Tuanbugou Fm
Type Locality and Naming
The type section is located at Tangbugou, 18 km northwest of Wenxian County, Gansu. It was named by Zhang Yan in 1961, and Cao Xuanduo formally quoted it in 1990.
Lithology and Thickness
Slate, limestone. This formation is separated from the underlying Shawan Fm by the appearance of shale and calcareous shale intercalated with thin-bedded limestone at a conformable contact. Above that, it is characterized by dark-gray to blackish-gray medium- to thick-bedded micrite limestone, dolomitic-bearing micrite with siliceous nodules, and banded micrite intercalated with thin-bedded limestone and calcareous slate. Its uppermost portion is characterized by thick-bedded to massive limestone with siliceous nodules and banded micrite. The total thickness is 196.4 m.
Relationships and Distribution
Lower contact
This formation is separated from the underlying Shawan Fm by the appearance of shale and calcareous shale intercalated with thin-bedded limestone at a conformable contact.
Upper contact
The top boundary to the Cakuohe Fm is the top of a thick-bedded limestone with flint nodules (Cao Xuanduo et al., 1990).
Regional extent
GeoJSON
Fossils
The main fossils are coral Temnophyllum, Hexagonaria, Alveolitella, Natalophyllum, Syringopora, and brachiopods Emanuella, Schizophoria, etc.
Age
Depositional setting
It is interpreted as a carbonate platform facies, because within the limestone are small bedded to hummocky stromatopora reefs.
Additional Information