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. We are using this diapir as a natural laboratory to study salt rheology and tectonics.

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 ~2,400 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 years 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 ~40,000 years B.P. is inferred from Na/Ca ratios in aragonite and their relation to 13C. On the mountain itself, the older parts (70,000-43,000 years 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 bsl at about 14,000 years B.P. The present elevation of these sediments at 190 m bsl indicates an average uplift rate of ~5 mm/y over the last 14,000 years. Similar uplift rates of 6-9 mm/y 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.

We present a mechanical model for the growth of an emerging salt diapir in a tectonically active basin. The analytical model is applied to and serves to constrain the effective viscosity of rock salt and strain rates during diapirism of the wall-shaped Mount Sedom rock salt diapir, Dead Sea basin. The model is based on one-dimensional flow of Newtonian viscous fluid (salt) in a vertical channel that has been driven by the load of the overburden and affected by shear along the channel walls. Because the Poiseuille (channel) flow profile is parabolic and the Couette (shear) flow profile is linear, one-dimensional model provides three sets of predicted profiles; topography, uplift rate, and shear strain. The present topography of Mount Sedom represents the shape of the Sedom diapir, and, hence, the effective viscosity of rock salt can be constrained by a model that best fits the present topography of the mountain. The resulting Sedom rock salt viscosity is assured to be between 2-3x10^18 Pa s, and the associated strain rate is between 5-6x10^-13 1/s. Geological structures indicate strain rates of 9x10^-13 1/s and 3x10^-14 1/s during the Holocene emerging stage and at the Plio-Pleistocene pre-emergent stage of the Sedom diapir, respectively. The uplift history of Mount Sedom predicted by the model and the current topography are compared to Interferometric Synthetic Aperture Radar (InSAR) measurements of salt uplift. The maximum uplift rates of the Mount Sedom are 8.3 and 5.5 5 mm/y for its northern and southern parts, respectively. The InSAR uplift profiles resemble topographic profiles obtained along the same traverses, implying that the uplift history during the last 14,000 years is stable. Steep uplift gradients observed by InSAR along the western margin of the diapir are higher than predicted by modeling of Newtonian viscous flow. This could imply that flow of power-law viscous fluid may be more suitable than that of Newtonian viscous fluid for the Sedom rock salt at high strain rates above 8x10^-13 1/s.

In this study I am collaborating with Vladimir Lyakhovsky, Ze'ev B. Begin, and Gidi Baer