Ertang Fm
Type Locality and Naming
The type section is located from Tuntou Village to Liufeng Forest Farm on the western slope of Liushiling Ridge at Ertang (109° 45'E-23° 44'N) in Wuxuan County, Guangxi. It was named by Yu Changmin and Yin Bao’an in 1978.
[Figure - Location of type section of Ertang Formation with simplified geologic map (top right) and ideal correlation (below right).]
Lithology and Thickness
Limestone. The formation is a set of strata assemblage composed of limestone and clayey limestone, and subdivided into two members. Lower member consists of alternation of thin-bedded limestone and mudstone and shale with few dolomitic limestone containing brachiopods, tabulates, 240 m thick. Upper member composed of medium-thin-bedded limestone with nodular limestone, clayey limestone, shale and few dolomitic limestone yielding tabulate corals, bioherm and brachiopods, 150 m thick..
[Figure - Outcrops of Ertang Formation along the road from Shuanggui to Liufeng showing the Upper (left) and Lower (right) members.]
Relationships and Distribution
Lower contact
The greenish-gray and dark-gray shale at the base of the formation conformably overlies the Shanglun Fm Dolomite.
Upper contact
It is conformable contact with the overlying Guanqiao Fm Dolomite..
Regional extent
The formation is mainly distributed Wuxuan area along the western side of Dayaoshan Mt. From north to south, the mud content may decrease and carbonate content increase..
GeoJSON
Fossils
It yields Brachiopods Howellella fecunda, Reticulariopsis ertangensis, Glyptospirifer sp., Athyrisina sp. Corals Lyrielasma guangxiensis, Xiangzhouphyllum minor, Zonophyllum sp., Tryplasma sp., Favosites sp., Squamofavosites sp. Stromotoporoids Anostylostroma tuntouense, Stramatopora liujinensis, Parallelostroma kuangsiense. Conodonts Eocostapolygnathus perbonus (Phillip) have been reported.
[Figure – Conodont Polygnathus perbonus Branson & Mehl, 1934. lower and upper views.]
Age
Depositional setting
It is interpreted as an open platform facies.
Additional Information