HR: 1340h
AN: PP43A-0662    [Abstracts]
TI: Holocene Clay Minerals in the Aegean Sea Record African and European Climate Variability
AU: * Ehrmann, W U
EM: ehrmann@rz.uni-leipzig.de
AF: Leipzig University, Institute of Geophysics and Geology, Talstrasse 35, Leipzig, 04103 Germany
AU: Hamann, Y
EM: yhamann@rz.uni-leipzig.de
AF: Leipzig University, Institute of Geophysics and Geology, Talstrasse 35, Leipzig, 04103 Germany
AU: Schmiedl, G H
EM: schmiedl@rz.uni-leipzig.de
AF: Leipzig University, Institute of Geophysics and Geology, Talstrasse 35, Leipzig, 04103 Germany
AU: Kuhnt, T
EM: tkuhnt@rz.uni-leipzig.de
AF: Leipzig University, Institute of Geophysics and Geology, Talstrasse 35, Leipzig, 04103 Germany
AB: The distribution of clay minerals has been studied in two deep-sea sediment cores from the North and South Aegean Sea spanning the time interval of the last glacial maximum to the present. The clay mineral assemblages reveal significantly different patterns in the comparison of the cores suggesting that the studied sites were influenced by different source areas, oceanography and climate regimes. For better evaluation of the late glacial and Holocene records we compiled data on the clay mineral composition in surface sediments of the Aegean Sea in order to decipher source areas and transport paths. The clay mineral assemblages in the near-coastal areas carry the signature of the riverine sediment discharge from southeastern Europe and Turkey. The suspension load of North Aegean rivers exhibits low Smectite/Illite (Sm/Ill) ratios. The South Aegean Sea is influenced by the Nile discharge and transport of clay minerals by surface currents. This assemblage shows high Sm/Ill ratios. In the North Aegean Sea, the post-glacial development of clay mineral assemblages is controlled by the sea-level rise, melting of Southeast European glaciers, and establishment of the connection between the Black Sea and Aegean Sea. The long-term development of clay mineral assemblages in the South Aegean Sea reflects changes in the Nile discharge. In the early Holocene, the onset of pluvial conditions of the Nile catchment is reflected by a drastic rise in Sm/Ill ratios. In addition, the clay mineral records exhibit periodic millennial-scale fluctuations. In the North Aegean Sea, regular changes in the Sm/Ill ratio are centered at a period of 1600 years. These changes are particularly expressed during the middle and late Holocene and show variable amplitudes. Around 4.5 and 1.5 kyr B.P., Sm/Ill ratios drop to minimum values indicating times of high river discharge and humidity in southeastern Europe. In contrast, the late glacial to Holocene Sm/Ill ratio of the South Aegean Sea is characterized by regular fluctuations centered at a period of 1000 years. This signal likely reflects short-term changes of the Nile discharge and intensity of East African monsoon rainfall.
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4926 Glacial
DE: 4936 Interglacial
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005