Sarmatia-Volgo-Uralia junction zone: Isotopic-geochronologic characteristic of supracrustal rocks and granitoids |
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Authors: | E V Bibikova S V Bogdanova A V Postnikov L P Popova T I Kirnozova M M Fugzan V V Glushchenko |
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Institution: | 1. Vernadsky Institute of Geochemistry and Analytical Chemistry (GEOKHI), Russian Academy of Sciences, ul. Kosygina 19, Moscow, 117975, Russia 2. Geological Institute, Lund University, Lund, Sweden 3. Russian State University of Oil and Gas, Leninskii pr. 65, Moscow, 119991, Russia
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Abstract: | The geochronologic (U-Pb isotopic system of zircons) and isotopic-geochemical (Sm-Nd isotopic system of the bulk rock) studies
were performed along the profile extending from the eastern Sarmatia (in the west) to the Middle Volga megablock of Volgo-Uralia
(in the east), i.e., across the entire junction zone for dating the integration of Sarmatia and Volgo-Uralia, representing
two segments of the East European Craton. It is established that the examined rocks are characterized by the Paleoproterozoic
Nd isotopic model age, which varies from 2.1 and 2.4 Ga, except for some samples indicating a similar age of the crust through
the entire Sarmatia-Volgo-Uralia junction zone. The highly metamorphosed complexes of the granulite and amphibolite facies
constituting the southwestern margin of Volgo-Uralia are Paleoproterozoic, not Archean, in age, contrary to previous views.
Two Early Paleoproterozoic lithotectonic complexes are defined in Volgo-Uralia: South Volga metasedimentary and Tersa metasedimentary-volcanogenic.
The obtained data confirm the asynchronous integration of individual segments into the East European Craton: the integration
of Sarmatia and Volgo-Uralia approximately 2100–2000 Ma ago was followed by the conjunction of this newly-formed continent
with Fennoscandia ca. 1800 Ma ago. |
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