Kaotai Fm
Type Locality and Naming
The type section of the Kaotai Formation is located near the Gaotai Town (107°21’E, 27°37’N), about 35 km south of the seat of Meitan County, Zunyi City, Guizhou Province. In the type section, the formation is 41.5 m thick. The Kaotai Formation was named by Yin et al., (1945). The name is derived from Kaotai (spelled Gaotai in Hanyu Pinyin) Township, Meitan County, Zunyi City, north-central Guizhou Province. Originally it was called Kaotai Limestone by Yin et al., (1945) and was subsequently renamed Kaotai Formation by Lu (1962).
Synonym: （高台组）
Lithology and Thickness
The Kaotai Formation is basically a carbonate sequence, comprising mainly dolomite. The rocks look very much similar to greyish yellow shale after weathering. In the type section it is divided into five lithological beds, from bottom up: 1, grey, thin-bedded sandy to argillaceous dolomite with interbeds of claystone and siltstone (9 m thick); 2, dark grey, medium-bedded striped argillaceous dolomite (5.3 m); 3, dark grey, thick-bedded micritic- to fine-crystalline dolomite (16.1 m); 4, grey, thin-bedded striped dolomite (7.5 m); 5, grey, thin- to medium-bedded sandy to argillaceous dolomite and claystone (3.6 m).
Relationships and Distribution
Lower contact
The Kaotai Fm is in conformable contact with the underlying Chinghsutung Fm. Its lower boundary is defined by the appearance of sandy dolomite at the base of the formation after the disappearance of the oolitic dolomite of underlying Chinghsutung Fm
Upper contact
The Kaotai Fm is in conformable contact with the overlying either Shilengshui Fm or Loushankuan Fm. The upper boundary is defined by the appearance of either the striped dolomite at the base of the Shilengshui Fm or thick-bedded to massive dolomite at the base of Loushankuan Fm.
Regional extent
The Kaotai Formation is exposed in the Yangtze Area of South China Region, distributed over the eastern part of northern Guizhou, southeastern part of Hubei, westernmost and northwestern parts of Hunan provinces, and southern and eastern parts Chongqing Municipality, i.e., over the east margin part of Yangtze Area, South China Region. The formation is relatively stable in lithology.
GeoJSON
Fossils
In the type section the Bed 1 of Kaotai Formation yields trilobites Kaotaia cf. magma, Meitainia suni, Paramecephalus meitanensis, and Solenoparia sp.; and the Bed 5 yields Kaotaia cf. magma, Douposella sp. Meitainia suni, and Paramecephalus sp. In other localities the formation yields additional trilobites Chittidilla, Kuetsingcephalus, Kunmingaspis, Paragraulos, and Sinoptychoparia.
Age
Depositional setting
Additional Information