Sijiaoyanggou Fm
Type Locality and Naming
The type section is located at Sijiaoyanggou southeast of Yemaquan, Golmud City, Qinghai, and the reference section is at Dachaigou. It was named by the No. 1 Geological Party of Qinghai in 1975.
Lithology and Thickness
Limestone. Dominated by light-gray thick-bedded bioclastic limestone, intercalated with thin-bedded oolitic limestone and moderately thick-bedded dolomite, with purple oolitic clayey silt at bottom, 579.90 m thick. In the Diaosu and Haerzha areas, it is dominated by limestone, with chert nodules and bands, 152−244 m thick, mainly containing Fusulinids, with Zellia sp., Pseudoschwagerina sp., etc. in the upper and Triticites sp. in the lower part.
Relationships and Distribution
Lower contact
Conformable contact with the underlying Carboniferous Diaosu Fm
Upper contact
Conformable contact with the overlying Lower Permian Dachagou Fm
Regional extent
GeoJSON
Fossils
The fossils are dominated by Fusulinids, including Quasifusulina longissima, Sphaeroschwagerina sphaerica, Eoparafusulina dulanensis, etc. in the Upper part; while the Lower part contains mainly Triticites variabilis, Pseudofusulina sp., Rugosofusulina sp., etc. as well as Corals Caninia sp., Amygdalophylloides sp., etc.; Brachiopods Choristites nikitini, Dictyoclostus taiyuanfuensis, Martinia sp., etc.
Age
Depositional setting
It is interpreted as dominated by shallow-marine carbonates
Additional Information