Tianzhu Fm
Type Locality and Naming
The type section is at Sijiagou in Xiehao, Wuwei, Gansu. The Tianzhu Fm was named by Mu Enzhi and Zhang Youkui in 1964.
Synonym: (天祝组)
Lithology and Thickness
The formation is composed of shale intercalated with sandstone. In the type area, the Tianzhu Fm is 229 m thick.
Relationships and Distribution
Lower contact
At Daogou, the Tianzhu Fm is composed of purple conglomerate, and rests unconformably on the Chelungou Fm, with a covered lower boundary.
Upper contact
It is conformably overlain by the shale at the base of the Sijiagou Fm
Regional extent
The Tianzhu Fm, with a persistent lithology, is 60-318 m thick, and is exposed at Qiqiaogou (60 m thick) near Xiehao, Sijiagou (229 m thick), Zhigou (121 m thick), Daogou (110 m thick), Dajing (177.5 m thick) and Ningchanghe in Tianzhu (318 m thick), Gansu.
GeoJSON
Fossils
This stratigraphic unit yields graptolites of Amplexograptus gansuensis assemblage, and is equivalent to Climacograptus (Diplocanthograptus) peltifer zone to C. wilsoni zone.
Age
Depositional setting
Additional Information