Dongxuanguan Fm
Type Locality and Naming
Its type section is located on the Fangshan hill (E118°52′, N31°55′), Jiangning District of Nanjing City, Jiangsu Province. It is derived from the “Dongxuanguan Bed” named by Cheng and Shen (1948), which was formally promoted into formation at the First National Stratigraphic Conference in 1959 (See Pei et al., 1963).
Synonym: Bi et al. (1977) proposed that the Puzhen Fm named by Li and Fang (1964) is a synonym of the Dongxuanguan Fm. BGMRJ(Jiangsu)P (1984) treated the Xiaocaowan Fm distributed to Sihong and Xuyi area as a synonym of the Dongxuanguan Fm. Up to now, the Xiacaowan Fm and the Dongxuanguan Fm are normally accepted as separated formations (BGMRJ(Jiangsu)P, 1997; Zheng et al., 1999; Gao et al., 2014a).
Lithology and Thickness
Bureau of Geology and Mineral Resources of Jiangsu Province (BGMRJ(Jiangsu)P) (1997) redefined the lithology of this formation. The Dongxuanguan Fm is a series of rhythmic deposits mainly formed by yellowish-brown gravels and fine sandstones, yellowish-brown and greyish-white silty clays with calcareous nodules. It contains mammalian fossils. Its thickness is in range of 14.5 to 63 m.
Relationships and Distribution
Lower contact
In the type section, the Dongxuanguan Fm conformably contacts with the underlying Cretaceous Chishan Fm. Regionally, the next older unit is the Shanghuangliexi Fm (middle Eocene) then the Paleocene Shuangtasi Fm.
Upper contact
In the type section, the Dongxuanguan Fm conformably overlain by the FangshanBasalt Fm.
Regional extent
This formation is widely distributed to region ranging Jiangning, Liuhe, Xiaopanshan, Fangshan, Renjiaju, Huanggang, Chenxiangying, and Xuyi, Jiangsu Province.
GeoJSON
Fossils
Fossils from Fangshan: (see Chow and Hu, 1956; Li, 1977): Mammals: Anchitherium aurelianense, Spanocricetodon ningensis. Fossil remains from Puzhen: (see Li and Fang, 1964; Chow and Wang, 1964; BGMRJ(Jiangsu)P, 1984; Li et al., 1987). Mammals: ?Listriodon sp., Brochypotherium cf. B. aurelianense, cf. Stephanocemas colberti, Dicrocerus cf. D. elegans Fish: Pisces indet. Reptilia: Emydas indet., Trionyx sp., Alligator sp. Plants: Leguminosites climensis, Leguminosites sp., ?Albizzia miokarkora, ?Gymnocladus miochinensis, Entada mioformosana, Podogonium oehningense Bivalves: Hyriopsis nana, Modiolus sp. Gastropods: Gyraulus sp., Valvata sp.
Age
Depositional setting
It is interpreted as a river-lake environment.
Additional Information