Dahuanggou Fm
Type Locality and Naming
The type section is located at Dahuanggou 50 km to the southwest of Jiuquan City, Gansu Province. It was named by Sun Jianchu in 1936.
Lithology and Thickness
Clastics. Composed chiefly of grey-green, yellow-green sandstone, fine-grained sandstone, sandy siltstone, medium-grained and coarse-grained sandstone, intercalated with sandy siltstone and a small amount of black siliceous siltstone, with its top part consisting of grey-white and light-grey-green pebble-bearing coarse-grained sandstone. Thickness is 353 m.
Relationships and Distribution
Lower contact
Conformable contact with the underlying Shanxi Fm
Upper contact
Between it and the overlying Yaogou Fm there might exist a break.
Regional extent
Distributed in the North Qilian Mt. area extending from Yumen in the west and to the slope of Liupan Mt. in the east, comprising the Hexi Corridor. In the Daqing Trench of South Gansu the thickness of the formation reaches as great as 297 m, composed mainly of light-red sandstone, and conglomeratic layers, with its top part containing purplish-red pebble-bearing sandstones, part of which may probably belong to the Yaogou Fm, with its thickness reaching as great as 244 m at Hejia Mt. of Tongwei County
GeoJSON
Fossils
Plant fossils: phytolites such as Lepidodendron sp., Sphenophyllum cf. thonii, Annularia sp., Pecopteris cf. polymorpha, Alethopteris norinii, Taeniopteris cf. multinervis, etc.
Age
Depositional setting
It is interpreted as a river-lake facies deposit.
Additional Information