Late Cenozoic tectonics and volcanism in the northwestern corner of the Arabian plate: a consequence of the strike-slip Dead Sea fault zone and the lateral escape of Anatolia

Abstract

The study area is the northwestern corner of the Arabian plate, near the triple junction of Anatolian, Arabia and Africa. Late Cenozoic tectonics and volcanism have developed essentially east of the Dead Sea fault zone (DSFZ), the strike-slip boundary of the Arabian and African plates, including vents situated in front of the Bitlis collisional belt. Isotopic and rare elements data indicate deep mantle sources for volcanism. Our mapping, based on radar imagery and digital elevation models, suggests that elongate volcanoes, volcanic ridges and linear clusters of adjacent volcanic vents are rooted on tension fractures, which are a kilometer or several kilometers in length, and infers similar development in depth. We have also observed non-volcanic tension fractures. We have been able to map the northern segment of the DSFZ as a continuous but broken fault line. The Ghab pull-apart basin connects with appended faults, including the Choukhour fault that ends northward in a tail-crack feature and the Aafrine fault that ends in a tail-thrust. The Amik pull-apart basin is bounded in the west by a small but distinct scarp shown by radar imagery. Our image analysis and field data suggest that the left-lateral Amanos fault has a reverse throw component. In consequence, the Amanos Range has to be regarded as an anticline and the Karasu valley as a syncline. In the southern part of the study area, the regional stress field is mainly strike-slip with N020°-striking tension fractures. East of the Amanos fault, it becomes transpressive with N120°- to N140°-striking tension fractures. In the north, near the triple junction, albeit compressional, faults and belt environment predominate, it is influenced by E–W lowering horizontal stress component, triggered by the lateral escape of Anatolia, and remains of the strike-slip type, associated with N020°-striking tension fractures. More east of the DSFZ, in front of the Bitlis belt, isolated volcanoes (e.g. Karacadag, elongated N160°) show, in the rigid Arabian crust, local weak lines that can be influenced at a distance by the lowering horizontal stress component.