Gedasi Fm
Type Locality and Naming
The type section is located near Gedasi Village in northern Huilong Township, Zhen’an County, Shaanxi Province. It was named by Zhao Yazeng and Huang Jiqing in 1931.
Lithology and Thickness
Slate, siltstone (Flysch). It is composed of rhythmic interbeds of gray to dark-gray silty slate and sericite slate with thin-bedded siltstone, occasionally intercalated with calcareous sandstone, feldspathic quartz sandstone and sandy limestone. The sandstone possesses graded bedding and flute marks; the siltstone has laminated bedding. The rhythmite thickness is commonly 3 to 6 cm (ranges from 1 to 9 cm), and the rhythmites are equivalent to the CDE of Bouma sequence and (A) BCD (E) assemblage, indicating deep-water turbidite deposits. The outcropping thickness is more than 1776 m.
Relationships and Distribution
Lower contact
The Gedasi Fm outcropped along Qianyou River overlies conformably on the Gudaoling Fm of Frasnian.
Upper contact
The top of this Formation is absent.
Regional extent
The Gedasi Fm is mainly distributed in the area of Zhen’an and Zhashui, north of the Yunzhen--Kuanping (Zhashui) fracture zone.
GeoJSON
Fossils
Fossils haven’t been found so far in this formation.
Age
Depositional setting
Flysch. The rhythmite thickness is commonly 3 to 6 cm (ranges from 1 to 9 cm), and the rhythmites are equivalent to the CDE of Bouma sequence and (A) BCD (E) assemblage, indicating deep-water turbidite deposits.
Additional Information
The Gedasi Fm is a synchronous deposit in relation with the rhythmic clastics of the Jiuliping Fm located south to it.