Hongyanchi Fm
(6), mid-Early Permian
Type Locality and Naming
The type section is located at Hongyanchi to the east of Urumqi City, Xinjiang, and the reference section is situated at Cangfanggou of Yamalik Mt. (Yaomo Mt.) to the west of Urumqi City.It was named by the Regional Geological Survey Party under the Xinjiang Geological Bureau in 1965.
Lithology and Thickness
Clastics. Composed mainly of grey-green fine-grained sandstone, medium- and fine-grained calcareous sandstone, massive sandstone, conglomeratic sandstone and siltstone, intercalated with grey-black and black thin-bedded clayey shale, marl and thin limestone. Thickness is 733 m.
Relationships and Distribution
Lower contact
Conformable contact with the underlying Lucaogou Fm.
Upper contact
Disconformable contact to overlying Quanzijie Fm; hiatus spans Kungurian through early-Middle Permian according to Shuzhong Shen et al. (2019, Permian integrated stratigraphy and timescale of China).
Regional extent
The formation is exposed all over the southern margin of the Jungghariya, with its greatest thickness being seen at the Yamalik Mt., and then getting smaller remarkably up to the Jimusar area.
GeoJSON
Fossils
Abundant bivalve fossils such as Anthraconauta ampla, A. iljinskiensis, Palaeonodonta pseudolongissima, Microdonta subovata, M. plotnikovskensis, etc.; Ostracoda as represented by Darwinula monitoria, Tomiella incondita, Permiana tubercarinata, Fornicaticatilla antorcana, Sinkingenlla jomoeschensis, Klamaeria sinensis, Boabaschamion aplata, etc., as well as spore-pollens as represented by the Cordaitina- Hamiapollenites assemblage, and plant fossils (phytolites).
Age
Depositional setting
It is interpreted as a lake facies.
Additional Information