## 2 Regional Geological Setting  
The study area is situated at the junction of the Yangtze Block, the Yuechengling Fold Belt within the Northern Guangxi Block, the Nanhua Mobile Belt, and the Haiyangshan Uplift in the Central-Northeastern Guangxi Fold System. The regional topography descends from the west to the east, with the western area comprising a mid-low mountainous region at elevations exceeding 1000 m, which is characterized by steep terrain, intense dissection, and the frequent occurrence of sharp peaks and conical summits along ridgelines. To the east lies a hilly area with altitudes ranging from 300 to 500 m, and this area is characterized by gentle slopes, rounded mounds, partially exposed bedrock, and a relative height difference of less than 200 m. The uranium deposit is situated within the transitional zone between the mid-low mountains and hilly domains (Figure 1) [21].  
The stratigraphic sequence within the study area exhibits relatively complete exposure, with strata from the Proterozoic to Quaternary systems displaying varying degrees of outcrop, except for the absence of the Silurian and Triassic systems. The lithology is predominantly composed of sandstone, with the Devonian, Carboniferous, and Ordovician systems being the most extensively distributed. Notably, the Middle-Upper Devonian series constitutes the principal ore-bearing strata within the mining field. The tectonic evolution demonstrates multiphase superposition characteristics. The Caledonian Orogeny resulted in the folding and uplift of the Lower Paleozoic strata, resulting in the formation of the Yuechengling Anticline, the Daxijiang Syncline, and the Fenghuangtian Anticline. This process was accompanied by large-scale magmatic intrusions and the development of synkinematic faults, such as the Baishi Major Fault. Subsequently, the Indochinese Orogeny reactivated the uplift and basement faults of the Upper Paleozoic strata, forming several fault zones within the Devonian system on the western wing of the Daxijiang Syncline. These include the F1 and F3 interlayer compression fracture zones, the NE-trending F2 fault zone group (F\({}_{2}^{0}\), F\({}_{2}^{1}\), F\({}_{2}^{2}\), and F\({}_{2}^{3}\)), the F11 cross-cutting fault zones, and the east-west fault zone group. All these structures are closely associated with mineralization processes. The Yanshanian block faulting ultimately shaped the Daxijiang syncline, which comprises platform cover strata displaying arc-shaped bending with an eastward convex apex, which is characterized by a narrow and uplifted northern termination and broad subsided southern portion superimposed upon the Caledonian fold basement rift trough. Under E-W-trending extensional stress during the Himalayan period, the Daxijiang-Longshui fault-depression basin was formed (Figure 2) [22]. The location and morphology of uranium orebodies are  
Figure 1: Location diagram of the study area in various administrative divisions of China, Guangxi and the northern of Guangxi (**a–d**).  
controlled by fault-bounding grabens and interlayer fracture zones; the orebodies mainly occur as stratiform, lenticular, vein-type, and irregular shapes [23]. Magmatic rocks are widely distributed in the area, predominantly consisting of Caledonian medium-grained to coarse-grained and medium-grained to fine-grained porphyritic biotite granites, exhibiting an average uranium content of 16.5 \(\times\) 10\({}^{-6}\) and zircon U-Pb isotopic ages of 414 Ma. These are accompanied by Yanshanian fine-grained biotite granites with higher uranium enrichment (26.2 \(\times\) 10\({}^{-6}\)) and isotopic ages ranging from 152 to 201 Ma (zircon U-Pb dating), and they are classified as uranium-enriched granitic bodies. The multiphase and multistage magmatic intrusions ultimately constituted the Yuechengling composite granite batholith, which is presumed to have contributed partial metallogenic materials for uranium mineralization [24].