Active Collision Zones: Morphotectonic Analysis, Cosmogenic Nuclide Evidence and Kinematic Modelling of the Turkish-Iranian Plateau and Caucasus Regions

Abstract

The main motivation and goal of this study is to investigate landscape evolution and ongoing crustal deformation in active collisional zones. To do so, this study concentrates on the Turkish-Iranian Plateau and Caucasus because it is a region of ongoing deformation and active seismicity that is situated between the Arabian and Eurasian plates. This region is complex due to different tectonic processes including post-collisional volcanism and active faulting. Quantitative information on uplift, incision and erosion from surface features can address landscape evolution such as where and how the high relief was developed and whether relief is in transient or steady state. In addition, exploring the location of maximum strain accumulation indicates how deformation is accommodated in the crust. To identify the indicators and signals of tectonic activity and their relationship with catchment-average erosion rates and to estimate strain rate and active long-term deformation with spatial-temporal distribution, this study applies a combination of quantitative topographic analysis based on digital elevation model data, catchment-averaged erosion rates measured from 10Be concentrations in river sands, and using kinematic modelling across the western part of Turkish-Iranian Plateau and south Caucasus Region. The first part of this thesis consist of quantitative morphometric/topographic analysis and indicates that the drainage networks of the “Qezel-Owzan and Kura-Arax” rivers in the study area are not in an equilibrium state. This is specifically documented in the lower catchment of Qezel-Owzan River and upper catchment of Kura-Arax Rivers. The disequilibrium is associated with drainage divide reorganization and captures, which display the ongoing dynamics and migration of the river basin drainage divides towards the internal plateau. The second part of this thesis consists of quantification of short-term landscape erosion rates derived from river sand 10Be content across three distinct tectono-stratigraphic zones from the upper to lower catchments of the Qezel-Owzan River in the north Iranian Plateau and west Alborz Mountain Range. The lower catchment has higher erosion rates/higher topographic metrics and annual precipitation compared to the upper/middle catchments in the plateau. This suggests that a different state exists between the lower and upper/middle parts of the catchment. Comparison between long-term exhumation rates (AFT/He data) and short-term erosion rates in the lower catchment suggest that the region has experienced a steady erosion rate since ~5 Ma, indicating a stability between erosion rate and regional shortening. The final part of this thesis presents the results of kinematic modelling in the frame of estimated long-term slip rates of the active faults and strain rates. The best fit of the kinematic model, with geodetic, geologic data and stress direction inputs, displays that crustal deformation is mostly accommodated by the active fault systems. Active faulting is primarily accommodated by right-lateral strike slip faults in the western part of Turkish-Iranian Plateau and Lesser Caucasus, but a high degree of shortening associated with the deformation is partly due to active thrust faults within the Talesh and Bitlis regions, with supplementary shortening in the Alborz and Greater Caucasus fold and thrust systems.