大同煤田煤系高岭岩赋存特征和成矿机理研究

Occurrence characteristics and formation mechanism of coal-bearing kaolinite rocks in Datong coalfield

大同煤田含煤地层中富含具有工业价值的高岭岩资源,为了确定这些煤系高岭岩的赋存特征和成矿机理,本文以大同煤田晚古生代太原组的高岭岩矿床为研究对象,采用野外地质调查、室内显微镜鉴定、XRD分析和地球化学分析等研究方法,对煤系高岭岩的赋存层位、结构组成、岩石类型及成因进行研究。结果表明:研究区高岭岩主要赋存在9号煤底板、8号煤底板、3-5号煤底板、3-5号煤夹矸和2号煤底-3号煤顶层间5个层位;岩石主要矿物成分为高岭石(含量60%~90%),其次为石英,以及少量的长石、云母、菱铁矿、硬水铝石、锐钛矿等;高岭岩结构组分可划分为颗粒、高岭石晶粒、矿物碎屑和基质,岩石类型包括晶粒状高岭岩、隐晶质高岭岩、团块状高岭岩和砂质高岭岩;煤系高岭岩的成因主要为陆源搬运沉积形成和火山灰蚀变形成两种。

The kaolinite rocks,a resource of industrial value,are abundant in the coal-bearing strata of the Datong coalfield.To look into the occurrence characteristics and formation mechanism of coalbearing kaolinites,this paper uses the kaolinite deposits in the Taiyuan formation of the Late Paleozoic in the study area as the research object.The occurrence horizon,structural composition,rock type and genesis analysis of the kaolinite deposit were studied through field geological survey,microscopic identification,XRD analysis and geochemical analysis.Results show that the kaolinite rock in Datong coalfield is mainly located in five layers,including the No.9 coal floor,the No.8 coal floor,the No.3 and 5 coal floor,No.3 and 5 coal parting and the No.2 coal floor to No.3 coal roof.The kaolinite is the predominant mineral(the content is between 60%and 90%)associated with minor minerals like quartz,feldspar,mica,anatase,siderite and diaspore.The micro-components of the kaolinite rock in the study area were divided into grains,kaolinite crystals,mineral clasts and matrix.In addition,the kaolinite rock in the study area were categorized as grain kaolinite rock,cryptocrystalline kaolinite rock,lump kaolinite rock and sandy kaolinite rock according to the present morphology analysis.In conclusion,the genesis of kaolinite rock is mainly terrigenous transport sedimentary and volcanic ash.