初论高温花岗岩-伟晶岩锂铍成矿系统:以阿尔金中段地区为例  

Concept of high-temperature granitepegmatite Li-Be metallogenic system with a primary study in the middle Altyn-Tagh

作　　者：徐兴旺[1,2,3] 洪涛 李杭 牛磊 柯强[1,2,3] 陈建中 刘善科 翟明国[1,2,3] XU XingWang;HONG Tao;LI Hang;NIU Lei;KE Qiang;CHEN JianZhong;LIU ShanKe;ZHAI MingGuo(Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;Guangdong Provincial Key Lab of Geodynamics and Geohazards,School of Earth Sciences and Engineering,Sun Yat-Sen University,Guangzhou 510275,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519000,China;No.3 Geological Party,Xinjiang Bureau of Geology and Mineral Exploration and Development,Kuerle 841000,China)

机构地区：[1]中国科学院地质与地球物理研究所中国科学院矿产资源研究重点实验室,北京100029 [2]中国科学院地球科学研究院,北京100029 [3]中国科学院大学,北京100049 [4]中山大学地球科学与工程学院广东省地球动力作用与地质灾害重点实验室,广州510275 [5]南方海洋科学与工程广东省实验室(珠海),珠海519000 [6]新疆地矿局第三地质大队,库尔勒841000

出　　处：《岩石学报》2020年第12期3572-3592,共21页Acta Petrologica Sinica

基　　金：中国科学院地质与地球物理研究所重点部署项目(IGGCAS-201902);中国科学院重点部署项目(ZDRW-ZS-2020-4-3);第二次青藏高原综合科学考察研究(2019QZKK0802)联合资助。

摘　　要：花岗岩-伟晶岩型锂铍矿床是锂铍矿床的重要类型。关于锂铍金属在源区花岗质岩浆形成过程的富集机制,岩石学家和矿床学家多强调锂铍花岗岩-伟晶岩的母花岗岩(淡色花岗岩)源于变沉积岩的白云母熔融,但实验岩石学显示白云母熔融其熔体量小(<10vol%)、熔体从岩石中提取锂铍的效率低。这意味着白云母熔融形成花岗质岩浆过程锂铍金属富集机制可能不是花岗质岩浆获取锂铍的主要机制。基于黑云母熔融可以获得大体积熔体(可达50vol%)的实验结果,指出变杂砂岩(黑云母片麻岩)与含黑云母的英云闪长质片麻岩部分熔融形成的黑云母花岗质高温岩浆(>800℃)其结晶形成黑云母花岗岩并可分异演化为淡色花岗岩与锂铍花岗岩-伟晶岩、并构成高温花岗岩-伟晶岩锂铍成矿系统,是花岗岩-伟晶岩型锂铍矿床形成的重要成矿系统,其特征与形成机制值得进一步研究。黑云母脱水熔融过程残留相没有富含锂铍矿物的形成,新形成的花岗质岩浆可以高效地从源岩中获取锂铍金属,是一种新的锂铍富集机制。研究团队于2018年率先进入阿尔金中段无人区开展稀有金属成矿作用的地质调查与考察。经过两年的野外地质调查,新发现2个中-大型花岗伟晶岩型锂铍矿(吐格曼铍锂矿与吐格曼北锂铍矿)和塔什萨依金绿宝石矿,发现大量的黑云母花岗岩、二云母花岗岩与伟晶岩,指出这些淡色花岗岩与伟晶岩成因于黑云母花岗岩的分异演化并构成高温花岗岩-伟晶岩锂铍成矿系统,初步构建花岗岩-伟晶岩锂铍成矿系统的3种组构类型,初步揭示吐格曼铍锂矿与吐格曼北锂铍矿形成于468~460Ma,为加里东期锂铍伟晶岩区。阿尔金中段高温花岗岩-伟晶岩系统成矿特征显示:1)高温黑云母花岗质岩浆可以通过连续的分异结晶形成从下往上依次分带、垂向叠置的系统(组构A),即从黑云母花岗岩�The lithium-beryllium metals are the"critical"metals of national strategy and the national demand of the new lithiumberyllium reserve is increasing.The lithium-beryllium(Li-Be)granitic pegmatite deposit is one of the important types of Li-Be deposits.It was generally suggested that melting of muscovite of metasedimentary rocks produces granitic melts,the parental magma of the Li-Be granitic pegmatite.However,the experimental investigation results show that the melting of muscovite produces low amount(<10%by volume)of melts with low efficiency of extracting Li-Be.This indicates that the enrichment of Li-Be during the melting of the muscovite to form the leucogranite may not be the main mechanism for the formation of granitic magma and the accumulation of LiBe metals.On the basis that dehydration melting of the biotite would produce more than 50%(by volume)melts,it is suggested that the melting of biotite from the metagraywacke(biotite gneiss)and biotite-bearing tonalite gneiss might generate the high-temperature(>800℃)biotite granitic magma,which may evolve into leucogranite and Li-Be granitic pegmatite to form a high-temperature granitepegmatite Li-Be metallogenic system,as an important part of granite-pegmatite Li-Be metallogenic systems.The residual phase of the dehydrating and melting process of biotite is not rich in Li-Be minerals,thus,the evolved granitic magma might efficiently obtain Li-Be metals from the source rock,which might be a new enrichment mechanism for Li-Be metals.The middle Altyn-Tagh is a depopulated zone and a blank area for the prospecting of Li-Be metal mineralization research.Our research group has taken the lead in the geological survey and investigation of rare metal mineralization in the middle Altyn-Tagh since 2018.After two years of field investigation,two medium-large Li-Be granitic pegmatite deposits(Tugman Li-Be and Tugman North Li-Be deposits)and Tashisayi chrysoberyl deposit have been discovered,which have close genetic relationships with biotite granite,two-mica granite,and p

关 键 词：高温 花岗岩-伟晶岩 锂铍矿床 成矿系统 阿尔金中段 

分 类 号：P618.71[天文地球—矿床学] P618.72[天文地球—地质学]