lang=EN-US>Rilonggou-Saishitang region in Xinghai County, Qinghai Province lies in the north of Buqingshan-Animaqing Ocean and is connected to the middle region of Hercynian Kuhai-Saishitang Branch Ocean through the NNE spreading. In the expansion, subduction and closure stage of the branch oceanic basin, a series of NNW and NEE distribution, main tectonic faults were formed. The effects of the geological structures spread to the development of a series of sedimentary basin and the distribution in the branch oceanic basin controlling the formation and distribution of the Early Permian volcanic-formation sedimentary deposits.