Nashui Fm
Type Locality and Naming
The type section is located by the Highway between the South of the Nashui Village and the Sanglang area of the Wangmo County about 35 km to the southwest of the Luodian County Town, Guizhou Province. It was named by Xiong Jianfei et al. in 1985.
Lithology and Thickness
Limestone. Composed essentially of dark-grey and grey thin-bedded and medium-bedded weakly silicified micrites, containing bioclastic micrite, intercalated occasionally with black organic-rich claystone, and a small amount of bioclastic grainstone, or grainstone and calciruditic graded-bed limestone lenses. Among them the micrite yields a small amount of Radiolaria, calcispheres and Ostracoda, and is possessed of plastic and drag-slip structures. The bioclastic limestones are all composed of bioclastics and a small amount of lithoclastics which have been transported there from the carbonate platform, with the clastics being irregularly plastically and skewedly concentrated or in an orientated arrangement, and being possessed of positive graded bedding. Thickness is commonly of 20-60 m, and being thicker in the north than in the south.
Relationships and Distribution
Lower contact
Conformable contact with the underlying Nandan Fm (= Xiaolangfengguan Fm).
Upper contact
Conformable contact with the overlying Sidazhai Fm.
Regional extent
The formation is distributed in a region to the south of an alignment of the Ceheng, Wangmo, Ziyun and Luodian Counties, still southerly up to the territory of Guangxi Zhuang Autonomous Region and northerly with a facies change taking place in the middle part of the Houziguan Limestone. In the Saiwa section the formation is composed largely of dark-grey and grey-black organic claystones, secondly of clayey limestone, micritic radiolarian limestone, bioclastic and interclastic limestones and a small amount of radiolarian siliceous rocks and claystones, with the marl yielding primary ammonoid fossils, with a thickness commonly of 100-200 m, and with the greatest thickness reaching as many as 300 m in a narrow and elongated delta area extending from the Shazigou of the Zhenning County to Saiwa of the Ziyun County.
GeoJSON
Fossils
Radiolaria, calcispheres, Ostracoda and ammonoids.
Age
Depositional setting
Additional Information