Millennial-scale variability in the productivity signal from the Alboran Sea record, Western Mediterranean Sea

Abstract

Primary productivity of the Alboran Sea (Western Mediterranean) is reconstructed for the time interval 48,000 to 28,000 years BP using the following geochemical proxies: calcium carbonate, barium excess (Baexcess), total organic carbon (TOC) and alkenone concentration. The records show a consistent pattern that indicates enhanced productivity during Dansgaard/Oeschger (D/O) warm periods. At the same time, deep-water conditions were favorable for organic matter preservation in the sediments, as indicated by the variation in redox-sensitive elements, such as Mn, Cr or V, and by the δ13C record of benthic foraminifers. The Alboran Sea productivity variation during D/O cycles is explained by the succession of two climatic scenarios that led to latitudinal shifts of the westerly wind system. This mechanism would also account for the variability in the deep-water ventilation of the Western Mediterranean Sea.