湖北省下三叠统牙形石生物地层序列与研究展望

Lower Triassic Conodont Bio-stratigraphic Sequence ofHubei Province and Research Prospect

早三叠世是二叠纪—三叠纪之交生物大灭绝之后重要的生态系统复苏期,同时期湖北省沉积了大量的海相大冶组和嘉陵江组地层,其中保存了许多世界罕见的古生物化石,包括黄石地区的裂齿鱼以及南漳—远安地区的海生爬行动物群等,是理解复苏过程的重要研究窗口之一。作为古、中生代之交最重要的标准化石,牙形石可以为高分辨率生物地层对比提供依据。对前人在湖北省进行的早三叠世牙形石的研究进行系统性总结,为该省下三叠统的详细年代地层划分提供生物依据。当前,湖北省下三叠统可以建立16个牙形石带,根据这些牙形石带,将湖北省下三叠统各亚阶(格里斯巴赫亚阶、迪纳尔亚阶、史密斯亚阶、史帕斯亚阶)的底界均限定在大冶组。这也表明以白云岩、角砾岩、灰岩为主体的嘉陵江组主要沉积于早三叠世史帕斯亚期。相较之下,嘉陵江组厚度往往比大冶组更大,但其内部牙形石带的研究成果却近乎匮乏,因此未来也需加强对湖北地区嘉陵江组牙形石生物地层序列的研究。

The Early Triassic was a key interval for the ecosystem recovery after the Permian-Triassic mass extinction.A large number of marine Daye Formation and Jialingjiang Formation were deposited in Hubei Province,which preserved many rare paleontological fossils in the world,including Plesioperleidus in Huangshi area and marine reptiles in Nanzhang-Yuan'an area.It is one of the important research windows to understand the recovery process.As the most important standard fossil at the turn of Paleozoic and Mesozoic,conodonts can provide a basis for high-resolution biostratigraphic correlation.This study summarizes Early Triassic conodont studies of Hubei Province of recent decades,which helps us to understand the divisions the Lower Triassic of Hubei Province.According to the reported sixteen conodont zones from the Lower Triassic of Hubei Province,bases of the Griesbachian,Dienerian,Smithian,Spathian can be verified at different members of the Daye Formation,which further indicates that dolostone,breccias,limestone of the Jialingjiang Formation were mainly deposited during the Spathian.In contrast,the Jialingjiang Formation is usually thicker than the Daye Formation.However,conodont has been rarely reported from the Jialingjiang Formation.Hence,conodont bio-stratigraphic research of the Jialingjiang Formation from Hubei province is needed in the future.