Establishment of a neostratotype section for the Nanyuan Formation in the Yuanzhuang area, Xianyou, Fujian, China, and revision of its age

The Nanyuan Formation was previously proposed based on a stratotype section at E’zhai-Nanyuan Village, Minhou County, Fujian Province. However, this formation has been verified to be the Early Cretaceous Shimaoshan Group. Thus this section has not been regarded as a stratotype section for the Nanyuan Formation. A neostratotype section for the Nanyuan Formation has been established at Yuanzhuang Village, Xianyou County, during 1:250000 regional geological survey of the Zhouning Sheet, Fuzhou Sheet, Putian Sheet and Quanzhou Sheet. The stratigraphic sequences and rock associations of the Nanyuan Formation have been redefined. The age of the Nanyuan Formation has been redefined as Late Jurassic-initial Early Cretaceous according to the systematic research on the superposed relation of strata, isotopic dating and fossils.