Influence of seawater exchanges across the Bab-el-Mandeb Strait on sedimentation in the Southern Red Sea during the last 60ka

The location of core MD92-1008 close to the southern edge of the Red Sea is ideal to study the evolution of seawater exchanges with the Northern Indian Ocean through the Bab-el-Mandeb narrow strait. The present study was aimed at documenting the paleoceanographic evolution of this area over the past...

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Bibliographic Details
Published in:Paleoceanography 2013-12, Vol.28 (4), p.675-687
Main Authors: Bouilloux, Alexandra, Valet, Jean-Pierre, Bassinot, Franck, Joron, Jean-Louis, Dewilde, Fabien, Blanc-Valleron, Marie-Madeleine, Moreno, Eva
Format: Article
Language:English
Subjects:
Chemical analysis
Climate change
Continental margins
Deglaciation
Marine
Nutrients
Oceanography
Organic carbon
Organic matter
Paleoclimate science
Sea level rise
Seawater
Sedimentation & deposition
Straits
Water analysis
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Summary:The location of core MD92-1008 close to the southern edge of the Red Sea is ideal to study the evolution of seawater exchanges with the Northern Indian Ocean through the Bab-el-Mandeb narrow strait. The present study was aimed at documenting the paleoceanographic evolution of this area over the past 60ka using high-resolution magnetic, sedimentological, and geochemical indicators. Two modes of variability dominate the records: (i) long-term, glacial-interglacial variations and (ii) rapid, millennial scale variability (Dansgaard-Oeschger type) during the last glacial period. Changes in magnetic concentration were documented from natural and laboratory magnetizations after proper normalization. They are inversely correlated to the total organic carbon (TOC) content, pointing out the key role played by reductive dissolution of magnetite on the evolution of magnetic concentration. Based on the temporal evolution of TOC, CaCO3, and planktonic [delta]13C, we suggest that past changes in the organic matter content (i) were closely linked to glacio-eustatic variations which modulated long-term seawater exchanges and nutrient supplies to the Red Sea through the narrow Bab-el-Mandeb Strait and (ii) reflect millennial-scale changes in productivity driven by monsoon wind intensity which controlled the amount of nutrient-rich intermediate waters upwelled in the Gulf of Aden during the summer season and advected into the Southern Red Sea. The sea level rise following the onset of deglaciation generated a rapid flush of detrital material that was accumulated on the continental margins and on the previously emerged zones of the Bab-el-Mandeb area. Key Points Magnetic records document the Dansgaard-Oeschger events in this area Changes in the organic matter reflect millennial-scale changes in productivity Sudden flush of material at the onset of deglaciation
ISSN:2572-4517
0883-8305
2572-4525
1944-9186
DOI:10.1002/2013PA002544