Mesoproterozoic mafic and carbonatitic dykes from the northern margin of the North China Craton: Implications for the final breakup of Columbia supercontinent

The North China Craton (NCC) has figured prominently in recent reconstructions on the Paleoproterozoic supercontinent Columbia. Here we report abundant carbonatitic and mafic dykes from around the giant Bayan Obo rare earth element deposit in the northern margin of the NCC, and present geochemical and isotope geochronological data. The carbonatite (1354 ± 59 Ma) and mafic dykes (1227 ± 60 Ma) have comparable whole rock Sm–Nd isochron ages and Sr–Nd isotope compositions, suggesting a common source characteristic. Their geochemical characters including major and trace elements as well as REE patterns also attest to a common tectonic environment of magma generation and emplacement within a continental margin rift. The extensive mafic and carbonatitic magmatisms are associated with an extensional event that resulted in the formation of the Bayan Obo rift in the northern margin of the NCC, which we correlate with the final stages of fragmentation of the Columbia supercontinent amalgam.

Research Highlights
► Abundant carbonatitic and mafic dykes are found in the Bayan Obo giant REE deposit.
► The detailed petrological and geochemical features of these dykes are reported.
► The isotopic data correlate with a late Mesoproterozoic rift-related magmatism.
► The important implication on the breakup of Columbia supercontinent is proposed.