陕南光石沟伟晶岩型铀矿床黑云母矿物化学研究及其对铀成矿的启示  

MINERAL CHEMISTRY OF BIOTITE AND ITS IMPLICATIONS FOR URANIUM MINERALIZATION IN GUANGSHIGOU PEGMATITE-TYPE URANIUM DEPOSIT,SOUTH SHAANXI PROVINCE

作　　者：陈佑纬[1] 毕献武[1] 胡瑞忠[1] 董少花[1] 程德进 冯张生 

机构地区：[1]中国科学院地球化学研究所,贵州贵阳550002 [2]陕西核工业地质局224大队,陕西西安710024

出　　处：《矿物岩石》2013年第4期17-28,共12页Mineralogy and Petrology

基　　金：国家自然科学基金(41103027);中国科学院矿床地球化学国家重点实验室"十二五"项目群(SKLODG-ZY125-03)

摘　　要：黑云母是伟晶岩型铀矿床中重要的矿物,它广泛地存在于产铀相关的花岗岩及伟晶岩之中,同时与伟晶岩矿床中主要铀矿物-晶质铀矿的产出有着十分密切的关系。选择与我国光石沟伟晶岩型铀矿床密切相关的灰池子二长花岗岩、大毛沟白岗岩、伟晶岩类中黑云母作为研究对象,系统的电子探针矿物化学分析结果显示:花岗岩、白岗岩和伟晶岩中黑云母均具有富集铁、钛,亏损挥发性组分氟、氯等特征。产铀黑云母伟晶岩中黑云母相对于非产铀黑云母伟晶岩具有富Mg,Mn,贫Al,低ACNK以及氧逸度等特点。研究结果不仅表明白岗岩和伟晶岩并不是由灰池子二长花岗岩分离结晶而来,而且证明了同化混染作用不仅控制了产铀伟晶岩中黑云母的特殊结构构造以及物质组成,更是伟晶岩型铀矿产出的关键因素。Biotite is one of the important minerals in the pegmatite-type uranium deposits. It not only exists in the pegmatites and granites which have close relationship with uranium mineraliza- tion,but also is closely related with the main uranium mineral in the deposit. Biotite in the gran- ites,alaskites and pegmatites closely related with the Guangshigou pegmatite-type uranium depos- it is selected as the research subject. Based on the mineral chemistry of biotite analyzed by EM- PA,it is showed that all the biotites are characterized by rich in Mg and Mn,deplete in Ca and the volatile constituents F and C1. The biotite in U-bearing biotite pegmatites is characterized by higher content in Mg,Mn and lower in A1,ACNK and oxygen fugacity,compared to other biotite pegmatite. The results show that the alaskites and pgematites are not from the fractional crystalli- zation of the Huichizhi monzonite granite. It is also evidenced that the assimilation between the pegmatites and wall rock not only control the special structure and composition of biotite in U- bearing pegmatites,but also the key factor in forming of pegmatite-type uranium deposit.

关 键 词：伟晶岩型铀矿床 黑云母 矿物化学 同化混染 光石沟 

分 类 号：P611.12[天文地球—矿床学]