

机构地区：[1]核工业二○八大队,内蒙古包头014010

出　　处：《铀矿地质》2022年第4期732-747,共16页Uranium Geology

基　　金：中国核工业地质局地勘费项目“内蒙古中部火山岩型铀矿资源调查评价与勘查”(编号:201904)资助。

摘　　要：银宫山地区位于内蒙古中部,是我国重要的有色金属矿集区,近年来在该地区陆续发现多处热液型铀矿化,矿化在空间上与侵入大东山花岗岩体中的闪长玢岩脉关系密切。为深入探讨闪长玢岩脉与铀矿化的关系,文章开展了锆石U-Pb年代学、岩石地球化学等研究,结果表明,研究区出露的闪长玢岩脉年龄为242~232 Ma,形成于印支期早阶段。铀矿化蚀变的闪长玢岩脉成岩后受到211 Ma和128 Ma两次热事件的影响,并伴随U的高度富集,铀矿化成因可能与大东山花岗岩体原生含铀矿物中铀的活化迁移作用有关。岩石地球化学研究表明,闪长玢岩脉在铀富集矿化过程中发生了明显的Mn、Mg、Sr和Pb的带入,同时伴随有Na的带出,而稀土元素含量未发生显著的变化。Located in the middle of Inner Mongolia,Yingongshan is an important area of non-ferrous metal ore concentration in China and many hydrothermal uranium mineralization have been discovered recently,which are closely related to the diorite porphyrite vein in Dadongshan granite.This paper studied the relationship between diorite porphyrite veins and uranium mineralized by zircon U-Pb chronology and geochemistry.Zircon LA-ICP-MS dating results showed that the exposed diorite porphyrite veins in the study area were formed at an Early Indosinian stage(242~232 Ma).Uranium mineralized diorite porphyrite veins were affected by two thermal events of 211 Ma and 128 Ma after diagenesis,accompanied by high enrichment of uranium.The uranium mineralization may be related to the activation and migration of uranium in primary uranium minerals of the Dadongshan granite body.Geochemistry study showed that Mn,Mg,Sr,Pb were brought into the diorite porphyrite veins while Na of the diorite porphyrite veins were brought out during the process of uranium enrichment and mineralization.However the REE contents did not change significantly.

关 键 词：闪长玢岩脉 锆石U-PB同位素年代学 铀矿化 银宫山 

分 类 号：P588.122[天文地球—岩石学] P619.14[天文地球—地质学]