Abstract:Objectives: Based on the 1∶50000 regional geological survey, the authors have newly found intercalation of nodular basalts and tuff in Heishan formation of Dongchuan group in Lufeng area.In this study, the isotopic age of the newly found nodular basalts and tuff was determination for the first time in this area. Results: The weighted mean ages of zircon UPb in Spherical basalt and tuff were measured by LAICPMS technique to be 1678±10 Ma and 1572±19 Ma respectively.The SiO2 content of the Spherical basalt is between 40.83 and 52.56%, δEu has a positive anomaly, large ion lithophile elements Rb, Ba and high field strength elements Nb, Ta, Th and other incompatible elements are relatively enriched.The whole rock geochemistry is shown as lowtitaniumspotted marine basalt in the continental plate, formed in an extended structural environment. Conclusions: Our results indicate that Heishan Formation was deposited in early Middle Proterozoic, probably because of the splitting of the Columbia supercontinent.This study may provide a new evidence of the sedimentary age, sequence and tectonic setting of Dongchuan group, and provides an chronological constraint for the entire Precambrian stratigraphic framework in the central of Yunnan.