Mengjia Fm
Type Locality and Naming
It was named by the Western Yunnan Geological Party under the Research Institute of Geology of the Academy of Sciences of China in 1965. The naming section is located in the vicinity of the Mengga Village 26 km southwest of Luxi County, Yunnan Province.
Synonym: （勐戛组）; Mengga Fm (spelling), Mali Fm (?)
Lithology and Thickness
Composed of purple sandstones and shales, intercalated with limestones, and being subdivided into three members. Lower member representing purple and brick-red sandy shales, siltstones, calcareous poststones (= fine-grained sandstone) and marl lenses, intercalated with a 12 m thick layer of yellow shales at its base, with a thickness of 477 m. Lower part of the Middle member representing dark-grey dense limestones with oolitic texture associated with a 2 m thick layer of brecciated limestones at its base, while the upper part of the middle member representing grey-white medium-bedded stratified dolomitic limestones, with a thickness of 50 m. Upper member consists largely of purple and dark-violet sandy shales, shales and calcareous poststones intercalated with 4 m thick layers of limestones and sandy conglomerates respectively in its lower part, with a thickness of 315 m.
Relationships and Distribution
Lower contact
It is disconformably underlying the lower Permian Shazipo Fm in type area. Regionally, the next older unit is the Sanchahe Fm sandstones of latest Triassic-earliest Jurassic age.
Upper contact
It is conformably overlying the Liuwan Fm
Regional extent
The formation is distributed in the areas stretching from the Longkan region to the Wanding region of Luxi County, and from the Liuwan region to the Datian Pass of Longling County, Yunnan Province. In the areas of Gengjia, Huangcaobar and Shuifangjie there are also found the occurrences of the formation. In the area of the Datian Pass the upper member of the formation is composed of basalts, while in the Yongde region its lower member is composed of sandy conglomerates, and unconformably overlies the Triassic System.
GeoJSON
Fossils
The formation yields a small amount of bivalve, Gastropod and Ostracod fossils.
Age
Depositional setting
Additional Information