阿尔金瓦石峡南稀有金属伟晶岩地球化学、年代学及成矿机制探讨  

Columbite U-Pb age,geochemistry and metallogenic mechanism of rare metal pegmatites from southern Washixia in Altun Region

作　　者：刘艳荣 梁婷[1,2] 王登红[3] 王国庆[1,2] 杨智全 张朋[4] 刘兴忠 陈建中 凤永刚 高景刚 LIU YanRong;LIANG Ting;WANG DengHong;WANG GuoQing;YANG ZhiQuan;ZHANG Peng;LIU XingZhong;CHEN JianZhong;FENG YongGang;GAO JingGang(School of Earth Science and Resources,Chang’an University,Xi’an 710054,Shaanxi,China;The Laboratory ofMineralization and Dynamics,Chang'an University,Xi’an 710054,Shaanxi,China;Institute of Mineral Resource CAGS,Beijing 100037,China;The Third Geological Branch,Xinjiang Geological and Mineral Bureau,Korla 841000,Xinjiang,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]长安大学成矿作用及成矿动力学实验室,陕西西安710054 [3]中国地质科学院矿产资源研究所,北京100037 [4]新疆维吾尔自治区质矿产勘查开发局第三地质大队,新疆库尔勒841000

出　　处：《矿床地质》2025年第1期124-142,共19页Mineral Deposits

基　　金：国家重点研发计划“战略性矿产资源开发利用”专项“我国西部伟晶岩型锂等稀有金属成矿规律与勘查技术”项目(编号:2021YFC2901902);中国地质调查局“中国矿产地质志”项目(编号:DD20221695);陕西省自然科学基础研究计划项目(编号:2022JM-158)联合资助。

摘　　要：新疆阿尔金地区瓦石峡南锂铍矿是近年来新发现的一个大型花岗伟晶岩型稀有金属矿床。为了揭示含矿伟晶岩脉的年龄、地球动力学背景和成矿机制,文章以ρ3号锂辉石伟晶岩脉和ρ9号锂云母伟晶岩脉为研究对象,开展了全岩地球化学和铌钽铁矿U-Pb年代学研究。结果显示,锂辉石花岗伟晶岩和锂云母花岗伟晶岩的铌钽铁矿U-Pb年龄分别为(450.6±5.6)Ma和(413.2±4.9)Ma。结合区域研究成果,笔者认为矿区存在2期稀有金属成矿作用,前者可能形成于挤压碰撞向碰撞后伸展转换阶段,而后者形成于伸展阶段。2类伟晶岩均具有高硅(68.22%~75.09%)、高铝(15.62%~17.19%)、低钙(0.62%~2.04%)和相对富碱(4.06%~7.90%)的特征。地球化学特征显示,二者分异演化程度均较高,且具一定成因联系,推测应为花岗质岩浆脉动式多期次上涌并发生高度分异而形成。The southern Washixia is a newly discovered large-sized granitic pegmatite type rare metal(lithium-berylium)deposit in the Altun region,Xinjiang.In order to reveal the metallogenic mechanism,age,and geodynamic background of the ore-bearing pegmatite dikes at the southern Washixia,in this contribution,we focused on two representative pegmatite dikes(namely theρ3 spodumene pegmatite and theρ9 lepidolite pegmatite dikes),and investigated their whole-rock geochemistry and columbite U-Pb geochronology.The columbite U-Pb ages of the spodumene granitic pegmatite and lepidolite granitic pegmatite are(450.6±5.6)Ma and(413.2±4.9)Ma,respectively,which shows that there exist two stages of metallogenesis of rare metals in the southern Washixia area.Combined with regional tectonic evolution,the age data suggest that the spodumene pegmatite may have formed during the transition stage from compressive collision to extension,whereas the lepidolite pegmatite may have formed at the extensional stage.Spodumene granitic pegmatite and lepidolite granitic pegmatite are both characterized by high SiO2(68.22%~75.09%),high Al2O3(15.62%~17.19%),low CaO(0.62%~2.04%),and relative alkali enrichment(4.06%~7.90%).The high differentiation index(DI=85.44~94.34),mineralogical and geochemical characteristics of the samples all indicate that the two pegmatites,closely related to each other,are formed by multi-stage upwelling of granitic magma and highly crystallization differentiation.

关 键 词：花岗伟晶岩 地球化学 铌钽铁矿U-Pb定年 瓦石峡南 阿尔金 

分 类 号：P618.31[天文地球—矿床学] P618.79[天文地球—地质学] P618.86