Late Pliocene variations of the Mediterranean outflow

Khélifi, Nabil, Sarntheim, Michael, Frank, Martin, Andersen, Nils and Garbe-Schönberg, Dieter (2014) Late Pliocene variations of the Mediterranean outflow Marine Geology, 357 . pp. 182-194. DOI 10.1016/j.margeo.2014.07.006.

[img] Text
Khelifi_et_al_2014.pdf - Published Version
Restricted to Registered users only

Download (4Mb) | Contact

Supplementary data:

Abstract

Late Pliocene changes in the advection of Mediterranean Outflow Water (MOW) derivates were reconstructed at northeast Atlantic DSDP/ODP sites 548 and 982 and compared to records of WMDW at West Mediterranean Site 978. Neodymium isotope (εNd) values more positive than −10.5/−11 reflect diluted MOW derivates that spread almost continuously into the northeast Atlantic from 3.7 to 2.55 Ma, reaching Rockall Plateau Site 982 from 3.63 to 2.75 Ma. From 3.4 to 3.3 Ma average MOW temperature and salinity increased by 2°–4 °C and ~1 psu both at proximal Site 548 and distal Site 982. The rise implies a rise in flow strength, coeval with a long-term rise in both west Mediterranean Sea surface salinity by almost 2 psu and average bottom water salinity (BWS) by ~1 psu, despite inherent uncertainties in BWS estimates. The changes were linked with major Mediterranean aridification and a drop in African monsoon humidity. In contrast to model expectations, the rise in MOW salt discharge after 3.4 Ma did not translate into improved ventilation of North Atlantic Deep Water, since it possibly was too small to significantly influence Atlantic Meridional Overturning Circulation. Right after ~2.95 Ma, with the onset of major Northern Hemisphere Glaciation, long-term average bottom water temperature (BWT) and BWS at Site 548 dropped abruptly by ~5 °C and ~1–2 psu, in contrast to more distal Site 982, where BWT and BWS continued to oscillate at estimates of ~2 °C and 1.5–2.5 psu higher than today until ~2.6 Ma. We relate the small-scale changes both to a reduced MOW flow and to enhanced dilution by warmwaters of a strengthenedNorth Atlantic Current temporarily replacingMOWderivates at Rockall Plateau.

Document Type: Article
Additional Information: WOS:000346542700014
Keywords: Pliocene, Onset of major Northern Hemisphere, Glaciation, Mediterranean Sea Mediterranean OutflowWater North African aridification, Atlantic Meridional Overturning Circulation, Intermediate waters
Research affiliation: Kiel University > Faculty of Mathematics and Natural Sciences > Institute of Geosciences
OceanRep > The Future Ocean - Cluster of Excellence > FO-R09
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Kiel University > Other > Leibniz-Laboratory for Radiometric Dating and Isotope Research
Refereed: Yes
DOI etc.: 10.1016/j.margeo.2014.07.006
ISSN: 0025-3227
Projects: IODP, Laptev Sea System, Transdrift
Date Deposited: 05 Jan 2015 09:09
Last Modified: 27 Feb 2017 15:24
URI: http://eprints.uni-kiel.de/id/eprint/26646

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...