Synergistic astronomical-volcanic controls on coal accumulation in the Late Permian coal measures of western Guizhou

Abstract

Multiple coal seams within the Upper Permian succession of western Guizhou exhibit pronounced vertical cyclicity and are interbedded with volcanic ash-bearing layers, suggesting developmental patterns potentially linked to coupled astronomical-volcanic forcing. This study investigates the controls of astronomical orbital forcing and synsedimentary volcanism (constrained by zircon geochronology) on coal seam development in the Late Permian coal-bearing strata of western Guizhou. Results indicate that most coal seams accumulated during periods of high eccentricity. During high eccentricity intervals, the amplification of precession-driven seasonal insolation contrasts intensified monsoon precipitation, promoting humid conditions. Meanwhile, adequate accommodation allowed the accumulation and preservation of terrestrial vegetation. Geochemical and sedimentological analyses reveal that volcanic ash-bearing layers primarily occur as floors or partings of coal seams. Volcanic activity likely enhanced regional nutrient availability, which in turn may have promoted plant growth and peat accumulation. Gases, aerosols, and pyroclastic materials released by volcanic eruptions could have further stimulated plant growth through climate modification and nutrient supply. Therefore, the development of most coal seams in this region was likely co-controlled by astronomical forcing and volcanic activity. In contrast, shifts in astronomical orbital phases (eccentricity) could alter sedimentary environments by modulating climate and sea-level, thereby terminating sustained peat accumulation. Collectively, these findings demonstrate the response of coal accumulation to astronomical forcing and volcanic activity over geological timescales.