Abstract: Abstract: Neoproterozoic magmatic rocks are widespread on the western margin of the Yangtze block, and their genesis and tectonic setting have long been problems of hot debate. Petrological, geochemical and Sm-Nd isotopic data are reported for Neoproterozoic Kangding-Danba mafic dykes in the Kangdian rift on the western margin of the Yangtze block. This paper deals with petrogenesis and magma source characteristics of these rocks. The rock samples are of tholeiite series, and their geochemical and Nd isotopic characteristics suggest that they were generated in an intraplate setting with variable degrees of contamination of young island arc crust during magma ascending. The magma was generated by partial melting of DM mantle source region within the spinel stability field, and was probably related to Neoproterozoic plume event related to the breakup of Rodinia supercontinent.