喜马拉雅吉隆花岗伟晶岩中锂矿物的研究  

The study of Li-minerals in granitic pegmatites from Gyirong,Himalaya

作　　者：田恩农 谢磊[1] 王汝成[1] 吴福元[4,5] TIAN EnNong;XIE Lei;WANG RuCheng;WU FuYuan(State Key Laboratory for Mineral Deposits Research,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China;Hebei Key Laboratory of Green Development of Rock and Mineral Materials,School of Gemology and Materials Science,Hebei GEO University,Shijiazhuang 050031,China;Hebei Province Collaborative Innovation Center for Strategic Critical Mineral Research,Shijiazhuang 050031,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)

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室,南京大学地球科学与工程学院,南京210023 [2]河北地质大学,河北省岩石矿物材料绿色开发重点实验室,宝石与材料学院,石家庄050031 [3]河北省战略性关键矿产研究协同创新中心,石家庄050031 [4]中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京100029 [5]中国科学院大学地球与行星科学学院,北京100049

出　　处：《岩石学报》2024年第2期484-498,共15页Acta Petrologica Sinica

基　　金：第二次青藏高原综合科学考察研究(2019QZKK0802);国家自然科学基金项目(42222202、91855209);中央高校基本科研业务费专项资金(020614380173);河北省教育厅科学研究项目(BJK2024180)联合资助。

摘　　要：喜马拉雅造山带中部的吉隆岩体出露有大量淡色花岗岩和花岗质伟晶岩,已有文献报道该岩体英雄沟和扎龙沟淡色花岗岩和伟晶岩中有铁锂云母、锂云母、锂辉石等锂矿物产出。本次研究对吉隆岩体北部扎龙沟的伟晶岩进行了岩相学和矿物学研究,厘定了锂辉石伟晶岩和锂云母-锂电气石伟晶岩(含细晶岩)两种类型的富锂伟晶岩。研究结果显示,在锂辉石伟晶岩中主要的富锂矿物除了已知的锂辉石和锂云母,还发现了透锂长石,同时锂云母的边部出现的铯锂云母((Cs,K)Li_(2)Al[Si_(4)O_(10)]F_(2),Cs/(Cs+K)原子比>0.5)中Cs_(2)O含量达16.9%,该矿物首次在喜马拉雅发现,推测是由锂云母与后期富Cs流体作用后形成。在锂云母-锂电气石细晶岩中主要的富锂矿物包括锂云母和锂电气石,锂云母中的Li_(2)O含量为0.9%~6.7%;锂电气石中Li_(2)O含量最高可达2.4%,且FeO、MgO和CaO含量较低(分别<1.1%、<0.01%和<2.6%),接近锂电气石端元成分。结合吉隆扎龙沟含锂伟晶岩中大量产出铯沸石和细晶石,确认这些伟晶岩是典型的LCT(Li-Cs-Ta)型伟晶岩,矿物组成和成分显示它们具有极高的分异演化程度。Massive leucogranites and granitic pegmatites were exposed in the Gyirong region,the middle of Himalayan orogen.Recent studies reported that the Li minerals,such as zinnwaldite,lepidolite and spodumene,were found in the leucogranites and granitic pegmatites from the Yingxionggou and Tsalung district in Gyriong pluton.In this study,two-type lithium-rich pegmatites from the Tsalung district were identified by the detailed petrographic and mineralogical studies,including spodumene pegmatite and lepidolite-elbaite pegmatite(aplite included).The major Li-rich minerals in spodumene pegmatites are spodumene,lepidolite and petalite which is new-found in this study.Especially,sokolovaite((Cs,K)Li_(2)Al[Si_(4)O_(10)]F_(2),Cs/(Cs+K)atomic ratio>0.5),Cs-analogue lepidolite,is firstly discovered in the Himalayan orogen,with the marginal occurrence adjacent to the lepidolite and Cs_(2)O content up to 16.9%.It is suggested that sokolovaite is the product of lepidolite reacting with late Cs-rich fluids by the mineral texture.In the lepidolite-elbaite aplite,the main Li-rich minerals include lepidolite and elbaite.Lepidolite contains 0.9%~6.7%Li_(2)O content.Tourmaline contains Li_(2)O content up to 2.4%,and low FeO,MgO,and CaO contents(<1.1%,<0.01%and 2.6%,respectively),close to the end-member of elbaite.Combined with abundant pollucite and microlite found in the Tsalung Li-mineralized pegmatites in Gyirong pluton,it is confirmed that the Tsalung pegmatite is typical LCT(Li-Cs-Ta)-type pegmatite,and the mineral constitution and their chemical compositions demonstrate that the pegmatite is extremely high-evolved.

关 键 词：花岗质伟晶岩 细晶岩 富铯锂云母 铯锂云母 锂电气石 

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