Dongsheng Fm
Type Locality and Naming
Ordos Basin. The No.206 Geological Team of the Bureau of Petroleum under the Ministry of Geology and Mineral Resource erected the Dongsheng bed in 1956. The reference section is in Hashilachuan of Dalad Qi, Inner Mongolia (110°3′50″E; 39°58′50″N).
In 1978 the First Regional Geological Survey Team of the Inner Mongolia renamed the Dongsheng bed as the Dongsheng Formation. In 1994 the Inner Mongolia Stratigraphic Sorting Group assigned the formation to the Zhidan Gr (for detail, refer to the Zhidan Gr). Uppermost formation in Zhidan Gr.
Synonym: Lamawan Fm
Lithology and Thickness
Lower part of the Dongsheng Formation is mainly represented by yellow green conglomerate. Upper part is gray green sandstone interbedded with loose red sandy mudstone. The formation is 269 m thick.
Relationships and Distribution
Lower contact
The basal part, comprising gray green, gray white and yellow green conglomerate, lies unconformably on the underlying Middle Triassic Ermaying Fm. It may rest unconformably on the Cambrian-Jurassic. In the Lamawan area of the Qingshuihe County, the Lamawan Fm, 226 m thick, was used which lies conformably on the underlying Jingchuan Fm.
Upper contact
The top part, comprising loess-like red siltstone and sandy mudstone, lies unconformably under the overlying Pliocene.
Regional extent
The present formation is present in Gaotouyao, Dongsheng and Jungar Qi of the Inner Mongolia and extends from east to west for about 150 km in the elongated shape. In the Lamawan area there is a breccia bed dominated by gray breccia at the base of the formation, and coal streaks are intercalated in the upper part. In the Baoersitaigou area the formation is intercalated with basalt and is up to 560 m in thickness.
GeoJSON
Fossils
The formation yields floras Phoenicopsis acutifolia, Coniopteris onychioides, Stenorachis bulunensis in the Lamawan area of the Qingshui River, and Reptilia Psittacosaurus youngi in Maobulanggou, as well as fish and sporopollen.
Age
Depositional setting
It is mainly of lacustrine facies.
Additional Information