Xiadongshan Fm
Type Locality and Naming
Hualong basin (Xining). The naming section is located in the vicinity of Xiadongshan in the Hualong basin, Qinghai. Named by the Fifth Team of the Comprehensive Geological Party, Qinghai Bureau of Geology in 1989.
Lithology and Thickness
Mainly mudstone, siltstone, sandstone and some fine conglomerate with different tints of brick-red, earth-red, gray and brown. The formation consists dominantly of fine-grained deposits, occasionally intercalated with limestone. Horizontal bedding is well developed and locally oblique bedding and cross bedding are also observed. The thickness of the formation varies greatly: it is 304 m thick in the vicinity of Xiaodongshan in the Hualong basin and 507 m thick in the vicinity of He’erjia and Amigang in the Guide basin.
Relationships and Distribution
Lower contact
The formation has a conformable contact with the underlying Miocene Charang Fm.
Upper contact
The formation has a conformable contact with the overlying Shangtan Fm.
Regional extent
This basin is widespread at Ashigong, Hongliutan, Reshuitan, He’erjia and Duoleicang of the Guide basin and Yashiga, Xiadongshan and Qunke of the Hualong basin.
GeoJSON
Fossils
Rodentia: Sinocastor sp.; Proboscidea Gomphotheriidae indet., Perissodactyla: Hipparion platyodus, Chilotherium sp.; Artiodactyla: Axis sp., Palaeotragus cf. decipiens, Gazella gaudryi; The sporopollen assemblage is Chenopodipolllis-Ulmipollenites-Abeitineaepollenites, consisting chiefly of Chenopodiaceae, Artemisia, Ulmus, Pinus and Quercus.
Age
Depositional setting
Fluvio-lacustrine deposits.
Additional Information