Shuangtasi Fm
Type Locality and Naming
The naming section is located in the vicinity of Yangongqiao-Shuangtasi west of Xuancheng City, Anhui, and the reference section is located at Luosigang and other places ~12 km east of Xuancheng. Named the Shuangtasi Group by the Anhui Regional Geological Survey Party in 1974.
Synonymy: Shuangta Fm
Lithology and Thickness
Lower part is purplish red conglomerate, no fossil being seen. Middle part, purplish red, muddy sandstone and sandy mudstone with grayish yellow, grayish white and yellowish green sandstone. Upper part is purplish red or brownish red, pebbly sandstone, sandy mudstone and mudstone. The thickness is ~200–760 m.
Relationships and Distribution
Lower contact
The formation has a disconformable or unconformable contact (?) with the underlying Upper Cretaceous.
Upper contact
Regional extent
It is distributed at Gucun, Shuangtasi, Yusantang, Luosigang and Magushan in the suburbs of Xuancheng City. According to the data, similar horizons are also exposed at Wuhu, Nanling and other areas along the Yangtze River of Anhui Province.
GeoJSON
Fossils
The fossils of the Shuangtasi Formation are restricted in its middle and upper part. The mammals mainly include Hsiuannania maguensis, Archaeolambda yangtzeensis, Dissacus magushanensis and Bothriostylops progressus; ostracods are marked by an assemblage represented by Sinocypris funingensis, Neomonoceratina bullata and Cypris decaryi; the gastropods are represented by the Multiscapta rara-Ganeselloides sulcatus assemblage; and charophytes are represented by such genera and species as Peckichara anhuiensis, Grovesichara changzhouensis and Neochara huananensis.
Age
Depositional setting
It is generally considered that the formation is fluvial-lacustrine deposits.
Additional Information