4-Concluding Summary  
Geological field observations and the geophysical data suggest the presence of an ophiolitic mélange-accretionary complex under the cover sequence of eastern Anatolia (A in fig 11-I). The eastern Anatolian volcanic and sedimentary cover units were piled up during the closure of the NeoTethyan Ocean that was located between the Pontide arc to the north, and the continental slivers drifted away from the Arabian Plate to the south (e.g., Şengör and Yılmaz1981). The Upper Cretaceous-Lower-Middle Eocene deep-sea sedimentary rocks, associated genetically with the ophiolitic mélange, indicate that the NeoTethyan oceanic lithosphere survived during this period and was finally eliminated from entire eastern Turkey by the Late Eocene. Continental fragments of various sizes were tectonically incorporated into the mélange prism, possibly during the growth of the accretionary complex.
The northward advance of the Arabian Plate continued after the elimination of the oceanic environment. The mélange-accretionary prism that occupied a large terrain behaved like a wide and thick buffer unit, which did not allow a head-on collision of the bordering continents (cf., the Turkic type orogen of Şengör and Natalin 1996). The northward advance of the Arabian Plate that continued after the initial stage of the collision caused shortening deformation. It began squeezing the eastern Anatolian accretionary complex. As a result, eastern Anatolia was elevated above the sea during the Late Eocene-Oligocene. An irregular topography was developed on the elevated land as indicated by coarse‐grained thick Upper Eocene-Oligocene terrestrial conglomerates deposited in irregularly developed narrow depressions) (B in Fig 11-I). The rough topography was smoothened, and the region subsided steadily during the Late Oligocene-Early Miocene when an epeiric sea invaded the region again (Yılmaz 2017 and the references therein). This is evidenced by the low-energy marine sediments laid down on the Upper Eocene-Oligocene terrestrial sedimentary rocks. The smooth topography survived during the Early-Middle Miocene. Shallow marine limestones (the Adilcevaz Limestone) were deposited above the fine-grained marine sediments (C in Fig 11-I) (Şaroğlu and Yılmaz 1986; Bedi and Yusufoğlu 2018). The limestones graded upward into evaporates and lacustrine limestones during the Late Miocene (Fig 3 and D in Fig 11-I). The gradual transition observed in the entire eastern Anatolian region reveals that interconnected lakes were developed over the elevated land following the disappearance of the sea (Şaroğlu and Yılmaz 1986; Yılmaz 2017). This event may also be interpreted that the eastern Anatolia began to rise as a coherent block (en mass) during the Late Miocene (Phase I, Fig.11-I). Following the disappearance of the interconnected lakes, the elevated land underwent a severe denudation phase, which formed a flat‐lying erosional surface above the Upper Miocene lacustrine limestones (ES in Figs.11-I and the accompanying photo A1) (Yılmaz 2017). The smooth topography disappeared after this period. Various sediment packages were formed in separate depressions from this Late Pliocene onward (Phase II, Figs 11-II).
Entire eastern Turkey, including the Pontide and the Arabian Platform has behaved as an interconnected tectonic entity since their tectonic amalgamation. Paleomagnetic studies and the GPS data support this conclusion, which show that eastern Anatolia has been deformed together with the surrounding tectonic entities since the Late Miocene following the collision of the Arabian plate with the Anatolian blocks (Reilenger et al. 2006; Şengör et al 2008; Çinku et al. 2014; 2016; Gürer et al 2017; Bakkal et al 2019).
The continuing N-S compressional stress caused a complex pattern of structures in the Eastern Turkey (Fig. 4A). The rigid continental crust underlying the peripheral mountains accommodated the N-S compression by elevating faster (0.2-0.3 mm/y) than the eastern Anatolian plateau (0.1-0.2 mm/y). This is possibly because of the blocks and matrix of the ophiolitic mélange underlying eastern Anatolia partly absorbed the compression.
Starting from the Late Pliocene-Pleistocene big scale folds and thrusts began to form in the eastern Anatolia (phases III and IV; Figs 11-III and 11-IV) and the accompanying photos C1 and D1). The peripheral mountains were thrust over the eastern Anatolian plateau (Fig 2; 5A and 5C). Two narrow, fault-bound chains of E-W trending depressions were formed along the thrust fronts as intermountain or ramp basins (Fig1 and Figs 5A; 5B and 5C). The boundary faults give the young basins their distinct rhombohedral or parallelogram geometrical patterns (Fig 5B).
When the N-S compression and associated shortening reached an excessive stage, which could no longer be accommodated within the volume of eastern Anatolia, the stress permutation occurred. This led to the development of two transform faults, the North Anatolian Transform Fault (NATF) and the East Anatolian Transform Fault (EATF) (Figs 1 and 2) (Şengör 1979; Şengör and Kidd 1979; Şengör and Yılmaz 1981; Çemen et al.,1993 and Yılmaz 2017). They defined an independent tectonic entity, the Anatolian Plate, which began escaping away from the area of convergence to transfer part of the north‐south compressional stress to the west (Mc Kenzie 1972; 1978; Şengör 1979; Şaroğlu and Yılmaz 1991; Şengör and Yılmaz 1981). The escape tectonics and associated lateral extrusion initiated a new tectonic regime in Anatolia and the surrounding regions known as the Neotectonics, which determined the development of the major morphotectonic entities in the peripheral mountains and the eastern Anatolian High Plateau (Yılmaz 2017). This event also caused anticlockwise rotations of the semi-independent fault-bounded blocks of Central Anatolia (Yılmaz 2017).
According to geophysical data lithospheric mantle under East Anatolia is very thin. Almost the whole thickness of the mantle lithosphere was removed from the overlying thickened crust (e.g., Barazangi et al., 2003). The space created was filled with a hot, upwelling asthenosphere, which produced mantle-derived magmas. The volcanic activity began sporadically during the Late Miocene and intensified about 5–6 Ma ago. The volcanoes were commonly developed above the extensional openings associated with the basin boundary faults. The volcanic edifices covered the entire plateau as a thick blanket (Yılmaz, 1990; Yılmaz et al., 1987, 1998; Pearce et al., 1990; Keskin, 2007; Keskin et al., 2012).
The north-directed compressional stress is actively deforming eastern Turkey. This is evidenced by GPS measurements (e.g., Reilenger et al., 2002) indicating that the high plateau and the peripheral mountains are still elevating, and the Anatolian Plate’s westward escape is continuing at an about 20 mm/y rate. This continuing deformation may be regarded as the late-post tectonic phase of the orogenic development.