江西相山沙洲矿床铀的存在形式和迁移特征探讨:来自诱发裂变径迹的证据  

A Study on Existing Forms and Migration Process of Uranium at Shazhou Deposit, Jiangxi Province, China : Evidences from Induced Fission Tracks

作　　者：张玉燕[1] 李子颖[1] 黄志章[1] 李秀珍[1] 

机构地区：[1]核工业北京地质研究院中核集团铀资源勘查与评价技术重点实验室,北京100029

出　　处：《高校地质学报》2012年第4期639-646,共8页Geological Journal of China Universities

基　　金：国防基础科研项目(A0120060596-6)

摘　　要：相山沙洲铀矿床产于斑状黑云母二长花岗岩中。本文采用诱发裂变径迹方法,对矿区花岗质围岩及其蚀变岩石中铀的存在形式和分布状态进行了研究,共区分出围岩中铀的五种存在形式,即副矿物中的类质同像铀、显微或超显微粒状铀矿物、造岩矿物中的吸附铀、包裹体中的铀,以及简单铀氧化物矿物,并根据来源将蚀变岩石中的铀划分为来源于花岗岩原岩的继承铀和来源于成矿流体的叠加铀两类。经过交代蚀变作用,造岩矿物中的铀含量明显降低,大部分含铀副矿物消失。铀被带出并进入热液流体,后主要聚集在蚀变矿物周边和沿裂隙分布,或被新生矿物吸附。交代蚀变作用改变铀的存在形式,造成铀在岩石中的迁移和预富集,从而有利于铀的成矿作用。Shazhou uranium deposit occurs in the porphyritic biotite monzonitic granite. Existing forms and distribution characteristics of uranium in the granitic wall rocks and the alteration process at the Shazhou deposit are studied by means of induced fission tracks in this paper. Five existing forms of uranium in the altered granitic wall rocks are identified： i.e., isomorphic uranium in accessory minerals, microscopic-ultramicroscopic uranium mineral grains, adsorbed uranium in rock-forming minerals, uranium in fluid inclusions, and simple uranium oxside minerals. According to the uranium sources in the altered granitic wall rocks, the uranium in the alterated rocks can be subdivided into two categories： i.e., inherited uranium derived from original granite and superimposed uranium derived from ore-forming hydrothermal solutions. During hydrothermal alteration, uranium contents in major rock-forming minerals significantly decreased, and most uranium-bearing accessory minerals disappeared after metasomatism. Metasomatic alteration could move uranium out from granitic wall rocks to hydrothermal fluids, and the activated uranium could be at last concentrated nearby and in the fissures of the alterated minerals, or be adsorbed by the newly formed minerals. Metasomatie alteration changed the existing forms and caused migration and preliminary concentration of uranium, which would be favorable for uranium mineralization.

关 键 词：沙洲铀矿床 花岗质围岩 铀的存在形式 诱发裂变径迹 蚀变作用 

分 类 号：P539.2[天文地球—古生物学与地层学]