Qubeiya Fm
Type Locality and Naming
South Lhasa Block - Xigaze forearc Basin. The Qubeiya Formation was erected by the Xizang Regional Geological Survey Team of the Xizang Bureau of Geology and Mineral Resources in 1983. The section for the designation is in Qubeiyagou of the Qiongguo Town about 30 km north of the Zhongba County, Xizang.
Lithology and Thickness
Lower part of the Qubeiya Formation is built up by gray massive conglomerate with medium and coarse-grained sandstone and siltstone, forming rhythms. Middle part grayish green, grayish white and purple red sandstone and mudstone, with bioclastic rocks at the top, bearing belemnite and bivalve debris. Upper part gray silty mudstone with thin-bedded bioclastic limestone and calcareous, siliceous and clayey sandstone. The Qubeiya Formation is in excess of 930 m in thickness.
Relationships and Distribution
Lower contact
The base marked by gray sandy shale lies conformably on the underlying Padana Fm.
Upper contact
The top of the formation marked by gray and purple red silty shale lies conformably under the Paleogene Cuojiangding Gr marked by variegated sandy conglomerate.
Regional extent
The present formation occurs in Cuojiangding of the Zhongba County, Rujiao of the Saga County. It is persistent in lithology and ranges from 930 to 1113 m in thickness.
GeoJSON
Fossils
In Qiongguo, it yields ammonites Sphenodiscus cf. solgerites sp., Libycoceras zhongbaensis, L. tibeticus, Pochydiscus cf. hidakaensis, Manambolites cucjiangdingensis, M. pivaeteaui, etc.; bivalves Pholadomia (P.) spp., P. (P.) radiatula, P. (P.) cf. scaphoides, Amphiodonte ostracina, Inoceramya ?xizangensis, Sulcoperculina sp., Pseudorbitoides yini, Omphalocyclus sp., etc.
Age
Depositional setting
The thriving biotas indicate a normal neritic sedimentary environment.
Additional Information