Quaternary rise of the Sedom Diapir, Dead Sea basin
Quaternary rise of the Sedom Diapir, Dead Sea basin (in New frontiers in Dead Sea paleoenvironmental research, Yehouda Enzel (editor), Amotz Agnon (editor) and Mordechai Stein (editor))
Special Paper - Geological Society of America (2006) 401: 33-51
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 approximately 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 delta (super 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 approximately 5 mm/yr over the past 14,000 yr. Similar uplift rates of 6-9 mm/yr are inferred for "salt mirror" and hanging passages of caves. The present uplift rate, calculated from precise leveling an 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.
