The radiogenic isotope characteristics of dikes and sills associated with the Mesoproterozoic Midcontinent Rift near Thunder Bay, Ontario, Canada

► New radiogenic isotope data are presented for intrusive rocks of the Midcontinent Rift. ► Negative ɛNdT are consistent with contamination of a plume-related source by older crustal material. ► Contamination by subcontinental lithospheric mantle is thought to have occurred in all units. ► Selective contamination by host country rocks during emplacement has occurred in some units.