Phanerozoic continental crust evolution of the Inner Caucasian Microplate: The Dzirula massif

Abstract

In the Pre-Alpine Dzirula massif of the Inner Caucasian Microplate is coded a wide spectrum of the geodynamic and magmatic events taking place in the region and that's why it represents important and major structure for general geological interpretations. In the given work, on the example of the mentioned crystalline massif evolution are considered processes of the continental crust in Phanerozoic collisional orogens. We consider, that in Variscan consolidation Dzirula massif formations of the Neoproterozoic Pan-African tectonicthermal events are observed, that are organically involved in the evolution processes of the Caucasian Phanerozoic collisional orogen and their role in these processes are probably caused by the migration of lithospheric residues to the north, that are formed as a result of Gondwana northern edge Late Ordovician destruction and opening of Palaeo-Tethys. Within the Dzirula massif, a Gondwana-derived Neoproterozoic gneiss-migmatite complex is situated obductively on ensialic island arc. In this Variscan collision-accretion structure, the crustal thickening and released water caused partial melting of the ensialic island arc, thus generating the granitoid melt, which intruded the overlying gneiss-migmatite complex. By the end of this process, the Dzirula massif resembled typical Phanerozoic continental crust.