Huadian Fm

The naming section is located at Gonglangtou and Daboji ~15 km northeast of Huadian County, Jilin. Named by Nishita Shouichi in 1940.

This formation may be divided into three parts: Lower part, yellowish brown or gray sandstone and pebbly sandstone with carbonaceous shale; Middle part, yellowish brown sandstone with variegated sandstone and mudstone, with several beds of minable oil shale; Upper part, grayish white, grayish green and gray pebbly sandstone, sandstone, muddy sandstone and sandy mudstone, with oil shale and lignite beds. The outcrops are generally poor, mainly found in the wells; the thickness reaches 1600–1900 m.

Fossils of the Huadian Formation are only found in its middle and upper parts. In addition to plants, gastropods and Threskiorothidae and Anatidae of birds, the fishes are mainly Amia, Catostomidae and Clupeiformes, and the mammals mainly include Eochenus sinensis, Tupaiodon huadianensis, Ernosonex jilinensis, Asiomomys changbaicus and Zelomys orientalis.

According to the fauna, flora and sediments, the ecological environment of Huadian then was of forest-swamp-lake facies. A number of animals living in tropical and subtropical jungles appeared; meanwhile, there were numerous fishes and hydrophilic birds.