新疆北部泥盆纪床板珊瑚组合特征兼论下、中泥盆统的划分

<正> 新疆北部阿尔泰山、东、西准噶尔及北天山地区,下、中、上泥盆统皆有床板珊瑚,垂直变化明显,形成了自奥陶纪以来第三个繁盛期。本文将本区泥盆纪床板珊瑚分布规律及其组合特征介绍如下:

The Devonian tabulate coral assemblages of northern Xinjiang with remarks on subdivision of the Lower-Middle Devonian

During the past two decades, a large number of Devonian tabulate corals were gathered from many localities in northern Xinjiang. On the basis of study on these corals, five Devonian coral assemblages of northern Xinjiang are established as follows: Upper Devonian: Aulopora-Striatopora Assemblage; Middle Devonian: Alveolites-Trachpora Assemblage, Pachyfavosites polymorphus-Tyrganolites-Xinjiangolites Assemblage; Lower Devonian: Squameofavosites-Placo-coenites-Pseudofavosites Assemblage, Aulocystis-Steatothamnopora-Pleurodicttyum Assemblage. In the light of the tabulate coral assemblages mentioned above, the author suggests that the Lower Devonian of marine fades may be subdivided into two parts, namely, the Utubulake (including Mengeer) and Taheierbasitaw (or Asushan) Formations in the lower part; the Mong-kelu, Zuomubasitaw (or Tuoranggekuduke) and Dananhu Formations in the upper. The Middle Devonian may be also subdivided into two parts, namely, the Kulumudi (or Sawuershan), Altai, Wulusubasitaw (or Beitashan) and Baixinde Formations in the lower part; the Zhifang Formation in the upper. The author also suggests that the first occurrence of Pachyfavosites polymorphus, Tyrganolites, Xinjiangolites is con sidered as the beginning of the Middle Devonian.