摘要
书楼丘地区煌斑岩脉主要呈EW向展布,铀矿体往往产于煌斑岩脉与硅化带接触部位,为研究煌斑岩的组成、产出环境及其与铀成矿之间的关系,系统采集了5件样品,采用XRF法分析常量元素,ICP-MS方法分析微量元素及稀土元素。结果表明,煌斑岩w(SiO 2)为50.35%~58.21%,总体富Si;微量元素相对富集大离子亲石元素(LILE)和轻稀土元素(LREE),亏损高场强元素(HFSE)和重稀土元素(HREE),Eu为弱负异常(δEu为0.71~0.87),具有与板内玄武岩相似的微量元素地球化学特征;微量及稀土元素比值表明,书楼丘地区煌斑岩脉主要由岩石圈地幔部分熔融形成,且源区为富集型地幔,这种富集可能是煌斑岩脉在上升侵位过程中受到陆壳的混染作用造成的。此外,煌斑岩脉的侵入使围岩的力学及热力学性质发生变化,围岩中的U相对活化,使流体更易浸取围岩中的U,且煌斑岩脉中含有大量的Fe 2+及还原性气体(H 2 S,CH 4等),为铀的沉淀提供了良好的沉淀障,因此,煌斑岩脉可能为铀成矿提供了运移通道、热量及还原环境。
The lamprophyre veins in the Shulouqiu area are mainly distributed from east to west.The uranium ore bodies often occur in the contact part between the lamprophyre veins and the silicified belts.In order to study the composition,forming environment of the lamprophyre and its relationship with uranium mineralization,the article systematically collected 5 samples,using XRF method to analyze the macro elements,ICP-MS method for trace elements and rare earth elements.The results show that the mass fraction of SiO 2 in lamprophyre is 50.35%-58.21%,suggesting silicon enrichment.The trace elements are relatively enriched compared to large ion lithophile elements(LILE)and light rare earth elements(LREE).High field strength elements(HFSE)and heavy rare earth element(HREE)are depleted,with weak negative anomaly of Eu(δEu=0.71-0.87).These features are similar to the trace element geochemistry of intraplate basalt.Trace and rare earth element ratios indicate that the lamprophyre veins of Shulouqiu area were mainly formed by the partial melting of the lithospheric mantle.The source region was an enriched mantle,which could due to the contamination of the crust during the ascending emplacement process of the lamprophyre veins.In addition,the intrusion of lamprophyre veins changed the mechanical and thermodynamic properties of the country rock,resulting in the relative activation of U in the surrounding rock,which makes it easier for the fluid to leach U.With a large amount of Fe 2+and reducing gases(H 2S,CH 4,etc.),the lamprophyre veins can provide good precipitation barrier for uranium precipitation.Therefore,lamprophyre veins may provide migration channels,heat and reducing environment for uranium mineralization.
作者
罗强
刘斌
郭新文
刘文泉
祁家明
Luo Qiang;Liu Bin;Guo Xinwen;Liu Wenquan;Qi Jiaming(No.290 Research Institute,CNNC,Shaoguan 512029,Guangdong,China)
出处
《地质学刊》
CAS
2020年第1期63-70,共8页
Journal of Geology
基金
中国核工业地质局铀矿地质项目“广东省诸广矿集区铀矿资源调查评价与勘查”(201926)
“广东省仁化县高山径—黄竹坪地区铀矿普查”(201728-2)
“诸广南部深部铀矿预测评价(201836-04)
“广东省仁化县长排东南地区铀矿普查”(201728-1)”。
关键词
煌斑岩
地球化学
板内玄武岩
富集地幔
铀矿
书楼丘
广东诸广
lamprophyre
geochemistry
intraplate basalt
enriched mantle
uranium deposit
Shulouqiu
Zhuguang in Guangdong
