Paleoceanographical Reconstructions of the Nile Deep-Sea Fan During Late Quaternary—Characterization and Evolution of Sedimentary Processes

Ducassou, Emmanuelle¹, Anne Murat², Sebastien Migeon³, Eliane Gonthier¹, Thierry Mulder¹, Jean Mascle³, Stefano Bernasconi⁴, Lucilla Capotondi⁵, Josette Duprat¹, Pierre Carbonel¹ (1) University Bordeaux 1, Talence Cedex, France (2) Cnam-Intechmer, 50103 Cherbourg Cedex, France (3) UMR Geosciences Azur, Villefranche sur Mer, 6 France (4) Geologisches Institut, Zuerich, Switzerland (5) Istituto per la Geologia Marina, Bologna, Italy

The Nile deep-sea fan is the largest sedimentary body of the Eastern Mediterranean and is subjected to a strong tectonic forcing (crustal and salt tectonics). During Quaternary, the Nile River experienced several changes of flow regime due to temporal climatic changes and to the fact that the drainage basin is located under various climatic settings. The flood regime varied especially in response to the monsoon variations. We try to decipher the impact of these changes in the deep submarine fan for the Quaternary.

The detailed study of 45 sediment cores allows to estimate this climatic forcing at high and low frequencies on pelagic and terrigeneous sedimentation.

To obtain the sedimentological and palaeoceanographical process reconstructions for the last 500,000 years, the lithological facies analysis and geochemistry have been support­ed by an accurate stratigraphy (tephrochronology, sapropels, biostratigraphy, stable and radiogenic isotopes).

The main observations show a wide range of sedimentary dispersal and depositional processes from west to east as typical turbiditic channel-levee complexes and terminal lobes, and their migration, giant sediment failures of the upper slope or deformed morpholo­gies due to the gravitational tectonics.

The Rosetta complex, in the western province, is the most recent turbiditic system. Its setting up, growth and migration seem to occur during the last glaciation (marine isotope stages 4, 3 and 2). On the contrary, the eastern province of the Nile deep-sea fan became inactive since the last interglacial period (MIS 5).