Dunzigou Gr
Type Locality and Naming
Central Gansu. The Dunzigou Gr was named by the No. 1 Party of Regional Geological Sur-vey, Gansu Bureau of Geology in 1967. The type locality Dunzigou is on North Slope of Hanmu Mt., Yongchang County, Gansu Province.
Synonym: （墩子沟群）
Lithology and Thickness
The Dunzigou Gr is composed of terrigenous-clastics and Si-Mg-rich carbonate association of littoral-neritic facies. The group is subdivided into three lithodem sets. Lower set is composed of purple-red grey-white feldspar-quartz sandstone, pebbly coarse sandstone, conglomerate, 64-500 m thick. Middle set is blue-grey siliceous limestone, 500-1200 m thick. Upper set, 150 m thick, consists of grey-green phyllite intercalated with chert-banded limestone and quartzite. The total thickness varies from 700 to 2000 m.
Relationships and Distribution
Lower contact
The base is in unconformable contact with the underlying Longshoushan Gr (schist and gneiss).
Upper contact
Overlain disconformably or unconformably by the Hanmushan Gr (Shaohuotonggou Fm) of the Neoproterozoic (column 15 of Neoproterozoic).
Regional extent
Central Gansu. Concentrically distributed in Longshou Mt., the Dunzigou Gr is thinned, even pinched out, to the west, but is thickened to the east.
GeoJSON
Fossils
Stromatolite such as Conophyton f.
Age
Depositional setting
Additional Information