干旱区生态环境知识资源中心

New oxygen isotope data and a high-resolution carbonate record of a core from the northwest African margin are presented, in combination with geochemical (Zr/Rb ratio, Al, Pa, organic carbon, and biogenic opal fluxes) and sedimentological (median grain size) parameters, to show variations in African continental aridity, wind strength, and upwelling productivity. The carbonate record is diluted by the supply of aeolian dust from the arid Saharan region of north Africa and is seen to vary with a characteristic sawtooth pattern indicating rapid increases in dust flux followed by gradual declines. Spectral analysis of the carbonate profile and comparison with SPECMAP (stacked oxygen isotope) and ETP (solar radiation) profiles shows that the precessional (23 kyr) insolation-induced African climate system is decoupled from global (ice volume) climate changes operating on a 100 kyr frequency. Detailed studies of glacial terminations I, II, and III confirm the presence of rapid, short timescale climatic variations (in aridity).