The origins of partings within the Late Carboniferous No. 6 coal in the Jungar Coalfield, North China, and their relationship to the enrichment of critical metals in the coal, is poorly understood. This study combines UPb ages and LuHf isotope data of zircon, whole-rock geochemistry, LA–ICP–MS elemental mapping, and selective chemical extraction experiments to investigate the provenance of the partings and the occurrence mode of critical metals in the partings collected from the exploration area in the northwest of the Jungar Coalfield. It was found that the zircons in the kaolinite-dominant partings yielded a single age group of ca. 300 Ma at the latest Carboniferous (Gzhelian), indicating that the partings are alteration products of air-fall volcanic ash (tonsteins). The zircons are characterized by negative εHf(t) values and a continental arc tectonic setting, suggesting a genetic connection between the volcanic ash and the Late Paleozoic continental arc that existed in the Inner Mongolia Paleo-Uplift, related to the southward subduction of the Paleo-Asian oceanic plate beneath the northern margin of the North China Block. During the devitrification of volcanic glasses to kaolinite in the mires, the incompatible elements, such as Nb, Ta, Zr, Hf, and rare earth elements (REEs and Y, REY), preserved in the volcanic glasses were leached out as they are incompatible with the crystal lattice of kaolinite. Niobium and Ta, similar to Ti in ionic radii, were preferentially incorporated into fine-grained Ti oxides as reprecipitated products in the alteration process of volcanic ash. The enrichment of Nb, Ta, and Ti in organic matter in the tonsteins suggests that they have some mobility during alteration of volcanic ash and could be, to some extent, transported into the enclosing peats. Zirconium, Hf, and REY were fixed by organic matter admixed with the volcanic ash after their deposition in the mires. Meanwhile, they could also be transported into the enclosing peats, as no secondary minerals formed could substantially retain them. Although Li and Ga were able to be incorporated into the crystal lattice of kaolinite during their crystallization, they could also be transported into the enclosing peats due to their fluid-mobile nature. Both the leaching of a voluminous amount of volcanic ash contacting with the peats and the input of the volcanic ash as an admixture into the peats contributed to the enrichment of critical metals in the Late Carboniferous coal in the Jungar Coalfield.

华北准噶尔煤田晚石炭世 6 号煤的裂解起源及其与煤中关键金属富集的关系知之甚少。这项研究结合了 U Pb 年龄和 Lu西北勘探区采集的锆石Hf同位素数据、全岩地球化学、LA-ICP-MS元素图谱和选择性化学萃取实验研究分理的物源和分理中关键金属的赋存模式准噶尔煤田。结果发现，以高岭石为主的分区中的锆石产生了约 100 年的单一年龄组。最晚石炭纪（Gzhelian）300 Ma，说明裂隙为空降火山灰（tonsteins）蚀变产物。锆石具有负εHf(t)值和大陆弧构造背景的特征，表明火山灰与内蒙古古隆起存在的晚古生代大陆弧之间存在成因联系，与华北地块北缘古亚洲洋板块向南俯冲有关。火山玻璃在泥浆中反玻化为高岭石过程中，保留在火山玻璃中的不相容元素Nb、Ta、Zr、Hf和稀土元素（REEs和Y、REY）因不相容而被浸出与高岭石的晶格。离子半径与 Ti 相似的铌和 Ta 在火山灰蚀变过程中作为再沉淀产物优先结合到细粒 Ti 氧化物中。tonsteins 中有机质中 Nb、Ta 和 Ti 的富集表明它们在火山灰蚀变过程中具有一定的流动性，并且在某种程度上可能被输送到封闭的泥炭中。锆、Hf、和 REY 在沉积在泥潭中后被有机物与火山灰混合固定。同时，它们也可以被输送到封闭的泥炭中，因为没有形成的次生矿物可以大量保留它们。尽管 Li 和 Ga 在结晶过程中能够结合到高岭石的晶格中，但由于它们的流动性，它们也可以被输送到封闭的泥炭中。大量火山灰与泥炭接触的淋滤作用以及火山灰作为混合物进入泥炭中，均有助于准噶尔煤田晚石炭世煤中关键金属的富集。因为没有形成的次生矿物可以大量保留它们。尽管 Li 和 Ga 在结晶过程中能够结合到高岭石的晶格中，但由于它们的流动性，它们也可以被输送到封闭的泥炭中。大量火山灰与泥炭接触的淋滤作用以及火山灰作为混合物进入泥炭中，均有助于准噶尔煤田晚石炭世煤中关键金属的富集。因为没有形成的次生矿物可以大量保留它们。尽管 Li 和 Ga 在结晶过程中能够结合到高岭石的晶格中，但由于它们的流动性，它们也可以被输送到封闭的泥炭中。大量火山灰与泥炭接触的淋滤作用以及火山灰作为混合物进入泥炭中，均有助于准噶尔煤田晚石炭世煤中关键金属的富集。