Development of the Bet ha'Emeq structure and the tectonic activity of normal faults in the Galilee

A morphometric study of the Bet ha'Emeq drainage system. Upper Galilee, combined with available geological and structural data, enables the detection of tectonic stages that took place in the region, as well as a better understanding of the influence of tectonic activity on surficial processes. The preservation of Senonian and younger rock units in the downfaulted blocks of the Bet ha'Emeq Valley implies that normal faulting at rates compatible to denudation initiated during the Miocene and lasted ∼ 10 million years. During that time, ongoing truncation continued on the uplifted block, eliminating completely the Senonian units. The relation between the Bet ha'Emeq drainage system and adjacent structures implies that the relief of the Bet ha'Emeq Valley and the development of the drainage system in it preceded the development of the secondary uplifted blocks within the Bet ha'Emeq low structure, the neighboring Zurim Escarpment, and the formation of the regional tilt of the Upper Galilee. The present relation between the Zurim Escarpment and the Bet ha'Emeq drainage system suggests no observable retreat of the escarpment since its formation more than 4 Ma. Morphologic considerations and the existence of quartz geodes derived from the Cenomanian Deir Hana Formation on abandoned saddles along the present water divide of Nahal Bet ha'Emeq suggest that the headwaters of the Bet ha'Emeq drainage system used to be in the Beit Jann tectonic block. This block is currently disconnected from the Bet ha'Emeq drainage system due to normal displacement along the Sumi and Peqi'in faults. The present morphology of the Bet ha'Emeq Valley developed since the Pliocene. A fresh fault scarp in dolomite and knick points in Pleistocene travertine units in the western part of the Bet ha'Emeq Valley indicate late Pleistocene activity on the Bet ha'Emeq fault system. Incision of the Bet ha'Emeq drainage system as well as adjacent streams into alluvial terraces signals the response of the drainage system to the regional-scale uplift and is not associated with normal faulting of the Bet ha'Emeq system. The regional uplift is also expressed in the steep gradient of the Upper Galilee streams. The data collected in the Bet ha'Emeq and neighboring valleys indicate that faulting was active since the miocene and until the late Pleistocene, and that the development of the landscape is mainly controlled by rates of faulting and regional uplift, and less by surficial processes.