Maocaopu Fm
Type Locality and Naming
The type section is located near Maocaopu Village, 2.5 km north of Zunyi City, Guizhou Province and named by Liu (1942). It is named Maocaopu limestone, which refers to the limestone-dominated strata distributed near Zunyi, Guizhou, between the strata of the underlying "nine-level" shoal shale and the overlying Songzikan layer. [See long discussion of terminology in Additional Information.]
Synonym: Maotsaopu Fm
Lithology and Thickness
It is mainly composed of limestone, dolomite and brecciated dolomite, which can be divided into two members from bottom to top. The lower part of the First member is thin to medium thick layer micritic limestone with dolomitic limestone and oolitic limestone, while the upper part is gray red dolomitic limestone and micritic dolomite. Second member is mainly composed of light gray-red medium to thick layers of dolomite, dolomitic limestone and micritic limestone, with dissolved brecciform dolomite at the top and bottom.
Relationships and Distribution
Lower contact
It is concordant with the underlying Yelang Fm
Upper contact
It is concordant with the overlying Guanling Fm
Regional extent
GeoJSON
Fossils
Fossils are rare, mainly bivalves: Eumorphotis inaequicostata, E. laczkoi, Entolium cf. discites, Costatoria sp.
Age
Depositional setting
Additional Information
Synonym: Maotsaopu Fm
Lithology and Thickness:
It is mainly composed of limestone, dolomite and brecciated dolomite, which can be divided into two members from bottom to top. The lower part of the First member is thin to medium thick layer micritic limestone with dolomitic limestone and oolitic limestone, while the upper part is gray red dolomitic limestone and micritic dolomite. Second member is mainly composed of light gray-red medium to thick layers of dolomite, dolomitic limestone and micritic limestone, with dissolved brecciform dolomite at the top and bottom.
Lithology-pattern: Dolomitic limestone
Relationships and Distribution:
Lower contact:
It is concordant with the underlying Yelang Fm
Upper contact:
It is concordant with the overlying Guanling Fm
Regional extent:
GeoJSON:
Fossils:
Fossils are rare, mainly bivalves: Eumorphotis inaequicostata, E. laczkoi, Entolium cf. discites, Costatoria sp.
Age:
Age span:
Beginning stage: Olenekian
Fraction up in beginning stage: 0.15
Beginning date (Ma):
Ending stage: Olenekian
Fraction up in ending stage: 1.0
Ending date (Ma):
Depositional setting:
Depositional-pattern:
Additional Information
Its age was defined as Middle Triassic. Chen Chuzhen (1960) named the lower part of the Maocaopu limestone as the Lower Maocaopu Group and classified it into the Lower Triassic. The Maocaopu limestone can be divided into Upper Maocaopu Member and Lower Maocaopu Member; and which can be classified into the Middle Triassic Xishui Gr and the Lower Triassic Yalang Gr respectively. Yin Hongfu (1962) suggested that the Lower Maocaopu Member should be abandoned and renamed as Xinglongchang Fm and classified into the Lower Triassic, while the Upper Maocaopu Member should be regarded as the first member of Guanling Fm and classified into the Middle Triassic. In 1964, Fan Jiasong et al. redefined the lithostratigraphic range of Maocaopu Formation, that is, the dolomite-dominated strata between the nine-level beach member of the underlying Yelang Fm and the Mundou ("Green Bean") volcanic-ash rock of the overlying Guanling Formation, and the age was taken from the Early Triassic Olenekian.