广西上林合山组炭质泥岩中锂和稀土元素的成因及富集机制  

Origin and enrichment mechanism of lithium and rare earth elements incarbonaceous mudstone of Heshan Formation,Shanglin,Guangxi

作　　者：曹泊 秦云虎 朱士飞[1] 傅雪海[2] 徐辉 宗师 CAO Bo;QIN Yunhu;ZHU Shifei;FU Xuehai;XU Hui;ZONG Shi(Jiangsu Mineral Resources and Geological Design and Research Institute,Xuzhou 221006,China;School of Resources and Geosciences,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]江苏地质矿产设计研究院,江苏徐州221006 [2]中国矿业大学资源与地球科学学院,江苏徐州221116

出　　处：《煤炭学报》2022年第5期1851-1864,共14页Journal of China Coal Society

基　　金：中国煤炭地质总局双碳科技专项资助项目(ZMKJ-2021-ZX02,ZMKJ-2021-ZX03);中国煤炭地质总局科技创新基金资助项目(ZMKJ-2019-J12)。

摘　　要：锂和稀土元素是我国重要的工业原料和战略性矿产资源,沉积型锂矿床成为国内外研究的热点,具有成为新型锂矿床的潜力。以广西上林县上二叠统合山组底部炭质泥岩为主要研究对象,通过反光显微镜、带能谱扫描电镜、X射线衍射、X射线荧光光谱、电感耦合等离子质谱等测试方法,分析了炭质泥岩的矿物学及元素地球化学特征,研究了炭质泥岩中锂和稀土的赋存状态和物质来源,讨论了炭质泥岩中锂和稀土元素富集的影响因素。结果表明,上林上二叠统合山组底部炭质泥岩中重稀土(重稀土氧化物质量分数为0.024%)接近了我国离子吸附型重稀土的边界品位,部分样品中锂(Li的质量分数大于1000μg/g)达到了国外黏土型锂矿边界品位,找矿潜力巨大;高锂的炭质泥岩中高岭石是锂的主要载体矿物,低锂的炭质泥岩中锂可能主要赋存在伊蒙混层中,稀土元素可能以离子吸附形式存在于黏土矿物(尤其是高岭石)中;炭质泥岩的沉积物主要来源于哀牢山—松马缝合带的二叠纪酸性岩浆岩,部分来自于峨眉山大火成岩省酸性岩浆岩,其中酸性岩浆岩中的云母是锂的主要来源,副矿物(独居石、磷灰石等)是稀土的主要来源;物源区强烈化学风化,是炭质泥岩中锂和稀土富集的主要因素,还原的浅水碳酸盐台地沉积环境是合山组底部炭质泥岩中锂和稀土元素的富集成矿的重要因素。Lithium(Li)and rare earth elements(REE)are essential industrial raw materials and strategic mineral resources in China.Sedimentary lithium deposits have become the focus of research and have the potential to become new lithium deposits.The carbonaceous mudstone from the bottom of the upper Permian Heshan Formation in Shanglin was studied.The mineralogical and geochemical characteristics of the carbonaceous mudstones were analyzed using the reflected light microscopy,SEM-EDS,XRD,XRF,and ICP-MS.The occurrence state and materials sources of Li and REE in the carbonaceous mudstone were examined.Factors affecting the enrichment of Li and REE in the carbonaceous mudstone were discussed.The results show that the heavy rare earth element(HREO content is 0.024%)in the carbonaceous mudstone at the bottom of the upper Permian Heshan Formation in Shanglin is close to the cut-off grade for ion adsorption rare earth elements deposits.Li in some carbonaceous mudstone samples(Li content is>1000μg/g)reaches the cut-off grade for clay-type Li deposits abroad,which has a great prospecting potential.In the high-Li carbonaceous mudstone,Li is mainly hosted by kaolinite,while in the low-Li carbonaceous mudstone,Li is mainly hosted by andreattite,and REE exists in clay minerals(especially kaolinite)in the form of ion adsorption.The carbonaceous mudstone dominantly derived from the Permian acid magmatic rocks associated with Ailaoshan-Song Ma Suture Zone,and some carbonaceous mudstone derived from ELIP acid rocks.Li sourced from mica,and REE was originated largely from accessory mineral(monazite,apatite,etc.)in acid rocks.The strong chemical weathering in provenance is the main factor for the enrichment of Li and REE in the carbonaceous mudstone,and the reduced shallow water carbonate platform sedimentary environment is an important factor for the enrichment of Li and REE in the carbonaceous mudstone at the bottom of Heshan Formation.

关 键 词：合山组 锂 稀土 赋存状态 富集机制 

分 类 号：P618.11[天文地球—矿床学]