Yangxi Fm
Type Locality and Naming
Jianghan Basin - NW. The type section is located at Laoyashan ~2 km west of Yangxi Township, southeast of Yidu County, Hubei, and the reference section is located at Gongjiachong, Dangyang County-Baiquesi, Zhijiang County. It was named by P.T. de Chardin and C.C. Young in 1935–1936.
Lithology and Thickness
Lower part is brownish yellow, brownish red, purplish red and yellow green sandstone and muddy sandstone and sandy mudstone with grayish white or grayish yellow sandstone and marlstone, containing calcareous concretions, the base of which is light brown sandy conglomerate and conglomerate with sandstone. Upper part consists of grayish purple, purplish red, grayish white and brownish red limestone and marlstone, with brownish red, grayish black and grayish green muddy sandstone, the base of which is brownish yellow or brownish red sandy mudstone and grayish green mudstone with purplish red or grayish purple marlstone. The thickness is about 100–150 m and ranges from about 100 to 520 m to the east of Songcikou and at Dongyuemiao, Dangyang.
Relationships and Distribution
Lower contact
The formation has a conformable or disconformable contact with the underlying Paomagang Fm.
Upper contact
The formation has a conformable or disconformable contact with the overlying middle Eocene Pailoukou Fm.
Regional extent
It is mainly distributed at Yidu, Songzi and Dangyang, and similar horizons are probably exposed at Nanzhang and Jingmen.
GeoJSON
Fossils
The formation contains abundant fossils. The ostracods are represented by the assemblage mainly of Cypris-Limnocythere-Sinocypris; the gastropods are Bithynia lordostoma, Australorbis odhneri etc. The vertebrates mainly include fishes, birds (Songzia heidangkouensis) and the mammals Coryphodon zhichengensis and Asiocoryphodon cf. conicus. In addition, there are the charophyte fauna mainly of Peckichara-Grovesichara and sporopollen.
Age
Depositional setting
This formation refers to lacustrine deposit.
Additional Information