Gucobingzhan Fm
Type Locality and Naming
The type section is located to the west of the Guco Village in the vicinity of the No. 4 Maintenance Squad of the Dingre-Nyalam Highway, Tibet. It was named by Liu Guifang and Wang Si’en, the authors of the present stratigraphic lexicon. Lowest formation in the Gucuocun Gr
Synonym: （古错兵站组）, Gucuobingzhan Fm
Lithology and Thickness
It is composed of grey, grey-black, and yellow-green sandstones and shales, rich in concretions. Its basal part is grey massive quartz-sandstone (quartzite); its Lower and Middle parts are grey-black, grey and grey-green shales, rich in calcareous concretions; and the Upper part is alternating layers of black shale together with yellow-green thin-bedded and medium-grained sandstone, with shale containing concretions. Its thickness is of 265 m.
Relationships and Distribution
Lower contact
The basal part of the formation is in a conformable contact with the underlying Menkadun Fm
Upper contact
The top part of it is in a conformable contact with the overlying Manquhe Fm (K1).
Regional extent
The formation is distributed mainly in the area of Menbu to Guco, Nyalam County, with a consistent lithology.
GeoJSON
Fossils
In the area of Guco the middle and lower parts of the formation yield abundant ammonites’ group of the Berriasella jacobi zone.
Age
Depositional setting
It belongs to tidal-flat deposits.
Additional Information