Dadongchang Fm
(44), Kungurian Stage (uppermost Cisuralian Epoch) through Guadalupian Epoch [latest-Early through Middle Permian]
Type Locality and Naming
The type section is located at Dadongchang, Tengchong County, Yunnan Province (98°34′, 25°31′). It was named by the Yunnan Regional Geological Reconnaissance Party in 1985.
Lithology and Thickness
Limestone: Light-grey to dark-grey medium-, and thick-bedded massive limestones, containing chert nodules and siliceous bands, with its upper part being intercalated with dolomitic limestone. Basal part has the occurrence of light-yellowish pink bio-crystalline limestone.
Relationships and Distribution
Lower contact
Disconformable contact with the underlying Kongshuhe Fm.
Upper contact
Conformable contact with the overlying Daba Fm.
Regional extent
Distributed in the Dadongchang, Wujiazhai, Kongshuhe areas of Tengchong County in a S-N-trend, with a thickness of 196.6-276.6 m. In the Dadongchang area of the northern part of province the limestone contains chert nodules and siliceous bands, intercalated with dolomitic limestone, with no top being found and with an exposed thickness of 214 m; southerly in the Xianren Mt. of Daba area the limestone is intercalated with calcareous dolomite, and is 267.6-m thick.
GeoJSON
Fossils
Brachiopods such as Leptodus nobilis, Waagenites sp.; Fusulina such as Yangchienia sp., Nankinella sp.; Corals such as Wentzelella cf. limorica and Iranophyllum splendens; as well as bryozoan, Foraminifera and algae.
Age
Depositional setting
It is interpreted as shallow-sea platform-facies carbonate deposits.
Additional Information
GeoJSON estimate by Runan Yong, Suxiao Li and Wen Li (Chengdu Univ. Tech. students)