Bachu Fm
Type Locality and Naming
The type section is located at Kalashayi, Awat County, Xinjiang. It was named by the Petroleum Administration of Xinjiang in 1969, and formally cited in Regional Stratigraphical Scale of Xinjiang in 1981.
Lithology and Thickness
Claystone and Limestone. A suite of carbonate rocks intercalated with clastic formation. The lower member consists of purple-red mudstone intercalated with quartzose sandstone, gypsum and limestone, with tuff at bottom. Thickness 222 m; with little variation in lithology and thickness.
Relationships and Distribution
Lower contact
Conformable contact with the underlying Keziertag Fm (Kiziltag Fm) of upper Devonian
Upper contact
Conformable contact with the overlying Kalashayi Fm
Regional extent
Distributed along the east bank of the Xiaohaizi Reservoir of Bachu County and Kalashayi of Awat County. Drilling has confirmed that this formation is widespread beneath the Cenozoic cover in the lower reaches of the Yarkant and Hotan rivers.
GeoJSON
Fossils
Brachiopods Eochoristites sp., Camarotoechia sp., Schuchertella sp. and Avonia sp.; Gastropod Euomphallus sp. and Trilobite Phillipsia sp. On the north side of the Xiaohaizi Reservoir in Bachu County (Liu Chao’an et al., 1991), the Eochoristites meipentaiensis-Fusella ussiensis (Brachiopod) assemblage and Conodont Siphonodella cf. sulcata have been found at the top limestone.
Age
Depositional setting
It is interpreted as intertidal, supratidal and intertidal lagoon environments.
Additional Information