Dachaigou Fm
Type Locality and Naming
The type section is located in the Sijiaoyang trench of Germu City, Qinghai Province. It was named by the Regional Comprehensive Geological Reconnaissance Party of Qinghai Province in 1985.
Lithology and Thickness
Limestone: Grey and dark-grey medium- and thick-bedded limestones, intercalated with dolomite, and of grey-black limestone, intercalated with shale. Thickness is over 176 m.
Relationships and Distribution
Lower contact
Conformable contact with the underlying limestone of Sijiaoyanggou Fm or the Nuomuhonghe Fm (both coeval latest-Carboniferous to earliest Permian).
Upper contact
Major hiatus. Regionally, the next younger unit is the Xiahuancang Fm of Early Triassic.
Regional extent
Distributed on the southern margion of the Chaidamu Basin in a nearly E-W-trend, with its scatter exposures being found in the Kongbulake area on the northern slope of the Qimantag Mt., South Hills of Yemaquan, as well as in the Sijiaoyang trench, with a thickness of about 40-176 m.
GeoJSON
Fossils
Fusulinida represented by the Eoparafusulina-Pseudofusulina zone;
Corals represented by the Kepingophyllum-Anfractophyllum intortum assemblage, and the Michelinia pecteniformis of Tabulata;
Brachiopods represented by Kulunia aspera-Dictyoclostus cf. uralicus assemblage;
Bryozoan represented by Fenestella hangchouensis, Fistuliramus hunanensis and Polypora cf. koninckiana.
Age
Depositional setting
It is interpreted as a shallow-sea facies deposit.
Additional Information