First report of Cisuralian (early Permian) charcoal layers within a coal bed from Baode, North China with reference to global wildfire distribution

Fossil charcoal is reported for the first time from a Cisuralian coal bed of the Shanxi Formation in the Qiaotou Section, Baode, Shanxi, North China. Based on anatomical characteristics, these charcoal fragments consist of coniferous or cordaitalean xylem, unidentified primary xylem and cordaitalean and possible fern leaves. These charcoal fragments represent the evidence of palaeowildfire taking place in tropical peat swamps during the Cisuralian in Cathaysia. The palaeowildfire is most likely to be a surface fire and burning litter and shrubby vegetation. Fire frequency for this early Permian peat swamp might have been on the order of 176–(294–588)–1429years, close to modern values. Compared with modern analogues, the North China Block during the Cisuralian was probably wet in general but could be occasionally seasonally dry for short time intervals. Previous charcoal and inertinite records moreover indicate that palaeowildfires were globally common during the Cisuralian. Overall, more wildfire evidence was found in the Artinskian–Kungurian than the Asselian-Sakmarian (except in the Euramerican Realm), probably due to more suitable regional climate, vegetation to fuel fires and taphonomic circumstances.