Xiahuangkeng Fm

The type section is at Xiahuangkeng 50 km east of Qujiang City, northern Guangdong. The Xiahuangkeng Fm is derived from the Xiahuangkeng Series proposed by Nan Yi in 1959.

Synonym: (下黄坑组）

Reference Section:

The reference section is at Jingxihe 2.6 km 115° of Xibei in Qujiang.

The Xiahuangkeng Fm is divided into three parts. Lower part is represented by quartzose sandstone intercalated with quartz sandstone, siltstone, with a black chert bed at the base. Middle part is composed of carbonaceous and muddy shale intercalated with silty shale. Upper part is characterized by carbonaceous, muddy and siliceous shale.

The lower part yields graptolites, and the middle and upper parts yield graptolites of Didymograptus hirundo assemblage and Amplexograptus confertus assemblage (Lai et al., 1982). In Taishan, the Xiahuangkeng Fm yield graptolites of Didymograptus abnormis assemblage, Cardiograptus amplus assemblage and Paraglossograptus proteus assemblage, in ascending order (Li Jijin et al., 1987). In Heyuan and Xinfeng, western Guangdong, the Xiahuangkeng Fm is represented by a 168 m thick flysch sequence of muddy siltstone intercalated with silty mudstone, and is divided into Xibei Member in the lower part and the Hebei Member in the upper part (Nan, 1974; Lai et al., 1982). The Xibei Member yields graptolites of Glyptograptus sinodentatus-Isograptus maximodivergens assemblage and Undulograptus austrodentatus assemblage, and the Hebei Member yields graptolites of Amplexograptus confertus assemblage. Above this member, there is 37 m thick medium-bedded unfossiliferous siltstone equivalent to Pleurograptus elegans zone, indicating an upper boundary higher than that in Qujiang (Lai et al., 1982).