Tangchi Fm
Type Locality and Naming
The type section is at Village Fengming in Tangchi, Yiliang, Yunnan. Tangchi Fm is derived from the Tangchi Series proposed by Wang Yuelun and Bian Zhaoxiang in 1936. The Tangchi Gr had previously been referred to the Ordovician in Tangchi, Yiliang. In 1940, Bian Zhaoxiang renamed it the Tangchi Shale. In 1959, Lu Yanhao suggested that Guo Wenkui's (1941) Hongshiya Fm includes the Tremadocian and Arenig strata, in which the former is the Bian's Tangchi Shale. In 1962, Zhang Wentang renamed the Bian's Tangchi Shale the Tangchi Shale Fm, which was subsequently in turn renamed the Tangchi Fm widely accepted.
Synonym: (汤池组）
Reference Section:
The reference section is at Hongshiya in Ercun of Kunming City.
Lithology and Thickness
The formation is composed of a Lower part of medium- to coarse-grained quartz sandstone intercalated with shale, and an Upper part of shale intercalated with sandstone. In the type area, the Tangchi Fm is 50 m thick. This stratigraphic unit is exposed in eastern Yunnan (45-100 m thick) and southwestern Sichuan (130-200 m thick).
Relationships and Distribution
Lower contact
It rests disconformably on the argillaceous limestone or dolomite of the Cambrian.
Upper contact
In most below-mentioned areas, the Tangchi Fm is conformably overlain by the Hongshiyan Fm (Hongshiya Fm), but in Tangchi, Yiliang it is disconformably overlain by the Devonian.
Regional extent
This stratigraphic unit is exposed in eastern Yunnan and southwestern Sichuan. In 1958, Sheng Xinfu considered the Tangchi Shale in northeastern Yunnan to be equivalent to the upper part of the Tongzi Fm in northern Guizhou.
GeoJSON
Fossils
The upper part yields trilobites of Tungtzuella assemblage.
Age
Depositional setting
Additional Information