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Neoproterozoic metamorphism and deformation at the southeastern margin of the East European Craton,Uralides, Russia
Authors:Email author" target="_blank">U?A?GlasmacherEmail author  W?Bauer  N?Clauer  V?N?Puchkov
Institution:(1) Forschungsstelle Archäometrie der Heidelberger Akademie der Wissenschaften am Max-Planck-Institut für Kernphysik, Postfach 103980, 69029 Heidelberg, Germany;(2) Geologisches Institut, RWTH Aachen, Wüllnerstrasse 2, 52056 Aachen, Germany;(3) Centre de Géochimie de la Surface (CNRS-ULP), 1 rue Blessig, 67084 Strasbourg, France;(4) Geological Institute of the Ufimian Geoscience Center, Russian Academy of Sciences, Karl Marx Str. 16/2, 450000 Ufa, Russia
Abstract:The eastern margin of the East European Craton (EEC) has a long lasting geological record of Precambrian age. Archaean and Proterozoic strata are exposed in the western fold-and-thrust belt of the Uralides and are known from drill cores and geophysical data below the Palaeozoic cover in the Uralides and its western foredeep. In the southern Uralides, sedimentary, metamorphic and magmatic rocks of Riphean and Vendian age occur in the Bashkirian Mega-anticlinorium (BMA) and the Beloretzk Terrane. In the eastern part of the BMA (Yamantau anticlinorium) and the Beloretzk Terrane, K-Ar ages of the <2-µm-size fraction of phyllites (potassic white mica) and slates (illite) give evidence for a complex pre-Uralian metamorphic and deformational history of the Precambrian basement at the southeastern margin of the EEC. Interpretation of the K-Ar ages considered the variation of secondary foliation and the diagenetic to metamorphic grade. In the Yamantau anticlinorium, the greenschist-facies metamorphism of the Mesoproterozoic siliciclastic rocks is of Early Neoproterozoic origin (about 970 Ma) and the S1 cleavage formation of Late Neoproterozoic (about 550 Ma). The second wide-spaced cleavage is of Uralian origin. In the central and western part of the BMA, the diagenetic to incipient metamorphic grade developed in Late Neoproterozoic time. In post-Uralian time, Proterozoic siliciclastic rocks with a cleavage of Uralian age have not been exhumed to the surface of the BMA. Late Neoproterozoic thrusts and faults within the eastern margin of the EEC are reactivated during the Uralian deformation.
Keywords:Metamorphism  K-Ar dating  Neoproterozoic  Southern Urals  Eastern margin East European Craton
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