Structural evolution of the Eastern Anatolian Basins: an example from collisional to postcollisional tectonic processes, Turkey

Abstract

The Eastern Anatolian Basins (EABs) started to develop on a mosaic, made up of forearc deposits of the Eastern Pontide Arc (EPA), continental metamorphic rocks of the Anatolian-Iranian Platform (MP), and obducted ophiolitic units of the North Anatolian Ophiolitic Belt (NAOB) and Southeastern Anatolian Ophiolitic Belt (SAOB). The basement rocks of the East Anatolian Region represent a continental fragment positioned between the EPA to the north and the Arabian Platform to the south. In appearance, it can be said that there are many different basins in the Eastern Anatolian Region. This paper reports on three of them that were studied as a part of the work, defining the setting and structural evolution of the EABs as a whole. These are, from north to south, the Oltu-Balkaya Basin, the Tekman-Karayazi Basin, and the Mus Basin. The EABs started to develop in the beginning of the Maastrichtian age with tectonic subsidence. They then evolved as collisional foreland basins on the AIP and ophiolitic units of the NAOB and SAOB during the Paleocene and Early Eocene period, as well. The fill of these basins is represented by basal conglomerate, shallow marine limestone, and elastic rock units. During deposition of this fill, syncollisional Paleocene peraluminous leucogranitic magmatism developed along the Eastern Pontides. From the Middle Eocene to the Quaternary age, different superimposed postcollisional basins developed over the collisional foreland basin fill. In this time interval, a shallow marine-continental molasse deposition was accompanied with high-K talc-alkaline volcanism, which may be attributed to postcollisional magmatism in the Eastern Anatolian Region. As a result, for the structural evolution of EABs, it can be said that the EABs represent a foreland basin in the Maastrichtian-Early Eocene and superimposed postcollisional basins in the Middle Eocene-Quaternary interval.