Tectonic, topographic and rock-type influences on large landslides at the northern margin of the Anatolian Plateau

Abstract

High Anatolian orographic margins have large variations in terms of topographic relief, precipitation, and uplift rate. These variations lead to the dynamics of mass movements and surface runoff, which are the dominant geomorphological processes in ice-free mountain landscapes. There is growing recognition that large landslides are important agents of landscape evolution, resulting in massive slope failures, which can cause extensive and rapid topographic changes in many active orogenic belts. Unlike the cognatic orogenic plateau margins in the world, there are no studies available on the large landslides and their geomorphic impact at the margins of the Anatolian Plateau. This study presents results from a regional-scale inventory of 1290 large landslides (> 1 km 2 ) that allow the characterization of spatial distribution and landslide-dominated landscapes in the northern margins of the Anatolian Plateau. The majority of large landslides are clustered in three main zones that correspond to the Western, Central, and Eastern Pontides, which is an east-west-trending orogenic belt that represents a coalesced tectonic entity in the northern section of Turkey. Nearly 80% of large landslides have occurred in a terrain with a mean hillslope relief of > 1000 m in those three landslide-dominated landscapes. The results of regional comparisons reveal that in addition to hillslope relief and steepness, lithotectonic differences largely control the abundance of landslides along the northern margins of the Anatolian Plateau. In this respect, the spatial distribution and abundance of large landslides imply a landscape in which lithological and tectonic controls on hillslope erosion are more significant than climate. The study further shows that the parallel or perpendicular position of the landslides with respect to the direction of the drainage network is effective as positive or negative feedback in response to fluvial dissection of the plateau margins. On the other hand, there is certainly a need for more comprehensive radiometric dating studies to understand the contribution of large landslides on the erosional decay rate of Anatolian Plateau margins. Furthermore, the presence of these large landslides and the derived deposits in this dynamic terrain provide a unique opportunity for deciphering the past climatic and seismic events.