Bajiaoqing Fm
Type Locality and Naming
The type section is located at Bajiaoqing Village, SE 4.5 km of Wuzhu Town, western Guangnan County, Wenshan Zhuangzu and Miaozu Zizhizhou. A No. G323 highway passes through in the south of Guannan, which links Bajiaoqing by a country road from Laowujia, about 2 km distance. It was named by the Second Team of Yunnan Regional Geological Survey in 1976 and quoted by Jin Sanyu in 2005.
Figure Location map showing the type section of Bajiaoqing Formation (red triangular).
Lithology and Thickness
Dolomitic limestone. It was described as grayish black clayey limestone intercalated with dolomitic limestone and dolomite, 49.55 m thick in the type section. Northeastward to Jiuke Village the lithology includes dolomite with few siliceous nodules in the upper part, 48.67 m thick, and medium-thin bedded clayey limestone intercalated with few thick-bedded dolomite in the lower part, 64.20 m thick.
Relationships and Distribution
Lower contact
The formation is in a conformable contact with the underlying Pojiao Fm
Upper contact
Overlain by thin- to medium-bedded limestone bearing-siliceous bands and nodules of Daliantang Fm, but the upper boundary is not well defined
Regional extent
It is widely distributed in the deep-water carbonate facies of southeastern Yunnan but in most sections it is not recognized. The formation has been quoted in the Changputang section of Wenshan, where the lithology mainly consists of bioclastic micritic limestone with thick-bedded to massive dolomitic limestone containing more coral fossils, 175 m thick, beneath the Daliantang Fm (Jin, 2005).
GeoJSON
Fossils
In Changputang section of Wenshan it contains Corals Cystiphylloides mirabile, Siphonophrentis angusta, Lyrielasma aggregatum, Radiophyllum solaris, Enterolasma yunnanense; Brachiopod Dicoelostrophia punctate, Rostrospirifer tonkinensis; Conodonts Polygnathus gronbergi, P. nothoperbonus.
Age
Depositional setting
The lithology and fossil are indicatives of open platform sedimentary environments.
Additional Information