Jielongqiao Fm
Type Locality and Naming
It was named by the Regional Survey Party of Hunan Province in 1980. The naming section is located in the vicinity of Jielongqiao at Luyang, Huaihua County, Hunan Province, with its reference section being situated in the Xiajiarong area of Shimen County.
Synonym: （接龙桥组）
Lithology and Thickness
It is composed largely of sandy mudstone, siltstone and fine-grained sandstone, intercalated with a small amount of thin coal beds. Except for the conglomerate at its base, there are few coarse clastic materials inside of the strata. It is usually possessed of oolitic structure. Its lower part commonly bears grey-black color, and is turning upwards into grey-white color, its thickness being of 179 m.
Relationships and Distribution
Lower contact
Its basal part is in a disconformable contact with the underlying Xiaojiangkou Fm of Triassic (?) (but not yet in Triassic Lexicon; nor in China Strat-names book of Springer)
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Dahupo Fm
Regional extent
The formation is distributed essentially in the areas of Luyang, Huaqiao and Xiaolongmen of Huaihua County in northwestern Hunan. Southwesterly to the area of Feishan of Jingxian County the thickness of the formation is getting smaller; while northerly to Cili, Shimen and Lixian Counties the formation is getting thicker. The total thickness of its strata varies in a range from 88 m to 378 m.
GeoJSON
Fossils
In the Xiajiarong section of Shimen County, the formation yields bivalves as represented by Lilingella simplex, Qiyangia fortis, Pseudocardinia sp., Apseudocardinia sp.; while in the Luyang and Huaqiao sections of Huaihua County it yields plant fossils as represented by Todites denticulate, Dictyophyllum nathorsti, D. nilssoni, Marattiopsis sp., Pterophyllum ptilum, P. nathorsti, Anomozamites cf. minor, and Otozamites sp., as well as spore-pollen fossils.
Age
Depositional setting
The formation belongs to fluvial-lacustrine and swamp-facies coal-bearing deposits.
Additional Information