纳米比亚湖山铀矿床E类白岗岩岩石学及地球化学特征  

Petrological and geochemical characteristics of E-type alaskite in the Husab uranium deposit in Namibia

作　　者：徐楷 廖志权 胡寅秋 Xu Kai;Liao Zhiquan;Hu Yinqiu(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang,Jiangxi,330013,China;The Seventh Geological Brigade of Jiangxi Bureau of Geology,Ganzhou,Jiangxi,341000,China;The Third Geological Brigade of Jiangxi Bureau of Geology,Jiujiang,Jiangxi,332100,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]江西省地质局第七地质大队,江西赣州341000 [3]江西省地质局第三地质大队,江西九江332100

出　　处：《化工矿产地质》2024年第2期132-140,共9页Geology of Chemical Minerals

摘　　要：纳米比亚湖山铀矿床的铀矿体主要产于D类和E类白岗岩体中,本次研究选择该矿床开采面上的E类白岗岩为研究对象,对其开展详细的岩相学和元素地球化学特征研究。全岩主量元素特征显示,湖山铀矿床E类白岗岩的SiO_(2)和Na_(2)O+K_(2)O含量较高,而MnO、MgO、Na_(2)O、P_(2)O_(5)以及CaO含量较低,为高钾钙碱性系列-钾玄岩系列的过铝质岩石。稀土元素具有Eu轻微亏损、轻重稀土分馏不明显的特征,具有较明显的四分组效应。微量元素特征表明Rb/Sr、Nb/Ta、Zr/Hf与全球地壳比值接近,E类白岗岩可能是壳源岩石;此外,在微量元素蛛网图中,E类白岗岩相对富集Rb、K、Th、U、Pb等大离子亲石元素,而Ba、Nb、Sr、Ti等呈较明显的负异常;Sr的亏损可能是斜长石在岩浆演化过程中分离结晶的结果,Ti的亏损则可能是钛铁氧化物分离结晶而导致,这表明E类白岗岩的岩浆结晶分异较为完全。The uranium ore bodies of the Husab uranium deposit in Namibia mainly occur in D-type and E-type alaskite masses.This study selected the E-type alaskite on the mining face of the deposit as the research object and conducted detailed petrographic and elemental geochemical characteristics work on it.The characteristics of major elements in the entire rock indicate that the E-type alaskite of the Husab uranium deposit has higher SiO_(2) and Na_(2)O+K_(2)O contents,while the MnO,MgO,Na_(2)O,P_(2)O_(5),and CaO contents are lower,and show peraluminous rock with higher potassium calc-alkaline series to potassic basalt series.The REE characteristics show that Eu element is slightly depleted and the fractionation of light and heavy rare earths is not obvious,being of a significant four-grouping effect.The characteristics of trace elements indicate that these samples are close to the global crust in the values of the Rb/Sr,Nb/Ta,Zr/Hf,and the E-type granite may be a crustal source rock;In addition,it can be seen from the trace element spider web diagram that the E-type granite is relatively rich in large ion lithophile elements such as Rb,K,Th,U,Pb,while Ba,Nb,Sr,Ti,etc.show significant negative anomalies;The depletion of Sr may be the result of the separation and crystallization of plagioclase during magma evolution,while the depletion of Ti may be caused by the separation and crystallization of titanium iron oxide,indicating that the magma crystallization differentiation of E-type granite is relatively complete.

关 键 词：岩相学 地球化学 白岗岩 达马拉造山带 纳米比亚湖山铀矿 

分 类 号：P588.121[天文地球—岩石学] P595[天文地球—地质学]