Quaternary uplift of the northern margin of the Central Anatolian Plateau: New OSL dates of fluvial and delta-terrace deposits of the Kızılırmak River, Black Sea coast, Turkey

Abstract

We analysed the interplay between coastal uplift, sea level change in the Black Sea, and incision of the Kızılırmak River in northern Turkey. These processes have created multiple co-genetic fluvial and marine terrace sequences that serve as excellent strain markers to assess the ongoing evolution of the Pontide orogenic wedge and the growth of the northern margin of the Central Anatolian Plateau. We used high-resolution topographic data, OSL ages, and published information on past sea levels to analyse the spatiotemporal evolution of these terraces; we derived a regional uplift model for the northward-advancing orogenic wedge that supports the notion of laterally variable uplift rates along the flanks of the Pontides. The best-fit uplift model defines a constant long-term uplift rate of 0.28 ± 0.07 m/ka for the last 545 ka. This model explains the evolution of the terrace sequence in light of active tectonic processes and superposed cycles of climate-controlled sea-level change. Our new data reveal regional uplift characteristics that are comparable to the inner sectors of the Central Pontides; accordingly, the rate of uplift diminishes with increasing distance from the main strand of the restraining bend of the North Anatolian Fault Zone (NAFZ). This spatial relationship between the regional impact of the restraining bend of the NAFZ and uplift of the Pontide wedge thus suggests a strong link between the activity of the NAFZ, deformation and uplift in the Pontide orogenic wedge, and the sustained lateral growth of the Central Anatolian Plateau flank.