投稿时间：2021-03-11
修订日期：2021-10-21
网络发布日期：2022-01-11
中文摘要:位于幕阜山岩体西南缘的仁里稀有金属矿田是近年来华南地区新发现的一处重要花岗伟晶岩型稀有金属矿产地,铌钽矿体赋存于岩体内外接触带伟晶岩中,具有明显成矿分带性。文章选取仁里矿床岩体内接触带36号伟晶岩脉为研究对象,开展伟晶岩的地球化学及云母Ar-Ar年代学研究,探讨其与花岗岩围岩成因关系及岩体内接触带伟晶岩的成岩成矿时代,以丰富仁里矿田稀有金属成矿作用研究。研究表明,36号伟晶岩具高硅(w(SiO2)为72.87%~76.21%)、高铝(w(Al2O3)为13.69%~15.14%)、低钙镁铁、相对富碱(w(Na2O+K2O)为6.59%~8.33%)、(高钾)钙碱性及过铝质特征;微量元素总体富集Nb、Ta、Hf、U等高场强元素(HFSE),相对亏损Ba、Sr等离子亲石元素(LILE);稀土元素总量(ΣREE)13.95×10-6~71.63×10-6,轻稀土元素富集,重稀土元素亏损,具壳源特征。白云母Ar-Ar坪年龄为早白垩世(136.6±1.4)Ma,成矿作用发生于仁里矿田稀有金属大规模成矿的早阶段。地球化学及矿物学特征显示,36号伟晶岩与花岗岩围岩具有良好的演化关系,结合野外观察现象及成岩年龄,认为36号伟晶岩为花岗质岩浆侵位后残余岩浆结晶分异的产物,母岩为中粗粒片麻状黑云母二长花岗岩。
Abstract:The Renli rare metal ore field located in the southwest margin of Mufushan,is an important newly discovered granite pegmatite type rare metal ore deposit in South China.Niobium and tantalum ore bodies hosted within pegmatite in the contact zone of granite,has obvious metallogenic/metal zoning.In this paper,the No.36 pegmatite vein is selected as the research object,which intruded in the inner contact zone of the granite of the Renli deposit.A detailed lithogeochemical and mica Ar-Ar chronological studies on the pegmatite were carried out to understand its genetic relationship with granite and define the forming ages of pegmatite and rare metal orebodies,and provide more data to enrich the study of rare metal mineralization in Renli ore field.The results show that the No.36 pegmatite is characterized by high silicon (w(SiO2)=72.87%~76.21%),high aluminum (w(Al2O3)=13.69%~15.14%),low calcium,magnesium and iron,relatively rich in alkali (w(Na2O+K2O)=6.59%~8.33%),(high potassium) calc-alkaline and peraluminous.The HFSE (high-field-strength elements) such as Nb,Ta,U and Hf are gene-rally enriched,while the LILE (large-ion-lithophile elements) such as Ba and Sr are relatively depleted.∑REE is 13.95×10-6~71.63×10-6,enriched in LREE and depleted in HREE,indicating the crustal origin.The ArAr plateau age of muscovite is (136.6±1.4)Ma,in the Early Cretaceous.The mineralization occurred in the early stage of large-scale rare metals mineralization in the ore field.Geochemical and mineralogical characteristics show that the No.36 pegmatite has a good evolutionary relationship with granite wall rock,combined with field observation and age dating,we judged that the No.36 pegmatite is the product of crystallization differentiation of residual magma after the granitic magma emplacement,and its parent rock is medium-grained gneissic biotite monzogranite.
keywords:geochemistry mineralization age No.36 pegmatite vein internal connection belt Renli rare metal ore field
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基金项目:湖南省重点领域研发计划项目(编号:2019SK2261)、国家重点研发计划项目(编号:2019YFC0605202)、湖南省自然资源厅科研项目(编号:2018-02)、湖南省地质院科研项目(编号:201921)、湖南省核工业地质局科研项目(编号:KY2018-311-01、KY2019-311-01)、湖南省地勘基金项目(编号:20170331)的联合资助
引用文本：
黄小强,李鹏,张立平,刘翔,黄志飚,柳清琦,李建康,周芳春,苏俊男,曾乐,万海辉,陈虎.2021.湖南仁里稀有金属矿田36号伟晶岩地球化学特征、成矿时代及其意义[J].矿床地质,40(6):1248~1266HUANG Xiao-qiang,LI Peng,ZHANG Li-ping,LIU Xiang,HUANG Zhi-biao,LIU Qing-qi,LI Jian-kang,ZHOU Fang-chun,SU Jun-nan,CENG Le,WAN Hai-hui,CHEN Hu.2021.Geochemical characteristics and metallogenic age of No.36 pegmatite in Renli rare metal ore field, Hunan Province, and their significance[J].Mineral Deposits40(6):1248~1266
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