Yijianfang Fm
Period:
Ordovician
Age Interval:
Darriwilian, (19)
Province:
Xinjiang
Type Locality and Naming
The type section is at Yijianfang to Tangwangcheng (40°N, 78°30'E) in Sanchakou, Bachu County, Xinjiang. The Yijianfang Fm was named by Zhou Zhiyi et al.in 1990.
Synonym:
Lithology and Thickness
The Formation is composed of calcirudite, calcarenite and limestone. The light gray massive limestone bearing Receptaculites represents a shallow biohermal facies. In the type area, the Yijianfang Fm is 54 m thick.
Lithology Pattern:
Reef limestone
Relationships and Distribution
Lower contact
The Formation rests conformably on the siliceous banded calcirudite at the top of the Yingshan Fm
Upper contact
It is conformably overlain by the thick-bedded sandy bio-calcarenite bearing glauconite at the base of the Tumxuk Fm.
GeoJSON
null
Age
Darriwilian.
Age Span:
Beginning stage:
Darriwilian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
469.42
Ending stage:
Sandbian
Fraction up in the ending stage:
0.0
Ending date (Ma):
458.18
Depositional setting
It represents a shallow biohermal facies.
Depositional pattern:
Additional Information
Compiler:
Jianpo Wang and Xiaofeng Wang