Tonggen Fm
Type Locality and Naming
A reference section is in the subsurface on the basis of well Le-4 at east of Dale Village in Xiangzhou County, drilled by Guangxi Petroleum Team. It was named by Bai S.L. & Ning Z.S. in 1982.
Lithology and Thickness
Lower part of 110 m in thickness consists of fine-grained dolomite, dolomitic limestone, clayey limestone with shale and mudstone. Upper part, 84 m thick, consists of alternation of bioclastic limestone and mudstone with a bed of algal detrital limestone.
Relationships and Distribution
Lower contact
Conformable contact with the underlying “Yukiang Fm”. The contact being marked by the sharp change from fossiliferous mudstone below to dolomite above. On chart (Hongfei Hou, Apr 2021), this underlying unit is Lianhuashan Fm.
Upper contact
Upper contact with overlying Luomai Fm is unknown
Regional extent
This formation is mainly distributed in the Dale area, west side of Dayaoshan Mt.
GeoJSON
Fossils
It contains Bivalves Paracyclas sp., Pholadella sp., Mulationella sp., Modiomorpha sp., Limopteria sp., Leptodesma sp.; Gastopods Orthonota sp.; Brachiopods Howellela sp., Orientospirifer wangi, and trilobite fragments
Age
Depositional setting
It is interpreted as a shallow subtidal sedimentary environment.
Additional Information