Anniangniangqiao Fm
Type Locality and Naming
The type section is at area about 10 km west of Xinglong County (125°49′E, 51°48′N), re-measured by the No.1 Heilongjiang Party of Regional Geological Survey in 1980. The Anniangniangqiao Formation was named by Ma Jiajun in 1973, and was published by the Heilongjiang Compiling Group for Regional Stratigraphic Scale (1979). The name is derived from Anniangniangqiao, western Xinglong Village in Huma County, Heilongjiang Province.
Synonym: (安娘娘桥组)
Lithology and Thickness
The Anniangniangqiao Fm is divided into two lithologic parts. The lower part (conglomerate member) is unfossiliferous, and is characterized by gray, gray green conglomerate, pebbly tuff, feldspathic sandstone intercalated with conglomerate, fine-grained quartz sandstone and quartz siltstone. The clasts have a low maturity, and were deposited autochthonously or para-autochthonously. The upper part (slate member) is represented by yellowish green sericite-chlorite slate, silty sericite-chlorite slate. The formation shows a normal upward grading with the composition changing from complicated to simple. In the type section the formation records an incomplete thickness of 324.2 m.
Relationships and Distribution
Lower contact
The contact between the formation and the underlying strata is unknown due to diorite intrusion.
Upper contact
The contact between the formation and the overlying strata is unknown due to diorite intrusion. Regionally, the next younger unit is the Kunasenhe Fm
Regional extent
It is exposed west of Shiwuzhan, south of Xinglong Village and near Anniangniangqiao.
GeoJSON
Fossils
The upper part of the formation yields abundant Lingulid and rare ostracoda. Brachiopods of the Lingulella assemblage and ostracoda Arcuaria sp. have been observed near Anniangniangqiao.
Age
Depositional setting
Additional Information