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| 川西九龙打枪沟锂铍矿床赋矿伟晶岩矿物学和矿物化学特征 |
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胡军亮1,2, 谭洪旗1,3,4, 周雄1,3,4, 倪志耀2, 周玉1,3,4
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1.中国地质科学院矿产综合利用研究所, 四川 成都 610041;2.成都理工大学, 四川 成都 610059;3.中国地质调查局稀土资源应用技术创新中心, 四川 成都 610041;4.中国地质调查局金属矿产资源综合利用技术研究中心, 四川 成都 610041
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| 摘要: |
| 打枪沟伟晶岩型锂铍矿床是九龙地区典型的中型锂铍矿床，是松潘-甘孜锂成矿带的重要组成部分。该矿床含矿伟晶岩主要为钠长石伟晶岩和钠长石-锂辉石伟晶岩，主要矿石矿物为锂辉石和绿柱石。在翔实的野外地质调查的基础上，选取打枪沟锂铍矿床典型矿脉（ⅠLi，Be和ⅡBe矿脉）开展岩相学、矿物学和矿物化学研究，以揭示其矿物生成顺序和成矿阶段。电子探针分析结果显示，含锂矿物主要为锂辉石，矿物中Li2O含量为7.94%~8.29%，平均为8.12%；云母类矿物为白云母和锂-多硅白云母，白云母中Li2O含量为0.08%~0.35%，平均为0.21%，Rb2O含量为0.13%~0.35%，平均为0.24%，锂-多硅白云母中Li2O含量为1.11%~1.43%，平均为1.28%，Rb2O含量为0.79%~0.94%，平均为0.87%；电气石为铁电气石-锂电气石系列，Li2O含量为0.48%~0.85%，平均为0.64%。在详细的矿物显微特征研究并结合电子探针分析的基础上，分析认为伟晶岩中稀有金属矿物由绿柱石→绿柱石+锂辉石→锂辉石→锂辉石+锂-多硅白云母转变，云母由白云母向锂-多硅白云母转变，电气石由铁电气石向锂电气石过渡，长石矿物由微斜长石+钠长石→钠长石→交代钠长石转变，石英由原生石英→后期热液石英变化。综合分析认为，打枪沟锂铍矿床经历了多阶段的演化过程，主要划分为结晶分异阶段、交代阶段、热液阶段，其中锂铍等稀有金属矿物的形成主要发生在结晶分异阶段和交代阶段。 |
| 关键词: 矿物化学 锂铍矿床 伟晶岩 打枪沟 九龙 四川 |
| DOI： |
| 分类号:P57;P618.7 |
| 基金项目:中国地质调查局项目《四川九龙—可尔因地区大型锂资源基地综合调查评价》（编号：DD20190185） |
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| A study of mineralogy and mineral chemistry of ore-bearing pegmatites in the Daqianggou lithium-beryllium deposit,western Sichuan |
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HU Junliang1,2, TAN Hongqi1,3,4, ZHOU Xiong1,3,4, NI Zhiyao2, ZHOU Yu1,3,4
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1.Institute of Multipurpose Utilization of Mineral Resources, CAGS, Chengdu 610041, Sichuan, China;2.Chengdu University of Technology, Chengdu 610059, Sichuan, China;3.Technical Innovation Center of Rare Earth Resources, China Geological Survey, Chengdu 610041, Sichuan, China;4.Research Center of Multipurpose Utilization of Metal Mineral Resources of China Geological Survey, Chengdu 610041, Sichuan, China
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| Abstract: |
| The Daqianggou pegmatite type lithium-beryllium deposit is a typical medium-sized lithium-beryllium deposit in Jiulong area.Its geotectonic location is located in the Yajiang residual basin on the southern margin of the Songpan-Garze fold belt,and the deposit is an important part of the Songpan-Garze lithium metallogenic belt.The main types of ore-bearing pegmatites in the Daqianggou deposit can be divided into albite type and albite-spodumene type,and the main ore minerals are spodumene and beryl.In this paper,based on the field geological survey work,the authors chose typical veins (ⅠLi,Be and ⅡBe) in the Daqianggou lithium beryllium deposit to conduct studies of facieology,mineralogy and mineral chemistry in order to reveal the sequence order of mineral formation and ore-forming stages.The results of electron microprobe analysis show that the lithium-containing mineral is mainly spodumene.The content of Li2O in spodumene is 7.94%~8.29%,averaging 8.12%.Mica minerals are muscovite and lithium-rich phengite.The content of Li2O in muscovite is 0.08%~0.35%,averaging 0.21%,and the content of Rb2O is 0.13%~0.35%,averaging 0.24%.The Li2O content in lithium-rich phengite is 1.11%~1.43%,averaging 1.28%,and the Rb2O content is 0.79%~0.94%,averaging 0.87%.Tourmaline belongs to an iron tourmaline-lithium tourmaline series,with Li2O content of 0.48%~0.85%,averaging 0.64%.Based on the detailed study of the microscopic characteristics of minerals combined with electron microprobe analysis,the authors hold that the rare metal mineral changes in pegmatite are in order of beryl → beryl + spodumene → spodumene → spodumene + lithium-rich phengite,mica changes from muscovite to lithium-rich phengite,tourmaline transition from iron tourmaline to lithium tourmaline,feldspar mineral is composed of micro-plagioclase + albite → albite → metasodium albite,and quartz changes from primary quartz to late hydrothermal quartz.Finally,a comprehensive analysis suggests that the metallogenic stages of the Daqianggou lithium-beryllium deposit underwent a multi-stage evolution process,which could be mainly divided into crystallization stage,metasomatic stage and hydrothermal stage.The formation of rare metal minerals such as lithium and beryllium minerals mainly occurred in the crystallization stage and metasomatic stage. |
| Key words: mineral chemistry lithium-beryllium deposit pegmatite Daqianggou Jiulong Sichuan Province |