The morphotectonic depression of the Dead Sea Fault (DSF) is the deepest continental depression on Earth. Tectonic activity began in the early Miocene with strike-slip faulting, while significant vertical subsidence developed later, from the late Miocene onward. Current knowledge of basin formation and subsidence rates is mainly based on dating basalts, paleo-lake sediments, and fluvial deposits. These studies indicate the presence of rift lakes since the late Miocene but provide only limited constraints on subsidence rates of the basin.
This study aims to define the chronology of the Dead Sea basin subsidence and reconstruct regional paleo–groundwater levels linked to paleo–rift lakes, using U-series dating of speleothems from relict karstic aquifers at different elevations in the Judean Desert. These aquifers were abandoned due to groundwater-level decline associated with subsidence of the DSF. The study focused on phreatic speleothems, cave deposits that formed at or below groundwater, marking aquifer positions. Vadose speleothems that were formed later above the water table were also dated, recording aquifer retreat and transition to gravity-driven flow. Previous studies using the same method located Miocene groundwater and dated the onset of the DSF and the abandonment of a +500 m a.s.l. aquifer to ~6 Ma. This study builds on previous work and improves our understanding of the younger tectonic stages of the DSF.
Based on 74 ages, two paleo-groundwater levels were identified. The first, at a present-day elevation of 100–150 m above sea level, existed between 4.5±0.17 and 3.11±0.11 Ma. The second, at ~95–160 m below present sea level, was dated to between 815±150 ka and 164±1.35 ka.
These preliminary results constrain paleo-elevations of rift-lake levels recorded by groundwater and document their temporal evolution. The data indicate vertical tectonics with stable base levels separated by rapid Dead Sea basin subsidence, with a mean subsidence rate of 85 m/Ma.