Wildfires in Late Paleozoic Strata in Brazil

During the late Paleozoic, Gondwanan ecosystems experienced a gradual transition from icehouse to greenhouse conditions. With the retraction of Late Paleozoic Ice Age (LPIA) ice sheets, a diversity of paleoenvironments formed, and these are preserved in geological strata exposed in the Brazilian Paraná and Parnaíba basins. While at medium-high latitudes of the Paraná Basin humid settings experienced a gradual increase in aridity, at the low latitudes of the Parnaíba Basin, the previous semi-arid environments were transformed in desertic areas. This environmental pressure acted directly on the vegetation and, as wildfires are dependent on the availability of biomass (=vegetation), the occurrence of such fire events was also affected throughout the interval, and the presence of charcoal as direct evidence of paleo-wildfires varies. In the Paraná Basin, charcoal is rare in the Pennsylvanian deposits of the Itararé Group, getting abundant in the coal-bearing strata of the Cisuralian Rio Bonito Formation and becomes rare again in the uppermost Passa Dois Group (Guadalupian). In the Parnaíba Basin, charcoal is rare, and the only record described so far comes from the Permian Motuca Formation. Although the description of charcoal occurrences in Brazilian basins increased since the first records, a lack of data is still evident. More detailed anatomical and taxonomical studies are necessary to support both paleofloristic and paleoenvironmental interpretations.