Jialao Fm

The type section of Jialao Formation is located at Jialao Village near Jiumenchong in Nangao Township, Danzhai County, Qiandongnan Prefecture, Guizhou Province (107°52’E, 26°22’N). It lies about 4 km southwest of the Nangao Town and was measured by Zhang Zhenghua, Zhou Zhiyiand others in 1970. In the type section the Jialao Formation is 85.0 m thick. The Jialao Formation was first published by Nanjing Institute of Geology and Palaleontology (1974). The name is derived from Jialao Village in Nangao Township, Danzhai County, Qiandongnan Miao-Dong Autonomous Prefecture, Guizhou Province. The name was originally appeared in a 1970 manuscript by Zhang Zhenghua, Zhou Zhiyi and others from the Institute of Geology, Guizhou Headquarter of Petroleum Exploration and the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences.

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The Jialao Formation comprises a lower carbonate sequence with clastic interbeds and an upper clastic sequence. In the type section the formation is divided into four lithological beds, from bottom up: 1, black carbonaceous limestone intercalated with carbonaceous and calcareous shale (19.0 m thick); 2, dark grey, thick-bedded argillaceous limestone (13 m); 3, grey calcareous shale intercalated with sandy shale (40.0 m); 4, grey and greyish sandy shale and siltstone (13 m).

In the type section, the Bed 2 of the Jialao Formation yields trilobites Fuchouia prompta and Fuchouia sp.; the Bed 3 yields trilobites Ehmaniella casta, Fuchouia cf. elongata, F. limbata, F. prompta, Jialaopsis latus, Kootenia sanwanensis, K. fida, Metabalangia？sp., and Ptychoparella usualis and brachiopods Acrothele sp., Helcionella sp., and Nisosia sp.; the Bed 4 yields trilobites Ehmaniella casta, Solenopleuropsis sp., and Jialaopsis sp. and brachiopod Helcionella sp.