Ganquan Gr
Type Locality and Naming
The type section is located at Ganquan, 73 km northwest of Dunhuang, Gansu. It was named by the No. 2 Gansu Party of Regional Geological Survey in 1973.
Lithology and Thickness
Siltstone, Limestone and Volcanics. Composed of very thick littoral facies deposits, dominated by marine clastic rock and intermediate-acid volcanic rock. In the type section, the Lower part has a 10-m thick conglomerate at bottom, followed by gray and gray-green siltstone, calcareous-clayey feldspar-quartzose sandstone and oolitic limestone. The Upper part comprises gray-green and gray-black rhyolite, acid tuffaceous lava and rhyolitic volcanic tuff breccia, intercalated with dacite, siltstone and limestone lenses. Thickness >1613 m.
Relationships and Distribution
Lower contact
Uncertain. Regionally, the next younger unit is the Jijitaizi Fm limestone
Upper contact
Unconformable contact with the overlying Shuangputang Fm
Regional extent
Outcrops in the Ganquan area in the south zone of Beishan Mt., and confined to Pocheng Mt. and Nanpoziquan of Subei County for the north zone
GeoJSON
Fossils
The limestone in the Lower part at type section contains Corals Tachylasma? sp. and Syringopora sp., and the Upper part contains plant Paracalamites ? sp. At the place 4 km north of the section, this group yields Brachiopods Choristites pavlovi, C. nikitini, Marginifera orientalis, etc.; Corals Paracarruthersella sp., Amplexocarinia sp., etc.; Ammonoids Glaphyrites sp., Agathiceras sp., Eoasianites sp., etc.
Age
Depositional setting
It is interpreted as a
Additional Information