Floral Diversity Data in the Assessment of Paleoclimate in the Parana Basin,Southern Brazil

摘要

The comparative analysis of floral diversity data on Permian rocks from the Parana Basin,Brazil,and nine Australian basins revealed that the South American and the Australian basins bear completely different floral-diversity signatures.The Parana Basin displays a peak in microfloral diversity during deposition of the coal-bearing Rio Bonito Formation,followed by a steady decrease during the Middle and Late Permian,whereas diversity in Australia remained high throughout the Permian.These data suggest that,while the flora in the Parana Basin was submitted to more stressful conditions as the continent moved from humid,temperate zones into subtropical,desertic ones,the flora in Australia thrived under persistently humid conditions.Therefore,the increased aridity recorded by the Permian rocks in the Parana Basin is more likely to be due to the northward migration of western Gondwana across climate zones rather than a global trend throughout the Permian.