Early Permian bioevent in the fusulinacean fauna of South China

摘要

Analysis of a large database of the stratigraphic distribution of fusulinacean Foraminifera reveals an Early Permian event of significant decline of species diversity in South China. Data from Late Carboniferous to Early Permian sections without apparent unconformity in southwest China were evaluated to determine if the apparent pattern of species disappearance was caused by bias in fossil preservation associated with Early Permian sea-level changes. Statistical analysis suggests that the Early Permian event started in the Late Sakmarian with a significant drop of species diversity in the Robustoschwagerina ziyunensis Zone and continued through the Pamirina darvasica Zone of the Artinskian and into the Brevaxina dyhrenfurthi Zone of the Early Kungarian, resulted in a total loss of about 40% species diversity in the fusulinacean fauna. The Early Permian event is the most extensive bioevent in the history of fusulinacean Foraminifera at the species level although it is less significant at the generic level. Because a similar faunal change has been found among the fusulinacean assemblages in North America and in various regions of Tethys, this event may represent a major faunal turn-over in response to the Early Permian changes in sea level and could be of a global nature. Previous recognition of this event was hampered by Early Permian unconformities in North America and other regions of Tethys.