Abstract: In this study, the authors identified a sedimentary sequence of calcareous-clastic turbidites through geological survey in Yuanjiang County of central Yunnan Province. The sedimentary sequence section consists of two calcareous-clastic turbidite forms, and contains a series of sedimentary tectonics, such as Boma sequence, graded bedding, oblique bedding, slump structures and flute marks. These sedimentary rocks show low maturity and sorting under the microscope. At the upper section, there exists about a tuffed globular quartzite bed 4m in thickness, whose LA-ICP-MS zircon U-Pb ages are 1102±76Ma and 1713±48Ma(YJgzn-03), and the zircon exhibits the loss of common Pb; another sample of quartz-orthophyre that intruded into the turbidite bed has the LAICP-MS zircon U-Pb ages 349±13Ma and1732±13Ma(YJgzn-02), and the sample without loss of common Pb has the mean age of 1718±30Ma, which could be regarded as the intrusive age of quartz-orthophyre. All of the zircons in the two samples that show the same ages are marked by girdle structure in CL images and Th/U>0.4, characterized by loss of common Pb. According to the zircon ages of tuff and intrusive rocks (quartz-orthophyre), the turbidite bed might have been deposited earlier than 1713±48~1718±30Ma. Based on correlation with the Proterozoic sedimentary beds and Kunyang Group, the authors hold that the sedimentary sequence of calcareous-clastic turbidite the authors studied in this paper should be formed earlier than Kunyang Group, being products of Proterozoic form or even earlier. The authors suggest that it should be named Proterozoic"Manlin Formation"because it is near Manlin Village in Yuanjiang County.