Xinyu Gr

The naming section is located near Ningjiashan, Yaoxu Township, ~5 km south of Huanggang, northeast of Xinyu City, Jiangxi. Named by the Jiangxi Bureau of Geology in 1959.

Lower member (Ningjiashan Member) is mainly purplish red or grayish purple muddy sandstone, pebbly sandstone and sandy mudstone, with grayish green or grayish white sandstone, containing calcareous concretions. Upper member is variegated (coffee, purplish red, grayish yellow, grayish black and gray) mudstone and sandstone. According to the well logs, the lithology of this formation is highly varied: the sediments are relatively fine west of the Ganjiang River and in the basin center and become relatively coarse on the southern margin of the basin; the formation generally contains saline deposits such as gypsum and mirabilite. The thickness is about 600–1000 m.

The lower member of this group contains Amia, crocodiles and turtles, as well as mammals such as Coryphodon ninchiashanensis, Prodinoceras sinyuensis (=Probathyopsis ?sinyuensis), Xinyuictis tenuis and Heptodon (?) sp.; the upper member mainly contains the charophytes Grovesichara, Neochara and Nemegtichara, the gastropods Bithynia, Physa and Australorbis and the ostracods Cypris, Eucypris, Limnocythere and Candona. The above-mentioned assemblage basically reflects the Eocene feature; especially the mammal fossils found in the lower member may essentially correlate with their early Eocene Wasatchian analogues in North America. Furthermore, according to studies of the sporopollen assemblages of He Yueming and Sun Xiangjun (1977) and Wang Daning (1984), Pterisisporites, Ephedripites, Psophosphaera, Rhoipites and Proteacidites in this horizon occupy an important position in this assemblage. This feature reflects that the climate at that time was a relatively dry subtropical one.

Fluvio-lacustrine deposits dominated by fine clastic rocks.