摘要
喜马拉雅淡色花岗岩具有较好的稀有金属成矿前景。珠穆朗玛峰位于该淡色花岗岩带的中部,其中大量的淡色花岗岩和伟晶岩出露,并成为珠穆朗玛重要的岩石组成部分。近期,我们在珠峰前进沟地区发现并采集了锂成矿伟晶岩,在手标本上可以清晰看到浅褐红色的铁锂云母。进一步的全岩地球化学以及矿物学研究表明,前进沟锂成矿伟晶岩为锂电气石-锂云母型伟晶岩,具有稀有金属元素(Be-Nb-Li)含量高、Rb/Sr比值高、Zr/Hf和Nb/Ta比值低等特征。所有的矿物学和地球化学特征都表明该伟晶岩经历了高度的岩浆分异作用。矿物成分上看,云母由铁锂云母演变为锂云母,电气石由黑电气石演变为锂电气石,Fe、Mg含量降低,Li含量升高,这一特征直接指示着演化过程中岩浆成分的变化。这次发现,是首次在该地区发现锂成矿作用,也是我国喜马拉雅首次报道锂电气石-锂云母型伟晶岩的存在。结合珠穆朗玛峰周围(普士拉、热曲)近期发现的锂辉石-透锂长石型伟晶岩,珠穆朗玛地区很可能成为我国重要的一个锂(Li)成矿远景区。
The Himalaya leucogranite belt is evaluated as a prospect for rare-metal mineralization.The Mount Qomolangma is located in the middle part of this leucogranite belt,where a large number of leucogranites and pegmatites occurred as the important components of the Qomolangma orogenic area.Recently,Li-mineralized pegmatites have been recognized and sampled in Hermit Gorge where the light brown red zinnwaldite can be clearly identified in the pegmatite specimens.Further geochemistry and mineralogy study show that these Li mineralized pegmatites have been identified as the elbaite-lepidolite subtype,which are characterized with high contents of rare-metal elements(Be-Nb-Li),high Rb/Sr ratio,and low Zr/Hf and Nb/Ta ratios.All the mineralogical and geochemical features indicate that these pegmatites have experienced a high degree of magma fractionation.In terms of mineral chemistry,micas have evolved from zinnwaldite to lepidolite,and tourmalines from schorl to elbaite,and the contents of Fe and Mg in them decreased,while the Li content increased,which is indicative of the evolution process of magma.It is the first found Li mineralization in the Qomolangma area,and the striking first report of the occurrence of elbaite-lepidolite subtype pegmatite in Himalaya.Combined with the recent researches of spodumene-petalite subtype pegmatites around Mount Qomolangma(Pusila,Rachu),the Qomolangma region is probably a crucial Li mineralization prospect in China.
作者
刘晨
王汝成
吴福元
谢磊
刘小驰
LIU Chen;WANG RuCheng;WU FuYuan;XIE Lei;LIU XiaoChi(State Key Laboratory for Mineral Deposits Research,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China;State Key Laboratory of Lithospheric Evolution,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)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第11期3287-3294,I0001-I0006,共14页
Acta Petrologica Sinica
基金
国家自然科学基金项目(91855209)
第二次青藏高原综合科学考察研究(2019QZKK0802)联合资助
