Zhaobishan Fm
Type Locality and Naming
Kuruktag region. The Zhaobishan Fm was named by Zhu Chengshun, Ye Yongzheng et al. (1957), which was introduced by Gao Zhenjia et al. (1981). The type section is located in Zhaobishan (Heishan) area, Yuji County, Xinjiang Weiwuerzhu Zizhiqu (Xinjiang Uygur Autonomous Region). The reference section is located in Xishankou and Yulegunbulak area, Xinjiang Weiwuerzhu Zizhiqu (Xinjiang Uygur Autonomous Region). Lower formation of the Kuruktag Gr (2 of 9).
Synonym: （照壁山组）
Lithology and Thickness
The Zhaobishan Fm consists mainly of thin- to thick-bedded neritic clastic rocks. In the Lower part are gray medium- to thick-bedded arkose, gritstone and pebbly sandstone with argillite, fine-grained sandstone and siltstone. In the Upper part are gray, dark gray and gray-green argillite and silty shale with fine-grained sandstone with occasional sandy conglomerate lenses. Its lithology and thickness are both rather stable. It's 360-560 m thick in general, but thickens in Kestanbulak on north slope of Xingditag to Tikebuladahuang, up to 1192 m.
[Figure: Stratigraphic Column of the Kuruktag Gr]
Relationships and Distribution
Lower contact
The base of the formation shows a conformity or facial change with the underlying Beiyixi Fm in many places. But in places where the volcanic rocks of Beiyixi Fm is very well developed (e.g., around eastern Kuruktag, where the volcanic rock is 1407 m thick), the Zhaobishan Fm is missing and the Atetonggou Fm directly overlies the volcanic Beiyixi Fm in an unconformity.
Upper contact
The top of the Zhaobishan Formation is overlain by the Atetonggou Fm.
Regional extent
Kuruktag region. The formation is rather widespread form the Kalatiekenwula Mountain north of Korla on the west, going eastward to Xishankou and Aletongtag in the northeastern part of Yuli County, and stretching eastward to Moqinkuduk, Xingditag, Zhaobi Mt., Xinggertag, until Yetemubulak, Pargangbulak and Yulegunbulak south of Shanshan County.
GeoJSON
Fossils
Microplants yields in the finer intervals of the coarse-grained clastic rocks, include Asperatopsophosphaera baulensesis, A. umishanensis, A. gigatea, A. incrassa, Trachyspharidium sp., Pseudozonosphaera verrucosa, etc.
Age
Depositional setting
Additional Information
A whole-rock isochron U-Pb date of 753±30 Ma has been obtained from the gray-green argillite in the basal part of the formation in Xishankou (western pass) of western Kuruktag (Zhu Jiechen et al., 1987).