Development of the Inland Sea and its evaporites in the Jordan-Dead Sea Transform based on hydrogeochemical considerations and the geological consequences

Differences in the distribution of Na/Cl, Br/Cl and Mg/Ca equivalent values suggest a morphotectonic barrier at Marma Feiyad dividing the Tertiary Inland Sea into two basins covering the region of the Jordan Valley, Middle East. Depending on the Tethys sea level, three phases of evaporation are distinguishable that are related to three sections of the drilling log of Zemah 1. In phase 1 and 3 only the northern basin was flooded. During phase 2 both basins were inundated, but halite mainly precipitated in the southern one. The halite deposition in one or the other basin by evaporation is estimated by applying a two-box model. The results are constrained by the average subduction rate of 700–875 m/Ma and characteristic Na/Cl values of 0.52 and 0.12 in the northern and southern basin, respectively. In different scenarios the sedimentation rates of halite and non-halite components are varied due to assumed halokinesis, reshuffling of salt and erosion of non-halite sediments. These simulations suggest that periods of 450–600 and 100–170 ka in the southern and northern basin were needed, until the Na/Cl values of 0.12 and 0.52 were, respectively, attained. The Inland Sea most probably existed for 2.2 ± 0.3 Ma between 8.5 and 6.3 Ma ago (Tortonian). It was terminated at the beginning of the Messinian crisis. In all simulations the drainage flux into the southern basin exceeded that into the northern basin, suggesting that the proto-Jordan River either did not exist at that time or did not discharge into the northern basin.