Lithospheric structure of the Eastern Anatolia and Caucasus region

This dissertation investigates the lithospheric structure of the Eastern Anatolia and Caucasus region through an integrated approach employing Two-Plane Wave Tomography (TPWT), Ambient Noise Tomography (ANT), P-wave Receiver Functions, and joint inversion of Receiver Functions with Surface Waves, utilizing new data from the CNET (Caucasus Seismic Network) seismic experiment. The tectonic framework of the Greater Caucasus, Lesser Caucasus, and Eastern Anatolia is predominantly shaped by the continental collision between the northward- moving Arabian Plate and the Eurasian Plate. This ongoing convergence has resulted in the formation of the 1,500-meter-high Eastern Anatolian Plateau, a diffuse deformation zone along the plate boundary, and Mount Elbrus (5,642 meters), the highest mountain in Europe (Philip et al., 1989; Reilinger et al., 2006). Comparisons are drawn to earlier stages of continent--continent collision, such as between the Indian and Eurasian Plates, to enhance our understanding of mountain-building processes in similar tectonic settings (Şengör et al., 1979). The extended TPWT results span from Eastern Anatolia to the Caucasus, providing an updated and refined model compared to Skobeltsyn et al., (2014). Integration of ANT enhances depth resolution at crustal levels, while P-wave receiver functions are utilized to analyze discontinuity structures. The joint inversion of receiver functions with combined ANT and TPWT data yields a high-resolution S-velocity structure from the surface to 100 km depth. Key findings include the identification of a low-velocity zone in Eastern Anatolia across all depths, suggesting asthenospheric upwelling and a thin mantle lid at approximately 100 km depth near the Lithosphere-Asthenosphere Boundary (LAB). Crustal thickness increases from south to north in Eastern Anatolia, with possible crustal thickening observed in the Lesser Caucasus. In the eastern Greater Caucasus, evidence points to a northward-dipping flat ongoing subduction, and a potential new subduction zone may be forming in northern Iran, also oriented northward. The weak, low-velocity crust beneath the eastern Greater Caucasus indicates strain weakening due to flexural loading, which facilitates the formation of thick sedimentary rock layers reaching up to 15-18 km in eastern Georgia, central Azerbaijan and potentially deeper in South Caspian. Crustal thickening in Lesser Caucasus is also evident from joint inversion results.