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 coal-bearing 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.

Based on the analysis of tectonic background and coal-accumulating environment of Jungar coalfield, the coal petrological characteristics, inorganic mineral composition, distribution and occurrence regularity of coal and gangue in No.6 coal of the Junger coalfield are studied, and the genesis is determined byutilizing the research methods of coal petrology, mineralogy and geochemistry.The study shows that the average contents of the inertinite, vitrinite and exinite in the maceral of No.6 coal in the study area are 59 %, 28 % and 13 %, respectively.Compared with the Late Paleozoic coals in other areas of North China, the content of the inertinite is high, which reflects an adequate supply of surface water during the formation of No.6 coal seam.The main inorganic minerals in coal and gangue are kaolinite and boehmite, associated with quartz, calcite, siderite, pyrite, anhydrite, anatase and svanbergite.The vertical changes of the mineral composition and main chemical elements of No.6 coal indicate that the middle of the coal seam is rich in boehmite, while the upper and lower parts are rich in kaolinite.There are three origins of kaolinite: colloidal precipitation crystallization, terrestrial transport sedimentation and volcanic ash alteration.And there are two origins of boehmite: alumina colloidal precipitation crystallization and desilication alteration of kaolinite.