Tuogemaiti Fm
Type Locality and Naming
Western South Tianshan. The type section is located at two isolated outcrops, 6 km northwest of Village Tuogemaiti, and about 42 km north of Atushi County, Xinjiang. The reference section is at Mt. East Alai.
It was named by No. 13 Xinjiang Geological Team in 1955, and was published by "The Regional Scale of Northwest China-Xinjiang” in 1981.
Lithology and Thickness
Tuogemaiti Fm at Mt. East Alai is divided into Lower (limestone) and Upper (schist) members.
Limestone. The Lower member in the West of Mt. East Alai is composed of dark-gray massive limestone with black cherty interbeds, intercalated with green sericitic schist, tuffaceous sandstone and basic volcanic rock, quartzite and pebble-bearing silty sandstone, and is 1000 m thick.
Schist, limestone. The Upper member in the East of Mt. East Alai has a lower 200 m of black to dark-gray sericitic schist intercalated with thin-bedded limestone, and an upper 200-250 m of dark-gray to light-gray medium- and thick-bedded limestone.
Relationships and Distribution
Lower contact
In the west, this formation unconformably overlies on Silurian.
Upper contact
The top is in a disconformable contact with Lower Carboniferous in the West of Mt. East Alai (column 10); but overlain by the Tangaitar Fm
Regional extent
Lower member of the Tuogemaiti Fm is only distributed in the West of Mt. East Alai and upper reach of Tuoshigan River, and conformably overlies on the Wupatarkan Group of Lower Devonian (column 12 – although map suggests this is East of Mt. East Alai?).
Upper member of the formation is widely distributed in Tangaitar to Tuogemaiti area east of Mt. East Alai, where its upper part is mainly thick-bedded limestone intercalated with a few beds of sericitic quartz schist, yields brachiopods Stringocephalus, Bornhardtina and corals Temnophyllum, Neospongophyllum, etc., and is 400-500 m thick; its lower part is mainly limestone and marl interbeds, the bottom is sericitized schist and calcareous schist, yielding coral Tabulophyllum, brachiopods Indospirifer, Spinatrypa, Productella etc., is 350-400 m thick, and unconformably overlies on Silurian. Further to the east of Wushigunguntielie River, it is composed of grayish-black thin- to medium-bedded limestone intercalated with thick-bedded marble, crystalline limestone and breccia limestone; yields brachiopods Stringocephalus, Ilmenia; and the thickness is more than 1868 m.
In the upper reach of Tuoshigan River, under this member is a set of intermediate volcanic rock intercalated with limestone which yields brachiopods Hypothyridina, Atrypa and coral Favosites shengi, and this unit corresponds to the Lower member.
GeoJSON
Fossils
The Lower member yields corals Cystiphylloides, Coenites ex gr. variabilis, Striatopora saessi, Favosites cf. goldfissi var. eifeliensis, Pachyfavosites aff. erilius, P. ex gr. Polymorphus etc.
The lower part of Upper member yields corals Tryplasma devoniana, T. hercynica; and the upper part yields corals Temnophyllum, Neospongophyllum, Striatopora, Alveolites; and brachiopod Zdimir. The ages of fauna in the Lower and in the Upper members are Eifelian and Givetian, respectively.
Age
Depositional setting
Additional Information