Maotanchang Fm
Type Locality and Naming
Heifei Basin, south zone. The Maotanchang Formation was erected by Yang Zhijian in 1959. The section for the designation is from Dajimingling to Gaobeilou about 40 km south of the Liuan County of Anhui.
Lithology and Thickness
The Maotanchang Formation is represented by grayish green and gray thick-bedded andesitic tuff, tuff breccia and breccia agglomerate with several beds of purple red medium- thin-bedded tuffaceous sandstone, with an increase of lava upward. It is 632 m thick.
Relationships and Distribution
Lower contact
In the type section, its base marked by andesite lies disconformably on gneiss granite of the underlying Xiaoxihe Fm of Sinian. Regionally, the next older unit are the Fenghuangtai Fm conglomerates of late Jurassic-early Cretaceous
Upper contact
Its top marked by andesite lies disconformably under the Baidaban Fm marked by trachyandesitic volcanic rocks.
Regional extent
The formation occurs in the Huoshan-Jiujing basin and the Mozitan-Xiaotian basin. In the Huoshan and Jiujing areas it is represented by tuffaceous breccia, tuff and tuffaceous sandstone alternated with clayey silt and calcareous mudstone. Westward from Xiaotian to the Jinzha County, it is dominated by intermediate volcanic rocks. In Lingbi, Shuzhou and Guzhen of Hubei, it is dominated by moderately basic volcanic rocks. It is 500-1500 m thick at the center of the basin and 150-500 m on the margin of the basin.
GeoJSON
Fossils
In Xiaotian of Shucheng and in Chupiling of Huoshan, it yields bivalves Ferganoconcha lingyuanensis, Carbicula, Sphaerium jeholense; gastropod Probaicalia sp.; estheria Eosestheria sp.
Age
Depositional setting
It is marked by volcanic deposition with lake-shore facies.
Additional Information