Gubi Fm
Type Locality and Naming
The type section is located near Gubi Village of Liujing in Hengxian County, Guangxi. It was named by Kuang Guodun, Zhao Mingte and Tao Yebin in 1989.
[Figure Map showing the location (redline F) of Gubi Formation at Liujing]
Lithology and Thickness
Limestone. Lower and Middle parts are characterized by thin- to medium-bedded bioclastic and detrital limestone with horizontal and wavy argillaceous laminae or bands, intercalated with gray thin-bedded nodular limestone. A few siliceous nodule, chert and breccia limestone occur in the upper part. It is 77 m thick in type section. A reference section exposed in the Qifengzhen of Guilin consists of oncolite, banded clayey limestone, breccia limestone and peloidal and algal grainstone with numerous brachiopod beds, more than 300 m thick.
[Figure Outcrop showing the bioclastic limestone of Gubi Formation with brown wavy argillaceous laminae indicating a sliding structure.]
Relationships and Distribution
Lower contact
The base is banded clayey limestone, which differentiates this formation easily from its conformable contact to the underlying thick-bedded calcirudite of the Mintang Fm.
Upper contact
It is disconformable contact with the overlying Rongxian Formation with a basal breccia limestone.
Regional extent
GeoJSON
Fossils
The lower and middle parts contain coral Truncicarinulum; brachiopod Tenticospirifer and stromatoporoids. The conodont Polygnathus asymmetricus occurs at the bottom, and Palmatolepis linguiformis occurs at the top.
Age
Depositional setting
It is interpreted as a platform margin or upper slope facies.
Additional Information