Yiwa Fm
Period:
Carboniferous
Age Interval:
C11 (43), early Early Carboniferous
Province:
Gansu, Sichuan
Type Locality and Naming
The type section is located at Yiwagou (hence also named the Yiwagou Fm), 18 km north of Diebu County, Gansu. It was named by Qin Feng and Gan Yiyan in 1973.
Lithology and Thickness
Limestone. Dark-gray limestone and clayey limestone, with chert nodule-bearing limestone at top; 167.5 m thick.
Lithology Pattern:
Clayey limestone
Relationships and Distribution
Lower contact
Conformable contact with the underlying Zharugou Fm
Upper contact
Conformable contact with the overlying Lueyang Fm
Regional extent
GeoJSON
null
Fossils
Corals Pseudouralinia sp. and Stelechophyllum sp.; Brachiopods Eochoristites sp., Plicochonetes sp., etc.,
Age
late Yanguanian = early Early Carboniferous
Age Span:
Beginning stage:
Tournaisian
Fraction up in beginning stage:
0.6
Beginning date (Ma):
351.76
Ending stage:
Tournaisian
Fraction up in the ending stage:
1.0
Ending date (Ma):
346.73
Depositional setting
It is interpreted as a platform neritic−deep lake facies
Depositional pattern:
Additional Information
Compiler:
Wang Rennong