Neogene drainage evolution of SW Anatolia (Türkiye): Integration of morphotectonics, drainage and denudation analyses

Abstract

This study integrates denudation analysis with morphotectonic characteristics, facies associations and drainage analysis to investigate the landscape evolution of SW Anatolia. Age-Elevation Relationship (AER) plots of published thermochronological data from drainage divides, valleys and preserved paleo-geomorphological landscape remnants provide insight into the region's drainage evolution. Cooling and denudation events identify the timing of divide formation, windgap formation and divide breaching, which leads to watergap formation.

We have subdivided SW Anatolia into distinct morphotectonic domains. Among these, the Gediz and Büyük Menderes faults and the Selimiye Shear Zone fragmented the Menderes Metamorphic Core Complex into three each of which experienced different cooling histories based on denudation analysis utilizing various low-temperature thermochronometers.

Hypsometric integral and channel profile analyses demonstrate significant variation in landscape maturity and drainage basin modifications over time. These analyses, combined with the interpretation and mapping of windgaps, watergaps and stream deflections, as well as the depositional environments of sediments and volcanic sequences, enable the reconstruction of drainage patterns from the early Miocene to Recent.

During the middle Miocene, the Sakarya drainage basin dominated central and eastern SW Anatolia, with the Gediz drainage basin being a minor part of the Küçük Menderes basin. The Büyük Menderes drainage basin, in contrast, drained the southern portion of SW Anatolia, while the Bakırçay catchment extended into the northern Gediz basin. By the late Miocene, the Sakarya drainage basin had lost a significant portion of its hinterland to the Gediz basin and several newly isolated basins, while also capturing the Burdur and Beyşehir basins, along with the mid- and upstream sections of the Büyük Menderes basin, thereby reducing its area by two-thirds. In the Pliocene, the Gediz drainage basin contracted by approximately 80%, while the Büyük Menderes basin expanded to absorb the Gediz and Tavas basins. During the Quaternary, the Büyük Menderes basin further shrank by around 60% as isolated basins formed in the east. Recent tectonic activity has led to the Gediz basin recapturing parts of its upstream area, while the Büyük Menderes basin regained previously isolated sections of the Gediz basin. The Dalaman and Eşençay basins also captured upstream isolated basins, while the Burdur basin was captured by the Aksu River, isolating the Beyşehir basin from Burdur.

These episodes of drainage reorganization are driven by dynamic topography, influenced by slab-edge processes and intensified by the westward escape of the Anatolian Block. The westward motion, combined with slab-tear-driven vertical movements, has led to substantial reconfiguration of the drainage networks in SW Anatolia over time.