Mount Sedom is the surface expression of a salt diapir that has emerged since the Pleistocene in the southwestern part of the Dead Sea basin. Milestones in the uplift history of the Sedom salt diapir since its inception were deduced from angular and erosional unconformities, thickness variations, caprock formation, chemistry and isotope composition of lacustrine aragonite, cave morphology, precise leveling, and satellite geodesy. Thickness variations of the overburden observed in transverse seismic lines suggest that significant growth of the Sedom diapir may have initiated only after this thickness exceeded ∼2400 m in the Late Pliocene. The formation of the caprock signifies the arrival of the Sedom diapir from depth to the dissolution level between 300,000–100,000 yr B.P. During this period and later, angular and erosional unconformities in the upper part of the overburden near Mount Sedom are attributed to the piercing diapir. Rapid solution of rock salt from parts of Mount Sedom inundated by Lake Lisan after ca. 40,000 yr B.P. is inferred from Na/Ca ratios in aragonite and their relation to δ 13 C. On the mountain itself, the older parts (70,000–43,000 yr B.P.) of the lacustrine Lisan Formation are missing. The top of the preserved sediments is covered by alluvial sediments that must have been deposited when the elevation of Mount Sedom was not higher than 265 m below sea level (mbsl) at ca. 14,000 yr B.P. The present elevation of these sediments at 190 mbsl indicates an average uplift rate of ∼5 mm/yr over the past 14,000 yr. Similar uplift rates of 6–9 mm/yr are inferred for the Holocene from displacement of the “salt mirror” and hanging passages of caves. The present uplift rate, calculated from precise leveling and interferometric synthetic aperture radar (InSAR), is similar to the average Holocene rate. Based on the gathered data, we reconstruct the topographic rise of Sedom diapir and its relation to lake level variations during the late Pleistocene and Holocene.

The Dead Sea Depression is an ∼230-km-long and up to ∼10-km-deep structural-gravitational low along the southern Dead Sea Transform plate boundary between Africa and Arabia. Following an early Miocene–Pliocene deformation phase of localized strike slip faulting and intense fluvial deposition in confined pull-apart basins, delocalization of the Dead Sea Transform and formation of a shear zone over the entire current width of the Dead Sea Depression took place in late Pliocene–early Pleistocene time. Integration of relocated epicenters and focal mechanisms of M L 2.5 earthquakes with a range of structural and geophysical data shows that the late-phase asymmetrical shear zone consists of a distinct sinistral boundary fault in the east and a broad zone of distributed shear to the west. It is characterized by a penetrative, bimodal (NW and NE) structural orientation pattern reflected in earthquake focal mechanisms, segments of the western boundary fault system, fracture sets, geomorphic lineaments, and linear clusters of collapse sinkholes. These phenomena are a manifestation of a long-term persistent deformation field that involves at least the entire upper crust. The shear zone fault structure consists of normal-dextral, NE-oriented faults that extend northeastward from the western boundary fault and intervening NW-trending normal faults. These fault sets produce subsided, fault-bounded depocenters within the Dead Sea basin. The NE-oriented and axially extending blocks are expected to rotate in a clockwise sense with the relative sinistral plate motion, resulting in both normal-dextral and normal-sinistral slip events along the western boundary fault system. Since the Dead Sea Transform plate boundary is non-convergent and probably driven by sinistral basal flow, the Dead Sea Depression shear zone is internally contracting and subsiding. Partition of the relative plate motion between sinistral slip along the eastern boundary fault and distributed shear within the Dead Sea Depression may explain the apparent deficiency in seismic slip along the southern Dead Sea Transform relative to average long-term geological slip.

This paper summarizes the research efforts devoted over the years to the understanding of the origin and evolution of brines in the Dead Sea basin. These brines are characterized by a unique Ca-Chloride composition, which evolved from interaction of evaporated seawater filling the late Neogene Sedom lagoon with the Cretaceous carbonate rocks exposed at the basin-bounding escarpments. Following the disconnection of the lagoon from the open sea and the development of inland lakes, the composition of the ancient Sedom brine changed due to precipitation of evaporites and addition of salts from incoming fresh water. Relative to highly evaporated seawater, these processes led to enrichment of the brines in Cl, Br, Mg, Ca, and K and depletion in Na and SO 4 . The modern Dead Sea, representing a recent product of these evolutionary processes, derived its ingredients from residual brines that remained after the desiccation of the late Pleistocene Lake Lisan, from incoming fresh water, and from saline springs that emerge along the western shores of the Dead Sea. Similar sources probably dictated the composition of the Pleistocene lakes (Amora, Lisan), though their relative contribution changed through time, reflecting the control of climate on the hydrological system (e.g., the activity of saline springs).