Geodynamic regimes in the precambrian of the urals

摘要: Abstract Of all Precambrian rocks in the Urals late Proterozoic is best represented. The Archaean and lower are reconstructed from separate blocks (massifs) which roughly correlated with crystalline basement of adjacent platforms. Radiometric dates for majority early exceed 2 Ga. Features very old (2.9 Ga) protocrustal material have been identified grey gneiss complexes. represent remnants charnockite-granulite migmatite-amphibolite complexes, geodynamic regime their generation most primitive does not occur later periods geological history. Karelian age appear to be relics nongeosynclinal mobile belts. Their petrochemical characteristics REE patterns suggest rift-related conditions formation. Late deposits (1650-590 Ma) comprise thick terranes, both at western slope axial zone Urals. Revision rock associations disclosed that these terranes were previously wrongly interpreted as geosynclinal formations. They consist platform sediments include magmatic typical zones diaschysis (tectonomagmatic activation) rifting. Recurrent rifting Elsonian, Grenville Baikal (Assynthian) cycles diastrophism was responsible crustal extension thinning, followed by complete continental breakup development oceanic basins Palaeozoic only. Extension crust during dynamometamorphism under different temperature dropping lithostatic pressure. Blastomylonites schists produced this process mistaken products orogenic metamorphism. considered evidence occurring similar those Palaeozoic. Diaschysis probably predominant regimes resulted destruction or extensive reworking original variable degrees accumulation volcano-sedimentary terrigenous rifted-depressional successions. There no reliable existence an basin