HR: 11:50h
AN: PP52B-07    [Abstracts]
TI: Paleoclimate of the Eastern Mediterranean/North Africa during the past 26 cal ka based on organic geochemical investigations of a Nile River Delta sediment core
AU: * Castaneda, I S
EM: castaneda@nioz.nl
AF: Royal Netherlands Institute for Sea Research (NIOZ), PO Box 59, Den Burg, Texel, 1790 AB, Netherlands
AU: Schefuss, E
EM: schefuss@uni-bremen.de
AF: DFG-Research Center Ocean Margins, University of Bremen P.O. Box 330440, Bremen, D-28334, Germany
AU: Patzold, J
EM: juergen.paetzold@uni-bremen.de
AF: DFG-Research Center Ocean Margins, University of Bremen P.O. Box 330440, Bremen, D-28334, Germany
AU: Sinninghe Damste, J S
EM: damste@nioz.nl
AF: Royal Netherlands Institute for Sea Research (NIOZ), PO Box 59, Den Burg, Texel, 1790 AB, Netherlands
AU: Schouten, S
EM: schouten@nioz.nl
AF: Royal Netherlands Institute for Sea Research (NIOZ), PO Box 59, Den Burg, Texel, 1790 AB, Netherlands
AB: The Mediterranean Sea is situated within a highly sensitive climatic region, which is influenced by both tropical and mid-latitude climate dynamics, and the paleoenvironmental history of this region is of interest because large human populations occupy the surrounding landmasses. In this study, multiple organic geochemical proxies are examined from a Nile River Delta sediment core (GeoB 7702-3) to investigate the paleoclimatic history of the North Africa/Eastern Mediterranean region during the past ~26 cal ka. Sea surface temperatures were reconstructed using both the TEX86 and alkenone paleothermometers. The TEX86 record exhibits centennial to millennial scale variability and captures global climate events including the Last Glacial Maximum (LGM), Heinrich Event 1 (H1), the Bolling/Allerod and the Younger Dryas (YD). The recently developed Branched and Isoprenoid Tetraether (BIT) index, used to differentiate between marine and terrestrial inputs, closely tracks changes noted in bulk C/N ratios. Overall, these records indicate greater variability during the Late Pleistocene than during the Holocene, with the highest terrestrial inputs noted at approximately the time of the YD and prior to H1. Although it might be expected that fluvial organic matter inputs should be the lowest during the LGM, when the sources of both the Blue and White Nile were severely reduced or desiccated, higher (more terrestrial) BIT values noted at these times may be related to changes in vegetation cover in North Africa. During the Holocene, a major shift in the BIT index to lower (more marine) values marks the onset of deposition of the S1 sapropel layer. The lower BIT values noted during this interval are caused by a dramatic (order of magnitude) increase in the absolute abundance of crenarchaeol, attesting to enhanced marine productivity at this time. Following deposition of the S1 sapropel, absolute abundances of crenarchaeol are generally higher than during the Late Pleistocene, suggesting increased marine productivity in the eastern Mediterranean throughout the Holocene.
DE: 1055 Organic and biogenic geochemistry
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1637 Regional climate change
DE: 4954 Sea surface temperature
DE: 9305 Africa
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting