Sources of detrital zircons from terrigenous deposits in the Yankan terrane of the Mongolian-Okhotsk mobile belt

摘要

This report presents the results of U-Pb-geochronological studies (LA-ICP-MS) of detrital zircons from metasedimentary rocks of the west of the Yankan terrane (one of the largest within the structure of the Mongolian-Okhotsk mobile belt). The performed studies ascertain sufficiently the current notions of the geological development of the terrane. It is shown that the rocks are different in age from the main populations of detrital zircons and in the Sm-Nd isotope-geochemical characteristics. In view of this, one may suppose that these rocks do not belong to the unified stratigraphic series but are included into the structures of different-aged accretionary complexes. The terrigenous deposits of the Baldizhak series, as well as those of the Krestovka and Dzhalinda suites, probably belong to the accretionary complexes formed in front of the southeastern margin of the North-Asian craton. On the contrary, the sedimentary formations of the Preobrazhenovka suite are most likely constituents of the accretionary complex formed near the southern margin of the Amur superterrane. The absence of detrital zircons of Mesozoic age in the treated rocks allows one to assume that the considered accretionary complexes were formed during the Paleozoic.