Nongshan Fm

The naming section is located at Luozhai Village-Nongshan, Hukou Township, 11 km northeast of Nanxiong County, Guangdong; the reference section is located at Datangxu and Pingling-Gucheng, Youshan Township, 30 km northeast of Nanxiong County, Guangdong. Named by Zhou Mingzhen in 1973.

The Zhuguikeng Member (Lower member) is purplish red and brownish red sandy mudstone with grayish green calcareous mudstone and pebbly sandstone lenses, 113 m thick; the Datang Member (Upper member) is composed of purplish red and brown red sandy mudstone and siltstone, with thin beds or bands of pebbly sandstone or sandy conglomerate, 241 m thick. The lithology and thickness of the formation vary somewhat from place to from: at Dengfang the rocks become coarse and at Hukou the formation becomes thin and generally >200 m thick.

The formation contains abundant fossils of various groups, including ostracods, gastropods, Estheria, fossil tubes charophytes and other plants, as well as turtles, crocodiles and mammals. The mammals have at least 10 families, 13 genera and 18 species, mainly including Ernanodon antelios, Haltictops mirabilis, Yantanglestes datangensis, Minchenella granchis, Yuelophus validis and Archaeolambda zhuguikengensis and Notoungulata. Ostracods include 10 genera and 14 specise, such as Sinocypris funingensis, Eucypris sanzhuiensis, Parailyocypris changzhouensis and Cyprois buxinensis. Gastropods are represented by the Polycircus gracilicostata-Nanxiongospira uniptychia assemblage. The genus and species of Estheria are monotonous, being only Paraleptestheria menglaensis. Charophytes are abundant, including 17 genera and 51 species, such as Grovesichara changzhouensis, Peckichara varians and Gobichara deserta. Plants are mainly Palibinia pinnatifida etc. Fossils found in South China and northern China in recent years indicate that during the early Paleocene there was almost no same or common genus between Asia and other continents, and that there is no marked sign of direct exchange. In some middle Paleocene horizons such as the Nongshan Formation, however, there are a few genera and species similar to those of Europe and America. This indicates that the state of isolation in the early Paleocene changed somewhat in the Asian continent and Europe and America. What is interesting is that edentates and notoungulatas that predominate in South America are found in the Nongshan Formation. They as special forms in the Neotropical realm are always of very restricted distribution. Because of the discovery of these fossils, their origin, time of occurrence and intercontinental connection are difficult to explain in light of traditional zoogeographic knowledge.

The formation is lacustrine deposits.