Beimenxia Fm
Type Locality and Naming
Eastern Qinghai-SE Gansu border region. The Beimenxia Fm was named by Team of Regional Geological Survey, Qinghai Province. Comprehensive Party of Geology, Northwest Bureau of Geology, Ministry of Geology in 1964. The type locality for the formation establishment is Beimenxia, Huangzhong County, Qinghai Province. It is the uppermost formation in Huashishan Gr.
Synonym: (北門峡组)
Lithology and Thickness
The Beimenxia Fm is dominated by dolomitic carbonate rock. Lower part consists of slate, silty-argillite, sandwiched with dolomitic sandy conglomerate, dolomite, limestone and volcanic rock. Upper part is a carbonate platform deposit composed of thick-bedded, massive-bedded dolomite, siliceous dolomite and thick-bedded, mega-thick-bedded, siliceous banded dolomite. The top is intercalated with chert. It is laterally stable both in lithology and in thickness. The formation, 860 m thick
Relationships and Distribution
Lower contact
It is in conformable contact with the underlying Kesur Fm.
Upper contact
It is in unconformable contact with Bayinhe Gr (Lemengou Fm)
Regional extent
Eastern Qinghai-SE Gansu border region. The Beimenxis Fm is widely distributed at Malaode Mountain, Gangcha County; Beimenxia, Huangzhong County; Laoye Mountain, Datong County; and Nanmenxia, Huzhu County, of Qinghai Province.
GeoJSON
Fossils
The formation contains microplants in Malaode Mountain, such as Asperatopsopho- sphaera sp., A. cf. partialis, Leiopsophosphaera sp., Trachysphaeridium sp., Trematosphaeridium sp.; stromatolites, Tungussia f., Conophyton cf. lituum, Anabaria f., Minjaria f., Colonnella f..
Age
Depositional setting
Additional Information