西藏康马锂辉石伟晶岩的发现与特提斯喜马拉雅锂资源前景  

Discovery of spodumene pegmatites in the Kangmar,Xizang and the lithium resource prospects in the Tethyan Himalaya

作　　者：次仁顿珠 刘小驰[2] 毛国正 刘成林 吴魏 赵向英 邢璐遥 胡方泱 赵俊兴[2] 李俊瑜 多吉 吴福元[2,3] CIREN DunZhu;LIU XiaoChi;MAO GuoZheng;LIU ChengLin;WU Wei;ZHAO XiangYing;XING LuYao;HU FangYang;ZHAO JunXing;LI JunYu;DOR Ji;WU FuYuan(Tibet Engineering Exploration and Construction(Group)Co.,Ltd.,Lhasa 850000,China;State Key Laboratory of Lithospheric and Environmental Coevolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Tibet Bureau of Geology and Mineral Exploration and Development,Lhasa 850000,China)

机构地区：[1]西藏工程勘察施工(集团)有限公司,拉萨850000 [2]中国科学院地质与地球物理研究所,岩石圈演化与环境演变全国重点实验室,北京100029 [3]中国科学院大学地球与行星科学学院,北京100049 [4]西藏地质矿产勘查开发局,拉萨850000

出　　处：《岩石学报》2025年第4期1121-1134,共14页Acta Petrologica Sinica

基　　金：中国科学院战略性先导科技专项(XDA0430101);第二次青藏高原综合科学考察研究(2019QZKK0802、2022QZKK0203);西藏地勘局局管地勘项目(藏地勘办发2024-3)联合资助.

摘　　要：本研究报道了喜马拉雅造山带康马穹隆新发现的锂辉石伟晶岩,这是首次在特提斯喜马拉雅穹隆内识别出富锂矿物伟晶岩。该伟晶岩呈岩脉状集中侵位于康马穹隆西南部韧性剪切带中,围岩为二叠统白定浦组厚层大理岩化灰岩。锂辉石伟晶岩中出现的稀有金属矿物包括锂辉石、透锂长石、锡石、天河石、绿柱石、铌铁矿族矿物、褐钇铌矿、铌铁金红石和烧绿石等。全岩地球化学分析结果显示,锂辉石伟晶岩样品锂含量范围是28.7×10^(-6)~15251×10^(-6),对应Li_(2)O含量最高为2.64%,已达到工业品位;此外,Rb、Nb等稀有金属元素也具有较高的含量(Rb=176×10^(-6)~2528×10^(-6)、Nb=22.4~145×10^(-6))。相对喜马拉雅其他区域发现的锂辉石伟晶岩,康马锂辉石伟晶岩具有富集重稀土特征((La/Yb)_(N)=0.11~0.75),并显示出较高的Nb/Ta(3.65~8.84)、Zr/Hf(9.68~14.9)比值以及更为显著的负铕异常(Eu/Eu^(*)=0.003~0.05)。独居石原位U-Th-Pb定年结果表明,锂辉石伟晶岩形成于晚渐新世-早中新世(26~22Ma),与出露于康马穹隆核部的绿柱石伟晶岩脉侵入时代(25Ma)相一致。本文提出康马穹隆存在新生代岩浆作用,锂辉石伟晶岩是淡色花岗岩岩浆强烈结晶分异作用的产物,其形成与穹隆拆离断层系统密切相关。康马锂辉石伟晶岩的发现揭示出特提斯喜马拉雅穹隆内具有良好锂成矿前景,穹隆周边韧性剪切带应是进一步稀有金属勘查的重点层位。The discovery of spodumene-bearing pegmatite in the Kangmar dome of the Himalayan orogen represents the first identification of lithium-rich pegmatites within the Tethyan Himalayan dome.These pegmatite dikes are predominantly located in the ductile shear zone in the southwestern part of the Kangmar dome,with the surrounding rocks of the thick-bedded marbleized limestone of the Permian Badingpu Formation.The main rare-metal minerals include spodumene,petalite,cassiterite,amazonite,beryl,columbite-tantalite,fergusonite,niobium rutile,and pyrochlorite.The geochemical analysis of whole-rock samples indicates that the lithium concentrations in the spodumene pegmatite samples ranges from 28.7×10^(-6) to 15251×10^(-6),with the highest Li_(2)O content reaching 2.64%,which meets the industrial grade.Additionally,rare-metal elements such as Rb and Nb concentrations are also relatively high.Compared with spodumene pegmatites discovered in other regions of the Himalayan orogen,the Kangmar spodumene pegmatites are characterized by enrichment of heavy rare earth elements((La/Yb)_(N)=0.11~0.75),higher Nb/Ta(3.65~8.84)and Zr/Hf(9.68~14.9)ratios,and a more pronounced negative europium anomaly(Eu/Eu^(*)=0.003~0.05).In-situ U-Th-Pb dating of monazite reveals that the spodumene pegmatites primarily formed during the Late Oligocene to Early Miocene(26~22Ma),which is consistent with the intrusion age of the beryl pegmatite dikes exposed in the core of the Kangmar dome(25Ma).This study suggests that there was Cenozoic magmatic activity in the Kangmar dome,and the spodumene pegmatites are product of intense fractionation of the leucogranite magmas.The discovery of the Kangmar spodumene pegmatites indicate promising lithium mineralization potential within the Tethyan Himalayan dome,and the ductile shear zones surrounding the dome should be the focus of further exploration for rare metal minerals.

关 键 词：康马穹隆 藏南拆离系 渐新世 稀有金属 锂辉石伟晶岩 淡色花岗岩 

分 类 号：P588.131[天文地球—岩石学] P597.3[天文地球—地质学] P618.71