伊犁盆地南缘蒙其古尔铀矿床东部黏土矿物分布特征  

Distribution characteristics of clay minerals in eastern part of the Mengqigur uraniumdeposit in southern margin of the Yili Basin

作　　者：陈程 王福东[1] 张虎军[1] 方敏[1] CHEN Cheng;WANG Fudong;ZHANG Hujun;FANG Min(Geologic Party No.216,China National Nuclear Corporation,Urumqi 830011,Xinjiang,China)

机构地区：[1]核工业二一六大队,新疆乌鲁木齐830011

出　　处：《矿产勘查》2023年第1期60-68,共9页Mineral Exploration

基　　金：中国核工业地质局“新疆伊犁盆地砂岩型铀矿资源调查评价与勘查”项目(202205)资助。

摘　　要：伊犁盆地南缘蒙其古尔铀矿床是近年来探寻出的储量可观的铀矿床之一,含矿岩系主要为下侏罗统三工河组上、下段及中侏罗统西山窑组上、下段。本文通过X射线衍射、扫描电镜等分析测试手段,初步探讨含矿岩层砂体黏土矿物分布特征及转化关系。研究发现蒙其古尔铀矿床东部地区黏土矿物以高岭石为主,其次为伊利石、伊利石/蒙脱石混层,少量绿泥石及蒙脱石。黏土矿物种类及含量随地层埋深增加及地下水运移方向存在一定的变化规律:随深度增加高岭石含量呈递增趋势,伊利石/蒙脱石混层呈递减趋势,伊利石呈微弱递增趋势;沿地下水运移方向高岭土含量持续递减,伊利石/蒙脱石混层含量呈递增趋势,伊利石呈微弱递减趋势。高岭石一部分为陆源碎屑成因,另一部分为成岩初期的次生产物;伊利石大部分是成岩前期的自生矿物,另一部分则是由蒙脱石最终转换而成;伊利石/蒙脱石混层则是蒙脱石向伊利石过渡转化的中间产物。高岭石和伊利石/蒙脱石混层含量呈明显负相关性;伊利石和伊利石/蒙脱石混层表现为微弱负相关,高岭石和伊利石二者相关性较差,表明由原生矿物长石、云母等转变成伊利石与高岭石,并且存在高岭石向蒙脱石及绿泥石的转化,而蒙脱石经伊利石/蒙脱石混层中间产物后向伊利石转化的过程。The Mengqigur uranium deposit in the southern margin of Yili Basin is one of the uranium deposits with considerable reserves discovered in recent years.The ore-bearing rock series are mainly the upper and lower members of Sangonghe Formation of Lower Jurassic and the upper and lower members of Xishanyao Formation of Middle Jurassic.In this paper,the distribution characteristics and transformation relationship of clay minerals in ore-bearing sand bodies are preliminarily discussed by means of X-ray diffraction and scanning electron microscopy.It is found that kaolinite is the main clay minerals in the eastern part of Mengqigur uranium deposit,followed by illite,illite/montmorillonite mixed layer,a small amount of chlorite and montmorillonite.The species and content of clay minerals change with the increase of depth and the direction of groundwater migration.With the increase of depth,the content of kaolinite increases,the illite/montmorillonite mixed layer decreases,and illite increases slightly.Along the direction of groundwater migration,kaolin content decreased continuously,illite/montmorillonite mixed layer content increased,and illite content decreased slightly.Part of kaolinite is terrigenous clastic origin,and the other part is secondary product of early diagenesis.Most illite is the autogenetic mineral of prediagenesis,while the other part is the final conversion from montmorillonite.Illite/montmorillonite mixed layer is the intermediate product of montmorillonite to illite transition.The content of kaolinite and illite/montmorillonite mixed layer is negatively correlated.Illite and illite/montmorillonite mixed layers show a weak negative correlation,and kaolinite and illite are poorly correlated,indicating that the primary minerals such as feldspar and mica are transformed into illite and kaolinite,and there is a transformation process of kaolinite to montmorillonite and chlorite,and montmorillonite to illite after the intermediate product of illite/montmorillonite mixed layer.

关 键 词：黏土矿物特征 黏土矿物成因 成矿环境 蒙其古尔铀矿床 伊犁盆地南缘 

分 类 号：P577[天文地球—矿物学]