The Exotic Inim Block of the Argun Superterrane of the Central Asian Fold Belt: Results of U-Th-Pb Geochronological (LA-ICP-MS) and Sm-Nd Isotopic-Geochemical Studies

摘要

The results of studies indicate that the age of the protoliths of garnet-bearing biotite-sericite-muscovite schists of the Inim Block is 991 Ma, and they are derived from rocks of the Neo-, Meso-, and Paleoproterozoic (as well as Archean) crust. This suggests that the Inim Block is exotic relatively to the Argun Superterrane due to the formation of the protolith of its metasedimentary rocks largely from erosion products of the Early Precambrian continental crust, the presence of which within the Argun Superterrane is not proven. It is not excluded that the Inim Block is a fragment of the Dzhugdzhur-Stanovoi Superterrane implanted in the structure of the Argun Superterrane as a result of Mesozoic tectonic events.