Heweitan Gr
Type Locality and Naming
The type section is located at the Heweitan, Hetian County, Xinjiang Weiwuer Autonomous Region. It was named by Xinjiang Regional Stratigraphic Table Writing Group in 1980. When named, they are called the Lower Heweitan Group and the Upper Heweitan Group, respectively representing the Early Triassic strata dominated by carbonate rocks and the Middle Triassic strata dominated by clastic rocks in southwestern Xinjiang. In 1984, the Xinjiang Geological and Mineral Bureau's first district survey team called the original Lower and Upper Heweitan groups the Upper Heweitan group, and the age belonged to the Middle Triassic; in addition, a set of marine carbonate rocks and clastic rocks in the Tianshuihai section is called the Lower Heweitan Group, and its age belongs to the Early Triassic. In 1987, Rao Rongbiao et al. collectively referred to the original Lower and Upper Heweitan Groups as the Heweitan Gr, and classified them as the Middle-Upper Triassic.
Synonym: Heweitan Fm
Lithology and Thickness
It is mainly consisting of light gray, dark gray thin-medium-thick limestone, intercalated with biological limestone, siltstone, fine sandstone, siliceous rock, and a small amount of siliceous limestone, dolomite, marl and carbonaceous siltstone locally. The thickness is 1010 m.
Relationships and Distribution
Lower contact
The Heweitan Gr is false conformable in contact to the underlying Kongkashankou Fm (or Kongkashan Fm on schematic strat column) of late Permian (P3)
Upper contact
Regional extent
The formation is distributed in Ageledaban to Longbaqibaodaban, Xinjiang Weiwuer Autonomous Region. The thickness of the lithology varies greatly. In the Kongka Mountain Pass, the group is dominated by clastic rocks with a thickness of only 76 m; in the upstream of Agledabagou in Taxkorgan County, it is dominated by carbonates, with a thickness of 446 m; in the north of Heitoushan, the group It is still dominated by carbonate rocks, with a thickness of 1516 m; in Longbaqibaodaban, Hotan County, the thickness is the largest, reaching 2337 m.
GeoJSON
Fossils
Bivalves: Daonella aff. indica, Halobia sp., H. cf. talauana, Parahalobia sp.; Corals: Conophyllia sp., Margarosmillia sp., and sea lily Pentagonocyclicus sp.
Age
Depositional setting
It is interpreted as active sandy muddy clastic flysch deposits.
Additional Information