Siliceous sedimentary record of the last 280 kyr in the Canary basin (NW Africa)

Siliceous microfossils were quantified in four sedimentary sequences off Northwest Africa in order to disclose the productivity story of the last 280 kyr. Three sediment cores retrieved along an E–W profile, at about 29°N (GeoB4240, GeoB4241 and GeoB4242), and one core (GeoB4216) from the highly productive area off Cape Ghir in the Canary Island region. At 29°N, along all but the most offshore sequences (GeoB4242), coincidence of high diatom accumulation rates (DAR) and high abundances of Chaetoceros spores, the upwelling-related species, indicate glacial stages (isotope stages (IS) 4 and 2) as more productive than the interglacial intervals (IS5 and Holocene). The DAR in the coastal area of the Canary basin during IS2 is of the same order of magnitude (108 valves cm−2 kyr−1) reported for Cape Blanc and one order of magnitude higher than reported for the Iberian margin. The deviation observed between the offshore (higher DAR at IS3 and 6) and the coastal diatom records (higher DAR at IS2 and 4) may be a reflection of local productivity generated by wind input of nutrients and advection from coastal sources. The occurrence of DAR spikes at the timing of some Heinrich events seems to support the hypothesis of productivity maxima associated with the presence of meltwater off NW Africa, as previously proposed by other authors.