Pingtou Fm
Type Locality and Naming
The type section is located between Wujiaba to Quanducun Village, 38 km south of Lixian County, Gansu. It was named by Geological Team of West Qinling, and Qin Feng, Gan Yiyan formally quoted it as a lithological member in lower part of Yushuping Fm.
Lithology and Thickness
Clastic rock. This formation, 2494 m thick in total, is composed of fine-grained clastic rock intercalated with carbonate rock. It is divided into five successive units:
Lowermost unit of dark-gray thin to medium-bedded limestone intercalated with calcareous slate and sandstone, 494 m thick;
Second unit of greenish-gray sandy slate intercalated with thin-bedded sandstone and calcareous sandstone, 810 m thick;
Third unit of dark-gray thin- to medium-bedded limestone intercalated with thick-bedded limestone, 220 m thick;
Fourth unit of dark-gray sandy slate intercalated with calcareous quartz sandstone, 865 m thick;
Uppermost Fifth unit of dark-gray thin-bedded limestone intercalated with calcareous slate, 105 m thick.
Relationships and Distribution
Lower contact
It conformably overlies the Yuchiba Fm.
Upper contact
It conformably overlies the Longlinqiao Fm.
Regional extent
This formation is distributed in Dangchang in west of Xihanshui, Lixian County areas; the carbonate component increases eastward; and to west of Dongshan area, the facies changes into the carbonate platform facies of lower part of Honglingshan Fm. In Wujiashan of Chengxian County, east of Dongshan, the facies returns to clastic rock intercalated with carbonate rock which is called the Guangjinba Fm.
GeoJSON
Fossils
The limestone intervals yield abundant brachiopods Stringocephalus and coral Pseudomicroplasma uralica, Argutastrea quadrigemina etc.
Age
Depositional setting
Additional Information