Modaoxi Fm
Type Locality and Naming
The type section is at Modaoxi in Xiangtaoyuan, 30 km southeast of Taojiang City, Hunan. The Modaoxi Fm was named by the No. 236 Party of Geology, Hunan Metallurgical Geological Prospecting Corporation (1963), and was published by Central-South Compiling Group for Regional Stratigraphic Scale (1974).
Synonym: (磨刀溪组）
Lithology and Thickness
The Modaoxi Fm is dark gray mudstone intercalated with manganiferous limestone and manganese ore, with black or weathered yellow and light gray shale intercalated with manganese limestone at the base. According to the thin-section study by Fan Jiasong, the manganiferous limestone and manganese ore are volcanic vitric-crystal carbonate rock, representing a sedimentation in a basin or the margin of basin. In the type area, the Modaoxi Fm is 5 m thick.
Relationships and Distribution
Lower contact
It rests conformably on the carbonaceous and siliceous shale at the top of the Yanxi Fm
Upper contact
It is conformably overlain by the dark gray mudstone at the base of the Nanshichong Fm
GeoJSON
Fossils
The Modaoxi Fm yields trilobites Cyclopyge, Ellipsotaphrus, Paraphillipsinella. Wang Xiaofeng et al. (1977) divided the graptolite fauna into Climacograptus corona-C. baragwanathi assemblage in the lower part and C. clingani assemblage in the upper part.
Age
Depositional setting
Additional Information