Southward migration of rain tracks during the last glacial, revealed by salinity gradient in Lake Lisan (Dead Sea rift)

Abstract

The paleosalinity of the Late Pleistocene Lake Lisan during its highstand between ∼27,000 and 15,000 years B.P. is evaluated from biological data (diatoms, cyanobacteria, fish and ostracods) and chemical data (Sr/Ca and Na/Ca ratios) in authigenic aragonite. The data indicate a zone of maximum salinity at the southern part of the lake, in the vicinity of the present Dead Sea basin. While most of the freshwater input to Lake Lisan originated from the Jordan River in the north and runoff from the eastern and western parts of the drainage basin, our analysis indicates a significant additional contribution from a southern freshwater source. At present, the contribution of the southern source to the Dead Sea is minimal. Hence, it appears that in addition to the prevailing rain originating from the Mediterranean, an additional, southern source of rain, was more active during the Last Glacial than today. This may be explained by migration of rain tracks, whose moisture originated in the Atlantic, from the Mediterranean southwards.