Baifeng Fm
Type Locality and Naming
Named by Guangxi Comprehensive District Geological Survey Bureau in 1975. The type locality is located in Baifeng-hekou, Lizhouwei, Tianlin County, Guangxi; the reference locality is located in Baikang, Baise County, Guangxi.
Synonym: The Middle Triassic strata in western Guangxi have been successively called the “Pingerguan series” (Xu Ruilin, 1933), “Pingerguan Formation” (Zhao Jinke, et al., 1962) and “Pingerguan Group” (Guangxi Institute of Geology, 1962). Guangxi Petroleum Census Team (1961) named the Middle Triassic Anisian strata “Banna Formation” when studying the Lanmu section in Donglan County. Guangxi District Geological Survey Bureau (1975) named it Baifeng Formation and it was determined to be Middle Triassic Anisian.
Lithology and Thickness
It is composed of fine siltstone argillaceous rocks except tuffaceous sandstone or tuffaceous conglomerate at the bottom. It can be divided into two members: Lower member is mainly composed of medium to thick massive fine sandstone interbedded with shale and mudstone or interbedded; Upper member is mainly composed of thin to medium-thick calcareous mudstone with bluish grey green laminated mudstone, interbedded with limestone lens and a small amount of thin bedded fine sandstone or siltstone. The total thickness of this Formation is 1252-6484 m.
Relationships and Distribution
Lower contact
The bottom boundary is marked by tuffaceous clastic rocks. It is conformable contact with the underlying Luolou Gr (Longzhang Fm in schematic stratigraphic column.)
Upper contact
Top boundary is marked by the appearance of bivalve-rich gray-green shale at the bottom of the overlying estuary Hekou Fm.
Regional extent
The formation is widely distributed in western Guangxi and southeast Yunnan, and there are also large areas in Longzhou area of Chongzuo in southwest Guangxi. The thickness of the lower section is 1000~2000 m in Baize area of Tianyang, and the thickest is 4204 m in Baihe area of Napo County. The upper section is generally 800~988 m thick, and the thickness of Baihe area is up to 2280 m.
GeoJSON
Fossils
Ammonoids: Leiophyllites cf. confucii, Balatonites sp., B. balatonicus, B. multisulcatus, Danubites kansa, Hollandites sp., Bulongites sp., Paracrochordiceras sp., Cuccoceras sp., Paraceratites sp., Huishuites sp., Japonites sp., Judicarites sp., Anolcites sp., Beyrichites sp.; Bivalves: Daonella producta, D. bockhi, D. laluensis, D. arzelensis, D. bulongensis, D. udvariensis; Conodonts: Neogondolella excelsa, N. mombergensis, N. cornuta, N. transita, Gladigondolella arcuata, G. tethydi.
Age
Depositional setting
The formation is characterized by flysch rhythms and the development of bedding in the groove mode and the heavy loading mode. It is a typical deep-water turbidity current deposit.
Additional Information