RADIOCARBON RESERVOIR AGES IN THE HOLOCENE DEAD SEA

The sources and fate of radiocarbon (C-14) in the Dead Sea hypersaline solution are evaluated with C-14 measurements in organic debris and primary aragonite collected from exposures of the Holocene Ze'elim Formation. The reservoir age (RA) is defined as the difference between the radiocarbon age of the aragonite at time of its precipitation (representing lake's dissolved inorganic carbon pig) and the age of contemporaneous organic debris (representing atmospheric radiocarbon). Evaluation of the data for the past 6000 yr from Dead Sea sediments reveal that the lake's RA decreased from 2890 yr at 6 cal kyr BP to 2300 yr at present. The RA lies at similar to 2400 yr during the past 3000 yr, when the lake was characterized by continuous deposition of primary aragonite, which implies a continuous supply of freshwater-bicarbonate into the lake. This process reflects the overall stability of the hydrological-climate conditions in the lake's watershed during the late Holocene where bicarbonate originated from dissolution of the surface cover in the watershed that was transported to the Dead Sea by the freshwater runoff. An excellent correlation (R-2=0.98) exists between aragonite ages and contemporaneous organic debris, allowing the estimation of ages of various primary deposits where organic debris are not available.