Biexibastao Fm
Type Locality and Naming
Western Tianshan. The Biexibastao Fm was named by Wang Jingbin et al., in 1982 and formally published in 1985 (Wang Jingbin, 1985). The typical section is located in Biexibastao area of Kokirqin Mountain in Jinghe County, Xinjiang Weiwuerzhu Zizhiqu (Xinjiang Uygur Autonomous Region). Middle formation (3 of 6) of Kiaketi Gr).
Synonym: （别西巴斯套组）
Lithology and Thickness
The Biexibastao Fm is dominantly composed of gray massive tillite (diamictite) and gray-white pebbly varvite and pebbly sandy dolomite, with the latter commonly substituted along strike by massive tillite. Locally, the basal part is composed of pebbly sandy dolomite intercalated with dark gray pebbly silty shale and pelitic fine sandstone bearing obvious micro-beddings. The total thickness varies from 9.7 to 55 m
Relationships and Distribution
Lower contact
It disconformably overlies (locally conformably) the Tulasu Fm
Upper contact
It is conformably overlain by the Kayingdi Fm
Regional extent
Western Tianshan. With a limited distribution, the Biexibastao Fm is exposed in Tarqiat area of Kokirqin Mountain in the southwest of Jinghe County in Xinjiang Weiwuerzhu Zizhiqu (Xinjiang Uygur Autonomous Region)
GeoJSON
Fossils
The Biexibastao Fm yields microplants Pterospermopsis aff. oculatus, Trematosphaeridium sp. etc.
Age
Depositional setting
With a variable lithofacies and thickness, the pebbles in pebbly varvite and pebbly siltstone display some characters of the dropstones.
Additional Information