Dadianzi Fm
Type Locality and Naming
N. Hebei. It was named by Wang Si’en in 1990. The naming locality is only situated at Dadianzi, Luanping County, Hebei Province, with the naming section being located at Jingshang-Donggou of Dadianzi, Luaping, Hebei Province; and with its reference section being located 2 km northeast of the naming section.
Wang Sien (1990) divided the Dabeigou Formation into the Dabeigou Formation (narrow) and “Dadianzi Formation” in the Luanping Basin. The strata of the Dabeigou and Dadianzi formations are continuous exposed and of uniform lithology, the present lexicon remains the nomination of Dabeigou Formation for the general sequence, and the so called “Dadianzi Formation”is still the upper part of the Dabeigou Formation.
Synonym: “Dadianzi Formation”
Lithology and Thickness
The “Dadianzi Formation” is only the upper part of the Dabeigou Fm. Wang Si’en (1990) described that it composed of yellow-green and grey-green mudstone and sandstone, intercalated with conglomerate, and being divided into the lower and upper parts: Lower part, composed of purple-grey and yellow-green mudstone, silty mudstone, intercalated with grey-green and grey-white sandstone, with a thickness of 134.7 m. The total thickness of the particular formation is of 236.9 m.
[Figure: Lower part of “Dadianzi Formation” in Zhangjiagou section of Luanping County, Hebei Province]
[Figure: Upper part of “Dadianzi Formation” in Zhangjiagou section of Luanping County, Hebei Province]
[Figure: Mesured section of Dabeigou-Dadianzi formations in Zhangjiagou of Luanping County, Hebei Province]
Relationships and Distribution
Lower contact
The basal part serving as a layer of sandy conglomerate (the Fengwoliang Conglomerate) and being in a conformable contact with the underlying Dabeigou Fm.
Upper contact
Shown by D.P. Xi, X.Q. Wan et al. (2019; Cretaceous chapter of China Integrated Stratigraphy and Timescale) as underlying the Xiguayuan Fm.
Regional extent
It is distributed essentially in the Luanping Basin, with its distribution in a small amount as well as in the Fengning area, but with the rocks there becoming coarser, and with the thickness getting smaller.
GeoJSON
Fossils
It yields Eosestheria: Eosestheria cf. lingyuanensis, Yanshania dabeigouensis, Y. subovata; fish fossils of Lycoptera davidi; bivalves: Ferganoconcha curta, F. subcentralis, F. spp.; Ostracoda as represented by the Cypridea-Djungarica-Timiriasevia assemblage; bivalves: Ferganoconcha curta, F. spp.; Gastropoda: Probaicalia, vitimensis and Vertebrate: Luanpingosaurus jingshangensis.
Age
Depositional setting
Additional Information