Scientific publications

The Volga-Ural segment is one of three major structural elements of the East European Platform basement. The Precambrian complexes here are completely overlapped by sedimentary cover. The Nurlat complex is a granulite and gneiss area within the Archean Otradnenskaya series located in the northern part of the Middle Volga megablock of the Volgo-Uralia. Data on the microelement composition of typical enderbite-gneisses of the complex have been obtained for the first time. Further studies are needed to determine the geochemical characteristics of the crystalline schists occurring within the Nurlat complex in minor amounts. The trace element content of enderbitegneisses of the Nurlat complex are similar to that of TTG series rocks. Two groups of enderbite-gneisses were distinguished based on geochemical features and Nd isotope composition. The Lan/Ybn values of the Nur 1 group rocks fall in the 8.3–11.6 (TNd(DM) of 3.7–3.5 Ga) interval; enderbite-gneisses of the Nur 2 group have Lan/Ybn values at 20–21 (TNd(DM) 3.4–3.1 Ga). The Nurlat enderbite-gneisses were compared with enderbites of the Titovsky massif and granitoids of the Bakalinsky massif, which forms the eastern part of the Middle Volga megablock. The protoliths of the Nur 1 rocks (TNd(DM) from 3.7 to 3.5 Ga) probably correspond to the primary volcanic material of the Nurlat complex. In the Neoarchean time, no later than 2.7 Ga, presumably during partial melting of the Nur 1 rocks, there formed enderbites of the Nur 2 complex (TNd(DM) from 3.4 to 3.1 Ga) and enderbites of the Titovsky massif (TNd(DM) = 3.2 Ga). Simultaneously, diorites and leucosomes in migmatites of the Bakaly massif were crystallized.