AN UPLIFTING IDEA: ESR DATING MARINE TERRACES IN HATAY PROVINCE, TURKEY

In the Mediterranean, subduction of the Mediterranean beneath the Anatolian Plate and two active transform faults, the Dead Sea and the Eastern Anatolian faults, mark the edges of main tectonic plates. Activity along these two faults and the Antakya-Samandağ fault connecting the Dead Sea fault to the Cyprus subduction system has destroyed ancient Antioch (now Antakya) and devastated all of Hatay Province several times. The Antakya-Samandağ Fault created significant vertical displacement and has uplifted the southeastern side of the fault relative to the northwestern side, producing a large fault scarp that parallels the Asi (Orontes) River and stranded some marine terraces high above current sealevel. To the northwest near Çevlik and Mağaracık, at least four Quaternary terraces can be recognized, while near Meydan and Tekebaşı three terraces are clearly visible. To understand the regional tectonic history, molluscs were collected from the marine terraces at 16 locations and were dated by standard ESR, which can date molluscs between 0.5 ka and 2 Ma. Ages were calculated using time-averaged and volumetrically averaged external dose rates. Cosmic dose rates were modelled assuming typical water depths for the individual species. Near Mağaracık, the 25 m to 105 m terraces yielded preliminary dates of 94 ± 10 to 241 ± 31 ka, which correlate with OIS 5 and 7, but postdate the 170 m terrace in Tekebaşı, which gave a preliminary age of 374 ± 56 ka, correlating with OIS 11. Therefore, the tectonic uplift appears to have averaged ~0.2-0.5 m/ky, across the area. That some shells within the terraces and paleosols have been reworked requires that more samples be dated to ensure accuracy. Estimating the cosmic dose rates remains the largest source of uncertainty in the ages, which will require better regional modelling for water depths and sediment cover thicknesses.