“…It is composed of dislocated Paleozoic terrigenous and terrigenous-carbonate sequences and is usually considered as a fragment of a passive continental margin (e.g., Parfenov et al, 2003;Khanchuk, 2006). However, our recent geochemical data (Sorokin et al, 2010b(Sorokin et al, , 2012 are at odds with this interpretation and indicate that the sediment were accumulated in a passive continental margin during the early stages of formation of the Oldoi terrane and in an island arc or active continental margin setting during the late stages. In this paper, we report the results of Sm-Nd isotope geochemical and U-Pb geo chronological (LA-ICP-MS) investigations of the ter rigenous sequences of the Oldoi terrane, which allowed us to identify the source rocks and, to a first approxima tion, regions from which the sediments were derived and, thus, refine the existing models of the geodynamic settings of their formation.…”