滇西保山和腾冲地区二叠纪珊瑚及其古地理意义

The Cimmerian Continent is composed of several allochthonous blocks,including the Shan⁃Thai,Tengchong,Baoshan,Lhasa,southern Qiangtang,southern Afghanistan,and southern Iran blocks. It was located between the Gondwanan and Eurasian continents during the Permian Period. The Baoshan and Tengchong blocks,as ones of the important parts of the Cimmerian Continent,splitted from the northern margin of Gondwana in the Early Permian,then drifted northward during the Middle Permian⁃Late Permian. This special latitudinal shift resulted in the occurrence of the cold shallow⁃water Cyathaxonia assemblage,and warm shallow⁃water large solitary and compound rugose corals in the Lower and Middle Permian respectively from these two blocks. The Middle Permian yields Iranophyllum sp.,Pavastehphyllum sp.,Thomasiphyllum cf. spongifolium,Wentzelloides sp.,Naoticophyllum sp.,Wentzellophyllum persicum,in the Baoshan Block,and Lonsdaleiastraea sp. A,Lonsdaleiastraea sp. B,Wentzelellites sp.,Thomasiphyllum tengchongense,Waagenophyllum kueichowense in the Tengchong Block. Only a same genus Thomasiphyllum developed in the Middle Permian of these two blocks,which is also widely developed in the Middle Permian of the Cimmerian Continent. Only few co⁃occurrence of coral taxa between the Baoshan and Tengchong blocks may indicate that the two blocks are not close during the Middle Permian. Compared with the high diversity of rugose corals in the low⁃latitude South China Block during the Middle Permian,much lower diversity of rugose corals occurred in the Baoshan and Tengchong blocks,which implies that these two blocks could have not reached at warm,low latitude during this time.

Keywords： rugose coral ; Permian ; the Cimmerian Continent ; paleobiogeography