RIPHEAN RIFTING AND MAJOR PALAEOPROTEROZOIC CRUSTAL BOUNDARIES IN THEBASEMENT OF THE EAST EUROPEAN CRATON - GEOLOGY AND GEOPHYSICS

The East European Craton, which occupies the northeastern half of the European continent, is characterized by the presence of giant, even tr anscratonic systems of Riphean (Meso- to Neoproterozoic) rifts (aulaco gens). The largest of these Riphean rift systems tend to follow the co urse of Palaeoproterozoic sutures and junction zones that subdivide th e craton into three crustal segments with autonomous development histo ries. These segments, named Fennoscandia, Volgo-Uralia and Sarmatia, a re marked by distinct T-MAGSAT anomalies. Genetically, the intersegmen t junction zones represent different types of collisional and accretio nal interaction between the component crustal segments of the craton. In accordance with this, the Riphean rift systems vary in width, the p resence or absence of Moho uplifts, and other properties like, for ins tance, heat flow values. However, all of them follow belts of weakly m agnetized crust studded with local magnetic maxima due to the presence of mafic rocks associated with the rifting. The rift system-intersegm ent junction zone relationships, in consequence, similarly represent a range of variation and cannot be referred to one single model.