Late Cenozoic and active transpression along the Dead Sea fault in northwestern Syria

The left-lateral Dead Sea fault (DSF) constitutes the boundary between the Arabian and African plates as they converge with Eurasia. In northwestern Syria, the DSF emerges from the 200-km-long "Lebanese" restraining bend with a single fault trace that bifurcates at the Ghab Valley. Despite locally transtensional features like the Ghab Valley, neotectonic activity along the northern DSF in northwestern Syria demonstrates that oblique plate motions result in an overall transpressive tectonic regime. Constraints on recent tectonism are provided by neotectonic mapping, trenching of Holocene sediments, and analyses of a 20-meter pixel digital elevation model constructed using InSAR. Evidence of Neogene and Quaternary displacement on the northern DSF includes truncation and offset of a large, early Pliocene volcano. Preliminary estimates of the left-lateral slip rate south of the Ghab Valley are 4 - 7 mm / yr. In the Ghab Valley, hanging valleys, beheaded drainages, and displaced late Quaternary lava flows demonstrate that plate motion is distributed among several active fault branches. Furthermore, warping and tilting of a late Miocene - early Pliocene paleo-surface, as well as morphometric analyses, suggest that tectonic uplift of the Syrian Coastal Range has been coincident with recent left-lateral faulting on the adjacent DSF. Uplift is asymmetrically distributed in that it is almost exclusively located in the western block of the DSF. The region of uplift is greatest adjacent to the Ghab Valley. This may reflect a contribution from isostatic uplift as a result of the local transtension. We suggest that a convergent component of plate motion is responsible for uplift of the entire Syrian Coastal Range. Our hypothesis is consistent with regional plate tectonic models that predict 10° - 25° obliquity between the Arabian-African plate motion and the strike of the northern Dead Sea fault.