扬子区奥陶纪、志留纪四射珊瑚分类、生物地层与生物古地理新认识

Recognition of the classification, biostratigraphy and biogeography of the Ordovician and Silurian rugose corals in the Yangtze Region

对扬子区中奥陶世至晚志留世四射珊瑚已发表的属种进行全面清理和厘定。现统计扬子区中奥陶世至晚志留世四射珊瑚约有117个属,其中以晚奥陶世和早志留世珊瑚属数最多。117个属中至少有30个属最早出现在扬子区中、晚奥陶世和早志留世地层。因此,扬子区被认为是奥陶纪、志留纪四射珊瑚起源中心之一。完善和修订扬子区中奥陶世至晚志留世四射珊瑚组合序列,使地层时代划分上均与国际通行标准(统、阶)接轨。尤其对扬子区早志留世Rhuddanian晚期,Aeronian早、晚期以及Telychian早、晚期四射珊瑚组合的重新建立和细分。最新资料表明晚奥陶世观音桥四射珊瑚动物群不但有更多的北欧同期的珊瑚分子,而且还产有北美标准属种Salvadorea,Brachyelasmasubregulare等说明两者也存在一定的联系。扬子区早志留世(Llandovery)的众多四射珊瑚属均为世界广布的,但也有许多地方性属(约有22个,占总数的23·4%)。就珊瑚生物古地理关系,它与同期的西伯利亚、哈萨克斯坦和澳大利亚珊瑚群较密切。

In the present paper all genera and species known of the Ordovician and Silurian rugose corals in the Yangtze Region,are systematically collated, and 117 genera are considered to be valid. Most of them are Late Ordovician and early Silurian corals with the highest diversity all over the world. In the Ordovician and Silurian rugose corals fauna more than 30 genera are known to occur earliest in the Yangtze Region during Middle Ordovieian-Early Silurian. For this reason the Yangtze Region can be regarded as one of the origin centers of Ordovician and Silurian rugose corals, which improves and redefines the sequence of the Ordovician and Silurian rugose coral assemblages in the Yangtze Region, and makes the choronostratigraphie subdivision be concordant with the international standard of stratigraphy. The rugose coral assemblages are further subdivided into the Late Rhuddanian, Early Aeronian, Late Aeronian, Early Telychian and Late Telychian in the Yangtze Region. Based on recent investigation,the rugose corals bore in the Guanyinqiao Bed not only contain more North Europe elements, but also some typical genera and species, such as Salvadorea ,Brachyelasma subregulare immigrating from North America are found in the bed. It indicates that the Guanyinqiao Bed rugosan fauna has a certain relation to those of North America. In the Yangtze Region, numbers of Llandovery rugose genera were cosmopolitan, but comprising many endimics（about 22 genera, 23.4%）, some of them first appeared in the Yangtze Region and later dispersed to other regions. In biogeographic affinity, the Landovery rugose fauna in the Yangtze Region is much closer to that in Siberia, Kazakhstan and Australia.