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AGU: Paleoceanography

 

Keywords

  • millennial-scale climate variability
  • West Africa
  • Senegal
  • Intertropical Convergence Zone
  • environmental magnetism
  • color reflectance

Index Terms

  • Geochemistry: Marine geochemistry (4835, 4845, 4850)
  • Geomagnetism and Paleomagnetism: Environmental magnetism
  • Global Change: Abrupt/rapid climate change (4901, 8408)
  • Global Change: Climate variability (1635, 3305, 3309, 4215, 4513)
  • Atmospheric Processes: Paleoclimatology (0473, 4900)

Abstract

PALEOCEANOGRAPHY, VOL. 24, PA1205, 16 PP., 2009
doi:10.1029/2007PA001570

Millennial-scale northwest African droughts related to Heinrich events and Dansgaard-Oeschger cycles: Evidence in marine sediments from offshore Senegal

A. C. Itambi

Geosciences Department, University of Bremen, Bremen, Germany

T. von Dobeneck

Geosciences Department, University of Bremen, Bremen, Germany

Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany

S. Mulitza

Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany

T. Bickert

Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany

D. Heslop

Geosciences Department, University of Bremen, Bremen, Germany

Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany

We present a suite of new high-resolution records (0–135 ka) representing pulses of aeolian, fluvial, and biogenic sedimentation along the Senegalese continental margin. A multiproxy approach based on rock magnetic, element, and color data was applied on three cores enclosing the present-day northern limit of the ITCZ. A strong episodic aeolian contribution driven by stronger winds and dry conditions and characterized by high hematite and goethite input was revealed north of 13°N. These millennial-scale dust fluxes are synchronous with North Atlantic Heinrich stadials. Fluvial clay input driven by the West African monsoon predominates at 12°N and varies at Dansgaard-Oeschger time scales while marine productivity is strongly enhanced during the African humid periods and marine isotope stage 5. From latitudinal signal variations, we deduce that the last glacial ITCZ summer position was located between core positions at 12°26′ and 13°40′N. Furthermore, this work also shows that submillennial periods of aridity over northwest Africa occurred more frequently and farther south than previously thought.

Received 14 November 2007; accepted 24 October 2008; published 6 February 2009.

Citation: Itambi, A. C., T. von Dobeneck, S. Mulitza, T. Bickert, and D. Heslop (2009), Millennial-scale northwest African droughts related to Heinrich events and Dansgaard-Oeschger cycles: Evidence in marine sediments from offshore Senegal, Paleoceanography, 24, PA1205, doi:10.1029/2007PA001570.

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