Xiaxi Fm
Type Locality and Naming
It was named by Wang Naiwen, Liu Guifang, Chen Guoming in 1983. The naming section is located in the area east of the Zhangda Village till the Zhela Mts, Zhangda Region, Langkazi County, Tibet, with its reference section being situated to the north of the Xiaxi Village, Zhangda Region, Langkazi County, Tibet. Middle formation in Zhela Gr.
Synonym: （夏西组）
Lithology and Thickness
Lower part is composed of grey and grey-green siliceous shales and calcareous shale, intercalated with many layers of grey limestones, siliceous limestones and siltstone lenses, containing ferruginous and siliceous concretions. Upper part is composed of grey medium-, and thin-bedded limestones and marls, intercalated with shale. Its thickness is of 150 m.
Relationships and Distribution
Lower contact
Its basal part consisting of grey and grey-green siliceous and calcareous shales is in a conformable contact with the underlying Binhu Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Bajiutang Fm
Regional extent
The formation is distributed essentially in the Zhela and Xiaxi areas on the eastern side of the Yangzhuoyong Co, on the southern slope of the Shelangre Mts till the Bajiutang area in the Longbu snow patch, with a consistent lithology, and with a thickness of 90-150 m. In the area of the Longbu snow patch there are no Compiler
Jingeng Sha (coordinator) exposures of the formation, and with no base of it having been found, while in other regions the formation is found to be in a conformable contact with the underlying Binhu Fm.
GeoJSON
Fossils
It yields Belemnites fossils in the shale as represented by Belemnopsis sp.
Age
Depositional setting
Additional Information
Beginning date (Ma):
Ending stage: Bathonian
Fraction up in ending stage: 1.0
Ending date (Ma):
Depositional setting:
Depositional-pattern:
Additional Information
Compiler
Jingeng Sha (coordinator)