A major and long-term Pliocene intensification of the Mediterranean Outflow, 3.5-3.3 Ma ago

Largely continuous millennial-scale records of benthic delta O-18, Mg/Ca-based temperature, and salinity variations in bottom waters were obtained from Deep Sea Drilling Project (DSDP) Site 548 (East Atlantic continental margin near Ireland, 1250 m water depth) for the period 3.7-3.0 Ma ago. High ep...

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Bibliographic Details
Published in:Geology
Main Authors: Khelifi, Nabil, Sarntheim, Michael, Andersen, Nils, Blanz, Thomas, Frank, Martin, Garbe-Schönberg, C.-Dieter, Haley, Brian, Stumpf, Roland, Weinelt, Mara
Format: Article in Journal/Newspaper
Language:English
Published: GSA, Geological Society of America 2009
Subjects:
North Atlantic Deep Water
North Atlantic
Online Access:https://oceanrep.geomar.de/id/eprint/3056/
https://oceanrep.geomar.de/id/eprint/3056/1/714_Kh%C3%A9lifi_2009_AMajorAndLongtermPliocene_Artzeit_pubid12176.pdf
https://doi.org/10.1130/G30058A.1
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Summary:Largely continuous millennial-scale records of benthic delta O-18, Mg/Ca-based temperature, and salinity variations in bottom waters were obtained from Deep Sea Drilling Project (DSDP) Site 548 (East Atlantic continental margin near Ireland, 1250 m water depth) for the period 3.7-3.0 Ma ago. High epsilon(Nd) values of -10.7 to -9 show that this site monitored changes in Mediterranean Outflow Water (MOW) throughout the mid-Pliocene. Bottom water variability at Ocean Drilling Progam (ODP) Site 978 (Alboran Sea, 1930 m water depth) provides a complementary record of MOW composition near its West Mediterranean source. Both sites show a singular and persistent rise in bottom water salinities by 0.7-1.4 psu, and in densities by similar to 1 kg m(-3) from 3.5 to 3.3 Ma ago, which is matched by an similar to 3 degrees C increase in bottom water temperature at Site 548. This event suggests the onset of strongly enhanced deep-water convection in the Mediterranean Sea and a related increase in MOW flow as a result of major aridification in the Mediterranean source region. In harmony with model suggestions, the enhanced MOW flow has possibly intensified Upper North Atlantic Deep Water formation.

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