新疆阿尔泰潜在的中大型铍矿床:以冲乎尔伟晶岩为例  

The potential medium- and large-scale Be ore deposit in Altai,Xinjiang:A case study of pegmatites from Chonghur

作　　者：吕正航[1] 刘堃 张辉[1] 唐勇[1] LV ZhengHang;LIU Kun;ZHANG Hui;TANG Yong(Key Laboratory of High-temperature and High-pressure Study of the Earth s Interior,Institute of Geochemistry,Chinese Academy Sciences,Guiyang 550081,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院地球化学研究所地球内部物质高温高压实验室,贵阳550081 [2]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》2023年第11期3319-3333,共15页Acta Petrologica Sinica

基　　金：国家自然科学基金重点项目(91962222)和面上项目(41873030);2019年贵州省补助资金(GZ2019SIG)联合资助。

摘　　要：锂铍等稀有金属是战略资源,其中,我国的铍资源比锂存在更高的供应风险。新疆阿尔泰是我国最大的伟晶岩省和稀有金属铍资源产地,然而长期开采导致已有矿山闭坑,亟待寻求资源增储。此外,先前对阿尔泰稀有金属资源的勘查、研究和利用主要局限于中阿尔泰地体,而忽略其他地区的资源潜力。笔者通过长期的野外工作,在琼库尔地体冲乎尔地区识别出数条富含绿柱石的伟晶岩,并对其中的典型伟晶岩进行了全岩稀有金属含量、年代学和矿物学等研究,目的在于评价该区伟晶岩的铍成矿潜力。研究结果显示,独居石U-Pb年龄为250.5±3.6Ma,伟晶岩形成于二叠纪末期至三叠纪早期的稀有金属伟晶岩成岩期。伟晶岩中的绿柱石以富Cs、Na和Li等碱金属为特征,且富集程度达到可可托海3号伟晶岩脉绿柱石水平,表明伟晶岩岩浆侵位后经历了高度分异演化。此外,笔者先前研究证实冲乎尔伟晶岩具有与晚三叠世中大型稀有金属矿床一致的同位素组成,表明冲乎尔伟晶岩从物质源区到分异演化条件上都具备成大矿的条件。冲乎尔伟晶岩中Be成矿主要发生在石英-白云母结构带中,其中的BeO品位高达0.321%~0.999%,平均0.590%。初步计算,该伟晶岩的BeO科研储量达中大型规模,考虑到周边同时出露的多条Be矿化伟晶岩,笔者提出冲乎尔萨尔加克伟晶岩具备形成大型Be矿床的潜力。Rare metals such as lithium and beryllium are strategic resources,and the supply risk in beryllium resource is higher than lithium for China.The Altai Orogen,Xinjiang,is the largest pegmatite province and mineral resource base for Be and other rare metals in our country.However,it is urgent to seek increasing reserves of resources because of the closure of many existing mines due to long-term mining and resource exhaustion.Besides,previous exploration,study and utilization of rare metal resources in the Altai Orogen were mainly limited to the Central Altai terrane,while the resource potential in other areas was less concerned.Several beryl-rich pegmatites in Chonghur area in the Qiongkur terrane have been identified by the authors after long term field works,and the typical one was chosen to study on whole rock rare metal content,chronology and mineralogy,aim to evaluate the Be ore-forming potential in pegmatites from the Chonghur area.Results show that monazite grains yield a weighted mean age of 250.5±3.6Ma,indicating the formation of pegmatite in the end of Permian to the Early Triassic coeval with many other rare metal pegmatites in the Chinese Altai.Beryls are rich in alkali metals such as Cs Na and Li,with high enrichment levels equal to the beryl from the Koktokay No.3 pegmatite,indicating a high degree of differentiation and evolution of the pegmatite-forming melt after emplacement.Combined with the consistent isotope composition of the studied pegmatite with the Late Triassic medium-superlarge rare metal ore deposits,the pegmatite is believed to meet the source and differentiation requirements for significant mineralization.Be mineralization was mainly developed in the quartz-muscovite zone of the pegmatite,with high BeO grades of 0.321%~0.999% and average grade of 0.590%.The inferred BeO resource of the pegmatite reach to a medium scale at least after a preliminary calculation.With consideration of other Be-rich pegmatites juxtaposed with the studied pegmatite,a large scale Be ore deposit is expected t

关 键 词：绿柱石 伟晶岩 中大型铍矿床 冲乎尔 阿尔泰 

分 类 号：P588.131[天文地球—岩石学] P597.3[天文地球—地质学] P618.72