Vertical Deformation Along a Strike-Slip Plate Boundary: The Uplifted Marine Terraces of the Gulf of Aqaba and Tiran Island, at the Southern End of the Dead Sea Fault

Abstract

Close to its southern end where it connects to the Red Sea rift, the Dead Sea strike-slip fault (DSF) becomes trans-tensional in the Gulf of Aqaba. Details of this transition, however, remain difficult to unravel as most of the active tectonic structures are located off-shore. This study focuses on uplifted marine terraces located in the Gulf of Aqaba and on Tiran Island. Using high-resolution tri-stereo Pleiades satellite imagery, we build a Digital Surface Model (DSM) at a 0.5-m resolution of the eastern coast of the gulf and Tiran Island to map 19 levels of marine terraces. The terraces are preserved at elevations from 1 m to almost 500 m above the current sea level. Correlating laterally U-Th ages obtained along the gulf with the lower levels found on Tiran Island, we build an age model to estimate the ages of the upper terraces on the island. Combining this with the terrace heights from our DSM, we derive the uplift rate affecting the terraces. The geographic extent of the terraces along the gulf suggests that the DSF is responsible for uplift along the entire eastern coastline of the gulf at a rate of about 0.14 ± 0.03 mm/year at least over the Quaternary. The uplift rate of Tiran Island, located closer to the Red Sea rift, is faster at 0.21 ± 0.02 mm/year over the past 2.4 Myr. This faster uplift rate suggests a combined tectonic uplift related to both the Dead Sea strike-slip fault system and the Red Sea rift.