江西相山铀矿田铀矿物稀土元素特征及富集机制探讨  

Charateristics of REE in Uranium Minerals and Its Enrichment Mechanism in Xiangshan Uranium Ore Field,Jiangxi

作　　者：刘政国 林锦荣[1] 王勇剑[1] 韩美芝 胡志华[1] LIU Zhengguo;LIN Jinrong;WANG Yongjian;HAN Meizhi;HU Zhihua(Beijing Research Institute of Uranium Geology,Beijing 100029,China)

机构地区：[1]核工业北京地质研究院,北京100029

出　　处：《铀矿地质》2023年第3期375-394,共20页Uranium Geology

基　　金：中核集团“第四代铀矿勘查关键技术研究与示范(第一阶段)”项目“基于大数据的砂岩型铀矿三维预测技术研究”(编号:地SD04)资助。

摘　　要：铀矿物是铀矿床勘探与选冶的重要研究对象。相山铀矿田是我国最大的火山岩型铀-多金属矿田,主要发育有早期碱交代和晚期酸交代两期铀矿化,但目前对这两期铀矿化中铀矿物的地球化学特征尚缺乏系统的对比研究。文章运用电子探针和激光剥蚀电感耦合等离子体质谱对相山铀矿田两期铀矿化矿石中铀矿物稀土元素特征进行研究。结果显示,相山铀矿田碱交代和酸交代型铀矿化矿石中铀矿物类型均包含钛铀矿、铀石和沥青铀矿,碱交代型铀矿化矿石中铀矿物以钛铀矿、铀石为主,酸交代型铀矿化矿石中铀矿物以沥青铀矿为主。碱交代型铀矿化矿石中铀矿物稀土元素配分模式为右倾型,富集La、Ce和Nd等元素;酸交代型铀矿化矿石中铀矿物稀土元素配分模式为左倾型,富集Yb、Er和Dy等元素。酸交代型铀矿化矿石中沥青铀矿相对富集重稀土元素,与国内外其他类型的铀矿床相比其成矿过程有明显特殊性,这可能与成矿流体富F-有关;深部沥青铀矿较浅部富集重稀土元素的原因可能是深部沥青铀矿结晶温度高于浅部;相对于铀石和钛铀矿等铀矿物,重稀土富集对沥青铀矿有倾向性可能是因为沥青铀矿形成的过程与CO_(3)^(2-)和Cl^(-)关系密切。In Xiangshan uraninm ore field,the largest volcanic-type uranium ore field in China,two stages of uranium mineralization has been identified:the early alkaline metasomatized mineralization and late acidic metasomatized mineralization.However,there are few comparative studies on th geochemical characteristics of uranium minerals from the two stages uranium mineralization.In this paper,EPMA and LA-ICP-MS were used to study the characteristics of rare-earth element of uranium minerals from the two episodes of uranium mineralization in Xiangshan uranium ore field.The uranium minerals in Xiangshan mainly include brannerite,uranite and pitchblende,the uranium minerals in alkaline metasomatized mineralization are mainly brannerite and pitchblende,while the pitchblende is dominated in acidic metasomatized mineralization.The REE pattern of uranium minerals in alkaline alternation mineralization was right-leaning,and the elements of La,Ce and Nd were enriched.Uranium minerals in acid metamorphosis uranium mineralization are left-leaning,rich in elements such as Yb,Er and Dy.The extraordinary enrichment of HREE in pitchblende in the acidic metasomatized mineralization was compared with other types of uranium deposits at home and abroad,it was found that the mineralization process of acid meaomatization may be related to the Mineral-bearing fluids fluid rich in F-.The reason why pitchblende in the deep part of the deposit is richer in HREE than the shallow is that the crystallization temperature of pitchblende in the deeper position is higher than that of pitchblende in the shallower position.Compared with uranite and brannerite,HREE tends to be enriched in pitchblende,which may be related to CO_(3)^(2-)and Cl^(-)due to the formation process of pitchblende.

关 键 词：微区分析 重稀土 沥青铀矿 铀矿化类型 相山铀矿田 

分 类 号：P619.14[天文地球—矿床学] P595[天文地球—地质学]