Evidence for enhanced Mediterranean thermohaline circulation during rapid climatic coolings

Molecular biomarkers (C(37) alkenones, n-nonacosane and n-hexacosanol) and TOC are used together with benthic delta (18)O and delta (13)C data to document the hydrographic response of the western Mediterranean Sea to rapid climatic variability. These proxies are recorded in core MD 95-2043 (Alboran Sea) affording the study of the Dansgaard-Oeschger (D-O) and Heinrich (HE) variability during the last glacial period. The results suggest that rapid changes in the western Mediterranean thermohaline circulation occurred in parallel to sea surface temperature oscillations. Enhanced deep water ventilation occurred during cold intervals (HE and D-O Stadials) probably driven by a strengthening of north-westerly wind over the north-western Mediterranean Sea. In contrast, decreased intensity of the thermohaline circulation is detected during warm intervals (D-O Interstadials) which led to low oxygenated deep water masses and better preservation of the organic matter in the sediment. (C) 2000 Elsevier Science B.V. All rights reserved.