Storminess control over African dust input to the Moroccan Atlantic margin (NW Africa) at the time of maxima boreal summer insolation: a record of the last 220 kyr

Precessional forcing of dust flux from Northwest Africa to the Atlantic during the last 220 kyr is recognised through changes in physical and chemical sediment properties (sediment colour reflectance, magnetic susceptibility, Xray fluorescence element intensity) in a core from the Moroccan margin. Sediment colour reflectance, magnetic susceptibility, and Ca and Fe element intensity changes are thought to be driven by dust input from North Africa. Spectral analysis of the sediment properties records displays a dominant periodicity in the 1/23 kyr(-1) frequency band that is associated with the Earth's orbital precession. Peaks in terrigenous supply match precessional minima. This suggests a close link between maxima of boreal summer solar radiation, monsoon activity, and dust generation. Enhanced precession-driven solar radiation would have caused increased seasonal temperature contrasts, which amplified atmospheric turbulence and stimulated storminess. Such a scenario is similar to today's summer conditions, when frequent storms cause distinct dust plumes to form in the area and transport fine terrigenous material to the adjacent North Atlantic Ocean. (C) 2002 Elsevier Science B.V. All rights reserved.