Huangcaopo Gr
Type Locality and Naming
The type section is at Wuliegai (93°49′00″E, 43°35′30″N) northeast of Barkol County, northern Xinjiang. The Huangcaopo Group was named by No.1 Subteam of No.1 Xinjiang Party of Regional Geological Survey (1958) based on the field work. This term was published by Xinjiang Compiling Group for Regional Stratigraphic Scale (1981).
Synonym: (荒草坡群)
Lithology and Thickness
The Huangcaopo Group is divided into three subgroups. The first subgroup, with an incomplete thickness of 1616 m, is composed of considerably variable internally phyllitic calcareous siltstone and banded marble, with some siliceous mudstone, siliceous slate and minor volcaniclastic rock. The second subgroup, 1550 m thick, is characterized by phyllitic silty mudstone, with abundant calcareous concretions and light green intermediate-acid lava and volcaniclastic rock in the middle part. The third subgroup, with an exposure thickness of 1321 m, is represented by grayish green medium to thick-bedded fine-grained phyllitic tuffaceous sandstone and siltstone with local thin-bedded and lenticular marble (Xiao Bing, 1990). The first and second subgroups are a continuous depositional sequence. In the type area, the group recorded an incomplete thickness of 4487 m.
Relationships and Distribution
Lower contact
Not given.
Upper contact
The third subgroup is generally disturbed by fault at the top, but a clear contact relationship between the third subgroup and the overlying Kekexiongkuduk Fm of Silurian Series is observed northeast of Kelisharbulak northwest of Barkol. Regionally, there is also Silurian of the Baishanbao Fm and Hongliugou Fm.
Regional extent
This stratigraphic unit is seen in Barkol County and Yiwu County, eastern Xinjiang.
GeoJSON
Fossils
Brachiopods Strophonella sp., Isorthis sp., Rafinesquina sp. and Sowerbyella sp. have been found from the second subgroup, and the third subgroup yields trilobite Encrinuroidae, Asaphidae and brachiopod Leptelloidea.
Age
Depositional setting
Additional Information