A mixed mid-Permian marine fauna from the Yanji area, northeastern China: A paleobiogeographical reinterpretation

Abstract Paleobiogeographically mixed marine faunas have been well recognized from many Permian marine sequences in northeast China. These mixed faunas are normally associated with Monodiexodina fusulinid assemblages. The mixed faunas are characterized by an admixture of both paleo-tropical Cathaysian taxa and cool-temperate elements. In addition, endemic taxa, especially at a specific level, and anti-tropical forms, are also very distinctive.
Previously, the presence of anti-tropical taxa in these mixed faunas has been used to argue that some of the northeast Asian terranes may have originated from northern Gondwana during the Permian, where they may have been m close proximity to Tibet. However, this interpretation is contrasted by the view offered in this paper. It is argued that the anti-tropical distribution of marine taxa is a normal, predictable biogeographical phenomenon that is probably controlled by certain climatic conditions. Permian anti-tropicality seems to have occurred most strongly during the Late Artinskian to Ufimian, probably in association with the presence of distinct mesothermal climatic zones at the time. In the present study we report a mixed mid-Permian marine fauna (fusulinids and brachiopods) from the Dasuangou Formation of the Yanji area in the eastern Jilin Province of northeast China, and discuss its possible origin in the context of Permian paleogeography and the climates of eastern Pangea.