Sunan Fm
Type Locality and Naming
The type section is located at Daqinggou of Sunan County, Gansu Province, and is corresponding approximately to the 5th and 6th beds of the section established by Bexell G. (1935). It was named by Liu Hongchou and Shi Meiliang in 1980, and was cited publicly by the Bureau of Geology and Mineral Resources of Gansu Province in 1988.
Lithology and Thickness
Sandstone. Composed mainly of purple and light-grey-green sandstone and fine-grained sandstone, intercalated with black shale, with its base consisting of grey extremely thick-bedded conglomerate and pebbled sandstone. Thickness is 180 m.
Relationships and Distribution
Lower contact
Disconformable contact with the underlying Yaogou Fm
Upper contact
Unconformable contact with the overlying Lugou Fm of the Lower Triassic
Regional extent
In the area of Yanglu River this formation is composed mainly of grey-green clastic rocks, with the purple clastic rocks decreasing in amount, and with its thickness being of 408 m.
GeoJSON
Fossils
Yields such Plant fossils (phytolites) as Paracalamites tenuicostata, Phyllotheca deliquescens, Annularia gracilescens, Lobatannularia sp., Pecopteris tenuicostata, Prynadaeopteris anthriscifolia, Zamiopteris glassopteroides, Z. lanceolata, Iniopteris sibirica, Psygmophyllum multipartitum; bivalves and spore-pollen, etc.
Age
Depositional setting
It is interpreted as river-lake facies deposits.
Additional Information