Niedong Fm
Type Locality and Naming
South Lhasa Block – LhasaCity. The Niedong Formation was erected by Wang Naiwen et al in 1983. The section for the designation is at Shihuiyao of Niedong of the Lhasa City, Xizang.
Lithology and Thickness
The Niedong Formation is represented by gray sandy and clayey flysch sediments. Lower part is built up by gray and gray green medium and thin-bedded feldspar quartz sandstone interbedded with siltstone, intercalated with small amounts of limestone (bearing ammonites and bivalve debris), and gray and grayish white feldspar quartz sandstone, siltstone and shale. Upper part is gray, grayish green and dark gray sandstone and siltstone interbedded with shale, and gray black and dark gray and gray green shale and siltstone with sandstone, bearing floras debris. The Niedong Formation is about 500 m thick.
Relationships and Distribution
Lower contact
Its base marked by gray medium and thin-bedded siltstone and shale occur unconformably on gray medium and thin-bedded slate at the top of the Budala Fm (J3-K1).
Upper contact
Conformable contact to the overlying Liuwau Fm where the Niedong Fm sandstone and shale becomes interbedded with moderately thick-bedded limestone.
Regional extent
The present formation occurs from Niedong to Jiare of the Lhasa City and on the southeast side of the Lhasa River. It is persistent in lithology and has been locally metamorphosed due to the intersection of granite veins. It contains plant debris, suggestive of marine regression. The Linbuzong Fm and the Chumulong Fm are typical marine regression facies, indicating that the southern and northern facies zones are different. In the Jiare town, the base of the formation is intruded by the granite bodies, and is likely to contact unconformably with the Budala Fm south of the Lhasa bridge.
GeoJSON
Fossils
None listed
Age
Depositional setting
Flysch
Additional Information