Geochemistry of the Late Permian Coal in Northeast Yunnan, China: Provenance and Paleoenvironmental Implications

The Late Permian was characterized by significant and concurrent transformations in Earth's biological, climatic, and environmental systems. The Weixin region in the eastern Yunnan Province contains extensive Late Permian coal deposits, providing an ideal setting for investigating paleoenvironmental and paleoclimatic changes. Using X-ray fluorescence spectrometry and inductively coupled plasma mass spectrometry, we analyzed major element, trace element, and rare earth element concentrations in 40 whole-layer samples from five coal seams within the Late Permian Xuanwei Formation at the Yujing Mountain Mining Area. The results indicate that the elements in the Late Permian Xuanwei Formation coal of Yujing Mountain, Weixin, Yunnan, are relatively enriched in the coal layers near the roof and floor strata as well as in the lower C7 coal seam. This enrichment may be associated with high ash content and leaching processes, providing valuable insights for prospecting critical metal enrichment in the study area. During the coal-forming period, the study area experienced frequent alternations between dry and wet climatic conditions and recurrent marine transgressions, with an overall transition from a hot and humid environment to a warm and humid climate. The provenance of the study area shows mixed sources, with the source rocks primarily derived from the Emeishan large igneous province to the north.