Cesium-rubidium mineralization in Himalayan leucogranites  

作　　者：Fangyang HU Xiaochi LIU Shaoxiong HE Jiamin WANG Fuyuan WU 

机构地区：[1]Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 00029,China [3]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Science China Earth Sciences》2023年第12期2827-2852,共26页中国科学（地球科学英文版）

基　　金：supported by the Second Tibetan Plateau Scientific Expedition and Research (Grant Nos.2022QZKK0203,2019QZKK0802);the National Natural Science Foundation of China (Grant Nos.91755000,41888101,41902055)。

摘　　要：This paper presents a study of a newly discovered pollucite-lepidolite-albite granite(PLAG)in the Himalayan leucogranite belt,which marks the first occurrence of pollucite,a major cesium silicate mineral,in the Himalayan orogenic belt(China).The rock appears at the northern part of the Gyirong pluton,coexisting with the tourmaline-bearing two-mica granite(TMG).Primary rare-metal minerals include lepidolite(Li),spodumene(Li),pollucite(Cs),cassiterite(Sn),and microlite(Ta).Micas,mainly lithian muscovite to lepidolite,contain 4.07 wt.%Li_2O and 0.76 wt.%Rb_2O on average.The average Li_2O content of the spodumene is 7.95 wt.%.Pollucite not only has an average Cs_2O content of 34 wt.%,but also has an elevated Rb_2O content of about 0.16 wt.%.Notably,this granite attains industrial grades for rare metals,specifically with Li_2O,Rb_2O,and Cs_2O contents of 0.49–1.19 wt.%,0.12–0.24 wt.%,and 0.69–2.33 wt.%,respectively.Dating results of magmatic accessory cassiterite and monazite indicated that the PLAG was formed at 19–18 Ma,slightly later than the TMG(22–20 Ma)of the Gyirong pluton.Thus,these two types of granites may form within the same magmatic system considering their pulsating intrusive contact,formation ages,and whole-rock and mineral chemical compositions.Furthermore,the abundant presence of pollucite suggests that the PLAG experienced high degrees of magmatic fractionation.In comparison to the Pusila spodumene pegmatite in the Himalaya and the Yashan topaz-lepidolite granite in Jiangxi,South China,the Gyirong PLAG exhibits different whole-rock and mineral compositions,resulting from differences in source materials and fractionation processes.Notably,the difference in fluorine(F)content may determine the degree of rare-metal element enrichment.The discovery of Gyirong PLAG highlights multiple stages and types of rare-metal mineralization in the Himalayan leucogranite belt,which is controlled by the South Tibetan Detachment System.The Cs-bearing geyserite deposit exposed along the Yarlung-Zangbo River,to

关 键 词：HIMALAYA Pollucite LEPIDOLITE LEUCOGRANITE Rare-metal elements 

分 类 号：P618.84[天文地球—矿床学] P618.77[天文地球—地质学]