Chijiang Fm

The naming section is located at Xincunli, Lannikeng and Wangwu, Chijiang, >20 km northeast of Dayu County, southern Jiangxi. Named by Zheng Jiajian, Tong Yongsheng et al. in 1973.

Based on the lithology and biotas two members may be distinguished. Lower member (or called the Lannikeng Member) consists of purplish red mudstone and muddy sandstone with grayish green conglomerate. Upper member (or called the Wangwu Member) is comprised of purplish red mudstone with grayish red, brick-red and grayish green sandstone and mudstone. Generally speaking, its lithology is coarse in the western part of the basin and becomes fine and rich in calcareous matter toward the east. The total thickness is ~360–500 m.

There are at least 12 species of mammals in the lower member, which are mainly Archaeoryctes notialis, Hsiuannania minor, Archaeolambda cf. palanicana, Harpyodus decorus and Asiostylops spanios; the mammals in the upper member include four species, which are Jiangxia chaotoensis, Archaeolambda sp., Allostylops periconotus and Bothriosylops notios. The ostracods are dominated by Sinocypris excelsa, and the common genera are Eucypris, Cypris, Parailyocypris and Cyprois. Gastropods are Nanxiongospira nobilis etc. Charophytes consist dominantly of Peckichara longa, and the common genera are Stephanochara, Obtusochara, Neochara and Gyrogona. The sporopollen is represented by the Pteris-Ulmus assemblage. Generally the pollen of angiosperms in the lower member accounts for 65.6%, while gymnosperms have a low content. In the upper member the pollen content of gymnosperms is increased markedly, making up 30.2%, of which the content of Ephedra is relatively conspicuous. What is most interesting in the biotas of the Chijiang Formation is the discovery of some fossils of primitive and old Notoungulata. This order is a endemic group in South America. The discovery of the old form of this group in southern China has great significance for the study and understanding of the zoogeographic relations between the Asian, North American and South American continents at the beginning of the Paleogene.

It is lacustrine deposits,