Baoan Fm
Type Locality and Naming
The type section is section is located in the area of Bao’an to the west of Huangshi City, Hubei Province, and the reference section is situated by the roadside of the Xiayao Highway, Huangshi City, Hubei Province. It was named by Xie Jiarong in 1924.
Synonym: Bao'an Fm
Lithology and Thickness
Shale. Mainly dark-grey thin-bedded siliceous shale, intercalated with banded siliceous layers, with its basal part being intercalated commonly with brown-yellow sandy shale. Its total thickness is of 10-30 m.
Relationships and Distribution
Lower contact
Conformable contact to Longtan Fm. Its base is different from the Xiayao Limestone in the upper part of the Longtan Fm.
Upper contact
Conformable contact to Daye Fm. Its top part is marked by the occurrence of yellow-green siltstone of the Daye Fm serving as a dividing boundary.
Regional extent
The formation is distributed in the areas of the middle and lower reaches of the Changjiang River, with a fairly stable lithology. Below it there occurs the Xiayao Fm known popularly as the “Coal-pressing Limestone” in the Jiangsu and Anhui Provinces, while above it there occurs the Qinglong Fm; being in a conformable contact with both its underlying and overlying strata in various places.
GeoJSON
Fossils
Ammonoids represented by Pseudotirolites, Pseudogastrioceras, Retiogastrioceras, etc.
Brachiopods represented by Cathaysia chonetoides, Waagenites barusiensis and Neowellerella pseudoutah.
Age
Depositional setting
It is interpreted as deep-water basin-facies deposits.
Additional Information