LOCAL, REGIONAL, AND CORRELATION SCHEMES FOR THE PRECAMBRIAN OF KARELIA AND KOLA-PENINSULA - THE HISTORICAL-METHODOLOGICAL ANALYSIS

Stratigraphic investigations of the Precambrian in Karelia and the Kol a Peninsula, which are the type area for the pre-Riphean part of the P roterozoic of northern Eurasia, demonstrate a priority of local strati graphic scales over regional and interregional schemes and the prime s ignificance of stratotypes of stratigraphic units and their boundaries for substantiating scales of any rank. Data on the structure and subd ivision of three pre-Riphean complexes (Saamian, Lopian, and Karelian) of the eastern Baltic Shield are summarized, and a system of subordin ate regional subdivisions of two upper complexes assigned to the Upper Archean and the Lower Proterozoic is considered. Attempts to substant iate the event-reflecting boundaries of these subdivisions by isotopic -geochronological data are discussed. The previous studies resulted in the elaboration of the regional chronometric scale only for the Karel ian, corresponding to the middle part of the general Precambrian seque nce in the region. This scale should be improved in parallel with the regional chronostratigraphic scale.