The flora of Early Permian coal measures from the Paraná Basin in Brazil: A review

Abstract

This paper presents an updated overview integrating both previous and newly published data on the most important floras found associated with Early Permian coal seams in the Paraná Basin, Brazil. These floras occur within the Rio Bonito Formation and correspond to the Gondwana “Glossopteris Flora.” For this review, five floras are selected, in ascending stratigraphic order: the “São João do Triunfo,” “Figueira,” “Quitéria,” “Morro do Papaléo” and “Irapuá Bed” floras. They are the best-known floras of the basin in terms of taxonomic composition, paleoecology and environments of deposition. An early–mid Sakmarian to earliest Artinskian age is indicated for the Rio Bonito Formation based on absolute radiometric and relative biostratigraphic ages. Integration of available information about the selected floras allows evaluation of taphonomic and paleoecological factors to provide a more comprehensive understanding of the Early Permian floral record in the Paraná Basin. The variation observed in both the taxonomic composition of individual floras and in the frequency of occurrence of different plant groups is due to the broad range of environmental/edaphic conditions that prevailed in the many different depositional settings represented in the Rio Bonito Formation. A more precise age determination obtained for the plant-bearing deposits permits the establishment of a more confident correlation between the Early Permian floral succession in the Paraná Basin and other Early Permian floral successions in other basins. The Sakmarian global warming favored the appearance of pecopterid and sphenopterid ferns amongst the spore-producing plants, and the glossopterids amongst the pollen-producing plants.