山西省煤系铝土矿资源丰富，深部铝土矿资源评价正逐步开展，为进一步确定煤中铝资源禀赋，探求高效勘查方法，以山西孝义地区上石炭统煤系铝土矿层为研究对象，选取并采集了3个钻孔的37个样品，应用显微光学分析、XRD、SEM、XRF和ICP-MS等技术方法，在分析煤系铝土矿层沉积环境和成矿物源的基础上，研究铝土矿中铀(U)、钍(Th)元素的赋存状态与富集成因，探讨U、Th元素的地球化学特征与自然伽马异常的响应关系。结果表明，研究区铝土矿层形成于海相碱性弱氧化为主的沉积环境，沉积过程中存在氧化、弱氧化–弱还原和还原环境，且氧化还原条件不断发生微弱变化；铝土矿与其顶板黏土岩(矿)物源相似，主要源自酸性岩浆岩，而底板铁质岩的物源则与玄武岩或钙质泥岩有关；铝土矿层U、Th元素异常富集主要受控于物源母岩类型及铝土矿、黏土矿物和含钛矿物的吸附能力；铝土矿中富集的U、Th元素是自然伽马高异常的主要原因，且Th元素的贡献较U元素明显。研究结果对划分煤系铝土矿和围岩、确定煤系铝土矿的层位及推测矿体厚度具有实际意义，并对开展深部煤系铝土矿勘探与开发也具有理论指导意义。

Shanxi Province boasts abundant bauxite resources occurring in coal measure strata, with the deep bauxite resources in this province subjected to progressive assessment. This study aims to further determine the endowment of aluminum resources within coals in the province and explore efficient exploration methods. To this end, this study investigated the bauxite layers in Upper Carboniferous coal measure strata in the Xiaoyi area, Shanxi Province. It examined 37 samples from three boreholes using methods such as optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence spectrometry (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). Based on the analysis of the sedimentary environment and metallogenic provenance of the bauxite layers in coal measure strata, this study delved into the occurrence states and enrichment genesis of uranium (U) and thorium (Th) elements in bauxite and explored the correlations of the geochemical characteristics of U and Th with the natural gamma-ray (GR) anomalies. The results show that: (1) The bauxite layers in the Xiaoyi area were formed in a sedimentary environment dominated by marine, alkaline, and slightly oxidizing conditions. Furthermore, oxidizing, slightly oxidizing - slightly reducing, and reducing environments also existed in the sedimentary process, suggesting constantly slight changes in the redox conditions. (2) The bauxite, sharing similar provenance with clay rocks (ores) on its roof, originates primarily from acidic magmatic rocks, while ferruginous rocks on its floor are associated with basalts or calcareous mudstones. (3) The anomalous enrichment of U and Th elements in the bauxite layers is primarily dictated by the parent rock types in the provenance area, as well as the adsorption capacity of bauxite and clay and titanium-bearing minerals. (4) The high GR anomalies of the bauxite are primarily induced by the enriched U and Th elements, with Th elements contributing more significantly than U elements. The results of this study hold practical significance for distinguishing bauxite in coal measure strata from surrounding rocks, determining the bauxite’s horizons, and predicting the thicknesses of ore bodies. The results can also serve as a theoretical guide for the exploration and exploitation of deep bauxite in coal measure strata.