Lubagou Fm
Type Locality and Naming
The type section is located at Lubagou, 8 km northwest of Luoda in Têwo County, Gansu Province. It was named by Sun Guangyi in 1980 and was formally quoted by Hou Hongfei, Wang Shitao et al in 1988.
Lithology and Thickness
Dolomite. It is composed of brownish-gray iron-bearing dolomite, fine-grained quartz sandstone, gray phyllitized chlorite sericite slate, calcareous slate and interbeds of thin- to medium-bedded micrite, partly intercalated with ferro-dolomite lenses and lenticular to banded microlitic siderite. It is 246.1 m in total thickness.
Relationships and Distribution
Lower contact
It conformably overlies the phyllitized chlorite sericite slate of the Lazigou Fm of Lower and Middle Devonian.
Upper contact
It is conformably overlain by the limestone intercalated with slate of the Xiawuna Fm of Middle Devonian.
Regional extent
The Lubagou Fm is mainly distributed from east of Têwo to Zhuqu, and can be correlated with the Lure Fm exposed at west of Têwo, but can be differentiated from the platform-type deposits of the Lure Fm by its clastic rocks intercalated with carbonate rock of littoral continental shelf facies.
GeoJSON
Fossils
The limestone contains abundant coral Sociophyllum, Utaratuia, brachiopods Indospirifer, Athyrisina.
Age
Depositional setting
It is interpreted as a littoral continental shelf facies.
Additional Information
This formation originally included two different lithological members, of which a lower member similar to the underlying Lazigou Fm in lithology was put into the Lubagou Fm merely because it yielded Frasnian tentaculites. However, according to the principle of lithostratigraphic classification, it is now returned back to being the upper part of the Lazigou Fm.