The Significance and Morphotectonic Features of the Iğdır Fault Within the Eastern Anatolian Compressional Tectonic Block

Abstract

The Iğdır Fault Zone (IFZ) is located at the easternmost edge of Turkey, approximately 13 km northwest of Mount Ağrı. The fault extends from Küllük village in the northwest to Kavaktepe village in the southeast. The right-lateral strike-slip Iğdır Fault Zone, which exhibits strike variations between N20 degrees E and N60 degrees E, consists of 19 sub-geometric segments. Fault-controlled drainage networks, offset streams, alluvial and colluvial fans, and truncated valleys are key morphological indicators of the faults' activity. This study aims to determine the tectonic influence of the Iğdır Fault Zone, which is situated within the Small Caucasus Tectonic Block. To achieve this objective, both historical and instrumental earthquake catalogs were compiled for the IFZ and its vicinity. Additionally, morphometric analyses were conducted on the fault zone, including surface roughness, hypsometric integral, basin asymmetry factor, mountain front sinuosity, and the ratio of valley floor width to valley height. The identified morphotectonic markers and index results indicate that the IFZ also possesses a normal fault component. The fault zone consists of five parallel sub-branches and exhibits a releasing bend structure, merging with the Mount Ağrı extensional crack in the southeastern section. The historical seismicity and morphometric index results suggest that the study area is morphologically young, with an uplift rate exceeding 0.5 mm per year in the NW and SE sections. When the fault length and index results are evaluated, it is observed that the southeastern segments of the Iğdır Fault Zone, particularly those closer to Mount Ağrı, have accumulated relatively higher deformation and exhibit a greater uplift rate.