## 2 Study Area Characterization  
The research site is situated in the Xiaolong Coal Mine, Bukeser Mongolian Autonomous County, Xinjiang Uygur Autonomous Region. The geological overview map of the study area is shown in Figure 1. The area benefits from a well-developed external transportation network, favorable terrain conditions, nearly horizontal strata, and minimal dip angle variations. The geological formations within the mining area, arranged from oldest to youngest, include the Lower Permian Lower Kalagang Formation (P\({}_{1}\)k), Lower Jurassic Badaowan Formation (J\({}_{1}\)b), Lower Jurassic Sangonghe Formation (J\({}_{1}\)s), Middle Jurassic Xishanyao Formation (J\({}_{2}\)x), Middle Jurassic Toutunhe Formation (J\({}_{2}\)t), Neogene Eocene Oligocene Wulungue Formation (E\({}_{2-3}\)w), and Quaternary (Q). The Lower Permian Kalagang Formation (P\({}_{1}\)k) comprises continental intermediate-acid volcanic rocks. The Lower Jurassic Badaowan Formation (J\({}_{1}\)b) represents a transition from braided fluvial to lacustrine, peat bog, and lacustrine delta coal-bearing sedimentary facies, characterized mainly by gray and dark gray siltstone, fine sandstone, and occasional medium to coarse sandstone and gravel layers. The Lower Jurassic Sangonghe Formation (J\({}_{1}\)s) consists of shallow lake and lakeside facies, predominantly composed of gray and dark gray siltstone and fine sandstone with intermittent medium to coarse sandstone, gravel, carbonaceous mudstone, and coal seams. The Middle Jurassic Xishanyao Formation (J\({}_{2}\)x) is oriented in a NE-SW direction in the southwest part of the mining area, forming part of the Kuluntiebuanticline and containing coal deposits. The Middle Jurassic Toutunhe Formation (J2t) is visible in the western section of the mining area, exhibiting variegated clastic deposits of fluvial and lacustrine facies, primarily conglomerate, sandstone, siltstone, mudstone, and sporadic coal and siderite layers. The formation's upper portion comprises coarse to fine sandstone and argillaceous siltstone, while the lower section is characterized by conglomerate, gravel, coarse sandstone, fine sandstone, and mudstone, with loosely cemented sandstone and conglomerate. The Eocene to Oligocene Wulunguhe Formation (E2-3w) is distributed in a strip pattern to the north of the mining area, representing fluvial and lakeside deposits, predominantly consisting of pale yellow, gray-green, and purplish red striped mudstone, conglomerate, sandstone, gray-white quartz sandstone, and fine-grained quartzite. The Quaternary (Q) deposits are composed of alluvial and diluvial gravel, sand, subsandy soil, and clay. The surface layer is Gobi gravel, loosely cemented, while the lower layer is semi-cemented, with a thickness ranging from 0-30 m.  
The exposed strata surrounding the Xiaolong Mine Field predominantly consist of sandstone, mudstone, and gravel sandstone. In this study, resistivity measurements of 200 rock ore samples with a common lithology (sandstone, mudstone, gravel sandstone, and coal) in the survey area were conducted using the GDD SCIP physical property measuring instrument. The sampling points were evenly distributed across the exposed bedrock area of the entire survey area. The measurement results are presented in Table 1. The analysis of the data reveals that the resistivity of sandstone is approximately double that of mudstone, attributed to its higher porosity. Gravel sandstone exhibits slightly higher resistivity than sandstone due to its increased gravel content. The resistivity of coal in the area is notably higher, with an average resistivity of approximately 187 \(\Omega\)-m. The variations in resistivity among the different rock types in the survey area offer a foundational understanding for the application of the TEM and the anomaly analysis.  
Figure 1: Geological overview of the study area.