Geochemistry and geochronology of quartz monzogabbro – monzodiorite – granodiorites of the Potudan pluton (Volga-Don orogen)

This article presents new and summaries of previously published geochemical and geochronological data on rocks of the Potudan pluton and host granitoids of the Kholhol-Repyevka batholith in the central part of the Don Terrane (DT) of Volga-Don orogen. The host granitoids of the Khokhol-Repyevka batholith are assigned to the Pavlovsk granitoid complex, which is widespread in the southern part of the DT. The studied Potudan pluton rocks are differentiated from quartz monzogabbro to granodiorites. They are ferroan, meta-aluminous, and the K2O content displays their relationship to the shoshonite series. For the intrusive complexes of the Don terrane, it is assumed that an enriched heterogeneous source with high contents of alkalis, LILE (large-scale lithophile elements) and LREE (light rare earth elements) is involved, the mantle component is confirmed by increased of MgO, Cr, Ni, Ti, as well as high Sr/Y ratios, (La/Yb)n, (Dy/Yb)n, indicating the deep origin of magmas. The source heterogeneity could have been provided by subduction events about 2.1 Ga. The U-Pb zircon age of crystallization of the Potudan pluton rocks (using the SHRIMP II instrument) is 2061 ± 5.4 Ma and corresponds to the postcollision event in the junction zone of the Sarmatian and Volga-Ural segments of the East European Craton. Association of Potudan rocks with Pavlovsk granitoids in time and space and also morphological features of zircon from various types of rock suites prove the effect of hybridization process during crystallization of the composite batholith. The new data make it possible to expand our understanding of the evolution of crust of the Don Terrane and geodynamic regims of its formation.