世界二叠纪生物礁的基本特征及其古地理分布

世界上早二叠世生物礁分布于泛大陆的西北陆棚、乌拉尔山脉的西侧、美国的二叠盆地等地，并集中分布于前两个地区。其早期，以Palaeoaplysina礁或Palaeoaplysina和叶状藻礁占优势，而至晚期则形成以Shamovella (Tubiphytes)和苔藓虫为骨架的礁。中二叠世栖霞期的礁仅发现于北美格拉斯山脉、帕米尔和我国的阿尔格山等地。茅口期的礁是世界上最发育的生物礁之一，北美瓜德罗普山脉的二叠纪礁已成为世界上最典型的礁，其相带分异之清晰堪称为世界之最。北非突尼斯的礁也是研究程度较高的礁之一。中二叠世的礁以海绵、苔藓虫、Shamovella的大量出现为特征，古石孔藻、Shamovella和笛苔藓虫是常见的包覆生物。晚二叠世生物礁分布于欧洲镁灰岩统盆地、特提斯海西缘和最北缘的陆棚以及特提斯海域内的一些地体。我国晚二叠世礁十分发育，成为世界二叠纪礁的一个亮点。礁内的造架生物以珊瑚海绵为主，包括房室海绵和纤维海绵，古石孔藻和Shamovella (Tubiphytes)作为常见的包覆联结生物。

Main features of the Permian reefs of world and their palaeogeographic distribution

The Early Permian reefs in the world are distributed in the northwestern Pangean shelf, west slope of the Ural Mountains or eastern margin of the Russian Platform, the Permian Basin of North America and other localities. They occurred mainly in the former two areas. During the earlier period of Early Permian, the reefs were predominated by Palaeoaplysina or Palaeoaplysina-Phylloid algae, but to the later time of Early Permian, the reefs were replaced by Shamovella (Tubiphytes) and bryozoans as their framebuilders. The early Middle Permian (Qixian Stage) reefs are discovered only in the Glass Mountains of North America, Pamirs and Aerge Mountains in West China. The late Middle Permian (Maokouan Stage) reefs are regarded as the most well-developed reefs in the world. The Permian reefs of the Guadalupe Mountains become the most classic reefs which exhibit well distinct differentiation of sedimentary facies. The Middle Permian Tunisian reefs have been studied in details. The Middle Permian reefs are characterized by the abundant sponges, bryozoans and Shamovella (Tubiphytes) as their framebuilders, and Archaeolithoporella, Shamovella and fistuliporids as their binders. The Late Permian reefs in the world occur in the Zechstein Basin of West Europe, western marginal shelf and northern marginal shelf of the Tethys, and some terranes within the Panthalassen ocean. The Late Permian reefs are well developed in South China, which constitutes a bright spot in the distribution of the world Permian reefs. These reefs are characterized by coralline sponges, including the sphinctozoans and inozoans as their framebuilders. Archaeolithoporella and Shamovella (Tubiphytes) are usually formed as encrusting and binding organisms.