Qoimaco Fm
Type Locality and Naming
It was named by the Regional Survey Party of Qinghai Province in 1987. The naming section is located 7 km southeast of Qoimaco, Tanggula Township, Germu (Golmud) City, Qinghai Province, with its reference section being situated in the areas of Yanshiping and Hot Spring along the Qinghai-Tibet Highway, Qinghai Province (Regional Survey Party of Qinghai Province). Schematic strat column in previous "red Chinese Lexicon" suggests it is the lowest formation in the Yanshiping Gr.
Synonym: （雀莫错组）, Quemocuo Fm (spelling)
Lithology and Thickness
The lower part of the formation is composed of purple medium-, and thick-bedded fine-grained quartz-sandstones, with its basal part consisting of purple thick-bedded conglomerates, with its middle part consisting of purple and grey-green quartz-sandstones and siltstones, and with its upper part consisting of grey-green siltstones, mudstones and marls. It is 1234.4 m thick.
Relationships and Distribution
Lower contact
It is in an unconformable contact with the underlying upper Triassic Jieza Gr or with the lower Permian Kaixinling Gr
Upper contact
Regional extent
The formation is distributed extensively in the areas of Yanshiping and Qoimaco, with a consistent lithology, and with a thickness of 1138-1234 m.
GeoJSON
Fossils
The formation is rich in bivalves of the Bajocian stage as represented by Astarte muhibergi, A. elegans, A. minima, Anisocardia gibbosa, Protocardia truncata, Pleuromya oblita, P. cf. marginata, Vangonia cf. geniculata, Kobayashites hayamii, Oxytoma munsteri and Corbicellopsis schmidti.
Age
Depositional setting
The formation represents littoral in association with lagoon-facies deposits.
Additional Information