Paleopeat-forming environments have an important effect on the dispersion and enrichment of trace elements in coal. The C3 coal seam of the Xuanwei Formation in eastern Yunnan was used as a case study to reconstruct the paleopeat-forming environment based on the coal facies parameters and geochemical characteristics, and its influence on trace element (including rare earth elements and yttrium, REY) enrichment was investigated. The C3 coal was classified as medium rank coking coal with an ultra-low moisture content, medium-high-ash yield, and low-medium volatile content. Compared to the average values for Chinese coals, Cu and V were enriched and Co was slightly enriched in the C3 coal. Compared with the average values for world coals, Cu and V were enriched, while several other trace elements were slightly enriched, including Co, Hf, Nb, Sc, Ta, Zn, and Zr in the C3 coal. The C3 coal was deposited in a low peat mainly limno-telmatic swamp, with deep water, weak hydrodynamic conditions, brackish to salty water, and reducing conditions. Trace elements, including Cu, V, Hf, Nb, Sc, Ta, Zr, and REY, are typically enriched in a limno-telmatic environment with fresh water, and reducing and weak hydrodynamic conditions. Additionally, REY and V are also significantly enriched in brackish water limno-telmatic conditions with the same depositional environment.

In China, the majority of mountainous regions are characterized by complex topography and a delicate, sensitive geological environment. Coupled with a generally underdeveloped infrastruc-ture and numerous unreasonable human engineering activities, these regions are often highly susceptible to geological disasters. Geological hazards can cause significant damage to human lives and property, impeding the development of mountainous areas. Consequently, researching the assessment of geological hazard vulnerability is crucial for disaster prevention, emergency management, and economic development in these regions. This study focuses on Xuanwei City and selects eight factors for evaluation, including elevation, gradient, slope aspect, normalized vegetation index, stratigraphic lithology, distance from faults, distance from rivers, and distance from roads. These factors are chosen based on a comprehensive analysis of the spatial and tem-poral distribution of geological hazards and disaster incubation conditions. Two paired models, the deterministic coefficient model + logistic regression model (CF+LR) and the information quan-tity model + logistic regression model (I+LR), were employed to quantitatively assess the study ar-ea. The accuracy of these models was evaluated using ROC curves and AUC values. The results indicate that: (1) The AUC values for the CF+LR and I+LR coupled models are 0.799 and 0.772, respectively, demonstrating that both models can objectively and reliably assess the vulnerability to geological hazards in the study area; (2) Based on the CF+LR model calculations, the geological hazard susceptibility of Xuanwei City can be categorized into four zones: extremely high suscepti-bility (6.09%), high susceptibility (31.08%), medium susceptibility (32.26%), and low susceptibility (30.57%); (3) The CF+LR model more accurately represents the evaluation results and offers a strong reference value.