| Abstrakt: |
The authors summarize the available data on the structural-formational zonality of the Urals. Seven megazones of the Ural Fold Belt from west to east have been studied. The paleocontinental sector of the Urals, i.e., the former passive margin of the Baltica/Laurussia paleocontinent includes the Cis-Uralian Foredeep, the West Uralian and Central Uralian megazones. The paleo-island-arc sector, a collage of ophiolites, island-arc, and microcontinents (?), includes the Tagil–Magnitogorsk, East Uralian, and Transuralian megazones. These sectors are separate by the suture zone (the Main Ural Fault MUF). New data on the geochronology of the Bashkirian anticlinorium belonging to the Central Uralian Megazone are presented. Within the Central Uralian Megazone, the Paleozoic facies of the continental rise have been identified for the first time. The Tagil and Magnitogorsk island-arc terranes are correlated. The Tagil terrane began its development earlier and experienced two cycles of magmatism. The Magnitogorsk island arc is characterized by the shorter period of formation, gently dipping and less deep erosional downcut. The ideas, according to which the East Uralian megazone is considered a Madagascar-type microcontinent (Kazakhstan or Mugodzhary), are under discussion. The previously proposed Proterozoic age of the metamorphic rocks of the eastern segment of the Urals has remained unproven. The East Uralian Megazone, a rather young structure, is an integral part of the Ural Fold Belt and did not belong to hypothetical older megastructures. The main stage of folding, tectonic stacking, metamorphism, and granitization in the Ural Fold Belt are dated back to Late Paleozoic. It is shown that the observed latitudinal zonality of the Urals is determined by different present-day erosion depths. The vertical movements that determined the sublatitudinal zonality occurred mainly in the Middle–Late Triassic and were induced by north–south compression. [ABSTRACT FROM AUTHOR] |
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