以山西省大同煤田小峪煤矿的石炭—二叠系太原组优质煤系高岭岩为研究对象，开展了岩相学、矿物学、全岩地球化学、锆石U–Pb年代学和Lu-Hf同位素研究，旨在揭示优质煤系高岭岩的物源和成因机制。研究发现优质煤系高岭岩的矿物成分以高有序度高岭石为主，不含碎屑矿物石英、长石和白云母。部分样品含有勃姆石，是高岭石脱硅蚀变的产物。高岭岩中的锆石是典型的岩浆锆石，且年龄均一，集中在300 Ma左右，与煤层的沉积年龄一致，证实它们由火山灰蚀变形成。此外，高岭岩中普遍含有板/柱状和蠕虫状高岭石，也是火山灰蚀变的典型特征。这些粗晶高岭石认为是由火山灰中的晶屑，例如斜长石和黑云母等，蚀变形成的假象高岭石。锆石的ε_Hf(t)以变化范围较大的负值为主，指示产出锆石的岩浆主要来源于古老大陆地壳物质的重熔，与华北北缘内蒙古隆起上同期大陆弧火山作用形成的岩浆岩锆石ε_Hf(t)一致，说明它们之间存在同源关系。锆石的微量元素地球化学指纹也指示锆石的产出岩浆来源于大陆弧构造背景。华北克拉通北缘在晚古生代时期是安第斯型大陆边缘，在晚石炭—早二叠纪的聚煤时期，其北部的古亚洲洋板片在华北克拉通之下持续南向俯冲，诱发了频繁的大陆弧火山作用。喷发的火山灰降落在华北海陆过渡的泥炭沼泽中，经淋滤蚀变形成煤系高岭岩。

The petrographical, mineralogical, whole-rock geochemical, and zircon U-Pb geochronological and Lu-Hf isotopic studies were carried out for investigating the provenance and genetic mechanism of the high-grade coal-bearing kaolin within the coal seams of the Permo-Carboniferous Taiyuan Formation in the Xiaoyu mine of the Datong coalfield, Shanxi Province. The coal-bearing kaolin is composed mainly of well-ordered kaolinite with no detrital quartz, feldspars and muscovite. Some samples contain boehmite that were formed through the desilication of kaolinite. The zircons in the coal-bearing kaolin are typically igneous origin with only one age population of ca. 300 Ma, same with the depositional age of the coal, confirming that the coal-bearing kaolin was altered from volcanic ash. Besides, the coal-bearing kaolin commonly contains tabular/columnar and vermicular kaolinite that are also diagnostic feature of alteration from volcanic ash. These coarse-grained kaolinites are thought to be pseudomorphic kaolinite altered from crystal fragments in volcanic ash, such as plagioclase and biotite. The zircon ε_Hf(t) is dominant by a wide range of negative values, indicative of their formation from magma generated by substantial remelting of ancient continental crust, coinciding with that of contemporaneous magmatic rocks formed from continental arc volcanism in the Inner Mongolia Paleo-Uplift at the northern margin of North China. This suggests their cognate relationship. The geochemical fingerprints of trace element of zircons also indicate that they were crystalized from continental arc magma. The northern margin of the North China Craton (NCC) is an Andean-type continental margin in the late Paleozoic. During the coal-accumulating period of the Late Carboniferous to Early Permian in North China, the Paleo-Asian Ocean (PAO) plate was continuously southward subducted beneath the NCC, resulted in a frequent continental arc volcanism. The emitted volcanic ash fell into peat swamps developed in a paralic environment in North China, which were subjected to an intensive leaching and altered to the coal-bearing kaolin.