Geochronological scale of Upper Proterosoic (Rephean and Eocambrian) of the USSR: present status

A geochronological concept of Pre-Cambrian separation is considered. It is shown that the geochronological scale of Pre-Cambrian should base on the same principles as that of Phanerozoic. The role of isotopic geochronometry in scale plotting results in determination of isotopic age of the boundaries of the earlier developed stratighraphic (chronostratigraphic) scale. The paper summarized all the published data concerning isotopic dating of the boundaries of the Upper Proterosoic part in the stratigraphic scale of the Pre-Cambrian of the USSR. Reliability of isotopic age determination for different boundaries is estimated