Yeşilırmak Havzası Yukarı Mecrasında Almus Fayı Boyunca Drenajın Gelişimi

Abstract

The Yeşilırmak River Basin is located in the North Anatolian Fault Zone (NAFZ) which is one of the fault zones with intense seismic activity in Turkey. The Almus Fault is a segment of the North Anatolian Fault (NAF). This study aims to reveal the effect of the Almus Fault on the drainage development and morphotectonic evolution of the upper catchment of the Yeşilırmak River Basin and the relative tectonic activity of the fault. Morphometric indices such as, stream length gradient index (SL), mountain front sinuosity (Smf) and fan entrenchment (E) indicate that the downward of the sub-basins is tectonically more active than the upward which is ascribed to the tectonic activities along the Almus Fault. The Smf value is 1.4 at the west and decreases to 1.1 at the mouth of the sub-basins on the east. This indicates that the tectonic activity along the Almus fault in the study area increases from west to east and the uplift rate in the northern part is higher than the southern part of the study area. Development of the drainage network started during Pliocene due to differential uplift and a humid climate then developed under tectonic forcing during Quaternary.