Evidence for enhanced Mediterranean thermohaline circulation during rapid climatic coolings

Molecular biomarkers (C-37 alkenones, n-nonacosane and n-hexacosanol) and T OC are used together with benthic delta O-18 and delta C-13 data to documen t the hydrographic response of the western Mediterranean Sea to rapid clima tic variability. These proxies are recorded in core MD 95-2043 (Alboran Sea ) affording the study of the Dansgaard-Oeschger (D-O) and Heinrich (HE) var iability during the last glacial period. The results suggest that rapid cha nges in the western Mediterranean thermohaline circulation occurred in para llel to sea surface temperature oscillations. Enhanced deep water ventilati on 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 d etected during warm intervals (D-O Interstadials) which led to low oxygenat ed deep water masses and better preservation of the organic matter in the s ediment. (C) 2000 Elsevier Science B.V. All rights reserved.