HR: 1340h
AN: PP23B-1419    [Abstracts]
TI: A Continuous High-Resolution Climate-Proxy Record of the past 2600 Years from the Central Sahara Desert
AU: * Verschuren, D
EM: dirk.verschuren@UGent.be
AF: Limnology, Department of Biology, Ghent University, Ledeganckstraat 35, Gent, B-9000 Belgium
AU: Schuster, M
AF: SFB389, Heinrich-Barth-Institut, Universitaet zu Koeln, Jennerstrasse 8, Koeln, D-50823 Germany
AU: Cocquyt, C
AF: PAE, Department of Biology, Ghent University, Krijgslaan 281-S8, Gent, B-9000 Belgium
AU: Russell, J M
AF: Limnological Research Center, University of Minnesota, 220 Pills H, 310 Pillsbury Dr SE, Minneapolis, MN 55455 United States
AU: Engstrom, D R
AF: St.Croix Watershed Research Station, Science Museum of Minnesota, Marine on St.Croix, MN 55047 United States
AU: Kroepelin, S
EM: s.kroe@uni-koeln.de
AF: SFB389, Heinrich-Barth-Institut, Universitaet zu Koeln, Jennerstrasse 8, Koeln, D-50823 Germany
AB: Persistent lack of high-quality climate-proxy records from the arid-subarid belt of North Africa has hampered analysis of decade-to-century-scale climate tele-connections between warm-temperate southern Europe and the monsoonal climate regimes of sub-Saharan tropical Africa. Here we report recovery of a finely laminated sediment record from Lake Yoa, a stratified hypersaline lake occupying a Pleistocene deflation basin at Ounianga Kebir in northeastern Chad (20.0øN; 20.5øE). It represents a continuous, annual-resolution record of climate and environmental change during the past 2600 $^{14}$C years from the hyper-arid core of the Sahara desert where rainfall is erratic and annual evaporation exceeds 600 cm. Lake Yoa is one of the very few permanent waters in this region maintained today by sub-surface inflow of fossil groundwater from sandstone aquifers recharged during the early-Holocene humid period. Preliminary sedimentological, chronological and fossil-diatom data suggest that Lake Yoa has been poly- to hyper-saline throughout the sampled period, and with conditions of physical and chemical limnology similar to those prevailing today for at least the past 1000 years. Given that the desert landscape in a large area surrounding Ounianga probably lacked significant ground cover throughout this period, we surmise that variation in aeolian mineral sediment input to the lake, partly reflected in distinct sand layers, could be exploited as a proxy of past changes in the intensity of dry northeasterly trade winds over central North Africa.
DE: 9305 Africa
DE: 3344 Paleoclimatology
DE: 3374 Tropical meteorology
DE: 3309 Climatology (1620)
DE: 1620 Climate dynamics (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting