Neotectonic and topographic evolution of the Bitlis-Zagros Fold-Thrust Belt, SE Turkey

Abstract

: The Bitlis-Zagros Fold-Thrust Belt is one of the world’s largest deformation zones, extending from the Eastern Mediterranean in southern Turkey to in the south of Iran. This deformation zone is partitioned between different structures; however, little is known about the relative activities of these different structures and their effects on topography. An area located in the northern part of Bitlis-Zagros Fold-Thrust Belt, just south of the Eastern Anatolian Plateau was studied in detail to analyze the effect of active tectonism on topographic development. The effects of active deformation structures such as Hakkâri and Şirvan Fault Segments on the topographic evolution of Kato Folds and Sinebel Valley were investigated to understand the fold and thrust fault activity. Geomorphic indices were used, such as HC, HI, SR, Ksn together with rose analysis based on bedding measurements. Investigation of folding in the region indicates the effective stress regime in the precollision zone was in NW-SE compression direction. The deformation structures, effective in the postcollision zone developed due to N-S directional compression, and are shown here to have different effects on topography of the region. This study has shown the relative uplift rate is highest in the areas where Hakkâri and Şirvan Segments are pure thrust faults (0.4 mm year –1 ), and lower in the transfer zone (0.2 to 0.4 mm year –1 ) between the segments. As a result of this study, it is concluded that the main deformation structures controlling the topography in the region are not only thrust faults, but also structures that develop in the area of transfer zone.