浙江江山大隆组古生物群特征及二叠系与三叠系界线

<正> 浙西北的长兴阶有二种沉积类型,即碳酸盐岩相的长兴组和硅泥质岩相的大隆组。长兴组的层位和生物群分带。前人已作过较详细的研究,而浙西江山大隆组的生物群至今未

Palaeontologic characters of the Dalong Formation of Jiangshan, Zhejiang and the boundary between the Permian and Triassic

A large number of fossils were collected from the Dalong Formation of Jiangshan, western Zhejiang. They are represented by abundant plankton and cpiplankton, including cephalopods Pseudotirolites asiati-cus, Pleuronodoceras sp., Pseudogastrioceras sp., Huaranoceras spp., Mingyuexiaccras? sp., Lopingoceras sp., brachiopods Paryhella sp., Lingula spp., Orbiculoided elegans, Crurithyris sp., Ncowcllerella tripli-cata and bivalves Hunanopecten exilis, Pernopecten sp.. These fossils are associated with Essheria, which is first found in the Dalong Formation of South China. Some of them are new species. Based on the characters of the above fossils, the Dalong Formation can be correlated with the Meishan Member of the Changxing Limestone in northern Zhejiang. As most areas of South China, the Permian and Trias-sic Systems are also a continuous sequence in this region. The boundary between the Permian and Trianssic is at the base of Hypophiceras-bearing beds. Hypophiceras fauna cooccurs with a mixed fauna consisting of typical Mesozoic elements, including Metophiceras sp., ophiceratids, Pseudosageoceras.sp. Eumorphotis sp. and Polygryina sp., Orbiculoidea qinglongensis, Cryrithyris spp. and Pseudogastrioceras sp.. It is of important significance that the mixed fauna occurs below the beds containing Claraia wangi.