Guanyintan Fm
Type Locality and Naming
The type section is located in the vicinity of the Guanyintan Township, Qiyang County, Hunan Province. It was named by No. 3 Coal Prospecting Party of Hunan Province in 1974, and was first cited publicly by Chen Jinhua in 1980.
Synonym: （观音滩组）
Lithology and Thickness
It is divisible into three members: Paijiachong Member representing grey-violet and grey-black fine-grained sandstone and siltstone, intercalated with shell mudstone and clastics, with a thickness of about 137 m. Taba Member consisting of brown-yellow, light-grey and grey-black feldspar-quartz sandstone, siltstone and mudstone, intercalated with coal beds, coal seams, lenticular limestone and biotic shell clastics, with a thickness of 203 m. Fengjiachong Member representing variegated silty mudstone and siltstone, intercalated with pebble-bearing coarse-grained sandstone, with a thickness of about 157 m. Its thickness is of 497 m.
Relationships and Distribution
Lower contact
Its basal part is in a disconformable contact with the underlying upper Triassic Yangbochong 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 Shixijiang Fm
Regional extent
It is distributed essentially in the Lingling-Qiyang area, Hunan Province, forming an overlapping deposition in a direction from southeast to northwest.
GeoJSON
Fossils
It yields bivalve and plant fossils. The bivalves are represented by Lilingella xinyuensis-Hunanella shijiabaensis assemblage. There are found in the formation 20 genera and more than 30 species of Gastropoda, including Neridomus cannalis, Oonia morencyana and Pachychilus amalthei. It yields also Ostracoda, insect and fish fossils. There are more than 33 genera and 72 species of plants, belonging to the Marattiopsis-Otozamites assemblage of Cictyophyllum- Clathropteris flora; with the spore-pollens being represented by the Classopollis- Cerebropollenites-Klukisporites assemblage.
Age
Depositional setting
The formation belongs to paralic-plain and lacustrine-swamp facies associated with desalted gulf-facies or lagoonal deposits.
Additional Information