Chaofeng Fm
Type Locality and Naming
The type section of the Chaofeng Formation is the Chaoshan section, located near the peak of the Chaoshan Hill (120°13’00” E, 30°26’00” N), about 8 km northwest of the Yuhang District, Hangzhou City, northern Zhejiang Province. The section was remeasured by Luo Zhang et al. from Hangzhou Institute of Petroleum Geology in 1981. In the type section, the formation is 175.10 m thick. The Chaofeng Formation was named by Ju (1978). The name is derived from Chaofeng Peak of Chaoshan Hill in Yuhang District of Hangzhou City, Zhejiang Province. Originally the formation was called Chaofeng Group by Ju (1978) and was lowered in rank as Chaofeng Formation by Song in Yu (1996).
Synonym: （超峰组）
Lithology and Thickness
The Chaofeng Fm is a carbonate sequence. In the type section the formation is divided into three lithologic beds, from bottom up: (1) greyish black, medium-bedded, crystalline powder to aplitic dolomite (34.3 m thick); (2) white massive crystalline-powder dolomite, intercalated brecciated calcareous dolomite (124.60 m); (3) white massive secondary siliceous rock (the primitive rock is possibly dolomite) (16.2 m, no top is known).
Relationships and Distribution
Lower contact
The Chaofeng Fm rests conformably on the underlying Yangliugang Fm
Upper contact
Because of incomplete exposure, its contact with overlying formation is unknown. However, based on the lithologic sequence of the Yuhang area, it is probably overlain by the Ordovician Lunshan Fm
Regional extent
The Chaofeng Formation is exposed in the Jiangnan Slope Area of South China Region, distributed mainly in the transitional areas between the Jiangnan Slope Area and Jiangnan Basin Area, and is sporadically outcrops at Chaoshan of Yuhang District and Zheshan of Xiaoshan District, Hangzhou City, at Xiashi of Haining County, and at Washan of Pinghu County, northern Zhejiang Province, and at Ma’anshan Hill of Kunshan City, southern Jiangsu Province. In these areas the formation is stable in lithology, dominated with light grey dolomite. The dolomitic content of the formation decreases westward with changing facies gradually into limestone of Huayenssu and Siyangshan formations in northwestern and western Zhejiang Province.
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Age
Depositional setting
Additional Information