Piyuancun Fm
Type Locality and Naming
The type section of Piyuancun Formation is the Lantian section, lying about 1.5 km north of Lantian Town, Xiuning County, southeastern Anhui Province (118°05’E, 29°55’N). It was remeasured by Yan Yongkui et al. from Nanjing Institute of Geology and Mineral Resources in 1992. The Piyuancun Formation was named by Qian et al. (1964). The name is derived from Piyuancun Village in Lantian Township, Xiuning County, Huangshan City, southern Anhui Province. This formation spans the Ediacaran-Cambrian boundary.
Synonym: （皮园村组）; Pihyuuan sandstone, but this may underlie it. (see Additional Information
Lithology and Thickness
The Piyuancun Formation is a sequence of siliceous rocks. Lower part consists largely of black, thick-bedded striped siliceous rock with alternation of black and light grey bands. Upper part consists of light grey, thin- to moderately medium-bedded siliceous rock and siliceous shale. The rocks contain rich organic matter and bear fine horizontal bedding usually and waving bedding occasionally. In the section, the formation is 186.98 m thick. The formation is stable in lithology, but the thickness varies largely from 37 to 197 m.
Relationships and Distribution
Lower contact
The Piyuancun Fm rests conformably on the underlying Lantien Fm of Ediacaran System.
Upper contact
It is overlain either disconformably by Hetang Fm or conformably by Wangyinpu Fm.
Regional extent
The Piyuancun Formation is exposed in the Jiangnan Slope and Jiangbei Slope areas of South China Region, distributed in southern and eastern Anhui Province, including Jingxian, Ninguo, Qingyang, Shitai, Shexian, Yixian, Xiuning, Quanjiao and Chaohu counties; northwestern Jiangxi Province, including Xiushui, Wuning, Ruichang and Pengze counties.
GeoJSON
Fossils
The Piyuancun Formation yields commonly sponge spicules. It yields also micropalaeoplant fossils Trachysphaeridium, Lophosphaeridium, Piyuancunella and Leiopsophosphaera.
Age
Depositional setting
Additional Information
Lithology and Thickness:
The Piyuancun Formation is a sequence of siliceous rocks. Lower part consists largely of black, thick-bedded striped siliceous rock with alternation of black and light grey bands. Upper part consists of light grey, thin- to moderately medium-bedded siliceous rock and siliceous shale. The rocks contain rich organic matter and bear fine horizontal bedding usually and waving bedding occasionally. In the section, the formation is 186.98 m thick. The formation is stable in lithology, but the thickness varies largely from 37 to 197 m.
Lithology-pattern: Chert
Relationships and Distribution:
Lower contact:
The Piyuancun Fm rests conformably on the underlying Lantien Fm of Ediacaran System.
Upper contact:
It is overlain either disconformably by Hetang Fm or conformably by Wangyinpu Fm.
Regional extent:
The Piyuancun Formation is exposed in the Jiangnan Slope and Jiangbei Slope areas of South China Region, distributed in southern and eastern Anhui Province, including Jingxian, Ninguo, Qingyang, Shitai, Shexian, Yixian, Xiuning, Quanjiao and Chaohu counties; northwestern Jiangxi Province, including Xiushui, Wuning, Ruichang and Pengze counties.
GeoJSON:
Fossils:
The Piyuancun Formation yields commonly sponge spicules. It yields also micropalaeoplant fossils Trachysphaeridium, Lophosphaeridium, Piyuancunella and Leiopsophosphaera.
Age:
Ediacaran through Jinningian probably
Age span:
Beginning stage: Ediacaran
Fraction up in beginning stage: 0.5
Beginning date (Ma):
Ending stage: Fortunian
Fraction up in ending stage: 0.7
Ending date (Ma):
Depositional setting:
Depositional-pattern:
Additional Information
The informal lithostratigraphic unit Pihyuan sandstone, proposed by Li and Li (1930), was named also after the Piyuancun Village. This name was appeared in a stratigraphic column with very brief description on lithology. According to Li (1939, p. 465), the Pihyuan sandstone is overlain by the questioned Lantien Tillite (Lantien Fm) in southern Anhui Province. The Pihyuan sandstone was regarded to be a senior synonym of the Piyuancun Fm by Li and Jiang (1997) and Zhang (2009), but as it is different in name, the Pihyuan rather than Piyuancun, in lithology, sandstone rather than siliceous rock, and in an older stratigraphic position, underlying rather than overlying the Lantien Formation, it should not be equivalent to the Piyuancun Formation but is probably to the “Nantuo sandstone” (Liantuo Formation), which underlies the Nantuo Tillite (Nantuo Formation).