Denytangga Fm
Type Locality and Naming
It was proposed by the Xizang Zizhiqu Party of Comprehensive Reconnaissance Survey in 1980. The type section is located at the ridge, west of the road about 12 km north of Yunzhug Township in Xianza County, Xizang Zizhiqu.
Synonym: （德乌卡下组）
Lithology and Thickness
Lower part, 40 m thick, consists of interbeds of black graptolite shale with black bioclastic limestone. Upper part, approximately 50 m in thickness, is composed of yellow mudstone intercalated with purplish brown calcareous shale.
Relationships and Distribution
Lower contact
The formation conformably contacts onto the underlying Riajiaoobuduo Fm of the Upper Ordovician (not in Ordov lexicon entries); regionally, the next older unit is the Xialazi Fm of upper Ordovician.
Upper contact
The formation conformably contacts with the overlying Zhanongema Fm
Regional extent
It is extremely restricted in distribution, as its exposures observed merely at the type section locality.
GeoJSON
Fossils
The lower part of the formation is rich in graptolite of Normalograptus persculptus zone and the Parakidograptus acuminatus zone. The upper part, yields abundant graptolite of the Orthograptus vesiculosus zone, Pristiograptus cyphus zone, P. gregarius zone, Oktavites communis zone and Spirograptus turriculatus zone; and conodont of the Pterospathodus celloni zone.
Age
Depositional setting
Additional Information