Gongcha Gr
Type Locality and Naming
Middle Qilian (north-central Gansu-Qinghai border region). The Gongcha Gr was named by Qian Jiaqi and Ye Yongzheng in 1981. The typical section is situated in Dagongcha to Yaodonggou, in Subei Mongolian Autonomous County, Gansu Province.
Synonym: （龚岔群）
Lithology and Thickness
The Gongcha Gr is a suite of fine clastic and carbonate formations bearing abundant stromatolites and microplants, which mainly formed two cycles of clastic rock to carbonate rock. Upward succession of the Qitadaban Fm, Wugesha Fm, Hashihar Fm and Yaodongou Fm. The carbonate rock in the west contains 1 to 3 layers of gypsum, with oolitic limestone, brecciform limestone and dolomite. Total thickness varies from 3022 to 4200 m.
Relationships and Distribution
Lower contact
It rests disconformably on the underlying Hua'erdi Fm (Tulai Movement).
Upper contact
The upper part disconformably underlies the Shibandun Fm of the Duoruonuor Gr. in middle Qilian and unconformably underlies the overlying Sinian Baiyanggou Fm (in north Qilian).
Regional extent
Middle Qilian (north-central Gansu-Qinghai border region). It is distributed in Dagongcha, Chaganburgas and Qitadaban in Subei County, Gansu Province, eastward to Wugeshan area in Qilian County, Qinghai Province. Northward, it also occurs in Jingtie Mt., Daliugou and Gulangxia etc.
GeoJSON
Fossils
Except for the Qitadaban Formation, the Gongcha Group yields abundant stromatolites, dominated by Gymnosolen, Katavia, Jurusania and Linella. Microplants includes Trachysphearidium sp., Asperatopsophosphaera sp., Quadrat imorpha sp., Tasmanitaes sp., Zonosphaeridium sp. etc.
Age
Depositional setting
Additional Information