Fuxian Fm
Type Locality and Naming
Ordos Basin. The type locality is situated in the vicinity of the Fuxian County Town, Sha’anxi Province; with its reference section being situated at the Dashenhao Gully 20 km to the northwest of the Fuxian County Town. It was named by Li Desheng as the “Fuxian Horizon”.
Synonym: （鄜县组）
Lithology and Thickness
It is composed mainly of purple silty mudstone, intercalated with yellow-green fine-grained sandstone and siltstone, with the increase of grey-green sandstone in its upper part, and with the occurrence of calcareous concretions in the mudstone. Its thickness is of 72 m.
Relationships and Distribution
Lower contact
Its basal part with a layer of grey-brown fine-grained sandstone intercalated with grey-green siltstone is in a disconformable contact with the underlying Wayaobao Fm (top of Yanchang Gr) of upper Triassic.
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Yan'an Fm.
Regional extent
Ordos Basin. The formation is distributed in the areas of Nanniwan, Yan’an, Shenmu and Fugu in northern Sha’anxi, as well as in the area of Zhungar Banner of Inner Mongolia. The lithology and thickness of the present formation tend to vary greatly from place to place. As in the area of Nanniwan it represents sandy conglomerate, with a thickness of 75 m; in the vicinity of Yan’an City it consists largely of grey-brown fine-grained sandstone and siltstone, with a thickness of several meters to over 10 m; in the area of Gushan Township and Wuziwan of Fugu County its lower part consists of grey-yellow gritstone, pebble-bearing sandstone, and purple and grey-violet sandy mudstone, while its upper part consists of green-yellow and dark-grey shales, oil shale and carbonaceous shale, with a thickness of several meters to over 100 m.
GeoJSON
Fossils
It yields Eosestheria fossils as represented by Eosolimnadiopsis gushanensis; bivalve fossils: Ferganococha subcentralis and etc; as well as spore-pollen and plant fossils.
Age
Depositional setting
Additional Information