摘要
近年来,喜马拉雅稀有金属勘查与研究工作已取得许多突破,然而已发现的锂矿和锂矿化点集中于喜马拉雅东段与中段,对喜马拉雅西段锂等稀有金属的资源潜力尚不清楚。本文报道了喜马拉雅西段翁波穹隆中新发现的锂辉石伟晶岩,其中的稀有金属矿物包括锂辉石、透锂长石、锂蓝闪石、锂霞石、绿柱石、锡石、铌钽铁矿,全岩Li含量范围是1426×10^(-6)~27300×10^(-6),换算为Li 2O最高含量达5.88%,同时Rb(71.9×10^(-6)~1542×10^(-6))、Cs(64.9×10^(-6)~302×10^(-6))、Be(51.4×10^(-6)~195×10^(-6))和Sn(60.1×10^(-6)~196×10^(-6))等稀有金属含量也较高。翁波锂辉石伟晶岩具有极低的K 2O/Na 2O(0.06~1.49)、Nb/Ta(1.82~3.84)和Zr/Hf比值(2.65~9.43)以及低的总稀土含量(∑REE=0.13×10^(-6)~3.59×10^(-6)),较高的Rb/Sr比值(3.31~70.53),表明其经历了强烈的结晶分异作用。锡石U-Pb同位素定年结果表明,锂辉石伟晶岩的形成时代为16~15Ma。结合矿物特征、地球化学特征、形成时代和区域构造演化历史,本文认为翁波锂辉石伟晶岩的形成与喜马拉雅新生代平行造山带的伸展过程密切相关,并经历了岩浆结晶作用、熔流体相互作用与热液交代作用多阶段演化过程。翁波穹隆锂辉石伟晶岩是喜马拉雅西段特提斯喜马拉雅穹隆中首次发现的锂矿化点,也是目前在我国境内喜马拉雅造山带最西部的锂矿化点。这一发现展现了该区具有良好的稀有金属成矿潜力,极大地延伸了喜马拉雅锂成矿带的范围,反映出喜马拉雅造山带不同区域锂成矿机制的差异,表明南北向裂谷及特提斯喜马拉雅穹隆中的淡色花岗岩演化及稀有金属成矿作用值得多加关注,为今后喜马拉雅锂资源提供了新的勘查方向。
In recent years,significant breakthroughs have been made in the exploration and research of rare-metal deposits in the Himalayan region.However,the discovered lithium deposits and lithium mineralization sites are mainly concentrated in the eastern and central segments of the Himalayas,while the resource potential of lithium and other rare metals in the western Himalayas remains unclear.This paper reports new discovery of spodumene-bearing pegmatite in Wengbo dome.The rare metal mineral assemblage includes spodumene,petalite,holmquistite,eucryptite,beryl,cassiterite,columbite-tantalite.The geochemical analysis of whole-rock samples indicates that the lithium contents of the spodumene-bearing pegmatites range from 1426×10^(-6)to 27300×10^(-6),with the highest Li 2O consent reaching 5.88%.Additionally,the samples exhibit elevated concents of rare metals such as Rb(71.9×10^(-6)~1542×10^(-6)),Cs(64.9×10^(-6)~302×10^(-6)),Be(51.4×10^(-6)~195×10^(-6)),and Sn(60.1×10^(-6)~196×10^(-6)).The Wengbo spodumene-bearing pegmatites are characterized by extremely low geochemical ratios,including K 2O/Na 2O(0.06~1.49),Nb/Ta(1.82~3.84),Zr/Hf(2.65~9.43),and low total rare earth element contents(∑REE=0.13×10^(-6)~3.59×10^(-6)),coupled with high Rb/Sr ratios(3.31~70.53).These features indicate intense fractional crystallization.The U-Pb isotope dating of cassiterite shows that the age of the spodumene-bearing pegmatite is 16~15Ma.Based on the mineral characteristics,geochemical signatures,formation age,and regional tectonic evolution history,we suggest that the formation of the Wengbo spodumene-bearing pegmatites is closely related to the Cenozoic orogen-parallel extension process in the Himalayan orogenic belt,and the pegmatites underwent stages from magmatic crystallization to late-stage melt-fluid interactions and hydrothermal alteration during magmatic evolution.The Wengbo spodumene-bearing pegmatites represent the first discovery of lithium mineralization in Tethyan Himalayan domes in the western Himalayas,and currently constitute the westernmost lithium mineralization found in the Himalayan orogenic belt in China.This discovery shows that the area has important potential for rare metal mineralization,greatly extending the scope of the Himalayan lithium mineralization belt,and reflects the differences in the lithium mineralization in different regions of the Himalayan orogenic belt,indicating that the evolution of leucogranites and rare metal mineralization in the north-south trending rift and the Tethyan Himalayan domes are worthy of more attention,and providing a new direction for the investigate of lithium resources in the Himalaya in the future.
作者
邢璐遥
刘小驰
李雪震
赵向英
胡方泱
杨浩
吴福元
XING LuYao;LIU XiaoChi;LI XueZhen;ZHAO XiangYing;HU FangYang;YANG Hao;WU FuYuan(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;College of Earth Sciences,Jilin University,Changchun 130061,China)
出处
《岩石学报》
北大核心
2025年第9期2982-2999,共18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)联合资助。
关键词
稀有金属
喜马拉雅西段
翁波穹隆
锂辉石伟晶岩
淡色花岗岩
南北向裂谷
藏南拆离系
Rare-metal elements
Western Himalaya
Wengbo dome
Spodumene-bearing pegmatite
Leucogranite
North-south trending rift
South Tibetan Detachment System
