Characteristics and distribution of late Carboniferous to early Permian wildfires and their controlling factors

The late Carboniferous to early Permian period is renowned for extensive coal formation and frequent paleowildfires. Nonetheless, the nature and distribution of these wildfires varied significantly over time. In an effort to elucidate the patterns of paleowildfires during the late Paleozoic Ice Age and to probe into the controlling mechanisms of paleowildfires under icehouse conditions, a comprehensive analysis was performed on coal samples from the Taiyuan and Shanxi formations within the Dacheng coalfield of Hebei Province, North China. The dataset was augmented with global inertinite data from the late Carboniferous to early Permian periods and was compared to paleowildfire patterns from the Pliocene to Holocene epochs. The results show that paleowildfires in the Dacheng coalfield of North China transitioned from moderate-scale, low-intensity surface fires to large-scale, relatively high-intensity ground fires. Globally, the distribution of paleowildfires shifted from Euramerica to Gondwana, Cathaysia, and Angara from 300 Ma to 290 Ma, accompanied by a corresponding increase in inertinite content. This spatial and temporal variation in wildfire activity appears to have been strongly influenced by paleoclimate and atmospheric conditions. At 300 Ma, cooler and wetter paleoclimate, coupled with relatively low atmospheric pO₂ levels, likely contributed to a reduced incidence of paleowildfires. In contrast, at 290 Ma, warmer paleoclimate, higher atmospheric pO₂ levels, and the flourishing mires in Gondwana, Cathaysia, and Angara were conducive to more intense paleowildfires. This pattern is further supported by the comparison to more recent icehouse periods. Similar to the late Carboniferous–early Permian period, wildfire activity increased from the Pliocene to the Holocene, highlighting the critical role of climatic conditions in driving wildfire proliferation under icehouse conditions. However, the Pleistocene to Holocene wildfires were less intense than those of the late Carboniferous–early Permian, suggesting that atmospheric oxygen concentrations played a key role in modulating the evolution of the fire systems over geological timescales. These findings underscore the complex interplay between climate, atmospheric composition, and vegetation in shaping wildfire dynamics across Earth’s history.