Ayishan Fm
Period:
Ordovician
Age Interval:
Tremadocian-Dapingian, (23)
Province:
Qinghai
Type Locality and Naming
The type section is at the Donggou village of Huangzhong County, Qinghai. The Ayishan Formation was named by No. 2 Qinghai Party of Regional Geological Survey in 1976.
Synonym: (阿夷山组)
Lithology and Thickness
Lower part of the Ayishan Fm is intermediate-basic tuff, quartz keratoporphyry with volcanic detritus glutenite. The Middle and Upper parts are mainly andesite intercalated with basalt. In the type section, the formation records an incomplete thickness of 1776.3 m.
Lithology Pattern:
Lava
Relationships and Distribution
Lower contact
The formation rests conformably on the Cambrian Huabaoshan Fm
Upper contact
It is covered by the Chapu Gr
Regional extent
GeoJSON
null
Fossils
Age
Age Span:
Beginning stage:
Tremadocian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
486.85
Ending stage:
Dapingian
Fraction up in the ending stage:
0.0
Ending date (Ma):
471.26
Depositional setting
Depositional pattern:
Additional Information
Compiler:
Jianpo Wang and Xiaofeng Wang