Nianbo Fm
Period:
Paleogene
Age Interval:
Early to Middle Eocene, (9a)
Province:
Xizang (Tibet)
Type Locality and Naming
Named by the Tibet Regional Geological Survey Party in 1991. The naming section is located at the Xiagunba section of Nianbo Village 39 km southwest of Linzhou County, Tibet.
Lithology and Thickness
Purplish red and light yellow conglomerate and lithic sandstone with intermediate-acid tuff and andesite and locally fresh-water limestone. The formation is a suite of clastic rocks, intermediate-acid volcanic lava and pyroclastic rocks with a thickness of 716 m.
Lithology Pattern:
Conglomerate
Relationships and Distribution
Lower contact
It has an unconformable contact with the underlying Paleocene (?) Dianzhong Fm.
Upper contact
It has an unconformable contact with the overlying Eocene Pana Fm.
Regional extent
It is distributed in the area from Lhasa to Ngari.
GeoJSON
null
Fossils
It contains ostracods and gastropods (Amnicola sp.)
Age
The formation has K-Ar ages of 49.9, 50 and 39.5 Ma.
Age Span:
Beginning stage:
Ypresian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
56.00
Ending stage:
Lutetian
Fraction up in the ending stage:
0.75
Ending date (Ma):
42.79
Depositional setting
Depositional pattern:
Additional Information
Compiler:
Tao Deng, Yuanqing Wang, Qian Li, et al.