喜马拉雅琼嘉岗锂辉石伟晶岩结构模型与就位构造机制  

Structural model and emplacement mechanism of the Qiongjiagang spodumene pegmatite,Himalayan

作　　者：李俊瑜 秦克章[1,2] 赵俊兴 赵永能[1,2] 周起凤 曹明坚 朱丽群 何畅通 LI JunYu;QIN KeZhang;ZHAO JunXing;ZHAO YongNeng;ZHOU QiFeng;CAO MingJian;ZHU LiQun;HE ChangTong(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;China Institute of Disaster Prevention,Sanhe 065201,China)

机构地区：[1]岩石圈演化与环境演变全国重点实验室,中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学地球与行星科学学院,北京100049 [3]防灾科技学院,三河065201

出　　处：《岩石学报》2025年第3期751-770,共20页Acta Petrologica Sinica

基　　金：国家重点科技研发计划青年科学家项目(2023YFC2908400);第二次青藏高原科学考察项目(2019QZKK0806);中国科学院先导项目(XDA0430101);中国地质调查项目(DD20240069-07)联合资助.

摘　　要：矿床的就位构造特征对揭示其成因、控矿构造及圈定找矿靶区具有重要指示意义。琼嘉岗锂矿是喜马拉雅地区发现的首个超大型锂矿,具有规模大、品位高的特点,且就位构造特征保存完好。本研究通过宏观、微观及矿物组构分析,获得以下认识:(1)沿藏南拆离系(STDS)北部边界自北向南,帮色曲锂辉石伟晶岩呈透镜状(距STDS北部边界~7.6km,海拔~5312m);琼嘉岗主矿体锂辉石伟晶岩呈厚板状、囊状(距STDS北部边界~16.8km,海拔5364~5500m);琼嘉岗南锂辉石伟晶岩呈平缓的板状(距STDS北部边界~18.7km,海拔5548~5562m)。(2)琼嘉岗主矿体面理中间缓(倾角在10°~23°),两侧陡(倾角在30°~50°),西侧面理倾向在W270°~NW290°,中部面理倾向在SE170°~SW190°,东侧面理倾向在SE130°~SE160°,整体呈“帽子状”就位于肉切村群。(3)琼嘉岗主矿体中靠近围岩的锂辉石线理倾伏向在SE155°~SW190°,倾伏角在17°~40°。锂辉石伟晶岩内部的线理倾伏角在21°~67°,部分线理倾伏向在E90°~SE110°,倾伏角在7°~20°。(4)细晶岩中长石、石英和锂辉石具有一致的颗粒形态优选方位和结晶学优选方位。锂辉石伟晶岩中长石、石英和锂辉石具有一致的颗粒形态优选方位。长石和锂辉石c-<001>轴平行于X轴,而石英c-<0001>轴平行于Z轴。基于以上认识,本研究提出,沿藏南拆离系北部边界向南并随海拔升高,锂辉石伟晶岩呈现出“近端低海拔透镜状-中部囊状或厚板状-远端高海拔平直板状”的就位构造特征。这一认识将为深入研究高喜马拉雅锂辉石伟晶岩的就位特征及寻找新的锂辉石伟晶岩露头提供重要参考,本研究也为全球伟晶岩锂矿的结构模型与就位构造机制提供了典型案例。The emplacement characteristics of the deposit offer crucial insights into its genesis,ore-controlling structures,and delineating exploration targets.The Qiongjiagang lithium orefield,as the first giant lithium orefield in the Himalayas,is characterized by its large scale and high grade,with well-preserved emplacement structural features for the spodumene pegmatite.Insights were gained through macroscopic,microscopic and mineral fabric analyses,including:(1)Along the northern boundary of the South Tibetan Detachment system(STDS)from north to south,the Bangsequ spodumene pegmatite occurs in len s shape(~7.6km from the northern boundary of STDS,elevation of 5312m).The spodumene pegmatite in the main ore body of the Qiongjiagang orefield is thick plate or cyst shaped at the position of~16.8km from the northern boundary of STDS with an elevation of 5364~5500m.The Qiongjiagangnan spodumene pegmatite is plate shaped at~18.7km from the northern boundary of STDS with an elevation of 5548~5562m.(2)The main ore body in Qiongjiagang deposit has a foliation that is gentle in the center(dip angle 10°~23°)and steep on the sides(dip angle 30°~50°).The foliation dip directions range from W270°to NW290°in the western part,SE170°to SW190°in the central part,and SE130°to SE160°in the eastern part,overall forming a“hat-shaped”emplacement in the Rouqiecun Group.(3)The dip direction of spodumene growth lineation near the surrounding rock of the main ore body in Qiongjiagang ranges from SE155°to SW190°,with dip angles between 17°and 40°.Inside the spodumene pegmatite,the dip angles of spodumene growth lineation range from 21°to 67°,with some nearly horizontal.These spodumene lineations construct the spodumene pegmatite emplacement structure model for the main ore body in Qiongjiagang.(4)In aplite,feldspar,quartz and spodumene display consistent preferred grain shapes and crystallographic orientations.In spodumene pegmatite,these minerals maintain consistent grain shape preferred orientations,with feldspar and spodum

关 键 词：藏南拆离系 琼嘉岗锂矿 锂辉石伟晶岩 就位构造 矿物组构 

分 类 号：P585.2[天文地球—岩石学] P588.131[天文地球—地质学]