The evolution of Barahta rhomb-shaped graben, Mount Hermon, Dead Sea transform

Abstract

Mount Hermon forms part of a NE-trending anticlinal structure formed during compression resulting from sinistral movement along the Dead Sea Rift Transform. At the northern end of the Hula Valley the Dead Sea Transform branches into five faults, one of which, the Rachaya Fault, crosses the Hermon on its western side, with about 1000 m of left-lateral displacement. The Rachaya Fault comprises two left-stepping segments: the southern Si' on Fault and the northern Shab'a Fault. As a result of this stepping, a rhomb-shaped graben was formed. Two of the bordering faults of the Barahta Valley are dip-slip faults (the northern and the western), whereas the other two are strike-slip faults. Kinematic calculations reveal that horizontal displacement of about 800 m was transferred from the Si' on Fault to the Shab'a Fault mainly along the eastern diagonal faults. The formation of the Barahta rhomb-shaped graben resulted from a local stress field formed due to the fault configuration and the motion of the Arabian block and not due to the regional stress field. The structure of the Barahta Graben can be largely explained by the rotational model rather than by the classic pull-apart model. It is concluded that stepover of strike-slip faults is essential for development of rhomb grabens but the mode of formation is different in each case and depends on the fault configuration and direction of block motion.