Tardetao Fm
Type Locality and Naming
The type section is located in the western segment of the Awulale Mt., Ili, Xinjiang. It was named by the 9th Expedition under the Xinjiang Geological Bureau in 1982.
Lithology and Thickness
Volcanics and Clastics. It is divisible into the Lower and Upper subformations. The Lower Subformation is composed of light-grey and purple tuffaceous siltstone, quartz-andesitic porphyrite, acidic tuff, basaltic andesitic porphyrite, pyroxene-andesitic dacite and rhyolite, with a thickness of 2406-3115 m. The lower part of the Upper Subformation is composed of unequal interbeds of purple and brick-red tuffaceous sandy conglomerate, tuffaceous siltstone, fine grey-green andesitic porphyrite, basaltic andesitic porphyrite and tholeiite, intercalated with kalirhyolitic porphyrite, brecciated lava and volcanic breccia, with a thickness of 3672-5301 m. The Upper Subformation is in a disconformable or an effusive unconformable contact with the Lower Subformation.
Relationships and Distribution
Lower contact
Disconformable with the underlying Upper Carboniferous Series (Keguqinshan Fm)
Upper contact
Disconformable with the overlying Xiaoshansayi Fm of the Middle Permian Series
Regional extent
Distributed in the western segment of the Awulale Mt. of Ili region, and the area to the north of Yining City, Xinjiang.
GeoJSON
Fossils
Upper Subformation yields such Plant fossils (phytolites) as Paracalamites sp., Carpolithus sp., Calamites sp., Radicites sp., and spore-pollen fossils.
Age
Depositional setting
It is interpreted as continental volcanic effusive deposits.
Additional Information