Wutu Fm

The naming section is located at Laowanggou and other localities 10 km southeast of Changle County, Shandong and the reference section is based on cores taken from various wells in Wutu coal mine ~1 km southeast of Changle County. Named by the No. 121 Party of Shandong Coal Administration in 1960 and formally used in 1965 (Zhou Mingzhen and Li Chuankui, 1965).

The formation is generally divided into three members: Lower part is dark gray, grayish black, grayish green, purplish red and gray conglomerate and sandy conglomerate with sandstone and sandy mudstone. Middle part is gray or grayish green sandstone and sandy mudstone with brownish yellow oil shale, gray marlstone and coal beds, the base of which is conglomerate and sandy conglomerate. Upper part is grayish white, grayish green and purplish red sandy mudstone and mudstone alternating with grayish or yellowish white sandstone and marlstone, intercalated with carbonaceous shale and coal beds, the base of which is sandy conglomerate. Generally the lithofacies varies greatly. The thicknesses of the coal and oil shale beds increase from west to east and the lithology becomes coarse from south to north. The formation consists of clastic rocks and claystone, bearing no coal or oil shale, at Fushan of Weixian, Dongjia of Weifang, Lijiabu of Anqiu and north Tangwu of Changle. It is up to 1200 m thick in the vicinity of Wutu, >300 m thick at Niushan and Luojiashu of Linqu, and ~130–350 m thick at Maobu of Juxian.

The Wutu Formation contains abundant fossils, especially gastropods and mammals. The gastropods include 18 species, of which at least 7 species are present in the middle Eocene Guanzhuang Formation in Shandong, mainly Dimorphoptychia speciosa, Palaeoleuca sniensis, Physa shantungensis and Pupoides antiquus. Vertebrates are Changlosaurus and Anosteira; mammals include Homogalax wutuensis, Changlelestes dissetiformis, cf. Altanius sp. and Alagomys sp., as well as Notoungulata and Edentata. In addition, there are ostracods such as Eucypris reniformis, E. wutuensis and Candoniella albicans.

Fossil mammals such as Homogalax were only found in the lower Eocene in the past. As these early-stage tapirs appeared in Shandong and Mongolia, some geologists infer that these forms similar to those of North America possibly evolved from related groups of Asia. The above-mentioned phenomenon also suggests that the early Eocene faunas in Asia and North America were relatively close. The interchange of animals through the Bering continental bridge between the two continents was relatively active.

According to the study of sporopollen by Song Zhichen et al. (1964), the flora is of forest nature. Dominated by needle leaf plants, mixed with plentiful deciduous and broadleaf plants to form mixed forests. The paleoclimate is of warm-hot and wet subtropical type.