Longyin Fm
Type Locality and Naming
The type section is located in the area of the Longyin Village 28 km to the east of the Pu’an County Town, Guizhou Province. It was named by the Guizhou Regional Geological Reconnaissance Party in 1973.
Lithology and Thickness
Clastics and Limestone. Interbedded yellow-brown siltstone, medium- and thick-bedded quartz-sandstone, micrite and marl. It is divisible into two parts as follows: Lower part is composed of brown, grey-brown and black clayey and sandy shales, intercalated with a small amount of quartz-sandstone and clayey limestone. Upper part is composed of yellow-brown quartz-sandstone, siltstone, claystone and carbonaceous shale. The basal part of the formation is composed of dark-grey and black thin-bedded siltstone, intercalated with micrite. Thickness is 250-300 m.
Relationships and Distribution
Lower contact
Conformable contact with the dark-grey and grey medium- and thick-bedded micrites on the top of the underlying Shazitang Fm
Upper contact
Conformable contact with the dark-grey thick-bedded micrite and bioclastic limestone at the base of the overlying Baomoshan Fm
Regional extent
Distributed in the areas of the Panxian, Liuzhi, Pu’an and Qinglong Counties, with the limestone tending to increase in amount southerly to change physically to the Maping Fm.
GeoJSON
Fossils
In the Longyin area it yields Fusulinida fauna represented by Sphaeroschwagerina glomerosa, Pseudofusulina moelleri, as well as Ammonoid fauna represented by Popanoceras.
Age
Depositional setting
It is interpreted as a shallow-sea facies deposit.
Additional Information
GeoJSON estimate by Can Cai and Xinyi Zhang (Chengdu Univ. Tech. students)