Stable isotope ratios and paleoceanaographic reconstructions from sediment cores 80-548 and 161-978A

• Main Authors: Khélifi, Nabil, Sarnthein, Michael, Andersen, Nils, Blanz, Thomas, Frank, Martin, Garbe-Schönberg, Dieter, Haley, Brian A, Stumpf, Rick, Weinelt, Mara
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2009
• Subjects: 161-978A; 80-548; Alboran Sea; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; Glomar Challenger; Joides Resolution; Leg161; Leg80; North Atlantic/SPUR; Ocean Drilling Program; ODP; North Atlantic Deep Water; North Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.716848; https://doi.org/10.1594/PANGAEA.716848

Largely continuous millennial-scale records of benthic d18O, Mg/Ca-based temperature, and salinity variations in bottom waters were obtained from Deep Sea Drilling Project Site 548 (eastern Atlantic continental margin south of Ireland, 1250 m water depth) for the period between 3.7 and 3.0 million years ago. This site monitored mid-Pliocene changes in Mediterranean Outflow Water (MOW) documented by continuously high Nd values between -10.7 and -9. Site 978 (Alboran Sea, 1930 m water depth) provides a complementary record of bottom water variability in the westernmost Mediterranean Sea, which is taken to represent MOW composition at its source. Both sites are marked by a singular and persistent rise in bottom water salinities by 0.7-1.4 psu and in densities by ~1 kg m-3 from 3.5 to 3.3 Ma, which is matched by an average 3 °C increase in bottom water temperatures at Site 548. This event suggests the onset of strongly enhanced deep-water convection in the Mediterranean Sea and a related strengthened MOW flow, which implies a major aridification of the Mediterranean source region. In harmony with model suggestions, the enhanced MOW flow has possibly intensified Upper North Atlantic Deep Water formation.