Heijianshan Fm
Type Locality and Naming
It was named by the First Party of Regional Geological Survey of Gansu Bureau of Geology in 1966 and published by the Compiling Group of Gansu Regional Stratigraphical Scale in 1980. The type section is located at east of Heijianshan Mt. in Subei Mongol Autonomous County, Gansu Province.
Synonym: (黑尖山组)
Lithology and Thickness
The formation, about 418 m in thickness, is subdivided into two parts. Lower part consists of grey black siliceous slate intercalated with quartzite. Upper part is composed of sandstone and siltstone intercalated with black carbonaceous shale.
Relationships and Distribution
Lower contact
It is in fault contact to the underlying Lower Ordovician.
Upper contact
No upper boundary is exposed. Regionally, the next younger unit is the volcanics of the Gongpoquan Gr of middle Silurian.
Regional extent
It is developed in the area of Heijianshan Mt. Stretching westwards, the formation is also exposed from Tashui-Shuigouzi in Xinjiang, where it is dominated by quartzose sandstone intercalated with siltstone, carbonaceous chert and sandy conglomerate, rests disconformably on the Cambrian and its thickness increases up to 2400-2700 m.
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Fossils
Age
Depositional setting
Additional Information