黔南克脚二叠纪末生物群特征及其地质意义

End-Permian Biotic Assemblage of Kejiao,Southern Guizhou and Its Geological Implications

贵州惠水克脚剖面是南盘江盆地北缘二叠系-三叠系界线剖面,地层连续,产不同门类的化石,对古生代-中生代之交黔南古地理和生物演化研究具有重要意义。剖面主要包括上二叠统大隆组和下三叠统大冶组下部。大隆组岩性主要为硅质泥岩、钙质泥岩和炭质页岩,夹火山灰黏土岩与薄层硅质灰岩,泥岩发育水平层理。大隆组主要产游泳生物菊石、浮游生物放射虫,另外产小个体腕足类、双壳类和腹足类等,少数层位含植物化石。大冶组下部主要为薄层泥质灰岩夹钙质泥岩。通过岩性、古生物组合、沉积构造等分析,认为本剖面在二叠纪末为离古陆较近的深水沉积。

The Permian-Triassic boundary section of Kejiao, southern Guizhou is located in a deep-water fa- cies in the northern part of Nanpanjiang Basin. The section includes the Upper Permian Dalong Formation and the basal part of Lower Triassic Daye Formation. The Dalong Formation is mainly composed of sili- ceous mudstone, calcareous mudstone and carbonaceous shale, intercalated with volcanic ash and siliceous limestone, with horizontal bedding in mudstone. The basal part of the Daye Formation is mainly composed of thin-bedded argillaceous limestone, intercalated with calcareous mudstone. The biotic assemblage of the Dalong Formation is dominated by nektonicammonoids, and planktonic radiolarians, associated with a few small-sized brachiopods, bivalves and gastropods, and sparsely with a few plant fossils （transported from terrestrial facies）. It is suggested that the Dalong Formation of Kejiao was deposited in a deep-water set- ting near the Kangdian Ancient Land, based on the analysis of biotic assemblage and sedimentary feature.