Koksu Gr
Type Locality and Naming
Western Middle Tianshan. The Koksu Gr (Kekesu Gr) was named by Tan Hongbing et al. in 1977. The type locality is on east bank of Kekesu River Valley, south of Tekes County seat, Xinjiang Weiwuerzhu Zizhiqu (Xinjiang Uygur Autonomous Region).
Synonym: （科克苏群）, Kekesu Gr
Lithology and Thickness
The Koksu Gr is composed of a Si-Mg-bearing carbonate rock association, dominated by dolomite, crystalline limestone and limestone, intercalated with quartzite, locally P-bearing, with conglomerate occurring in basal part. It is rich in stromatolites, forming stromatolite reef in stratified shape, which is the distinct character for the group. It recorded over 487 m thick.
Relationships and Distribution
Lower contact
There is an obvious disconformable or locally unconformable break between it and underlying Tekes Gr.
Upper contact
Disconformable overlain by the Kushitai Gr of Tonian
Regional extent
Western Middle Tianshan. The Koksu Group widely spreads in Halajun Mt., Borohoro Mt., and Ilinhabirgan Mt. It is rather stable in lithological character, but changeable greatly in thickness. In east segment of Tianshan Mountains, the group has stromatolites and minor microplants. It is recorded as over 5000 m thick, but in the west segment of Tekes region, it is only 487 m thick.
GeoJSON
Fossils
The stromatolites are: Baicalia cf. prima, B. cf. baicalia, Collenia f., Anabaria f., Tungussia cf. nodosa, T. cf. confusa, Conophyton f. The microplants: Pseudozonosphaera sinica, Trachysphaeridium simplex, Asperatopsophosphaera umishanensis, A. bavlensis.
Age
Depositional setting
Additional Information