HR: 1340h
AN: PP43A-0620    [Abstracts]
TI: Resumed Activity of the Dead Sea Ca-Cl Brine and the Northward Migration of the Levant Rain System Upon the MIS5/4 Transition
AU: * Waldmann, N
EM: nicolas.waldmann@terre.unige.ch
AF: Institute of Earth Sciences, The Hebrew University, Givat Ram, Jerusalem, 91904 Israel
AU: Starinsky, A
EM: stari@vms.huji.ac.il
AF: Institute of Earth Sciences, The Hebrew University, Givat Ram, Jerusalem, 91904 Israel
AU: Stein, M
EM: motis@vms.huji.ac.il
AF: Geological Survey of Israel, 30 Malkhe Yisrael St., Jerusalem, 95501 Israel
AB: Terminal lakes in the arid and semi-arid region of the Dead Sea basin expanded significantly or contracted and dried up depending on the way the hydrological system is reacting to the regional and global climate during the late Pleistocene-Holocene periods. We reconstructed the precipitation and hydrological history of the drainage area of the Dead Sea basin during the transition from the last Interglacial (MIS5) to the last Glacial period (MIS4). Thus, the lakes are considered as a large rain gauges and faithful monitors of the regional hydrological-climate system. Our assessment is based on lithological, mineralogical, isotopic and chemical evidence stored in the sedimentary-limnological record of Samra (Amora) and Lisan lakes that filled the Dead Sea basin during the late Pleistocene. Deposition of CaCO3 as authigenic aragonite or calcite from the lakes depends on the relative contribution of the ancient Dead Sea Ca-Cl brine to the lake waters. During the uppermost Pleistocene time (approximately 120-80 ka) mainly authigenic calcite was deposited in the lake suggesting minor contribution of the Ca-Cl brine relative to the freshwater input. The transition from the last Interglacial to last Glacial periods (the MIS5/4 transition at approximately 70 ka) was marked by resumed activity of freshwater springs in the vicinity of the Dead Sea (depositing travertines) and enhanced activity of the Ca-Cl brines, leading to precipitation of salt and authigenic aragonite. The MIS5/4 freshwater-brine change was associated with a regional migration of rainstorms to the north of the Negev desert. Since then, during the past 70 ka rainstorms were mostly limited to the drainage area of the Jordan River and Dead Sea shoulders.
DE: 4808 Chemical tracers
DE: 3344 Paleoclimatology
DE: 1800 HYDROLOGY
DE: 1845 Limnology
DE: 1615 Biogeochemical processes (4805)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting