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 (AIP), and obducted ophiolitic units of the North AnatolianOphiolitic Belt (NAOB) and Southeastern Anatolian Ophiolitic Belt (SAOB). The basement rocks of the East Anatolian Region representa continental fragment positioned between the EPA to the north and the Arabian Platform to the south. In appearance, it can be saidthat there are many different basins in the Eastern Anatolian Region. This paper reports on three of them that were studied as a partof the work, defining the setting and structural evolution of the EABs as a whole. These are, from north to south, the Oltu-BalkayaBasin, the Tekman-Karayazı Basin, and the Muş Basin. The EABs started to develop in the beginning of the Maastrichtian age withtectonic subsidence. They then evolved as collisional foreland basins on the AIP and ophiolitic units of the NAOB and SAOB duringthe Paleocene and Early Eocene period, as well. The fill of these basins is represented by basal conglomerate, shallow marine limestone,and clastic rock units. During deposition of this fill, syncollisional Paleocene peraluminous leucogranitic magmatism developed alongthe Eastern Pontides. From the Middle Eocene to the Quaternary age, different superimposed postcollisional basins developed overthe collisional foreland basin fill. In this time interval, a shallow marine-continental molasse deposition was accompanied with high-Kcalc-alkaline volcanism, which may be attributed to postcollisional magmatism in the Eastern Anatolian Region. As a result, for thestructural evolution of EABs, it can be said that the EABs represent a foreland basin in the Maastrichtian-Early Eocene and superimposedpostcollisional basins in the Middle Eocene-Quaternary interval.