Late-Holocene landscape evolution of a delta from the foredune ridges: Seyhan Delta, the Eastern Mediterranean, Turkey

The Çukurova Delta Complex, formed by the Seyhan, Ceyhan, and Berdan rivers, is the second-largest delta system in the Mediterranean. The delta complex is a major depocenter that contains sediments transported from the Taurus Mountain belt since the Miocene. Studies on the Quaternary landscape evolution of the Çukurova Delta Complex are scarce, and in particular, the Holocene evolution of the Seyhan Delta section of the Çukurova Delta Complex has been poorly understood. Sedimentological analysis, high-resolution digital elevation models derived using structure from motion, and optically stimulated luminescence dating of the foredune ridges in the Seyhan Delta help define the lesser-known nature of Late-Holocene paleoenvironmental and landscape evolution of the Seyhan section of the Çukurova Delta Complex. The foredune ridges provide evidence that the Akyatan Lagoon, one of Turkey’s largest lagoon, formed at the beginning of the last millennium. The ridges bordering the north and south of Tuzla Lagoon show that the lagoon completed its formation between the 11th and 14th centuries when the ancient delta was to the east. The Seyhan River flowed 10 km east from its current course until at least the 16th Century, and its ancient delta was active until that time. After the 16th Century, the Seyhan River shifted to its current course in the west and began to build the modern delta and the youngest foredune ridges were formed by a combination of aeolian and littoral processes. The contemporary delta continued to prograde until the construction of the Seyhan Dam in AD 1956. Since the construction of the Seyhan Dam, the delta shoreline at the river mouth retreated drastically and foredune formation stopped. In the past few decades, most of the foredune ridges have been eroded away by coastal processes and agricultural activities.

Thermoluminescence and dosimetric characteristics study of quartz samples from Seyhan Dam Lake Terraces

In the present study, soil samples of Seyhan Dam Lake Terraces were collected and then pure quartz samples were separated using various separation methods. The quartz samples were characterized using X-ray diffraction (XRD) and scanning electron microscopy – energy dispersive X-ray spectroscopy (SEM-EDX) methods. Thermoluminescence (TL) measurements were carried out using lexsyg smart TL – optically stimulated luminescence (OSL) reader with a constant heating rate of 1 °C/s from room temperature to 450 °C. Beta dose response of the samples were investigated in the dose range from 1 to 10 Gy and the linear dose response range was determined as 1–5 Gy. Computerized glow curve deconvolution (CGCD), peak shape, and isothermal decay (ID) methods were used to determine activation energy (E), order of kinetics (b), and frequency factor (s) of the samples. Furthermore, in this study, minimum detectable dose values of the quartz samples were also determined.