The First Data on the Age of Metamorphic Rocks of the Synchuga Block of the Jiamusi Continental Massif (Central Asian Orogenic Belt)

The results of U–Th–Pb geochronological studies of zircons from metamorphic rocks of the Amur group of the Synchuga Block of the Jiamusi continental massif are given. It is shown that garnet–biotite–sericite schists of the Amur group have a primary sedimentary origin. The lower depositional age of the protolith can be determined by the age of the youngest zircons from a group with Neoproterozoic ages of ~832 Ma. The upper age boundary of the protolith, apparently, corresponds to the age of metamorphic zircons of ~533 Ma. Thus, the schists of the Amur group of the Synchuga Block are Neoproterozoic in age rather than Early Precambrian, as was accepted earlier.