Zhongpu Gr
Type Locality and Naming
The type section is at Shihuigou in Zhongbao, Yongdeng County, Gansu. The Zhongpu Gr was named by Gansu Party of Regional Geological Survey (1963), and was published by Gansu Compiling Group for Regional Stratigraphic Scale (1980).
Synonym: (中堡群）
Lithology and Thickness
The group is composed of a Lower part of intermediate basic lava and tuff characterized by pebbles and agglomerates, lower-middle part of limestone, tuff, slate and chert, and an upper part of alkali eruptive rocks. In the type area, the Zhongpu Gr recorded an incomplete thickness of 2235 m.
Relationships and Distribution
Lower contact
With a covered lower boundary. Along the Suyou River, it is 73.2 m thick, and is cut by fault in the upper and lower boundaries.
Upper contact
It is disconformably overlain by the Silurian. At Kebogou in southern Gansu, with a thickness of 3891 m, the Zhongpu Gr is cut by fault, and is unconformably overlain by the Silurian. Along the Suyou River, it is 73.2 m thick, and is cut by fault in the upper and lower boundaries.
Regional extent
The Zhongpu Gr has a persistent lithology and different exposure extents along the length of its outcrop. At Anmen in Yumen City, Gansu, it is 918 m thick, and only its upper part is exposed. In Jingyuan, it is over 3305 m thick, and is composed dominantly of clastic rock intercalated with minor volcanic rock and limestone lenses. In Qinghai, the Zhongpu Gr, with a maximum thickness of 4317 m, is exposed on the southern slope of eastern segment of Lenglong Hill and in Miban Hill in the eastern segment of Daban Mountain, and is dominated by sandy slate intercalated with chert and minor conglomerate (Qinghai Bureau of Geology and Mineral Resources, 1991).
GeoJSON
Fossils
The middle-upper part yields graptolites Husterograptus teretiusculus and Nemagraptus gracilis.
Age
Depositional setting
Additional Information