Geochemical Characteristics of Late Permian Coal in Western Guizhou, China, and Their Paleoenvironmental Significance.

The Late Permian coal deposited in eastern Yunnan and western Guizhou provided a record of changes in the paleoclimate and paleoenvironment before the main episode of the end-Permian mass extinction. Studying the geochemical characteristics of elements of coal provides important insights into the evolution of the paleoenvironment. Focusing on the Late Permian coal of the Longtan Formation from Dawan Mine, Liupanshui Coalfield in western Guizhou, the geochemical characteristics were determined by using X-ray fluorescence spectrometry and inductively coupled plasma-mass spectrometry. The contents of the major elements were depleted to normal compared with that of Chinese coal. Compared to world coal, there was a slight enrichment in Cu, Co, Zr, Hf, V, and Nb, while Ba, Sr, and Cs were depleted, and the other trace elements and rare earth elements were present at normal levels. The salinity- and redox-sensitive proxies (e.g., Sr/Ba, V/(V + Ni), Ce, Sr/Cu, and Ga/Rb, C value), together with the ICV and CIA in the Late Permian coal, suggest that a brackish to salt water and reducing conditions prevailed during the deposition of the Longtan Formation in the Liupanshui Coalfield, western Guizhou. The climate likely transitioned toward hot and humid conditions with stable and intense chemical weathering. During the early coal-forming period, the coal swamp was affected by acid volcanic eruptions and the input of andesite clastic material. The variation in chemical weathering was more pronounced at the end of the Late Permian, suggesting a turbulent terrestrial environment before the peak of extinction.