New isotope constraints on the time of formation of the Nersinskii dolerite complex from the Biryusa-Sayan area

New data on the Sm-Nd isotopic composition of the dolerites of the Nersinskii complex that are consistent with the petrographic study and the U-Pb dating of detrital zircon from the overlying sedimentary sequences of the Biryusa-Sayan area are presented. The data obtained indicate the absence of the supposed magmatic event 1.6 billion years ago and clearly indicate the Neoproterozoic age of the intrusions. Their source could have been the metasomatized mantle; after formation, dolerites went through several stages of metasomatism, which was reflected in the evolution of its isotopic systems.